Kuala Lumpur, Malaysia
Kuala Lumpur, Malaysia

The University of Malaya is a public research university located in Kuala Lumpur, Malaysia. It is the oldest and most esteemed university in Malaysia. The university's name was abbreviated as Malaya during the pre-independence period.The university was founded in 1949 as a public-funded tertiary institution. Today, it has more than 2,500 faculty members. In 2012, UM was granted autonomy status by the Ministry of Higher Education.In 2014, the QS World University Rankings has ranked UM at the 151st place of the world. Wikipedia.

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Moradiya Y.,SUNY Downstate Medical Center | Janjua N.,University of Malaya
Journal of Stroke and Cerebrovascular Diseases | Year: 2013

Background: Recent studies comparing the outcomes of wake-up stroke (WUS) and stroke while awake (SWA) patients reveal better outcomes among SWA patients, attributable in part to their higher rates of thrombolysis. Patients with WUS are largely excluded from therapy. Earlier analyses, conducted before the approval of alteplase for acute stroke, show the true divergence of natural histories between these 2 groups. Methods: We analyzed 17,398 patients with ischemic stroke from the International Stroke Trial and compared both presentations and outcomes between the WUS and SWA groups. Severity was assessed by level of consciousness, Oxfordshire Community Stroke Project (OCSP) stroke classification, number of neurologic deficits, and predicted probability of dependency or death. Outcomes were assessed at day 14 and at 6 months. Outcome assessments were controlled for potential confounders. Results: WUS represented 29.6% of all ischemic strokes. More severe OSCP stroke type (total anterior circulation syndrome) was less common in WUS. Although more patients with WUS were alert at presentation with a lower predicted probability of dependency, the 14-day mortality rates and rates of poor outcome at 6 months were similar between the 2 groups. Conclusions: WUS patients comprise one quarter to one third of ischemic stroke patients. Despite their more benign presentations, they deteriorate to outcome rates similar to SWA. Although they are typically excluded from time-dependent acute interventions, patients with WUS may benefit from acute intervention to prevent this worsening natural history. © 2013 Elsevier B.V. All rights reserved.

Zukerman-Schpector J.,Federal University of São Carlos | Otero-De-La-Roza A.,University of Oviedo | Luana V.,University of Oviedo | Tiekink E.R.T.,University of Malaya
Chemical Communications | Year: 2011

As(lone pair)⋯π interactions provide stability to their crystal structures often leading to supramolecular chains and prevailing over As⋯X secondary contacts. The interaction (ca 8 kJ mol-1) arises from polarisation induced in the aryl ring by the As-lone pair plus the weak sharing of these electrons with the ring-C atoms. © 2011 The Royal Society of Chemistry.

Tiekink E.R.T.,University of Malaya | Zukerman-Schpector J.,Federal University of São Carlos
Chemical Communications | Year: 2011

Crystal structures of transition and main group element 1,1-dithiolates are shown to be partially sustained by C-H⋯π(chelate) interactions. For the planar binary bisdithiocarbamates, C-H⋯π(MS2C) interactions lead to aggregation patterns ranging from a 0-D four molecule aggregate to a 3-D architecture but with the majority of structures featuring 1-D or 2-D supramolecular assemblies. © 2011 The Royal Society of Chemistry.

Freeman M.A.,University of Malaya | Shinn A.P.,University of Stirling
Parasites and Vectors | Year: 2011

Background: Myxosporeans are known from aquatic annelids but parasitism of platyhelminths by myxosporeans has not been widely reported. Hyperparasitism of gill monogeneans by Myxidium giardi has been reported from the European eel and Myxidium-like hyperparasites have also been observed during studies of gill monogeneans from Malaysia and Japan. The present study aimed to collect new hyperparasite material from Malaysia for morphological and molecular descriptions. In addition, PCR screening of host fish was undertaken to determine whether they are also hosts for the myxosporean. Results: Heavy myxosporean infections were observed in monogeneans from two out of 14 fish and were detected from a further five fish using specific PCRs and pooled monogenean DNA. Positive DNA isolates were sequenced and were from a single species of myxosporean. Myxospore morphology was consistent with Myxidium with histozoic development in the parenchymal tissues of the monogenean. Simultaneous infections in the fish could not be confirmed microscopically; however, identical myxosporean DNA could be amplified from kidney, spleen and intestinal tract tissues using the specific PCR. Small subunit (SSU) rDNA for the myxosporean was amplified and was found to be most similar (92%) to that of another hyperparasitic myxosporean from a gill monogenean from Japan and to numerous multivalvulidan myxosporeans from the genus Kudoa (89-91%). Phylogenetic analyses placed the hyperparasite sequence basally to clades containing Kudoa, Unicapsula and Sphaerospora. Conclusions: The myxosporean infecting the gill monogenean, Diplectanocotyla gracilis, from the Indo-Pacific tarpon, Megalops cyprinoides, is described as a new species, Myxidium incomptavermi, based on a histozoic development in the monogenean host and its phylogenetic placement. We have demonstrated for the first time that a myxosporean hyperparasite of gill monogeneans is detectable in the fish host. However, myxospores could not be isolated from the fish and confirmation was by PCR alone. The relationship between the myxosporean infection in gill monogeneans and the presence of parasitic DNA in fish is not yet fully understood. Nonetheless, myxospores with a Myxidium-like morphology, two of which we have shown to be phylogenetically related, have now been reported to develop in three different gill monogeneans, indicating that myxosporeans are true parasites of monogeneans. © 2011 Freeman and Shinn; licensee BioMed Central Ltd.

Hutchison C.S.,University of Malaya
Journal of Asian Earth Sciences | Year: 2010

Seismic records, combined with dredged samples and a core, indicate that the Spratly Islands of the Dangerous Ground Province are constructed of presently active carbonate build-ups, known to extend back continuously at least to the Pleistocene and presumed to have initiated in the Miocene, most likely upon the crests of sea-floor cuestas that trend north-east-south-west parallel to the sea-floor spreading magnetic anomalies of the contiguous abyssal plain of the southern part of the South China Sea. The cuestas range from spectacular to subdued, constructed of Triassic and Cretaceous strata and no older rocks have been identified from dredges.The cuesta axes plunge towards the south-west away from the islands, suggesting that the reefs began colonising their more elevated parts, but the timing is uncertain. The highest seismically recorded cuesta crest is in 440. m of water and the islands and reefs are generally closely surrounded by water deeper than 1500. m. Since the so-called Mid-Miocene Unconformity (MMU), the region has been undergoing post-rift thermal subsidence. However, the nearby seismic lines show no evidence of drowned carbonate reefs. It is suggested that the coral-algal reefs colonised the crests of the most elevated cuestas that have maintained stability as shown by the 165. m core of one reef indicating periodic exposure with caliche horizons. Deepening water has protected the build-ups from extinction by post-rift draping strata in contrast to the Central Luconia Province, and the build-ups have been able to keep up with regional thermal subsidence.The dredged Mesozoic strata indicate that the Dangerous Ground is not exotic and should be interpreted as an integral part of the pre-rift Sundaland continent that included South China, Vietnam, Peninsular Malaysia, western Sarawak and possibly part of Sabah. Igneous and metamorphic samples have been dredged. Although individual spot K/Ar dates cannot be accepted at face value, such rocks can also be interpreted as an integral part of Sundaland. Post-MMU dredged samples are predominantly deep-water calcareous mudstones typified by the draping strata of the Ocean Drilling Program (ODP) Site 1143 cored from Recent to Late Miocene. © 2010 Elsevier Ltd.

Ooi C.H.R.,University of Malaya | Gong Q.,Peking University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

We study the quantum correlation of photon pairs from a double Raman particle driven by laser fields in a modified photon density of states such as a cavity or a defect in a photonic crystal. We obtain an exact semianalytical expression for the photon correlation, which is characterized by two complex decay functions associated with the levels splitting (effective Rabi frequencies) that depend on the control laser field. The position and width of the cavity density of state with respect to the anti-Stokes transition determine the features in the two-photon correlation profile. © 2012 American Physical Society.

Yuki N.,National University of Singapore | Shahrizaila N.,University of Malaya
Journal of Biomedicine and Biotechnology | Year: 2011

Molecular mimicry between self and microbial components has been proposed as the pathogenic mechanism of autoimmune diseases, and this hypothesis is proven in Guillain-Barré syndrome. Guillain-Barré syndrome, the most frequent cause of acute neuromuscular paralysis, sometimes occurs after Campylobacter jejuni enteritis. Gangliosides are predominantly cell-surface glycolipids highly expressed in nervous tissue, whilst lipo-oligosaccharides are major components of the Gram-negative bacterium C. jejuni outer membrane. IgG autoantibodies to GM1 ganglioside were found in the sera from patients with Guillain-Barré syndrome. Molecular mimicry was demonstrated between GM1 and lipo-oligosaccharide of C. jejuni isolated from the patients. Disease models by sensitization of rabbits with GM1 and C. jejuni lipo-oligosaccharide were established. Guillain-Barré syndrome provided the first verification that an autoimmune disease is triggered by molecular mimicry. Its disease models are helpful to further understand the molecular pathogenesis as well as to develop new treatments in Guillain-Barré syndrome. Copyright © 2011 Nortina Shahrizaila and Nobuhiro Yuki.

Das R.,University of Malaya | Ali M.E.,University of Malaya | Hamid S.B.A.,University of Malaya | Ramakrishna S.,National University of Singapore | Chowdhury Z.Z.,University of Malaya
Desalination | Year: 2014

Water pollutants have huge impacts on the entire living systems including terrestrial, aquatic, and aerial flora and fauna. In addition to conventional priority, and newly emerging micro/nano-pollutants, increasing global warming and consequent climate changes are posing major threats to the fresh water availability. Global warming and climate change are constantly increasing the salinity level of both land and sea water, dwindling the availability of existing fresh water for household, agriculture and industry. This has made it urgent to invent an appropriate water treatment technology that not only removes macro-, micro- and nano-pollutants but also desalinates water to a significant extent. Tip-functionalized nonpolar interior home of carbon nanotubes (CNTs) provides strong invitation to polar water molecules and rejects salts and pollutants. Low energy consumption, antifouling and self-cleaning functions have made CNT membranes extraordinary over the conventional ones. We comprehensively reviewed here molecular modeling and experimental aspects of CNT-membrane fabrication and functionalization for the desalination of both sea and brackish water. We present here the current problems and future challenges in water treatments. The article is potentially important for the hydrologists, membrane technologists, environmentalists and industrialists working in the field of water purification technologies to eradicate fresh water crisis in near future. © 2013 Elsevier B.V.

Shahrizaila N.,University of Malaya | Yuki N.,National University of Singapore
Expert Review of Neurotherapeutics | Year: 2011

Guillain-Barré syndrome (GBS) is typically classified into two major subtypes: acute inflammatory demyelinating neuropathy and acute motor axonal neuropathy. Its most recognizable variant is Fisher syndrome. The last two decades have seen considerable advances in our understanding of GBS. Of note, various autoantibodies against ganglioside antigens have been identified and found to have significant associations with the axonal forms of GBS and Fisher syndrome. In this article, we discuss the different clinical presentations in GBS and the role of antiganglioside antibodies in their underlying pathogenesis. We also discuss the impact that antiganglioside antibodies have had in the development of experimental models and treatment modalities in GBS. © 2011 Expert Reviews Ltd.

Abolfazli S.,University of Malaya | Sanaei Z.,University of Malaya | Ahmed E.,University of Malaya | Gani A.,University of Malaya | And 3 more authors.
IEEE Communications Surveys and Tutorials | Year: 2014

Recently, Cloud-based Mobile Augmentation (CMA) approaches have gained remarkable ground from academia and industry. CMA is the state-of-the-art mobile augmentation model that employs resource-rich clouds to increase, enhance, and optimize computing capabilities of mobile devices aiming at execution of resource-intensive mobile applications. Augmented mobile devices envision to perform extensive computations and to store big data beyond their intrinsic capabilities with least footprint and vulnerability. Researchers utilize varied cloud-based computing resources (e.g., distant clouds and nearby mobile nodes) to meet various computing requirements of mobile users. However, employing cloud-based computing resources is not a straightforward panacea. Comprehending critical factors (e.g., current state of mobile client and remote resources) that impact on augmentation process and optimum selection of cloud-based resource types are some challenges that hinder CMA adaptability. This paper comprehensively surveys the mobile augmentation domain and presents taxonomy of CMA approaches. The objectives of this study is to highlight the effects of remote resources on the quality and reliability of augmentation processes and discuss the challenges and opportunities of employing varied cloud-based resources in augmenting mobile devices. We present augmentation definition, motivation, and taxonomy of augmentation types, including traditional and cloud-based. We critically analyze the state-of-the-art CMA approaches and classify them into four groups of distant fixed, proximate fixed, proximate mobile, and hybrid to present a taxonomy. Vital decision making and performance limitation factors that influence on the adoption of CMA approaches are introduced and an exemplary decision making flowchart for future CMA approaches are presented. Impacts of CMA approaches on mobile computing is discussed and open challenges are presented as the future research directions. © 2014 IEEE.

Osterman E.,University of Ljubljana | Tyagi V.V.,University of Malaya | Butala V.,University of Ljubljana | Rahim N.A.,University of Malaya | Stritih U.,University of Ljubljana
Energy and Buildings | Year: 2012

One of the technologies which help to reduce energy consumption is the thermal energy storage for cooling applications where the cold is stored in phase change materials (PCMs). Such materials would be suitable for use in buildings because they can store a large amount of cold and phase change occurs at a constant temperature, thereby increasing thermal comfort. The aim of the study was to investigate how and where PCMs are used in the cooling systems, how are these systems related to buildings, if they provide lower energy consumption, how the indoor temperatures change due to PCMs and if the indoor air conditions improve. In this article are firstly presented materials that are suitable for such applications and desirable properties for use in such applications. A review of cooling systems follows, which are divided into four groups, namely: free cooling applications, encapsulated PCM systems, air-conditioning (AC) systems and sorption cooling systems, both with integrated PCMs. All studies have shown that the use of PCMs helps to improve energy performance of buildings, the problems were encountered in heat transfer and the amount of PCM needed for storage. These topics are also worthy of further research. © 2012 Elsevier B.V. All rights reserved.

Caracelli I.,Federal University of São Carlos | Zukerman-Schpector J.,Federal University of São Carlos | Tiekink E.R.T.,University of Malaya
Coordination Chemistry Reviews | Year: 2012

Consistent with macromolecular structures, Se(lone pair)...π(aryl) interactions are found in the crystal structures of molecular compounds. Supramolecular aggregation patterns based solely on these types of interactions were usually zero- or one-dimensional with a smaller number of examples of two- and three-dimensional architectures. The analysis proves that Se(lone pair)...π(aryl) interactions function as supramolecular synthons in the structural chemistry of selenium compounds. © 2011 Elsevier B.V.

Caracelli I.,Federal University of São Carlos | Haiduc I.,Babes - Bolyai University | Zukerman-Schpector J.,Federal University of São Carlos | Tiekink E.R.T.,University of Malaya
Coordination Chemistry Reviews | Year: 2013

A bibliographic review of the crystallographic literature reveals that Sb(lone pair), Bi(lone pair)...π(arene) interactions, where the lone pair of electrons is projected towards the centre of the arene ring, exist in the crystal structures of antimony(. III) and bismuth(. III) compounds and that, when operating in isolation of other supramolecular motifs, can stabilise clearly defined zero-, one- and two-supramolecular aggregates. Comparisons of closely related structures reveal systematic trends in the distance between the antimony(. III) and bismuth(. III) centre and the ring centroid of the interacting arene ring that are correlated with the Lewis acidity of the metal centre or the electronegativity of metal- or arene-bound substituents. © 2013 Elsevier B.V.

Krishnasamy G.,University of Malaya | Kulkarni A.J.,University of Windsor | Paramesran R.,University of Malaya
Expert Systems with Applications | Year: 2014

Clustering is an important and popular technique in data mining. It partitions a set of objects in such a manner that objects in the same clusters are more similar to each another than objects in the different cluster according to certain predefined criteria. K-means is simple yet an efficient method used in data clustering. However, K-means has a tendency to converge to local optima and depends on initial value of cluster centers. In the past, many heuristic algorithms have been introduced to overcome this local optima problem. Nevertheless, these algorithms too suffer several short-comings. In this paper, we present an efficient hybrid evolutionary data clustering algorithm referred to as K-MCI, whereby, we combine K-means with modified cohort intelligence. Our proposed algorithm is tested on several standard data sets from UCI Machine Learning Repository and its performance is compared with other well-known algorithms such as K-means, K-means++, cohort intelligence (CI), modified cohort intelligence (MCI), genetic algorithm (GA), simulated annealing (SA), tabu search (TS), ant colony optimization (ACO), honey bee mating optimization (HBMO) and particle swarm optimization (PSO). The simulation results are very promising in the terms of quality of solution and convergence speed of algorithm.© 2014 Elsevier Ltd. All rights reserved.

Sete E.A.,University of California at Riverside | Eleuch H.,McGill University | Ooi C.H.R.,University of Malaya
Journal of the Optical Society of America B: Optical Physics | Year: 2014

We analyze a scheme to entangle the movable mirrors of two spatially separated nanoresonators via a broadband squeezed light. We show that it is possible to transfer the Einstein-Podolsky-Rosen-type continuous-variable entanglement from the squeezed light to the mechanical motion of the movable mirrors. An optimal entanglement transfer is achieved when the nanoresonators are tuned at resonance with the vibrational frequencies of the movable mirrors and when strong optomechanical coupling is attained. Stationary entanglement of the states of the movable mirrors as strong as that of the input squeezed light can be obtained for sufficiently large optomechanical cooperativity, achievable in currently available optomechanical systems. The scheme can be used to implement long-distance quantum-state transfer provided that the squeezed light interacts with the nanoresonators. © 2014 Optical Society of America.

Morris D.J.,University of Stirling | Freeman M.A.,University of Malaya
International Journal for Parasitology | Year: 2010

All of the actinospore releasing oligochaetes collected in an environmental sample were found to be infected with the microsporidian Neoflabelliforma aurantiae n. gen. n. sp. Ultrastructural and phylogenetic studies on this microsporidian indicated similarities with Flabelliforma magnivora but not with the type species Flabelliforma montana, necessitating the formation of a new genus Neoflabelliforma and reassignment of F. magnivora as Neoflabelliforma magnivora n. comb. The development of N. aurantiae is described both parasitising the oligochaete worm and hyperparasitising the concurrent myxosporean infection. The effect of N. aurantiae on the myxosporeans was deleterious and progressive, eventually stopping all actinospore formation. Its discovery has the potential to impact on areas examining the phase of myxosporean life cycles in the invertebrate host, from transmission studies and epidemiology to re-evaluating the basic steps of intra-oligochaete development. Recent evidence has suggested that studies using invertebrate systems should consider possible adverse effects that co-infections can have on experimental outcomes. The discovery of N. aurantiae highlights the need for careful screening of experimental animals to help circumvent erroneous results. © 2009 Australian Society for Parasitology Inc.

Shahrizaila N.,University of Malaya | Yuki N.,National University of Singapore
Journal of Neurology, Neurosurgery and Psychiatry | Year: 2013

In the 1950s, Bickerstaff and Fisher independently described cases with a unique presentation of ophthalmoplegia and ataxia. The neurological features were typically preceded by an antecedent infection and the majority of patients made a spontaneous recovery. In the cases with Bickerstaff brainstem encephalitis, there was associated altered consciousness and in some, hyperreflexia, in support of a central pathology whereas in Fisher syndrome, patients were areflexic in keeping with a peripheral aetiology. However, both authors recognised certain similarities to Guillain-Barré syndrome such as the presence of peripheral neuropathy and cerebrospinal fluid albuminocytological dissociation. The discovery of immunoglobulin G anti-GQ1b antibodies in patients with Fisher syndrome and later in Bickerstaff brainstem encephalitis was crucial in providing the necessary evidence to conclude that both conditions were in fact part of the same spectrum of disease by virtue of their common clinical and immunological profiles. Following this, other neurological presentations that share anti-GQ1b antibodies emerged in the literature. These include acute ophthalmoparesis and acute ataxic neuropathy, which represent the less extensive spectrum of the disease whereas pharyngeal-cervical-brachial weakness and Fisher syndrome overlap with Guillain-Barré syndrome represent the more extensive end of the spectrum. The conditions can be referred to as the 'anti-GQ1b antibody syndrome'. In this review, we look back at the historical descriptions and describe how our understanding of Fisher syndrome and Bickerstaff brainstem encephalitis has evolved from their initial descriptions more than half a century ago.

Zukerman-Schpector J.,Federal University of São Carlos | Haiduc I.,Babes - Bolyai University | Tiekink E.R.T.,University of Malaya
Advances in Organometallic Chemistry | Year: 2012

An bibliographic review of the crystallographic literature describing transition metal carbonyl structures has been conducted in order to ascertain the prevalence of M-CO(lone pair)...π(arene) interactions. The geometric constraints were such to limit the search to a terminal carbonyl ligand interacting with a ring centroid of an arene ring, that is, for delocalized M-CO(lone pair)...π(arene) interactions operating in isolation of complementary supramolecular synthons. M-CO(lone pair)...π(arene) interactions were found to be important in stabilizing supramolecular architectures and to lead to, usually, zero-dimensional aggregation patterns. One-dimensional examples are also known and even a sole three-dimensional example is described. An evaluation of the crystal packing of a transition metal carbonyl structure is incomplete unless an analysis for M-CO(lone pair)...π(arene) is conducted. © 2012 Elsevier Inc.

A microsporidian hyperparasite, Desmozoon lepeophtherii, of the parasitic copepod Lepeophtheirus salmonis (salmon louse), infecting farmed Atlantic salmon (Salmo salar), was first discovered in the west of Scotland in 2000. Heavily infected salmon lice are easily recognised as they have large opaque inclusions distributed throughout the body. The prevalence of salmon lice with visible signs of microsporidiosis can be up to 10% of the population from certain farm sites. The microsporidian was also isolated from the host Atlantic salmon suggesting it may have a two host life cycle. The authors believe that the infection in immunocompetent salmon may be latent, becoming acute during periods of infection with another pathogen or during sexual maturation. Since its first discovery in Scotland, Desmozoon lepeophtherii has been subsequently reported from Norway, and more recently from the Pacific coast of North America. © 2011 Freeman and Sommerville; licensee BioMed Central Ltd.

Dahlui M.,University of Malaya
Singapore Medical Journal | Year: 2013

INTRODUCTION Cervical cancer is the third most common cancer among Malaysian women. However, the uptake of cervical cancer screening - Pap smear - by women in Malaysia has been low and remains a challenge. This study was conducted to assess the cervical screening practices of rural women in Malaysia and to examine the factors associated with such practices. METHODS A cross-sectional survey was conducted in five rural districts in Perak, Malaysia. 1,000 households were selected through multistage random sampling. Women aged 20-64 years were interviewed by trained enumerators using structured questionnaires. Binomial logistic regression was used to identify predictors of cervical screening through univariate and multivariate analyses. RESUlTS Among the 959 respondents, only 48.9% had undergone Pap smear at least once in the past three years. Women in the age group 40-49 years (odds ratio 3.027, 95% confdence interval 1.546-5.925; p < 0.005) were found to be signifcantly more likely to attend cervical cancer screening as compared to those in the age group 20-29 years. Other signifcant predictors were being married with children, having knowledge of cervical cancer symptoms, receiving relevant information regarding cervical cancer from health personnel or campaigns, being engaged in family planning and receiving encouragement from husbands. CONClUSION Efforts to boost the uptake of Pap smear screening among the rural population should be targeted toward the predictors of positive uptake.

Zukerman-Schpector J.,Federal University of São Carlos | Haiduc I.,Babes - Bolyai University | Tiekink E.R.T.,University of Malaya
Chemical Communications | Year: 2011

M-carbonyl(lone pair)⋯π(aryl) interactions provide stability to their transition metal crystal structures. This supramolecular synthon usually leads to zero- or one-dimensional aggregation patterns; a rare example of a three-dimensional architecture based on the M-CO(lone pair)⋯π(aryl) synthon has also been revealed. © The Royal Society of Chemistry 2011.

Tyagi V.V.,University of Malaya | Rahim N.A.A.,University of Malaya | Rahim N.A.,University of Malaya | Selvaraj J.A.L.,University of Malaya
Renewable and Sustainable Energy Reviews | Year: 2013

The development in solar PV technology is growing very fast in recent years due to technological improvement, cost reductions in materials and government support for renewable energy based electricity production. Photovoltaic is playing an important role to utilize solar energy for electricity production worldwide. At present, the PV market is growing rapidly with worldwide around 23.5 GW in 2010 and also growing at an annual rate of 35-40%, which makes photovoltaic as one of the fastest growing industries. The efficiency of solar cell is one of the important parameter in order to establish this technology in the market. Presently, extensive research work is going for efficiency improvement of solar cells for commercial use. The efficiency of monocrystalline silicon solar cell has showed very good improvement year by year. It starts with only 15% in 1950s and then increase to 17% in 1970s and continuously increase up to 28% nowadays. The growth in solar photovoltaic technologies including worldwide status, materials for solar cells, efficiency, factor affecting the performance of PV module, overview on cost analysis of PV and its environmental impact are reviewed in this paper. © 2012 Elsevier Ltd.

Ku C.Y.,National University of Singapore | Wong K.B.,University of Malaya
Journal of Combinatorial Theory. Series A | Year: 2013

Let B(n) denote the collection of all set partitions of [n]. Suppose A⊆B(n) is a non-trivial t-intersecting family of set partitions i.e. any two members of A have at least t blocks in common, but there is no fixed set of t blocks of size one which belong to all of them. It is proved that for sufficiently large n depending on t,|A|≤Bn-t-B~n-t-B~n-t-1+t where B n is the n-th Bell number and B~n is the number of set partitions of [n] without blocks of size one. Moreover, equality holds if and only if A is equivalent to{P∈B(n):{1},{2},...,{t},{i}∈Pfor somei∉{1,2,...,t,n}}∪{Q(i,n):1≤i≤t} where Q(i, n) = {{i, n}} ∪ {{j} : j ∈ [n] {set minus} {i, n}}. This is an analogue of the Hilton-Milner theorem for set partitions. © 2013 Elsevier Inc.

Zukerman-Schpector J.,Federal University of São Carlos | Tiekink E.R.T.,University of Malaya
CrystEngComm | Year: 2014

Dimethyl sulphoxide (DMSO) molecules in their all-organic solvates were shown to interact with arene rings of organic molecules via DMSO-O(lone pair)⋯π(arene) or DMSO-S(lone pair)⋯π(arene) interactions in approximately 5-6% of their crystal structures, often in conjunction with conventional hydrogen bonding involving the O(DMSO) atom, resulting in zero-, one- and two-dimensional supramolecular architectures. Zero-, one- and two-dimensional supramolecular architectures were also found to be sustained by parallel SO⋯π(arene) interactions operating in combination with hydrogen bonding. © 2014 the Partner Organisations.

Cheah Y.K.,University of Malaya | Naidu B.M.,Institute for Public Health
Asian Pacific Journal of Cancer Prevention | Year: 2012

Objective: The objective of present study is to investigate the determinants of smoking behaviour among adults in Malaysia. Method: Findings of the Third National Health and Morbidity Survey (NHMS-3) by the Ministry of Health, Malaysia, were used. The sample consisted of 34,539 observations. A logistic regression model was thus applied to estimate the probability to participate in smoking. Results: Age, income, gender, marital status, ethnicity, employment status, residential area, education, lifestyle and health status were statistically significant in affecting the likelihood of smoking. Specifically, youngsters, low income earners, males, unmarried individuals, Malays, employed individuals, rural residents and primary educated individuals were more likely to smoke. Conclusion: In conclusion, socio-demographic, lifestyle and health factors have significant impacts on smoking participation in Malaysia. Based on these empirical findings, several policy implications are suggested.

Pok E.-H.,University of Malaya | Lee W.-J.,National Taiwan University Hospital
World Journal of Gastroenterology | Year: 2014

Medical therapy for type 2 diabetes mellitus is ineffective in the long term due to the progressive nature of the disease, which requires increasing medication doses and polypharmacy. Conversely, bariatric surgery has emerged as a cost-effective strategy for obese diabetic individuals; it has low complication rates and results in durable weight loss, glycemic control and improvements in the quality of life, obesity-related co-morbidity and overall survival. The finding that glucose homeostasis can be achieved with a weight loss-independent mechanism immediately after bariatric surgery, especially gastric bypass, has led to the paradigm of metabolic surgery. However, the primary focus of metabolic surgery is the alteration of the physio-anatomy of the gastrointestinal tract to achieve glycemic control, metabolic control and cardio-metabolic risk reduction. To date, metabolic surgery is still not well defined, as it is used most frequently for less obese patients with poorly controlled diabetes. The mechanism of glycemic control is still incompletely understood. Published research findings on metabolic surgery are promising, but many aspects still need to be defined. This paper examines the proposed mechanism of diabetes remission, the efficacy of different types of metabolic procedures, the durability of glucose control, and the risks and complications associated with this procedure. We propose a tailored approach for the selection of the ideal metabolic procedure for different groups of patients, considering the indications and prognostic factors for diabetes remission. © 2014 Baishideng Publishing Group Inc. All rights reserved.

Agency: Cordis | Branch: FP7 | Program: CP-FP-SICA | Phase: HEALTH.2011.2.3.3-2 | Award Amount: 7.35M | Year: 2011

Current surveillance systems and control efforts are clearly insufficient to combat dengue in endemic countries and to prevent spread to previously uninfected areas (including Europe). We will focus on the following aspects of the call: better diagnosis, surveillance, prevention as well as prediction and/or prevention of the spread of Dengue fever to previously uninfected regions (including Europe) in the context of climate change. We will develop a rapid diagnostic assay for resource limited settings that can be used as point-of-care, is portable, provides rapid results and is inexpensive. Novel tools for vector monitoring will be tested. We propose to develop a comprehensive, early warning, laboratory-based sentinel surveillance system that integrates clinical, entomological, environmental, socio-economic, and weather/climate indices to evaluate predictive capability for epidemic dengue. The aim is to translate this information directly into improved tools for surveillance (early diagnostic assays, early warning systems and predictive models, risk maps, improved tools for vector surveillance). Furthermore, we will test the impact of a novel community-based strategy on the reduction of dengue incidence in school aged children. Lastly, the integrated information on trends of importation of dengue, global mobility patterns, and vector distribution under changing climate conditions will improve our current understanding of the risk of introduction into previously uninfected areas, in particular Europe. Web based predictive tools, models and maps will be produced. The information will be disseminated to relevant agencies, academia and policy makers and will translate into improved surveillance and control.

Koohi-Kamali S.,University of Malaya | Rahim N.A.,University of Malaya | Panwar N.L.,Maharana Pratap University of Agriculture and Technology | Mokhlis H.,University of Malaya
Renewable and Sustainable Energy Reviews | Year: 2013

The ever increasing penetration of renewable energy systems (RESs) in today deregulated intelligent power grids, necessitates the use of electrical storage systems. Energy storage systems (ESSs) are helpful to make balance between generation and demand improving the performance of whole power grid. In collaboration with RESs, energy storage devices can be integrated into the power networks to bring ancillary service for the power system and hence enable an increased penetration of distributed generation (DG) units. This paper presents different applications of electrical energy storage technologies in power systems emphasizing on the collaboration of such entities with RESs. The role of ESSs in intelligent micropower grids is also discussed where the stochastic nature of renewable energy sources may affect the power quality. Particular attention is paid to flywheel storage, electrochemical storage, pumped hydroelectric storage, and compressed air storage and their operating principle are discussed as well. The application of each type in the area of power system is investigated and compared to others. © 2013 Elsevier Ltd.

Omar M.,University of Malaya | Yeo I.,UTAR
International Journal of Production Economics | Year: 2014

In this paper, we proposed a model for an inventory system that satisfies a continuous time-varying demand for a finished product over a known and finite planning horizon by supplying both new and repaired items. New items are fabricated from a single type of raw material procured from external suppliers, while used items are collected from the customers and then repaired to a condition that is as-good-as-new. During each time interval, new items and used items are produced from multiple production and repair runs. The problem is to determine a joint policy for raw materials procurement, new items fabrication, and used items repair such that the total relevant cost of the model is minimized. We also proposed a numerical solution procedure and we tested the model with some numerical examples and a simple sensitivity analysis. © 2014 Elsevier B.V. All rights reserved.

News Article | December 21, 2016
Site: www.nature.com

The gastroenterology ward at the Prince of Wales Hospital in Hong Kong has undergone a dramatic change under the watchful eyes of gastroenterologist Siew Ng and her colleagues. When Ng started seeing patients there nearly seven years ago, she mainly encountered infectious diseases such as intestinal tuberculosis that ravage the gastrointestinal tract. But today, the ward is overwhelmed by young men and women with inflammatory bowel disease (IBD), a lifelong gastrointestinal condition that can be debilitating if left untreated (see 'Preparing for the burden'). “I can hardly keep up with all the patients I have,” says Ng. “The number of cases is basically exploding. And she has the data to support this statement. Ng also leads the Asia-Pacific Crohn's and Colitis Epidemiology Study (ACCESS), which, for the past five years, has tracked new cases of Crohn's disease and ulcerative colitis — the two major forms of IBD — across 13 countries in Asia as well as Australia. The incidence of IBD in Hong Kong has grown from just 1 case in a million in 1985 to a little over 30 in every million in 2014 (ref. 1). In countries such as the United States, the United Kingdom and Canada, the rate of IBD is much higher, with roughly 200–300 cases per million people. In fact, for a long time after IBD was first reported in the United Kingdom in the mid-1800s, it was thought of as a disease of European ancestry. But with the condition now appearing all around the world, the consensus is that anyone can get IBD. “IBD really is a global disease now,” says Ashwin Ananthakrishnan, an epidemiologist and clinician at the Massachusetts General Hospital Crohn's and Colitis Center in Boston. “If you look at the sheer number of patients, there are probably more in India and China than in North America.” The continuing surge in cases is providing research opportunities for clinicians such as Ng. Like other immune-related disorders such as multiple sclerosis and psoriasis, the incidence of IBD has risen in parallel with industrialization and urbanization, but the environmental drivers of IBD are not well understood. As people flock to cities, they have access to better health care and sanitation, but they are also exposed to poorer air quality, and are more likely to have sedentary, largely indoor lifestyles and to consume convenience diets that are high in saturated fat. Studies have linked factors such as these with IBD, but it is difficult to determine the origin in regions that have a long history of the disease. The ideal time to tease apart the complex web of environmental triggers and genetic associations, says Ng, is as urbanization is happening and before the incidence of IBD has peaked. The extent of environmental change may correlate with IBD's rise and characteristics, and could lead to new hypotheses about the causes. “The golden time for finding the cause of the disease is the next ten years,” says Ng. More than 200 genetic variants have been associated with IBD. In the first genetic-association study of IBD to include multiple ethnic groups — Europeans, East Asians, Indians and Iranians — 38 new loci (regions of the genome) with links to IBD were uncovered, 25 of which have previously been associated with other diseases or traits, such as multiple sclerosis or levels of cholesterol2. But the rise of IBD in Asia is not being driven by the emergence of new mutations — genetic changes occur over a much longer timescale than the global onset of IBD has taken. That does not mean, however, that genetics has nothing to offer in the quest to understand the increase of incidence in Asia. Genetic variants could provide clues to why environmental changes have greater impacts on some populations than on others, says Ananthakrishnan. Punjab state in northern India, for instance, has one of the highest incidences of ulcerative colitis in Asia — around 6 new cases in 100,000 people per year3. And the incidence of IBD in people of Indian descent who live in Malaysia is six times higher than that in indigenous Malaysians, and three times higher than that in those of Chinese descent4; clearly, some genetic risk factor is at play. Not all the genes or variants present the same risk across the globe. For example, the ATG16L1 gene — involved in the cellular recycling process autophagy — is associated with risk of Crohn's in white populations, but is not implicated in IBD in Asian people. And NOD2, a risk gene in individuals of European ancestry that is also connected with more aggressive forms of the disease, harbours different IBD-linked variants in Asian populations. What's more, the degree to which these genes explain the disease varies between different populations. In Asia, only 3% of people with IBD have a close relative with the disease, compared with 15% of individuals in the West5. As well as overall risk, certain gene variants may also correlate with particular presentations of IBD, Ananthakrishnan says. His work, which focuses on the environmental and genetic factors associated with IBD, suggests that an Indian person living in the West, for example, will have a type of Crohn's that is more similar to that seen in India than to cases in the West. Genetic and microbial data from different populations can also be used to help tailor treatments for people with IBD, says Jae Hee Cheon at Yonsei University College of Medicine in Seoul, who has conducted genetic, microbiome and epidemiological research in Koreans with IBD. For instance, the microbiota pills in development, which researchers hope to use to replace a pathogenic gut bacterial community with a healthy one, will not necessarily work for patients across the globe because patient populations vary in their disease features and response to treatment, he says. And finding the relevant genetic variants in smaller Asian countries is difficult, partly because the disease is still relatively rare. In Malaysia, for example, only about 2,000–3,000 people are thought to have IBD. That makes genome-wide association studies, which need many thousands of cases, nigh on impossible. The next best option for researchers is to pick handfuls of genetic variants identified as risk factors in larger studies, such as those done in the West, and test to see whether these variants pose a risk in smaller groups, says gastroenterologist Ida Hilmi at the University of Malaya in Kuala Lumpur. Risk factors One of the biggest questions Ananthakrishnan fields from people with IBD is how they can prevent their children from developing the disease. “It's a question that all of us working in the environmental-influence space want to answer,” he says. But at the moment, he can offer only a few general recommendations: avoid passive smoking, minimize antibiotic exposure in the early years and avoid giving children non-steroidal anti-inflammatory drugs, which can irritate the gut. For the most part, however, studies have shown these to be only risk factors, rather than proven interventions. Work to unpick the environmental factors behind IBD has a long way to go. Some of the clearest evidence for the role of the environment in IBD comes from studies of immigrants. For example, a large study of residents in Ontario, Canada, showed that South Asian immigrants have an incidence rate of roughly 70 new cases of IBD per million people per year6. Although that is still considerably lower than the annual rate for long-term residents of 240 per million, children of South Asian immigrants have an annual incidence rate that is nearly the same (60 per million) as the children of long-term residents (72 per million). One of the biggest surprises in this study was that the age at which immigrants arrive in Canada is a strong predictive factor for developing IBD, says paediatric gastroenterologist Eric Benchimol of the Children's Hospital of Eastern Ontario Research Institute in Ottawa, who led the study. For every decade older the person is when they arrive, the risk of IBD decreases by nearly 10%. This implies that there are factors in the new environment that, for certain genetic variations, increase the risk of IBD. Researchers suspect that the likeliest way the environment increases risk is by altering a person's gut bacteria. The main line of thought is that environmental triggers have a greater influence early in life, as the immune system and a full complement of gut bacteria develop and mature. “That's where the excitement is,” says Benchimol. Several large studies are under way in the United States and Canada to investigate the theory. In 2015, researchers at the University of Pennsylvania in Philadelphia showed that inflammation, antibiotic exposure and changes to diet independently alter the balance of gut microbes in children with Crohn's disease7. Treatment with a biological drug to decrease inflammation or dietary approaches seemed to normalize the composition of the microbiota. The ongoing Canadian Children Inflammatory Bowel Disease Network's CIDsCaNN study is collecting data from children with a new IBD diagnosis and following them for 18 months, including those with a South Asian background. Researchers are collecting stool samples to investigate the make-up of the microbiota, as well as recording information about early-life environmental risk factors, to try to understand what is triggering the disease. And a team at the University of Toronto in Canada is running a study called GEMINI (Generational Differences in Environmental Exposures caused by Migration: Impact on Incidence of Inflammatory Disease), to investigate risk factors in healthy first- and second-generation South Asian immigrants for IBD and other autoimmune diseases (such as type 1 diabetes and multiple sclerosis). Canada is the perfect place to conduct these studies, partly because its national-health registries make it easy to identify and track those with the disease, Benchimol says. Prospective studies such as CIDsCaNN, which follow individuals over time, are crucial for understanding the environmental factors that contribute to IBD. Ananthakrishnan is analysing data gathered through the Nurses' Health Study, a longitudinal study of more than 100,000 US women who have completed medical history and lifestyle questionnaires for decades. He found that women who ate high levels of fibre — about 24 grams per day — in the form of fruits and vegetables, were 40% less likely to get Crohn's disease than women who ate around half that8. Other studies have found similar trends for ulcerative colitis. High fibre intake has also been shown to prevent relapse in people with IBD, and animal models of IBD support the role of fibre in reducing the inflammatory damage wrought by the disease. Taken together, the move from a high-fibre diet towards a low-fibre Western diet, which seems to be happening in Asian cities in particular, might be part of the reason for the rise in IBD, Ananthakrishnan says. One limitation to applying findings from Western studies, such as the Nurses' Health Study, to what is happening in Asia is that participants are mainly of European ancestry. Although some factors, such as breastfeeding, seem to be universally protective, other environmental factors do not always carry the same weight across different ethnicities. Smoking, for instance, is one of the strongest risk factors for Crohn's disease in Western populations, but this was not the case for Asian participants in Ng's ACCESS cohort. ACCESS data also seem to suggest that antibiotic use — thought to be a risk factor in the West — is protective against IBD in Asian populations. But it can be more difficult to decipher relationships between antibiotic use and IBD in Asia, because the drugs can be bought over the counter in some countries, making it difficult to accurately record their use. To get to the heart of why the incidence of IBD in Asia is on the rise, rigorous studies based in the continent are needed. Ananthakrishnan thinks that the data sets gathered in the West are excellent models for understanding how environmental risk factors affect chronic disease. Researchers can use these both to narrow the scope of the exposure data and determine when and how often data are collected in Asian epidemiological studies of IBD, says gastroenterologist and epidemiologist Gilaad Kaplan of the University of Calgary in Canada. Ng and her collaborators are pursuing several lines of research as the incidence in Asia swells and their golden window of opportunity to identify the triggers begins to diminish. She is planning to compare the urban and rural populations of China, which are ethnically similar, but starkly different in their environmental exposures — from their dietary choices to whether they use flush toilets. Targeting areas in China that have a low incidence of IBD, such as Xiangshan County in Zhejiang and Chengdu, may help to uncover genetic and environmental factors that protect some individuals from the disease. Much research needs to be done, Ng says. “Every day, I go to work and I see new cases being referred, and I ask my colleague, 'Why has this disease dropped from the sky, out of nowhere? Where did it come from?” Researchers know that the best chance to find out is now.

News Article | October 28, 2015
Site: www.nature.com

The Islamic civilization lays claim to the world's oldest continually operational university. The University of Qarawiyyin was founded in Fes, Morocco, in ad 859, at the beginning of an Islamic Golden Age. Despite such auspicious beginnings, universities in the region are now in dire straits, as demonstrated by a report we have authored, released this week (see go.nature.com/korli3). The 57 countries of the Muslim world — those with a Muslim-majority population, and part of the Organisation of Islamic Cooperation (OIC) — are home to nearly 25% of the world's people. But as of 2012, they had contributed only 1.6% of the world's patents, 6% of its academic publications, and 2.4% of the global research expenditure1, 2 (see 'Quarter deck'). There have been only three Nobel laureates in the sciences from OIC countries; today these nations host fewer than a dozen universities in the top 400 of the many world rankings, and none in the top 100. To assess this situation, for the past two years we have led an international non-governmental and non-partisan task force of experts, formed by the Muslim World Science Initiative. The task force was chaired by Zakri Abdul Hamid, science adviser to the prime minister of Malaysia. It included a dozen experts and scholars — including policymakers, vice-chancellors, professors, and science communicators — from around the world. Our work confirmed many widely known problems, as highlighted by reports such as the Royal Society's 2014 Atlas of Islamic World Science and Innovation2. For example, OIC countries on average invest less than 0.5% of their gross domestic product (GDP) on research and development (R&D). Only Malaysia spends slightly more than 1% (the world average is 1.78%; most advanced countries spend 2–3%). Students in the Muslim world who participate in standardized international science tests lag well behind their peers worldwide, and the situation seems to be worsening3, 4. Our report highlights an even more problematic situation. University science programmes are using narrow content and outdated teaching methods. In most OIC countries, students are channelled into science or non-science streams around the age of 14, and their education thereafter is completely binary: science and technology students receive little in the way of humanities, social-science, language or arts education, and vice versa. Only one university in the region offers a programme in 'science and technology studies': the University of Malaya in Kuala Lumpur. To become beacons in society, OIC universities need to revitalize their teaching methods and meld science with liberal arts such as history and philosophy. For universities to become truly meritocratic, they must develop new ways of assessing faculty members to reward valuable research, teaching and outreach. And for this to happen, governments must give universities more autonomy. Our task force gathered data on science production for the 20 OIC countries that together have represented more than 90% of OIC scientific productivity over the past two decades. From the period 1996–2005 to 2006–15, most countries doubled or tripled their production of science papers. Qatar's output rocketed by a factor of 7.7, and Iran's by 7.6. But the number of scientific papers produced remains below the average of countries with similar GDP per capita. We found an average of 4.2 papers per dollar of GDP per capita for our OIC sample in the most recent decade, compared to an average of 8.6 for a group of 4 peer countries such as Brazil, Spain, South Korea, South Africa and Israel (see Supplementary Information). Papers from these OIC countries are cited less frequently than those from other nations. The average was 5.7 citations per paper for 2006–15, compared with 9.7 for South Africa and 13.8 for Israel, countries with a comparable GDP per capita. A list of the 100 most-cited papers since 1900 has none with a lead author from a Muslim-majority nation (see Nature 514, 550–553; 2014). Scientific research must be relevant and responsive to society's intellectual and practical needs. This dual goal seems to be out of sight — and often out of consideration — for most academic institutions in the region. For scientists and engineers to be creative, innovative and able to engage with questions of ethics, religion and the wider social purpose of research, students must receive a broad, liberal-arts-style education5. A few institutions attempt to relate their students' learning to their cultural backgrounds and contemporary knowledge. In the early 1970s, Tehran's Sharif University of Technology began a rich programme melding Islamic history, philosophy and culture with science and engineering. Its graduate programme in the philosophy of science remains the only one in the OIC that we are aware of. It is perhaps no coincidence that the most recent Times Higher Education world university rankings named Sharif University as the top Iranian university and number eight in the OIC. In recent years, US-style liberal-arts establishments have been set up in the region, modelled on the long-running and respected American University of Beirut and the American University in Cairo. One such is the American University of Sharjah (AUS) in the United Arab Emirates (UAE), which this year ranked seventh in the QS Rankings of universities in the 22 Arab countries. Fully home-grown and self-funded and with no formal affiliation with a US institution, the AUS requires science and engineering students to take roughly one-third of their required 40 or so courses in humanities, social sciences, language and communication. Habib University, founded last year in Karachi, Pakistan, also follows this model. Here, science and engineering students must take courses such as 'Understanding Modernity' and 'Hikma 1 & 2' — a two-course sequence that translates as 'traditional wisdom' — as well as many others that seek to create rounded rather than narrow engineering and science professionals. Other educational establishments should follow suit. Science classes themselves have serious problems. The textbooks used in OIC universities are often imported from the United States or Europe. Although the content is of a high standard, they assume a Western experience and use English or French as the language of instruction. This disadvantages many students, and creates a disconnect between their education and culture. To encourage the production of higher-quality, local textbooks and other academic material, universities need to reward staff for producing these at least as much as they do for research publication. Some basic facts are seen as controversial, and marginalized. Evolution, for example, is usually taught only to biology students, often as “a theory”, and is rarely connected to the rest of the body of knowledge. One ongoing study has found, for example, that most Malaysian physicians and medical students reject evolution (see go.nature.com/38cswo). Evolution needs to be taught widely and shown to be compatible with Islam and its culture6. Teaching the philosophy and history of science would help, too. The global consensus is that enquiry-based science education fosters the deepest understanding of scientific concepts and laws. But in most OIC universities, lecture-based teaching still prevails. Exceptions are rare. One is the Petroleum Institute, an engineering university in Abu Dhabi, UAE, where the faculty has created a hands-on experience with positive results on student interest and enrolment, particularly of women. Another problem is that faculty members rarely — if ever — receive any training or evaluation in pedagogy. This is true elsewhere in the world, but change is harder in many OIC nations. In most, curriculum changes, faculty appointments and promotions are set by ministry rules and decided by centralized commissions and bureaucracies. This leaves little room for universities to innovate. Universities in OIC nations need to be granted more autonomy to transform themselves into meritocracies that strive for scientific excellence and then lead rather than follow the winds of change towards greater transparency and meritocracy within their societies. Universities need to promote the right metrics, so that they do not inadvertently encourage plagiarism and junk science through pressure to publish. The region needs consistent data on science student and faculty profiles, curricula, pedagogy, language of instruction and so on, akin to what the Institute of Statistics of the United Nations Educational, Scientific and Cultural Organization collects — but at a fine-grained, university level. This is a task that must be undertaken by national or transnational bodies, such as the Islamic World Academy of Sciences (IAS) or the Islamic Educational, Scientific and Cultural Organization (ISESCO). We also call for reform of science curricula and pedagogy. Universities need to deliver more multidisciplinary, exploratory science education. A good start would be training for university teachers, with workshops on new tools and approaches. Barriers need to be broken between departments and colleges and new programmes constructed. Professors need to be free to teach topics that are not tightly regulated by ministries. There are grassroots efforts across the Muslim world to stimulate curiosity about science among students of all ages, operating without much government support. Ahmed Djebbar, an emeritus science historian at the University of Lille in France, has constructed an online, pre-university-level course called 'The Discoveries in Islamic Countries' available in three languages7, which relates science concepts to great discoveries and stories from the Islamic Golden Age. Such courses should be scaled up and shared by many institutions. Universities will need to implement reforms individually. We hope that the inspiration from a few islands of excellence will, in time, turn the tide of public and political opinion. There is precedent. In Pakistan, two private universities established in the 1980s — the Aga Khan University and Hospital in Karachi and Lahore University of Management Sciences — revolutionized medical and business education within a decade of their creation. Students elsewhere began demanding the standard set by these educational pioneers. The same can be done for science. Our task force is putting out an open call for universities across the Muslim world to join a voluntary Network of Excellence of Universities for Science (NEXUS), to be launched early next year. This peer group will be managed by the task force and housed in science adviser Zakri's office. We plan for NEXUS to run summer schools for university administrators, to monitor the progress of reforms at participating universities, and to issue a peer report card that will assess the performance of the universities in meeting milestones, thus recognizing and inspiring further improvements. True transformation will require much broader action from ministries, regulators and funding agencies, and these may be the most resistant to change. Without tough reforms, the dream of a scientific revival in the Muslim world will remain just that.

Agency: Cordis | Branch: FP7 | Program: CP-FP-SICA | Phase: HEALTH.2011.2.3.3-2 | Award Amount: 7.70M | Year: 2011

The overall concept of this research project is to assemble a consortium of international experts working together to develop new and innovative tools to be applied to the control of dengue in a global context. The core of the application focuses on parallel strategies aimed at: improving diagnosis and clinical management of dengue through two linked work packages designed a) to identify readily available clinical and laboratory parameters and/or viral and immunological markers, that differentiate between dengue and other common febrile illness within 3 days of fever onset, and b) to identify any of the available markers that are predictive of the likelihood of evolving to a more severe disease course assessing the risk of dengue spread though linked work packages focused on a) mapping and modelling techniques to define the current extent of dengue disease globally and to evaluate possible scenarios of spread or risk to previously uninfected regions in the future, and b) developing effective and affordable early warning and outbreak response systems. These four work packages are supported by a fifth work package dedicated to networking and translational activities to ensure that outputs from the various research activities are used to maximal advantage.

Chan C.-H.,University of Malaya | Yusoff R.,University of Malaya | Ngoh G.-C.,University of Malaya | Kung F.W.L.,Multimedia University
Journal of Chromatography A | Year: 2011

Microwave-assisted extraction (MAE) is widely employed in the analysis and the extraction of active compounds from plants. This review summarizes the research done during the last decade on the MAE of active ingredients from plants. Advances and modifications to improve the performance of MAE are presented and discussed in detail. Modified MAE such as vacuum microwave-assisted extraction (VMAE), nitrogen-protected microwave-assisted extraction (NPMAE), ultrasonic microwave-assisted extraction (UMAE), dynamic microwave-assisted extraction (DMAE) and other advancements in MAE are also detailed in this article. In addition, the microwave extraction procedures and the important parameters influencing its performance are also included, together with the advantages and the drawbacks of each MAE techniques. © 2011 Elsevier B.V.

Khadjeh Nassirtoussi A.,University of Malaya | Aghabozorgi S.,University of Malaya | Ying Wah T.,University of Malaya | Ngo D.C.L.,Sunway University
Expert Systems with Applications | Year: 2014

The quality of the interpretation of the sentiment in the online buzz in the social media and the online news can determine the predictability of financial markets and cause huge gains or losses. That is why a number of researchers have turned their full attention to the different aspects of this problem lately. However, there is no well-rounded theoretical and technical framework for approaching the problem to the best of our knowledge. We believe the existing lack of such clarity on the topic is due to its interdisciplinary nature that involves at its core both behavioral-economic topics as well as artificial intelligence. We dive deeper into the interdisciplinary nature and contribute to the formation of a clear frame of discussion. We review the related works that are about market prediction based on online-text-mining and produce a picture of the generic components that they all have. We, furthermore, compare each system with the rest and identify their main differentiating factors. Our comparative analysis of the systems expands onto the theoretical and technical foundations behind each. This work should help the research community to structure this emerging field and identify the exact aspects which require further research and are of special significance. © 2014 Elsevier Ltd. All rights reserved.

Quteishat A.,Al - Balqa Applied University | Lim C.P.,University of Science | Tan K.S.,University of Malaya
IEEE Transactions on Systems, Man, and Cybernetics Part A:Systems and Humans | Year: 2010

In this paper, a two-stage pattern classification and rule extraction system is proposed. The first stage consists of a modified fuzzy minmax (FMM) neural-network-based pattern classifier, while the second stage consists of a genetic-algorithm (GA)-based rule extractor. Fuzzy ifthen rules are extracted from the modified FMM classifier, and a don't care approach is adopted by the GA rule extractor to minimize the number of features in the extracted rules. Five benchmark problems and a real medical diagnosis task are used to empirically evaluate the effectiveness of the proposed FMM-GA system. The results are analyzed and compared with other published results. In addition, the bootstrap hypothesis analysis is conducted to quantify the results of the medical diagnosis task statistically. The outcomes reveal the efficacy of FMM-GA in extracting a set of compact and yet easily comprehensible rules while maintaining a high classification performance for tackling pattern classification tasks. © 2006 IEEE.

Ismail I.,University of Malaya | Ismail I.,Ministry of Health | Bulgiba A.,University of Malaya
PLoS ONE | Year: 2013

Background:Mortality among TB/HIV co-infected patients is still high particularly in developing countries. This study aimed to determine the predictors of death in TB/HIV co-infected patients during TB treatment.Methods:We reviewed medical records at the time of TB diagnosis and subsequent follow-up of all newly registered TB patients with HIV co-infection at TB clinics in the Institute of Respiratory Medicine and three public hospitals in the Klang Valley between January 2010 and September 2010. We reviewed these medical records again twelve months after their initial diagnosis to determine treatment outcomes and survival. We analysed using Kaplan-Meier and conducted multivariate Cox proportional hazards analysis to identify predictors of death during TB treatment in TB/HIV co-infected patients.Results:Of the 227 patients studied, 53 (23.3%) had died at the end of the study with 40% of deaths within two months of TB diagnosis. Survival at 2, 6 and 12 months after initiating TB treatment were 90.7%, 82.8% and 78.8% respectively. After adjusting for other factors, death in TB/HIV co-infected patients was associated with being Malay (aHR 4.48; 95%CI 1.73-11.64), CD4 T-lymphocytes count < 200 cells/μl (aHR 3.89; 95% CI 1.20-12.63), three or more opportunistic infections (aHR 3.61; 95% CI 1.04-12.55), not receiving antiretroviral therapy (aHR 3.21; 95% CI 1.76-5.85) and increase per 103 total white blood cell count per microliter (aHR 1.12; 95% CI 1.05-1.20)Conclusion:TB/HIV co-infected patients had a high case fatality rate during TB treatment. Initiation of antiretroviral therapy in these patients can improve survival by restoring immune function and preventing opportunistic infections. © 2013 Ismail and Bulgiba et al.

Shahabuddin N.S.,University of Malaya | Ahmad H.,University of Malaya | Yusoff Z.,Multimedia University | Harun S.W.,University of Malaya
IEEE Photonics Journal | Year: 2012

A new spacing-switchable multiwavelength erbium-doped fiber laser (EDFL) is demonstrated using switchable nonlinear polarization rotation (NPR) and stimulated Brillouin scattering (SBS) effects. The laser employs a 100-m-long photonic crystal fiber in conjunction with a four-port circulator in a figure-of-eight arrangement to provide the intensity-dependent transmission effect, as well as to discriminate the even-order and odd-order Brillouin Stokes to have a double-frequency Brillouin Stokes output. Without the Brillouin pump (BP), the laser operates in an NPR mode to produce at least 22 lasing wavelengths with a side mode suppression ratio of more than 10 dB and a wavelength spacing of 0.27 nm. In the Brillouin erbium fiber laser mode, at least 30 Brillouin lines with a spacing of 0.16 nm are obtained at BP power of 3 dBm and 980-nm pump power of 120 mW. © 2009 IEEE.

Wong Y.L.,University of Malaya | Ong C.S.,Multimedia University | Ngeow Y.F.,University of Malaya
Journal of Clinical Microbiology | Year: 2012

A variable-number tandem-repeat (VNTR) typing assay for the differentiation of Mycobacterium abscessus strains was developed. This assay showed complete reproducibility, locus stability, and a discriminatory power (Hunter-Gaston discriminatory index [HGDI] of 0.9563) that is superior to that of multilocus sequencing. It is a promising tool for the investigation of Mycobacterium abscessus epidemiology and nosocomial outbreaks. Copyright © 2012 American Society for Microbiology. All Rights Reserved.

Shahbaz M.,COMSATS Institute of Information Technology | Tang C.F.,University of Malaya | Shahbaz Shabbir M.,University of Illinois at Urbana - Champaign
Energy Policy | Year: 2011

The aim of this paper is to re-examine the relationship between electricity consumption, economic growth, and employment in Portugal using the cointegration and Granger causality frameworks. This study covers the sample period from 1971 to 2009. We examine the presence of a long-run equilibrium relationship using the bounds testing approach to cointegration within the Unrestricted Error-Correction Model (UECM). Moreover, we examine the direction of causality between electricity consumption, economic growth, and employment in Portugal using the Granger causality test within the Vector Error-Correction Model (VECM). As a summary of the empirical findings, we find that electricity consumption, economic growth, and employment in Portugal are cointegrated and there is bi-directional Granger causality between the three variables in the long-run. With the exception of the Granger causality between electricity consumption and economic growth, the rest of the variables are also bi-directional Granger causality in the short-run. Furthermore, we find that there is unidirectional Granger causality running from economic growth to electricity consumption, but no evidence of reversal causality. © 2011 Elsevier Ltd.

Meyer J.P.,Yale University | Cepeda J.,Yale University | Wu J.,University of Connecticut | Trestman R.L.,University of Connecticut | And 3 more authors.
JAMA Internal Medicine | Year: 2014

IMPORTANCE Human immunodeficiency virus (HIV) management in correctional settings is logistically feasible, but HIV-related outcomes before release have not been recently systematically examined. OBJECTIVE To evaluate HIV treatment outcomes throughout incarceration, including jail and prison. DESIGN, SETTING, AND PARTICIPANTS Retrospective cohort study of longitudinally linked demographic, pharmacy, and laboratory data on 882 prisoners within the Connecticut Department of Correction (2005-2012) with confirmed HIV infection, who were continually incarcerated 90 days or more, had at least 2 HIV-1 RNA and CD4 lymphocyte measurements, and were prescribed antiretroviral therapy. MAIN OUTCOMES AND MEASURES Three electronic databases (correctional, laboratory, and pharmacy) were integrated to assess HIV viral suppression (HIV-1 RNA levels, <400 copies/mL) on intake and release. Secondary outcomes were mean change in log-transformed HIV-1 RNA levels and mean change in CD4 lymphocyte count during incarceration. Demographic characteristics, prescribed pharmacotherapies, receipt of directly observed therapy, and duration of incarceration were analyzed as possible explanatory variables for HIV viral suppression in logistic regression models. RESULTS Among 882 HIV-infected prisoners with 1185 incarceration periods, mean HIV-1 RNA level decreased by 1.1 log10 and CD4 lymphocyte count increased by 98 cells/μL over time, with a higher proportion achieving viral suppression by release compared with entry (70.0% vs 29.8%; P < .001); 36.9%of antiretroviral therapy (ART) regimens were changed during incarceration. After adjusting for baseline HIV-1 RNA level, prerelease viral suppression correlated with female sex (adjusted odds ratio, 1.81; 95%CI, 1.26-2.59) and psychiatric disorder severity below the sample median (adjusted odds ratio, 1.50; 95%CI, 1.12-1.99), but not race/ethnicity, incarceration duration, ART regimen or dosing strategy, or directly observed therapy. CONCLUSIONS AND RELEVANCE Though just one-third of HIV-infected prisoners receiving ART entered correctional facilities with viral suppression, HIV treatment was optimized during incarceration, resulting in the majority achieving viral suppression by release. Treatment for HIV within prison is facilitated by a highly structured environment and, when combined with simple well-tolerated ART regimens, can result in viral suppression during incarceration. In the absence of important and effective community-based resources, incarceration can be an opportunity of last resort to initiate continuous ART for individual health and, following the "treatment as prevention" paradigm, potentially reduce the likelihood of HIV transmission to others after release if continuity of HIV care is sustained. © 2014 American Medical Association. All rights reserved.

Ismail I.,University of Malaya | Ismail I.,Ministry of Health | Bulgiba A.,University of Malaya
Preventive Medicine | Year: 2013

Objectives: To determine predictors of unsuccessful treatment in HIV-infected tuberculosis (TB) patients. Methods: We reviewed medical records at the time of TB diagnosis and subsequent follow-up of all registered TB patients with HIV co-infection at TB clinics in the Institute of Respiratory Medicine and three public hospitals in Malaysia between January 2010 and September 2010. We reviewed these medical records again twelve months after their initial diagnosis to determine treatment outcomes. Multiple logistic regression was conducted to identify risk factors for unsuccessful TB treatment. Results: Among the 219 patients analyzed, 53.4% achieved successful outcomes (cure, completed treatment) while 46.6% of patients had unsuccessful outcomes (default, treatment failure, died). After adjusting for other factors, unsuccessful outcome was associated with intravenous drug use (OR 2.72; 95% CI 1.44-5.16), not receiving antiretroviral therapy (OR 5.10; 95% CI 2.69-9.69), lymphadenopathy (OR 2.01; 95% CI 1.09-3.72) and low serum albumin (OR 4.61; 95% CI 1.73-12.27). Conclusion: Anti-retroviral treatment must be provided to all HIV-infected tuberculosis patients. Good immune and nutritional status needs to be assured in all HIV-infected tuberculosis patients. More studies are required in intravenous drug users to understand why tuberculosis treatment outcomes are poor in this group. © 2013 Elsevier Inc.

Ghasemi R.,Shiraz University of Medical Sciences | Haeri A.,Shahid Beheshti University of Medical Sciences | Dargahi L.,Shahid Beheshti University of Medical Sciences | Mohamed Z.,University of Malaya | Ahmadiani A.,University of Malaya
Molecular Neurobiology | Year: 2013

Historically, insulin is best known for its role in peripheral glucose homeostasis, and insulin signaling in the brain has received less attention. Insulin-independent brain glucose uptake has been the main reason for considering the brain as an insulin-insensitive organ. However, recent findings showing a high concentration of insulin in brain extracts, and expression of insulin receptors (IRs) in central nervous system tissues have gathered considerable attention over the sources, localization, and functions of insulin in the brain. This review summarizes the current status of knowledge of the peripheral and central sources of insulin in the brain, site-specific expression of IRs, and also neurophysiological functions of insulin including the regulation of food intake, weight control, reproduction, and cognition and memory formation. This review also considers the neuromodulatory and neurotrophic effects of insulin, resulting in proliferation, differentiation, and neurite outgrowth, introducing insulin as an attractive tool for neuroprotection against apoptosis, oxidative stress, beta amyloid toxicity, and brain ischemia. © 2012 Springer Science+Business Media, LLC.

Abbas H.F.,Sunway University | Baker I.F.,University of Malaya
International Journal of Hydrogen Energy | Year: 2011

The thermocatalytic decomposition of methane over activated carbon (AC) is proposed as a potential alternative for the production of hydrogen. The experiments were divided into two parts; the first part was conducted using thermogravimetric analyzer (TGA) while the second part was conducted in a bench-scale unit. For the first part, the research objective is to study the main and interaction effects of decomposition temperature (800-950 °C) and methane partial pressure (0.03-0.63 atm) on the initial specific rate of carbon formation by using statistical method. The experiments were carried out as a general full factorial design consisting of 20 experiments. Quadratic model was developed for initial specific rate of carbon formation in term of temperature and methane partial pressure using response surface methodology. The model's results show that not only the effects of the main parameters are important, but also the interaction effects between them are significant. For the second part, the main effects of decomposition temperature (775-850 °C) and AC weight (20-120 g) on the initial rate of methane decomposition by using the analysis of variance (ANOVA) were investigated. The results showed that AC weight has higher mean effects than decomposition temperature on the initial rate of methane decomposition. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Yusoff N.M.,Multimedia University | Salim S.S.,University of Malaya
Computers and Education | Year: 2012

E-learning storyboards have been a useful approach in distance learning development to support interaction between instructional designers and subject-matter experts. Current works show that researchers are focusing on different approaches for use in storyboards, and there is less emphasis on the effect of design and process difficulties faced by instructional designers and subject-matter experts. This study explores problem aspects of the cognitive task and the skills required of subject-matter experts by applying a cognitive task analysis approach from the expert point of view. The result shows that subject-matter experts face difficulties in making decisions on three elements during e-learning course development. The three elements are storyboard templates, prescriptive interactive components, and review process. It is found that the representation skills and decision making of the three elements allows subject-matter experts to decide on alternatives of the task process. The result also indicates that it is important to leverage the design and process skills of subject-matter experts as it affects their interaction with instructional designers. Three recommendations are made: training development, prescriptive interactive components development, and interaction design document development. A new framework can be recommended to train subject-matter experts as e-learning storyboard users, and in turn provide for effective interaction between them and instructional designers. © 2011 Elsevier Ltd. All rights reserved.

Ghauth K.I.,Multimedia University | Abdullah N.A.,University of Malaya
Educational Technology and Society | Year: 2011

One of the anticipated challenges of today's e-learning is to solve the problem of recommending from a large number of learning materials. In this study, we introduce a novel architecture for an e-learning recommender system. More specifically, this paper comprises the following phases i) to propose an e-learning recommender system based on content-based filtering and good learners' ratings, and ii) to compare the proposed e-learning recommender system with exiting e-learning recommender systems that use both collaborative filtering and content-based filtering techniques in terms of system accuracy and student's performance. The results obtained from the test data show that the proposed e-learning recommender system outperforms existing e-learning recommender systems that use collaborative filtering and content-based filtering techniques with respect to system accuracy of about 83.28% and 48.58%, respectively. The results further show that the learner's performance is increased by at least 12.16% when the students use the e-learning with the proposed recommender system as compared to other recommendation techniques. © International Forum of Educational Technology & Society (IFETS).

Haerian B.S.,University of Malaya | Haerian M.S.,Shahid Beheshti University of Medical Sciences
Pharmacogenomics | Year: 2013

The OPRM1 gene encodes the μ-opioid receptor, which is the primary site of action of most opioids. Several studies and three meta-analyses have examined a possible link between the exonic OPRM1 A118G (rs1799971) polymorphism and opioid dependence; however, results have been inconclusive. Therefore, a systematic review and meta-analysis have been carried out to examine whether this polymorphism is associated with opioid dependence. Thirteen studies (n = 9385), comprising 4601 opioid dependents and 4784 controls, which evaluated association of the OPRM1 rs1799971 polymorphism with susceptibility to opioids, were included in this study. Our meta-analysis showed significant association between this polymorphism and susceptibility to opioid dependence in overall studies under a codominant model, as well as susceptibility to opioid dependence or heroin dependence in Asians under an autosomal dominant model. The nonsynonymous OPRM1 rs1799971 might be a risk factor for addiction to opioids or heroin in an Asian population. © 2013 Future Medicine Ltd.

Reza A.W.,University of Malaya | Eswaran C.,Multimedia University
Journal of Medical Systems | Year: 2011

The increasing number of diabetic retinopathy (DR) cases world wide demands the development of an automated decision support system for quick and cost-effective screening of DR. We present an automatic screening system for detecting the early stage of DR, which is known as non-proliferative diabetic retinopathy (NPDR). The proposed system involves processing of fundus images for extraction of abnormal signs, such as hard exudates, cotton wool spots, and large plaque of hard exudates. A rule based classifier is used for classifying the DR into two classes, namely, normal and abnormal. The abnormal NPDR is further classified into three levels, namely, mild, moderate, and severe. To evaluate the performance of the proposed decision support framework, the algorithms have been tested on the images of STARE database. The results obtained from this study show that the proposed system can detect the bright lesions with an average accuracy of about 97%. The study further shows promising results in classifying the bright lesions correctly according to NPDR severity levels. © 2009 Springer Science+Business Media, LLC.

Agency: Cordis | Branch: FP7 | Program: CSA-CA | Phase: NMP-2008-2.6-3 | Award Amount: 2.04M | Year: 2009

A coordination action is proposed to reinforce the international dimension of EU research on nanomaterials in formulations in the Asia-Pasific region. Three mechanism will be implemented to reach the widest possible audience in the appropriate formats that are convenient to the different stakeholders: (1) yearly major events, that will introduce a new concept to scientific gatherings and a departure from conventional meetings, (2) a researchers exchange program to seed new collaborations, facilitate joint projects and the realisation of future coordinated calls, and (3) the creation of a website devoted to nanomaterials in formulations, that will include up to date and reliable information on the newest research developments, funding opportunities, regulations, events and links to other nanotechnology initiatives.

Agency: Cordis | Branch: FP7 | Program: CP-FP | Phase: ENV.2008. | Award Amount: 4.75M | Year: 2009

SHIVA aims to reduce uncertainties in present and future stratospheric halogen loading and ozone depletion resulting from climate feedbacks between emissions and transport of ozone depleting substances (ODS). Of particular relevance will be studies of short and very short-lived substances (VSLS) with climate-sensitive natural emissions. We will perform field studies of ODS production, emission and transport in understudied, but critical, regions of the tropics using ship, aircraft and ground-based instrumentation. We will parameterise potential climate sensitivities of emissions based on inter-dependencies derived from our own field studies, and surveys of ongoing work in this area. We will study the chemical transformation of ODS during transport from the surface to the tropical tropopause layer (TTL), and in the stratosphere, using a combination of aircraft and balloon observations together with process-oriented meso-scale modelling. These investigations will be corroborated by space-based remote sensing of marine phytoplankton biomass as a possible proxy for the ocean-atmosphere flux of ODS. From this a systematic emission inventory of VSLS ODS will be established to allow construction of future-climate scenarios. The impact of climate-sensitive feedbacks between transport and the delivery of ODS to the stratosphere, and their lifetime within it, will be studied using tracer observations and modelling. Further global modelling will assess the contribution of all ODS, including VSLS (which have hitherto normally been excluded from such models) to past, present and future ozone loss. Here, the sensitivity of natural ODS emissions to climate change parameters will be used in combination with standard IPCC climate model scenarios in order to drive measurement-calibrated chemical transport model (CTM) simulations for present and future stratospheric ozone; to better predict the rate, timing and climate-sensitivity of ozone-layer recovery.

Teh P.-L.,Multimedia University | Yong C.-C.,University of Malaya
Journal of Computer Information Systems | Year: 2011

This research investigates the roles of sense of self-worth, in-role behavior, and organizational citizenship behavior in supporting individuals' knowledge sharing behavior, by incorporating a motivational aspect into the theory of reasoned action. Structural equation modeling analysis of survey data from a group of 116 Information Systems personnel revealed that two variables (i.e., sense of self-worth and in-role behavior) are positively related to the attitude toward knowledge sharing. Both subjective norm and organizational citizenship behavior are independent and positively related to an intention to share knowledge, while the attitude toward knowledge sharing is negatively related to intention to share knowledge. Individuals' knowledge sharing behavior is predicted with more favorable intention to share knowledge. This research and its findings have implications for organizational administrators in Information Technology (IT) firms to enhance intrinsic motivation among employees, and develop better reciprocal relationships and interpersonal interactions of employees to facilitate successful knowledge sharing.

News Article | December 2, 2015
Site: www.nature.com

As former chairman of Pakistan's Higher Education Commission and former coordinator-general of the Organisation of Islamic Cooperation's science and technology body COMSTECH, I suggest that some universities in the Muslim world are not in such dire need of revitalization as Nidhal Guessoum and Athar Osama imply (Nature 526, 634–636; 2015). At least 3 such institutions are ranked in the world's top 250 — the University of Malaya in Kuala Lumpur, and King Fahd University and King Saud University, both in Saudi Arabia (see go.nature.com/4gfu2u). In 2013 and 2014, the Middle East Technical University, Istanbul Technical University and Bilkent University in Turkey were ranked in the top 400 globally (see go.nature.com/m6195d). Pakistan's National University of Sciences and Technology and the Pakistan Institute of Engineering and Applied Sciences were ranked in the top 200 Asian universities in 2014 (see go.nature.com/kdwt8w). The King Abdullah University of Science and Technology in Saudi Arabia and the Masdar Institute in Abu Dhabi are rising stars. According to 2014 data on scientific publications, Iran ranks 16th in the world, Turkey is 19th and Malaysia is 23rd — on a par with Switzerland, Taiwan and some Scandinavian countries, and ahead of South Africa (see go.nature.com/ms6fct). Furthermore, the requirements of the United Arab Emirates' Commission of Academic Accreditation (CAA) are more stringent than those of the US Accreditation Board for Engineering and Technology (ABET), for instance. Whereas the CAA requires faculty members to have the highest degree in their field (such as a PhD), ABET requires only appropriate qualifications. The CAA also requires universities to have accredited PhD programmes in addition to accredited bachelor's and master's degrees.

Hussan Md.J.,Monash University | Hassan M.Hj.,University of Malaya | Kalam Md.A.,University of Malaya | Memon L.A.,University of Malaya
Journal of Cleaner Production | Year: 2013

Alternative fuel research for the profusely growing number of diesel run automotive has intensified due to environmental reasons and turmoil in petroleum market. Government initiatives all around the world, their energy policies and steps to emphasis the use of biodiesel; proved biodiesel as a number one renewable substitute for No. 2 diesel fuels. Among all biodiesel feedstock, palm oil is a potential source with higher yield rate without much fertilizer use especially in tropical region. However, the application of transesterified palm biodiesel is objected by many auto-manufacturers due to adverse effects on engine in long term operation. The aim of this study was to modify the key fuel properties of palm biodiesel which causes engine fouling in long term operation. A significant amount of work is devoted to mix biodiesel and diesel at arbitrary percentages and test engine performance. Numerous fuel additives are developed for biodiesels automotive use. In this study, chemical properties of biodiesel are tailored by ethanol and an optimum formulation is derived mathematically. Ethanol is used at a controlled proportion (6%) with palm oil methyl ester (POME) as additive to reduce the higher viscosity of POME. This optimum palm biodiesel-ethanol blend was mixed at varying proportions (i.e. 0-30%) with No. 2 diesel to produce ternary blends of diesel-palm biodiesel-ethanol. Cold flow properties (such as, could point, pour point) of these ternary blends has improved and minute percentage of ethanol adding did not adversely affect the oxidation stability and corrosiveness of the fuel blend. Ethanol has significantly reduces the flash point, but the flammability of ternary blends is classified as Class II; similar to that of diesel. Cetane number is reduced in ternary blends by ethanol. So, palm biodiesel with minute percentage of anhydrous ethanol as additive in the ternary blend significantly improved key fuel properties significantly. © 2013 Elsevier Ltd. All rights reserved.

Pourtousi M.,University of Malaya | Sahu J.N.,University of Malaya | Sahu J.N.,Brunei Institute of Technology | Ganesan P.,University of Malaya
Chemical Engineering and Processing: Process Intensification | Year: 2014

The numerical approaches have been used in many studies to predict the flow pattern inside the bubble column reactors because of the difficulties that are still found in designing and scaling-up the bubble columns. This review makes an effort to show suitable interfacial forces i.e., drag force, lift force, turbulent dispersion models and virtual mass and turbulence models such as standard k-e model, Reynolds Stress Model, Large Eddy Simulation to predict flow pattern inside the bubble column using Eulerian-Eulerian. The effect of various interfacial forces and turbulence models on gas-liquid velocity and gas hold-up in bubble column is critically reviewed. © 2013 Elsevier B.V.

Mook W.T.,University of Malaya | Aroua M.K.,University of Malaya | Issabayeva G.,University Tunku Abdul Rahman
Renewable and Sustainable Energy Reviews | Year: 2014

Recent decades are characterized by incredible rapid technological development resulting in the introducing of various new chemicals, materials and processes with various complexities. This, in turn, is associated with release of increased amounts of pollutants into the environment and for this reason their efficient removal is required. Environmental monitoring results show that many pollutants in ground water are at the excess limit which raises concerns on currently employed wastewater treatments. This review summarizes the electrochemical technology used in wastewater treatment covering its advantages such as high removal efficiency, clean energy conversion, low environmental impact, easy operation and compact design. Significant enhancement of electrochemical methods such as electrocoagulation, electroflotation, electrooxidation, electroreduction and electrodisinfection is discussed and these technologies are combined with an advanced photovoltaic (PV) technology. Important design parameters to obtain the highest efficiency from this combined technology are discussed in details. Moreover, it is shown that the combination systems are capable to produce hydrogen gas at high efficiency which can be used as a supplementary source for green energy thus minimizing the entire process cost. © 2014 Elsevier Ltd.

Leong L.-Y.,University Tunku Abdul Rahman | Hew T.-S.,University of Malaya | Tan G.W.-H.,University Tunku Abdul Rahman | Ooi K.-B.,Linton University College
Expert Systems with Applications | Year: 2013

The main aim of this study is to determine the factors influencing the adoption of Near Field Communication (NFC)-enabled mobile credit card, an innovation in contactless payment for the future generation. Constructs from psychological science, trust-based and behavioral control theories were incorporated into the parsimonious TAM. Using empirical data and Structural Equation Modeling-Artificial Neural Networks approach together with multi group analysis, the effects of social influence, personal innovativeness in information technology, trust, perceived financial cost, perceived usefulness and perceived ease of use were examined. The significance of indirect effects was examined using the bias-corrected percentile with two-tailed significance through bootstrapping. Gender, age, experience and usage were introduced as the moderator variables with industry being the control variable in the research model. The scarcity in studies regarding the moderating effects of these variables warranted the needs to further investigate their impacts. The mediating effect of perceived usefulness was examined using the Baron-Kenny's technique. The findings of this study have provided invaluable theoretical, methodological and managerial implications and will contribute to the decision making process by CEOs, managers, manufacturers and policy makers from the mobile manufacturing industry, businesses and financial institutions, mobile commerce, mobile telecommunication providers, mobile marketers, private or government practitioners and etc.© 2013 Elsevier Ltd. All rights reserved.

Sakmani A.S.,University of Malaya | Lam W.-H.,University of Malaya | Hashim R.,University of Malaya | Chong H.-Y.,University Tunku Abdul Rahman
Renewable and Sustainable Energy Reviews | Year: 2013

Malaysia is a coastal country, with a long coastline in Peninsular Malaysia connecting the Strait of Malacca in the west and the South China Sea to the east. The Strait of Malacca is a well-known waterway allowing the continuous supply of oil by tankers from the Middle East to the Far East, such as China, Japan and Korea. The Strait of Malacca is also a strategic location for the harnessing of the tidal stream energy due to its strong tidal current resources. The abundant tidal resource in the Strait of Malacca is a focus of research. However, none of the local researchers have investigated the site selection in the Strait of Malacca to propose the installation of a tidal turbine in detail. This study investigates the tidal stream resources and the topology of the Strait of Malacca by using the data from acoustic Doppler current profiler (ADCP) in order to propose Pulau Pangkor (Pangkor Island) for the site of the exploitation of the tidal stream energy. © 2013 Elsevier Ltd.

Chong H.-Y.,University Tunku Abdul Rahman | Lam W.-H.,University of Malaya
Renewable and Sustainable Energy Reviews | Year: 2013

The need for renewable energy is a global demand due to both the economic factors and the environmental concerns. Malaysian government has been supportive on the research and development in the renewable energies. Renewable Energy Act (2011) and Sustainable Energy Development Authority Act (2011) have been enacted to boost the industry of renewable energy. This paper presents the current status and future prospects of renewable energy in Malaysia with particular focus on the ocean renewable energy. Five types of ocean renewable energy were reviewed including tidal barrage, tidal current energy, wave energy, Ocean Thermal Energy Conversion (OTEC) and salinity gradient power. The comparison of various types of ocean renewable energy has been made to present their recent technologies in electricity generation. Tidal current energy is identified as a preferable option particularly in the Straits of Malacca. © 2013 Elsevier Ltd.

Chung P.Y.,Monash University | Navaratnam P.,Monash University | Chung L.Y.,University of Malaya
Annals of Clinical Microbiology and Antimicrobials | Year: 2011

Background: There has been considerable effort to discover plant-derived antibacterials against methicillin-resistant strains of Staphylococcus aureus (MRSA) which have developed resistance to most existing antibiotics, including the last line of defence, vancomycin. Pentacyclic triterpenoid, a biologically diverse plant-derived natural product, has been reported to show anti-staphylococcal activities. The objective of this study is to evaluate the interaction between three pentacyclic triterpenoid and standard antibiotics (methicillin and vancomycin) against reference strains of Staphylococcus aureus.Methods and Results: The activity of the standard antibiotics and compounds on reference methicillin-sensitive and resistant strains of S. aureus were determined using the macrodilution broth method. The minimum inhibitory concentration (MIC) of the compounds was compared with that of the standard antibiotics. The interaction between any two antimicrobial agents was estimated by calculating the fractional inhibitory concentration (FIC index) of the combination. The various combinations of antibiotics and compounds reduced the MIC to a range of 0.05 to 50%.Conclusion: Pentacyclic triterpenoids have shown anti-staphylococcal activities and although individually weaker than common antibiotics produced from bacteria and fungi, synergistically these compounds may use different mechanism of action or pathways to exert their antimicrobial effects, as implicated in the lowered MICs. Therefore, the use of current antibiotics could be maintained in their combination with plant-derived antibacterial agents as a therapeutic option in the treatment of S. aureus infections. © 2011 Chung et al; licensee BioMed Central Ltd.

Ramesh S.,University of Malaya | Shanti R.,University Tunku Abdul Rahman | Morris E.,University Tunku Abdul Rahman
Carbohydrate Polymers | Year: 2012

A series of polymer electrolytes composed of corn starch (CS), lithium bis(trifluoromethanesulfonyl)imide (LITFSI) and deep eutectic solvent (DES) were fabricated by solution casting technique. The DES was synthesized from a mixture of choline chloride and urea at a molar ratio of 1:2. The addition of DES is crucial in enhancing the room temperature ionic conductivity by increasing the amorphous elastomeric phase in CS:LITFSI matrix. The ionic transport mechanism is improved and appreciable amount of ion conducting polymer electrolytes is produced. The highest ionic conductivity achieved for the polymer electrolyte composition CS:LiTFSI:DES (14 wt.%:6 wt.%:80 wt.%) is 1.04 × 10-3 S cm-1. The anomalies that were observed with the addition of DES upon formation of neutral ion multiples were visually revealed by the SEM micrographs. The possible dipole-dipole interaction between the constituents was visualized by the FTIR spectroscopy upon change in cage peaks. © 2011 Elsevier Ltd. All Rights Reserved.

Shahbaz M.,COMSATS Institute of Information Technology | Salah Uddin G.,Linköping University | Ur Rehman I.,University of Malaya | Imran K.,Institute of Business Management
Renewable and Sustainable Energy Reviews | Year: 2014

This paper investigates the relationship between industrialization, electricity consumption and CO2 emissions in case of Bangladesh using quarter frequency data over the period of 1975-2010. The ARDL bounds testing approach is applied to examine cointegration in the presence of structural breaks stemming in the series. The causal relationship among the variables is explored by applying the innovative accounting approach (IAA). Our results indicate that the variables are cointegrated for a long run relationship. We find that financial development adds in energy pollutants. Electricity consumption contributes to CO2 emissions. Trade openness also has a positive impact on energy pollutants. The results unveil that EKC is existed between industrial development and CO2 emissions in case of Bangladesh. Our causality analysis shows that electricity consumption Granger causes energy pollutants, industrial growth and financial development. The unidirectional causality exists running from financial development to trade openness and trade openness Granger causes industrial development. This study opens up new insights for policy makers in formulating a comprehensive economic, financial and trade policy to sustain industrialization by improving the environmental quality. © 2014 Elsevier Ltd.

Tang O.,Linköping University | Tang O.,Tongji University | Nurmaya Musa S.,Linköping University | Nurmaya Musa S.,University of Malaya
International Journal of Production Economics | Year: 2011

The purpose of this paper is to investigate the research development in supply chain risk management (SCRM), which has shown an increasing global attention in recent years. Literature survey and citation/co-citation analysis are used to fulfil the research task. Literature survey has undertaken a thorough search of articles on selected journals relevant to supply chain operations management. Meanwhile, citation/co-citation analysis uses Web of Sciences database to disclose SCRM development between 1995 and 2009. Both the approaches show similar trends of rising publications over the past 15 years. This review has piloted us to identify and classify the potential risk associated with different flows, namely material, cash and information flows. Consequently, we identify some research gaps. Even though there is a pressing need and awareness of SCRM from industrial aspect, quantitative models in the field are relatively lacking and information flow risk has received less attention. It is also interesting to observe the evolutions and advancements of SCRM discipline. One finding is that the intellectual structure of the field made statistically significant increase during 20002005 and evolved from passively reacting to vague general issues of disruptions towards more proactively managing supply chain risk from system perspectives. © 2010 Elsevier B.V. All rights reserved.

Beyrer C.,Center for Public Health and Human Rights | Malinowska-Sempruch K.,Open Society Institute | Kamarulzaman A.,University of Malaya | Kazatchkine M.,The Global Fund | And 2 more authors.
The Lancet | Year: 2010

The published work on HIV in people who use drugs shows that the global burden of HIV infection in this group can be reduced. Concerted action by governments, multilateral organisations, health systems, and individuals could lead to enormous benefits for families, communities, and societies. We review the evidence and identify synergies between biomedical science, public health, and human rights. Cost-effective interventions, including needle and syringe exchange programmes, opioid substitution therapy, and expanded access to HIV treatment and care, are supported on public health and human rights grounds; however, only around 10 of people who use drugs worldwide are being reached, and far too many are imprisoned for minor offences or detained without trial. To change this situation will take commitment, advocacy, and political courage to advance the action agenda. Failure to do so will exacerbate the spread of HIV infection, undermine treatment programmes, and continue to expand prison populations with patients in need of care. © 2010 Elsevier Ltd.

Liam C.-K.,University of Malaya | Wahid M.I.A.,Beacon International Specialist Center | Rajadurai P.,Monash University | Cheah Y.-K.,University Putra Malaysia | Ng T.S.-Y.,University Putra Malaysia
Journal of Thoracic Oncology | Year: 2013

Introduction: Despite available data from other Asian countries, the prevalence of epidermal growth factor receptor (EGFR) mutations among lung adenocarcinoma patients has not been reported in Malaysia. This study sought to determine the frequency of EGFR mutations among multiethnic Malaysian patients diagnosed with lung adenocarcinoma. Methods: Demographic and clinical information of patients whose lung adenocarcinoma biopsy specimens were submitted for EGFR mutation testing at Sime Darby Medical Center from 2009 to 2011 were analyzed. EGFR mutations at exons 18, 19, 20, and 21 were detected either through bidirectional sequencing or real-time polymerase chain reaction. Results: Among 812 patients in the study, 49% were female, 63.7% were ethnic Chinese, 29.4% Malay, 4.8% Indian, and 2.1% other ethnic groups. Mutations were present in the tumors of 321 patients (39.5%), with mutations at exons 19 (23.5%) and 21 (14.9%) being the most common. Mutations were significantly more frequent among women than in men (52.5% versus 27.8%, p < 0.001). Although mutations were more common among Chinese (40.8%) compared with Malay (37.2%) or Indian (33.3%) patients, the difference was not statistically significant (p = 0.591). Of 211 patients with smoking history records, never-smokers had a higher mutation rate compared with ever-smokers (54.8% versus 20.7%, p < 0.001). Conclusion: EGFR mutations were present in 39.5% of patients. Mutations were more common in women and never-smokers with no differences in mutation frequency between different ethnicities. Because of the high mutation rates, reflex testing for EGFR mutation should be a routine practice for advanced lung adenocarcinoma patients in Malaysia. Copyright ©2013 by the International Association for the Study of Lung Cancer.

Ramesh S.,University of Malaya | Shanti R.,University of Malaya | Morris E.,University Tunku Abdul Rahman
Carbohydrate Polymers | Year: 2013

Polymer electrolytes were developed by solution casting technique utilizing the materials of cellulose acetate (CA), lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) and deep eutectic solvent (DES). The DES is synthesized from the mixture of choline chloride and urea of 1:2 ratios. The increasing DES content well plasticizes the CA:LiTFSI:DES matrix and gradually improves the ionic conductivity and chemical integrity. The highest conducting sample was identified for the composition of CA:LiTFSI:DES (28 wt.%:12 wt.%:60 wt.%), which has the greatest ability to retain the room temperature ionic conductivity over the entire 30 days of storage time. The changes in FTIR cage peaks upon varying the DES content in CA:LiTFSI:DES prove the complexation. This complexation results in the collapse of CA matrix crystallinity, observed from the reduced intensity of XRD diffraction peaks. The DES-plasticized sample is found to be more heat-stable compared to pure CA. Nevertheless, the addition of DES diminishes the CA:LiTFSI matrix's heat-resistivity but at the minimum addition the thermal stability is enhanced. © 2012 Elsevier Ltd.

Letchumanan V.,Monash University | Letchumanan V.,University of Malaya | Chan K.-G.,University of Malaya | Lee L.-H.,Monash University
Frontiers in Microbiology | Year: 2014

Vibrio parahaemolyticus is a Gram-negative halophilic bacterium that is found in estuarine, marine and coastal environments. V. parahaemolyticus is the leading causal agent of human acute gastroenteritis following the consumption of raw, undercooked, or mishandled marine products. In rare cases, V. parahaemolyticus causes wound infection, ear infection or septicaemia in individuals with pre-existing medical conditions. V. parahaemolyticus has two hemolysins virulence factors that are thermostable direct hemolysin (tdh)-a pore-forming protein that contributes to the invasiveness of the bacterium in humans, and TDH-related hemolysin (trh), which plays a similar role as tdh in the disease pathogenesis. In addition, the bacterium is also encodes for adhesions and type III secretion systems (T3SS1 and T3SS2) to ensure its survival in the environment. This review aims at discussing the V. parahaemolyticus growth and characteristics, pathogenesis, prevalence and advances in molecular identification techniques. © 2014 Letchumanan, Chan and Lee.

Ramesh S.,University of Malaya | Lu S.-C.,University Tunku Abdul Rahman
Journal of Molecular Structure | Year: 2011

The X-ray Diffraction (XRD), Horizontal Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (HATR-FTIR) and Differential Scanning Calorimetry (DSC) have been employed to study the correlation between the concentration of lithium trifluoromethanesulfonate (LiTf) salt with the conversion of crystalline to amorphous nature in poly(vinylidene fluoride-co-hexafluoropropylene) [P(VdF-HFP)]. Results obtained from selected samples with low, intermediate and high concentrations of LiTf salt incorporated in P(VdF-HFP) suggest that the LiTf salt effectively reduces the degree of crystallinity in P(VdF-HFP)-based solid polymer electrolytes. The addition of LiTf to P(VdF-HFP) creates an interaction between cations and the fluorine atom of the copolymer. All the results corroborate each other and supported by impedance spectroscopy and photoluminescence studies (PL). This signifies that LiTf is well dissociated to complex with P(VdF-HFP). It effectively disrupts the crystalline domain and gives rise to new P(VdF-HFP)/LiTf amorphous phase. © 2011 Elsevier B.V. All rights reserved.

Ramesh S.,University of Malaya | Liew C.-W.,University Tunku Abdul Rahman | Ramesh K.,University of Malaya
Journal of Non-Crystalline Solids | Year: 2011

1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl imide), BmImTFSI based poly(methyl methacrylate)-poly (vinyl chloride), PMMA-PVC gel polymer electrolytes were prepared by solution casting technique. These ionic liquid-based gel polymer electrolytes exhibit Arrhenius type temperature dependence of ionic conductivity. The highest ionic conductivity of (8.08 ± 0.01) × 10- 4 Scm-1 was achieved at 80 °C upon addition of 60 wt.% of BmImTFSI. X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies revealed the amorphous nature and morphology of these polymer electrolytes, respectively. The lower coherence length of the peak inferred the higher amorphous degree in these polymer matrices. Decreases in Tg and Tm indicate the flexibility of polymer backbone. The amorphous behavior of these ionic liquid-based gel polymer electrolytes are also enhanced as shown in differential scanning calorimetry (DSC) analysis. On the contrary, thermogravimetric analysis (TGA) divulges that the thermal stability of polymer electrolytes has been improved upon impregnation of BmImTFSI. © 2011 Elsevier B.V. All rights reserved.

Varikoden H.,Indian Institute of Tropical Meteorology | Samah A.A.,University of Malaya | Babu C.A.,Cochin University of Science and Technology
Journal of Hydrology | Year: 2010

The present study is focused on the intensity distribution of rainfall in different classes and their contribution to the total seasonal rainfall. In addition, we studied the spatial and diurnal variation of the rainfall in the study areas. For the present study, we retrieved data from TRMM (Tropical Rain Measuring Mission) rain rate available in every 3 h temporal and 25 km spatial resolutions. Moreover, station rainfall data is used to validate the TRMM rain rate and found significant correlation between them (linear correlation coefficients are 0.96, 0.85, 0.75 and 0.63 for the stations Kota Bharu, Senai, Cameron highlands and KLIA, respectively). We selected four areas in the Peninsular Malaysia and they are south coastal, east coastal, west coastal and highland regions. Diurnal variation of frequency of rain occurrence is different for different locations. We noticed bimodal variation in the coastal areas in most of the seasons and unimodal variation in the highland/inland area. During the southwest monsoon period in the west coastal stations, there is no distinct diurnal variation. The distribution of different intensity classes during different seasons are explained in detail in the results. © 2010 Elsevier B.V.

Objective: Bacterial resistance to antibiotics is the single most important determinant of treatment success. The objective of this study was to determine the prevalence of Helicobacter pylori resistance to clarithromycin, amoxicillin, metronidazole, tetracycline, levofloxacin, rifabutin, and furazolidone in our local bacterial strains. Methods: Samples from consecutive ninety patients were obtained for culture and sensitivity testing. Resistance to individual antibiotics were tested using the E-test and MIC90 read from the strips. Resistance to rifampicin and nitrofurantoin were used as a surrogate for rifabutin and furazolidine. Results: There was a high prevalence of resistance to metronidazole 68/90 (75.5%). No male (34/45 (75.5%) versus female (35/45 (77.7%) difference in frequency of metronidazole resistance was noted (p=1.000). There was zero resistance 0 to clarithromycin, levofloxacin, amoxicillin, and nitrofurantoin/furazolidone. Resistance to rifampicin/rifabutin was for breakpoints of 1 and 4μg/mL of 14.4 and 2.2% respectively. Conclusions: Although there was high bacterial resistance to metronidazole, the absence of resistance particularly to the key antibiotics used in H. pylori eradication therapy: clarithromycin and levofloxacin is reassuring to note. Continued monitoring of antibiotic resistance should be carried out. © 2011 Blackwell Publishing Ltd.

Anderson B.O.,Fred Hutchinson Cancer Research Center | Cazap E.,SLACOM Sociedad Latinoamericana y del Caribe de Oncologia Medica | El Saghir N.S.,American University of Beirut | Yip C.-H.,University of Malaya | And 5 more authors.
The Lancet Oncology | Year: 2011

The purpose of the Breast Health Global Initiative (BHGI) 2010 summit was to provide a consensus analysis of breast cancer control issues and implementation strategies for low-income and middle-income countries (LMCs), where advanced stages at presentation and poor diagnostic and treatment capacities contribute to lower breast cancer survival rates than in high-income countries. Health system and patient-related barriers were identified that create common clinical scenarios in which women do not present for diagnosis until their cancer has progressed to locally advanced or metastatic stages. As countries progress to higher economic status, the rate of late presentation is expected to decrease, and diagnostic and treatment resources are expected to improve. Health-care systems in LMCs share many challenges including national or regional data collection, programme infrastructure and capacity (including appropriate equipment and drug acquisitions, and professional training and accreditation), the need for qualitative and quantitative research to support decision making, and strategies to improve patient access and compliance as well as public, health-care professional, and policy-maker awareness that breast cancer is a cost-effective, treatable disease. The biggest challenges identified for low-income countries were little community awareness that breast cancer is treatable, inadequate advanced pathology services for diagnosis and staging, and fragmented treatment options, especially for the administration of radiotherapy and the full range of systemic treatments. The biggest challenges identified for middle-resource countries were the establishment and maintenance of data registries, the coordination of multidisciplinary centres of excellence with broad outreach programmes to provide community access to cancer diagnosis and treatment, and the resource-appropriate prioritisation of breast cancer control programmes within the framework of existing, functional health-care systems. © 2011 Elsevier Ltd.

Palanisamy U.D.,Monash University | Ling L.T.,University of Malaya | Manaharan T.,University of Malaya | Appleton D.,University of Malaya
Food Chemistry | Year: 2011

Recently we confirmed the ability of ethanolic Nephelium lappaceum L. rind extract to act as anti-hyperglycemic agent. Geraniin, an ellagitannin, was identified as the major bioactive compound isolated from the ethanolic Nephelium lappaceum L. rind extract. In this study, we describe the rapid isolation of geraniin from the above plant. In addition to its extremely high anti-oxidant activity and low pro-oxidant capability, geraniin is seen to possess in vitro hypoglycemic activity (alpha-glucosidase inhibition: IC 50 = 0.92 μg/ml and alpha-amylase inhibition: IC 50 = 0.93 μg/ml), aldol reductase inhibition activity (IC 50 = 7 μg/ml) and has the ability to prevent the formation of advanced glycation end-products (AGE). Geraniin was observed to exhibit these properties at more significant levels compared to the positive controls acarbose (carbohydrate hydrolysis inhibitor), quercetin (aldol reductase inhibitor) and green tea (AGE inhibitor). Geraniin therefore, has the potential to be developed into an anti-hyperglycemic agent. Our findings also strongly support the use of a geraniin-standardised N. lappaceum extract in the management of hyperglycemia. © 2011 Elsevier Ltd. All rights reserved.

Loh S.Y.,University of Malaya | Packer T.,Curtin University Australia | Chinna K.,University of Malaya | Quek K.F.,Monash University
Journal of Cancer Survivorship | Year: 2013

Purpose: Patient self-management enables living with a chronic disease effectively. This study examines the effectiveness of a 4-week self-management programme to enable self-management of the numerous after-effects and with breast cancer as a chronic disease. Methods: Upon ethical approval, 147 multiethnic survivors (stages I-III breast cancer) received either a 4-week self-management intervention (n = 68) or usual care (n = 78) on a controlled clinical trial in a medical centre. The facilitator-led group intervention provides self-management support and skills for managing the medical, emotional and role tasks. Survivors completed the pre- and post-intervention measures on quality of life, distress and participation inventory. Results: Multiple analyses of covariance (adjusted for baseline measures) showed significant differences between groups [F(6, 129) = 2.26, p = 0.04 at post-test and F(6, 129) = 4.090, p < 0.001 at follow-up]. Post hoc analysis indicated significantly better outcome on all measures. At follow-up, the experimental group had a mean quality of life (QOL) score of 3.39 [CI = 1.37-5.42; p = 0.001] greater than the control. Conclusions: There is preliminary evidence that the 4-week self-management intervention enhance the QOL of women with breast cancer, by enabling them to better self-manage the numerous medical, emotional and role tasks. Further randomised trials are warranted. Implication for Cancer Survivors: Survivors receiving self-management programme report improved HRQL compared with those on usual care. Although time can attenuate the participation limitation and distress of survivors, self-management programmes could help to increase patients' self-efficacy for better self-management. © 2013 Springer Science+Business Media New York.

Kazi S.N.,University of Malaya | Duffy G.G.,University of Auckland | Chen X.D.,Monash University
Desalination | Year: 2012

An apparatus was built to study heat transfer fouling on different heat exchanger pipe surfaces by visually observing the progressive fouling deposition under the same solution conditions. Test pipes were centrally located in a cylindrical tank with a concentric vertical agitator to give constant and uniform flow conditions near the pipe surface. Pipes with either smooth or roughened surfaces provided quantitative data on the progressive build-up and the composition of the deposits. The calcium sulphate deposition on four different metal surfaces (copper, aluminium, brass, and stainless steel) was investigated. The results show that fouling increases with time but at a decreasing rate over set intervals. The deposition also increases with the increasing thermal conductivity of the metal, or the total surface energy. Chemical reaction fouling along with particulate and crystallisation fouling occurred on reactive surfaces when corrosive chemicals were used, and this was compared with crystallisation-only fouling on non-reactive surfaces. Bleached Kraft softwood pulp fibres at various concentrations were added to the fouling solution to study their affects on fouling on the hydraulically smooth pipes. Fouling was retarded with only a low fibre concentration and reduced further as fibre concentration was increased. © 2012 Elsevier B.V.

Pramanik S.,University of Malaya | Pingguan-Murphy B.,University of Malaya | Cho J.,Inje University | Osman N.A.A.,University of Malaya
Scientific Reports | Year: 2014

The complex architecture of the cortical part of the bovine-femur was examined to develop potential tissue engineering (TE) scaffolds. Weight-change and X-ray diffraction (XRD) results show that significant phase transformation and morphology conversion of the bone occur at 500-750°C and 750-900°C, respectively. Another breakthrough finding was achieved by determining a sintering condition for the nucleation of hydroxyapatite crystal from bovine bone via XRD technique. Scanning electron microscopy results of morphological growth suggests that the concentration of polymer fibrils increases (or decreases, in case of apatite crystals) from the distal to proximal end of the femur. Energy-dispersive analysis of X-ray, Fourier transform infrared, micro-computer tomography, and mechanical studies of the actual composition also strongly support our microscopic results and firmly indicate the functionally graded material properties of bovine-femur. Bones sintered at 900 and 1000°C show potential properties for soft and hard TE applications, respectively.

Apergis N.,University of Piraeus | Tang C.F.,University of Malaya
Energy Economics | Year: 2013

The energy-growth literature contains a large number of discussions on the causal relationship between energy consumption and economic growth. The central debate focuses on whether energy consumption contributes or not to economic growth since it has direct implications for the formulation of strategic policies. Nevertheless, current studies cannot provide a conclusive suggestion due to mixed causality results. This inconclusive evidence is potentially attributed to model specifications and the stage of economic development of the countries under investigation. Hence, this study attempts to empirically re-investigate the validity of the energy-led growth hypothesis using a different model specification and different stages of economic development for 85 selected countries around the globe. Overall, although the causality results are mixed among countries, we do find a systematic pattern. In particular, Granger causality models with three and four variables are more likely to support the hypothesis compared to their counterparts that contain only two variables. In addition, both developed and developing countries are more likely to support the energy-led growth hypothesis compared to the less developed or low income countries. Therefore, causality results are very sensitive to the choice of the model specification along with the stages of economic development. Finally, energy conservation policies should only focus on low income countries as these policies may not retard the process of economic growth. © 2013 Elsevier B.V.

Palmer A.J.,University of Aberdeen | Ho C.K.M.,University of Malaya | Ajibola O.,University of Aberdeen | Avenell A.,University of Aberdeen
Critical Care Medicine | Year: 2013

OBJECTIVE:: To determine whether the supplementation of parenteral nutrition with ω-3 fatty acids confers treatment benefits to critically ill adult patients. DATA SOURCE:: We performed computerized searches for relevant articles from 1996 to June 2011 on MEDLINE, EMBASE, and the Cochrane register of controlled trials and abstracts of scientific meetings from 2005 to 2011. STUDY SELECTION:: Randomized controlled trials of ω-3 fatty acid supplemented parenteral nutrition in critically ill adult patients admitted to the intensive therapy unit, given in addition to their routine care, compared with parenteral nutrition without ω-3 fatty acid supplementation. DATA SYNTHESIS:: Five fully published trials and three trials published in abstract form with 391 participants have been included. Overall trial quality was poor. Mortality data were pooled from eight studies with 391 participants. No differences were found with a risk ratio for death of 0.83 (95% confidence interval 0.57, 1.20; p = 0.32). Data for infectious complications were available from five studies with 337 participants. No differences were found, with a risk ratio for infection of 0.78 (95% confidence interval 0.43, 1.41; p = 0.41). Data for intensive therapy unit and hospital length of stay were available from six and three studies with 305 and 117 participants, respectively. With respect to intensive therapy unit length of stay, no differences were observed with a mean difference of 0.57 days in favor of the ω-3 fatty acid group (95% confidence interval-5.05, 3.90; p = 0.80). A significant reduction in hospital length of stay of 9.49 days (95% confidence interval-16.51,-2.47; p = 0.008) was observed for those receiving ω-3 fatty acid supplemented parenteral nutrition, but results were strongly influenced by one small study. CONCLUSIONS:: On the basis of this systematic review, it can be concluded that ω-3 fatty acid supplementation of parenteral nutrition does not improve mortality, infectious complications, and intensive therapy unit length of stay in comparison with standard parenteral nutrition. Although ω-3 fatty acids appear to reduce hospital length of stay, the poor methodology of the included studies and the absence of other outcome improvements mean they cannot be presently recommended. © 2013 by the Society of Critical Care Medicine and Lippincott Williams & Wilkins.

Zilany M.S.A.,University of Malaya | Bruce I.C.,McMaster University | Carney L.H.,University of Rochester
Journal of the Acoustical Society of America | Year: 2014

A phenomenological model of the auditory periphery in cats was previously developed by Zilany and colleagues [J. Acoust. Soc. Am. 126, 2390-2412 (2009)] to examine the detailed transformation of acoustic signals into the auditory-nerve representation. In this paper, a few issues arising from the responses of the previous version have been addressed. The parameters of the synapse model have been readjusted to better simulate reported physiological discharge rates at saturation for higher characteristic frequencies [Liberman, J. Acoust. Soc. Am. 63, 442-455 (1978)]. This modification also corrects the responses of higher-characteristic frequency (CF) model fibers to low-frequency tones that were erroneously much higher than the responses of low-CF model fibers in the previous version. In addition, an analytical method has been implemented to compute the mean discharge rate and variance from the model's synapse output that takes into account the effects of absolute refractoriness. © 2014 Acoustical Society of America.

Sarhan A.A.D.,University of Malaya | Sarhan A.A.D.,Assiut University
International Journal of Advanced Manufacturing Technology | Year: 2014

As the demand for high speed and highly accurate machines has significantly increased, error motions from thermal change, which is up to 70 % of the total machining error, is found to be the main hurdles to overcome in improving the accuracy of CNC machine tools. In this research work, the authors installed four eddy current displacement sensors in the spindle structure near to the front bearing to monitor the spindle offset in the bearing level, which is mainly attributable to the thermal error motions of the spindle. In addition, another three capacitance sensors are mounted on the machine table level and aligned with the x-, y-, and z-axis of the machine to monitor the spindle shift in the table level to find out the correlation between temperature change and the thermal error motions of the spindle. To measure the temperature changes, we attached thermal sensors in the machine and cooling system. The estimation of the spindle thermal displacement based on temperature data from these thermal sensors can provide more information for the monitoring of thermal error motions of the spindle. © 2013 Springer-Verlag London.

Ahmad M.Y.,University of Technology, Sydney | Ahmad M.Y.,University of Malaya | Mohan A.S.,University of Technology, Sydney
IEEE Transactions on Industrial Electronics | Year: 2014

We propose a novel method of positioning using a high-frequency radio-frequency identification (HF RFID) system for navigating autonomous vehicles when a sparse grid of floor tags is employed. For this, we propose a novel triangular multiloop-bridge reader antenna which generates an error signal in the form of bridge potential that is a function of the tags' location. The proposed positioning algorithm combines the information from the reader database with the error signals generated by the bridge loop and couples them with any available data from the wheel encoders of an autonomously moving object to deduce its position and orientation. The accuracy and efficacy of the proposed algorithm are evaluated using both simulations and experiments using an autonomous wheelchair. The results indicate that the proposed method offers a significant improvement over existing HF-RFID-based positioning methods for larger floor-tag-grid separation. © 1982-2012 IEEE.

Kothari R.,Babasaheb Bhimrao Ambedkar University | Singh D.P.,Babasaheb Bhimrao Ambedkar University | Tyagi V.V.,University of Malaya | Tyagi S.K.,Sardar Swaran Singh National Institute of Renewable Energy
Renewable and Sustainable Energy Reviews | Year: 2012

Hydrogen generation from wastewater is one of the promising approaches through biological route. So, exploitation of wastewater as substrate for hydrogen production with concurrent wastewater treatment is an attractive and effective way of tapping clean energy from renewable resources in a sustainable approach. In this direction, considerable interest is observed on various biological routes of hydrogen production using bio-photolysis, photo fermentation and heterotrophic dark fermentation process or by a combination of these processes. Therefore, in this communication, utilizing industrial wastewater as primary substrate for dark fermentation process is reviewed and different parametric aspects associated with this sustainable approach for better energy production is discussed. The industrial wastewaters that could be the source for bio hydrogen generation, such as rice slurry wastewater, food and domestic wastewaters, citric acid wastewater and paper mill wastewater, are also discussed in this article. © 2012 Elsevier Ltd. All rights reserved.

Unar J.A.,University of Malaya | Unar J.A.,University for Information Science and Technology | Seng W.C.,University of Malaya | Abbasi A.,University of Malaya
Pattern Recognition | Year: 2014

Identity management through biometrics offer potential advantages over knowledge and possession based methods. A wide variety of biometric modalities have been tested so far but several factors paralyze the accuracy of mono-modal biometric systems. Usually, the analysis of multiple modalities offers better accuracy. An extensive review of biometric technology is presented here. Besides the mono-modal systems, the article also discusses multi-modal biometric systems along with their architecture and information fusion levels. The paper along with the exemplary evidences highlights the potential for biometric technology, market value and prospects. © 2014 Elsevier Ltd.

Abdul-Rahman S.-S.,University of Malaya | Du Boulay B.,University of Sussex
Computers in Human Behavior | Year: 2014

This paper describes an experiment that compared learners with contrasting learning styles, Active vs. Reflective, using three different strategies for learning programming via worked-examples: Paired-method, Structure-emphasising, and Completion. The quality of the learners' acquired cognitive schemata was assessed in terms of their post-test performance. The experiment investigated variations in learners' cognitive load, taking both the learning strategies and the learners' learning styles into account. Overall, the results of the experiment were inconsistent. In comparing the effects of the strategies during the learning phase, the study found significant differences in cognitive load. Unexpectedly, no differences were then detected either in cognitive load or in performance during the post-test (post-test). In comparing the effects of the learning styles during the learning phase and the transfer phase, medium effect sizes suggested that learning style may have had an effect on cognitive load. However, no significant difference was observed in performance during the post-test. © 2013 Elsevier B.V. All rights reserved.

Nissapatorn V.,University of Malaya | Sawangjaroen N.,Prince of Songkla University
Indian Journal of Medical Research | Year: 2011

After 30 years of the human immunodeficiency virus (HIV) epidemic, parasites have been one of the most common opportunistic infections (OIs) and one of the most frequent causes of morbidity and mortality associated with HIV-infected patients. Due to severe immunosuppression, enteric parasitic pathogens in general are emerging and are OIs capable of causing diarrhoeal disease associated with HIV. Of these, Cryptosporidium parvum and Isospora belli are the two most common intestinal protozoan parasites and pose a public health problem in acquired immunodeficiency syndrome (AIDS) patients. These are the only two enteric protozoan parasites that remain in the case definition of AIDS till today. Leismaniasis, strongyloidiasis and toxoplasmosis are the three main opportunistic causes of systemic involvements reported in HIV-infected patients. Of these, toxoplasmosis is the most important parasitic infection associated with the central nervous system. Due to its complexity in nature, toxoplasmosis is the only parasitic disease capable of not only causing focal but also disseminated forms and it has been included in AIDS-defining illnesses (ADI) ever since. With the introduction of highly active anti-retroviral therapy (HAART), cryptosporidiosis, leishmaniasis, schistosomiasis, strongyloidiasis, and toxoplasmosis are among parasitic diseases reported in association with immune reconstitution inflammatory syndrome (IRIS). This review addresses various aspects of parasitic infections in term of clinical, diagnostic and therapeutic challenges associated with HIV-infection.

Alao A.-R.,University of Malaya | Konneh M.,International Islamic University Malaysia
International Journal of Advanced Manufacturing Technology | Year: 2012

Conventional grinding of silicon substrates results in poor surface quality unless they are machined in ductile mode on expensive ultra-precision machine tools. However, precision grinding can be used to generate massive ductile surfaces on silicon so that the polishing time can be reduced immensely and surface quality improved. However, precision grinding has to be planned with reliability in advance and the process has to be performed with high rates of reproducibility. Therefore, this work reports the empirical models developed for surface parameters R a, R max, and R t with precision grinding parameters, depths of cut, feed rates, and spindle speeds using conventional numerical control machine tools with Box-Behnken design. Second-order models are developed for the surface parameters in relation to the grinding parameters. Analysis of variance is used to show the parameters as well as their interactions that influence the roughness models. The models are capable of navigating the design space. Also, the results show large amounts of ductile streaks at depth of cut of 20 μm, feed rate of 6.25 mm/min, and spindle speed of 70,000 rpm with a 43-nm R a. Optimization experiments by desirability function generate 37-nm R a, 400-nm R max, and 880-nm R t with massive ductile surfaces. © 2011 Springer-Verlag London Limited.

Mishima T.,Kobe University | Takami C.,Kobe University | Nakaoka M.,Kyungnam University | Nakaoka M.,University of Malaya | Nakaoka M.,Yamaguchi University
IEEE Transactions on Industrial Electronics | Year: 2014

A novel soft-switching high-frequency (HF) resonant (HF-R) inverter for induction heating (IH) applications is presented in this paper. By adopting the current phasor control of changing a phase shift (PS) angle between two half-bridge inverter units, the IH load resonant current can be regulated continuously under the condition of wide-range soft-switching operations. In addition to this, the dual-mode power regulation scheme-based PS angle control and asymmetrical pulsewidth modulation in one inverter unit is proposed for improving the efficiency in low output power settings. The essential performances on the output power regulation and soft-switching operations are demonstrated in an experiment using its 1-kW 60-kHz HF-R inverter prototype, and then, the topological validity is evaluated from a practical point of view. © 2013 IEEE.

Keshavarz Moraveji M.,Arak University | Mohammadi Ardehali R.,Arak University | Ijam A.,University of Malaya
International Communications in Heat and Mass Transfer | Year: 2013

For improvement in information technology (IT), removing heat from electrical devices is an important factor, and current activities try to investigate (numerically, experimentally) new methods of thermal load managing. Mini-channel liquid cooling is one of the candidates for this purpose. Nanofluid as an innovative heat-transfer fluid was used in mini-channel heat sink. Modeling analyzed in this study is a mini-channel heat sink with 20×20mm bottom. For this purpose, five nanoparticle volume fractions namely 0.8, 1.6, 2.4, 3.2 and 4% in five inlet velocities for both types of nanoparticle containing TiO2 and SiC were used. Furthermore, effect of a nanoparticle volume fraction on the convective heat transfer coefficient was investigated in different Reynolds numbers. Modeling results were compared with reference analytical calculations. In addition according to the modeling results, correlated equations were obtained for Nusselt number and friction factor, and its accuracies were acceptable. © 2012 Elsevier Ltd.

Xi Z.,Harvard University | Wang Y.,Fudan University | Bradley R.K.,Fred Hutchinson Cancer Research Center | Sugumaran M.,University of Malaya | And 3 more authors.
PLoS Genetics | Year: 2013

Recent studies have suggested that plant genomes have undergone potentially rampant horizontal gene transfer (HGT), especially in the mitochondrial genome. Parasitic plants have provided the strongest evidence of HGT, which appears to be facilitated by the intimate physical association between the parasites and their hosts. A recent phylogenomic study demonstrated that in the holoparasite Rafflesia cantleyi (Rafflesiaceae), whose close relatives possess the world's largest flowers, about 2.1% of nuclear gene transcripts were likely acquired from its obligate host. Here, we used next-generation sequencing to obtain the 38 protein-coding and ribosomal RNA genes common to the mitochondrial genomes of angiosperms from R. cantleyi and five additional species, including two of its closest relatives and two host species. Strikingly, our phylogenetic analyses conservatively indicate that 24%-41% of these gene sequences show evidence of HGT in Rafflesiaceae, depending on the species. Most of these transgenic sequences possess intact reading frames and are actively transcribed, indicating that they are potentially functional. Additionally, some of these transgenes maintain synteny with their donor and recipient lineages, suggesting that native genes have likely been displaced via homologous recombination. Our study is the first to comprehensively assess the magnitude of HGT in plants involving a genome (i.e., mitochondria) and a species interaction (i.e., parasitism) where it has been hypothesized to be potentially rampant. Our results establish for the first time that, although the magnitude of HGT involving nuclear genes is appreciable in these parasitic plants, HGT involving mitochondrial genes is substantially higher. This may represent a more general pattern for other parasitic plant clades and perhaps more broadly for angiosperms. © 2013 Xi et al.

Zaharan N.L.,University of Malaya | Williams D.,Royal College of Surgeons in Ireland | Bennett K.,St James's Hospital
British Journal of Clinical Pharmacology | Year: 2013

Aims: (i) To examine the incidence of new onset treated diabetes in patients treated with different types of statins and (ii) the relationship between the duration and dose of statins and the subsequent development of new onset treated diabetes. Methods: A retrospective cohort study was performed using the Irish Health Services Executive Primary Care Reimbursement Services national pharmacy claims database. Individuals who received any medicines were identified from January 2001 to January 2009 (n = 1235671). Patients newly treated with statins from 1 January 2002 to 31 December 2007 were identified (n = 239628). Cases were identified as individuals newly treated with antidiabetic medication (n = 38503). Adjusted hazards ratios (HR) with 95% confidence intervals (CI) were calculated to examine the association between statins (any vs. none) and time to new onset treated diabetes using Cox proportional hazard regression. The dose and duration response relationship between statins and new onset treated diabetes was examined using restricted spline functions to assess the linearity of the relationship. Results: Statin use was associated with an increased risk of new onset treated diabetes (HR = 1.18, 95% CI 1.15, 1.22). Increased risk of new onset treated diabetes was found with rosuvastatin (HR = 1.41, 95% CI 1.31, 1.52), atorvastatin (HR = 1.23, 95% CI 1.19, 1.27) and simvastatin (HR = 1.15, 95% CI 1.05, 1.25). There were statistically significant overall dose and duration effects for all statins, excepting fluvastatin, which only demonstrated a duration effect. Conclusion: An increased risk of new onset treated diabetes was found in those treated with statins showing significant duration and dose effect. Further study is required to confirm this association. © 2012 The British Pharmacological Society.

Shahid S.,University of Malaya | Hazarika M.K.,Asian Institute of Technology
Water Resources Management | Year: 2010

Prolonged absence of groundwater within the operating range of shallow tube-wells during dry season is a common problem in the northwestern districts of Bangladesh in the recent years. In this paper, groundwater scarcity and drought in three northwestern districts of Bangladesh have been investigated. The Cumulative Deficit approach from a threshold groundwater level has been used for the computation of severity of groundwater droughts. Monthly groundwater fluctuation data collected from 85 sites is used for the study. The study shows that groundwater scarcity in 42% area is an every year phenomenon in the region. Analysis of groundwater hydrographs and rainfall time-series reveals that ever increasing groundwater extraction for irrigation in the dry season and recurrent droughts are the causes of groundwater level drop in the region. © 2009 Springer Science+Business Media B.V.

Hoskin A.W.,University of Texas of the Permian Basin | Ellis L.,University of Malaya
Criminology | Year: 2015

Evolutionary neuroandrogenic (ENA) theory asserts that criminality is a crude form of competitive behavior over resources, status, and mating opportunities. Theoretically, males have been selected for resource acquisitiveness as a result of female preferences for mates who are successful at resource provisioning. ENA theory also asserts that brain exposure to both prenatal and postpubertal androgens (particularly testosterone) promotes all forms of competitiveness, including those that victimize others. The present study was undertaken to test ENA theory by correlating 14 self-reported measures of offending with a biomarker for fetal testosterone exposure based on the ratio of the 2nd and 4th digits of the right hand (r2D:4D), in a nonrepresentative sample of 445. Both Spearman correlations and negative binomial regressions produced results that largely supported the hypothesized connection between offending and high prenatal androgen exposure, even when findings were analyzed separately by sex. Also, offending was significantly associated with r2D:4D for both males and females. Overall, this study supports the view that exposing the brain to high levels of testosterone and other androgens prenatally elevates the probability of offending later in life. © 2014 American Society of Criminology.

Azad H.B.,University of Malaya | Mekhilef S.,University of Malaya | Ganapathy V.G.,SRM University
IEEE Transactions on Sustainable Energy | Year: 2014

Long-term forecasting of wind speed has become a research hot spot in many different areas such as restructured electricity markets, energy management, and wind farm optimal design. However, wind energy with unstable and intermittent characteristics entails establishing accurate predicted data to avoid inefficient and less reliable results. The proposed study in this paper may provide a solution regarding the long-term wind speed forecast in order to solve the earlier-mentioned problems. For this purpose, two fundamentally different approaches, the statistical and the neural network-based approaches, have been developed to predict hourly wind speed data of the subsequent year. The novelty of this study is to forecast the general trend of the incoming year by designing a data fusion algorithm through several neural networks. A set of recent wind speed measurement samples from two meteorological stations in Malaysia, namely Kuala Terengganu and Mersing, are used to train and test the data set. The result obtained by the proposed method has given rather promising results in view of the very small mean absolute error (MAE). © 2010-2012 IEEE.

Vockerodt M.,University of Birmingham | Yap L.-F.,University of Malaya | Shannon-Lowe C.,University of Birmingham | Curley H.,University of Birmingham | And 3 more authors.
Journal of Pathology | Year: 2015

Since the discovery in 1964 of the Epstein-Barr virus (EBV) in African Burkitt lymphoma, this virus has been associated with a remarkably diverse range of cancer types. Because EBV persists in the B cells of the asymptomatic host, it can easily be envisaged how it contributes to the development of B-cell lymphomas. However, EBV is also found in other cancers, including T-cell/natural killer cell lymphomas and several epithelial malignancies. Explaining the aetiological role of EBV is challenging, partly because the virus probably contributes differently to each tumour and partly because the available disease models cannot adequately recapitulate the subtle variations in the virus-host balance that exist between the different EBV-associated cancers. A further challenge is to identify the co-factors involved; because most persistently infected individuals will never develop an EBV-associated cancer, the virus cannot be working alone. This article will review what is known about the contribution of EBV to lymphoma development. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Ellis L.,University of Malaya | Hoskin A.W.,University of Texas of the Permian Basin
International Journal of Offender Therapy and Comparative Criminology | Year: 2015

A decade old theory hypothesizes that brain exposure to androgens promotes involvement in criminal behavior. General support for this hypothesis has been provided by studies of postpubertal circulating levels of testosterone, at least among males. However, the theory also predicts that for both genders, prenatal androgens will be positively correlated with persistent offending, an idea for which no evidence currently exists. The present study used an indirect measure of prenatal androgen exposure - the relative length of the second and fourth fingers of the right hand (r2D:4D) - to test the hypothesis that elevated prenatal androgens promote criminal tendencies later in life for males and females. Questionnaires were administered to 2,059 college students in Malaysia and 1,291 college students in the United States. Respondents reported their r2D:4D relative finger lengths along with involvement in 13 categories of delinquent and criminal acts. Statistically significant correlations between the commission of most types of offenses and r2D:4D ratios were found for males and females even after controlling for age. It is concluded that high exposure to androgens during prenatal development contributes to most forms of offending following the onset of puberty. © The Author(s) 2013.

Zainol M.I.,University of Malaya | Mohd Yusoff K.,Canik Basari University | Mohd Yusof M.Y.,University of Malaya
BMC Complementary and Alternative Medicine | Year: 2013

Background: Antibacterial activity of honey is mainly dependent on a combination of its peroxide activity and non-peroxide components. This study aims to investigate antibacterial activity of five varieties of Malaysian honey (three monofloral; acacia, gelam and pineapple, and two polyfloral; kelulut and tualang) against Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Pseudomonas aeruginosa.Methods: Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were performed for semi-quantitative evaluation. Agar well diffusion assay was used to investigate peroxide and non-peroxide activities of honey.Results: The results showed that gelam honey possessed lowest MIC value against S. aureus with 5% (w/v) MIC and MBC of 6.25% (w/v). Highest MIC values were shown by pineapple honey against E. coli and P. aeruginosa as well as acacia honey against E. coli with 25% (w/v) MIC and 50% (w/v) MBC values. Agar inhibition assay showed kelulut honey to possess highest total antibacterial activity against S. aureus with 26.49 equivalent phenol concentrations (EPC) and non-peroxide activity of 25.74 EPC. Lowest antibacterial activity was observed in acacia honey against E. coli with total activity of 7.85 EPC and non-peroxide activity of 7.59 EPC. There were no significant differences (p > 0.05) between the total antibacterial activities and non-peroxide activities of Malaysian honey. The intraspecific correlation between MIC and EPC of E. coli (r = -0.8559) was high while that between MIC and EPC of P. aeruginosa was observed to be moderate (r = -0.6469). S. aureus recorded a smaller correlation towards the opposite direction (r = 0.5045). In contrast, B.cereus showed a very low intraspecific correlation between MIC and EPC (r = -0.1482).Conclusions: Malaysian honey, namely gelam, kelulut and tualang, have high antibacterial potency derived from total and non-peroxide activities, which implies that both peroxide and other constituents are mutually important as contributing factors to the antibacterial property of honey. © 2013 Zainol et al.; licensee BioMed Central Ltd.

Gholami R.,Aston University | Sulaiman A.B.,University of Malaya | Ramayah T.,USM | Molla A.,RMIT University
Information and Management | Year: 2013

Based on a Belief-Action-Outcome framework, we produced a model that shows senior managers' perception of both the antecedents to and the consequences of Green IS adoption by a firm. This conceptual model and its associated hypotheses were empirically tested using a dataset generated from a survey of 405 organizations. The results suggest that coercive pressure influences the attitude toward Green IS adoption while mimetic pressure does not. In addition, we found that there was a significant relationship between Green IS adoption, attitude, and consideration of future consequences. Finally, we found that only long term Green IS adoption was positively related to environmental performance. © 2013 Elsevier B.V.

Lim S.-Y.,Toronto Western Hospital | Lim S.-Y.,University of Malaya | Lang A.E.,Toronto Western Hospital
Movement Disorders | Year: 2010

Nonmotor symptoms (NMS) are very common in Parkinson's disease (PD) and may result in significant disability. The increased focus on these important clinical features represents a major advance in the care of PD patients. In this article, we provide an overview of recent developments in the field. © 2010 Movement Disorder Society.

Tan M.P.,University of Malaya | Morgan K.,Royal College of Surgeons in Ireland
Current Opinion in Psychiatry | Year: 2015

Purpose of review. To evaluate recent literature on psychological interventions in cardiovascular disease. Recent findings. Mindfulness-based stress reduction did not reduce blood pressure, and a self-management programme in heart failure patients (HART), showed no improvement in health-related quality of life. Web-based decision aids are as effective as individually tailored counseling at reducing cardiovascular risk. Among health attack survivors, the ProActive Heart study involving telephone delivered counseling reduced anxiety whereas integrated motivational interviewing cognitive behavioral therapy (Beating Heart Problems) reduced depression and anger with no physiological or behavioral benefits. Summary. Psychological conditions increase cardiovascular risk as well as complicate cardiovascular disease. Psychological interventions are, however, far less studied compared with pharmacological and device therapies for cardiovascular disease. Interventions can either be delivered in isolation or in combination with other interventions including education, exercise, and medications, whereas outcomes measured could include psychometrics, behavior, risk scores, cardiovascular endpoints, and mortality. Due to the large variety of possible interventions and outcomes, published studies have reported mixed results and it remains unclear which modes of delivery and which types of intervention are most appropriate. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.

Shabaruddin F.H.,University of Malaya | Chen L.-C.,University of Nottingham | Elliott R.A.,University of Nottingham | Payne K.,University of Manchester
PharmacoEconomics | Year: 2013

Background: Chemotherapy offers cancer patients the potential benefits of improved mortality and morbidity but may cause detrimental outcomes due to adverse drug events (ADEs), some of which requiring time-consuming, resource-intensive and costly clinical management. To appropriately assess chemotherapy agents in an economic evaluation, ADE-related parameters such as the incidence, (dis)utility and cost of ADEs should be reflected within the model parameters. To date, there has been no systematic summary of the existing literature that quantifies the utilities of ADEs due to healthcare interventions in general and chemotherapy treatments in particular. Objective: This review aimed to summarize the current evidence base of reported utility values for chemotherapy-related ADEs. Methods: A structured electronic search combining terms for utility, utility valuation methods and generic terms for cancer treatment was conducted in MEDLINE and EMBASE in June 2011. Inclusion criteria were: (1) elicitation of utility values for chemotherapy-related ADEs and (2) primary data. Two reviewers identified studies and extracted data independently. Any disagreements were resolved by a third reviewer. Results: Eighteen studies met the inclusion criteria from the 853 abstracts initially identified, collectively reporting 218 utility values for chemotherapy-related ADEs. All 18 studies used short descriptions (vignettes) to obtain the utility values, with nine studies presenting the vignettes used in the valuation exercises. Of the 218 utility values, 178 were elicited using standard gamble (SG) or time trade-off (TTO) approaches, while 40 were elicited using visual analogue scales (VAS). There were 169 utility values of specific chemotherapy-related ADEs (with the top ten being anaemia [34 values], nausea and/or vomiting [32 values], neuropathy [21 values], neutropenia [12 values], diarrhoea [12 values], stomatitis [10 values], fatigue [8 values], alopecia [7 values], hand-foot syndrome [5 values] and skin reaction [5 values]) and 49 of non-specific chemotherapy-related adverse events. In most cases, it was difficult to directly compare the utility values as various definitions and study-specific vignettes were used for the ADEs of interest. Limitations: This review was designed to provide an overall description of existing literature reporting utility values for chemotherapy-related ADEs. The findings were not exhaustive and were limited to publications that could be identified using the search strategy employed and those reported in the English language. Conclusions: This review identified wide ranges in the utility values reported for broad categories of specific chemotherapy-related ADEs. There were difficulties in comparing the values directly as various study-specific definitions were used for these ADEs and most studies did not make the vignettes used in the valuation exercises available. It is recommended that a basic minimum requirement be developed for the transparent reporting of study designs eliciting utility values, incorporating key criteria such as reporting how the vignettes were developed and presenting the vignettes used in the valuation tasks as well as valuing and reporting the utility values of the ADE-free base states. It is also recommended, in the future, for studies valuing the utilities of chemotherapy-related ADEs to define the ADEs according to the National Cancer Institute (NCI) definitions for chemotherapy-related ADEs as the use of the same definition across studies would ease the comparison and selection of utility values and make the overall inclusion of adverse events within economic models of chemotherapy agents much more straightforward. © 2013 Springer International Publishing Switzerland.

Moradi Golsheikh A.,University of Malaya | Huang N.M.,University of Malaya | Lim H.N.,University Putra Malaysia | Zakaria R.,University of Malaya | Yin C.-Y.,Murdoch University
Carbon | Year: 2013

Silver-nanoparticles-decorated reduced graphene oxide (rGO) was electrodeposited on indium tin oxide (ITO) by a cyclic voltammetry method. The results of X-ray diffraction, Fourier-transform infrared transmission spectroscopy and Raman spectroscopy confirmed the simultaneous formation of cubic phase silver nanoparticles and reduction of GO through the electrodeposition process. Field emission scanning electron microscope images showed a uniform distribution of nanometer-sized silver nanoparticles with a narrow size distribution on the RGO sheets, which could only be achieved using silver ammonia complex instead of silver nitrate as precursor. The composite deposited on ITO exhibited notable electrocatalytic activity for the reduction of H2O2, leading to an enzymeless electrochemical sensor with a fast amperometric response time less than 2 s. The corresponding calibration curve of the current response showed a linear detection range of 0.1-100 mM (R2 = 0.9992) while the limit of detection was estimated to be 5 μM. © 2013 Elsevier Ltd. All rights reserved.

Skyllas-Kazacos M.,University of New South Wales | Chakrabarti M.H.,University of Malaya | Hajimolana S.A.,University of Malaya | Mjalli F.S.,Sultan Qaboos University | Saleem M.,Karachi Institute of Power Engineering
Journal of the Electrochemical Society | Year: 2011

The past few decades have shown a rapid and continuous exhaustion of the available energy resources which may lead to serious energy global crises. Researchers have been focusing on developing new and renewable energy resources to meet the increasing fuel demand and reduce greenhouse gas emissions. A surge of research effort is also being directed towards replacing fossil fuel based vehicles with hybrid and electric alternatives. Energy storage is now seen as a critical element in future smart grid and electric vehicle applications. Electrochemical energy storage systems offer the best combination of efficiency, cost and flexibility, with redox flow battery systems currently leading the way in this aspect. In this work, a panoramic overview is presented for the various redox flow battery systems and their hybrid alternatives. Relevant published work is reported and critically discussed. A comprehensive study of the available technologies is conducted in terms of technical aspects as well as economic and environmental consequences. Some of the flow battery limitations and technical challenges are also discussed and a range of further research opportunities are presented. Of the flow battery technologies that have been investigated, the all-vanadium redox flow battery has received the most attention and has shown most promise in various pre-commercial to commercial stationary applications to date, while new developments in hybrid redox fuel cells are promising to lead the way for future applications in mechanically and electrically refuelable electric vehicles. © 2011 The Electrochemical Society.

Mokhlis H.,University of Malaya | Li H.,University of Malaya | Li H.,University of Manchester
International Journal of Electrical Power and Energy Systems | Year: 2011

Fault location for distribution networks with multiple laterals would requires additional information such as from fault indicators and protective devices. As SCADA systems to provide such information are limited in 11 kV or lower voltage distribution networks, effective fault location method that only use information from a measurement at primary substation is needed. This paper presents the application of calculated non-linear voltage sag profiles and voltage sag measurement at primary substation to locate a fault in distribution networks. The proposed method firstly identifies the faulted section. From the indentified section, fault distance is calculated. The method has been tested under different fault scenarios that include various fault resistance, loading variation and data measurement errors. The results indicate the possibility of using this method to support automatic fault management system. © 2010 Elsevier Ltd. All rights reserved.

Ambati R.R.,University of Malaya | Moi P.S.,University of Malaya | Ravi S.,Indian Central Food Technological Research Institute | Aswathanarayana R.G.,Dayananda Sagar Institutions
Marine Drugs | Year: 2014

There is currently much interest in biological active compounds derived from natural resources, especially compounds that can efficiently act on molecular targets, which are involved in various diseases. Astaxanthin (3,3′-dihydroxy-β, β′ -carotene-4,4′-dione) is a xanthophyll carotenoid, contained in Haematococcus pluvialis, Chlorella zofingiensis, Chlorococcum, and Phaffia rhodozyma. It accumulates up to 3.8% on the dry weight basis in H. pluvialis. Our recent published data on astaxanthin extraction, analysis, stability studies, and its biological activities results were added to this review paper. Based on our results and current literature, astaxanthin showed potential biological activity in in vitro and in vivo models. These studies emphasize the influence of astaxanthin and its beneficial effects on the metabolism in animals and humans. Bioavailability of astaxanthin in animals was enhanced after feeding Haematococcus biomass as a source of astaxanthin. Astaxanthin, used as a nutritional supplement, antioxidant and anticancer agent, prevents diabetes, cardiovascular diseases, and neurodegenerative disorders, and also stimulates immunization. Astaxanthin products are used for commercial applications in the dosage forms as tablets, capsules, syrups, oils, soft gels, creams, biomass and granulated powders. Astaxanthin patent applications are available in food, feed and nutraceutical applications. The current review provides up-to-date information on astaxanthin sources, extraction, analysis, stability, biological activities, health benefits and special attention paid to its commercial applications. © 2014 by the authors; licensee MDPI.

Salam Z.,University of Technology Malaysia | Amjad M.,University of Technology Malaysia | Amjad M.,Islamia University of Bahawalpur | Facta M.,University of Technology Malaysia | Mekhilef S.,University of Malaya
IEEE Transactions on Power Electronics | Year: 2013

This paper describes the analysis and design of an LCL resonant power supply for ozone generation. The main advantage of the proposed topology is the absence of high-voltage transformer; the high voltage gain is achievable by means of double-resonance phenomena. Furthermore, the bandwidth is wider than the ordinary LC and its phase difference is constant over specific frequency range; as a result, an open-loop operation can be implemented. The complete analysis and design procedure of the power supply is presented. The design procedure is verified by implementing the power supply to drive a dielectric barrier discharge prototype ozone chamber. The hardware results are found to be in close agreement with simulation and thus justify the validity of the design procedures. The proposed circuit is suitable for portable ozone power supply fed by low-voltage source such as battery or photovoltaic module. © 1986-2012 IEEE.

Halawa E.,Charles Darwin University | GhaffarianHoseini A.,University of Malaya | Hin Wa Li D.,City University of Hong Kong
Renewable Energy | Year: 2014

In regions where solar energy is abundant, solar energy can play a vital role in attaining energy sustainability. Sizing solar energy systems requires the availability of solar radiation data on horizontal surface which can then be used to calculate solar radiation intensity on any tilted surface using appropriate conversion factors or formula. In many parts of the world, especially in developing countries, such data is not readily available. Many researchers have found that monthly average daily value of global solar radiation on horizontal surface can be estimated when meteorological parameters such as duration of sunshine, number of rainy days, relative humidity, etc. are available. Many empirical correlations have been developed based on this approach. The development of such a correlation has been made possible through the availability of solar and other meteorological data required for their validation. This paper presents a review on the existing empirical correlations and critically looks at the practicality of such correlations. This raises the question on the appropriateness of the past and present approaches adopted by researchers in this field. The paper also discusses various related aspects and proposes new directions for future research. © 2014 Elsevier Ltd.

Yacob N.A.,University Technology of MARA | Ishak A.,National University of Malaysia | Ishak A.,University of Malaya | Pop I.,Technical University of Cluj Napoca
International Journal of Thermal Sciences | Year: 2011

The steady two-dimensional boundary layer flow past a static or a moving wedge immersed in nanofluids is investigated numerically. An implicit finite difference scheme known as the Keller-box method and the NAG routine DO2HAF are used to obtain the numerical solutions. Three different types of nanoparticles, namely copper Cu, alumina Al2O3 and titania TiO 2 with water as the base fluid are considered. The effects of the governing parameters on the fluid flow and heat transfer characteristics are analyzed and discussed. It is found that Cu-water has the highest skin friction coefficient and the heat transfer rate at the surface compared with the others. The effect of the solid volume fraction of nanoparticles on the fluid flow and heat transfer characteristics is found to be more pronounced compared to the type of the nanoparticles. © 2010 Elsevier Masson SAS. All rights reserved.

Wong Y.M.,Laboratory of Advanced Catalysis and Environmental Technology | Wu T.Y.,University of Selangor | Juan J.C.,Laboratory of Advanced Catalysis and Environmental Technology | Juan J.C.,University of Malaya
Renewable and Sustainable Energy Reviews | Year: 2014

In recent years, the production of hydrogen (H2) via dark fermentation has become increasingly popular because it is a sustainable approach to produce clean energy. This review presents an overview with a critical analysis of the technical challenges in obtaining high H2 yield through dark fermentation. Particular focus is given to the pretreatment methods that affect H2 production. We observed that heat pretreatment is the most frequently applied and the most effective method of eliminating H2-consuming bacteria (HCB) while preserving H2-producing bacteria (HPB). The pre-dominant HPB species after pretreatment belongs to the genus Clostridium and hence the fermentation conditions are optimized according to their preference for H2 production. Besides, we also reviewed fermentation conditions such as substrate, pH, temperature, oxidation-reduction potential (ORP), types of nutrient and inhibitor substrate, to obtain clearer insight on the influences of critical parameters in H2 production. © 2014 Elsevier Ltd.

Al-Matary A.,King Fahad Medical City Riyadh | Ali J.,University of Malaya
BMC Medical Ethics | Year: 2014

Background: Approximately one-fourth of all the inhabitants on earth are Muslims. Due to unprecedented migration, physicians are often confronted with cultures other than their own that adhere to different pdigms. Discussion. In Islam, and most religions, abortion is forbidden. Islam is considerably liberal concerning abortion, which is dependent on (i) the threat of harm to mothers, (ii) the status of the pregnancy before or after ensoulment (on the 120§ssup§th§esup§ day of gestation), and (iii) the presence of foetal anomalies that are incompatible with life. Considerable variation in religious edicts exists, but most Islamic scholars agree that the termination of a pregnancy for foetal anomalies is allowed before ensoulment, after which abortion becomes totally forbidden, even in the presence of foetal abnormalities; the exception being a risk to the mother's life or confirmed intrauterine death. Summary. The authors urge Muslim law makers to also consider abortion post ensoulment if it is certain that the malformed foetus will decease soon after birth or will be severely malformed and physically and mentally incapacitated after birth to avoid substantial hardship that may continue for years for mothers and family members. The authors recommend that an institutional committee governed and monitored by a national committee make decisions pertaining to abortion to ensure that ethics are preserved and mistakes are prevented. Anomalous foetuses must be detected at the earliest possible time to enable an appropriate medical intervention prior to the 120th day. © 2014 Al-Matary and Ali; licensee BioMed Central Ltd.

Laurance W.F.,James Cook University | Clements G.R.,James Cook University | Clements G.R.,University of Malaya | Sloan S.,James Cook University | And 9 more authors.
Nature | Year: 2014

The number and extent of roads will expand dramatically this century. Globally, at least 25 million kilometres of new roads are anticipated by 2050; a 60% increase in the total length of roads over that in 2010. Nine-tenths of all road construction is expected to occur in developing nations, including many regions that sustain exceptional biodiversity and vital ecosystem services. Roads penetrating into wilderness or frontier areas are a major proximate driver of habitat loss and fragmentation, wildfires, overhunting and other environmental degradation, often with irreversible impacts on ecosystems. Unfortunately, much road proliferation is chaotic or poorly planned, and the rate of expansion is so great that it often overwhelms the capacity of environmental planners and managers. Here we present a global scheme for prioritizing road building. This large-scale zoning plan seeks to limit the environmental costs of road expansion while maximizing its benefits for human development, by helping to increase agricultural production, which is an urgent priority given that global food demand could double by mid-century. Our analysis identifies areas with high environmental values where future road building should be avoided if possible, areas where strategic road improvements could promote agricultural development with relatively modest environmental costs, and 'conflict areas' where road building could have sizeable benefits for agriculture but with serious environmental damage. Our plan provides a template for proactively zoning and prioritizing roads during the most explosive era of road expansion in human history. ©2014 Macmillan Publishers Limited. All rights reserved.

Mohammadi K.,University of Massachusetts Amherst | Shamshirband S.,University of Malaya | Petkovic D.,University of Niš | Khorasanizadeh H.,University of Kashan
Renewable and Sustainable Energy Reviews | Year: 2016

Identifying the most relevant variables for diffuse solar radiation prediction is of indispensable importance. In this study, the adaptive neuro-fuzzy inference system (ANFIS) is applied to select the most influential parameters for prediction of daily horizontal diffuse solar radiation (Hd). Ten important variables are nominated to analyze their effects on prediction of Hd in the city of Kerman, situated in the south central part of Iran. To achieve this, a thorough variable selection is conducted for three cases with 1, 2 and 3 inputs to introduce the best and worst inputs combinations. For the cases with 2 and 3 inputs, 45 and 120 possible combinations of inputs are considered, respectively. Providing comparisons between the most and least relevant sets of inputs reveals that appropriate selection of input parameters is an important task in prediction of Hd. For the cases with one input, it is found that sunshine duration (n) is the most influential variable. Moreover, combination of horizontal global solar radiation (H) and extraterrestrial solar radiation (Ho) as well as combination of H, Ho and n are the best sets among the cases with 2 and 3 inputs, respectively. The achieved results specify that combinations of either 2 or 3 most relevant inputs would be appropriate to provide a balance between the simplicity and high precision. Predictions using the most influential sets of 2 and 3 inputs indicate that for the ANFIS model with two inputs, the mean absolute percentage error, mean absolute bias error, root mean square error and correlation coefficient are 23.0579%, 1.0176 MJ/m2, 1.3052 MJ/m2 and 0.8247, respectively, and for the ANFIS model with three inputs they are 18.3143%, 0.8134 MJ/m2, 1.1036 MJ/m2 and 0.8783, respectively. © 2015 Elsevier Ltd. All rights reserved.

Altice F.L.,Yale University | Altice F.L.,University of Malaya | Kamarulzaman A.,University of Malaya | Soriano V.V.,Hospital Carlos III | And 2 more authors.
The Lancet | Year: 2010

HIV-infected drug users have increased age-matched morbidity and mortality compared with HIV-infected people who do not use drugs. Substance-use disorders negatively affect the health of HIV-infected drug users, who also have frequent medical and psychiatric comorbidities that complicate HIV treatment and prevention. Evidence-based treatments are available for the management of substance-use disorders, mental illness, HIV and other infectious complications such as viral hepatitis and tuberculosis, and many non-HIV-associated comorbidities. Tuberculosis co-infection in HIV-infected drug users, including disease caused by drug-resistant strains, is acquired and transmitted as a consequence of inadequate prescription of antiretroviral therapy, poor adherence, and repeated interfaces with congregate settings such as prisons. Medication-assisted therapies provide the strongest evidence for HIV treatment and prevention efforts, yet are often not available where they are needed most. Antiretroviral therapy, when prescribed and adherence is at an optimum, improves health-related outcomes for HIV infection and many of its comorbidities, including tuberculosis, viral hepatitis, and renal and cardiovascular disease. Simultaneous clinical management of multiple comorbidities in HIV-infected drug users might result in complex pharmacokinetic drug interactions that must be adequately addressed. Moreover, interventions to improve adherence to treatment, including integration of health services delivery, are needed. Multifaceted, interdisciplinary approaches are urgently needed to achieve parity in health outcomes in HIV-infected drug users. © 2010 Elsevier Ltd.

Ramasamy R.,University of Malaya | Tuan Ya T.M.Y.S.,Petronas University of Technology
Applied Ocean Research | Year: 2014

The venture of oil and gas exploration into deeper waters has increased drastically in these recent years, as the shallow water fields approaching exhaustion. Large diameter pipelines installed in these areas are exposed to the severe pressure loading resulting from the water depth and any pre-installation damages sustained during transportation or pipelay and may reduce the collapse and buckle propagation resistance drastically. This work focuses on the utilisation and application of the finite element method as a robust and practical engineering tool to establish a methodology for analysing the effects of initial imperfections in the form of dents of various shapes and sizes on pipelines, sustained prior to pipelay, to determine the collapse pressure and buckle propagation pressure which can result in costly abandonments and unnecessary replacements. Comparison between the available theoretical closed-form simplified solutions available via 2D ring analogy, the experimental test conducted by various researchers on steel tubes, empirical formulations from past works and the analysis results obtained from this research were conducted, by incorporating the material plasticity, residual stresses and external pressure. The methodology employed herein provides a relatively realistic and practical assessment tool for computing the collapse and buckle propagation pressures of dented large-diameter submarine pipelines. © 2014 Elsevier Ltd.

Agency: Cordis | Branch: FP7 | Program: CP-FP | Phase: HEALTH.2010.2.3.3-3 | Award Amount: 5.06M | Year: 2010

Since 2005 Chikungunya fever has affected millions of people producing a high fever and a debilitating arthralgia which can persist for months and progress to chronic arthritis. Chikungunya virus has been associated with periodic outbreaks of human disease and is spread by mosquitoes. The current epidemic rose to prominence in 2005/6 following infection of >250,000 people on La Runion. The virus rapidly spread to other islands in the Indian Ocean, India and SE Asia. Chikungunya cases in returning travellers have been reported. In summer 2007 a traveller from India to Italy initiated a locally transmitted outbreak which included one death from encephalitis. The mosquitoes transmitting this infection are spreading and increasing in Europe and could spread as far north as the British Isles. There are diagnostics tests, these require standardisation. The pathogenic mechanisms leading to myalgia, arthralgia, rare encephalitis and chronic arthritis are unknown precluding rational therapeutic intervention. There are no antivirals. There is no licensed vaccine. This project will integrate the expertise of EU laboratories with a long and strong track record of research on alphaviruses with EU laboratories that started work on CHIKV following the outbreak in La Runion and laboratories from SE Asia working on this virus. The project will generate new molecular and cellular tools for research and applied studies, including high-throughput screening and vaccines; standardise, quality assure and distribute key diagnostic tests and develop new ones; determine virus genetic changes across time, geographical regions and species; discover interactions between virus and human cells to inform rational design of therapeutics; study immune responses in the chronic disease in humans, including whether virus persists in joints, the cell types involved and the relationship to immune responses; characterise rodent and non-human primate models of acute and chronic infection to further study the pathogenesis and provide models for antiviral and vaccine screens; screen libraries of characterized pharmaceutical and bioactive compounds for antiviral activity and develop a vaccine which at the end of this project is ready to enter clinical trials.

News Article | November 15, 2016
Site: www.businesswire.com

TAINAN, Taiwan--(BUSINESS WIRE)--In response to Taiwan government’s New Southbound Policy, National Cheng Kung University (NCKU) is committed to serving as the major international education hub in Asia, initiating a joint master degree program to facilitate international student mobility. University of Malaya (UM), Indian Institute of Technology Bombay (IIT Bombay), Institut Teknologi Bandung (ITB), Universiti Malaysia Sabah (UMS), and NCKU signed a Memorandum of Understanding (MoU) November 11

Yousefi R.,Islamic Azad University | Zak A.K.,University of Malaya
Materials Science in Semiconductor Processing | Year: 2011

In this paper the effects of silicon substrates with different orientations on the morphological and optical properties as well as biaxial stress of ZnO nanowires were investigated. The ZnO nanowires were grown on Si(1 0 0) and Si(1 1 1) substrates by the vaporsolid (VS) method using a physical vapor deposition reactor. In addition ZnO nanowires were grown on Si(1 1 1) substrate by the vaporliquidsolid (VLS) method using an Au film as catalyst, which were deposited on Si(1 1 1) substrate using a sputtering method, with the same conditions. Room temperature photoluminescence (PL) spectrum showed a stronger ultraviolet (UV) peak at 381 nm for the nanowires that were grown on Si(1 1 1) by the VS method than those that were grown on Si(1 0 0) with the same green emission (deep-level emission (DLE)) intensities at about 520 nm peak. On the other hand, the PL result of the ZnO nanowires, which were grown by the VLS method, showed the same intensities for the both UV and DLE peaks. Furthermore, the effects of silicon substrate orientation and Au catalyst on biaxial stress of the nanowires were studied by Raman spectrometer. It was discussed that Au catalyst was one of the important factors that could affect the biaxial stress value of the ZnO nanowires that were grown on Si substrates. © 2011 Elsevier Ltd. All rights reserved.

Yousefi R.,Islamic Azad University | Muhamad M.R.,University of Malaya | Zak A.K.,University of Malaya
Current Applied Physics | Year: 2011

In this paper the effect of source temperature on the morphological and optical properties of ZnO nanowires using a thermal evaporation set-up was investigated. A simple horizontal double-tube system was used to grow the ZnO nanowires. The nanowires with different morphology were obtained by the same substrate temperature and different source temperatures. Vertical and aligned nanowires with hexagonal shape were grown at the source temperature of 950 °C, while the nanowires with spear shape were grown at the source temperature of 1050 °C. The diameters of nanowires were the same for the both set of nanowires, approximately. In addition, characterizations showed that the growth direction of the both set of nanowires was [0001]. Room temperature photoluminescence and Raman spectroscopy studies demonstrated that the ZnO nanowires were grown in lower source temperature zone had better crystalline quality and optical properties than those were grown by higher source temperature. © 2010 Elsevier B.V. All rights reserved.

Tay S.L.,University of Malaya | Haseeb A.S.M.A.,University of Malaya | Johan M.R.,University of Malaya | Munroe P.R.,University of New South Wales | Quadir M.Z.,University of New South Wales
Intermetallics | Year: 2013

This paper reports on the effects of adding Ni nanoparticles to a Sn-3.8Ag-0.7Cu solder. The nanocomposite was prepared by manual blending of SAC solder paste with various percentages of Ni particles. Results showed that the addition of Ni nanoparticles did not bring any significant change in the onset melting temperature of the solder. An increase in the weight percentage of nanoparticles in the solder caused an increase of the wetting angle and a decrease of spreading rate. Moreover, the addition of Ni nanoparticles changed the interfacial intermetallic compound morphology from a scalloped structure into a planar type structure, enhanced the growth of (Cu,Ni)6Sn 5 and suppressed that of Cu3Sn. The concentration of Ni in (Cu,Ni)6Sn5 was higher at the solder side compared with the substrate side. No nickel was detected in the Cu3Sn phase. Ni nanoparticle additions caused an increase in the interdiffusion coefficient in (Cu,Ni)6Sn5, but a reduction in Cu3Sn. All these effects found in the Ni nanoparticle doped solder are similar to the case when Ni is added as an alloying element. Hence, it is suggested that Ni nanoparticles dissolve into the molten solder and influence the intermetallic compound formation through conventional alloying effects. © 2012 Elsevier Ltd. All rights reserved.

Mariod A.A.,Sudan University of Science and Technology | Abdelwahab S.I.,University of Malaya
Food Reviews International | Year: 2012

Sclerocarya birrea (Anacardiaceae) is a popular African wild tree distributed in many African countries where the leaves, stem bark, root, and fruits are used in food and traditional medicine; the fruit is rich in ascorbic acid. The fruit juice contains sesquiterpene hydrocarbon, which are terpenes found in plants that are reported to have bacteriostatic properties. The fruit contains a hard brown seed. The seed encloses a soft white kernel rich in oil and protein. The oil contains oleic, palmitic, myristic, and stearic acids; the kernel protein contains amino acids, with a predominance of glutamic acid and arginine. The extracts from different parts showed high total phenolic compounds and radical-scavenging capacities and antioxidant activities. Sclerocarya birrea is widely studied with regard to its antidiabetic, anti-inflammatory, analgesic, antiparasitic, antimicrobial, and antihypertenisve activities. © 2012 Copyright Taylor and Francis Group, LLC.

Tang Y.-Q.,University of Malaya | Jaganath I.B.,Malaysia Agricultural Research and Development Institute MARDI | Sekaran S.D.,University of Malaya
PLoS ONE | Year: 2010

Background: Phyllanthus is a traditional medicinal plant that has been used in the treatment of many diseases including hepatitis and diabetes. The main aim of the present work was to investigate the potential cytotoxic effects of aqueous and methanolic extracts of four Phyllanthus species (P.amarus, P.niruri, P.urinaria and P.watsonii) against skin melanoma and prostate cancer cells. Methodology/Principal Findings: Phyllanthus plant appears to possess cytotoxic properties with half-maximal inhibitory concentration (IC50) values of 150-300 μg/ml for aqueous extract and 50-150 mg/ml for methanolic extract that were determined using the MTS reduction assay. In comparison, the plant extracts did not show any significant cytotoxicity on normal human skin (CCD-1127Sk) and prostate (RWPE-1) cells. The extracts appeared to act by causing the formation of a clear "ladder" fragmentation of apoptotic DNA on agarose gel, displayed TUNEL-positive cells with an elevation of caspase-3 and -7 activities. The Lactate Dehydrogenase (LDH) level was lower than 15% in Phyllanthus treated-cancer cells. These indicate that Phyllanthus extracts have the ability to induce apoptosis with minimal necrotic effects. Furthermore, cell cycle analysis revealed that Phyllanthus induced a Go/G1-phase arrest on PC-3 cells and a S-phase arrest on MeWo cells and these were accompanied by accumulation of cells in the Sub-G1 (apoptosis) phase. The cytotoxic properties may be due to the presence of polyphenol compounds such as ellagitannins, gallotannins, flavonoids and phenolic acids found both in the water and methanol extract of the plants. Conclusions/Significance: Phyllanthus plant exerts its growth inhibition effect in a selective manner towards cancer cells through the modulation of cell cycle and induction of apoptosis via caspases activation in melanoma and prostate cancer cells. Hence, Phyllanthus may be sourced for the development of a potent apoptosis-inducing anticancer agent. © 2010 Tang et al.

Castano-Rodriguez N.,University of New South Wales | Kaakoush N.O.,University of New South Wales | Lee W.S.,University of Malaya | Mitchell H.M.,University of New South Wales
Gut | Year: 2015

Objective To conduct a comprehensive global systematic review and meta-analysis on the association between Helicobacter pylori infection and IBD. As bacterial antigen cross-reactivity has been postulated to be involved in this association, published data on enterohepatic Helicobacter spp (EHS) and Campylobacter spp and IBD was also analysed. Design Electronic databases were searched up to July 2015 for all case-control studies on H. pylori infection/EHS/Campylobacter spp and IBD. Pooled ORs (P-OR) and 95% CIs were obtained using the random effects model. Heterogeneity, sensitivity and stratified analyses were performed. Results Analyses comprising patients with Crohn's disease (CD), UC and IBD unclassified (IBDU), showed a consistent negative association between gastric H. pylori infection and IBD (P-OR: 0.43, p value <1e-10). This association appears to be stronger in patients with CD (P-OR: 0.38, p value <1e-10) and IBDU (P-OR: 0.43, p value=0.008) than UC (P-OR: 0.53, p value <1e-10). Stratification by age, ethnicity and medications showed significant results. In contrast to gastric H. pylori, non H. pylori-EHS (P-OR: 2.62, p value=0.001) and Campylobacter spp, in particular C. concisus (P-OR: 3.76, p value=0.006) and C. showae (P-OR: 2.39, p value=0.027), increase IBD risk. Conclusions H. pylori infection is negatively associated with IBD regardless of ethnicity, age, H. pylori detection methods and previous use of aminosalicylates and corticosteroids. Antibiotics influenced the magnitude of this association. Closely related bacteria including EHS and Campylobacter spp increase the risk of IBD. These results infer that H. pylori might exert an immunomodulatory effect in IBD. © 2015 BMJ Publishing Group Ltd & British Society of Gastroenterology.

Tamjidyamcholo A.,University of Malaya | Bin Baba M.S.,University of Malaya | Tamjid H.,University Putra Malaysia | Gholipour R.,University of Tehran
Computers and Education | Year: 2013

Knowledge sharing is an important component of knowledge management systems. Security knowledge sharing substantially reduces risk and investment in information security. Despite the importance of information security, little research based on knowledge sharing has focused on the security profession. Therefore, this study analyses key factors, containing attitude, self-efficacy, trust, norm of reciprocity, and shared language, in respect of the information security workers intention to share knowledge. Information security professionals in virtual communities, including the Information Security Professional Association (ISPA), Information Systems Security Association (ISSA), Society of Information Risk Analysts (SIRA), and LinkedIn security groups, were surveyed to test the proposed research model. Confirmatory factor analysis (CFA) and the structural equation modelling (SEM) technique were used to analyse the data and evaluate the research model. The results showed that the research model fit the data well and the structural model suggests a strong relationship between attitude, trust, and norms of reciprocity to knowledge sharing intention. Hypotheses regarding the influence of self-efficacy and reciprocity, to knowledge sharing attitude were upheld. Shared language did not influence either the attitude or intention to share knowledge. © 2013 Elsevier Ltd. All rights reserved.

Irfan M.F.,University of Malaya | Usman M.R.,University of Punjab | Kusakabe K.,Fukuoka Women's University
Energy | Year: 2011

Numerous coal gasification studies have been found in the literature those employed various kinds of gasifying agents such as steam and carbon dioxide. These studies are featured with wide variations in the parametric conditions and the usage of equipments. Steam is frequently employed as a gasifying agent, however, in several studies carbon dioxide has also been used as a gasifying agent either pure or in combination with other gasifying agents (H2O, O2, CO, H2). This paper is a brief review of the coal gasification with CO2 as a diluent. Different factors were studied over the coal gasification with CO2 such as coal rank, pressure, temperature, gas composition, catalyst and the minerals present inside the coal, heating rate, particle size, and diverse reactor types. It also deals with the application of the gas-solid models developed in the literature and the combustion and gasification mechanisms for O2/CO2 streams. Moreover, it reviews the kinetics and the reaction rate equations (Arrhenius and Langmuir-Hinshelwood types) for coal-char gasification both in the reaction kinetic control region (low temperature) and the diffusion control region (high temperature) and at both low and high pressures. © 2010 Elsevier Ltd.

Kamkaew A.,Texas A&M University | Lim S.H.,Cancer Research Initiatives Foundation CARIF | Lim S.H.,University of Malaya | Lee H.B.,Cancer Research Initiatives Foundation CARIF | And 3 more authors.
Chemical Society Reviews | Year: 2013

BODIPY dyes tend to be highly fluorescent, but their emissions can be attenuated by adding substituents with appropriate oxidation potentials. Substituents like these have electrons to feed into photoexcited BODIPYs, quenching their fluorescence, thereby generating relatively long-lived triplet states. Singlet oxygen is formed when these triplet states interact with 3O2. In tissues, this causes cell damage in regions that are illuminated, and this is the basis of photodynamic therapy (PDT). The PDT agents that are currently approved for clinical use do not feature BODIPYs, but there are many reasons to believe that this situation will change. This review summarizes the attributes of BODIPY dyes for PDT, and in some related areas.

Madlool N.A.,University of Kufa | Madlool N.A.,University of Malaya | Saidur R.,University of Malaya | Rahim N.A.,University of Malaya | Kamalisarvestani M.,University of Malaya
Renewable and Sustainable Energy Reviews | Year: 2013

Due the advances in the industrial processes, in which the cement industry is a major contributor, energy consumption and greenhouse gas emission has increased significantly. This paper reviews previous studies on energy saving, carbon dioxide emission reductions and the various technologies used to improve the energy efficiency in the cement industry. Energy efficiency measures for raw materials preparation, clinker production, products and feedstock changes, general energy efficiency measures, and finish grinding have been surveyed. It was found that the largest recorded amounts of thermal energy savings, electrical energy savings and emission reductions to date are 3.4 GJ/t, 35 kW h/t and 212.54 kgCO2/t, respectively. © 2012 Elsevier Ltd.

Ismail M.S.,University of Malaya | Moghavvemi M.,University of Malaya | Moghavvemi M.,University of Tehran | Mahlia T.M.I.,University of Tenaga Nasional
Renewable and Sustainable Energy Reviews | Year: 2013

Microturbines are a relatively new distributed generation technology. Combined heat and power, known as cogeneration, can be considered the most economical attractive investment in microturbines. Latest technologies and increasing energy prices are propelling this technology to the forefront. This study aims to review the current state of utilization of microturbines in distributed generation as a standalone system or within a hybrid system to supply loads. It is found that more research and development effort is needed to improve the performance of microturbines, integrate them with other energy sources and adopt standards and regulations to connect them with the utility grid. These standards shall be developed to serve all parties and take into account regional and international requirements. Furthermore, complete mathematical modeling, especially for fuel consumption is still required. The development of small scale units within the range of kilowatts for in-house use as a backup source of residential PV system is also needed. © 2012 Elsevier Ltd.

Hassanpour M.,Islamic Azad University | Shafigh P.,University of Malaya | Mahmud H.B.,University of Malaya
Construction and Building Materials | Year: 2012

The higher brittleness and lower mechanical properties of lightweight aggregate concrete (LWAC) compared to normal weight concrete (NWC) at the same compressive strength has prevented it from being widely used in the construction industry despite its many advantages. Studies have shown that the use of fibers in LWAC is an appropriate solution to resolve such problems. This paper reviews the influence of the addition of fibers on the properties of different types of LWAC. These properties include the workability, compressive strength, stress-strain behavior, tensile strength, modulus of elasticity, and compressive and flexural toughness. Generally, the inclusion of fibers in LWAC, as single or hybrid forms, improve its mechanical properties, and significantly increase its toughness, ductility performance and energy absorption, while decreasing its workability, particularly when steel fiber is used in the concrete mixture. In the case of splitting tensile and flexural strengths, the effectiveness of fiber in LWAC is more pronounced than NWC. © 2012 Elsevier Ltd. All rights reserved.

Idris M.A.,University of Malaya | Dollard M.F.,University of South Australia | Yulita,University of Malaya
Journal of Occupational Health Psychology | Year: 2014

This multilevel longitudinal study investigates a newly identified climate construct, psychosocial safety climate (PSC), as a precursor to job characteristics (e.g., emotional demands), and psychological outcomes (i.e., emotional exhaustion and depression). We argued that PSC, as an organizational climate construct, has cross-level effects on individually perceived job design and psychological outcomes. We hypothesized a mediation process between PSC and emotional exhaustion particularly through emotional demands. In sequence, we predicted that emotional exhaustion would predict depression. At Time 1, data were collected from employees in 36 Malaysian private sector organizations (80% responses rate), n = 253 (56%), and at Time 2 from 27 organizations (60%) and n = 117 (46%). Using hierarchical linear modeling (HLM), we found that there were cross-level effects of PSC Time 1 on emotional demands Time 2 and emotional exhaustion Time 2, but not on depression Time 2, across a 3-month time lag. We found evidence for a lagged mediated effect; emotional demands mediated the relationship between PSC and emotional exhaustion. Emotional exhaustion did not predict depression. Finally, our results suggest that PSC is an important organizational climate construct, and acts to reduce employee psychological problems in the workplace, via working conditions. © 2014 American Psychological Association.

Ellis L.,University of Malaya | Hoskin A.W.,Idaho State University
Aggression and Violent Behavior | Year: 2015

Evolutionary neuroandrogenic (ENA) theory contends that males are more involved in crime than females due to an evolved female preference for mates who are (or at least appear to be) stable resource provisioners. To accommodate this female preference, the theory states that males have evolved genetic tendencies to produce a high level of testosterone and other androgens that enhance their competitiveness, often to the point of victimizing others. Adolescent expressions of competitive/victimizing behavior are often crude, thus frequently manifesting themselves in the form of behavior that others seek to suppress. By full adulthood, most individuals with highly androgenized brains will have transitioned from crude forms to refined forms of competitive/victimizing behavior, typically as part of their normal occupational and financial activities. The theory asserts that learning ability as well as opportunities to learn forms of competition that minimally victimize others, determine how fast individuals transition from crude to refined forms of competitiveness. In the present article, ENA theory is elaborated upon and used to explain three phenomena not previously addressed by the theory: (a) the rise of the criminal justice system, (b) the criminalization of victimless offenses, and (c) gang activities and terrorism. According to the theory, all of these phenomena have similar evolutionary and neurohormonal underpinnings. © 2015.

Shields M.D.,Queen's University of Belfast | Thavagnanam S.,University of Malaya
Cough | Year: 2013

Cough is one of the most common symptoms that patients bring to the attention of primary care clinicians. Cough can be designated as acute (<3 weeks in duration), prolonged acute cough (3 to 8 weeks in duration) or chronic (> 8 weeks in duration). The use of the term 'prolonged acute cough' in a cough guideline allows a period of natural resolution to occur before further investigations are warranted. The common causes are in children with post viral or pertussis like illnesses causing the cough. Persistent bacterial bronchitis typically occurs when an initial dry acute cough due to a viral infection becomes a prolonged wet cough remaining long after the febrile illness has resolved. This cough responds to a completed course of appropriate antibiotics. © 2013 Shields and Thavagnanam; licensee BioMed Central Ltd.

Lee S.H.,University of Malaya | Jaganath I.B.,Malaysia Agricultural Research and Development Institute MARDI | Wang S.M.,University of Malaya | Sekaran S.D.,University of Malaya
PLoS ONE | Year: 2011

Background: Current chemotherapeutic drugs kill cancer cells mainly by inducing apoptosis. However, they become ineffective once cancer cell has the ability to metastasize, hence the poor prognosis and high mortality rate. Therefore, the purpose of this study was to evaluate the antimetastatic potential of Phyllanthus (P. niruri, P. urinaria, P. watsonii, and P. amarus) on lung and breast carcinoma cells. Methodology/Principal Findings: Cytotoxicity of Phyllanthus plant extracts were first screened using the MTS reduction assay. They were shown to inhibit MCF-7 (breast carcinoma) and A549 (lung carcinoma) cells growth with IC50 values ranging from 50-180 μg/ml and 65-470 μg/ml for methanolic and aqueous extracts respectively. In comparison, they have lower toxicity on normal cells with the cell viability percentage remaining above 50% when treated up to 1000 μg/ml for both extracts. After determining the non-toxic effective dose, several antimetastasis assays were carried out and Phyllanthus extracts were shown to effectively reduce invasion, migration, and adhesion of both MCF-7 and A549 cells in a dose-dependent manner, at concentrations ranging from 20-200 μg/ml for methanolic extracts and 50-500 μg/ml for aqueous extracts. This was followed by an evaluation of the possible modes of cell death that occurred along with the antimetastatic activity. Phyllanthus was shown to be capable of inducing apoptosis in conjunction with its antimetastastic action, with more than three fold increase of caspases-3 and -7, the presence of DNA-fragmentation and TUNEL-positive cells. The ability of Phyllanthus to exert antimetastatic activities is mostly associated to the presence of polyphenol compounds in its extracts. Conclusions/Significance: The presence of polyphenol compounds in the Phyllanthus plant is critically important in the inhibition of the invasion, migration, and adhesion of cancer cells, along with the involvement of apoptosis induction. Hence, Phyllanthus could be a valuable candidate in the treatment of metastatic cancers. © 2011 Lee et al.

Ismail M.S.,University of Malaya | Moghavvemi M.,University of Malaya | Moghavvemi M.,University of Tehran | Mahlia T.M.I.,University of Tenaga Nasional
Energy Conversion and Management | Year: 2013

A techno-economic analysis and the design of a complete hybrid system, consisting of photovoltaic (PV) panels, a battery system and a diesel generator as a backup power source for a typical Malaysian village household is presented in this paper. The specifications of the different components constructing the hybrid system were also determined. A scenario depending on a standalone PV and other scenario depending on a diesel generator only were also analyzed. A simulation program was developed to simulate the operation of these different scenarios. The scenario that achieves the minimum cost while meeting the load requirement was selected. The optimal tilt angle of the PV panels in order to increase the generated energy was obtained using genetic algorithm. In addition, sensitivity analysis was undertaken to evaluate the effect of change of some parameters on the cost of energy. The results indicated that the optimal scenario is the one that consists of a combination of the PV panels, battery bank and a diesel generator. Powering a rural house using this hybrid system is advantageous as it decreases operating cost, increases efficiencies, and reduces pollutant emissions. © 2013 Elsevier B.V. All rights reserved.

News Article | November 14, 2016
Site: www.sciencedaily.com

Nanoscale manipulation on the surface of materials could stimulate cells to differentiate into specific tissues -- eliminating the use of growth or transcription factors. Researchers are trying to find ways to control cellular response in vitro using engineered materials in a continuous pursuit to regenerate injured or diseased tissues. Recent studies have found that nanoscale structure of the materials, on which such cells are cultured, affect how well they proliferate and develop into the tissues they are meant to become. Scientists from the University of Malaya in Malaysia, Dr. Belinda Pingguan-Murphy et al., together with Prof. Sheikh Ali Akbar of Ohio State University, reviewed the most recent research on how the nanoscale topographies affect cellular regenerative responses. For example, human fetal osteoblast cells that are involved in bone formation were found to grow better on materials that had tiny protrusions on their surfaces (11 nanometers in height) compared to surfaces that were either flat or had higher protrusions. They also attached better to surfaces with nanosized pits that were 14 nm or 29 nm deep compared to flat surfaces and surfaces with pits that were 45 nm deep. Research has also found that the distance between pits or protrusions and whether they are random or highly ordered also affect how osteoblasts and stem cells respond. Additionally, nanoscale grooved surfaces trigger these cells to grow in the direction of the grooves. Generally, when a material is exposed to a biological fluid, water molecules bind rapidly to the surface followed by the incorporation of chloride and sodium ions. Proteins then adsorb to this surface. The resulting mixture of proteins, as well as their three-dimensional shape and orientation with respect to the surface topography, sends signals to the cells influencing their attachment and spreading. Further research in this area may lead to the development of clinical prostheses with topographies that can directly modulate stem cell fate, enabling cell growth and development to be tailored to a specific application without using potentially harmful chemicals, write the researchers in their review published in the journal of Science and Technology of Advanced Materials. However, developing low-cost, high-output fabrication techniques that allow for the development of specific nano-topographies is still a limiting factor.

News Article | November 7, 2016
Site: phys.org

Researchers are trying to find ways to control cellular response in vitro using engineered materials in a continuous pursuit to regenerate injured or diseased tissues. Recent studies have found that nanoscale structure of the materials, on which such cells are cultured, affect how well they proliferate and develop into the tissues they are meant to become. Scientists from the University of Malaya in Malaysia, Dr. Belinda Pingguan-Murphy et al., together with Prof. Sheikh Ali Akbar of Ohio State University, reviewed the most recent research on how the nanoscale topographies affect cellular regenerative responses. For example, human fetal osteoblast cells that are involved in bone formation were found to grow better on materials that had tiny protrusions on their surfaces (11 nanometers in height) compared to surfaces that were either flat or had higher protrusions. They also attached better to surfaces with nanosized pits that were 14 nm or 29 nm deep compared to flat surfaces and surfaces with pits that were 45 nm deep. Research has also found that the distance between pits or protrusions and whether they are random or highly ordered also affect how osteoblasts and stem cells respond. Additionally, nanoscale grooved surfaces trigger these cells to grow in the direction of the grooves. Generally, when a material is exposed to a biological fluid, water molecules bind rapidly to the surface followed by the incorporation of chloride and sodium ions. Proteins then adsorb to this surface. The resulting mixture of proteins, as well as their three-dimensional shape and orientation with respect to the surface topography, sends signals to the cells influencing their attachment and spreading. Further research in this area may lead to the development of clinical prostheses with topographies that can directly modulate stem cell fate, enabling cell growth and development to be tailored to a specific application without using potentially harmful chemicals, write the researchers in their review published in the journal of Science and Technology of Advanced Materials. However, developing low-cost, high-output fabrication techniques that allow for the development of specific nano-topographies is still a limiting factor. Explore further: Stem cells shape up to their surroundings More information: Nur Izzati Aminuddin et al. Osteoblast and stem cell response to nanoscale topographies: a review, Science and Technology of Advanced Materials (2016). DOI: 10.1080/14686996.2016.1242999

News Article | November 8, 2016
Site: www.sciencedaily.com

New research in Science and Technology of Advanced Materials discovers that nanoscale manipulation on the surface of materials could stimulate cells to differentiate into specific tissues -- eliminating the use of growth or transcription factors. Researchers are trying to find ways to control cellular response in vitro using engineered materials in a continuous pursuit to regenerate injured or diseased tissues. Recent studies have found that nanoscale structure of the materials, on which such cells are cultured, affect how well they proliferate and develop into the tissues they are meant to become. Scientists from the University of Malaya in Malaysia, Dr. Belinda Pingguan-Murphy et al., together with Prof. Sheikh Ali Akbar of Ohio State University, reviewed the most recent research on how the nanoscale topographies affect cellular regenerative responses. For example, human fetal osteoblast cells that are involved in bone formation were found to grow better on materials that had tiny protrusions on their surfaces (11 nanometers in height) compared to surfaces that were either flat or had higher protrusions. They also attached better to surfaces with nanosized pits that were 14 nm or 29 nm deep compared to flat surfaces and surfaces with pits that were 45 nm deep. Research has also found that the distance between pits or protrusions and whether they are random or highly ordered also affect how osteoblasts and stem cells respond. Additionally, nanoscale grooved surfaces trigger these cells to grow in the direction of the grooves. Generally, when a material is exposed to a biological fluid, water molecules bind rapidly to the surface followed by the incorporation of chloride and sodium ions. Proteins then adsorb to this surface. The resulting mixture of proteins, as well as their three-dimensional shape and orientation with respect to the surface topography, sends signals to the cells influencing their attachment and spreading. Further research in this area may lead to the development of clinical prostheses with topographies that can directly modulate stem cell fate, enabling cell growth and development to be tailored to a specific application without using potentially harmful chemicals, write the researchers in their review published in the journal of Science and Technology of Advanced Materials. However, developing low-cost, high-output fabrication techniques that allow for the development of specific nano-topographies is still a limiting factor.

News Article | November 9, 2016
Site: www.newsmaker.com.au

Tsukuba, Japan, Nov 9, 2016 - (ACN Newswire) - Researchers are trying to find ways to control cellular response in vitro using engineered materials in a continuous pursuit to regenerate injured or diseased tissues. Recent studies have found that nanoscale structure of the materials, on which such cells are cultured, affect how well they proliferate and develop into the tissues they are meant to become. Scientists from the University of Malaya in Malaysia, Dr. Belinda Pingguan-Murphy et al., together with Prof. Sheikh Ali Akbar of Ohio State University, reviewed the most recent research on how the nanoscale topographies affect cellular regenerative responses. For example, human fetal osteoblast cells that are involved in bone formation were found to grow better on materials that had tiny protrusions on their surfaces (11 nanometers in height) compared to surfaces that were either flat or had higher protrusions. They also attached better to surfaces with nanosized pits that were 14 nm or 29 nm deep compared to flat surfaces and surfaces with pits that were 45 nm deep. Research has also found that the distance between pits or protrusions and whether they are random or highly ordered also affect how osteoblasts and stem cells respond. Additionally, nanoscale grooved surfaces trigger these cells to grow in the direction of the grooves. Generally, when a material is exposed to a biological fluid, water molecules bind rapidly to the surface followed by the incorporation of chloride and sodium ions. Proteins then adsorb to this surface. The resulting mixture of proteins, as well as their three-dimensional shape and orientation with respect to the surface topography, sends signals to the cells influencing their attachment and spreading. Further research in this area may lead to the development of clinical prostheses with topographies that can directly modulate stem cell fate, enabling cell growth and development to be tailored to a specific application without using potentially harmful chemicals, write the researchers in their review published in the journal of Science and Technology of Advanced Materials. However, developing low-cost, high-output fabrication techniques that allow for the development of specific nano-topographies is still a limiting factor. For further information please contact:  Associate Professor Dr. Belinda Pingguan-Murphy*,  University Malaya - Biomedical Engineering Kuala Lumpur, Wilayah Persekutuan, Malaysia (*); e-mail: [email protected] Ms. Nur Izzati Aminuddin,  University of Malaya - Biomedical Engineering Kuala Lumpur, Wilayah Persekutuan, Malaysia Dr. Roslina Ahmad, University of Malaya - Mechanical Engineering Kuala Lumpur, Wilayah Persekutuan, Malaysia Professor Sheikh Ali Akbar, Ohio State University Columbus, Ohio, United States Article information  Pingguan-Murphy, Belinda (*); Aminuddin, Nur Izzati; Ahmad, Roslina; Akbar, Sheikh Ali:  "Osteoblast and stem cell response to nanoscale topographies: a review",  Science and Technology of Advanced Materials Vol. 17 (2016) p.1242999. http://dx.doi.org/10.1080/14686996.2016.1242999 Journal information Science and Technology of Advanced Materials (STAM, http://www.tandfonline.com/toc/tsta20/current) is an international open access journal in materials science. The journal covers a broad spectrum of topics, including synthesis, processing, theoretical analysis and experimental characterization of materials. Emphasis is placed on the interdisciplinary nature of materials science and on issues at the forefront of the field, such as energy and environmental issues, as well as medical and bioengineering applications. For more information about STAM contact Mikiko Tanifuji Publishing Director Science and Technology of Advanced Materials E-mail: [email protected] Press release distributed by ResearchSEA for Science and Technology of Advanced Materials.

News Article | November 9, 2016
Site: www.acnnewswire.com

The Highs and Lows of Regenerative Medicine Nanoscale manipulation on the surface of materials could stimulate cells to differentiate into specific tissues - eliminating the use of growth or transcription factors. Researchers are trying to find ways to control cellular response in vitro using engineered materials in a continuous pursuit to regenerate injured or diseased tissues. Recent studies have found that nanoscale structure of the materials, on which such cells are cultured, affect how well they proliferate and develop into the tissues they are meant to become. Scientists from the University of Malaya in Malaysia, Dr. Belinda Pingguan-Murphy et al., together with Prof. Sheikh Ali Akbar of Ohio State University, reviewed the most recent research on how the nanoscale topographies affect cellular regenerative responses. For example, human fetal osteoblast cells that are involved in bone formation were found to grow better on materials that had tiny protrusions on their surfaces (11 nanometers in height) compared to surfaces that were either flat or had higher protrusions. They also attached better to surfaces with nanosized pits that were 14 nm or 29 nm deep compared to flat surfaces and surfaces with pits that were 45 nm deep. Research has also found that the distance between pits or protrusions and whether they are random or highly ordered also affect how osteoblasts and stem cells respond. Additionally, nanoscale grooved surfaces trigger these cells to grow in the direction of the grooves. Generally, when a material is exposed to a biological fluid, water molecules bind rapidly to the surface followed by the incorporation of chloride and sodium ions. Proteins then adsorb to this surface. The resulting mixture of proteins, as well as their three-dimensional shape and orientation with respect to the surface topography, sends signals to the cells influencing their attachment and spreading. Further research in this area may lead to the development of clinical prostheses with topographies that can directly modulate stem cell fate, enabling cell growth and development to be tailored to a specific application without using potentially harmful chemicals, write the researchers in their review published in the journal of Science and Technology of Advanced Materials. However, developing low-cost, high-output fabrication techniques that allow for the development of specific nano-topographies is still a limiting factor. For further information please contact: Associate Professor Dr. Belinda Pingguan-Murphy*, University Malaya - Biomedical Engineering Kuala Lumpur, Wilayah Persekutuan, Malaysia (*); e-mail: Ms. Nur Izzati Aminuddin, University of Malaya - Biomedical Engineering Kuala Lumpur, Wilayah Persekutuan, Malaysia Dr. Roslina Ahmad, University of Malaya - Mechanical Engineering Kuala Lumpur, Wilayah Persekutuan, Malaysia Professor Sheikh Ali Akbar, Ohio State University Columbus, Ohio, United States Article information Pingguan-Murphy, Belinda (*); Aminuddin, Nur Izzati; Ahmad, Roslina; Akbar, Sheikh Ali: "Osteoblast and stem cell response to nanoscale topographies: a review", Science and Technology of Advanced Materials Vol. 17 (2016) p.1242999. http://dx.doi.org/10.1080/14686996.2016.1242999 Journal information Science and Technology of Advanced Materials (STAM, http://www.tandfonline.com/toc/tsta20/current) is an international open access journal in materials science. The journal covers a broad spectrum of topics, including synthesis, processing, theoretical analysis and experimental characterization of materials. Emphasis is placed on the interdisciplinary nature of materials science and on issues at the forefront of the field, such as energy and environmental issues, as well as medical and bioengineering applications. For more information about STAM contact Mikiko Tanifuji Publishing Director Science and Technology of Advanced Materials E-mail: Press release distributed by ResearchSEA for Science and Technology of Advanced Materials.

Shahbaz M.,COMSATS Institute of Information Technology | Tiwari A.K.,ICFAI University, Tripura | Jam F.A.,University of Malaya | Ozturk I.,Cag University
Renewable and Sustainable Energy Reviews | Year: 2014

This paper investigates the unit root properties of coal consumption per capita for the 47 developed and developing countries for 1965-2010 period. To examine the stationary properties of coal consumption per capita, Lagrange multiplier (LM) unit root test with one break and two breaks Crash model has been utilized. According to empirical results, the coal consumption is stationary in almost all the countries analyzed. Thus, if the coal consumption is mean (or trend) reverting, then it follows that the series will return to its mean value (or trend path) and it might be possible to forecast future movements in the coal consumption based on past behaviors of the series. For the policy makers, it is not necessary to pay attention to coal consumption excepting for Indian and Italian. However, for the researchers it is important to take into account the stationarity property of coal consumption and also structural breaks (should be modeled) in their future studies. © 2014 Elsevier Ltd.

Tan H.M.,Sime Darby Medical Center | Tan H.M.,University of Malaya | Tong S.F.,National University of Malaysia | Ho C.C.,National University of Malaysia
Journal of Sexual Medicine | Year: 2012

Introduction. Sexual dysfunction in men, such as erectile dysfunction, hypogonadism, and premature ejaculation, generates considerable attention. Its association with physical and psychological health is an issue which should be addressed seriously. Aim. A review of the literature pertaining to the correlation between sexual dysfunction and physical and psychological health. Methods. PubMed search for relevant publications on the association between sexual dysfunction in men and physical and psychological health. Main Outcome Measure. Clinical and epidemiological evidence that demonstrates the association between sexual dysfunction in men and physical and psychological health. Results. Sexual dysfunction, i.e., erectile dysfunction, hypogonadism, and premature ejaculation, has been shown to be associated with physical and psychological health. There is a strong correlation between sexual dysfunction and cardiovascular disease, metabolic syndrome, quality of life, and depression. Conclusion. The association between men's sexual dysfunction and physical and psychological health is real and proven. Therefore, it should not be taken lightly but instead treated as a life-threatening medical problem. © 2011 International Society for Sexual Medicine.

Narmashiri K.,Islamic Azad University at Zahedan | Ramli Sulong N.H.,University of Malaya | Jumaat M.Z.,University of Malaya
Construction and Building Materials | Year: 2012

This paper reports the experimental and numerical investigations on the Carbon Fibre Reinforced Polymer (CFRP) failure analysis and structural behaviour of the CFRP flexural strengthened steel I-beams. Understanding the CFRP failure modes is useful to find solutions for preventing or retarding the failures. One non-strengthened control beam and twelve strengthened beams using different types and dimensions of CFRP strips in both experimental test and simulation modelling studies were investigated. In the experimental test, four-point bending method with static gradual loading was applied. To simulate the specimens, the ANSYS software in full three dimensional (3D) modelling case and non-linear analysis method was utilized. The results show the CFRP failure modes used in flexural strengthening of steel I-beams include below point load splitting (BS), below point load debonding (BD), end delamination (EDL), and end debonding (ED). The occurrences and sequences of CFRP failure modes depended on the strengthening schedule. The structural performance of the CFRP strengthened steel beams also varied according to the strengthening specifications investigated in this research. © 2011 Elsevier Ltd. All rights reserved.

Moghadasi S.I.,University of Malaya | Ravana S.D.,University of Malaya | Raman S.N.,National University of Malaysia
Journal of Informetrics | Year: 2013

For a system-based information retrieval evaluation, test collection model still remains as a costly task. Producing relevance judgments is an expensive, time consuming task which has to be performed by human assessors. It is not viable to assess the relevancy of every single document in a corpus against each topic for a large collection. In an experimental-based environment, partial judgment on the basis of a pooling method is created to substitute a complete assessment of documents for relevancy. Due to the increasing number of documents, topics, and retrieval systems, the need to perform low-cost evaluations while obtaining reliable results is essential. Researchers are seeking techniques to reduce the costs of experimental IR evaluation process by the means of reducing the number of relevance judgments to be performed or even eliminating them while still obtaining reliable results. In this paper, various state-of-the-art approaches in performing low-cost retrieval evaluation are discussed under each of the following categories; selecting the best sets of documents to be judged; calculating evaluation measures, both, robust to incomplete judgments; statistical inference of evaluation metrics; inference of judgments on relevance, query selection; techniques to test the reliability of the evaluation and reusability of the constructed collections; and other alternative methods to pooling. This paper is intended to link the reader to the corpus of 'must read' papers in the area of low-cost evaluation of IR systems. © 2012 Elsevier Ltd.

Yau Y.H.,University of Malaya | Hasbi S.,National University of Malaysia
Renewable and Sustainable Energy Reviews | Year: 2013

Climate observations in recent years indicate that the effects of climate change events are apparently having an increasing impact on society. These impacts will likely also affect the building sector. Numerous studies have been conducted to assess future building energy consumption rates. However, these studies often do not take into account climatic variability and consumer reactions towards a temperature shift. A literature review on climate change impacts for commercial buildings and their technical services in the tropics was carried out. This review focuses on the buildings' contributions towards climate change as well as climate change impacts on building structures, changing patterns of energy use and peak demands, building heating and cooling requirements, thermal comfort and emissions impacts. In general, buildings in regions with a predicted increase in temperature will need more cooling and less heating loads. Thus, building energy consumption and carbon emissions are projected to rise during its operational phase. In addition, the erratic weather trends will also affect the building efficiency and sustainability, indoor air quality and thermal comfort. Even though the existing literature on this issue has increased substantially in recent years, there is still a need for further research in tropical climates as the climate change impacts vary with the different seasons, periods and regions. © 2012 Elsevier Ltd. All rights reserved.

Daud A.-K.,Bank of The West | Ismail M.S.,University of Malaya
Renewable Energy | Year: 2012

Hybrid power systems based on renewable energy sources, especially photovoltaic and wind energy are an effective option to solve the power-supply problem for remote and isolated areas far from the grids. This paper presents a study and design of a complete hybrid system for providing the electrical loads in a family house in Palestine according to their energy requirements.A computer program is developed to achieve this and to determine the specifications of the whole system components. It uses the data of wind and solar radiation measurements of the selected rural zone and all the required information about the electrical loads. Also, the hybrid systems minimizing, simultaneously, the total cost throughout the useful life of the installation, pollutant emissions (CO 2) and dump load are taken into consideration.It is found that providing electricity to a family house in a rural zone using hybrid systems is very beneficial and competitive with the other types of conventional energy sources, especially considering the decreasing prices of these systems and their increasing efficiencies and reliability. They have also the advantage of maintaining a clean environment. © 2012 Elsevier Ltd.

Zainal H.,National University of Malaysia | Zainab A.N.,University of Malaya
Health Information and Libraries Journal | Year: 2011

Background: The aim of this study was to examine Malaysian contributions in the field of biomedical and health sciences. Methods: In this study, 3697 publications affiliated to Malaysian addresses from the sci database between 1990 and 2005 were sampled. This study also explored publication productivity trends, authorship and collaboration pattern, core journals used, and citations obtained. Results: Main contributions were journal articles (73.3%). Most authors (63.7%) contributed only one article and 16.1% produced over 30-68 publications. Multi-authored works were the norm. The productive authors were named either first or second in publications. There were active collaborations with authors from Asia-Pacific countries (35%) and Europe (30%). The majority of publications were contributed by institutions of higher learning (87%). Core journals used follow quite close to Bradford's zonal ratios of 44:152:581. The active research areas were identified. About 71.3% of publications received citations especially those published from 1995 to 1999. Conclusion: This study helped librarians identify active researchers, active research areas and journals relevant to biomedical and health sciences researchers and useful when producing reports to university management and planning medical collection policies and deciding on journal subscriptions and cancellations. © 2011 The authors. Health Information and Libraries Journal © 2011 Health Libraries Group.

Bhandari A.K.,Indian Institute of Information Technology, Design and Manufacturing | Singh V.K.,Indian Institute of Information Technology, Design and Manufacturing | Kumar A.,Indian Institute of Information Technology, Design and Manufacturing | Singh G.K.,Indian Institute of Technology Roorkee | Singh G.K.,University of Malaya
Expert Systems with Applications | Year: 2014

The objective of image segmentation is to extract meaningful objects. A meaningful segmentation selects the proper threshold values to optimize a criterion using entropy. The conventional multilevel thresholding methods are efficient for bi-level thresholding. However, they are computationally expensive when extended to multilevel thresholding since they exhaustively search the optimal thresholds to optimize the objective functions. To overcome this problem, two successful swarm-intelligence-based global optimization algorithms, cuckoo search (CS) algorithm and wind driven optimization (WDO) for multilevel thresholding using Kapur's entropy has been employed. For this purpose, best solution as fitness function is achieved through CS and WDO algorithm using Kapur's entropy for optimal multilevel thresholding. A new approach of CS and WDO algorithm is used for selection of optimal threshold value. This algorithm is used to obtain the best solution or best fitness value from the initial random threshold values, and to evaluate the quality of a solution, correlation function is used. Experimental results have been examined on standard set of satellite images using various numbers of thresholds. The results based on Kapur's entropy reveal that CS, ELR-CS and WDO method can be accurately and efficiently used in multilevel thresholding problem. © 2013 Elsevier B.V. All rights reserved.

Siar C.H.,University of Malaya | Lau S.H.,Institute for Medical Research | Han K.,Institute for Medical Research
Journal of Oral and Maxillofacial Surgery | Year: 2012

Purpose: Ameloblastoma of the human jaw is an uncommon but clinically significant odontogenic epithelial neoplasm. The aim was to analyze the clinicopathologic characteristics of ameloblastoma in a Malaysian population. Materials and Methods: This is a retrospective study (1993 through 2008) of consecutive ameloblastoma cases accessioned in 2 main oral pathology diagnostic centers: the Unit of Stomatology, Institute for Medical Research and the Department of Oral Pathology, Oral Medicine, and Periodontology, Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia. Data on patient demographics, tumor location, symptomology, duration, radiographic appearance, preoperative diagnosis, clinicopathologic subtypes, treatment, and recurrence were analyzed. Results: Three hundred forty cases of ameloblastoma were reviewed. These were from 197 male patients (57.9%) and 143 female patients (42.1%), with a male-to-female ratio of 1.4:1. A wide age range (7 to 85 years), mean onset age of 30.3 × 16.3 years, and peak incidence in the second decade of life were recorded. Most were mandibular tumors (n = 311/340, 91.5%). These consisted of 95 (28%) unicystic ameloblastomas, 221 (65%) solid/multicystic ameloblastomas, 22 (6.4%) desmoplastic ameloblastoma, and 2 (0.6%) peripheral ameloblastomas. Unicystic ameloblastoma (41.1%) and solid/multicystic ameloblastoma (52.0%) mostly affected Malays patients, whereas desmoplastic ameloblastoma (59.1%) was prevalent in Chinese patients. Unicystic ameloblastoma (56.8%) and solid/multicystic ameloblastoma (47.1%) occurred predominantly in the body and posterior mandible, whereas desmoplastic ameloblastoma (36.4%) preferentially involved the anterior jaw segment. Most tumors presented as multilocular radiolucencies (36.8%). Enucleation (n = 42/92, 45.7%) was the treatment of choice. About 18 cases (13.3%) presented with recurrence. Conclusions: Because ameloblastoma subsets differ in their biologic behavior, the present data are significant as baseline references for clinicians and pathologists. © 2012 American Association of Oral and Maxillofacial Surgeons.

Tan L.H.,Sunway Medical Center | Lum L.C.S.,University of Malaya | Omar S.F.S.,University of Malaya | Kan F.K.,Hospital Sultanah Aminah
Journal of Clinical Virology | Year: 2012

Hemophagocytic syndrome is a potentially fatal disorder. It is being increasingly reported but remained under-recognized in dengue. Most reported cases were in association with plasma leakage and shock but multi-organ impairment was also observed. We describe the time-lines of 6 cases of confirmed dengue with varying severities of hemophagocytosis. All had persistent fever, cytopenia and elevated transaminases with markedly elevated ferritin levels during and beyond the plasma leakage phase. Acute renal failure and central nervous system manifestation were observed in two patients. Morphological hemophagocytosis was demonstrated in three patients. All survivors showed clinical and biochemical resolution of hemophagocytosis indicating its transient nature. Persistence of fever and cytopenia together with multi-organ dysfunction, out of proportion to and beyond the plasma leakage phase should prompt clinicians to consider this phenomenon. © 2012 Elsevier B.V.

Tiwari A.K.,ICFAI University, Tripura | Shahbaz M.,COMSATS Institute of Information Technology | Adnan Hye Q.M.,University of Malaya
Renewable and Sustainable Energy Reviews | Year: 2013

This study investigates the dynamic relationship between coal consumption, economic growth, trade openness and CO2 emissions in case of India. In doing so, Narayan and Popp, Journal of Applied Statistics 2010; 37:1425-1438, structural break unit test is applied to test the order of integration of the variables. Long run relationship between the variables is tested by applying the ARDL bounds testing approach to cointegration developed by Pesaran et al. Journal of Applied Econometrics 2001; 16:289-326. The results confirm the existence of cointegration for long run between coal consumption, economic growth, trade openness and CO2 emissions. Our empirical exercise indicates the presence of environmental Kuznets curve (EKC) in long run as well as in short run. Coal consumption as well as trade openness contributes to CO2 emissions. The causality analysis reports the feedback hypothesis between economic growth and CO2 emissions and same inference is drawn between coal consumption and CO2 emissions. Moreover, trade openness Granger causes economic growth, coal consumption and CO2 emissions. © 2012 Elsevier Ltd. All rights reserved.

Shahbaz M.,COMSATS Institute of Information Technology | Hye Q.M.A.,University of Malaya | Tiwari A.K.,ICFAI University, Tripura | Leitao N.C.,Polytechnic Institute of Santarém
Renewable and Sustainable Energy Reviews | Year: 2013

This study examines the linkages among economic growth, energy consumption, financial development, trade openness and CO2 emissions over the period of 1975Q1-2011Q4 in case of Indonesia. The stationary analysis is performed by using Zivot-Andrews unit root test and the ARDL bounds testing approach for a long run relationship between the series in the presence of structural breaks. The causality between the concerned variables is examined by the VECM Granger causality technique and robustness of causal analysis is tested by innovative accounting approach (IAA). Our results confirm that the variables are cointegrated; it means that the long run relationship exists in the presence of structural breaks. The empirical findings indicate that economic growth and energy consumption increase CO2 emissions, while financial development and trade openness compact it. The VECM causality analysis has shown the feedback hypothesis between energy consumption and CO2 emissions. Economic growth and CO2 emissions are also interrelated i.e. bidirectional causality. Financial development Granger causes CO2 emissions. The study opens up new policy insights to control the environment from degradation by using energy efficient technologies. Financial development and trade openness can also play their role in improving the environmental quality. © 2013 Elsevier Ltd.

Saidur R.,University of Malaya | Leong K.Y.,National University of Malaysia | Mohammad H.A.,University of Tenaga Nasional
Renewable and Sustainable Energy Reviews | Year: 2011

Nanofluids are potential heat transfer fluids with enhanced thermophysical properties and heat transfer performance can be applied in many devices for better performances (i.e. energy, heat transfer and other performances). In this paper, a comprehensive literature on the applications and challenges of nanofluids have been compiled and reviewed. Latest up to date literatures on the applications and challenges in terms of PhD and Master thesis, journal articles, conference proceedings, reports and web materials have been reviewed and reported. Recent researches have indicated that substitution of conventional coolants by nanofluids appears promising. Specific application of nanofluids in engine cooling, solar water heating, cooling of electronics, cooling of transformer oil, improving diesel generator efficiency, cooling of heat exchanging devices, improving heat transfer efficiency of chillers, domestic refrigerator-freezers, cooling in machining, in nuclear reactor and defense and space have been reviewed and presented. Authors also critically analyzed some of the applications and identified research gaps for further research. Moreover, challenges and future directions of applications of nanofluids have been reviewed and presented in this paper. Based on results available in the literatures, it has been found nanofluids have a much higher and strongly temperature-dependent thermal conductivity at very low particle concentrations than conventional fluids. This can be considered as one of the key parameters for enhanced performances for many of the applications of nanofluids. Because of its superior thermal performances, latest up to date literatures on this property have been summarized and presented in this paper as well. However, few barriers and challenges that have been identified in this review must be addressed carefully before it can be fully implemented in the industrial applications. © 2010 Elsevier Ltd.

Huat Siar C.,University of Malaya | Ng K.H.,Institute for Medical Research
Journal of Oral Pathology and Medicine | Year: 2014

Background: Epithelial-to-mesenchymal transition (EMT) via the mechanism of transcription repression is a crucial process for the induction of invasiveness in many human tumors. Ameloblastoma is a benign odontogenic epithelial neoplasm with a locally infiltrative behavior. Twist, an EMT promoter, has been implicated in its invasiveness. The roles of the other transcription factors remain unclarified. Materials and methods: Four transcription factors, namely Snail, Slug, SIP1, and Twist, were examined immunohistochemically in 64 ameloblastoma [18 unicystic (UA), 20 solid/multicystic (SA), 4 desmoplastic (DA), and 22 recurrent (RA)]. Results: All four transcription factors were differentially expressed in ameloblastoma [Snail: n = 60/64 (94%); Slug: n = 21/64 (33%); SIP: n = 18/64 (28%); Twist: n = 26/64 (41%)] (P < 0.05). Their distribution patterns were heterogeneous and were not significantly different between the tumor invasive front and central area (P > 0.05). Intracellular protein localization was predominantly nuclear for Snail, cytoplasmic>nuclear for Slug and SIP1, and cytoplasmic/nuclear for Twist. Overexpression of Snail in most subsets (UA = 18/18; SMA = 19/20; DA = 4/4; RA = 19/22) compared with the other transcription factors (P < 0.05) and selective expression for Slug, SIP1, and Twist in squamous/keratinous foci and at sites of epithelial cystic degeneration were among the main observations made. Stromal cells surrounding immunoreactive tumor cells tended to stain positive. Conclusions: Present findings suggest that these transcription factors probably play differential roles in mediating local invasiveness in ameloblastoma. Overexpression of Snail in most subsets suggests that this molecule is most likely the prototype transcription factor involved in inducing EMT in the ameloblastoma. © 2013 John Wiley & Sons A/S.

News Article | February 19, 2017
Site: news.yahoo.com

A medical staff member pushes a trolley in front the main gate to the forensic department at Kuala Lumpur Hospital in Kuala Lumpur, Malaysia Saturday, Feb. 18, 2017. Malaysia performed a second autopsy on the estranged half brother of North Korea’s leader because the first procedure was inconclusive, piling on the intrigue surrounding what appeared to be a well-executed assassination at an airport in Kuala Lumpur, an official said Saturday. Police also arrested a fourth suspect, identified as a North Korean man. (AP Photo/Daniel Chan) KUALA LUMPUR, Malaysia (AP) — At a hospital morgue in Malaysia's capital, the tightly guarded corpse of a middle-aged man has become the focus of a dizzying case of international intrigue involving five countries, combative North Korean diplomats and an apparently duped female assassin. Investigators are still trying to piece together details of what appears to be the brazen assassination of Kim Jong Nam, the half brother of North Korea's mercurial ruler and an exiled member of the country's elite. Malaysian police said Saturday that they had arrested a fourth suspect, a 46-year-old North Korean man. Kim, who had been estranged from his younger half sibling for years, was attacked at Kuala Lumpur International Airport on Monday. A rotund man in his mid-40s, he told medical workers at the airport that he had been sprayed in the face with a chemical. He grew dizzy, suffered a seizure and was dead within hours, Malaysian officials said. Without citing much in the way of evidence, observers including South Korea pointed to the obvious culprit in Monday's attack: Kim's half brother, Kim Jong Un, who has executed or purged a slew of high-level officials since taking power in 2011. As the rumor mill swirled, Malaysia arrested four people over the course of the week — including an Indonesian woman who told investigators she was duped into thinking she was part of a comedy show prank. North Korean officials made no public comments for several days, but they privately demanded custody of Kim's body and strongly objected to an autopsy. The Malaysians went ahead with the autopsy anyway, saying they were simply following procedure. On Friday night, North Korea's ambassador to Malaysia broke his silence. At an unusual news conference held close to midnight outside the morgue, Ambassador Kang Chol said Malaysia may be "trying to conceal something" and "colluding with hostile forces." "We will categorically reject the result of the post-mortem," Kang said, adding that the procedure was carried out "unilaterally and excluding our attendance." Malaysia is one of just a handful of countries to have full diplomatic ties with North Korea, with each country having an embassy in the other's capital. Malaysia has also been a key place for quiet, semi-official "track 2" diplomatic talks between North Korea and the United States. The results of the autopsy have not been released publicly, but a Malaysian official with knowledge of the investigation said the results were inconclusive and that there was a second autopsy Friday night. He asked that his name not be used because he was not authorized to speak to the media. Malaysian police official Abdul Samah Mat, however, denied that the second autopsy had taken place. Less than a week after Kim's death, the case had already reached well beyond Malaysia to North Korea, South Korea and Indonesia, along with Macau, where Kim lived with his family, and Vietnam, which was looking into whether another of the suspects was a citizen. The intrigue over the case raises all sorts of questions about Kim's mysterious death, but a lack of closure and a lingering sense of the unknown are not unusual when it comes to North Korea. While South Korea has blamed North Korea for a slew of notable assassinations or attempted killings in past decades, the North often denies involvement or simply doesn't comment. The suspects in Malaysian custody are: Siti Aisyah, the Indonesian woman; another woman, who carried Vietnamese travel documents and was seen on closed circuit television footage in a shirt with "LOL" emblazoned across the front; a man investigators said is Aisyah's boyfriend; and the North Korean man, who was arrested Friday night. Malaysia is seeking DNA samples from Kim Jong Nam's immediate family. He is believed to have two sons and a daughter with two women living in Beijing and Macau. Kim reportedly fell out of favor in Pyongyang in 2001, when he was caught trying to enter Japan on a false passport to visit Tokyo Disneyland. He and his younger brother have the same father, the late Kim Jong Il. Even as diplomatic ties between Malaysia and North Korea frayed, Malaysian officials appeared to be carefully following internal protocols for issues like control of the body, analysts said. It's likely that Malaysia is hoping that following strict procedures would keep them from antagonizing North Korea — or anyone else in the international community. "As a very small country, Malaysia does not take sides," said Geetha Govindasamy, a senior lecturer in East Asia studies at the University of Malaya who has studied North Korean ties to Southeast Asia. Associated Press writer Tim Sullivan in New Delhi contributed to this report.

Lock J.H.-J.,Royal Perth Hospital | Fong K.C.S.,University of Malaya
Clinical and Experimental Optometry | Year: 2011

Since its discovery in the 1940s, retinal photocoagulation has evolved immensely. Although the first photocoagulators used incandescent light, it was the invention of the laser that instigated the widespread use of photocoagulation for treatment of retinal diseases. Laser permits selection of electromagnetic wavelength, energy levels, spot size and pulse duration. These variables are crucial for accurate targeting of retinal tissue and prevention of detrimental side-effects such as central blind spots. There is ongoing clinical research dedicated to optimising such parameters and many innovative modes of laser delivery are now being offered. Laser photocoagulation is the mainstay of treatment for various retinal and macular diseases. Considering the escalating prevalence of such conditions and widespread use of photocoagulation, it is important for optometrists to grasp the basic principles and be aware of new developments in retinal laser therapy. © 2010 The Authors. Clinical and Experimental Optometry © 2010 Optometrists Association Australia.

Jones E.B.G.,University of Malaya | Pang K.-L.,National Taiwan Ocean University
Biodiversity and Conservation | Year: 2012

This paper reports on the distribution of fungal communities in aquatic habitats in tropical regions and highlights differences in the taxa observed in freshwater and marine habitats. Ascomycetes are dominant on substrata in marine environments, with few basidiomycetes and discomycetes. Equally, few freshwater basidiomycetes and discomycetes have been reported from the tropics. In marine habitats, Dothideomycetes dominate on mangrove substrata, and halosphaeriaceous species are most numerous on submerged woody substrata in coastal waters, while yeasts are common in seawater and estuarine habitats. In freshwater, Ingoldian anamorphic fungi are most numerous on decaying leaves, while ascomycetes (Dothideomycetes, Sordariomycetes) are prevalent on submerged/exposed woody substrata. Unique fungi are found in tropical waters and differ from those in temperate locations. © 2011 Springer Science+Business Media B.V.

Khiar A.S.A.,Universiti Sains Islam Malaysia | Arof A.K.,University of Malaya
Ionics | Year: 2010

A proton-conducting polymer electrolyte based on starch and ammonium nitrate (NH4NO3) has been prepared through solution casting method. Ionic conductivity for the system was conducted over a wide range of frequency between 50 Hz and 1 MHz and at temperatures between 303 K and 373 K. Impedance analysis shows that sample with 25 wt.% NH4NO3 has a smaller bulk resistance (Rb) compared to that of the pure sample. The amount of NH4NO3 was found to influence the proton conduction; the highest obtainable room temperature conductivity was 2.83 × 10-5 S cm-1, while at 100 °C, the conductivity in found to be 2.09 × 10-4 S cm-1. The dielectric analysis demonstrates a non-Debye behavior. Transport parameters of the samples were calculated using the Rice and Roth model and thus shows that the increase in conductivity is due to the increase in the number of mobile ions. © Springer-Verlag 2009.

Kamkaew A.,Texas A&M University | Burgess K.,Texas A&M University | Burgess K.,University of Malaya
Chemical Communications | Year: 2015

Attempts to make a diamino disulfonic acid derivative of an aza-BODIPY showed it was difficult to add BF2 to a disulfonated azadipyrromethene, and sulfonation of an aza-BODIPY resulted in loss of the BF2 fragment. We conclude the electron-deficient character of aza-BODIPY dyes destabilizes them relative to BODIPY dyes. Consequently, sulfonation of the aza-BODIPY core is not a viable strategy to increase water solubility. This assertion was indirectly supported via stability studies of a BODIPY and an aza-BODIPY in aqueous media. To afford the desired compound type, an aza-BODIPY with two amino and two sulfonic acid groups was prepared via modification of the aryl substituents with cysteic acid. This journal is © The Royal Society of Chemistry 2015.

Singh S.,University of Malaya | Yong C.K.,Prince Court Medical Center | Mariapan S.,Teluk Intan Hospital
Journal of Shoulder and Elbow Surgery | Year: 2012

Background: To perform closed manual reduction of acute anterior shoulder dislocation using the traction-countertraction technique requires sedation (TCTS) and the participation of 2 people. We studied the modified Milch (MM) technique, a positional reductive maneuver that requires 1 operator, without patient sedation or analgesia. Materials and methods: The study comprised 56 prospective nonrandomized consecutive patients, of whom 31 were in group A (MM, nonsedated) and 25 in group B (TCTS). Results: The success rate of MM technique was 83.9% (26 of 31), which increased to 96.3% (26 of 27) when 4 patients with associated greater tuberosity fractures were excluded. The success rate was 100% in the TCTS group, with 5 patients with associated greater tuberosity fractures. The reduction in pain from the preprocedural to intraprocedural phases in MM group was significant (P < .001), at a reduction rate of 2.07 (29%) on the numeric rating scale pain score. There was a greater pain reduction rate of 2.43 (34%) on the numeric rating scale when patients with greater tuberosity fractures were excluded. The MM group had a significantly shorter hospital stay (mean, 35 minutes) than the TCTS group (mean, 4 hours). No postreduction neurovascular or fracture complications occurred in either group. Conclusions: The results showed that the Milch technique was effective, safe, shortened hospital stay, and was well tolerated. We recommend the modified Milch technique as a first-line maneuver for acute anterior shoulder dislocations without associated fractures. © 2012.

News Article | April 13, 2016
Site: phys.org

Many research studies have reported the synthesis of alkyds from vegetable oils for surface coatings. In particular, soybean, castor, linseed and tall oils are very suitable because these oils have very high level of unsaturation which enable them to air-dry through oxidation. Palm oil is non-drying oil because of its low iodine value and its alkyds are not capable of forming film by air oxidation. This could be overcome by adopting alternative crosslinking reactions not requiring unsaturation. Water soluble alkyds are made with 28-45% w/w of palm stearin by two stages. The palm stearin was first reacted with glycerol to form monoglycerides, which then polymerize with phthalic anhydride and pentaerythritol to form polyester with excess hydroxyl groups. Trimellitic anhydride was then added to graft the hydrophilic carboxylic acid groups into the polymer structure. The alkyd was neutralized with triethylamine and solubilized in water with butanol and butylcellosolve as cosolvents. The alkyds have been formulated into water-based clear baking enamels by mixing with commercial methylated melamine formaldehyde resin. Color enamel paints were also produced through incorporating pigments and other additives. These enamels can be cured at temperature between 100-140°C and they exhibit good adhesion, film hardness and high gloss, and the resulted palm oil-based polymers have numerous applications. A tire is an assembly of numerous components that are built up on a drum and then vulcanized in a press under heat and pressure. Few layers of the tire components need to be held in place by a tacky compound. In a collaborative research project with Sumitomo Rubber, sticky palm oil-based alkyds were developed as tackifiers in tire compounds. These tacky alkyds have performed better than the conventional tackifier such as polyterpene and petroleum resin. In addition, the tackifier was absorbed into the rubber during vulcanization and has modified the properties of the track and the side-wall rubber, improving the tire performance in terms of better road gripping and lower rolling resistance. Amalgam is one of the oldest dental materials which has been used for filling of tooth cavities. It can release minute amounts of mercury whose toxicity at high intake levels is well-established. People with amalgam filling were found to have higher concentrations of mercury in their blood, urine, kidney and brain. Consequently, mercury amalgam has become less popular due to its poor aesthetic value and worry about mercury poisoning. The use of amalgam has been banned many countries. Composite resins based on Bis-GMA (2,2-bis[4-(2-hydroxy-3-methacryloxyprop-1-oxy)phenyl]propane) and TEGDMA (triethylene glycol dimethacrylate) have been developed. These resins have two acrylate terminals that could be polymerized by free radical initiators activated by light. In collaboration with the staff of the Faculty of Dentistry, University of Malaya, new acrylate terminated oligomer based on a palm oil polyol has been developed as the matrix system for dental restorative composite materials. At the first stage a palm oil-based polyol with three hydroxyl groups was reacted with excess diisocyanate to produce a urethane pre-polymer with three terminal –NCO groups. Next, this pre-polymer is reacted with HEMA (hydroxylethylmethylacrylate) to produce the acrylate terminated BPUTMA (Biopolyol urethane triimethacrylate). Compared to the commercial composite resins, the BPUTMA can be cured with light faster and possesses better mechanical properties. Polyvinyl chloride (PVC) is one of the important technical polymers that has been utilized in many industries. It can be found in wide varieties of products, ranging from structural materials and piping, medical devices, and household appliances. Raw PVC is a rigid plastic, in order to improve the flexibility, plasticisers are added during fabrication of products. These plasticisers are incorporated into PVC through weak physical interaction. Many case studies have shown migration of plasticisers out from PVC intravenous blood bags, PVC container, plastic kitchen wrap, and plastic toys. Consequently, many of these plasticisers (such as DOP) which are harmful to health have been banned from such applications. We have synthesized polyesters from palm oil derivatives to function as plasticisers. Besides being able to soften the hard plastic, they have improved the thermal stability of PVC and shown good migration resistance presumably through chain entanglement. A nanoemulsion has particle size less than 100 nm, and appears "transparent". While is a normal emulsion (particle size >0.1 mm) appears opaque like latex. The low molecular weight alkyds synthesized from palm oil and natural occurring carboxylic acids and glycerol and emulsified in non-toxic surfactant, are of interest for the production of nanoemulsion as delivery systems for nucleic acids, proteins and small molecule drugs. These alkyds nanoemusion exhibit good biocompatiblity with no measurable cytotoxicity at concentrations of 3-100 µg/mL following exposure for 24, 48 and 72 hours. Phenytoin, a drug for wound healing, has been succeefully loaded in the nanoemulsion at 3-200µg/mL. Results show no drug-alkyd interactions over extended time period and absence of drug degradation on storage. The failure of many structural polymers begins from cracks within the materials. Efforts are being made to integrate self-healing ability to the material. One of the ways to achieve this objective is to store "healing agents" in microcapsules that are then embedded into the polymer matrix. The healing process is triggered when the cracks rupture the microcapsules, releasing the healing agent that could flow to fill the gap and solidify through suitable reaction mechanism such as crosslinking with certain reactive groups of the matrix to repair the crack. Our recent works have shown that palm oil alkyds having free carboxylic acid groups can react with epoxidized natural rubber. This observation has led us to the idea of using the alkyd for self-healing application in epoxy matrix. Explore further: How to make palm oil without destroying forests

Law J.W.,University of Selangor | Ab Mutalib N.-S.,UKM Medical Molecular Biology Institute UMBI | Chan K.-G.,University of Malaya | Lee L.-H.,University of Selangor
Frontiers in Microbiology | Year: 2015

The incidence of foodborne diseases has increased over the years and resulted in major public health problem globally. Foodborne pathogens can be found in various foods and it is important to detect foodborne pathogens to provide safe food supply and to prevent foodborne diseases. The conventional methods used to detect foodborne pathogen are time consuming and laborious. Hence, a variety of methods have been developed for rapid detection of foodborne pathogens as it is required in many food analyses. Rapid detection methods can be categorized into nucleic acid-based, biosensor-based and immunological-based methods. This review emphasizes on the principles and application of recent rapid methods for the detection of foodborne bacterial pathogens. Detection methods included are simple polymerase chain reaction (PCR), multiplex PCR, real-time PCR, nucleic acid sequence-based amplification (NASBA), loop-mediated isothermal amplification (LAMP) and oligonucleotide DNA microarray which classified as nucleic acid-based methods; optical, electrochemical and mass-based biosensors which classified as biosensor-based methods; enzyme-linked immunosorbent assay (ELISA) and lateral flow immunoassay which classified as immunological-based methods. In general, rapid detection methods are generally time-efficient, sensitive, specific and labor-saving. The developments of rapid detection methods are vital in prevention and treatment of foodborne diseases. © 2015 Law, Ab Mutalib, Chan and Lee.

Asadieraghi M.,University of Malaya | Asadieraghi M.,Iran National Petrochemical Company | Wan Daud W.M.A.,University of Malaya
Energy Conversion and Management | Year: 2014

To eliminate the negative impacts of inorganic constituents during biomass thermochemical processes, leaching method by different diluted acid solutions was chosen. The different palm oil biomass samples (palm kernel shell (PKS), empty fruit bunches (EFB) and palm mesocarp fiber (PMF)) were pretreated by various diluted acid solutions (H2SO4, HClO4, HF, HNO3, HCl). Acids with the highest degrees of demineralization were selected to investigate the dematerialization impacts on the biomass thermal characteristics and physiochemical structure. Thermogravimetric analysis coupled with mass spectroscopy (TGA-MS) and Fourier transform infrared spectroscopy (TGA-FTIR) were employed to examine the biomass thermal degradation. TGA and DTG (Derivative thermogravimetry) indicated that the maximum degradation temperatures increased after acid pretreatment due to the minerals catalytic effects. The main permanent evolved gases comprising H 2, CO2, CO were detected online during analysis. The major permanent gases produced at the temperature range of 250-750 °C were attributed to the condensable vapors cracking and probably some secondary reactions. The physiochemical structure change of the acid-treated biomass samples was examined by using Brunauer Emmett Teller (BET) method, Scanning Electron Microscope (SEM) and FTIR. The pyrolysis kinetics of the different palm oil biomasses were investigated using first order reaction model. © 2014 Elsevier Ltd. All rights reserved.

Tan A.W.,University of Malaya | Pingguan-Murphy B.,University of Malaya | Ahmad R.,University of Malaya | Akbar S.A.,Ohio State University
Ceramics International | Year: 2012

Titania (TiO 2) nanotube is gaining prominence as an implantation material due to its unique properties such as high specific surface area and the ability to exhibit positive cellular response. In this paper, we briefly review the current state of fabrication methods to synthesize nanotubular TiO 2 surface topography, and discuss its effect on cellular response of different cells in terms of cell adhesion, proliferation and differentiation. In vitro and in vivo studies by using TiO 2 nanotubes are also presented establishing the potential of nanotubes in biomedical applications. Finally, an outlook of future growth of research in TiO 2 nanostructures beyond the nanotubes is provided © 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Panwar N.L.,Maharana Pratap University of Agriculture and Technology | Kothari R.,Babasaheb Bhimrao Ambedkar University | Tyagi V.V.,University of Malaya
Renewable and Sustainable Energy Reviews | Year: 2012

Biomass is indirect source of solar energy and it is renewable in nature. It is one of the most important energy source in near future because of its extensive spread availability and promising potential to reduce global warming. Thermo chemical conversion of biomass yield variety of solid, liquid and gaseous fuels and have equal importance both at industrial and ecological point of views. Present review gives holistic view of various thermo-chemical conversion route of biomass. Gasification technology, pyrolysis options and scope of potential by product from there routes like hydrogen and charcoal production comprehensively reviewed with present context. © 2012 Elsevier Ltd. All rights reserved.

Tyagi V.V.,University of Malaya | Panwar N.L.,Maharana Pratap University of Agriculture and Technology | Rahim N.A.,University of Malaya | Kothari R.,Babasaheb Bhimrao Ambedkar University
Renewable and Sustainable Energy Reviews | Year: 2012

In order to produce process heat for drying of agricultural, textile, marine products, heating of buildings and re-generating dehumidify agent, solar energy is one of the promising heat sources for meeting energy demand without putting adverse impact of environment. Hence it plays a key role for sustainable development. Solar energy is intermittent in nature and time dependent energy source. Owing to this nature, PCMs based thermal energy storage system can achieve the more popularity for solar energy based heating systems. The recent researches focused on the phase change materials (PCMs), as latent heat storage is more efficient than sensible heat storage. In this paper an attempt has been made to present holistic view of available solar air heater for different applications and their performance. © 2011 Elsevier Ltd. All rights reserved.

Motamedi S.,University of Malaya | Song K.-I.,Inha University | Hashim R.,University of Malaya
Materials and Structures/Materiaux et Constructions | Year: 2015

Recently, ground improvement has become much more feasible. Chemical stabilization is a quick and affordable approach to enhancing soil characteristics. An important avenue of research is discovering alternative materials for use in soil enhancement. Pulverized fuel ash (PFA), which is a waste byproduct of coal power plants, has been shown to reduce the environmental risks and costs involved in construction. In this study, a series of unconfined compressive tests were performed for various mixtures of cement, PFA, and sand; the tests considered both the curing period and the optimum moisture content (OMC). In addition, multiple variable linear regression was used to analyze laboratory data in order to obtain an empirical relationship that can be used to predict the unconfined compressive strength (UCS) of a PFA–cement–sand mixture. The accuracy of the model was verified using statistical indices. The first objective of this study was to assess the effects of PFA content on the UCS of the mixture. The second was to investigate the impact of the OMC on the UCS. The focal point of this study was its derivation of a relationship that can be used to estimate the UCS on the basis of existing variables. The results indicated that PFA can strengthen sand in terms of the UCS and that excessive PFA in a mixture may adversely affect the UCS of a medium. Therefore, a mixture must have an optimum proportion of compounds. The OMC plays a vital role in enhancing UCS. The UCS of different mixtures can be predicted with an acceptable level of accuracy by using the relationship derived in this study. © 2014, RILEM.

Zhan S.-Z.,Shantou University | Li M.,Shantou University | Ng S.W.,University of Malaya | Ng S.W.,King Abdulaziz University | Li D.,Shantou University
Chemistry - A European Journal | Year: 2013

Two classical copper(I)-cluster-based luminophores, namely, Cu 4I4 and [Cu3Pz3]2 (Pz=pyrazolate), are immobilized in a supramolecular system through the formation of metal-organic framework (MOF) materials. This series of luminescent MOF materials, namely, [Cu4I4(NH3)Cu 3(L1)3]n, [Cu4I4(NH 2CH3)Cu3(L1)3]n, and [Cu4I4Cu3(L2)3]n (L1=3-(4-pyridyl)-5-(p-tolyl)pyrazolate; L2=3-(4-pyridyl)-5-(2,4-dimethylphenyl) pyrazolate), exhibit diverse thermochromism attributed to the relative functioning efficacy of the two coordination luminophores. Such an intriguing chemopalette effect is regulated by the different supramolecular microenvironments between the two-dimensional layers of these MOFs, and in particular, by the fine-tuned Cu-Cu distances in the excimeric [Cu 3Pz3]2 luminophore. The structure-property elucidation of the thermochromic behavior allows one to understand these optical materials with unusual dual-emissive properties. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ishaque K.,University of Technology Malaysia | Ishaque K.,Karachi Institute of Economics & Technology | Salam Z.,University of Technology Malaysia | Amjad M.,University of Technology Malaysia | Mekhilef S.,University of Malaya
IEEE Transactions on Power Electronics | Year: 2012

This paper proposes an improved maximum power point tracking (MPPT) method for the photovoltaic (PV) system using a modified particle swarm optimization (PSO) algorithm. The main advantage of the method is the reduction of the steady-state oscillation (to practically zero) once the maximum power point (MPP) is located. Furthermore, the proposed method has the ability to track the MPP for the extreme environmental condition, e.g., large fluctuations of insolation and partial shading condition. The algorithm is simple and can be computed very rapidly; thus, its implementation using a low-cost microcontroller is possible. To evaluate the effectiveness of the proposed method, MATLAB simulations are carried out under very challenging conditions, namely step changes in irradiance, step changes in load, and partial shading of the PV array. Its performance is compared with the conventional Hill Climbing (HC) method. Finally, an experimental rig that comprises of a buck-boost converter fed by a custom-designed solar array simulator is set up to emulate the simulation. The software development is carried out in the Dspace 1104 environment using a TMS320F240 digital signal processor. The superiority of the proposed method over the HC in terms of tracking speed and steady-state oscillations is highlighted by simulation and experimental results. © 2012 IEEE.

Ishaque K.,University of Technology Malaysia | Ishaque K.,Karachi Institute of Economics & Technology | Salam Z.,University of Technology Malaysia | Mekhilef S.,University of Malaya | Shamsudin A.,University of Technology Malaysia
Applied Energy | Year: 2012

This paper proposes a penalty based differential evolution (P-DE) for extracting the parameters of solar photovoltaic (PV) modules at different environmental conditions. The two diode model of a solar cell is used as the basis for the extraction problem. The analyses carried out using synthetic current-voltage (I-V) data set showed that the proposed P-DE outperforms other Evolutionary Algorithm methods, namely the simulated annealing (SA), genetic algorithm (GA), and particle swarm optimization (PSO). P-DE consistently converges to the global optimum values very rapidly. The performances are evaluated using the well known quality test and student T-tests. Furthermore, the P-DE extraction method is practically validated by six solar modules of different types (multi-crystalline, mono-crystalline, and thin-film). The results were found to be in close agreement with the experimental I-V data set, especially at very low irradiance values. The latter can be very useful in predicting the performance of the solar system under partial shading conditions. The main application of the proposed work is the possibility of developing a highly accurate simulator for solar PV system designer. © 2012 Elsevier Ltd.

Lee W.S.,University of Malaya | Sokol R.J.,Aurora University
Journal of Pediatrics | Year: 2013

An ever-increasing number of nuclear gene mutations have been identified as responsible for mitochondrial hepatopathies. A diagnosis of such a hepatopathy is suggested by lactic acidosis, hepatic steatosis, liver failure without markedly increased aminotransferase levels, and features of extrahepatic involvement. At present, genotyping is available for many of the mutations identified. Although medical therapy is currently inadequate, selective LT may be life-saving in carefully selected cases, with special caution regarding the presence of extrahepatic disease. Copyright © 2013 Mosby Inc. All rights reserved.

Yaghmaie M.,Tarbiat Modares University | Bahreininejad A.,Tarbiat Modares University | Bahreininejad A.,University of Malaya
Expert Systems with Applications | Year: 2011

Evolution of Web technologies has made e-learning a popular common way of education and training. As an outcome, learning content adaptation has been the subject of many research projects lately. This paper suggests a framework for building an adaptive Learning Management System (LMS). The proposed architecture is based upon multi-agent systems and uses both Sharable Content Object Reference Model (SCORM) 2004 and semantic Web ontology for learning content storage, sequencing and adaptation. This system has been implemented upon a well known open-source LMS and its functionalities are demonstrated through the simulation of a scenario mimicing the real life conditions. The result reveals the system effectiveness for which it appears that the proposed approach may be very promising. © 2010 Elsevier Ltd. All rights reserved.

Tang C.F.,University of Malaya | Shahbaz M.,COMSATS Institute of Information Technology | Arouri M.,EDHEC Business School
Energy Policy | Year: 2013

In the previous decades, a number of studies have been conducted to analyse the causal relationship between electricity consumption and economic growth in the Portuguese economy. However, the evidence remains controversial because the previous studies do not provide clear causality evidence. This might be attributed to the omitted variables bias because most previous studies only focus on the relationship between electricity consumption and economic growth in a bi-variate model. This paper attempts to re-investigate the relationship between electricity consumption and economic growth in Portugal using a multivariate model. Based on the bounds testing approach to cointegration and the Granger causality test within the vector error-correction model (VECM), our empirical results confirm the presence of cointegration among the variables. Moreover, there is evidence of bi-directional causality between electricity consumption and economic growth in the short- and long-run. This suggests that energy is an important source of economic growth in Portugal. Therefore, energy conservation policies should not be implemented because it would deteriorate the process of economic growth and development of the Portuguese economy. © 2013 Elsevier Ltd.

Abid S.A.,University of Malaya | Othman M.,University of Malaya | Shah N.,COMSATS Institute of Information Technology
ACM Computing Surveys | Year: 2014

Mobile ad hoc networks (MANETs) are infrastructureless and distributed communication systems that require sophisticated approaches to routing to cope with node mobility and heterogeneous application requirements. In the past few years, distributed hash table (DHT) has come forth as a useful additional technique to the design and specification of spontaneous and self-organized networks. Researchers have exploited its advantages by implementing it at the network layer and developing scalable routing protocols for MANETs. The implementation of DHT-based routing in a MANET requires different algorithms and specifications compared to routing in the Internet because a MANET has its unique characteristics, such as node mobility, spontaneous networking, decentralized architecture, limited transmission range, dynamic topology, and frequent network partitioning/merging. In this article, we present a comprehensive survey of research related to DHT-based routing that aims at enhancing the scalability of MANETs. We present a vivid taxonomy of DHT-based routing protocols and the guidelines to design such protocols for MANETs. We compare the features, strengths, and weaknesses of existing DHT-based routing protocols and highlight key research challenges that are vital to address. The outcome of the analysis serves as a guide for anyone willing to delve into research on DHT-based routing in MANETs. © 2014 ACM.

Saidur R.,University of Malaya | Kazi S.N.,University of Malaya | Hossain M.S.,University of Malaya | Rahman M.M.,Bangladesh University of Engineering and Technology | Mohammed H.A.,University of Selangor
Renewable and Sustainable Energy Reviews | Year: 2011

Recently scientists used nanoparticles in refrigeration systems because of theirs remarkable improvement in thermo-physical, and heat transfer capabilities to enhance the efficiency and reliability of refrigeration and air conditioning system. In this paper thermal-physical properties of nanoparticles suspended in refrigerant and lubricating oil of refrigerating systems were reviewed. Heat transfer performance of different nanorefrigerants with varying concentrations was reviewed and review results are presented as well. Pressure drop and pumping power of a refrigeration system with nanorefrigerants were obtained from different sources and reported in this review. Along with these, pool boiling heat transfer performance of CNT refrigerant was reported. Moreover, challenges and future direction of nanofluids/nanorefrigerants have been reviewed and presented in this paper. Based on results available in the literatures, it has been found that nanorefrigerants have a much higher and strongly temperature-dependent thermal conductivity at very low particle concentrations than conventional refrigerant. This can be considered as one of the key parameters for enhanced performance for refrigeration and air conditioning systems. Because of its superior thermal performances, latest upto date literatures on this property has been summarized and presented in this paper as well. The results indicate that HFC134a and mineral oil with TiO2 nanoparticles works normally and safely in the refrigerator with better performance. The energy consumption of the HFC134a refrigerant using mineral oil and nanoparticles mixture as lubricant saved 26.1% energy with 0.1% mass fraction TiO2 nanoparticles compared to the HFC134a and POE oil system. It was identified that fundamental properties (i.e. density, specific heat capacity, and surface tension) of nanorefrigerants were not experimentally determined yet. It may be noted as well that few barriers and challenges those have been identified in this review must be addressed carefully before it can be fully implemented in refrigeration and air conditioning systems. © 2010 Elsevier Ltd.

Anantharaj R.,University of Malaya | Banerjee T.,Indian Institute of Technology Guwahati
Journal of Chemical and Engineering Data | Year: 2013

1-Ethyl-3-methylimidazolium-based ionic liquid with acetate [OAc], ethylsulfate [EtSO4], and methyl sulfonate [MeSO3] anions was used to generate the liquid-liquid equilibrium (LLE) data for the quaternary mixture of IL (1)-thiophene (2)-pyridine (3)-pentane (4). The selectivity and distribution coefficient values were calculated to evaluate the effectiveness of the simultaneous extraction of thiophene and pyridine from pentane at ambient conditions. The experimental tie-line data were successfully validated by the nonrandom two liquid (NRTL) and universal quasi-chemical (UNIQUAC) models, giving root mean square deviation (RMSD) values less than 1 % for all the systems. The novelty of the work was that a conductor like screening model for real solvents (COSMO-RS) model was used to predict compositions of quaternary systems. However, it failed to reproduce the slope of the tie-lines at high solute concentration, especially for the ionic liquid rich phase. The COSMO-RS predictions gave a RMSD of 4.62 % ([EMIM][OAc]), 5.3 % ([EMIM][EtSO 4]), and 6.07 % ([EMIM][MeSO3]). © 2013 American Chemical Society.

Hasima N.,University of Houston | Hasima N.,University of Malaya | Ozpolat B.,University of Houston
Cell Death and Disease | Year: 2014

Autophagy, a lysosomal degradation pathway for cellular constituents and organelles, is an adaptive and essential process required for cellular homeostasis. Although autophagy functions as a survival mechanism in response to cellular stressors such as nutrient or growth factor deprivation, it can also lead to a non-apoptotic form of programmed cell death (PCD) called autophagy-induced cell death or autophagy-associated cell death (type II PCD). Current evidence suggests that cell death through autophagy can be induced as an alternative to apoptosis (type I PCD), with therapeutic purpose in cancer cells that are resistant to apoptosis. Thus, modulating autophagy is of great interest in cancer research and therapy. Natural polyphenolic compounds that are present in our diet, such as rottlerin, genistein, quercetin, curcumin, and resveratrol, can trigger type II PCD via various mechanisms through the canonical (Beclin-1 dependent) and non-canonical (Beclin-1 independent) routes of autophagy. The capacity of these compounds to provide a means of cancer cell death that enhances the effects of standard therapies should be taken into consideration for designing novel therapeutic strategies. This review focuses on the autophagy- and cell death-inducing effects of these polyphenolic compounds in cancer. © 2014 Macmillan Publishers Limited All rights reserved.

Hasima N.,University of Houston | Hasima N.,University of Malaya | Aggarwal B.B.,University of Houston
Current Medicinal Chemistry | Year: 2014

Curcumin, a major component of the golden spice turmeric (Curcuma longa), has been linked with the prevention and treatment of a wide variety of cancers through modulation of multiple cell signaling pathways. Since the first report from our laboratory in 1995 that curcumin can inhibit activation of the proinflammatory transcription factor NF-B by inhibiting the 26S proteasomal degradation of IB, an inhibitor of NF-B, this yellow pigment has been shown to inhibit the protease activities of the proteasome. The carbonyl carbons of the curcumin molecule directly interact with the hydroxyl group of the amino-terminal threonine residue of the proteasomal CT-L subunit of 20S proteasome and cellular 26S proteasome. Curcumin is also a potent inhibitor of COP9 signalosome and associated kinases, casein kinase 2 and protein kinase D, all linked to the ubiquitin-proteasomal system (UPS). Curcumin can also directly inhibit ubiquitin isopeptidases, a family of deubiquitinases (DUBs) that salvage ubiquitin for reuse by the 26S proteasome system. The inhibition of this enzyme by curcumin is mediated through ,-unsaturated ketone and two sterically accessible -carbons. Regulation of the UPS pathway by curcumin has been linked to regulation of cancer-linked inflammatory proteins (such as COX-2 and iNOS), transcription factors (NF-B, STAT3, Sp, AP-1, GADD153/CHOP, HIF-1), growth factors (VEGF, HER2), apoptotic proteins (p53, Bcl-2, survivin, DNA topoisomerase II, HDAC2, p300, hTERT) and cell cycle proteins (cyclin D1, cyclin E, cyclin B, p21, p27) associated with the prevention and therapy of cancer. Interestingly, the effect of curcumin on 26S proteasome appears to be dose-dependent, as low doses (1 M) increase proteasome activity whereas high doses (10 M) inhibit the proteasome activity. In this review, we discuss in detail how modulation of these targets by curcumin is linked to prevention and treatment of cancer. © 2014 Bentham Science Publishers.

Teh C.Y.,University of Selangor | Wu T.Y.,University of Selangor | Juan J.C.,University of Malaya
Ecological Engineering | Year: 2014

The present study investigated the use of starch to replace inorganic coagulants for the treatment of agro-industrial wastewater from palm oil mill, namely palm oil mill effluent (POME). Rice starch was found to be the best starch because it yielded similar total suspended solids (TSS) removal as alum, significantly shortened the settling time and produced flocs with higher resistance towards stronger shear force. The use of rice starch alone in room temperature enabled the removal of TSS up to 84.1% using the recommended values of dosage, initial pH, settling time and slow stirring speed at 2. g/L, pH 3, 5. min and 10. rpm, respectively. Higher TSS removal of 88.4% could still be achieved at lower dosage of rice starch (0.55. g/L) only when rice starch was used together with 0.2. g/L of alum during the treatment of POME. To gain further insights on the properties of coagulants and flocs produced from the treatment, characterization methods such as Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) were used. © 2014 Elsevier B.V.

Law J.W.-F.,University of Selangor | Mutalib N.-S.A.,University of Malaya | Chan K.-G.,University of Malaya | Lee L.-H.,University of Selangor
Frontiers in Microbiology | Year: 2014

The incidence of foodborne diseases has increased over the years and resulted in major public health problem globally. Foodborne pathogens can be found in various foods and it is important to detect foodborne pathogens to provide safe food supply and to prevent foodborne diseases. The conventional methods used to detect foodborne pathogen are time consuming and laborious. Hence, a variety of methods have been developed for rapid detection of foodborne pathogens as it is required many food analyses. Rapid detection methods can be categorized into nucleic acid-based, biosensor-based and immunological-based methods. This review emphasizes on the principles and application of recent rapid methods for the detection of foodborne bacterial pathogens. Detection methods included are simple polymerase chain reaction (PCR), multiplex PCR, real-time PCR, nucleic acid sequence-based amplification (NASBA), loop-mediated isothermal amplification LAMP) and oligonucleotide DNA microarray which classified as nucleic acid-based methods; optical, electrochemical and mass-based biosensors which classified as biosensor-based methods; enzyme-linked immunosorbent assay (ELISA) and lateral flow immunoassay which classified as immunological-based methods. In general, rapid detection methods are generally time-efficient, sensitive, specific and labor-saving. The developments of rapid detection methods are vital in prevention and treatment of foodborne diseases. © 2014 Jodi-woan-fei, Ab-mutalib, Chan and Lee.

Chong P.-P.,University of Malaya | Selvaratnam L.,University of Selangor | Abbas A.A.,University of Malaya | Kamarul T.,University of Malaya
Journal of Orthopaedic Research | Year: 2012

The use of mesenchymal stem cells (MSCs) for cartilage repair has generated much interest owing to their multipotentiality. However, their significant presence in peripheral blood (PB) has been a matter of much debate. The objectives of this study are to isolate and characterize MSCs derived from PB and, compare their chondrogenic potential to MSC derived from bone marrow (BM). PB and BM derived MSCs from 20 patients were isolated and characterized. From 2 ml of PB and BM, 5.4 ± 0.6 million and 10.5 ± 0.8 million adherent cells, respectively, were obtained by cell cultures at passage 2. Both PB and BM derived MSCs were able to undergo tri-lineage differentiation and showed negative expression of CD34 and CD45, but positively expressed CD105, CD166, and CD29. Qualitative and quantitative examinations on the chondrogenic potential of PB and BM derived MSCs expressed similar cartilage specific gene (COMP) and proteoglycan levels, respectively. Furthermore, the s-GAG levels expressed by chondrogenic MSCs in cultures were similar to that of native chondrocytes. In conclusion, this study demonstrates that MSCs from PB maintain similar characteristics and have similar chondrogenic differentiation potential to those derived from BM, while producing comparable s-GAG expressions to chondrocytes. Copyright © 2011 Orthopaedic Research Society.

Hasima N.,University of Houston | Hasima N.,University of Malaya | Aggarwal B.B.,University of Houston
International Journal of Biochemistry and Molecular Biology | Year: 2012

In spite of major advances in oncology, the World Health Organization predicts that cancer incidence will double within the next two decades. Although it is well understood that cancer is a hyperproliferative disorder mediated through dysregulation of multiple cell signaling pathways, most cancer drug development remains focused on modulation of specific targets, mostly one at a time, with agents referred to as "targeted therapies," "smart drugs," or "magic bullets." How many cancer targets there are is not known, and how many targets must be attacked to control cancer growth is not well understood. Although more than 90% of cancer-linked deaths are due to metastasis of the tumor to vital organs, most drug targeting is focused on killing the primary tumor. Besides lacking specificity, the targeted drugs induce toxicity and side effects that sometimes are greater problems than the disease itself. Furthermore, the cost of some of these drugs is so high that most people cannot afford them. The present report describes the potential anticancer properties of curcumin, a component of the Indian spice turmeric (Curcuma longa), known for its safety and low cost. Curcumin can selectively modulate multiple cell signaling pathways linked to inflammation and to survival, growth, invasion, angiogenesis, and metastasis of cancer cells. More clinical trials of curcumin are needed to prove its usefulness in the cancer setting.

Khan A.U.R.,University of Malaya | Othman M.,University of Malaya | Madani S.A.,COMSATS Institute of Information Technology | Khan S.U.,North Dakota State University
IEEE Communications Surveys and Tutorials | Year: 2014

Smartphones are now capable of supporting a wide range of applications, many of which demand an ever increasing computational power. This poses a challenge because smartphones are resource-constrained devices with limited computation power, memory, storage, and energy. Fortunately, the cloud computing technology offers virtually unlimited dynamic resources for computation, storage, and service provision. Therefore, researchers envision extending cloud computing services to mobile devices to overcome the smartphones constraints. The challenge in doing so is that the traditional smartphone application models do not support the development of applications that can incorporate cloud computing features and requires specialized mobile cloud application models. This article presents mobile cloud architecture, offloading decision affecting entities, application models classification, the latest mobile cloud application models, their critical analysis and future research directions. © 2014 IEEE.

Anantharaj R.,University of Malaya | Banerjee T.,Indian Institute of Technology Guwahati
AIChE Journal | Year: 2013

The tie-line composition of three quaternary system namely 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]) ([EMIM][OAc]) (1)+thiophene (2)+pyridine (3)+toluene (4), 1-ethyl-3-methylimidazolium ethylsulphate ([EMIM][EtSO4]) (1)+thiophene (2)+pyridine (3)+toluene (4), 1-ethyl-3-methylimidazolium methylsulphonate ([EMIM][MeSO3]) (1)+thiophene (2)+pyridine (3)+toluene (4) were experimentally determined at 298.15 K. The measured tie-line data were successfully correlated with the nonrandom two liquid and UNIversal QUAsiChemical model prediction which gave less than 1% root mean square deviation (RMSD). [EMIM][MeSO3] looks to be a promising solvent for the simultaneous separation having distribution ratios less than unity for both thiophene and pyridine. The quantum chemical-based conductor like screening model for real solvent (COSMO-RS) model was then used to predict the tie-line composition of quaternary systems. COSMO-RS gave the RMSD for the studied systems to be 8.41, 8.74, and 6.53% for the ionic liquids, respectively. © 2013 American Institute of Chemical Engineers.

Teh C.Y.,University of Selangor | Wu T.Y.,University of Selangor | Juan J.C.,University of Malaya
Industrial Crops and Products | Year: 2014

There have been increasing interests on the use of organic starch derivative coagulants such as cationic starch in coagulation-flocculation process due to environment and health concerns regarding the use of inorganic coagulants. However, studies on the potential utilization of unmodified starch in wastewater treatment remain limited. In this study, treatment performance of unmodified rice starch and alum was tested on agro-industrial wastewater produced from crude palm oil extraction, namely palm oil mill effluent (POME). Response surface methodology (RSM) showed that an addition of unmodified rice starch not only enhanced total suspended solids (TSS) and chemical oxygen demand (COD) removals; but it also significantly improved the process by reducing both the dosage of alum (-47.95%) and settling time (-58.66%), while shifting the operating pH closer to the natural pH of POME. The treatment enabled TSS and COD removals up to 86.65 and 49.23%, respectively under the optimum conditions of 0.38. g/L alum, 0.28. g/L unmodified rice starch, pH 4.45 and settling time of 5.54. min. An addition of unmodified rice starch to alum also resulted in 33.8% reduction of chemical cost as compared to the treatment using alum alone. © 2014 Elsevier B.V.

Olofsson T.,Umeå University | Mahlia T.M.I.,University of Malaya | Mahlia T.M.I.,University of Syiah Kuala
Applied Energy | Year: 2012

In order to reduce the energy use in the building sector there is a demand for tools that can identify significant building energy performance parameters. In the work introduced in this paper presents a methodology, based on a simulation module and graphical figures, for interactive investigations of the building energy performance. The building energy use simulation program is called TEKLA and is using EN832 with an improved procedure in calculating the heat loss through the floor and the solar heat gain. The graphical figures are simple and are illustrating the savings based on retrofit measures and climate conditions.The accuracy of the TEKLA simulation was investigated on a typical single-family building in Sweden for a period of time in a space heating demand of relatively cold and mild climate. The model was found applicable for relative investigations. Further, the methodology was applied on a typical single family reference building. The climate data from three locations in Sweden were collected and a set of relevant measures were studied. The investigated examples illustrate how decisions in the early stages of the building design process can have decisive importance on the final building energy performance. © 2011 Elsevier Ltd.

Saidur R.,University of Malaya | Abdelaziz E.A.,University of Malaya | Demirbas A.,Sirnak University | Hossain M.S.,University of Malaya | Mekhilef S.,University of Kuala Lumpur
Renewable and Sustainable Energy Reviews | Year: 2011

Currently, fossil fuels such as oil, coal and natural gas represent the prime energy sources in the world. However, it is anticipated that these sources of energy will deplete within the next 40-50 years. Moreover, the expected environmental damages such as the global warming, acid rain and urban smog due to the production of emissions from these sources have tempted the world to try to reduce carbon emissions by 80% and shift towards utilizing a variety of renewable energy resources (RES) which are less environmentally harmful such as solar, wind, biomass etc. in a sustainable way. Biomass is one of the earliest sources of energy with very specific properties. In this review, several aspects which are associated with burning biomass in boilers have been investigated such as composition of biomass, estimating the higher heating value of biomass, comparison between biomass and other fuels, combustion of biomass, co-firing of biomass and coal, impacts of biomass, economic and social analysis of biomass, transportation of biomass, densification of biomass, problems of biomass and future of biomass. It has been found that utilizing biomass in boilers offers many economical, social and environmental benefits such as financial net saving, conservation of fossil fuel resources, job opportunities creation and CO 2 and NOx emissions reduction. However, care should be taken to other environmental impacts of biomass such as land and water resources, soil erosion, loss of biodiversity and deforestation. Fouling, marketing, low heating value, storage and collections and handling are all associated problems when burning biomass in boilers. The future of biomass in boilers depends upon the development of the markets for fossil fuels and on policy decisions regarding the biomass market. © 2011 Elsevier Ltd. All rights reserved.

Abdullah W.H.,University of Malaya | Shalaby M.R.,Tanta University
GeoArabia | Year: 2011

In this paper, organic matter content, type and maturity as well as some petrographic characteristics of the Jurassic shales exposed in the Masila Basin were evaluated and their depositional environments were interpreted using organic geochemical and organic petrological studies. The total organic carbon (TOC) contents of shales in the Sunah, Wadi Taribah, and Kharir fields vary between 2.4% and 4.7% with high Hydrogen Index (HI) values. All shale samples display very low Oxygen Index (OI) values. The Sunah and Wadi Taribah shales contain Type II organic matter, while the Kharir shales contain Type II, with minor contributions from Type I organic matter. Tmax values for the shales range from 428 °C to 438 °C and vitrinite reflectance values (%Ro) range from 0.52% to 0.80%. These values reveal that the Sunah and Kharir shales are at peak mature stage while the Wadi Taribah shales are early mature. This is supported by their biomarker maturity parameters. The pristane/phytane (Pr/Ph) ratios range from 1.8 to 2.3. In addition, all shales show a homohopane distribution which is dominated by low carbon numbers, and C35homohopane index is very low for all shale samples. All these features may indicate that these shales were deposited in a suboxic environment. Sterane distribution was calculated as C27>C29> C28 from the m/z 217 mass chromatogram for all shale samples. The Sunah, Wadi Taribah and Kharir shales are believed to have good oil generating potential. This is supported by high total organic carbon content, hydrogen indices up to 400 mg HC/g TOC and early to peak mature oil window range.

Samuel V.B.,University of Malaya | Agamuthu P.,University of Kuala Lumpur | Hashim M.A.,University of Kuala Lumpur
Ecological Indicators | Year: 2013

The primary objective of this study was to provide an insight into sustainable production indicators used by the petrochemical industry in Malaysia to measure the sustainability of the industry's operations. In achieving the research objective, the case study method was employed. The petrochemical industry was selected because of its major contribution to the Malaysian economy (market share and total investment), its significant impacts to the environment and, high societal and occupational risks. The sector is also highly dependent on non-renewable fossil fuels such as natural gas, LPG and diesel; and is energy intensive. Utilising the five-tier framework developed by the Lowell Centre for Sustainable Production (LCSP) and indicators identified by the Global Reporting Initiative (GRI) Guidelines 3.1, an analysis of indicators used by the petrochemical sector was carried out. The LCSP framework was selected as it is an established framework and has been successfully used in similar case studies in other parts of the world. Furthermore, at present there is no common framework in Malaysia to assess sustainable production at the industrial level. Under the GRI guidelines, performance indicators have been grouped into six categories. The six categories include Environment (EN1-EN30), Economic (EC1-EC9), Society (SO1-SO8), Human Rights (HR1-HR9), Labour Practices and Decent Work (LA1-LA14) and Product Responsibility (PR1-PR9). The study was carried out using the questionnaire survey method and supplemented with semi-structured in-depth interviews. To ensure their suitability and applicability in the Malaysian context, the indicators selected for the study were based on feedback obtained from the participating companies. An analysis of the information obtained from the participating companies indicates the satisfactory performance of the petrochemical industry in employing most of the indicators identified within the GRI framework to advance towards sustainability. Results indicate that the majority of the indicators monitored are related to compliance (Level 1), performance (Level 2) and environmental impacts (Level 3). The single Level 4 indicator which relates to products and services was weakly monitored (38.5%). None of the indicators monitored fell within Level 5 category which addresses sustainability issues in terms of the ecological carrying capacity. The Level 5 indicators which assess sustainability in a community or regional context can only be effectively implemented once the necessary policies and regulations are in place; and with greater awareness and cooperation between the regulators and stakeholders. © 2012 Elsevier Ltd. All rights reserved.

Tee M.Y.,University of Malaya | Karney D.,University of Kansas
International Journal of Computer-Supported Collaborative Learning | Year: 2010

Research on knowledge cultivation often focuses on explicit forms of knowledge. However, knowledge can also take a tacit form-a form that is often difficult or impossible to tease out, even when it is considered critical in an educational context. A review of the literature revealed that few studies have examined tacit knowledge issues in online learning environments. The purpose of this study was to develop a greater understanding of the conditions and processes that help promote the sharing or cultivation of tacit knowledge in a formal online course setting. Using naturalistic inquiry as the methodology of this study, an online graduate business course offered at a private, non-profit United States-based university was purposively selected as the research site. The study found that the online course encouraged processes and created conditions consistent with Nonaka's model of knowledge creation and the concept of ba (or shared context)-encouraging students to share, and to construct knowledge through socialization, externalization, combination, and internalization. The results suggest that purposefully developing a ba-like environment may be a useful approach to facilitating online learning, creating a strong potential to support learning processes necessary for students to cultivate tacit knowledge. © 2010 International Society of the Learning Sciences, Inc.; Springer Science + Business Media, LLC.

Behnia A.,University of Malaya | Chai H.K.,University of Malaya | Shiotani T.,Kyoto University
Construction and Building Materials | Year: 2014

This article gives a comprehensive review of the acoustic emission (AE) technique for its applications in concrete structure health monitoring. Basic and established condition assessment methods for concrete structures are reviewed to configure a firm perception of AE application for enhanced performance and reliability. The AE approaches of focus are the parametric and signal analysis which can be used to develop damage evaluation criteria. Other than recent localization and source discrimination methods, applications of pivotal AE parameters such as b-value, Ib-value, AE energy, and hit are discussed herein, with highlights on the limitation of the individual parameter-based approaches when adopted on site. In addition, the introduction of new parameters such as sifted b-value, minimum b-value, and Q value is discussed as well, followed by a novel recent strategy for AE application in conjunction with tomography method to facilitate infrastructure assessment. Moreover, the key role of application of artificial intelligence methods towards damage mode identification has been highlighted. © 2014 Elsevier Ltd. All rights reserved.

Herat S.,Griffith University | Agamuthu P.,University of Malaya
Waste Management and Research | Year: 2012

Safe management of electronic and electrical waste (e-waste/WEEE) is becoming a major problem for many countries around the world. In particular, developing countries face a number of issues with the generation, transboundary movement and management of e-waste. It is estimated that the world generates around 20-50 million tonnes of e-waste annually, most of it from Asian countries. Improper handling of e-waste can cause harm to the environment and human health because of its toxic components. Several countries around the world are now struggling to deal with this emerging threat. Although the current emphasis is on end-of-life management of e-waste activities, such as reuse, servicing, remanufacturing, recycling and disposal, upstream reduction of e-waste generation through green design and cleaner production is gaining much attention. Environmentally sound management (ESM) of e-waste in developing countries is absent or very limited. Transboundary movement of e-waste is a major issue throughout the region. Dealing with the informal recycling sector is a complex social and environmental issue. There are significant numbers of such challenges faced by these countries in achieving ESM of e-waste. This article aims to present a review of challenges and issues faced by Asian countries in managing their e-waste in a sustainable way. © The Author(s) 2012.

Yong F.L.,University of Malaya | Law C.W.,University of Malaya | Wang C.W.,University of Kuala Lumpur
BMC Cancer | Year: 2013

Background: MicroRNAs (miRNAs) are short, non-coding RNA molecules that act as regulators of gene expression. Circulating blood miRNAs offer great potential as cancer biomarkers. The objective of this study was to correlate the differential expression of miRNAs in tissue and blood in the identification of biomarkers for early detection of colorectal cancer (CRC).Methods: The study was divided into two phases: (I) Marker discovery by miRNA microarray using paired cancer tissues (n = 30) and blood samples (CRC, n = 42; control, n = 18). (II) Marker validation by stem-loop reverse transcription real time PCR using an independent set of paired cancer tissues (n = 30) and blood samples (CRC, n = 70; control, n = 32). Correlation analysis was determined by Pearson's test. Logistic regression and receiver operating characteristics curve analyses were applied to obtain diagnostic utility of the miRNAs.Results: Seven miRNAs (miR-150, miR-193a-3p, miR-23a, miR-23b, miR-338-5p, miR-342-3p and miR-483-3p) have been found to be differentially expressed in both tissue and blood samples. Significant positive correlations were observed in the tissue and blood levels of miR-193a-3p, miR-23a and miR-338-5p. Moreover, increased expressions of these miRNAs were detected in the more advanced stages. MiR-193a-3p, miR-23a and miR-338-5p were demonstrated as a classifier for CRC detection, yielding a receiver operating characteristic curve area of 0.887 (80.0% sensitivity, 84.4% specificity and 83.3% accuracy).Conclusion: Dysregulations in circulating blood miRNAs are reflective of those in colorectal tissues. The triple miRNA classifier of miR-193a-3p, miR-23a and miR-338-5p appears to be a potential blood biomarker for early detection of CRC. © 2013 Yong et al.; licensee BioMed Central Ltd.

Ho C.C.K.,University of Kuala Lumpur | Tan H.M.,University of Malaya
Current Urology Reports | Year: 2011

Herbal medicine long has been used in the management of sexual dysfunction, including erectile dysfunction. Many patients have attested to the efficacy of this treatment. However, is it evidence-based medicine? Studies have been done on animal models, mainly in the laboratory. However, randomized controlled trials on humans are scarce. The only herbal medications that have been studied for erectile dysfunction are Panax ginseng, Butea superba, Epimedium herbs (icariin), Tribulus terrestris, Securidaca longipedunculata, Piper guineense, and yohimbine. Of these, only Panax ginseng, B. superb, and yohimbine have published studies done on humans. Unfortunately, these published trials on humans were not robust. Many herbal therapies appear to have potential benefits, and similarly, the health risks of various phytotherapeutic compounds need to be elucidated. Properly designed human trials should be worked out and encouraged to determine the efficacy and safety of potential phytotherapies. © 2011 Springer Science+Business Media, LLC.

Zamani-Farahani H.,University of Malaya | Henderson J.C.,Nanyang Technological University
International Journal of Tourism Research | Year: 2010

This paper is concerned with the effects of state religion on tourism development in Muslim countries with particular reference to Iran and Saudi Arabia. Aspects of the relationship between Islam and tourism are investigated overall and issues of tourism policies, management and marketing and community involvement within the context of the two cases are discussed. The distinctive circumstances prevailing in Iran and Saudi Arabia are suggested, but more general insights are also presented into the interactions between and management of tourism and Islam. Copyright © 2009 John Wiley & Sons, Ltd.

Polgar G.,University of Malaya | Bartolino V.,Institute of Marine Research
Marine Ecology Progress Series | Year: 2010

Reduction in size from sea to land is a common trend of many fish species and communities, at both the intraspecific and interspecific level. Within the intertidal zone, similar trends have been described at the intraspecific level in several transient and resident fish species. Oxudercines are a group of intertidal gobies (Gobiidae: Oxudercinae) including several species, which exhibit extreme adaptations to an amphibious lifestyle. Ecomorphological and ecophysiological considerations suggest that size reduction in this group may have facilitated the adaptation to semi-terrestrial conditions. To test this hypothesis, the spatial ecology and the presence of an intra- and interspecific size gradient was investigated in an oxudercine community of a Malayan intertidal ecosystem (6 species included in 3 genera). A random stratified sampling design was adopted, and ANOVA and cluster analysis performed to describe this variation. Multivariate analyses of the quantity of environmental water were also conducted to investigate the correspondence between size and habitat terrestriality. Larger species were found in more aquatic conditions at lower topographical levels along the vertical intertidal gradient, supporting the hypothesis of an adaptive value of smaller size in more terrestrial habitats. Intraspecific variation showed more complex patterns, even if in several species smaller individuals were found in more terrestrial conditions. © Inter-Research 2010.

Lawal S.A.,University of Malaya | Lawal S.A.,Minna Federal University Of Technology | Choudhury I.A.,University of Malaya | Nukman Y.,University of Malaya
International Journal of Machine Tools and Manufacture | Year: 2012

The increasing attention to the environmental and health impacts of industrial activities by governmental regulations and by the growing awareness level in the society is forcing industrialists to reduce the use of mineral oil-based metalworking fluids as cutting fluid. Cutting fluids have been used extensively in metal cutting operations for the last 200 years. In the beginning, cutting fluids consisted of simple oils applied with brushes to lubricate and cool the machine tool. As cutting operations became more severe, cutting fluid formulations became more complex. There are now several types of cutting fluids in the market and the most common types can be broadly categorized as cutting oils or water-miscible fluids. In this review, the applicability of vegetable oil-based metalworking fluids in machining of ferrous metals has been undertaken. The advantages of metalworking fluids and its performances with respect to the cutting force, surface finish of work piece, tool wear and temperature at the cutting zone have been investigated. It has been reported in various literature that metalworking fluids, which are vegetable oil-based, could be an environmentally friendly mode of machining with similar performance obtained using mineral oil-based metalworking fluids. © 2011 Elsevier Ltd. Allrightsreserved.

Waran V.,University of Malaya | Narayanan V.,University of Malaya | Karuppiah R.,University of Malaya | Owen S.L.F.,University of Portsmouth | Aziz T.,University of Oxford
Journal of Neurosurgery | Year: 2014

The advent of multimaterial 3D printers allows the creation of neurosurgical models of a more realistic nature, mimicking real tissues. The authors used the latest generation of 3D printer to create a model, with an inbuilt pathological entity, of varying consistency and density. Using this model the authors were able to take trainees through the basic steps, from navigation and planning of skin flap to performing initial steps in a craniotomy and simple tumor excision. As the technology advances, models of this nature may be able to supplement the training of neurosurgeons in a simulated operating theater environment, thus improving the training experience. ©AANS, 2014.

Ooi C.H.R.,University of Malaya | Ho W.,University of Malaya | Bandrauk A.D.,Université de Sherbrooke
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

We study the characteristics of ionization rates of an atom by an intense laser field using an extension of Keldysh theory. High-order semianalytical expressions are obtained for linear, circular, and elliptically polarized fields. We compare the features of the new rates with Keldysh analytical results as functions of frequency and electric field strength. The directionality of photoelectron emissions is compared for elliptical, circular, and linearly polarized cases. Laser polarization has significant effects on the ionization spectra and directionality of photoelectron emission. © 2012 American Physical Society.

Champiri Z.D.,University of Malaya | Shahamiri S.R.,Manukau Institute of Technology | Salim S.S.B.,University of Malaya
Expert Systems with Applications | Year: 2015

Incorporating contextual information in recommender systems is an effective approach to create more accurate and relevant recommendations. This review has been conducted to identify the contextual information and methods used for making recommendations in digital libraries as well as the way researchers understood and used relevant contextual information from the years 2001 to 2013 based on the Kitchenham systematic review methodology. The results indicated that contextual information incorporated into recommendations can be categorised into three contexts, namely users' context, document's context, and environment context. In addition, the classical approaches such as collaborative filtering were employed more than the other approaches. Researchers have understood and exploited relevant contextual information through four ways, including citation of past studies, citation of past definitions, self-definitions, and field-query researches; however, citation of the past studies has been the most popular method. This review highlights the need for more investigations on the concept of context from user viewpoint in scholarly domains. It also discusses the way a context-aware recommender system can be effectively designed and implemented in digital libraries. Additionally, a few recommendations for future investigations on scholarly recommender systems are proposed. © 2014 Elsevier Ltd. All rights reserved.

Gumel A.M.,University of Malaya | Annuar M.S.M.,University of Malaya | Chisti Y.,Massey University
Journal of Polymers and the Environment | Year: 2013

Polyhydroxyalkanoates (PHAs) are biodegradable and biocompatible polyesters that can potentially replace certain plastics derived from petroleum. PHAs can be produced using a combination of renewable feedstocks and biological methods. Native and recombinant microorganisms have been generally used for making PHAs via fermentation processes. As much as 90 % of the microbial dry mass may accumulate as PHAs. A range of PHAs has been produced using fermentation methods, including copolymers and block copolymers. Alternative production schemes based on genetically modified plants are becoming established and may become the preferred route for producing certain PHAs. Production in plants is likely to be inexpensive compared to production by fermentation, but it does not appear to be as versatile as microbial synthesis in terms of the range of products that may be generated. Cell-free enzymatic production of PHAs in vitro is receiving increasing attention and may become the preferred route to some specialty products. This review discusses the recent advances in production of polyhydroxyalkanoates by the various methods. Methods of recovering the polymer from microbial biomass are reviewed. Established and emerging applications of PHAs are discussed. © 2012 Springer Science+Business Media, LLC.

Lim S.-L.,University of Malaya | Chu W.-L.,International Medical University | Phang S.-M.,University of Malaya
Bioresource Technology | Year: 2010

The potential application of Chlorella vulgaris UMACC 001 for bioremediation oftextile wastewater (TW) was investigated using four batches of cultures in high rate algae ponds (HRAP) containing textile dye (Supranol Red 3BW) or TW. The biomass attained ranged from 0.17 to 2.26 mg chlorophyll a/L while colour removal ranged from 41.8% to 50.0%. There was also reduction of NH4-N (44.4-45.1%), PO4-P (33.1-33.3%) and COD (38.3-62.3%) in the TW. Supplementation of the TW with nutrients of Bold's Basal Medium (BBM) increased biomass production but did not improve colour removal or reduction of pollutants. The mechanism of colour removal by C.vulgaris is biosorption, in accordance with both the Langmuir and Freundlich models. The HRAPusing C. vulgaris offers a good system for the polishing of TW before final discharge. © 2010 Elsevier Ltd. All rights reserved.

Gumel A.M.,University of Malaya | Annuar M.S.M.,University of Malaya | Chisti Y.,Massey University
Ultrasonics Sonochemistry | Year: 2013

Four different lipases were compared for ultrasound-mediated synthesis of the biodegradable copolymer poly-4-hydroxybutyrate-co-6-hydroxyhexanoate. The copolymerization was carried out in chloroform. Of the enzymes tested, Novozym 435 exhibited the highest copolymerization rate, in fact the reaction rate was observed to increase with about 26-fold from 30 to 50 °C (7.9 × 10-3 M s-1), sonic power intensity of 2.6 × 10 3 W m-2 and dissipated energy of 130.4 J ml-1. Copolymerization rates with the Candida antarctica lipase A, Candida rugosa lipase, and Lecitase Ultra™ were lower at 2.4 × 10-4, 1.3 × 10-4 and 3.5 × 10-4 M s-1, respectively. The catalytic efficiency depended on the enzyme. The efficiency ranged from 4.15 × 10-3 s-1 M-1 for Novozym 435-1.48 × 10-3 s-1 M-1 for C. rugosa lipase. Depending on the enzyme and sonication intensity, the monomer conversion ranged from 8.2% to 48.5%. The sonication power, time and temperature were found to affect the rate of copolymerization. Increasing sonication power intensity from 1.9 × 103 to 4.5 × 103 W m -2 resulted in an increased in acoustic pressure (Pa) from 3.7 × 108 to 5.7 × 108 N m-2 almost 2.4-3.7 times greater than the acoustic pressure (1.5 × 10 8 N m-2) that is required to cause cavitation in water. A corresponding acoustic particle acceleration (a) of 9.6 × 10 3-1.5 × 104 m s-2 was calculated i.e. approximately 984-1500 times greater than under the action of gravity. © 2012 Elsevier B.V. All rights reserved.

Lawal S.A.,University of Malaya | Lawal S.A.,Minna Federal University Of Technology | Choudhury I.A.,University of Malaya | Nukman Y.,University of Malaya
Journal of Cleaner Production | Year: 2013

In this study, a review of the available literature on lubrication techniques during machining processes was conducted. Factors such as workpiece material, tool material and machining conditions were observed to be vital to the performance of any of the techniques. The performance and drawback of each technique were highlighted based on the machining conditions. It concludes by making a case forminimum quantity lubrication (MQL) method using vegetable oil-based lubricant in different machining processes, as a way of addressing the environmental health issues and cost associated with the application of lubricant in machining processes. © 2012 Elsevier Ltd. All rights reserved.

Cheok C.Y.,Penang Adventist Hospital | Mohamad J.A.,Selangor Specialist Hospital | Ahmad T.S.,University of Malaya
Journal of Orthopaedic Trauma | Year: 2011

Objectives: The aim was to compare the effectiveness of intra-articular lidocaine (IAL) versus intravenous Demerol and Diazepam (IVS) in reduction of acute anterior shoulder dislocation. Design: This is a prospective randomized study. Setting: Emergency room setting. Patients: Thirty-one dislocations reduced with IVS, whereas 32 patients were reduced using IAL. Main Outcome Measurements: The visual analog pain scale was used before analgesic administration and during the closed manipulative reduction. Length of time since dislocation, frequency of dislocation, ease of reduction, patient satisfaction, adverse effects, and duration of hospitalization were recorded. Results: The IVS group had a 100% success rate, whereas the IAL group had a 19% (six of 32) failure rate (P = 0.024). However, there was no significant difference in terms of pain relief (P = 0.23) or patient satisfaction (P = 0.085) between both groups. In addition, patients in the IAL group had a shorter duration of hospitalization and no reported complications, whereas the intravenous group had a longer hospital stay and a 29% complication rate. The cost of IAL was 32% less than the cost for IVS. Conclusion: IAL was more cost effective than the IVS method. IAL provided adequate pain relief and fewer complications and is a viable option for analgesia during reduction of acute shoulder dislocation. Copyright © 2010 by Lippincott Williams & Wilkins.

Hajimolana S.A.,University of Malaya | Hussain M.A.,University of Malaya | Daud W.M.A.W.,University of Malaya | Soroush M.,Drexel University | Shamiri A.,University of Malaya
Renewable and Sustainable Energy Reviews | Year: 2011

This paper presents a review of studies on mathematical modeling of solid oxide fuel cells (SOFCs) with respect to the tubular and planar configurations. In this work, both configurations are divided into five subsystems and the factors such as mass/energy/momentum transfer, diffusion through porous media, electrochemical reactions with and without CO oxidation, shift and reforming reactions, and polarization losses inside the subsystems are discussed. Using variety of fuels fed to SOFCs is issued and their effect on the system is compared briefly. A short review of solid oxide fuel cell configurations and different flow manifolding are also presented in this study. Novel models based on statistical data-driven approach existing in the literatures are considered shortly. Although many studies on solid oxide fuel cells modeling have been done, still more research needs to be done to improve the models in order to predict the fuel cell behaviors more accurately. At the end of this paper the works and studies that can be done for improving the fuel cell models is suggested and pointed by the authors. © 2010 Elsevier Ltd. All rights reserved.

Mohd Zain S.N.,University of Malaya | Behnke J.M.,University of Nottingham | Lewis J.W.,Royal Holloway, University of London
Parasites and Vectors | Year: 2012

Background: The prevalence of parasitic infections among commensal animals such as black and brown rats in many tropical countries is high and in comparison with studies on rodents in temperate climates, little is known about the community structure of their parasites. Rodent borne parasites pose threats to human health since people living in close proximity to rodent populations can be exposed to infection. Methods. The helminth community structures of two urban rat populations in Kuala Lumpur, Malaysia were investigated. The rats were from two contrasting sites in the city caught over a period of 21 months in 2000-2002. Results: Eleven species of helminth parasites comprising seven nematodes (Heterakis spumosum, Mastophorus muris, Nippostrongylus brasiliensis, Syphacia muris, Pterygodermatites tani/whartoni, Gongylonema neoplasticum, Angiostrongylus malaysiensis), three cestodes (Hymenolepis (Rodentolepis) nana, H. diminuta and Taenia taeniaeformis) and one acanthocephalan (Moniliformis moniliformis) were recovered from 346 Rattus rattus and 104 R. norvegicus from two urban sites, Bangsar and Chow Kit, during 2000-2002. Rattus rattus harboured over 60% of all helminths compared with R. norvegicus, although both host species played a dominant role in the different sites with, for example R. norvegicus at Bangsar and R. rattus at Chow Kit accounting for most of the nematodes. Overall 80% of rats carried at least one species of helminth, with the highest prevalences being shown by H. diminuta (35%), H. spumosum (29.8%) and H. nana (28.4%). Nevertheless, there were marked differences in prevalence rates between sites and hosts. The influence of extrinsic (year, season and site) and intrinsic (species, sex and age) factors affecting infracommunity structure (abundance and prevalence of infection) and measures of component community structure were analyzed. Conclusions: Since at least two species of rat borne helminths in Kuala Lumpur have the potential to infect humans, and these showed high prevalences in the rats, the assessment and regular monitoring of infections carried by wild rodents have important roles to play in public health. © 2012 Mohd Zain et al; licensee BioMed Central Ltd.

Mahlia T.M.I.,University of Malaya | Iqbal A.,University of Malaya | Iqbal A.,State Electrical Company Ltd STELCO
Energy | Year: 2010

The demand for electricity in the Maldives continues to increase by more than 11% in recent years. This is mainly due to the growing number of high-rise air-conditioned buildings and the increasing use of electrical appliances in the residential and commercial sector. This paper investigates potential cost savings and emission reductions achieved by installing different insulation materials of optimum thickness in building's walls. The paper also investigates the effect when air gaps are introduced in the wall. The optimum insulation thickness is based on the cost benefits of each insulation material over its lifetime. This study found that by introducing optimal thickness of different insulation materials and by having air gaps of 2 cm, 4 cm and 6 cm, energy consumption and emissions can be reduced by 65-77%, in comparison to a wall without insulation or air gaps. And, hence have considerable cost savings. © 2010 Elsevier Ltd. All rights reserved.

De La Rue R.M.,University of Malaya | De La Rue R.M.,University of Glasgow | Seassal C.,École Centrale Lyon
Laser and Photonics Reviews | Year: 2012

This review article is concerned with basic aspects and some selected topics in photonic crystal (PhC) devices. It starts with a significantly historical aspect of basic principles for photonic crystals that it is hoped will help the reader to develop a critical appreciation of the research literature. It continues by describing topics such as PhC beamsplitters, slow-light structures, micro-/nanoresonators, coupled resonator optical waveguides (CROWs) and PhC-based semiconductor lasers. Emphasis is placed on both the conceptual and the practical matters that need to be addressed in order to fulfill the tasks of designing and realizing devices that exploit photonic crystal principles. The review also addresses some of the problems encountered in the fabrication of photonic crystal devices using the planar technologies of integrated photonics, which are those that are most likely to be used in future commercial production. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nguyen H.-T.,University of Malaya | Dawal S.Z.M.,University of Malaya | Nukman Y.,University of Malaya | Aoyama H.,Keio University
Expert Systems with Applications | Year: 2014

Global economic competition has spurred the manufacturing sector to improve and invest in modern equipment to satisfy the needs of the market. In particular, machine tool selection is the most important problem; it plays a primary role in the improvement of productivity and flexibility in the manufacturing environment and involves the imprecise, vague and uncertain information. This paper presents the hybrid approach of the fuzzy ANP (Analytic Network Process) and COPRAS-G (COmplex PRoportional ASsessment of alternatives with Grey relations) for fuzzy multi-attribute decision-making in evaluating machine tools with consideration of the interactions of the attributes. The fuzzy ANP is used to handle the imprecise, vague and uncertain information from expert judgments and model the interaction, feedback relationships and interdependence among the attributes to determine the weights of the attributes. COPRAS-G is employed to present the preference ratio of the alternatives in interval values with respect to each attribute and calculate the weighted priorities of the machine alternatives. Alternatives are ranked in ascending order by priority. As a demonstration of the proposed model, a numerical example is implemented based on the collected data and the literature. The result is then compared with the rankings provided by other methods such as TOPSIS-G, SAW-G and GRA. Moreover, a sensitivity analysis is conducted to verify the robustness of the ranking. The result highlights that the hybrid approach of the fuzzy ANP and COPRAS-G is a highly flexible tool and reaches an effective decision in machine tool selection. © 2013 Elsevier Ltd. All rights reserved.

Berman P.R.,University of Michigan | Ooi C.H.R.,University of Malaya
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

The propagation of a weak-field pulse through a medium of three-level atoms is considered. Each atom has a Λ-type level scheme in which the two lower levels are stable. A strong control field drives one of the electronic transitions while the signal field drives the coupled transition under conditions where EIT (electromagnetically induced transparency) is usually operative. The input pulse is slowed and compressed as it enters the medium, adiabatically following the EIT solution. However, if the control field is changed suddenly when the pulse is in the medium, the signal field is transformed into two pulses, one of which propagates as a normal EIT pulse and the other with a different speed and an amplitude that oscillates in time. The temporal oscillations are transformed into both spatial and temporal oscillations as the pulse exits the medium. An analytic expression is derived for the pulse intensity which provides a good approximation to the exact result at all times. It is shown that the oscillating component of the exiting pulse can be spatially compressed in comparison with the input pulse. © 2012 American Physical Society.

Tang W.S.,Bayan Baru Health Clinic | Khoo E.M.,University of Malaya
Journal of Sexual Medicine | Year: 2011

Introduction. Premature ejaculation (PE) is common. However, it has been underreported and undertreated. Aims. To determine the prevalence of PE and to investigate possible associated factors of PE. Methods. This cross-sectional study was conducted at a primary care clinic over a 3-month period in 2008. Men aged 18-70 years attending the clinic were recruited, and they completed self-administered questionnaires that included the Premature Ejaculation Diagnostic Tool (PEDT), International Index of Erectile Function, sociodemography, lifestyle, and medical illness. The operational definition of PE included PE and probable PE based on the PEDT. Main Outcome Measure. Prevalence of PE. Results. A total of 207 men were recruited with a response rate of 93.2%. There were 97 (46.9%) Malay, 57 (27.5%) Chinese, and 53 (25.6%) Indian, and their mean age was 46.0±12.7 years. The prevalence of PE was 40.6% (N=82) (PE: 20.3%, probable PE: 20.3% using PEDT). A significant association was found between ethnicity and PE (Indian 49.1%, Malay 45.4%, and Chinese 24.6%; χ2=8.564, d.f.=2, P=0.014). No significant association was found between age and PE. Multivariate analysis showed that erectile dysfunction (adjusted odds ratio [OR] 4.907, 95% confidence interval [CI] 2.271, 10.604), circumcision (adjusted OR 4.881, 95% CI 2.346, 10.153), sexual intercourse ≤5 times in 4 weeks (adjusted OR 3.733, 95% CI 1.847, 7.544), and Indian ethnicity (adjusted OR 3.323, 95% CI 1.489, 7.417) were predictors of PE. Conclusion. PE might be frequent in men attending primary care clinics. We found that erectile dysfunction, circumcision, Indian ethnicity, and frequency of sexual intercourse of ≤5 times per month were associated with PE. These associations need further confirmation. © 2011 International Society for Sexual Medicine.

Hayyan M.,University of Malaya | Hashim M.A.,University of Malaya | Alnashef I.M.,Masdar Institute of Science and Technology
Chemical Reviews | Year: 2016

Superoxide ion (O2 •-) is of great significance as a radical species implicated in diverse chemical and biological systems. However, the chemistry knowledge of O2 •- is rather scarce. In addition, numerous studies on O2 •- were conducted within the latter half of the 20th century. Therefore, the current advancement in technology and instrumentation will certainly provide better insights into mechanisms and products of O2 •- reactions and thus will result in new findings. This review emphasizes the state-of-the-art research on O2 •- so as to enable researchers to venture into future research. It comprises the main characteristics of O2 •- followed by generation methods. The reaction types of O2 •- are reviewed, and its potential applications including the destruction of hazardous chemicals, synthesis of organic compounds, and many other applications are highlighted. The O2 •- environmental chemistry is also discussed. The detection methods of O2 •- are categorized and elaborated. Special attention is given to the feasibility of using ionic liquids as media for O2 •-, addressing the latest progress of generation and applications. The effect of electrodes on the O2 •- electrochemical generation is reviewed. Finally, some remarks and future perspectives are concluded. © 2016 American Chemical Society.

News Article | April 20, 2016
Site: phys.org

A team of researchers from the University of Malaya in Kuala Lumpur, Malaysia, discovered it while surveying aquatic stages of black flies in Indonesia. In total, they collected nine species, and two of them were new to science, although only one is described in the JME paper. The new species, Simulium kalimantanense, was named in honor of the Indonesian state of Kalimantan, where it was discovered. The biology and behavioral habits of S. kalimantanense, including whether or not it bites humans or other animals, are yet unknown. "This is a new species, so its biting habits remain unknown," said Dr. Hiroyuki Takaoka, one of the authors. "One species, Simulium asakoae, of the subgenus Gomphostilbia, to which this new species belongs, is known to be a vector of an unknown filariasis—a parasitic disease caused by infection with roundworms—and it probably parasitizes birds. So there is a possibility of this new species carrying some roundworms that can infect wild mammals or birds." The new fly is the first known member of the Simulium (Gomphostilbia) banauense species-group to be found in Borneo. A complete description of the new species, along with a key for identifying the 19 Bornean species in the subgenus Gomphostilbia, is provided in the article. Explore further: New sand fly species discovered in Brazil More information: A New Species of Simulium (Gomphostilbia) (Diptera: Simuliidae) From Kalimantan, Indonesia, With Keys to Identify 19 Bornean Species of the Subgenus Gomphostilbia , DOI: 10.1093/jme/tjw017 , http://jme.oxfordjournals.org/content/early/2016/04/18/jme.tjw017

Jamali H.,University of Malaya | Radmehr B.,Islamic Azad University at Karaj
Veterinary Journal | Year: 2013

The aims of this study were to determine the prevalence, characteristics and antimicrobial resistance of Listeria spp. isolated from bovine clinical mastitis in Iran. Listeria spp. were detected in 21/207 bovine mastitic milk samples from dairy farms in Iran, comprising L. monocytogenes (n= 17), L. innocua (n= 3) and L. ivanovii (n= 1). L. monocytogenes isolates were grouped into serogroups '4b, 4d, 4e', '1/2a, 3a', '1/2b, 3b, 7' and '1/2c, 3c'; all harboured inlA, inlC and inlJ virulence genes. Listeria spp. were most frequently resistant to penicillin G (14/21 isolates, 66.7%) and tetracyclines (11/21 isolates, 52.4%). © 2013 Elsevier Ltd.

Atabani A.E.,University of Malaya | Atabani A.E.,University of Khartoum | Silitonga A.S.,University of Malaya | Badruddin I.A.,University of Malaya | And 3 more authors.
Renewable and Sustainable Energy Reviews | Year: 2012

As the fossil fuels are depleting day by day, there is a need to find out an alternative fuel to fulfill the energy demand of the world. Biodiesel is one of the best available resources that have come to the forefront recently. In this paper, a detailed review has been conducted to highlight different related aspects to biodiesel industry. These aspects include, biodiesel feedstocks, extraction and production methods, properties and qualities of biodiesel, problems and potential solutions of using vegetable oil, advantages and disadvantages of biodiesel, the economical viability and finally the future of biodiesel. The literature reviewed was selective and critical. Highly rated journals in scientific indexes were the preferred choice, although other non-indexed publications, such as Scientific Research and Essays or some internal reports from highly reputed organizations such as International Energy Agency (IEA), Energy Information Administration (EIA) and British Petroleum (BP) have also been cited. Based on the overview presented, it is clear that the search for beneficial biodiesel sources should focus on feedstocks that do not compete with food crops, do not lead to land-clearing and provide greenhouse-gas reductions. These feedstocks include non-edible oils such as Jatropha curcas and Calophyllum inophyllum, and more recently microalgae and genetically engineered plants such as poplar and switchgrass have emerged to be very promising feedstocks for biodiesel production. It has been found that feedstock alone represents more than 75% of the overall biodiesel production cost. Therefore, selecting the best feedstock is vital to ensure low production cost. It has also been found that the continuity in transesterification process is another choice to minimize the production cost. Biodiesel is currently not economically feasible, and more research and technological development are needed. Thus supporting policies are important to promote biodiesel research and make their prices competitive with other conventional sources of energy. Currently, biodiesel can be more effective if used as a complement to other energy sources. © 2012 Elsevier Ltd. All rights reserved.

Chekin F.,Islamic Azad University at Āmol | Bagheri S.,University of Malaya | Abd Hamid S.B.,University of Malaya
Sensors and Actuators, B: Chemical | Year: 2013

In this research, we reported a novel method for synthesis of Pt doped TiO2 nanoparticles (Pt-TiO2) by sol-gel assisted method. The synthesized Pt doped TiO2 nanoparticles were characterized using X-ray diffraction (XRD), transmission electronic microscopy (TEM) and FT-IR techniques. To investigate the catalytic efficiency of Pt-TiO2 nanoparticles, the electrooxidation of l-methionine (l-Met) using the deposited film of Pt doped TiO2 nanoparticles and carbon nanotubes composite on glassy carbon electrode (Pt-TiO2/CNT/GCE) was studied in buffer solution (pH 7.00) using cyclic voltammetry (CV). Bare GCE shows an ill-defined oxidation wave around 1.4 V for l-Met whereas Pt-TiO2/CNT/GCE shows a well-defined oxidation peak at 1.1 V. The modified electrode does not show any fouling effect toward the oxidation of l-Met. Amperometry method was used to determine l-Met in the concentration range of 0.5-100 μM with a detection limit of 0.1 μM (S/N = 3). The selectivity of the reaction has been assessed with no interference from tyrosine, lysine, cysteine, tryptophan, alanine and glutathione. The present modified electrode shows good recovery results for spiked l-Met in human blood serum sample. © 2012 Published by Elsevier B.V.

Siddiqui K.A.,University of Lucknow | Tiekink E.R.T.,University of Malaya
Chemical Communications | Year: 2013

Hydrogen bonding in the form of eight-membered {⋯HCNM}2 synthons is identified in the crystal structures of nickel and copper complexes. These C-H⋯M interactions lead to the formation of well-defined zero-, one- and even two-dimensional supramolecular aggregation patterns. © The Royal Society of Chemistry 2013.

Hamid Elsheikh M.,University of Malaya | Hamid Elsheikh M.,University of Khartoum | Shnawah D.A.,University of Malaya | Sabri M.F.M.,University of Malaya | And 4 more authors.
Renewable and Sustainable Energy Reviews | Year: 2014

Developing thermoelectric materials with superior performance means tailoring interrelated thermoelectric physical parameters - electrical conductivities, Seebeck coefficients, and thermal conductivities - for a crystalline system. High electrical conductivity, low thermal conductivity, and a high Seebeck coefficient are desirable for thermoelectric materials. Therefore, knowledge of the relation between electrical conductivity and thermal conductivity is essential to improve thermoelectric properties. In general, research in recent years has focused on developing thermoelectric structures and materials of high efficiency. The importance of this parameter is universally recognized; it is an established, ubiquitous, routinely used tool for material, device, equipment and process characterization both in the thermoelectric industry and in research. In this paper, basic knowledge of thermoelectric materials and an overview of parameters that affect the figure of merit ZT are provided. The prospects for the optimization of thermoelectric materials and their applications are also discussed. © 2013 Elsevier Ltd. All rights reserved.

Jamali H.,University of Malaya | Radmehr B.,Islamic Azad University at Karaj | Thong K.L.,University of Malaya
Food Control | Year: 2013

A total of 446 various raw milk samples were collected from numerous farm bulk milk tanks to examine the presence of Listeria species. These isolates were further characterised by biochemical tests and Polymerase Chain Reaction (PCR). Listeria spp. was isolated in 83 of the 446 samples (18.6%). The highest prevalence of Listeria spp. was detected in raw cow milk samples (22.5%), followed by raw sheep milk (16.4%) and raw goat milk (4.9%). The most common species isolated was Listeria innocua (57.8%); the remaining Listeria isolates were Listeria monocytogenes (21.7%), Listeria welshimeri (12%), and Listeria seeligeri (8.4%). Based on PCR serotyping, the 18 L.monocytogenes isolates were distributed into three serogroups "1/2a, 3a" (n=11), "1/2c, 3c" (n=5), and "4b, 4d, 4e" (n=2). All the examined L.monocytogenes were positive for internalin genes (inlA, inlC, and inlJ). The Listeria spp. isolates were resistant to tetracycline (49.4%) and penicillin G (43.4%) but remained susceptible to gentamicin, vancomycin and rifampicin. The findings of this study show that consumption of raw milk could be a potential risk of human listeriosis. © 2013 Elsevier Ltd.

Freeman M.A.,University of Malaya | Ogawa K.,University of Tokyo
International Journal for Parasitology | Year: 2010

Numerous global reports of the species Udonella caligorum, currently thought to be a species complex, suggests that the group may be species-rich. Herein we describe Udonella fugu n. sp., previously described as U. caligorum, found on the parasitic copepod Pseudocaligus fugu infecting Takifugu spp. from Japan. Using morphological data U. fugu can be distinguished from the current valid species by at least one of the traditionally used characters in udonellid taxonomy, and phylogenetic analyses of ssrDNA sequence data for U. fugu and other udonellids confirm that U. fugu forms a distinct clade from other udonellids including U. caligorum. Variable regions in the ssrDNA demonstrated a range of between 2.75 and 5.5% difference between currently recognized species of Udonella. These differences in ssrDNA sequences are phylogenetically useful when distinguishing between morphologically similar udonellids and can be used in conjunction with other data (morphology, phylogeography and fish host) to help clarify udonellid systematics. Udonella fugu was also found to cause significant damage to farmed tiger puffers through their feeding activities. Individual skin lesions were round in shape but merged with adjoining lesions to form more extensive lacerations. In some of the specimens from P. fugu infecting Takifugu niphobles, the protozoan ciliate Trichodina was found on the udonellid body surface and in their intestinal contents. We conclude that the udonellids are a more species-rich group than currently recognized, that early descriptions of new species may have been synonymized with U. caligorum in error and that the frequent global reports of U. caligorum may actually represent new species. This has led to a wide range of morphological descriptions for U. caligorum, blurring the usefulness of morphological data for the group. © 2009 Australian Society for Parasitology Inc.

Muthukumar P.,Gandhigram Rural Institute | Balasubramaniam P.,Gandhigram Rural Institute | Ratnavelu K.,University of Malaya
Chaos | Year: 2014

In this paper, we design a new three dimensional King Cobra face shaped fractional order chaotic system. The multi-scale synchronization scheme of two fractional order chaotic systems is described. The necessary conditions for the multi-scale synchronization of two identical fractional order King Cobra chaotic systems are derived through feedback control. A new cryptosystem is proposed for an image encryption and decryption by using synchronized fractional order King Cobra chaotic systems with the supports of multiple cryptographic assumptions. The security of the proposed cryptosystem is analyzed by the well known algebraic attacks. Numerical simulations are given to show the effectiveness of the proposed theoretical results. © 2014 AIP Publishing LLC.

Muthukumar P.,Gandhigram Rural Institute | Balasubramaniam P.,Gandhigram Rural Institute | Ratnavelu K.,University of Malaya
Nonlinear Dynamics | Year: 2014

In this paper, a new fractional order stretch-twist-fold (STF) flow dynamical system is proposed. The stability analysis of the proposed system equilibria is accomplished and we establish that the system is exhibited chaos even for order less than 3. The active control method is applied to enquire the hybrid phase synchronization between two identical fractional order STF flow chaotic systems. These synchronized systems are applied to formulate an authenticated encryption scheme newly for message (text and image) recovery. It is widely applied in the field of secure communication. Numerical simulations are presented to validate the effectiveness of the proposed theory. © 2014 Springer Science+Business Media Dordrecht.

Lee S.,Australian Institute for Plasma Focus Studies | Lee S.,INTI International University | Lee S.,University of Malaya
Journal of Fusion Energy | Year: 2014

The code couples the electrical circuit with plasma focus (PF) dynamics, thermodynamics and radiation. It is energy-, charge- and mass-consistent and accounts for the effects of transit times of small disturbances and plasma self-absorption. It has been used in design and interpretation of Mather-type PF experiments and as a complementary facility to provide diagnostic reference numbers in all gases. Information computed includes axial and radial dynamics, SXR emission characteristics and yield for various applications including microelectronics lithography and optimization of machines. Plasma focus neutron yield calculations, current and neutron yield limitations, deterioration of neutron scaling (neutron saturation), radiative collapse, speed-enhanced PF, current-stepped PF and extraction of diagnostic and anomalous resistance data from current signals have been studied using the code; which also produces reference numbers for fluence, flux and energy of deuteron beams and ion beams for all gases. There has been no pause in its continuous evolution in three decades so much so that the model code has no formal source reference except www.plasmafocus.net. This review presents, for the first time a comprehensive up-to-date version of the 5-phase model code. The equations of each phase are derived. Those of the first two phases are normalized to reveal important scaling parameters. The focus pinch phase is discussed with radiation-coupled dynamics necessitating the computation of radiation terms moderated by plasma self-absorption. Neutron and ion beam yields are computed. The 5-phase model code appears to be adequate for all Mather-type PF, lacking only in one aspect that for high inductance PF (termed Type 2) the measured current waveform contains an extended dip which cannot be fitted by the 5-phase code; necessitating an extended 6-phase code. This sixth phase (termed phase 4a) is dominated by anomalous resistance, providing a way to extract valuable data on anomalous resistivity from the current trace. © 2014 Springer Science+Business Media New York.

Ngeow W.C.,University of Malaya | Nair R.,American International Assurance Company
Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and Endodontology | Year: 2010

This article illustrates a case of persistent trigeminal neuralgia in a medically compromised 65-year-old female who did not respond to pharmacotherapy. She had undergone several peripheral neurectomies as well as a failed right posterior fossa exploration that resulted in a cerebrospinal fluid leak. Persistent pain over the right external nasal area and right mental region was relieved for several hours after daily injections of bupivacaine. A trial of a single dose of 100 units of botulinum toxin type A (BOTOX) diluted in 2.5 mL saline was injected into the external nasal trigger zone (60 units) and to the mental nerve region (40 units). She achieved complete pain relief in the external nasal region for 5 months. Pain recurred and the site was again injected with 100 units of botulinum toxin type A (BOTOX). Pain relief at the mental region was partial. This was finally controlled with peripheral neurectomy. The patient was pain free with a maintenance dose of 200 mg carbamazepine daily for about 1 year, after which she elected to undergo stereotactic gamma knife radiosurgery when pain recurred at the external nasal region. © 2010 Mosby, Inc. All rights reserved.

How G.T.S.,University of Malaya | Pandikumar A.,University of Malaya | Ming H.N.,University of Malaya | Ngee L.H.,University Putra Malaysia
Scientific Reports | Year: 2014

Titanium dioxide (TiO 2) with highly exposed {001} facets was synthesized through a facile solvo-thermal method and its surface was decorated by using reduced graphene oxide (rGO) sheets. The morphology and chemical composition of the prepared rGO/TiO 2 {001} nanocomposite were examined by using suitable characterization techniques. The rGO/TiO 2 {001} nanocomposite was used to modify glassy carbon electrode (GCE), which showed higher electrocatalytic activity towards the oxidation of dopamine (DA) and ascorbic acid (AA), when compared to unmodified GCE. The differential pulse voltammetric studies revealed good sensitivity and selectivity nature of the rGO/TiO 2 {001} nanocomposite modified GCE for the detection of DA in the presence of AA. The modified GCE exhibited a low electrochemical detection limit of 61/4M over the linear range of 2-601/4M. Overall, this work provides a simple platform for the development of GCE modified with rGO/TiO 2 {001} nanocomposite with highly exposed {001} facets for potential electrochemical sensing applications.

Lim C.S.,University of Malaya | Lim C.S.,Liverpool John Moores University | Rahim N.A.,University of Malaya | Hew W.P.,University of Malaya | Levi E.,Liverpool John Moores University
IEEE Transactions on Industrial Electronics | Year: 2013

Model predictive control (MPC) for a two-motor drive, supplied from a five-leg inverter, is presented in this paper. As an alternative to existing methods, use of MPC in multimachine drives has the advantages of independent fast current control of the machines, elimination of the closed-loop system's cascaded structure, and a reduced number of microcontrollers. A vector control algorithm is required, necessitating state-space modeling, with each machine's direct- and quadrature-axis currents chosen as state variables. Prediction of future states is via a discrete-time model of the five-leg inverter and a piecewise-affine model of two permanent-magnet synchronous motors (PMSMs). A method which eliminates unfeasible switching states inherent in reduced-switch-count inverters while reducing computation and sampling times is proposed. The algorithm is implemented in a TMS320F28335 DSP microcontroller, which controls the five-leg inverter and the two PMSMs. Simulation and experimental results validate the presented control concept. © 2012 IEEE.

Kupaei R.H.,University of Malaya | Alengaram U.J.,University of Malaya | Jumaat M.Z.B.,University of Malaya | Nikraz H.,Curtin University Australia
Construction and Building Materials | Year: 2013

This paper presents the experimental results of an on-going research project to produce geopolymer lightweight concrete using two locally available waste materials - low calcium fly ash (FA) and oil palm shell (OPS) - as the binder and lightweight coarse aggregate, respectively. A total of 32 mixes using different mixture proportions were prepared to get an appropriate mix design for fly ash based oil palm shell geopolymer lightweight concrete (OPSGPC). A mixture of sodium hydroxide and sodium silicate in different molarities was used as an alkali activator. The variables used in this investigation include the fly ash content, molarity and condition of OPS. The proposed mix design differs widely from the procedure used for mix proportioning of concrete produced with conventional lightweight and normal weight aggregates. The increase in FA content reduces the strength significantly due to additional water used for workability. The increase in molarity from 14 M to 16 M did not have desired effect on the compressive strength. However, the use of OPS with SSD condition produced higher strength than that of AD condition. The OPSGPC with 14 M, FA content of 480 kg/m3 and water to FA ratio of 0.34 produced 28-day compressive strength of about 32 MPa and is recommended for producing structural grade 30 OPSGPC. The demoulded densities of OPSGPC were within the limit of 2000 kg/m3 for lightweight concrete. © 2013 Elsevier Ltd. All rights reserved.

Huda A.S.N.,University of Malaya | Mekhilef S.,University of Malaya | Ahsan A.,University Putra Malaysia
Renewable and Sustainable Energy Reviews | Year: 2014

Bangladesh has been experiencing several problems over the past few decades. These include over population, energy crisis and global warming, etc. Adequate amount of power generation in a sustainable way is an important issue for rapidly increasing population and economic development. Renewable energy can play an effective role to meet energy demand. Since it is an agrarian country, biomass is one of the potential renewable energy sources in Bangladesh. Agricultural crop residues, animal manure and municipal solid waste are the major sources of biomass energy in the country. This paper presents the scope, potential and technologies related to the use of biomass resources. The study also discusses the biomass projects undertaken by the government and non-government organizations, plans and strategies to promote biomass technologies in Bangladesh. © 2013 Elsevier Ltd. All rights reserved.

Lee H.V.,University of Malaya | Juan J.C.,University of Malaya | Taufiq-Yap Y.H.,University Putra Malaysia
Renewable Energy | Year: 2015

A simple method was developed for biodiesel production from non-edible Jatropha oil which contains high free fatty acid using a bifunctional acid-base catalyst. The acid-base catalyst comprising CaO and La2O3 mixed metal oxides with various Ca/La atomic ratios were synthesized via co-precipitation method. The effects of Ca/La compositions on the surface area, acidity-basicity and transesterification activity were investigated. Integrated metal-metal oxide between Ca and La enhanced the catalytic activity due to well dispersion of CaO on composite surface and thus, increased the surface acidic and basic sites as compared to that of bulk CaO and La2O3 metal oxide. Furthermore, the transesterification reactions resulted that the catalytic activity of CaO-La2O3 series were increased with Ca/La atomic ratio to 8.0, but the stability of binary system decreased by highly saturated of CaO on the catalyst surface at Ca/La atomic ratio of 10.0. The highest biodiesel yield (98.76%) was achieved under transesterification condition of 160°C, 3h, 25 methanol/oil molar ratio and 3wt.%. In addition, the stability of CaO-La2O3 binary system was studied. In this study, Ca-La binary system is stable even after four cycles with negligible leaching of Ca2+ ion in the reaction medium. © 2014 Elsevier Ltd.

Sani Y.M.,University of Malaya | Sani Y.M.,Ahmadu Bello University | Daud W.M.A.W.,University of Malaya | Abdul Aziz A.R.,University of Malaya
Applied Catalysis A: General | Year: 2014

Homogeneous acid catalysts received wide acceptability because of their fast reaction rates. However, postproduction costs incurred from aqueous quenching, wastewater and loss of catalysts led to the search for alternatives. Until recently, heterogeneous base catalyzed-biodiesel production also gained the attention of most researchers. This was because the process minimized the problems of homogeneous catalysis in terms of catalyst regeneration and recycling in continuous processes. However, despite these advances, the ultimate aim of producing biodiesel at affordable cost is yet to be realized. Further, the process requires refined feedstocks which account for as high as 88% of the final production costs. Thus, the focus of many research efforts is towards the rational design and development of solid acid catalysts aimed at reducing biodiesel production costs. Therefore, this study reviewed current literature on the activities and advantages of solid acid catalysts used in biodiesel production. It discussed in details how the preparation method and prevailing reaction conditions affect the catalytic activity of the catalyst. The review concluded by suggesting way forward from the traditional trial-and-error method to a rational means of determining catalytic activities. © 2013 Elsevier Ltd. All rights reserved.

Sun Z.,Curtin University Australia | Ng K.-H.,University of Malaya
European Journal of Radiology | Year: 2012

Purpose: To perform a systematic review of the radiation dose and diagnostic accuracy of prospective versus retrospective ECG-gated multislice CT coronary angiography. Materials and methods: A search of Pubmed/Medline and Sciencedirect databases for English literature was performed to identify studies comparing prospective and retrospective ECG-gated multislice CT angiography in the diagnosis of coronary artery disease. Effective dose, dose length product, image quality and diagnostic value were compared between two groups of studies. Results: 22 studies were included for analysis. The mean effective dose of prospective ECG-gated scans was 4.5 mSv (95% CI: 3.6, 5.3 mSv), which is significantly lower than that of retrospective scans, which is 13.8 mSv (95% CI: 11.5, 16.0 mSv) (p < 0.001). The mean dose length product was 225 mGy cm (95% CI: 188, 262 mGy cm) and 822 mGy cm (95% CI: 630, 1013 mGy cm) for the prospective and retrospective ECG-gated scans, respectively, indicating a statistically significant difference between these two protocols (p < 0.0001). The mean sensitivity and specificity of multislice CT angiography in the diagnosis of coronary artery disease was 97.7% (95% CI: 93.7%, 100%) and 92.1% (95% CI: 87.2%, 97%) for prospective ECG-gated scans; 95.2% (95% CI: 91%, 99.5%) and 94.4% (95% CI: 88.5%, 100%) for retrospective ECG-gated scans, respectively, with no significant difference for sensitivity but significant difference for specificity (p = 0.047). Conclusion: Multislice CT coronary angiography with prospective ECG-gating leads to a significant reduction of radiation dose when compared to that of retrospective ECG-gating, while offering comparable image quality and diagnostic value. © 2011 Elsevier Ireland Ltd. All rights reserved.

Lim C.S.,University of Malaya | Lim C.S.,Liverpool John Moores University | Levi E.,Liverpool John Moores University | Jones M.,Liverpool John Moores University | And 2 more authors.
IEEE Transactions on Industrial Electronics | Year: 2014

This paper presents an investigation of the finite-control-set model predictive control (FCS-MPC) of a five-phase induction motor drive. Specifically, performance with regard to different selections of inverter switching states is investigated. The motor is operated under rotor flux orientation, and both flux/torque producing (d-q) and nonflux/torque producing (x-y) currents are included into the quadratic cost function. The performance is evaluated on the basis of the primary plane, secondary plane, and phase (average) current ripples, across the full inverter's linear operating region under constant flux-torque operation. A secondary plane current ripple weighting factor is added in the cost function, and its impact on all the studied schemes is evaluated. Guidelines for the best switching state set and weighting factor selections are thus established. All the considerations are accompanied with both simulation and experimental results, which are further compared with the steady-state and transient performance of a proportional-integral pulsewidth modulation (PI-PWM)-based current control scheme. While a better transient performance is obtained with FCS-MPC, steady-state performance is always superior with PI-PWM control. It is argued that this is inevitable in multiphase drives in general, due to the existence of nonflux/torque producing current components. © 1982-2012 IEEE.

Kristmundsson A.,University of Iceland | Freeman M.A.,University of Malaya
Parasites and Vectors | Year: 2013

Background: Approximately 40 species of Sphaeromyxa have been described, all of which are coelozoic parasites from gall bladders of marine fish. They are unique amongst the myxosporeans as they have polar filaments that are flat and folded instead of being tubular and spirally wound. This unusual feature was used as a subordinal character to erect the suborder Sphaeromyxina, which contains one family, the Sphaeromyxidae, and a single genus Sphaeromyxa. Methods. In the present study, we examine eelpout from the genus Lycodes from Iceland for the presence of myxosporean parasites in the gall bladder and perform morphological and DNA studies. Results: A novel myxosporean, Sphaeromyxa lycodi n. sp., was identified in the gall bladders of five of the six species of Lycodes examined, with a prevalence ranging from 29 - 100%. The coelozoic plasmodia are large, polysporous and contain disporic pansporoblasts and mature spores which are arcuate. The pyriform polar capsules encase long and irregularly folded ribbon-like polar filaments. Each spore valve has two distinct ends and an almost 180°twist along the relatively indistinct suture line. The single sporoplasm is granular with two nuclei. Sphaeromyxa lycodi is phylogenetically related to other arcuate sphaeromyxids and is reproducibly placed with all known sphaeromyxids and forms part of a robustly supported clade of numerous myxosporean genera which infect the hepatic biliary systems of a wide range of hosts. Conclusions: Sphaeromyxa lycodi is a common gall bladder myxosporean in eelpout of the genus Lycodes from Northern Iceland. It has characteristics typical of the genus and develops arcuate spores. Molecular phylogenetic analyses confirm that sphaeromyxids form a monophyletic group, subdivided into straight and arcuate spore forms, within the hepatic biliary clade that infect a wide range of freshwater associated animals. The ancestral spore form for the hepatic biliary clade was probably a Chloromyxum morphotype; however, sphaeromyxids have more recently evolved from an ancestor with a spindle-shaped Myxidium spore form. We recommend that the suborder Sphaeromyxina is suppressed; however, we retain the family Sphaeromyxidae and place it in the suborder Variisporina. © 2013 Kristmundsson and Freeman; licensee BioMed Central Ltd.

Lee H.V.,University of Malaya | Taufiq-Yap Y.H.,University Putra Malaysia
Process Safety and Environmental Protection | Year: 2015

The focus of this study is to produce biodiesel using non-edible feedstock (Jatropha curcas oil) via heterogeneous base catalyzed transesterification reaction. The solid base catalysts, binary metal oxide (CaO-ZnO and CaO-La2O3) were selected for the transesterification of high acid jatropha oil. Furthermore, the design of experiments was performed using 5-level-4 factor central composite design coupled with response surface methodology (RSM) in order to optimize the transesterification conditions. Four process factors were evaluated: (1) reaction time (1-5 h), (2) methanol/oil molar ratio (15:1-30:1), (3) reaction temperature (40-200 °C) and (4) catalyst loading (1-5 wt.%). Based on the quadratic model generated from RSM, reaction temperature rendered the most significant effect for both CaO-ZnO and CaO-La2O3 catalyzed reactions, followed by catalyst loading and reaction time. Besides, both reaction models showed that interaction between reaction temperature with reaction time and catalyst loading has positively influenced the biodiesel yield. The highest conversion predicted for CaO-ZnO and CaO-La2O3 catalyzed reactions was 97.03% and 96.27%, respectively, with reasonable predictability and sufficient accuracy data (small error: 0.33-0.34%). Furthermore, the physicochemical characteristics of produced biodiesel were tested with compliance to ASTM D7851 and EN 14124. © 2014 The Institution of Chemical Engineers.

Sun Z.,Curtin University Australia | Choo G.H.,Sime Darby Medical Center | Ng K.-H.,University of Malaya
British Journal of Radiology | Year: 2012

Coronary CT angiography has been increasingly used in the diagnosis of coronary artery disease owing to rapid technological developments, which are reflected in the improved spatial and temporal resolution of the images. High diagnostic accuracy has been achieved with multislice CT scanners (64 slice and higher), and in selected patients coronary CT angiography is regarded as a reliable alternative to invasive coronary angiography. With high-quality coronary CT imaging increasingly being performed, patients can benefit from an imaging modality that provides a rapid and accurate diagnosis while avoiding an invasive procedure. Despite the tremendous contributions of coronary CT angiography to cardiac imaging, study results reported in the literature should be interpreted with caution as there are some limitations existing within the study design or related to patient risk factors. In addition, some attention must be given to the potential health risks associated with the ionising radiation received during cardiac CT examinations. Radiation dose associated with coronary CT angiography has raised serious concerns in the literature, as the risk of developing malignancy is not negligible. Various dose-saving strategies have been implemented, with some of the strategies resulting in significant dose reduction. The aim of this review is to present an overview of the role of coronary CT angiography on cardiac imaging, with focus on coronary artery disease in terms of the diagnostic and prognostic value of coronary CT angiography. Various approaches for dose reduction commonly recommended in the literature are discussed. Limitations of coronary CT angiography are identified. Finally, future directions and challenges with the use of coronary CT angiography are highlighted. © 2012 The British Institute of Radiology.

Taha Z.,Universiti Malaysia Pahang | Rostam S.,University of Malaya
International Journal of Advanced Manufacturing Technology | Year: 2011

In respond to new market requirements and competitive positioning of manufacturing companies and in order to provide cost effective, high performance products, there is a need for reconfigurable manufacturing systems with a view of introducing new manufacturing technologies. However one of the problems faced is how to select the alternative machines that are consistent with manufacturing goals. In this paper a decision support system is presented for machine tool selection in flexible manufacturing cell using fuzzy analytic hierarchy process (fuzzy AHP) and artificial neural network. A program is developed in the model to find the Priority weights of the Evaluation Criteria and Alternative's Ranking called PECAR for fuzzy AHP model. The artificial neural network (ANN) is used to verify the results of fuzzy AHP (PECAR program) and to predict the alternatives' ranking. A feed forward back propagation ANN is designed and trained using the results from the program. A numerical example to select the most suitable CNC machine based on data collected from a designed questionnaire is given to demonstrate the applicability of the proposed model. The result of neural net simulation is compared with the results from fuzzy AHP model. It is concluded that the proposed decision support system by combining the fuzzy AHP and ANN models can be used as a powerful tool to select the most suitable alternative machines to form the structure of a flexible manufacturing cell. © 2011 Springer-Verlag London Limited.

Freeman M.A.,University of Malaya | Kasper J.M.,Iceland Marine Research Institute | Kristmundsson A.,University of Iceland
Parasites and Vectors | Year: 2013

Background: Commercial fisheries of lumpfish Cyclopterus lumpus have been carried out in Iceland for centuries. Traditionally the most valuable part is the eggs which are harvested for use as a caviar substitute. Previously reported parasitic infections from lumpfish include an undescribed intranuclear microsporidian associated with abnormal kidneys and mortalities in captive lumpfish in Canada. During Icelandic lumpfish fisheries in spring 2011, extensive enlargements to the kidneys were observed in some fish during processing. The aim of this study was to identify the pathogen responsible for these abnormalities. Methods. Lumpfish from the Icelandic coast were examined for the causative agent of kidney enlargement. Fish were dissected and used in histological and molecular studies. Results: Lumpfish, with various grades of clinical signs, were observed at 12 of the 43 sites sampled around Iceland. From a total of 77 fish examined, 18 had clear clinical signs, the most prominent of which was an extensive enlargement and pallor of the kidneys. The histopathology of the most severely affected fish consisted of extensive degeneration and necrosis of kidney tubules and vacuolar degeneration of the haematopoietic tissue. Intranuclear microsporidians were detected in all organs examined in fish with prominent clinical signs and most organs of apparently healthy fish using the new PCR and histological examination. One or multiple uniformly oval shaped spores measuring 3.12 ± 0.15 × 1.30 ± 0.12 μm were observed in the nucleus of affected lymphocytes and lymphocyte precursor cells. DNA sequencing provided a ribosomal DNA sequence that was strongly supported in phylogenetic analyses in a clade containing other microsporidian parasites from the Enterocytozoonidae, showing highest similarity to the intranuclear microsporidian Nucleospora salmonis. Conclusions: Intranuclear microsporidian infections are common in wild caught lumpfish from around the Icelandic coast. Infections can cause severe clinical signs and extensive histopathological changes, but are also present, at lower levels, in fish that do not show clinical signs. Some common features exist with the intranuclear microsporidian previously reported from captive Canadian lumpfish, but DNA sequence data is required from Canadian fish to confirm conspecificity. Based on phylogenetic analysis and the intranuclear location of the parasite, the name Nucleospora cyclopteri n. sp. is proposed. © 2013 Freeman et al; licensee BioMed Central Ltd.

Lim S.P.,University of Malaya | Huang N.M.,University of Malaya | Lim H.N.,University Putra Malaysia
Ceramics International | Year: 2013

A facile solvent-based synthesis route based on the oxidation-reduction reaction between graphene oxide (GO) and SnCl2·2H2O has been developed to synthesize SnO2/graphene (SnO2/G) nanocomposites. The reduction of GO and the in situ formation of SnO2 nanoparticles were achieved in one step. Characterization by X-ray diffraction (XRD), ultraviolet-visible (UV-vis) absorption spectroscopy, Raman spectroscopy, and field emission scanning electron microscopy (FESEM) confirmed the feasibility of using the solvothermally treated reaction system to simultaneously reduce GO and form SnO2 nanoparticles with an average particle size of 10 nm. The electrochemical performance of SnO 2/graphene showed an excellent specific capacitance of 363.3 F/g, which was five-fold higher than that of the as-synthesized graphene (68.4 F/g). The contributing factors were the synergistic effects of the excellent conductivity of graphene and the nanosized SnO2 particles. © 2013 Elsevier Ltd and Techna Group S.r.l.

Samsudin N.I.P.,University Putra Malaysia | Abdullah N.,University of Malaya
Mycotoxin Research | Year: 2013

Red rice is a fermented product of Monascus spp. It is widely consumed by Malaysian Chinese who believe in its pharmacological properties. The traditional method of red rice preparation disregards safety regulation and renders red rice susceptible to fungal infestation and mycotoxin contamination. A preliminary study was undertaken aiming to determine the occurrence of mycotoxigenic fungi and mycotoxins contamination on red rice at consumer level in Selangor, Malaysia. Fifty red rice samples were obtained and subjected to fungal isolation, enumeration, and identification. Citrinin, aflatoxin, and ochratoxin-A were quantitated by ELISA based on the presence of predominant causal fungi. Fungal loads of 1.4×104 to 2.1×10 6 CFU/g exceeded Malaysian limits. Monascus spp. as starter fungi were present in 50 samples (100%), followed by Penicillium chrysogenum (62%), Aspergillus niger (54%), and Aspergillus flavus (44%). Citrinin was present in 100% samples (0.23-20.65 mg/kg), aflatoxin in 92% samples (0.61-77.33 μg/kg) and Ochratoxin-A in 100% samples (0.23-2.48 μg/kg); 100% citrinin and 76.09% aflatoxin exceeded Malaysian limits. The presence of mycotoxigenic fungi served as an indicator of mycotoxins contamination and might imply improper production, handling, transportation, and storage of red rice. Further confirmatory analysis (e.g., HPLC) is required to verify the mycotoxins level in red rice samples and to validate the safety status of red rice. © Society for Mycotoxin Research and Springer-Verlag 2012.

Miao J.,University of Science and Technology Beijing | Hooi Chew K.,University of Malaya | Jiang Y.,University of Science and Technology Beijing
Applied Physics Letters | Year: 2011

(Ba 0.8Sr 0.2)(Zr 0.2Ti 0.8)O 3 (BSZT) films were grown on La 0.5Sr 0.5CoO 3 buffered (001) SrTiO 3 substrates by pulsed laser deposition. Effects of Co doping on electrical properties of the films were investigated to establish material design through defects control. The doping led to a significant improvement in the electrical properties with reduction in leakage current and dielectric loss. In addition, the dielectric tunability and figure of merit were enhanced, implying that Co-doped BSZT films are promising materials for tunable microware applications. Our detail studies suggest that the improved electrical properties of Co-doped BSZT films are closely related to defect concentrations in the films. © 2011 American Institute of Physics.

Sun Z.,Curtin University Australia | Ng K.-H.,University of Malaya
International Journal of Cardiovascular Imaging | Year: 2012

To perform a systematic review and metaanalysis of the diagnostic value of prospective ECGgating coronary CT angiography in the diagnosis of coronary artery disease. A search of biomedical databases for English literature was performed to identify studies investigating the diagnostic value of 64- or more slice CT angiography with use of prospective ECG-gating in the diagnosis of coronary artery disease. Sensitivity, specificity, positive and negative predictive value estimates pooled across studies were tested using a fixed effects model. Fourteen studies met selection criteria for inclusion in the analysis. Pooled estimates and 95% confidence interval (CI) of sensitivity, specificity, positive and negative predictive value of prospective ECG-gating coronary CT angiography for diagnosis of significant coronary stenosis were 99% (95% CI: 98, 100%), 91% (95% CI: 88, 94%), 94% (95% CI: 91, 96%) and 99% (95% CI: 97, 100%), according to the patient-based assessment. The mean values of sensitivity, specificity, positive and negative predictive value of prospective ECG-gating coronary CT angiography were 95% (95% CI: 93, 96%), 95% (95% CI: 93, 95%), 88% (95% CI: 86, 90%), and 98% (95% CI: 97, 98%), according to vessel-based assessment; 92% (95% CI: 90, 93%), 97% (95% CI: 97, 98%), 84% (95% CI: 82, 86%), 99% (95% CI: 99, 99%), according to segmentbased assessment, respectively. The mean effective dose was 3.3 mSv (95% CI: 2.3, 4.1 mSv) for the prospective ECG-gating coronary CT angiography. This analysis shows that for a predominantly male population with a high disease prevalence the use of coronary CT angiography with prospective ECG gating allows for a reduced radiation exposure without a sacrifice in diagnostic efficacy. © Springer Science+Business Media, B.V. 2012.

Lim H.N.,University of Malaya | Huang N.M.,University of Malaya | Loo C.H.,University Putra Malaysia
Journal of Non-Crystalline Solids | Year: 2012

Chitosan is considered a model polymer because of its excellent biocompatibility, biodegradability, antibacterial property and metal binding ability. Despite the favorable properties, the poor mechanical strength and the loss of structural integrity limits the applications of chitosan. Graphene's intrinsic low weight with excellent thermal stability makes it an ideal filler for reinforcing polymers. In this work, we prepared graphene oxide (GO) via Hummer's method and simplified Hummer's method using graphite powder and graphite flakes as starting materials, respectively. The GO obtained using Hummer's method and simplified Hummer's method had a small area of less than 50 μm 2 and a large area of about 7000 μm 2, respectively. The small area GO and large area GO were reduced by sodium hydroxide, in which the reduced GO (rGO) with small area and large area were incorporated into a chitosan matrix, respectively, using a simplistic drop-casting technique to produce a thin film. Glass transition temperature (T g) and mechanical strength of chitosan/large area rGO at concentrations of 0.3, 0.6 and 0.9 wt.% of GO were found to be better than chitosan/small area rGO. We also investigated the T g and mechanical strength between chitosan/small area GO and chitosan/small area rGO, where we discovered that the former had better thermal and tensile properties. By comparing the T g and mechanical strength of chitosan/small area GO against chitosan/large area GO, we found that the latter displayed superior thermal and tensile properties. Antibacterial tests were performed on the graphene-based chitosan composites and their ability to act as bactericide was manifested in the retardation of the growth of Pseudomonas aeruginosa. These composite materials with excellent thermal, tensile and antimicrobial properties find real-life applications in the physical, chemical, mechanical, electrical and bioengineering fields. © 2011 Elsevier B.V. All rights reserved.

Taha Z.,Universiti Malaysia Pahang | Rostam S.,University of Malaya
Journal of Intelligent Manufacturing | Year: 2012

The selection process of a suitable machine tool among the increased number of alternatives has been an important issue for manufacturing companies for years. This is because the improper selection of a machine tool may cause many problems that will affect the overall performance. In this paper, a decision support system (DSS) is presented to select the best alternative machine using a hybrid approach of fuzzy analytic hierarchy process (fuzzy AHP) and preference ranking organization method for enrichment evaluation (PROMETHEE). A MATLAB- based fuzzy AHP is used to determine the weights of the criteria and it is called program for PriorityWeights of the Evaluation Criteria (PWEC), and the PROMETHEE method is applied for the final ranking. The proposed model is structured to select the most suitable computer numerical controlled (CNC) turning centre machine for a flexible manufacturing cell (FMC) among the alternatives which are assigned from a database (DB) created for this purpose. A numerical example is presented to show the applicability of the model. It is concluded that the proposed model has the capability of dealing with a wide range of desired criteria and to select any type of machine tool required for building an FMC. © Springer Science+Business Media, LLC 2011.

Omar R.,University Technical Malaysia Melaka | Rahim N.A.,University of Malaya
International Journal of Electrical Power and Energy Systems | Year: 2012

This paper presents the analysis and design of a three phase four wire Dynamic Voltage Restorer (DVR) based on supercapacitor as energy storage for power quality improvement in electrical distribution system. The proposed system comprises of a supercapacitor as energy storage, DC-DC converter, and the power circuit of the DVR. It involves the construction of the proposed DVR topologies consists of filtering scheme, isolation or distribution transformer, injection transformer and Voltage Source Inverter (VSI). The main aims of this paper covers design, modeling, construction and testing of a laboratory DVR prototype for a three phase four wire system. This system is capable to mitigate voltage disturbances at low voltage distribution system. The implementation of supercapacitor as an energy storage is to supply real power to the inverter during disturbances. The experimental results of the prototype were also illustrated. The controllers based on d-q-0 transformation technique and Proportional Integral (PI) was applied to the DVR. The proposed controller was then coded into a digital signal processor (DSP) TMS320F2812 board. The proposed system is verified through simulation and is implemented in a prototype, and the experimental results are compared. © 2012 Elsevier Ltd. All rights reserved.

Lee Y.K.,University of Malaya | Lee P.Y.,University Putra Malaysia | Ng C.J.,University of Malaya
BMC Family Practice | Year: 2012

Background: Nationwide surveys have shown that the prevalence of diabetes rates in Malaysia have almost doubled in the past ten years; yet diabetes control remains poor and insulin therapy is underutilized. This study aimed to explore healthcare professionals views on barriers to starting insulin therapy in people with type 2 diabetes. Methods: Healthcare professionals consisting of general practitioners (n = 11), family medicine specialists (n = 10), medical officers (n = 8), government policy makers (n = 4), diabetes educators (n = 3) and endocrinologists (n = 2) were interviewed. A semi-structured topic guide was used to guide the interviews by trained facilitators. The interviews were transcribed verbatim and analysed using a thematic analysis approach. Results: Insulin initiation was found to be affected by patient, healthcare professional and system factors. Patients barriers include culture-specific barriers such as the religious purity of insulin, preferred use of complementary medication and perceived lethality of insulin therapy. Healthcare professionals barriers include negative attitudes towards insulin therapy and the legacy effect of old insulin guidelines; whilst system barriers highlight the lack of resources, language and communication challenges. Conclusions: Tackling the issue of insulin initiation should not only happen during clinical consultations. It requires health education to emphasise the progressive nature of diabetes and the eventuality of insulin therapy at early stage of the illness. Healthcare professionals should be trained how to initiate insulin and communicate effectively with patients from various cultural and religious backgrounds.© 2012 Lee et al.

Naganathan S.,University of Tenaga Nasional | Razak H.A.,University of Malaya | Hamid S.N.A.,Kualiti Alam Sdn Bhd
Materials and Design | Year: 2012

Industrial waste incineration bottom ash and quarry dust are waste materials which, if reused, will contribute to sustainability. One of the potential uses of these materials in bulk quantities is in controlled low-strength material (CLSM). This paper evaluates the properties of controlled low-strength material (CLSM) made using industrial waste incineration bottom ash and quarry dust. Various mix proportions of CLSM containing bottom ash and quarry dust were developed and the properties evaluated. Tests were performed on the CLSM in fresh and hardened states involving flowability, stability, setting time, segregation resistance, California bearing ratio (CBR), and corrosivity and the results discussed. Results indicated that the setting time of the CLSM mixtures tested ranged from 3.7 to 8h, the fresh density from 1539 to 2100kg/m3, strength values from 0.22 to 11.42MPa, mixtures were stable and no corrosivity. It is shown that addition of quarry dust enhanced the performance of CLSM made using bottom ash with regard to stability, strength, and CBR and hence both the industrial waste incineration bottom ash and quarry dust are potential materials for use in CLSM. © 2011 Elsevier Ltd.

Wong S.-M.,University of Malaya | Baba R.,Hospital Kuala Lumpur
International Journal of Dermatology | Year: 2012

Background Vitiligo is a chronic disease and can have significant impairment on patients' quality of life (QoL). Studies have shown that limitations in QoL are similar in magnitude to patients with other chronic skin diseases like psoriasis. The objective of this study was to assess the quality of life (QoL) of patients with vitiligo attending the dermatology clinic of a tertiary hospital in Malaysia. Methods All patients with a clinical diagnosis of vitiligo who were seen at our dermatology clinic and phototherapy daycare center from September 15 to November 20, 2009 were invited to participate. Results A total of 102 patients with vitiligo were included in this survey (56.9% females, 43.1% males; mean age 43.6). The mean DLQI score±SD was 6.40±5.17. The highest mean DLQI score was seen in the patient group aged 30-59 years (mean score 7.05). Malays had significantly higher DLQI scores compared with Indians (P=0.026). Conclusion Patients in our cohort showed a moderate limitation of QoL, comparable to that of other chronic skin diseases. Management should focus not only on medical treatment but also psychological aspects, hence better QoL and treatment outcomes. © 2012 The International Society of Dermatology.

Ullah K.R.,University of Malaya | Saidur R.,University of Malaya | Ping H.W.,University of Malaya | Akikur R.K.,University of Malaya | Shuvo N.H.,Arizona State University
Renewable and Sustainable Energy Reviews | Year: 2013

Energy is the lifeblood of the modern world. Because of the negative environmental impacts and limited sources of fossil fuels, researchers are increasingly focusing on renewable energy sources, particularly solar energy due to its cleanliness and natural availability. Along with photovoltaic systems, solar thermal energy has been used over the last few decades to meet the refrigeration needs for both domestic and industrial purposes. This study presents a review of different solar thermal refrigeration systems, with a specific focus on solar absorption refrigeration systems and solar adsorption refrigeration systems within various working fluids. The different working pairs are illustrated by considering their coefficients of performance, specific cooling power, cooling capacity and minimum and maximum working temperatures. By considering cooling efficiency and other problems, such as swelling and agglomeration, the study also explores solar thermal hybrid cooling systems with heterogeneous composite pairs. © 2013 Elsevier Ltd. All rights reserved.

Pirasteh G.,University of Malaya | Saidur R.,University of Malaya | Rahman S.M.A.,University of Sharjah | Rahim N.A.,University of Malaya
Renewable and Sustainable Energy Reviews | Year: 2014

Drying is an essential process in the preservation of agricultural crops and in industries, such as textile production, dairy processing, cement production, clay brick production, tile production, wood and timber processing, wastewater treatment, and biomass treatment. The energy requirement for drying can be supplied from various sources, namely, electricity, fossil fuel, natural gas, wood, bark forest residual, and solar. Although the use of solar radiation for drying has existed since antiquity, it has not yet been widely commercialized, particularly in the industrial sector. Considering the rapid depletion of natural fuel resources and because of the rising fossil fuel cost, solar drying is expected to become indispensable in the future. Moreover, environmental considerations and damages caused by human beings due to increasing consumption of fossil fuel prompt governments and industries to use renewable energies as a clean and sustainable resource, thus, the use of solar energy for drying. The numerous solar drying applications are classified into two main categories, that is, agricultural and industrial. Many benefits could be exploited from solar energy for drying applications. Solar energy enables the industries and agricultural sectors to modify their energy requirement, improve their energy stability, and increase energy sustainability, which lead to improvement in the system efficiency. We review the role of the drying system in industry and agriculture, the energy consumption capacity, and the availability of the required energy for the products to be dried. In addition, the economical, environmental, and political aspects of using solar dryers are discussed. Special attention is given to industrial drying and in finding opportunities to use compatible dryers for a certain industry. In short, we conduct a comprehensive review of the new approach to use solar energy in industrial drying sector. © 2013 Elsevier Ltd. All rights reserved.

Mekhilef S.,University of Malaya | Abdul Kadir M.N.,University of Malaya | Salam Z.,University of Technology Malaysia
IEEE Transactions on Industrial Informatics | Year: 2013

Three-stage 18-level hybrid inverter design with novel control method is presented. The inverter consists of main high-, medium-, and low-voltage stages connected in series from the output side. The high-voltage stage is a three-phase, six-switch conventional subinverter. The medium- and low-voltage stages are made of three-level subinverters constructed by H-bridge units. The proposed control strategy assumes a reference input voltage vector and aims to approximate it to the nearest inverter vector. The control concept is based on holding the high-voltage state as long as it is feasible to do so. The reference voltage vector has been represented in a 60°-spaced two axis coordinate system to reduce the computational effort. The concept of the staged-control has been presented, the transformed inverter vectors and their relation to the switching variables have been defined, and the implementation process has been described. The test results verify the effectiveness of the proposed strategy in terms of computational efficiency as well as the capability of the inverter to produce very low distorted voltage with low switching losses. © 2012 IEEE.

Mohammed Y.S.,University of Technology Malaysia | Mokhtar A.S.,University of Technology Malaysia | Bashir N.,University of Technology Malaysia | Saidur R.,University of Malaya
Renewable and Sustainable Energy Reviews | Year: 2013

Efforts to improve the quality of life in rural areas rely upon the provision of electrical energy services. Globally, the focus is on identifying and maintaining sustainable and environmentally friendly energy resources, by means of the clean development mechanism (CDM). Supplying electricity by extending the grid to rural domains is, in most cases, economically unproductive, taking into account other related factors that pertain, especially in developing countries. Furthermore, an unfolding energy crisis in the sub-Saharan Africa (SSA) region intensifies the need for decentralized bioenergy applications using modern conversion techniques. Biomass energy produced in rural areas provides a sustainable alternative to grid electricity. This paper presents an overview of the potential of agricultural biomass-based resources for decentralized energy in rural areas of Ghana. It emphasizes the strategic importance of biomass energy, especially in areas where it is economically attractive because of the ready availability of resources. Assimilation of past and current research reported in the literature on biomass resources and bioenergy technologies in the country underpins this study. A more detailed evaluation of agricultural biomass-based potential was carried out and 2010 was chosen as the base period for the assessment. The result suggests that Ghana has a suitable potential of bioenergy resources and this holds considerable promise for future energy delivery in the country. The paper concludes with discussion of various promising decentralized bioenergy technologies for the exploitation of resources in Ghana. © 2012 Elsevier Ltd.

Mekhilef S.,University of Malaya | Faramarzi S.Z.,University of Malaya | Saidur R.,University of Malaya | Salam Z.,University of Technology Malaysia
Renewable and Sustainable Energy Reviews | Year: 2013

Solar energy is one of the cleanest sources of alternative energy. Due to high energy demand in one hand and environmental negative impact of fossil fuels, on the other hand, many countries consider the alternative energy sources as a suitable and feasible option in industry and domestic usage. It was discovered that the different applications of solar energy in industries are being accepted more than ever. The present study is a state of art on the numerous new and feasible technologies of solar energy applications in the agricultural sectors. It discusses about the importance of solar energy as environmental clean technologies and the most reliable energy source. This study covers different types of solar energy systems like as solar photovoltaic and solar thermal for pumping water, drying crops, cooling the storages and producing heating/cooling greenhouses. It has been proven that photovoltaic systems and/or solar thermal system would be the suitable options in agricultural application and especially for the distant rural area. © 2012 Elsevier Ltd.

Soltanian M.R.K.,University of Malaya | Sadegh Amiri I.,University of Malaya | Alavi S.E.,University of Technology Malaysia | Ahmad H.,University of Malaya
Journal of Lightwave Technology | Year: 2015

We demonstrate a widely tunable dual-wavelength erbium-doped fiber laser that used a 10-cm photonic crystal fiber as a Mach-Zehnder interferometer to filter out the switchable dual-wavelength signals so as to generate tunable continuous-wave (CW) terahertz (THz) radiation. Each single longitudinal mode wavelength could be independently tuned by using a tunable band-pass filter and polarization controller (PC). The wavelength fine-tuning was achieved via adjustments to the PC, and the resulting dual-wavelength output had a side-mode suppression ratio (SMSR) of more than 30 dB. The wavelength spacing of 7, 11.4, and 21.2 nm, corresponding to 0.9, 1.4, and 2.66 THz radiation, respectively, was tuned in order to obtain CW THz radiation. This CW THz radiation was produced by means of a stable dual-wavelength fiber laser performing as the optical beat source, together with a DAST crystal-based photomixer. High-sensitivity thermal sensors calibrated for THz radiation were able to continuously detect the emitted CW THz radiation. © 1983-2012 IEEE.

Vanaki S.,University of Malaya | Mohammed H.A.,University of Technology Malaysia
International Communications in Heat and Mass Transfer | Year: 2015

A numerical investigation is performed to study the effects of different rib shapes and turbulent nanofluid flow on the thermal and flow fields through transversely roughened rectangular channels with Reynolds number ranging from 5000 to 20000 and uniform heat flux of 10kW/m2. Considering single-phase approach, the two-dimensional continuity, Navier-Stokes, and energy equations were solved by using the finite volume method (FVM). The optimization was carried out by using various rib shapes (rectangular shape, triangular shape, wedge pointing upstream, and wedge pointing downstream) in two arrangements (in-line and staggered) and three different aspect ratios (w/e=0.5, 2, and 4) to reach the optimal geometry with maximum performance evaluation criterion (PEC). The main aim of this study is to analyze the effects of nanoparticle types (Al2O3, CuO, SiO2, and ZnO), concentration (1-4%), and nanoparticle diameter (30-80nm), on the heat transfer and fluid flow characteristics. Simulation results show that the ribbed channels' performance was greatly influenced by rib shapes and their geometrical parameters. The highest PEC was obtained for the in-line triangular ribs with w/e=4 at Re=5000. It is found that the water-SiO2 shows the highest heat transfer enhancement compared with other tested nanofluids. The Nusselt number through the ribbed channels was enhanced with the increase of the particle volume fraction and Reynolds number, and with the decrease of nanoparticle diameter. © 2015 Elsevier Ltd.

Abdullah M.A.,University of Technology Malaysia | Yatim A.H.M.,University of Technology Malaysia | Tan C.W.,University of Technology Malaysia | Saidur R.,University of Malaya
Renewable and Sustainable Energy Reviews | Year: 2012

This paper reviews state of the art maximum power point tracking (MPPT) algorithms for wind energy systems. Due to the instantaneous changing nature of the wind, it is desirable to determine the one optimal generator speed that ensures maximum energy yield. Therefore, it is essential to include a controller that can track the maximum peak regardless of wind speed. The available MPPT algorithms can be classified as either with or without sensors, as well as according to the techniques used to locate the maximum peak. A comparison has been made between the performance of different MPPT algorithms on the basis of various speed responses and ability to achieve the maximum energy yield. Based on simulation results available in the literature, the optimal torque control (OTC) has been found to be the best MPPT method for wind energy systems due to its simplicity. On the other hand, the perturbation and observation (P&O) method is flexible and simple in implementation, but is less efficient and has difficulties determining the optimum step-size. © 2012 Elsevier Ltd. All rights reserved.

Nasir M.H.N.,University of Malaya | Sahibuddin S.,University of Technology Malaysia
Scientific Research and Essays | Year: 2011

Although there have been studies completed on the critical success factors of software projects, these studies all have been specific to one particular country. There has been no comprehensive study reporting on different project sizes in various domains and in multiple countries. We present our extensive literature survey of critical success factors that impact software projects. Forty-three articles from the years 1990 to 2010 were found to be significant contributions that could be analysed in order to develop a list of critical factors that specifically affect the success of software projects. The method of content analysis and frequency analysis was adopted. Twenty-six critical success factors were found to be related to software project success. We suggest that organisation or project manager is attentive to control the top five critical factors to drive towards project success since the percentage of frequency of occurrences for each is more than 50%. Also, it appears that non-technical factors (94%) dominated over technical factors (6%). In a result unique to our study compared with previous one, we found that the factors of clear and frozen requirements, realistic estimation of the schedule and budget, along with a competent project manager are the five most critical success factors of software projects. © 2011 Academic Journals.

Al-mulali U.,University of Technology Malaysia | Foon Tang C.,University of Malaya
Energy Policy | Year: 2013

This study investigated the validity of the pollution haven hypothesis in the Gulf Cooperation Council (GCC) countries using a multivariate framework. To achieve the goal of this study, the non-stationary panel techniques were used to examine the hypothesis from 1980 to 2009. Based on the Pedroni cointegration test results, it was found that the variables are cointegrated. Moreover, the Fully Modified OLS results showed that energy consumption and GDP growth increase CO2 emission while foreign direct investment inflows have a long run negative relationship with CO2 emission. Furthermore, based on the short run Granger causality test results, FDI has no short run causal relationship with CO2 emission and energy consumption while energy consumption and GDP growth have a positive causal relationship with CO2 emission. Thus, the results of this study indicate that energy consumption and GDP growth are the source of pollution in the GCC countries and not the foreign direct investment inflows. Thus, the study recommended that these countries should utilize policies to encourage inward foreign investment since it plays an important role in stimulating GDP growth. © 2013 Elsevier Ltd.

Enayatifar R.,University of Technology Malaysia | Sadaei H.J.,University of Technology Malaysia | Abdullah A.H.,University of Technology Malaysia | Gani A.,University of Malaya
Energy Conversion and Management | Year: 2013

In this study, a hybrid algorithm based on a refined high-order weighted fuzzy algorithm and an imperialist competitive algorithm (RHWFTS-ICA) is developed. This method is proposed to perform efficiently under short-term load forecasting (STLF). First, autocorrelation analysis was used to recognize the order of the fuzzy logical relationships. Next, the optimal coefficients and optimal intervals of adaption were obtained by means of an imperialist competitive algorithm in the training dataset. Lastly, the obtained information was employed to forecast the 48-step-ahead of the STLF problems. To validate the proposed method, eight case studies of real load data, collected from the UK and France during the years 2003 and 2004, were tested with the proposed algorithm and certain enhanced STLF forecasting models. The numerical results demonstrated the efficiency of the proposed algorithm in terms of the forecast accuracy. © 2013 Elsevier Ltd. All rights reserved.

Chan C.S.,University of Technology Malaysia | Chan K.-G.,University of Malaya | Tay Y.-L.,BioEasy Sdn Bhd. | Chua Y.-H.,BioEasy Sdn Bhd. | Goh K.M.,University of Technology Malaysia
Frontiers in Microbiology | Year: 2015

The Sungai Klah (SK) hot spring is the second hottest geothermal spring in Malaysia. This hot spring is a shallow, 150-m-long, fast-flowing stream, with temperatures varying from 50 to 110°C and a pH range of 7.0-9.0. Hidden within a wooded area, the SK hot spring is continually fed by plant litter, resulting in a relatively high degree of total organic content (TOC). In this study, a sample taken from the middle of the stream was analyzed at the 16S rRNA V3-V4 region by amplicon metagenome sequencing. Over 35 phyla were detected by analyzing the 16S rRNA data. Firmicutes and Proteobacteria represented approximately 57% of the microbiome. Approximately 70% of the detected thermophiles were strict anaerobes; however, Hydrogenobacter spp., obligate chemolithotrophic thermophiles, represented one of the major taxa. Several thermophilic photosynthetic microorganisms and acidothermophiles were also detected. Most of the phyla identified by 16S rRNA were also found using the shotgun metagenome approaches. The carbon, sulfur, and nitrogen metabolism within the SK hot spring community were evaluated by shotgun metagenome sequencing, and the data revealed diversity in terms of metabolic activity and dynamics. This hot spring has a rich diversified phylogenetic community partly due to its natural environment (plant litter, high TOC, and a shallow stream) and geochemical parameters (broad temperature and pH range). It is speculated that symbiotic relationships occur between the members of the community. © 015 Chan, Chan, Tay, Chua and Goh.

Lee Y.Y.,Universiti Sains Malaysia | Tee H.-P.,Hospital Tengku Ampuan Afzan | Mahadeva S.,University of Malaya
World Journal of Gastroenterology | Year: 2014

Bacterial infections are common in cirrhotic patients with acute variceal bleeding, occurring in 20% within 48 h. Outcomes including early rebleeding and failure to control bleeding are strongly associated with bacterial infection. However, mortality from variceal bleeding is largely determined by the severity of liver disease. Besides a higher Child-Pugh score, patients with hepatocellular carcinoma are particularly susceptible to infections. Despite several hypotheses that include increased use of instruments, greater risk of aspiration pneumonia and higher bacterial translocation, it remains debatable whether variceal bleeding results in infection or vice versa but studies suggest that antibiotic prophylaxis prior to endoscopy and up to 8 h is useful in reducing bacteremia and spontaneous bacterial peritonitis. Aerobic gram negative bacilli of enteric origin are most commonly isolated from cultures, but more recently, gram positives and quinolone-resistant organisms are increasingly seen, even though their clinical significance is unclear. Fluoroquinolones (including ciprofloxacin and norfloxacin) used for short term (7 d) have the most robust evidence and are recommended in most expert guidelines. Short term intravenous cephalosporin (especially ceftriaxone), given in a hospital setting with prevalent quinolone-resistant organisms, has been shown in studies to be beneficial, particularly in high risk patients with advanced cirrhosis. © 2014 Baishideng Publishing Group Co., Limited. All rights reserved.

Hosen M.A.,University of Malaya | Hussain M.A.,University of Malaya | Mjalli F.S.,Sultan Qaboos University
Control Engineering Practice | Year: 2011

Controlling batch polymerization reactors imposes great operational difficulties due to the complex reaction kinetics, inherent process nonlinearities and the continuous demand for running these reactors at varying operating conditions needed to produce different polymer grades. Model predictive control (MPC) has become the leading technology of advanced nonlinear control adopted for such chemical process industries. The usual practice for operating polymerization reactors is to optimize the reactor temperature profile since the end use properties of the product polymer depend highly on temperature. This is because the end use properties of the product polymer depend highly on temperature. The reactor is then run to track the optimized temperature set-point profile. In this work, a neural network-model predictive control (NN-MPC) algorithm was implemented to control the temperature of a polystyrene (PS) batch reactors and the controller set-point tracking and load rejection performance was investigated. In this approach, a neural network model is trained to predict the future process response over the specified horizon. The predictions are passed to a numerical optimization routine which attempts to minimize a specified cost function to calculate a suitable control signal at each sample instant. The performance results of the NN-MPC were compared with a conventional PID controller. Based on the experimental results, it is concluded that the NN-MPC performance is superior to the conventional PID controller especially during process startup. The NN-MPC resulted in smoother controller moves and less variability. © 2011 Elsevier Ltd.

Shahbaz K.,University of Malaya | Mjalli F.S.,Sultan Qaboos University | Hashim M.A.,University of Malaya | AlNashef I.M.,King Saud University
Energy and Fuels | Year: 2011

Biodiesel is a remarkable alternative to the decreasing resources for fossil fuels. One of the critical steps in producing biodiesel is its purification from the byproduct glycerol. The content of glycerol permissible must pass the EN 14214 and ASTM D6751 international biodiesel standards. In this work, methyl triphenyl phosphunium bromide as salt and three different hydrogen-bond donors, namely, glycerol, ethylene glycol, and triethylene glycol, were selected to synthesize three deep eutectic solvents (DESs). These DESs were employed as the solvent for the removal of glycerol from palm-oil-based biodiesel. The effects of DES type on the removal of free glycerol, bound glycerol, and total glycerol were investigated. The results revealed that the ethylene glycol DESs and triethylene glycol DESs were successful in removing all free glycerol from the palm-oil-based biodiesel. All tested DESs were able to reduce the content of monoglycerides (MGs) and diglycerides (DGs). Moreover, all used DESs had the tendency to reduce the DGs more effectively than removing MGs. The maximum removal efficiency of MGs and DGs was attained by triethylene-glycol-based DESs at a molar ratio of 3:1 (DES8:biodiesel) and 0.75:1 (DES8:biodiesel), with 37.9 and 53.4% removal, respectively. The total glycerol was reduced below the ASTM standards using all tested DESs. The DES:biodiesel molar ratios of 3:1 for DES4 and 3:1 for DES8 were found to be the most effective solvents for reducing total glycerol content, with 40 and 50% removal efficiency, respectively. © 2011 American Chemical Society.

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