George Town, Malaysia
George Town, Malaysia

Universiti Sains Malaysia is a public university in Malaysia. There are three campuses: one on the island of Penang , one in Kelantan , and one in Nibong Tebal . There is offshore collaboration with KLE University, India offering the Doctor of Medicine undergraduate degree. USM plans to open a Global Campus located at Kuala Lumpur Education City . With around 28,300 postgraduate and undergraduate students in 2009, USM is one of the biggest universities in terms of enrollment in Malaysia. The number of lecturers is about 1,479, which leads to a student-lecturer ratio of around 19:1. Wikipedia.


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Najafzadeh M.,Shahid Bahonar University of Kerman | Barani G.-A.,Shahid Bahonar University of Kerman | Azamathulla H.M.,Universiti Sains Malaysia
Applied Ocean Research | Year: 2013

This study presents new application of group method of data handling (GMDH) to predict scour depth around a vertical pier in cohesive soils. Quadratic polynomial was used to develop GMDH network. Back propagation algorithm has been utilized to adjust weighting coefficients of GMDH polynomial thorough trial and error method. Parameters such as initial water content, shear strength, compaction of cohesive bed materials, clay content of cohesive soils, and flow conditions are main factors affecting cohesive scour. Performances of the GMDH network were compared with those obtained using several traditional equations. The results indicated that the proposed GMDH-BP has produced quite better scour depth prediction than those obtained using traditional equations. To assign the most significant parameter on scour process in cohesive soils, sensitivity analysis was performed for the GMDH-BP network and the results showed that clay percentage was the most effective parameter on scour depth. The error parameter for three classes of IWC and Cp showed that the GMDH-BP model yielded better scour prediction in ranges of IWC = 36.3-42.28% and Cp = 35-100%. In particular application, the GMDH network was proved very successful compared to traditional equations. The GMDH network was presented as a new soft computing technique for the scour depth prediction around bridge pier in cohesive bed materials. © 2013 Elsevier Ltd.


Wong W.P.,Universiti Sains Malaysia | Jaruphongsa W.,Chulalongkorn University | Lee L.H.,National University of Singapore
IEEE Transactions on Automatic Control | Year: 2011

We analyze how to allocate the budget for data collection effectively when data envelopment analysis (DEA) is used for predicting the efficiency. We formulate this problem under a Bayesian framework and propose two heuristics algorithms, i.e., a gradient-based algorithm and a hybrid GA algorithm to solve this optimization problem. Our results indicate that effective allocation of budget for data collection can greatly reduce the overall data collection effort in comparison with a uniform budget allocation. © 2006 IEEE.


Mohamad Haafiz M.K.,University of Technology Malaysia | Mohamad Haafiz M.K.,Universiti Sains Malaysia | Hassan A.,University of Technology Malaysia | Jawaid M.,University Putra Malaysia
Carbohydrate Polymers | Year: 2013

In this work, we successfully isolated microcrystalline cellulose (MCC) from oil palm empty fruit bunch (OPEFB) fiber-total chlorine free (TCF) pulp using acid hydrolysis method. TCF pulp bleaching carried out using an oxygen-ozone-hydrogen peroxide bleaching sequence. Fourier transform infrared (FT-IR) spectroscopy indicates that acid hydrolysis does not affect the chemical structure of the cellulosic fragments. The morphology of the hydrolyzed MCC was investigated using scanning electron microscopy (SEM), showing a compact structure and a rough surface. Furthermore, atomic force microscopy (AFM) image of the surface indicates the presence of spherical features. X-ray diffraction (XRD) shows that the MCC produced is a cellulose-I polymorph, with 87% crystallinity. The MCC obtained from OPEFB-pulp is shown to have a good thermal stability. The potential for a range of applications such as green nano biocomposites reinforced with this form of MCC and pharmaceutical tableting material is discussed. © 2013 Elsevier Ltd.


Zhou Y.,Nanyang Environment and Water Research Institute | Oehmen A.,New University of Lisbon | Vadivelu V.,Universiti Sains Malaysia | Ng W.J.,Nanyang Environment and Water Research Institute
Water Research | Year: 2011

Nitrite is known to accumulate in wastewater treatment plants (WWTPs) under certain environmental conditions. The protonated form of nitrite, free nitrous acid (FNA), has been found to cause severe inhibition to numerous bioprocesses at WWTPs. However, this inhibitory effect of FNA may possibly be gainfully exploited, such as repressing nitrite oxidizing bacteria (NOB) growth to achieve N removal via the nitrite shortcut. However, the inhibition threshold of FNA to repress NOB (∼0.02mg HNO 2-N/L) may also inhibit other bioprocesses. This paper reviews the inhibitory effects of FNA on nitrifiers, denitrifiers, anammox bacteria, phosphorus accumulating organisms (PAO), methanogens, and other microorganisms in populations used in WWTPs. The possible inhibition mechanisms of FNA on microorganisms are discussed and compared. It is concluded that a single inhibition mechanism is not sufficient to explain the negative impacts of FNA on microbial metabolisms and that multiple inhibitory effects can be generated from FNA. The review would suggest further research is necessary before the FNA inhibition mechanisms can be more effectively used to optimize WWTP bioprocesses. Perspectives on research directions, how the outcomes may be used to manipulate bioprocesses and the overall implications of FNA on WWTPs are also discussed. © 2011 Elsevier Ltd.


Najafzadeh M.,Shahid Bahonar University of Kerman | Azamathulla H.M.,Universiti Sains Malaysia
Neural Computing and Applications | Year: 2013

In this study, group method of data handling network with quadratic polynomial was used to predict scour depth around bridge piers. Effective parameters on scour phenomena include sediment size, geometry of bridge pier, and upstream flow conditions. Different shapes of piers have been utilized to develop the GMDH network. Back propagation algorithm was performed to train the GHMD network which updated weighting coefficients of quadratic polynomial in each iteration of the training stage. The GMDH performed with the lowest errors of training and testing stages for cylindrical pier. Also, Richardson and Davis, Johnson's equations produced relatively good performances for different types of piers. Finally, the results indicated that GMDH could be provided more accurate prediction than those obtained using traditional equations. © 2012 Springer-Verlag London Limited.


Ramli M.,Universiti Sains Malaysia
Construction and Building Materials | Year: 2012

This study was conducted to investigate the mechanical properties and the durability by using of different percentages of steel fibre with high strength flowing concrete (HSFC) and also the use of the hybridization of steel fibres, palm fibres and synthetic fibre (Barchip). Compressive strength, splitting tensile strength, flexural strength, static modulus of elasticity and permeability tests were determined after normal water curing and seawater exposure. The results show that the uses of 0.25-0.5% of the palm and Barchip fibres with 1.5-1.75% of steel fibre in HSFC mixes boost the best performance of compressive strength, splitting tensile strength, flexural strength among others. Besides, these percentages of fibres inclusions in HSFC were found to be effective when the HSFC exposed to seawater. © 2012 Elsevier Ltd. All rights reserved.


Ang W.L.,National University of Malaysia | Mohammad A.W.,National University of Malaysia | Hilal N.,University of Swansea | Leo C.P.,Universiti Sains Malaysia
Desalination | Year: 2015

Conventional processes involved in water treatment, either in water treatment plants or reverse osmosis desalination plants, have encountered several obstacles that have severely affected their performances and efficiencies. Pollution of natural water resources, increasing demand and overuse of clean water have all put critical stress on currently available conventional water treatment/desalination plants. Due to these problems, integrated/hybrid membrane processes have attracted much interest. An integrated/hybrid membrane system is a process which combines a membrane filtration unit (microfiltration/ultrafiltration/nanofiltration) with other processes such as coagulation, adsorption and ion exchange. Alternatively, it can be a combination of different membranes in the same system with a conventional process. The purpose of this paper is to review the applicability of integrated/hybrid membrane systems in water treatment plants and reverse osmosis desalination plants. The literature shows that many benefits and marked improvements could be achieved with integrated/hybrid membrane processes, such as enhanced quality of the water produced, energy savings, environmental friendliness, and reductions in the capital and operating costs of the plants. The implications of the integrated membrane system prove that it has huge potential to be widely applied and can lead to a breakthrough in solving the problem of water scarcity. © 2014 Elsevier B.V.


Tan K.T.,Universiti Sains Malaysia | Tan K.T.,University Tunku Abdul Rahman | Lee K.T.,Universiti Sains Malaysia | Ahmad Z.,Universiti Sains Malaysia
Applied Energy | Year: 2013

Biodiesel production by non-catalytic supercritical methyl acetate (SCMA) reaction has been developed and optimized in previous study using Jatropha oil as oil feedstock. The reaction produces fatty methyl acid esters (FAME) as well as triacetin as the co-product. Due to the requirement of high reaction temperatures in SCMA treatment, thus the thermal stability of methyl oleate and methyl linoleate which are the major FAME in SCMA was investigated at temperature ranging from 330. °C to 420. °C. In addition, thermal stability of triacetin which was utilized as fuel additive in biodiesel was also investigated. The results revealed that the thermal stability of poly-unsaturated methyl linoleate decreases dramatically as temperature is increased from 330. °C to 420. °C while degradation of methyl oleate was only significant at 390. °C and above. Similar behaviour was also observed for triacetin which was found to degrade at high temperatures, resulting in low yield of biodiesel fuel even at optimum conditions. © 2012 Elsevier Ltd.


Khan Z.A.,Jamia Millia Islamia University | Kamaruddin S.,Universiti Sains Malaysia | Siddiquee A.N.,Jamia Millia Islamia University
Materials and Design | Year: 2010

Usability of recycled High Density Polyethylene (HDPE) as substitute for virgin HDPE is investigated. Optimization design of the injection moulding parameters for recycled HDPE products is presented. Tensile, compressive and flexural strengths are selected to evaluate the process performance and the corresponding moulding parameters are melt temperature, holding pressure, injection time, and holding time. Optimal combination of injection moulding parameters is determined using Grey relational analysis. The principal component analysis is applied to evaluate the weighting values corresponding to various performance characteristics. Tensile, compressive and flexural strengths of the recycled HDPE are found close to that of virgin HDPE. Thus, recycled HDPE is a good substitute for virgin HDPE. Optimal combination of the process parameters for the multi-performance characteristics of the recycled HDPE is the set with melt temperature at 240 °C, holding pressure at 255 N/m2, injection time at 0.6 s and holding time at 30 s. © 2009 Elsevier Ltd. All rights reserved.


Ng L.Y.,National University of Malaysia | Mohammad A.W.,National University of Malaysia | Leo C.P.,Universiti Sains Malaysia | Hilal N.,University of Swansea
Desalination | Year: 2013

Synthetic membranes have become the focus of separation processes in different industries. Synthetic membranes may be composed of inorganic materials (such as ceramics) and organic materials (such as polymers). Current research on membranes focus more on polymeric membranes due to better control of the pore forming mechanism, higher flexibility, smaller spaces required for installation and lower costs compared to inorganic membranes. Though polymeric membranes have these properties which make them better materials in membrane fabrication, they also have some disadvantages which need to be overcome. Common problems faced by polymeric membranes, such as high hydrophobicity, exposure to biofouling, low fluxes and low mechanical strength have become the focus of researchers in order to improve these disadvantages. The incorporation of nanoparticles into polymeric membranes has been the trend in the field of membrane research recently. Incorporation of nano-sized materials could produce synergistic effects when incorporated with different types of materials. This paper discusses a few types of nanoparticles incorporated into various types of polymeric membranes. Nanoparticles that will be discussed include silver, iron, zirconium, silica, aluminium, titanium, and magnesium based nanoparticles. Nanoparticles affect the permeability, selectivity, hydrophilicity, conductivity, mechanical strength, thermal stability, and the antiviral and antibacterial properties of the polymeric membranes. Though nanoparticles usually improve the performances of the membranes, they also might change or even deteriorate the performances of the membranes. Thus, careful study needs to be done in order to choose the most appropriate types and composition of nanoparticles to be incorporated into polymeric membranes. © 2010 Elsevier B.V.


Chan H.-K.,Sultanah Bahiyah Hospital | Hassali M.A.,Universiti Sains Malaysia
International Journal of Clinical Pharmacy | Year: 2014

Background Inability to read instructions on drug labels has been identified among the Malaysian population since 1990′s. Objective To assess the impact of font-enlarged and pictogram-incorporated labels used for long-term medications on patients’ adherence, comprehension and preferences. Setting Outpatient pharmacy in one of the major general hospitals across Northern Malaysia. Method This was a three-arm, randomized controlled trial. Outpatients with refill prescriptions of selected oral antihypertensive or antidiabetic medications were screened for eligibility. They were randomly allocated with standard (n = 35), font-enlarged (n = 40) or pictogram-incorporated (n = 35) labels. Assessment of baseline adherence scores using the 8-item Morisky Medication Adherence Scale, comprehension scores using a structured questionnaire and preferences was conducted upon recruitment. Follow-up telephone interviews were conducted after 4 weeks. Main outcome measure The changes of patients’ adherence and comprehension scores and their preferences. Results Within-group comparisons demonstrated an increase of total adherence scores after 4 weeks in all three groups (mean changes 0.35, 0.58 and 0.67; p = 0.029, 0.013 and 0.011, respectively). The repeatedly measured total comprehension score of pictogram-incorporated label group was significantly higher than baseline (mean change 0.37, p = 0.010). Two intervention groups obtained significantly higher scores for few items in both adherence and comprehension measurements after 4 weeks as compared with baselines. As indicated by F tests, three groups did not significantly differ in the changes of both total adherence and comprehension scores (p = 0.573 and 0.069, respectively) with the subjects’ age adjusted. Elderlies and those with a higher number of morbidity preferred pictogram-incorporated label over font-enlarged label. Conclusion We did not find a significant change of both adherence and comprehension levels after the introduction of modified medication labels. However, on the basis of within-group comparisons, they may have positive influences on certain aspects of patients’ adherence and comprehension. Variations in preferences may reflect the unique need of different subgroups in receiving written medication instructions. © 2014, Koninklijke Nederlandse Maatschappij ter bevordering der Pharmacie.


Lahijani P.,Universiti Sains Malaysia | Zainal Z.A.,Universiti Sains Malaysia | Mohamed A.R.,Universiti Sains Malaysia | Mohammadi M.,Noushirvani University of Technology
Bioresource Technology | Year: 2013

Palm empty fruit bunch ash (EFB-ash) was used as a natural catalyst, rich in potassium to enhance the CO2 gasification reactivity of palm shell char (PS-char). Various EFB-ash loadings (ranging from 0 to 12.5wt.%) were implemented to improve the reactivity of PS-char during CO2 gasification studies using thermogravimetric analysis. The achieved results explored that the highest gasification reactivity was devoted to 10% EFB-ash loaded char. The SEM-EDS and XRD analyses further confirmed the successful loading of EFB-ash on PS-char which contributed to promoting the gasification reactivity of char. Random pore model was applied to determine the kinetic parameters in catalytic gasification of char at various temperatures of 800-900°C. The dependence of char reaction rate on gasification temperature resulted in a straight line in Arrhenius-type plot, from which the activation energy of 158.75kJ/mol was obtained for the catalytic char gasification. © 2012 Elsevier Ltd.


Lahijani P.,Universiti Sains Malaysia | Zainal Z.A.,Universiti Sains Malaysia | Mohamed A.R.,Universiti Sains Malaysia | Mohammadi M.,Noushirvani University of Technology
Bioresource Technology | Year: 2013

In this investigation, palm empty fruit bunch (EFB) and almond shell (AS) were implemented as two natural catalysts rich in alkali metals, especially potassium, to enhance the reactivity of tire-char through co-gasification process. Co-gasification experiments were conducted at several blending ratios using isothermal Thermogravimetric analysis (TGA) under CO2. The pronounced effect of inherent alkali content of biomass-chars on promoting the reactivity of tire-char was proven when acid-treated biomass-chars did not exert any catalytic effect on improving the reactivity of tire-char in co-gasification experiments. In kinetic studies of the co-gasified samples in chemically-controlled regime, modified random pore model (M-RPM) was adopted to describe the reactive behavior of the tire-char/biomass-char blends. By virtue of the catalytic effect of biomass, the activation energy for tire-char gasification was lowered from 250kJ/mol in pure form 203 to 187kJ/mol for AS-char and EFB-char co-gasified samples, respectively. © 2013 Elsevier Ltd.


Lahijani P.,Universiti Sains Malaysia | Zainal Z.A.,Universiti Sains Malaysia | Mohamed A.R.,Universiti Sains Malaysia | Mohammadi M.,Noushirvani University of Technology
Bioresource Technology | Year: 2013

This study investigates the influence of alkali (Na, K), alkaline earth (Ca, Mg) and transition (Fe) metal nitrates on CO2 gasification reactivity of pistachio nut shell (PNS) char. The preliminary gasification experiments were performed in thermogravimetric analyzer (TGA) and the results showed considerable improvement in carbon conversion; Na-char>Ca-char>Fe-char>K-char>Mg-char>raw char. Based on TGA studies, NaNO3 (with loadings of 3-7wt%) was selected as the superior catalyst for further gasification studies in bench-scale reactor; the highest reactivity was devoted to 5wt% Na loaded char. The data acquired for gasification rate of catalyzed char were fitted with several kinetic models, among which, random pore model was adopted as the best model. Based on obtained gasification rate constant and using the Arrhenius plot, activation energy of 5wt% Na loaded char was calculated as 151.46kJ/mol which was 53kJ/mol lower than that of un-catalyzed char. © 2013 Elsevier Ltd.


Al-Heuseen K.,Al - Balqa Applied University | Hashim M.R.,Universiti Sains Malaysia
Sensors and Actuators, B: Chemical | Year: 2012

This paper reports the studies of Pd Schottky contact on porous n-GaN for hydrogen gas sensor. A simple conventional and low cost photoelectrochemical etching method was used to produce porous GaN with high uniformity. Hydrogen sensor was subsequently fabricated by depositing Pd Schottky contacts onto the porous GaN sample. For comparative study, a standard hydrogen sensor was also prepared by depositing Pd Schottky contacts on the as-grown sample. The Pd/porous GaN sensor exhibited a significant change of current upon exposure to different flow rates of 2% H 2 in N 2 gas as compared to the standard Pd/GaN sensor. The response increased exponentially with hydrogen flow rate for both sensors, but Pd/porous GaN is more sensitive to hydrogen than that of the as-grown GaN. The values of ideality factor (n), barrier height (φ B) and series resistance (R s) were calculated in both sensors. Barrier heights and series resistance decreased with H 2 flow rate while ideality factor increased. © 2012 Elsevier B.V. All rights reserved.


Iqbal S.,Universiti Sains Malaysia | Besar R.,Multimedia University | Venkataseshaiah C.,Multimedia University
Journal of Instrumentation | Year: 2010

This paper proposes a dual-mode phase-shift modulation control scheme for series resonant inverter fed voltage multiplier (VM) based X-ray power supply. In this control scheme the outputs voltage of two parallel connected series resonant inverters are mixed before supplying to VM circuit. The output voltage of the power supply is controlled by varying the phase-shift between the output voltages of two inverters. In order to achieve quick rise of output voltage, the power supply is started with zero phase-shift and as the output voltage reaches 90% of the target voltage, the phase-shift is increased to a value which corresponds to target output voltage to prevent overshoot. The proposed control scheme has been shown to have good performance. Experimental results based on the scaled-down laboratory prototype are presented to validate the effectiveness of proposed dual-mode phase shift modulation control scheme. © 2010 IOP Publishing Ltd and SISSA.


Lee Y.Y.,Universiti Sains Malaysia | Erdogan A.,Georgia Regents University | Rao S.S.C.,Georgia Regents University
Journal of Neurogastroenterology and Motility | Year: 2014

Assessment of transit through the gastrointestinal tract provides useful information regarding gut physiology and pathophysiology. Although several methods are available, each has distinct advantages and limitations. Recently, an ingestible wireless motility capsule (WMC), similar to capsule video endoscopy, has become available that offers a less-invasive, standardized, radiation-free and office-based test. The capsule has 3 sensors for measurement of pH, pressure and temperature, and collectively the information provided by these sensors is used to measure gastric emptying time, small bowel transit time, colonic transit time and whole gut transit time. Current approved indications for the test include the evaluation of gastric emptying in gastroparesis, colonic transit in constipation and evaluation of generalised dysmotility. Rare capsule retention and malfunction are known limitations and some patients may experience difficulty with swallowing the capsule. The use of WMC has been validated for the assessment of gastrointestinal transit. The normal range for transit time includes the following: gastric emptying (2-5 hours), small bowel transit (2-6 hours), colonic transit (10-59 hours) and whole gut transit (10-73 hours). Besides avoiding the use of multiple endoscopic, radiologic and functional gastrointestinal tests, WMC can provide new diagnoses, leads to a change in management decision and help to direct further focused work-ups in patients with suspected disordered motility. In conclusion, WMC represents a significant advance in the assessment of segmental and whole gut transit and motility, and could prove to be an indispensable diagnostic tool for gastrointestinal physicians worldwide. © 2014 The Korean Society of Neurogastroenterology and Motility.


Mohamed A.R.,Universiti Sains Malaysia | Mohammadi M.,Noushirvani University of Technology | Darzi G.N.,Noushirvani University of Technology
Renewable and Sustainable Energy Reviews | Year: 2010

A literature review on preparation of carbon molecular sieve (CMS) from lignocellulosic biomass is presented. The effect of various operation parameters such as pyrolytic temperature, flow rate of the carbonizing agent and time of pyrolysis on the carbonization of the lignocellulosic biomass as a carbon precursor was reviewed. Various physical and chemical processes for the activation of the biomass-based char and their effects on textural properties of the activated char were discussed. Conversion of activated chars to CMS as the final stage of the preparation process through different techniques of chemical vapor deposition (CVD) and controlled pyrolysis was assessed. Survey of literature revealed that production of CMS with BET surface area of 1247 m2/g and micropore volume of 0.51 cm3/g, under appropriate conditions has been reported. Also, maximum selectivity of 7.6 and 400 for separation of O2/N2 and CO2/CH4 was devoted to palm shell and coconut shell-based CMS, respectively. © 2010 Elsevier Ltd. All rights reserved.


Al-Mulali U.,Multimedia University | Ozturk I.,Cag University | Lean H.H.,Universiti Sains Malaysia
Natural Hazards | Year: 2015

This study investigates the influence of disaggregated renewable electricity production by source on CO2 emission in 23 selected European countries for the period of 1990–2013. Panel data techniques were used in examining the relationships. The Pedroni cointegration results indicated that CO2 emission, GDP growth, urbanization, financial development, and renewable electricity production by source were cointegrated. Moreover, the fully modified ordinary least-square results revealed that GDP growth, urbanization, and financial development increase CO2 emission in the long run, while trade openness reduces it. Furthermore, renewable electricity generated from combustible renewables and waste, hydroelectricity, and nuclear power have a negative long-run effect on CO2 emission, while renewable electricity generated from solar power and wind power is insignificant. The VECM Granger causality also revealed that GDP growth is the only variable that has causal effects on CO2 emission in all the investigated models, while the rest of the variables have causal effects on CO2 emission in only a few models. A number of policy recommendations were provided for the European countries. © 2015, Springer Science+Business Media Dordrecht.


European and Southeast Asian ICT R&D collaboration has a successful and long history, but opportunities exist to create more synergies, leverage and value added. In order to secure higher and sustainable impacts, we propose to implement an intensified targeted support at the appropriate scale, involving EU and SEA Research, Development and Innovation knowledge networks, clusters and their organisations: a structured bottom up - top down approach helping to create synergies between research and innovation programmes in the EU and the SEA region and create sustainable strategic partnerships. The action will pave the way for jointly addressing important societal challenges and core technologies, at the research, innovation and policy levels under HORIZON2020 and relevant SEA regional and national programmes.\nWithin this context, and building on the results and lessons learnt from the previous collaborative actions, the project has a three-fold objective: (1) To support internationalisation of European and SEA ICT-related research, development and innovation knowledge networks, technology platforms, clusters, organisations in the topics of common interest, in order to foster ICT RDI collaboration; (2) To promote Horizon 2020 and to reinforce synergies between the EU and ASEAN research development and innovation programmes; (3) To enrich and support EU-SEA ICT R&D policy dialogue, by supporting policy initiatives, summarising feedback from collaborative experience and proposing recommendations to reinforce EU-SEA ICT RDI collaboration.\nSpecialists from EU and SEA knowledge networks - ETPs, Networks of Excellence, clusters, projects, organisations - will be invited to participate in the internationalisation process with their counterparts working on similar strategic topics and societal challenges. The CONNECT2SEA fund distributed via a call for participants will support the establishment of new collaborations. The project will contribute to promotion of Horizon2020 and collaboration opportunities. Pilot actions will be implemented, to support policy initatives. The feedback will contribute to policy recommendations.


Lean H.H.,Universiti Sains Malaysia | Smyth R.,Monash University
Urban Studies | Year: 2013

This paper applies univariate and panel Lagrange multiplier (LM) unit root tests with one and two structural breaks to the ratio of the regional to national house price to examine the ripple effect for five different housing price indices (aggregate housing, detached housing, semi-detached housing, terrace housing and high-rise housing) across 14 regional locations in Malaysia. Segmentation is restricted to a small group of states across most housing types for which there is no long-run relationship with the Malaysian average. When all housing types are taken together, evidence of a ripple effect is generally found from the most developed states to the less developed states of Malaysia. While overall rates of conversion to the long-run equilibrium are consistent with a low level of persistence, there is some evidence of regional clusters based on similar speeds of adjustment in different parts of the country. © 2012 Urban Studies Journal Limited.


Lean H.H.,Universiti Sains Malaysia | Smyth R.,Monash University
Renewable and Sustainable Energy Reviews | Year: 2013

This study examines whether policies to promote renewable electricity generation are likely to be effective by applying panel unit root and stationarity tests to time series data on renewable electricity generation for 115 countries over the period 1980-2008. We find that for the panel as a whole, and almost three quarters of the individual countries, renewable electricity generation is characterized by a unit root. This result implies that policies to promote renewable electricity generation, such as renewable portfolio standards, which result in annual increases in renewable energy and, as such, which represent permanent positive shocks to the long-run growth path of renewable electricity generation, will be more effective in increasing renewable electricity generation than policies with a pre-specified time horizon. © 2013 Elsevier Ltd.


Elnaggar M.H.A.,Universiti Sains Malaysia | Abdullah M.Z.,Universiti Sains Malaysia | Abdul Mujeebu M.,Visvesvaraya Technological University
Energy Conversion and Management | Year: 2012

As part of the ongoing research on finned U-shape heat pipes for CPU cooling, the present work focuses on the characterization of working fluid in vertically oriented twin U-shape heat pipe, by taking into account the gravity of flow. Two-dimensional FE simulation is performed under natural and forced convection modes, by using ansys-flotran. The best heat input and coolant velocity for the simulations are determined experimentally, corresponding to the least thermal resistance. The wall temperatures at the evaporator, adiabatic and condenser sections, and the velocity and pressure distributions of vapor and liquid, are analyzed. The total heat input for minimum thermal resistance in both natural and forced convection is found to be 50 W, and the coolant velocity is 3 m/s. The predicted and experimental wall temperatures are found in excellent match. It is observed that for the present U-shape heat pipe configuration, the difference in evaporator and condenser temperatures is significantly small, resulting in enhanced heat transfer compared to the conventional heat pipes. The sintered copper wick has a small pore size, resulting in low wick permeability, leading to the generation of high capillary forces for anti-gravity applications. © 2012 Elsevier Ltd. All rights reserved.


Whittaker A.,Monash University | Chee H.L.,Universiti Sains Malaysia
Social Science and Medicine | Year: 2014

The growing trade in patients seeking health care in other countries, or medical travel, is changing the forms and experiences of health care seeking and producing changes to hospitals in terms of their design, organization and spaces. What is termed in marketing parlance in Thailand as an 'international hospital' oriented to attracting foreign patients, is a hotel-hospital hybrid that is locally produced through the inflexion of local practices to make a therapeutic space for international patients. The paper reports on work undertaken within a Thai hospital in 2012 which included observations and interviews with thirty foreign in-patients and nine informal interviews with hospital staff. Although theorized as a culturally neutral transnational 'space of connectivity', we show how cross-cultural tensions affect the experience of the hospital with implications for the organization of the hospital and notions of 'cultural competence' in care. There is no single universal experience of this space, instead, there are multiple experiences of the 'international hospital', depending on who patients are, where they are from, their expectations and relationships. Such hospitals straddle the expectations of both local patients and international clientele and present highly complex cross-cultural interactions between staff and patients but also between patients and other patients. Spatial organisation within such settings may either highlight cultural difference or help create culturally safe spaces. © 2014 Elsevier Ltd.


Junaidi M.U.M.,Universiti Sains Malaysia | Leo C.P.,Universiti Sains Malaysia | Ahmad A.L.,Universiti Sains Malaysia | Kamal S.N.M.,Universiti Sains Malaysia | Chew T.L.,University Tunku Abdul Rahman
Fuel Processing Technology | Year: 2014

Tradeoff limitation on selectivity and permeability restricts the use of membranes for CO2 separation in natural gas industry. Mixed matrix membranes (MMMs) with combined advantages of polymeric matrix and inorganic fillers have been long proposed to overcome this shortcoming, but thick dense symmetric layer structure with a high mass resistance offers improvement in selectivity only. In this study, asymmetric polysulfone MMMs incorporated with small pore zeolite were proposed. SAPO-34 zeolite with a framework of 0.38 nm pore size and high CO2 adsorption affinity was used as inorganic fillers. The asymmetric mixed matrix membrane structure was prepared using the phase inversion method. The effects of zeolite loading (5-30 wt.%) on the membrane characteristics were studied using SEM with EDX, FT-IR, and TGA; while the gas transport properties were investigated using pure gas permeation tests of N2, CO2 and CH4. Well dispersion of SAPO-34 particles in the polymer matrix was observed for zeolite loading less than 10 wt.%. The maximum CO2 permeance (314.02 GPU) was achieved by incorporating 10 wt.% of SAPO-34 into asymmetric PSf membrane. Even without strong binding between PSf and SAPO-34, CO2/N2 and CO 2/CH4 selectivities up to 26.1 and 28.2 respectively were observed. © 2013 Elsevier B.V. © 2013 Elsevier B.V. All rights reserved.


Anis S.,Universiti Sains Malaysia | Anis S.,State University of Semarang | Zainal Z.A.,Universiti Sains Malaysia
Renewable and Sustainable Energy Reviews | Year: 2011

Biomass gasification presents highly interesting possibilities for expanding the utilization of biomass as power generation using internal combustion engines or turbines. However, the need to reduce the tar in the producer gas is very important. The successful application of producer gas depends not only on the quantity of tar, but also on its properties and compositions, which is associated with the dew-point of tar components. Class 5, 4, and 2 tar become a major cause of condensation which can foul the engines and turbines. Hence, the selectivity of tar treatment method to remove or convert class 5, 4, and 2 tar is a challenge in producer gas utilization. This review was conducted to present the recent studies in tar treatment from biomass gasification. The new technologies with their strengths and the weaknesses in term of tar reduction are discussed. © 2011 Elsevier Ltd. All rights reserved.


Azamathulla H.M.,Universiti Sains Malaysia | Zahiri A.,Gorgan University of Agricultural Sciences and Natural Resources
Journal of Hydrology | Year: 2012

Flow discharge determination in rivers is one of the key elements in mathematical modelling in the design of river engineering projects. Because of the inundation of floodplains and sudden changes in river geometry, flow resistance equations are not applicable for compound channels. Therefore, many approaches have been developed for modification of flow discharge computations. Most of these methods have satisfactory results only in laboratory flumes. Due to the ability to model complex phenomena, the artificial intelligence methods have recently been employed for wide applications in various fields of water engineering. Linear genetic programming (LGP), a branch of artificial intelligence methods, is able to optimise the model structure and its components and to derive an explicit equation based on the variables of the phenomena. In this paper, a precise dimensionless equation has been derived for prediction of flood discharge using LGP. The proposed model was developed using published data compiled for stage-discharge data sets for 394 laboratories, and field of 30 compound channels. The results indicate that the LGP model has a better performance than the existing models. © 2012 Elsevier B.V.


Lean H.H.,Universiti Sains Malaysia | Smyth R.,Monash University
Applied Energy | Year: 2010

This study examines the causal relationship between carbon dioxide emissions, electricity consumption and economic growth within a panel vector error correction model for five ASEAN countries over the period 1980-2006. The long-run estimates indicate that there is a statistically significant positive association between electricity consumption and emissions and a non-linear relationship between emissions and real output, consistent with the environmental Kuznets curve. The long-run estimates, however, do not indicate the direction of causality between the variables. The results from the Granger causality tests suggest that in the long-run there is unidirectional Granger causality running from electricity consumption and emissions to economic growth. The results also point to unidirectional Granger causality running from emissions to electricity consumption in the short-run. © 2010 Elsevier Ltd. All rights reserved.


Lean H.H.,Universiti Sains Malaysia | Smyth R.,Monash University
Applied Energy | Year: 2010

This paper employs annual data from 1971 to 2006 to examine the causal relationship between aggregate output, electricity consumption, exports, labor and capital in a multivariate model for Malaysia. We find that there is bidirectional Granger causality running between aggregate output and electricity consumption. The policy implication of this result is that Malaysia should adopt the dual strategy of increasing investment in electricity infrastructure and stepping up electricity conservation policies to reduce unnecessary wastage of electricity, in order to avoid the negative effect of reducing electricity consumption on aggregate output. We also find support for the export-led hypothesis which states Granger causality runs from exports to aggregate output. This result is consistent with Malaysia pursuing a successful export-orientated strategy. © 2009 Elsevier Ltd. All rights reserved.


Lean H.H.,Universiti Sains Malaysia | Smyth R.,Monash University
Energy | Year: 2010

This paper employs annual data for Malaysia from 1970 to 2008 to examine the causal relationship between economic growth, electricity generation, exports and prices in a multivariate model. We find that there is unidirectional Granger causality running from economic growth to electricity generation. However, neither the export-led nor handmaiden theories of trade are supported and there is no causal relationship between prices and economic growth. The policy implication of this result is that electricity conservation policies, including efficiency improvement measures and demand management policies, which are designed to reduce the wastage of electricity and curtail generation can be implemented without having an adverse effect on Malaysia's economic growth. © 2010 Elsevier Ltd.


Zahiri A.,Gorgan University of Agricultural Sciences and Natural Resources | Azamathulla H.,Universiti Sains Malaysia | Bagheri S.,Gorgan University of Agricultural Sciences and Natural Resources
Journal of Hydrology | Year: 2013

Side weirs are one of the most common diversion structures used for flow control, irrigation, drainage networks, and waste-water channels. Side weirs are generally rectangular sharp crested in form and hence, have some limitations in precise flow measurement. For accurate flow measurement and management in wide range of discharges, use of compound side weirs are suggested in this study. Experiments have been carried out in a rectangular compound side weir with variable heights and widths. It was determined that discharge coefficient of a compound side weir is a function of upstream Froude number (Fr1), ratio of weighted crest height of weir to upstream water depth w̄/y1 and ratio of weir length to upstream water depth (L/y1). Based on the experimental data and regression modeling, a dimensionless equation has been developed for prediction of the discharge coefficient and an equation has been proposed for estimation of flow discharge in compound rectangular sharp crested side weirs. Through comparison of results of these equations and experimental data, good agreement was achieved. The mean and maximum relative errors of the discharge equation were -2.3% and 10.7%, respectively. © 2012 Elsevier B.V.


Ang G.T.,Universiti Sains Malaysia | Tan K.T.,Universiti Sains Malaysia | Tan K.T.,University Tunku Abdul Rahman | Lee K.T.,Universiti Sains Malaysia
Renewable and Sustainable Energy Reviews | Year: 2014

In this review, recent development of glycerol-free supercritical fluid transesterification for biodiesel production was discussed. Glycerol-free supercritical fluid processes including single-step and two-step transesterification for biodiesel production were reviewed and subsequently the advantages and limitations were highlighted. Value-Added by-product from glycerol-free production such as triacetin is more profitable compared with glycerol produced in conventional biodiesel production. Furthermore, the quality of biodiesel could be enhanced with the presence of triacetin, which is co-produced in supercritical methyl acetate transesterification reaction. However, there are concerns regarding the huge energy required to conduct supercritical reaction at elevated temperature and pressure. Hence, economic consideration in terms of equipment needed and profit margin were discussed in order to study the profitability of glycerol-free supercritical biodiesel production in the industry. Results showed that glycerol-free supercritical dimethyl carbonate process has the highest profit margin, indicating that it is economically competitive and could provide larger revenue to biodiesel producers. © 2013 Elsevier Ltd.


Lean H.H.,Universiti Sains Malaysia | Smyth R.,Monash University
Renewable and Sustainable Energy Reviews | Year: 2014

The objective of this paper is to examine whether energy consumption in Malaysia, disaggregated by sector and type, is stationary or contains a unit root. To realize our objective we apply the Lagrange multiplier (LM) family of unit root tests with up to two structural breaks. Depending on the decision rule for selecting between results in the no-break, one-break and two-break cases, we find that energy consumption is stationary for between 50 per cent and 70 per cent of the disaggregated energy series and between 25 per cent and 50 per cent of sectors. Implications for the Malaysian government's attempts to reduce fossil fuel consumption are discussed. © 2013 Elsevier Ltd.


Lean H.H.,Universiti Sains Malaysia | Smyth R.,Monash University
Applied Energy | Year: 2013

This study examines the integration properties of total renewable energy production, as well as production of biofuels and biomass in the United States. To do so we use Lagrange Multiplier (LM) univariate unit root tests with up to two structural breaks. We conclude that each production series has a unit root. The result suggests that random shocks, encompassing changes to regulation, to renewable energy production may lead to permanent departures from predetermined target levels. Furthermore, this result implies that permanent positive shocks (such as renewable portfolio standards) that increases the production of renewable energy resources will realize more in terms of positively altering the energy mix between renewable energy and energy from fossil fuels than temporary policy stances (such as investment tax credits over a predetermined time horizon). © 2012 Elsevier Ltd.


Tehrani R.M.A.,Islamic Azad University at Tehran | Ghadimi H.,Universiti Sains Malaysia | Ab Ghani S.,Universiti Sains Malaysia
Sensors and Actuators, B: Chemical | Year: 2013

A voltammetric sensor for hydroquinone (HQ) and catechol (CC) was developed. This was realized by modifying a glassy carbon electrode with composite film of graphene nanosheet and poly(4-vinylpyridine) (GR-P4VP/GCE). The smaller peak potential separation (ΔEp) of the GR-P4VP/GCE indicates the electrode process is very reversible as a result of increase in kinetics of electron transfer as and when P4VP was present in the modified electrode as compared to the GR/GCE and bare GCE. The proposed electrode has displayed a synergistic effect of P4VP and GR on the electrocatalytic oxidation of CC and HQ in sodium sulphate buffer solution (pH 2.5). The anodic peak potential, Epa, of both were clearly resolved in either cyclic voltammetry or differential pulse voltammetry which made simultaneous determination of both compounds possible. The GR-P4VP/GCE has exhibited excellent sensitivities in the measurement of HQ and CC with detection limits of 8.1 nM and 26 nM, respectively. The GR-P4VP/GCE developed was not interfered by traditional interferences, viz. phenol, nitrophenol, aminophenols, bisphenol A and chlorophenols. The GR-P4VP/GCE was successfully applied for simultaneous detection of spikes HQ and CC in tap water and lake water with encouraging results. © 2012 Elsevier B.V.


Tehrani R.M.A.,Islamic Azad University at Tehran | Ab Ghani S.,Universiti Sains Malaysia
Electrochimica Acta | Year: 2012

This study reports the success of using an electrosynthesized nanocrystalline hexagonal close-packed (hcp) nickel (Ni) modified composite graphite (CG) electrode for the electrocatalytic oxidation of glycerol in alkaline medium (0.1 M KOH). The hcp-nano Ni modified CG had an improved response and remarkable electrocatalytic oxidation of glycerol over the bare CG. The electrocatalysis was the result of the formation of NiOOH during the oxidation process. The process was influenced by the scan rate and concentration of glycerol. A linear relationship between the concentrations of glycerol with the current was obtained over a range of 0.5-12.0 mM glycerol, with a limit of detection (S/N = 3) at 0.033 mM glycerol. The hcp-nano Ni modified CG electrode was applied to directly determine the free glycerol concentration in the biodiesel samples. As a glycerol sensor, the hcp-nano Ni modified CG is quite stable. © 2012 Elsevier Ltd. All rights reserved.


Yen S.T.,University of Tennessee at Knoxville | Tan A.K.G.,Universiti Sains Malaysia
International Journal of Public Health | Year: 2012

Objective To investigate the roles of sociodemographic factors in fruit and vegetable (FV) consumption in Malaysia. Methods Data are obtained from the Malaysia Non-Communicable Disease Surveillance-1. Logistic regressions are conducted using a multiracial (Malay, Chinese, Indian and other ethnic groups) sample of 2,447 observations to examine the factors affecting individual decisions to consume FV on a daily basis. Results Based on the binary outcomes of whether individuals consumed FV daily, results indicate that work hours, education, age ethnicity, income, gender, smoking status, and location of residence are significantly correlated with daily fruit consumption. Daily vegetable consumption is significantly correlated with income, gender, health condition, and location of residence. Conclusions Our results imply the need for programs to educate and motivate consumers to make healthier dietary choices. Interventions to increase FV consumption by changing behaviors should be considered, as should those that increase public awareness of the dietary benefits of FV. These intervention programs should be targeted at and tailored toward individuals who are less educated, younger, less affluent, males, smokers, and metropolitan dwellers. © 2012 Swiss School of Public Health.


Adam F.,Universiti Sains Malaysia | Appaturi J.N.,Universiti Sains Malaysia | Iqbal A.,International Islamic University Malaysia
Catalysis Today | Year: 2012

In this review article, we report the recent development and utilization of silica from rice husk (RH) for the immobilization of transition metals and organic moieties. Silicon precursor was obtained in the form of sodium silicate and as rice husk ash (RHA). Sodium silicate was obtained by direct silica extraction from rice husk via a solvent extraction method while rice husk ash was obtained by pyrolyzing the RH in the range of 500-800 °C for 5-6 h. Transition metals were immobilized into the silica matrix via the sol-gel technique while the organic moieties were incorporated using a grafting method. 3-(Chloropropyl)triethoxy-silane (CPTES) was used as a bridge to link the organic moieties to the silica matrix. All the catalysts exhibited good physical and catalytic potential in various reactions. © 2012 Elsevier B.V. All rights reserved.


Yee K.F.,Universiti Sains Malaysia | Wu J.C.S.,National Taiwan University | Lee K.T.,Universiti Sains Malaysia
Biomass and Bioenergy | Year: 2011

In this study, a simple and solvent-free method was used to prepare sulfated zirconia-alumina (SZA) catalyst. Its catalytic activity was subsequently investigated for the transesterification of Jatropha curcas L. oil to fatty acid methyl ester (FAME). The effects of catalyst preparation parameters on the yield of FAME were investigated using Design of Experiment (DOE). Results revealed that calcination temperature has a quadratic effect while calcination duration has a linear effect on the yield of FAME. Apart from that, interaction between both variables was also found to significantly affect the yield of FAME. At optimum condition; calcination temperature and calcination duration at 490 °C and 4 h, respectively, an optimum FAME yield of 78.2 wt% was obtained. Characterization with XRD, IR and BET were then used to verify the characteristic of SZA catalyst with those prepared using well established method and also to describe the catalyst characteristic with its activity. © 2011 Elsevier Ltd.


Hamad M.A.A.,Universiti Sains Malaysia | Hamad M.A.A.,Assiut University | Uddin M.J.,Universiti Sains Malaysia | Ismail A.I.M.,Universiti Sains Malaysia
International Journal of Heat and Mass Transfer | Year: 2012

The present paper investigates heat and mass transfer over a moving porous plate with hydrodynamic slip and thermal convective boundary conditions and concentration dependent diffusivity. The similarity representation of the system of partial differential equations of the problem is obtained through Lie group analysis. The resulting equations are solved numerically by Maple with Runge-Kutta-Fehlberg fourth-fifth order method. A representative set of results for the physical problem is displayed to illustrate the influence of parameters (velocity slip parameter, convective heat transfer parameter, concentration diffusivity parameter, Prandtl number and Schmidt number) on the dimensionless axial velocity, temperature and concentration field as well as the wall shear stress, the rate of heat transfer and the rate of mass transfer. The analytical solutions for velocity and temperature are obtained. Very good agreements are found between the analytical and numerical results of the present paper with published results. © 2011 Elsevier Ltd. All rights reserved.


Gui M.M.,University of Selangor | Chai S.-P.,University of Selangor | Xu B.-Q.,Tsinghua University | Mohamed A.R.,Universiti Sains Malaysia
Solar Energy Materials and Solar Cells | Year: 2014

This work demonstrates the synthesis of MWCNT/TiO2 core-shell nanocomposites and their application for photocatalytic reduction of CO 2 under visible light irradiation. MWCNT/TiO2 core-shell nanocomposites were obtained from a newly developed coating approach. UV-vis analysis revealed that the photoactivity of the nanocomposites in the visible light range was significantly enhanced with the absorption edge extended to the visible light region (>400 nm). The XRD and Raman analysis indicated that the TiO2 shell layer was composed of anatase TiO2 nanocrystallite prevailing grew along the (1 0 1) direction. The MWCNT/TiO 2 core-shell nanocomposites exhibited conversion of CO2 into methane in a continuous process under a low power visible light irradiation at atmospheric pressure. The highest methane yield of ca. 0.17 μmol/g-catalyst/h was recorded at the 6th hour of irradiation time. © 2013 Elsevier B.V. All rights reserved.


Hamad M.A.A.,Assiut University | Hamad M.A.A.,Universiti Sains Malaysia | Pop I.,Technical University of Cluj Napoca
Transport in Porous Media | Year: 2011

In this article, a similarity solution of the steady boundary layer flow near the stagnation-point flow on a permeable stretching sheet in a porous medium saturated with a nanofluid and in the presence of internal heat generation/absorption is theoretically studied. The governing partial differential equations with the corresponding boundary conditions are reduced to a set of ordinary differential equations with the appropriate boundary conditions via Lie-group analysis. Copper (Cu) with water as its base fluid has been considered and representative results have been obtained for the nanoparticle volume fraction parameter Φ in the range 0 ≤ Φ ≤ 0.2 with the Prandtl number of Pr = 6.8 for the water working fluid. Velocity and temperature profiles as well as the skin friction coefficient and the local Nusselt number are determined numerically. The influence of pertinent parameters such as nanofluid volume fraction parameter, the ratio of free stream velocity and stretching velocity parameter, the permeability parameter, suction/blowing parameter, and heat source/sink parameter on the flow and heat transfer characteristics is discussed. Comparisons with published results are also presented. It is shown that the inclusion of a nanoparticle into the base fluid of this problem is capable to change the flow pattern. © 2010 Springer Science+Business Media B.V.


Zyoud S.H.,Universiti Sains Malaysia | Al-Jabi S.W.,An Najah National University | Sweileh W.M.,An Najah National University | Morisky D.E.,University of California at Los Angeles
Health and Quality of Life Outcomes | Year: 2013

Background: The concepts of medication adherence and Treatment satisfactions are commonly used in clinical research for assessing pharmaceutical care and improving treatment outcomes. Generally, one would expect a positive relationship between the two concepts. The objectives of this study were to investigate the factors associated with adherence to antihypertensive therapy among hypertensive patients and to assess the relationship between antihypertensive medication adherence and treatment satisfaction.Methods: A cross-sectional study was conducted, adopting the Morisky eight-item Medication Adherence Scale (MMAS) for the assessment of medication adherence and using the Treatment Satisfaction Questionnaire for Medication (TSQM 1.4) for the assessment of treatment satisfaction. Descriptive and comparative statistics were used to describe socio-demographic and disease-related characteristics of the patients. All analyses were performed using SPSS v 15.0.Results: Four hundred and ten hypertensive patients were enrolled in the study. The mean age of participants was 58.38 ± 10.65 years; 52% were female and 36.8% had low antihypertensive medication adherence. There was a significant difference in the mean scores in the Effectiveness (p < 0.001), Convenience (p < 0.001), and Global Satisfaction (p < 0.001) domains, but not in the Side Effects (p = 0.466) domain among patients with different levels of adherence. After adjustment for covariates using multiple linear regression, global treatment satisfaction was still statistically significantly (p = 0.001) associated with medication adherence.Conclusions: Low treatment satisfaction may be an important barrier for achieving high rates of adherence to treatment. These study findings could be helpful in clinical practice, mainly in the early treatment of hypertensive patients, at a point where improving treatment satisfaction is still possible. © 2013 Zyoud et al.; licensee BioMed Central Ltd.


Azamathulla H.M.,Universiti Sains Malaysia | Wu F.-C.,National Taiwan University
Applied Soft Computing Journal | Year: 2011

This paper presents the support vector machine approach to predict the longitudinal dispersion coefficients in natural rivers. Collected published data from the literature for the dispersion coefficient for wide range of flow conditions are used for the development and testing of the proposed method. The proposed SVM approach produce satisfactory results with coefficient of determination = 0.9025 and root mean square error = 0.0078 compared to existing predictors for dispersion coefficient. © 2010 Elsevier B.V. All rights reserved.


Hassan N.K.,Universiti Sains Malaysia | Hashim M.R.,Universiti Sains Malaysia | Allam N.K.,American University in Cairo
Chemical Physics Letters | Year: 2012

ZnO nanotetrapod (ZnO-TP) photoanodes have been fabricated by a simple thermal evaporation method followed by characterization of their morphological, structural, optical and photoelectrochemical properties. The reaction time was found to be a critical factor in the synthesis of well-defined tetrapod nanostructures. The crystallinity of the grown tetrapods was investigated using X-ray diffraction as well as Raman spectroscopy. The photoluminescence (PL) spectra of the fabricated ZnO nanostructures showed two peaks; a near-band-edge (NBE) emission in the UV region and a broad deep-level emission (DLE) in the green emission region. Used as photoanodes to photoelectrochemically split water, the 90 min-treated ZnO-TP electrodes showed a photocurrent density of 0.4 mA/cm 2 under AM 1.5G illumination (100 mW/cm 2, 0.5 M Na 2SO 4), a significantly greater photocurrent than the bulk ZnO counterpart electrodes. The transient photocurrent measurements revealed exceptional stability of the as-fabricated ZnO-TPs. © 2012 Elsevier B.V. All rights reserved.


Abdul Ghani A.S.,University of Malaysia, Terengganu | Mat Isa N.A.,Universiti Sains Malaysia
Applied Soft Computing Journal | Year: 2015

The physical properties of water cause light-induced degradation of underwater images. Light rapidly loses intensity as it travels in water, depending on the color spectrum wavelength. Visible light is absorbed at the longest wavelength first. Red and blue are the most and least absorbed, respectively. Underwater images with low contrast are captured due to the degradation effects of light spectrum. Therefore, the valuable information from these images cannot be fully extracted for further processing. The current study proposes a new method to improve the contrast and reduce the noise of underwater images. The proposed method integrates the modification of image histogram into two main color models, Red-Green-Blue (RGB) and Hue-Saturation-Value (HSV). In the RGB color model, the histogram of the dominant color channel (i.e., blue channel) is stretched toward the lower level, with a maximum limit of 95%, whereas the inferior color channel (i.e., red channel) is stretched toward the upper level, with a minimum limit of 5%. The color channel between the dominant and inferior color channels (i.e., green channel) is stretched to both directions within the whole dynamic range. All stretching processes in the RGB color model are shaped to follow the Rayleigh distribution. The image is converted into the HSV color model, wherein the S and V components are modified within the limit of 1% from the minimum and maximum values. Qualitative analysis reveals that the proposed method significantly enhances the image contrast, reduces the blue-green effect, and minimizes under- and over-enhanced areas in the output image. For quantitative analysis, the test with 300 underwater images shows that the proposed method produces average mean square error (MSE) and peak signal to noise ratio (PSNR) of 76.76 and 31.13, respectively, which outperform six state-of-the-art methods. © 2014 Elsevier B.V. All rights reserved.


Hamad M.A.A.,Assiut University | Pop I.,Technical University of Cluj Napoca | Md Ismail A.I.,Universiti Sains Malaysia
Nonlinear Analysis: Real World Applications | Year: 2011

In this paper, we discuss similarity reductions for problems of magnetic field effects on free convection flow of a nanofluid past a semi-infinite vertical flat plate. The application of a one-parameter group reduces the number of independent variables by 1, and consequently the governing partial differential equation with the auxiliary conditions to an ordinary differential equation with the appropriate corresponding conditions. The differential equations obtained are solved numerically and the effects of the parameters governing the problem are discussed. Different kinds of nanoparticles were tested. © 2010 Elsevier Ltd. All rights reserved.


Murugaiyah V.,Universiti Sains Malaysia | Mattson M.P.,U.S. National Institute on Aging
Neurochemistry International | Year: 2015

The impact of dietary factors on brain health and vulnerability to disease is increasingly appreciated. The results of epidemiological studies, and intervention trials in animal models suggest that diets rich in phytochemicals can enhance neuroplasticity and resistance to neurodegeneration. Here we describe how interactions of plants and animals during their co-evolution, and resulting reciprocal adaptations, have shaped the remarkable characteristics of phytochemicals and their effects on the physiology of animal cells in general, and neurons in particular. Survival advantages were conferred upon plants capable of producing noxious bitter-tasting chemicals, and on animals able to tolerate the phytochemicals and consume the plants as an energy source. The remarkably diverse array of phytochemicals present in modern fruits, vegetables spices, tea and coffee may have arisen, in part, from the acquisition of adaptive cellular stress responses and detoxification enzymes in animals that enabled them to consume plants containing potentially toxic chemicals. Interestingly, some of the same adaptive stress response mechanisms that protect neurons against noxious phytochemicals are also activated by dietary energy restriction and vigorous physical exertion, two environmental challenges that shaped brain evolution. In this perspective article, we describe some of the signaling pathways relevant to cellular energy metabolism that are modulated by 'neurohormetic phytochemicals' (potentially toxic chemicals produced by plants that have beneficial effects on animals when consumed in moderate amounts). We highlight the cellular bioenergetics-related sirtuin, adenosine monophosphate activated protein kinase (AMPK), mammalian target of rapamycin (mTOR) and insulin-like growth factor 1 (IGF-1) pathways. The inclusion of dietary neurohormetic phytochemicals in an overall program for brain health that also includes exercise and energy restriction may find applications in the prevention and treatment of a range of neurological disorders. © Published by Elsevier Ltd.


Zerafat Angiz L. M.,Islamic Azad University | Emrouznejad A.,Aston University | Mustafa A.,Universiti Sains Malaysia
Expert Systems with Applications | Year: 2012

Data envelopment analysis (DEA) as introduced by Charnes, Cooper, and Rhodes (1978) is a linear programming technique that has widely been used to evaluate the relative efficiency of a set of homogenous decision making units (DMUs). In many real applications, the input-output variables cannot be precisely measured. This is particularly important in assessing efficiency of DMUs using DEA, since the efficiency score of inefficient DMUs are very sensitive to possible data errors. Hence, several approaches have been proposed to deal with imprecise data. Perhaps the most popular fuzzy DEA model is based on α-cut. One drawback of the α-cut approach is that it cannot include all information about uncertainty. This paper aims to introduce an alternative linear programming model that can include some uncertainty information from the intervals within the α-cut approach. We introduce the concept of "local α-level" to develop a multi-objective linear programming to measure the efficiency of DMUs under uncertainty. An example is given to illustrate the use of this method. © 2011 Elsevier Ltd. All rights reserved.


Shabannia R.,Iran University of Science and Technology | Hassan H.A.,Universiti Sains Malaysia
Electronic Materials Letters | Year: 2014

Vertically aligned ZnO nanorods were synthesized on a polyethylene naphthalate (PEN) substrate using a chemical bath deposition method at a low temperature. The structural and optical investigations revealed the high quality of the fabricated ZnO nanorods on flexible substrate. A metal-semiconductor-metal UV photodetector based on ZnO nanorods was fabricated on the PEN substrate. The optoelectronic characteristics of fabricated UV photodetector were studied in the dark and under 325 nm UV light illumination at -3 V and 3 V bias voltages. The responsivity and photosensitivity of the ZnO nanorod UV photodetector were 2.856 A/W and 1175% at 3 V bias voltage, respectively. Moreover, the response and the recovery times measured during the turn-on and turnoff of UV illumination were 1.2 s and 1.8 s, respectively. © 2014 The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht.


Mijarsh M.J.A.,Universiti Sains Malaysia | Mijarsh M.J.A.,Al Merghab University | Megat Johari M.A.,Universiti Sains Malaysia | Ahmad Z.A.,Universiti Sains Malaysia
Construction and Building Materials | Year: 2014

The aim of this study was to synthesize geopolymers using a large amount of treated palm oil fuel ash (TPOFA). The efficiency of the TPOFA (as the source material) in producing geopolymer products was enhanced via six factors which were optimized using the Taguchi method L25. The six factors were divided into two different components: (i) additive materials i.e. Ca(OH)2, silica fume (SF), Al2(OH)3, and (ii) alkaline activators; i.e. NaOH concentration (moles), Na-silicate: NaOH ratio, and alkali-activator:solid- material ratio. Each of these factors was examined on five levels in order to obtain the optimum mixture. A total of 25 mixtures were prepared in accordance to the L25 array proposed by the method. The performance of the specimens was evaluated by compressive strength tests. The results show that the optimum mixture consisted of 65 wt.% TPOFA and 35 wt.% additive materials which achieved a compressive strength of 47.27 ± 5.0 MPa after 7 days of curing. The properties of the optimized mixture were further analyzed via X-ray diffractography (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses. The results show that the main binding phases consist of aluminosilicate type gel "N-A-S-H" (Na2O-Al 2O3-SiO2-H2O) and calcium silicate hydrate (C-S-H) gels, formed simultaneously, within the TPOFA-based geopolymer mortar.©2013 Elsevier Ltd. All rights reserved.


Subramanian R.,Management and Science University | Asmawi M.Z.,Universiti Sains Malaysia | Sadikun A.,Universiti Sains Malaysia
Phytochemistry Reviews | Year: 2012

Andrographis paniculata (Burm.f) Nees is one of the most popular and important medicinal plant of the Orient, and South East Asia. It finds mention in various forms in Indian, Chinese, Malay, Thai, Unani, and Japanese systems of medicine. The plant exhibits anti-cancer, anti-inflammatory, anti-diabetic, antihypertensive, anti-venom, cholestatic, hepatoprotective, anti-thrombotic, anti-retroviral, anti-microbial, anti-pyretic, anti-malarial, anti-oxidant, immunomodulatory, and cardioprotective effects. The major active principles contributing to biological activity are diterpene lactones, but flavonoids, xanthones and caffeic acid derivatives also contribute to anti-oxidant, anti-proliferative, anti-atherosclerotic, and anti-malarial effects. As a result of its wide spectrum of pharmacological activity, almost impeccable safety profile, being a widely cultivated medicinal plant, we have collected and compiled various facets of this plant. Extensive datamining of the phytochemistry and pharmacology of Andrographis paniculata revealed more than 50 diterpene lactones, 30 flavonoids, 8 quinic acid derivatives, and 4 xanthones. This review contains information on around 80 isolated compounds, out of which more than half of the compounds have no reported pharmacological activity. Though there are some good reviews available on Andrographis paniculata, the authors of the earlier reviews focused on one or two aspects of the plant and none have attempted to integrate the available information on this plant. This provided us the much needed impetus, warranting a full-fledged and complete review on Andrographis paniculata, one of the most popular and important Oriental medicinal plant. © Springer Science+Business Media B.V. 2011.


Bhat R.,Universiti Sains Malaysia | Sridhar K.R.,Mangalore University
Journal of Food Composition and Analysis | Year: 2011

Electron spin resonance (ESR) spectroscopy was used to detect the free radicals that were naturally present in lotus seeds or that were formed after employing various food processing methods (e.g., irradiation, microwave roasting, pan frying, grinding or pounding) by placing small portions of lotus seed (seed coat and cotyledon) in KCl powder in ESR quartz tubes. Spectral analysis revealed the presence of an insignificant natural abundance of free radicals and showed a sharp and clear signal at g=2.002, more prominent in seed coat. Exposure to gamma radiation (0-30kGy, the recommended dose for quarantine purposes) resulted in a dose-dependent increase of signal intensity at g=2.002 with the seed coat exhibiting the presence of a weak triplet (aH=3mT) which can be used to authenticate irradiation treatments. Irradiated cotyledon at high doses (15 and 30kGy) revealed significant reduction in ESR signals, attributed to an increase of free radical scavengers. Common food processing practices like microwave roasting, flame heating, grinding or pounding also generated free radicals. It is envisaged that results of the present study might be valuable for health conscious consumers who are interested in the status of free radicals in foodstuffs subjected to traditional or modern food-processing techniques. © 2011 Elsevier Inc.


Obaid A.S.,Universiti Sains Malaysia | Obaid A.S.,University of Anbar | Hassan Z.,Universiti Sains Malaysia | Mahdi M.A.,Universiti Sains Malaysia | Bououdina M.,University of Bahrain
Solar Energy | Year: 2013

N-CdS/p-PbS heterojunction solar cells were prepared via microwave-assisted chemical bath deposition method. A cadmium sulfide (CdS) window layer (340nm thickness) was deposited on an indium tin oxide (ITO) glass. A lead sulfide (PbS) absorber layer (985-1380nm thickness) with different molar concentrations (0.02, 0.05, 0.075, and 0.1M) was then grown on ITO/CdS to fabricate a p-n junction. The effects of changing molar concentration of the absorber layer on structural and optical properties of the corresponding PbS thin films and solar cells were investigated. The optical band gap of the films decreased as the molarity increased. The photovoltaic properties (J-V characteristics, short circuit current, open circuit voltage, fill factor, and efficiency) of the CdS/PbS heterostructure cells were examined under 30mW/cm2 solar radiation. Interestingly, changing molar concentration improved the photovoltaic cells performances, the solar cell exhibited its highest efficiency (1.68%) at 0.1M molar concentration. © 2012 Elsevier Ltd.


Lean H.H.,Universiti Sains Malaysia | McAleer M.,Erasmus University Rotterdam | Wong W.-K.,Hong Kong Baptist University
Energy Economics | Year: 2010

This paper examines the market efficiency of oil spot and futures prices by using both mean-variance (MV) and stochastic dominance (SD) approaches. Based on the West Texas Intermediate crude oil data for the sample period 1989-2008, we find no evidence of any MV and SD relationships between oil spot and futures indices. This infers that there is no arbitrage opportunity between these two markets, spot and futures do not dominate one another, investors are indifferent to investing spot or futures, and the spot and futures oil markets are efficient and rational. The empirical findings are robust to each sub-period before and after the crises for different crises, and also to portfolio diversification. © 2010 Elsevier B.V.


Mehat N.M.,Kolej Kemahiran Tinggi MARA Balik Pulau | Mehat N.M.,Universiti Sains Malaysia | Kamaruddin S.,Universiti Sains Malaysia
Journal of Materials Processing Technology | Year: 2011

The large amount of plastic products presently produced necessitates recycling and reuse of these non-biodegradable materials. However, the degradation in the mechanical properties of products made from recycled plastic is a major drawback that limits their use. This study aims to improve the mechanical properties of products made from recycled plastic by utilizing the Taguchi optimization method, instead of coupling the products with additives. By adopting L9 Taguchi OA, products made from various compositions of virgin and recycled plastic are produced by injection moulding. Four controllable factors (i.e.; melt temperature, packing pressure, injection time, and packing time), each at three levels, are tested to determine the optimal combination of factors and levels in the manufacturing process. By determining the optimal combination of factors and levels, the appropriate blending ratio of virgin and recycled plastic can be evaluated from the mechanical performance exhibited by the compound. The effects of the optimal processing parameters and the addition of recycled plastic in various compositions on the mechanical properties and melt flow index of the produced parts are also investigated. The results reveal that the product made of 25% recycled polypropylene (PP) and 75% virgin PP exhibits a better flexural modulus compared to the virgin form. The same product exhibits a 3.4% decrease in flexural strength. The degradation in mechanical properties of products produced from recycled plastic can be improved by optimizing the influence processing parameters during the manufacturing process. © 2011 Elsevier B.V. All rights reserved.


Mabood F.,Universiti Sains Malaysia | Khan W.A.,University of Waterloo | Ismail A.I.M.,Universiti Sains Malaysia
Journal of Magnetism and Magnetic Materials | Year: 2015

The MHD laminar boundary layer flow with heat and mass transfer of an electrically conducting water-based nanofluid over a nonlinear stretching sheet with viscous dissipation effect is investigated numerically. This is the extension of the previous study on flow and heat transfer of a nanofluid over nonlinear stretching sheet (Rana and Bhargava, Commun. Nonlinear Sci. Numer. Simul. 17 (2012) 212-226). The governing equations are reduced to nonlinear ordinary differential equations using suitable similarity transformation. The effects of the governing parameters on dimensionless quantities like velocity, temperature, nanoparticle concentration, friction factor, local Nusselt, and Sherwood numbers are explored. It is found that the dimensionless velocity decreases and temperature increases with magnetic parameter, and the thermal boundary layer thickness increases with Brownian motion and thermophoresis parameters. © 2014 Elsevier B.V.


Akbar M.A.,Universiti Sains Malaysia | Ali N.H.M.,Universiti Sains Malaysia | Zayed E.M.E.,Zagazig University
Communications in Theoretical Physics | Year: 2012

In this article, we construct abundant exact traveling wave solutions involving free parameters to the generalized Bretherton equation via the improved (G′/G)-expansion method. The traveling wave solutions are presented in terms of the trigonometric, the hyperbolic, and rational functions. When the parameters take special values, the solitary waves are derived from the traveling waves. © 2012 Chinese Physical Society and IOP Publishing Ltd.


Ahmad N.S.,Universiti Sains Malaysia | Carrasco J.,University of Manchester | Heath W.P.,University of Manchester
IEEE Transactions on Automatic Control | Year: 2015

Many conditions have been found for the absolute stability of discrete-time Lur'e systems in the literature. It is advantageous to find convex searches via LMIs where possible. In this technical note, we construct two less conservative LMI conditions for discrete-time systems with slope-restricted nonlinearities. The first condition is derived via Lyapunov theory while the second is derived via the theory of integral quadratic constraints (IQCs) and noncausal Zames-Falb multipliers. Both conditions are related to the Jury-Lee criterion most appropriate for systems with such nonlinearities, and the second generalizes it. Numerical examples demonstrate a significant reduction in conservatism over competing approaches. © 2015 IEEE.


Chellvarajoo S.,Universiti Sains Malaysia | Abdullah M.Z.,Universiti Sains Malaysia | Samsudin Z.,Global Operation Service
Materials and Design | Year: 2015

This study investigates the effects of the addition of Fe2NiO4 nanoparticles into a SAC-305 lead-free solder paste. Iron, nickel, and oxide nano-elements were mixed with Pb-free solder alloying elements to produce a new form of nanocomposite solder paste, which can be a promising material in electronic packaging. The SAC-305 was mechanically added with 0.5, 1.5, and 2.5wt.% of Fe2NiO4 nanoparticles. The migration of nanoparticles in the nanocomposite solder paste to the outermost surface was clarified using the copper 'sandwich' method, which was performed after the reflow soldering process. Varying amounts of nanoparticles in the SAC-305 affected the IMC thickness and mechanical properties of the nanocomposite solder paste. The IMC thickness was reduced by 29.15%, 42.37%, and 59.00% after adding 0.5, 1.5, and 2.5wt.% of Fe2NiO4 nanoparticles in the SAC-305, respectively. However, via nanoindentation method, the hardness of the nanocomposite solder was improved by 44.07% and 56.82% after adding 0.5 and 1.5wt.% of Fe2NiO4 nanoparticles, respectively. If the addition of Fe2NiO4 nanoparticle exceeded 1.5wt.%, the hardness increased infinitely. © 2014 Elsevier Ltd.


Nuhu A.A.,King Fahd University of Petroleum and Minerals | Basheer C.,King Fahd University of Petroleum and Minerals | Saad B.,Universiti Sains Malaysia
Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences | Year: 2011

Liquid phase microextraction (LPME), especially hollow fiber liquid-phase microextraction (HF-LPME), and dispersive liquid-liquid microextraction (DLLME) offer high enrichments of target analytes in a single step. The analytical usefulness of these techniques is significantly enhanced by coupling them with suitable derivatization methods. Due to their simplicity, diverse bioanalytical applications have recently been reported. This review focuses on the recent developments of the combined LPME (mainly HF-LPME and single drop microextraction (SDME)) and DLLME techniques with derivatization for the analysis of biological samples. A broad range of sample matrices such as urine, blood, plasma and human hair samples with various derivatization methods for polar or ionizable organic compounds will be considered. These techniques can also be extended to the determination of trace metal ions, such as the heavy metal ions (Hg, Pb, and Co) and Se. Future trends of the techniques will also be discussed. © 2011 Elsevier B.V.


Yusuf M.O.,Universiti Sains Malaysia | Yusuf M.O.,King Fahd University of Petroleum and Minerals | Megat Johari M.A.,Universiti Sains Malaysia | Ahmad Z.A.,Universiti Sains Malaysia | Maslehuddin M.,King Fahd University of Petroleum and Minerals
Construction and Building Materials | Year: 2014

In this study, combinations of ultrafine palm oil fuel ash (UPOFA) and ground blast furnace slag (GBFS) have been used to study the compressive strength and microstructure of the alkali-activated GBFS-UPOFA (AAGU) binary blended binder paste. GBFS (G) was added in varying percentages to alkaline activated UPOFA (AAU) such that the ratio of G/U + G varied from 0 to 0.3 at interval of 0.05. Sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) with a final silicate modulus (Ms = SiO2/Na 2O) of 1.58 were used as activators. Pozzolanic materials (G + U), activators, and free water were combined by weight ratios as: 1/0.35/0.02. A 28-day compressive strength of 44 MPa was achieved for G/U + G of 0.2 cured for 24 h at 60 C. Finally, characterization was done using X-ray diffraction, SEM and FTIR and the analyses revealed that GBFS contributes significantly to the mechanical strength by pore filling effects, and the formation of additional calcium (aluminate) silicate hydrate (C(A)SH). © 2013 Elsevier Ltd. All rights reserved.


Yusuf M.O.,Universiti Sains Malaysia | Yusuf M.O.,King Fahd University of Petroleum and Minerals | Megat Johari M.A.,Universiti Sains Malaysia | Ahmad Z.A.,Universiti Sains Malaysia | Maslehuddin M.,King Fahd University of Petroleum and Minerals
Materials and Design | Year: 2014

The two locally available pozzolanic solid wastes (PMs) - ultrafine palm oil fuel ash (UPOFA) and ground blast furnace slag (GBFS) - have been used as base materials to develop high alkaline activated strength concrete. The samples were prepared with combined aggregate modulus of 3.66 and at constant GBFS/PM that varied from 0 to 0.3. The combined alkaline activators (CAA) (Na2SiO3 and NaOH) to PMs ratios (CAA/PMs), temperature and curing durations also varied as 0.45-0.55, 25-90°C, and 6-24h, respectively. The findings revealed that the strength at 3-day and 28-day were 69.13 and 71.2MPa, respectively and the respective optimum GBFS/PM, CAA/PM, temperature and curing duration are 0.2, 0.5, 60°C and 24h. GBFS was found to contribute to the soluble Ca, heterogeneity, and amorphousity of the product. This eventually facilitated the formation of suspected calcium-silicate-hydrate and the geopolymer products of Ca/Na-aluminosilicate-hydrate (C/NASH) that enhanced the compressive-strength results. © 2013 Elsevier Ltd.


Mydin M.A.O.,Universiti Sains Malaysia | Wang Y.C.,University of Manchester
Construction and Building Materials | Year: 2012

This paper reports the results of an experimental and analytical study to investigate the mechanical properties of unstressed foamed concrete exposed to high temperatures. Two densities of foamed concrete, 650 and 1000 kg/m 3, were made and tested with additional tests being performed on densities of 800, 1200 and 1400 kg/m3 for additional data. The experimental results consistently demonstrated that the loss in stiffness for foamed concrete at elevated temperatures occurs predominantly after about 90 °C, regardless of density as water expands and evaporates from the porous body. From a comparison of the experimental results of this research with a number of predictive models for normal strength concrete, this research has found that the mechanical properties of foamed concrete can be predicted using the mechanical property models for normal weight concrete given that the mechanical properties of foamed concrete come from Portland Cement CEM1. © 2011 Elsevier Ltd. All rights reserved.


Grant
Agency: Cordis | Branch: FP7 | Program: CP-FP-SICA | Phase: SSH.2012.4.1-2 | Award Amount: 3.05M | Year: 2012

The project SEATIDE brings together Southeast Asian (SEA) and European researchers with two objectives: research and network development. Research. Using locally focused field study methodologies, our experience of research on integration frameworks in Southeast Asia shows that historical and contemporary integrative processes include some groups and exclude others. Exclusion of communities presents risks to human development and security, even of framework disintegration. This understanding directs our research question: in processes of integration, who is excluded? We address it in thematic work packages with relevant qualitative/quantitative case studies guided by a common analytical framework focused on four key issues: diversity, prosperity, knowledge and security. Attention to SEAs sub-regions and globalisation/transnational issues defines our approach. Structuring the European Research Area (ERA). On the basis of existing structures the unique EFEO network of 10 field centres in SEA, plus ECAF, EUROSEAS, ASEF we work for the development of effective, integrated networks of EU-SEA research, embracing Western European and ASEAN-founder countries alongside Eastern/Southern Europe and post-communist SEA nations. Broad dissemination of results is essential to the projects success, through conferences, publications, press coverage and policy briefs. Our recent and innovative research serves to improve the dialogue initiated in the EFEOs FP7 project IDEAS between social scientists and policymakers.


Lok Y.Y.,Universiti Sains Malaysia | Pop I.,Technical University of Cluj Napoca
Physics of Fluids | Year: 2011

In this paper, the steady axisymmetric stagnation point flow of a viscous and incompressible fluid over a shrinking circular cylinder with mass transfer (suction) is studied. The flow is induced by a cylinder shrinking with a linear velocity distribution from the stagnation line. The fluid flow solution is an exact solution of the Navier-Stokes equation, which is reduced to a nonlinear ordinary differential equation. This equation is solved numerically for some values of the governing parameters that involves a Reynolds number R, a shrinking parameter λa suction parameter γ. The effects of these governing parameters on the velocity and temperature profiles, skin friction coefficient, Nusselt number, as well as the distributions of the streamlines are investigated. The obtained results for the case of fixed cylinder are compared with those from the open literature and it is shown that they are in excellent agreement. The solutions are non-unique for some values of λ (<0). The streamlines show that the flow structures become complicated due to the shrinking and suction effects. © 2011 American Institute of Physics.


Mohajeri L.,Universiti Sains Malaysia | Aziz H.A.,Universiti Sains Malaysia | Isa M.H.,Petronas University of Technology | Zahed M.A.,Universiti Sains Malaysia
Bioresource Technology | Year: 2010

This work studied the bioremediation of weathered crude oil (WCO) in coastal sediment samples using central composite face centered design (CCFD) under response surface methodology (RSM). Initial oil concentration, biomass, nitrogen and phosphorus concentrations were used as independent variables (factors) and oil removal as dependent variable (response) in a 60 days trial. A statistically significant model for WCO removal was obtained. The coefficient of determination (R2 = 0.9732) and probability value (P < 0.0001) demonstrated significance for the regression model. Numerical optimization based on desirability function were carried out for initial oil concentration of 2, 16 and 30 g per kg sediment and 83.13, 78.06 and 69.92 per cent removal were observed respectively, compare to 77.13, 74.17 and 69.87 per cent removal for un-optimized results. © 2009 Elsevier Ltd. All rights reserved.


Balaji S.,Thiagarajar College of Engineering | Vasuki R.,Thiagarajar College of Engineering | Mutharasu D.,Universiti Sains Malaysia
Journal of Alloys and Compounds | Year: 2013

The SnO2/NiFe2O4 nanocomposite samples with varying concentration of SnO2 such as 5 wt.% and 10 wt.% were synthesized via urea assisted combustion synthesis. The kinetics of the combustion reactions were studied using thermo gravimetry analysis and from which the compound formation temperature of all the samples were observed to be below 400 °C. From the morphological analysis the grain size of NiFe 2O4, 5 wt.% SnO2/NiFe2O4 and 10 wt.% SnO2/NiFe2O4 samples were observed to be around 1.7, 2.3 and 3.5 μm. The chrono potentiometry analyses of the samples were performed against lithium metal electrode. The capacity retention was found to be higher for composite with 10 wt.% SnO2. The discharge capacity of 10 wt.% SnO2 sample with respect to Li metal and LiMn2O4 electrode was observed to be around 980 mA h/g and 138 mA h/g respectively. © 2012 Elsevier B.V. All rights reserved.


Rohni A.M.,Northern University of Malaysia | Ahmad S.,Universiti Sains Malaysia | Pop I.,Technical University of Cluj Napoca
International Journal of Heat and Mass Transfer | Year: 2012

The unsteady flow over a continuously shrinking surface with wall mass suction in a water based nanofluid containing different type of nanoparticles: Cu, Al 2O 3 and TiO 2 is numerically studied. Similarity equations are obtained through the application of similarity transformation techniques. The shooting method is used to solve the similarity equations for different values of the wall mass suction, the unsteadiness and the nanoparticle volume fraction parameters. The results of skin friction coefficient f″(0) and heat transfer rate -θ′(0) are presented in tables and graphs. It is found that dual solution exists for a certain range of wall mass suction s, volume fraction and unsteadiness parameters A. The results of velocity and temperature profiles are also presented. It is seen that two values of boundary layer thickness η ∞ are obtained, which gives two different velocity and temperature profiles that satisfy the boundary conditions. It is also found that the nanoparticle volume fraction parameter and types of nanofluid play an important role to significantly determine the flow behaviour. © 2011 Elsevier Ltd. All rights reserved.


Kole P.L.,Queen's University of Belfast | Venkatesh G.,Universiti Sains Malaysia | Kotecha J.,Torrent Pharmaceuticals Ltd | Sheshala R.,Universiti Sains Malaysia
Biomedical Chromatography | Year: 2011

This paper reviews the recent developments in bioanalysis sample preparation techniques and gives an update on basic principles, theory, applications and possibilities for automation, and a comparative discussion on the advantages and limitation of each technique. Conventional liquid-liquid extraction (LLE), protein precipitation (PP) and solid-phase extraction (SPE) techniques are now been considered as methods of the past. The last decade has witnessed a rapid development of novel sample preparation techniques in bioanalysis. Developments in SPE techniques such as selective sorbents and in the overall approach to SPE, such as hybrid SPE and molecularly imprinted polymer SPE, have been addressed. Considerable literature has been published in the area of solid-phase micro-extraction and its different versions, e.g. stir bar sorptive extraction, and their application in the development of selective and sensitive bioanalytical methods. Techniques such as dispersive solid-phase extraction, disposable pipette extraction and micro-extraction by packed sorbent offer a variety of extraction phases and provide unique advantages to bioanalytical methods. On-line SPE utilizing column-switching techniques is rapidly gaining acceptance in bioanalytical applications. PP sample preparation techniques such as PP filter plates/tubes offer many advantages like removal of phospholipids and proteins in plasma/serum. Newer approaches to conventional LLE techniques (salting-out LLE) are also covered in this review article. © 2010 John Wiley & Sons, Ltd.


Ahmad S.,Universiti Sains Malaysia | Pop I.,Technical University of Cluj Napoca
International Communications in Heat and Mass Transfer | Year: 2010

The steady mixed convection boundary layer flow past a vertical flat plate embedded in a porous medium filled with nanofluids is studied using different types of nanoparticles as Cu (cuprom), Al2O3 (aluminium) and TiO2 (titanium). The model used for the nanofluid is the one which incorporates only the nanoparticle volume fraction parameter. The basic partial equations are reduced to an ordinary differential equation which is solved numerically for some values of the volume fraction and mixed convection parameters. It is shown that the solution has two branches in a certain range of the parameters. The effects of these parameters on the velocity distribution are presented graphically. © 2010 Elsevier Ltd.


Ahmad S.,Universiti Sains Malaysia | Rohni A.M.,Northern University of Malaysia | Pop I.,Technical University of Cluj Napoca
Acta Mechanica | Year: 2011

The classical problems of forced convection boundary layer flow and heat transfer past a semi-infinite static flat plate (Blasius problem) and past a moving semi-infinite flat plate (Sakiadis problem) using nanofluids are theoretically studied. The similarity equations are solved numerically for three types of metallic or nonmetallic nanoparticles such as copper (Cu), alumina (Al2O3), and titania (TiO2) in the base fluid of water with the Prandtl number Pr = 6.2 to investigate the effect of the solid volume fraction parameter φ of the nanofluids. Also, the case of conventional or regular fluid (φ = 0) with Pr = 0.7 is considered for comparison with known results from the open literature. The comparison shows excellent agreement. The skin friction coefficient, Nusselt number, and the velocity and temperature profiles are presented and discussed in detail. It is found that the solid volume fraction affects the fluid flow and heat transfer characteristics. © 2010 Springer-Verlag.


Shuit S.H.,Universiti Sains Malaysia | Lee K.T.,Universiti Sains Malaysia | Kamaruddin A.H.,Universiti Sains Malaysia | Yusup S.,Petronas University of Technology
Environmental Science and Technology | Year: 2010

Biodiesel from Jatropha curcas L. seed is conventionally produced via a two-step method: extraction of oil and subsequent esterification/ transesterification to fatty acid methyl esters (FAME), commonly known as biodiesel. Contrarily, in this study, a single step in situ extraction, esterification and transesterification (collectively known as reactive extraction) of J. curcas L. seed to biodiesel, was investigated and optimized. Design of experiments (DOE) was used to study the effect of various process parameters on the yield of FAME. The process parameters studied include reaction temperature (30-60 °C), methanol to seed ratio (5-20 mL/g), catalyst loading (5-30 wt %), and reaction time (1-24 h). The optimum reaction condition was then obtained by using response surface methodology (RSM) coupled with central composite design (CCD). Results showed that an optimum biodiesel yield of 98.1% can be obtained under the following reaction conditions: reaction temperature of 60 °C, methanol to seed ratio of 10.5 mL/g, 21.8 wt % of H2SO4, and reaction period of 10 h. © 2010 American Chemical Society.


Rashidi N.A.,Petronas University of Technology | Yusup S.,Petronas University of Technology | Hameed B.H.,Universiti Sains Malaysia
Energy | Year: 2013

CO2(Carbon dioxide) emissions are one of the greenhouse gases that cause global warming. The power generation industry is one of the main emitters of CO2, and the emissions are expected to increase in the coming years as there seems to be no abatement in the consumption of fossil fuels for the production of electricity. Thus, there is a need for CO2 adsorption technologies to mitigate the emissions. However, there are several disadvantages associated with the current adsorption technologies. One of the issues is corrosion and the need for specialized equipment. Therefore, alternative and more sustainable materials are sought after to improve the viability of the adsorption technology. In this study, several types of agricultural wastes were used as activated carbon precursors for CO2 adsorption process in a TGA (thermogravimetric analyser). The adsorption was also modelled through a pseudo-first order and second order model, Elovich's kinetic model, and an intra-particle diffusion model. From the correlation coefficient, it was found that pseudo-second order model was well-fitted with the kinetic data. In addition, activation energy below than 42kJ/mol confirmed that the physisorption process occurred. © 2013 Elsevier Ltd.


Khoo M.B.C.,Universiti Sains Malaysia | Teoh W.L.,Universiti Sains Malaysia | Castagliola P.,University of Nantes | Lee M.H.,University of Technology Malaysia
International Journal of Production Economics | Year: 2013

The double sampling (DS) X̄ chart detects small and moderate mean shifts quickly. Furthermore, this chart can reduce the sample size. The DS X̄ chart is usually investigated assuming that the process parameters are known. Nevertheless, the process parameters are usually unknown and are estimated from an in-control Phase-I dataset. This paper (i) evaluates the performances of the DS X̄ chart when process parameters are estimated by means of a new proposed theoretical method, (ii) shows that performances with estimated parameters are different from that with known parameters, and (iii) proposes three optimal design procedures: the first design minimizes the out-of-control average run length, the second design minimizes the in-control average sample size and the third design minimizes the average extra quadratic loss, by considering the number of Phase-I samples in these three designs. Additionally, for ease of implementation, this paper provides the new optimal parameters specially computed for the DS X̄ chart with estimated parameters, based on the number of Phase-I samples used in practice. These findings will lead to a more economically feasible process monitoring situation, especially when the process parameters are unknown. © 2013 Elsevier B.V. All rights reserved.


Karim S.A.A.,Petronas University of Technology | Pang K.V.,Universiti Sains Malaysia
AIP Conference Proceedings | Year: 2012

This paper proposed GC1 rational quartic spline (quartic numerator and linear denominator) with two parameters to preserve the shape of the monotone data. Simple data dependent constraints will be derived on one of the parameters while the other is free to modify and refine the resultant shape of the data. Both parameters are independent to each other. The method under consideration here, avoid the modification of the derivative when the sufficient condition for the monotonicity are violated as can be noticed in the original construction of C1 rational quartic spline with linear denominator. Numerical comparison between the proposed scheme and C1 rational quartic spline will be given. © 2012 American Institute of Physics.


Tay K.M.,University Malaysia Sarawak | Lim C.P.,Universiti Sains Malaysia
International Journal of Uncertainty, Fuzziness and Knowlege-Based Systems | Year: 2011

An important and difficult issue in designing a Fuzzy Inference System (FIS) is the specification of fuzzy sets and fuzzy rules. In this paper, two useful qualitative properties of the FIS model, i.e., the monotonicity and sub-additivity properties, are studied. The monotonic sufficient conditions of the FIS model with Gaussian membership functions are further analyzed. The aim is to incorporate the sufficient conditions into the FIS modeling process, which serves as a simple (which can be easily understood by domain users), easy-to-use (which can be easily applied to or can be a part of the FIS model), and yet reliable (which has a sound mathematical foundation) method to preserve the monotonicity property of the FIS model. Another aim of this paper is to demonstrate how these additional qualitative information can be exploited and extended to be part of the FIS designing procedure (i.e., for fuzzy sets and fuzzy rules design) via the sufficient conditions (which act as a set of useful governing equations for designing the FIS model). The proposed approach is able to avoid the "trial and error" procedure in obtaining a monotonic FIS model. To assess the applicability of the proposed approach, two practical problems are examined. The first is an FIS-based model for water level control, while the second is an FIS-based Risk Priority Number (RPN) model in Failure Mode and Effect Analysis (FMEA). To further illustrate the importance of the sufficient conditions as the governing equations, an analysis on the consequences of violating the sufficient conditions of the FIS-based RPN model is presented. © 2011 World Scientific Publishing Company.


Uddin M.J.,Universiti Sains Malaysia | Uddin M.J.,Bangladesh American International University | Khan W.A.,National University of Sciences and Technology | Ismail A.I.,Universiti Sains Malaysia
PLoS ONE | Year: 2012

Steady two dimensional MHD laminar free convective boundary layer flows of an electrically conducting Newtonian nanofluid over a solid stationary vertical plate in a quiescent fluid taking into account the Newtonian heating boundary condition is investigated numerically. A magnetic field can be used to control the motion of an electrically conducting fluid in micro/nano scale systems used for transportation of fluid. The transport equations along with the boundary conditions are first converted into dimensionless form and then using linear group of transformations, the similarity governing equations are developed. The transformed equations are solved numerically using the Runge-Kutta-Fehlberg fourth-fifth order method with shooting technique. The effects of different controlling parameters, namely, Lewis number, Prandtl number, buoyancy ratio, thermophoresis, Brownian motion, magnetic field and Newtonian heating on the flow and heat transfer are investigated. The numerical results for the dimensionless axial velocity, temperature and nanoparticle volume fraction as well as the reduced Nusselt and Sherwood number have been presented graphically and discussed. It is found that the rate of heat and mass transfer increase as Newtonian heating parameter increases. The dimensionless velocity and temperature distributions increase with the increase of Newtonian heating parameter. The results of the reduced heat transfer rate is compared for convective heating boundary condition and found an excellent agreement. © 2012 Uddin et al.


Guven A.,University of Gaziantep | Azamathulla H.Md.,Universiti Sains Malaysia
Water Science and Technology | Year: 2012

During the last two decades, researchers have noticed that the use of soft computing techniques as an alternative to conventional statistical methods based on controlled laboratory or field data, gave significantly better results. Gene-expression programming (GEP), which is an extension to genetic programming (GP), has nowadays attracted the attention of researchers in prediction of hydraulic data. This study presents GEP as an alternative tool in the prediction of scour downstream of a flip-bucket spillway. Actual field measurements were used to develop GEP models. The proposed GEP models are compared with the earlier conventional GP results of others (Azamathulla et al. 2008b; RMSE = 2.347, δ = 0.377, R = 0.842) and those of commonly used regression-based formulae. The predictions of GEP models were observed to be in strictly good agreement with measured ones, and quite a bit better than conventional GP and the regression-based formulae. The results are tabulated in terms of statistical error measures (GEP1; RMSE = 1.596, δ = 0.109, R = 0.917) and illustrated via scatter plots. © IWA Publishing 2012.


Uddin Md.J.,Bangladesh American International University | Beg O.A.,Propulsion Research | Ismail A.I.,Universiti Sains Malaysia
Journal of Thermophysics and Heat Transfer | Year: 2015

Steady two-dimensional laminar mixed convective boundary-layer slip nanofluid flow in a Darcian porous medium due to a stretching/shrinking sheet is studied theoretically and numerically.Athermal radiative effect is incorporated in the model. The governing transport, partial differential equations, along with the boundary conditions, are transformed into a dimensionless form and then, via a linear group of transformation, a system of coupled similarity differential equations is derived. The transformed equations are solved numerically using the Runge-Kutta-Fehlberg fourth-fifth-order numerical quadrature method from Maple symbolic software. The effects of the controlling parameters (namely, stretching/shrinking, velocity slip, thermal slip, mass slip, Darcy number, radiation conduction, buoyancy ratio parameter, and Lewis number) on the dimensionless velocity, temperature, nanoparticle volume fraction, velocity gradient, temperature gradient, and nanoparticle volume fraction gradient are shown in graphical form and interpreted in detail. Comparisons with published works are carried out and are found to be in excellent agreement. The current study is relevant to high-temperature nanomaterials processing operations. Copyright © 2014 by the American Institute of Aeronautics and Astronautics, Inc.


Tay K.M.,University Malaysia Sarawak | Lim C.P.,Universiti Sains Malaysia
IEEE International Conference on Fuzzy Systems | Year: 2011

In this paper, an Evolutionary-based Similarity Reasoning (ESR) scheme for preserving the monotonicity property of the multi-input Fuzzy Inference System (FIS) is proposed. Similarity reasoning (SR) is a useful solution for undertaking the incomplete rule base problem in FIS modeling. However, SR may not be a direct solution to designing monotonic multi-input FIS models, owing to the difficulty in getting a set of monotonically-ordered conclusions. The proposed ESR scheme, which is a synthesis of evolutionary computing, sufficient conditions, and SR, provides a useful solution to modeling and preserving the monotonicity property of multi-input FIS models. A case study on Failure Mode and Effect Analysis (FMEA) is used to demonstrate the effectiveness of the proposed ESR scheme in undertaking real world problems that require the monotonicity property of FIS models. © 2011 IEEE.


Tay K.M.,University Malaysia Sarawak | Lim C.P.,Universiti Sains Malaysia
Journal of Intelligent and Fuzzy Systems | Year: 2010

Traditional Failure Mode and Effect Analysis (FMEA) adopts the Risk Priority Number (RPN) ranking model to evaluate failure risks, to rank failures, as well as to prioritize actions. Although this approach is simple, it suffers from several shortcomings. In this paper, we investigate a number of fuzzy inference techniques for determining the RPN scores, in an attempt to overcome the weaknesses associated with the traditional RPN model. The main objective is to examine the possibility of using fuzzy rule interpolation and reduction techniques to design new fuzzy RPN models. The performance of the fuzzy RPN models is evaluated using a real-world case study pertaining to the test handler process in a semiconductor manufacturing plant. The FMEA procedure for the test handler is performed, and a fuzzy RPN model is developed. In addition, improvement to the fuzzy RPN model is proposed by refining the weights of the fuzzy production rules, hence a new weighted fuzzy RPN model. The ability of the weighted fuzzy RPN model in failure risk evaluation with a reduced rule base is also demonstrated. © 2010-IOS Press and the authors. All rights reserved.


Tay K.M.,University Malaysia Sarawak | Lim C.P.,Universiti Sains Malaysia
IEEE International Conference on Fuzzy Systems | Year: 2011

In this paper, two issues relating to modeling of a monotonicity-preserving Fuzzy Inference System (FIS) are examined. The first is on designing or tuning of Gaussian Membership Functions (MFs) for a monotonic FIS. Designing Gaussian MFs for an FIS is difficult because of its spreading and curvature characteristics. In this study, the sufficient conditions are exploited, and the procedure of designing Gaussian MFs is formulated as a constrained optimization problem. The second issue is on the testing procedure for a monotonic FIS. As such, a testing procedure for a monotonic FIS model is proposed. Applicability of the proposed approach is demonstrated with a real world industrial application, i.e., Failure Mode and Effect Analysis. The results obtained are analysis and discussed. The outcomes show that the proposed approach is useful in designing a monotonicity-preserving FIS model. © 2011 IEEE.


Behzadian M.,University of Tehran | Khanmohammadi Otaghsara S.,Islamic Azad University at Firoozkooh | Yazdani M.,Islamic Azad University at Firoozkooh | Ignatius J.,Universiti Sains Malaysia
Expert Systems with Applications | Year: 2012

Multi-Criteria Decision Aid (MCDA) or Multi-Criteria Decision Making (MCDM) methods have received much attention from researchers and practitioners in evaluating, assessing and ranking alternatives across diverse industries. Among numerous MCDA/MCDM methods developed to solve real-world decision problems, the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) continues to work satisfactorily across different application areas. In this paper, we conduct a state-of-the-art literature survey to taxonomize the research on TOPSIS applications and methodologies. The classification scheme for this review contains 266 scholarly papers from 103 journals since the year 2000, separated into nine application areas: (1) Supply Chain Management and Logistics, (2) Design, Engineering and Manufacturing Systems, (3) Business and Marketing Management, (4) Health, Safety and Environment Management, (5) Human Resources Management, (6) Energy Management, (7) Chemical Engineering, (8) Water Resources Management and (9) Other topics. Scholarly papers in the TOPSIS discipline are further interpreted based on (1) publication year, (2) publication journal, (3) authors' nationality and (4) other methods combined or compared with TOPSIS. We end our review paper with recommendations for future research in TOPSIS decision-making that is both forward-looking and practically oriented. This paper provides useful insights into the TOPSIS method and suggests a framework for future attempts in this area for academic researchers and practitioners. © 2012 Elsevier Ltd. All rights reserved.


Azamathulla H.M.,Universiti Sains Malaysia | Guven A.,University of Gaziantep | Demir Y.K.,University of Gaziantep
Ocean Engineering | Year: 2011

Genetic programming (GP) has nowadays attracted the attention of researchers in the prediction of hydraulic data. This study presents Linear Genetic Programming (LGP), which is an extension to GP, as an alternative tool in the prediction of scour depth below a pipeline. The data sets of laboratory measurements were collected from published literature and were used to develop LGP models. The proposed LGP models were compared with adaptive neuro-fuzzy inference system (ANFIS) model results. The predictions of LGP were observed to be in good agreement with measured data, and quite better than ANFIS and regression-based equation of scour depth at submerged pipeline. © 2011 Elsevier Ltd.


Leo C.P.,Universiti Sains Malaysia | Cathie Lee W.P.,University of Selangor | Ahmad A.L.,Universiti Sains Malaysia | Mohammad A.W.,National University of Malaysia
Separation and Purification Technology | Year: 2012

Polysulfone (PSf) membranes are undesirably hydrophobic, thus they are susceptible to the fouling by most organic components including fatty acids. In this work, ZnO nanoparticles were blended into PSf membranes to improve its properties in reduction of fouling by oleic acid. The casting solution was prepared by dispersing 1-4 wt.% of ZnO nanoparticles (21-23 nm), 1 wt.% of PVA and PSf into 1-methyl-2-pyrrolidinone at 75 °C, with a stirring speed of 400 rpm. The weight ratio of polymer to solvent is maintained at 1:4.84. The composite membranes were then prepared using phase inversion method. The mean pore size of the composite membranes is slightly larger than the mean pore size of pure PSf membrane. However, the water contact angle greatly reduces from 85° to 63° when 2 wt.% of ZnO is added into Pf-2 membranes. Thermal stability of PSf membranes has significantly improved with the addition of ZnO. Although absorption peaks of ZnO are absent in FT-IR patterns, EDX analysis shows that ZnO nanoparticles are well distributed in the dense layer of Pf-2 membrane. Hence, Pf-2 membranes show the highest permeability and the least fouling by oleic acid. © 2012 Elsevier B.V. All rights reserved.


Oladoja N.A.,Adekunle Ajasin University | Ahmad A.L.,Universiti Sains Malaysia
Separation and Purification Technology | Year: 2013

The synergies of binary metal oxides, habitual in natural system, in sequestrating metal ions were the premise on the synthesis of binary alkali earth and transition metal oxides (ATM) for possible environmental remediation. Gastropod shell (GS) was used as a precursor for alkali earth metal generation in the perspective of wastes recycling and cost minimization in material synthesis. ATM of different combination ratios of Ca: Fe, were synthesized and characterized (XRD, SEM, EDAX, TGA and PZC) and the potential for Cr(VI) attenuation in aqua system was appraised. The Langmuir sorption capacities (mg/g) of the ATM (112.36-117.65) were higher than that of the respective metal ion constituents (101.01-105.26). Kinetic modeling showed that the pseudo second order gave the best description of the process. pH had nominal effect on the extent of Cr(VI) sorption while the magnitude of Cr(VI) sorbed reduced with increase in molar concentrations of anions and ionic strength. The spent ATM stability, determined via the toxicity characteristic leaching procedure (TCLP), was higher in acidic medium than the alkaline medium. SEM and EDAX elucidation, confirmed the presence of Cr(VI) on the sorbent while the formation of complexes of Cr ions with metal-O functional groups was confirmed via FTIR analysis. © 2013 Elsevier B.V. All rights reserved.


Goswami S.,Bengal Engg And Science University | Manna A.,Bengal Engg And Science University | Paul S.,Bengal Engg And Science University | Kheng Quah C.,Universiti Sains Malaysia | And 2 more authors.
Chemical Communications | Year: 2013

We have designed a chemodosimeter DPNO (weak fluorescence) which can be oxidized to HPNO (strong blue fluorescence) by OCl- with high selectivity and sensitivity in a ratiometric approach with a noticeably lower detection limit. The sensor could be useful for the detection of hypochlorites in tap water. © 2013 The Royal Society of Chemistry.


Mustafa F.H.,Hawler Medical University | Jaafar M.S.,Universiti Sains Malaysia
Indian Journal of Physics | Year: 2013

The determination of the penetration depth of laser light with different sources wavelengths into human skin is one of the preconditions of improving the photodynamic therapy (PDT) procedure for skin diseases. This research is planned to explore which wavelengths would be the most advantageous for use in PDT for superficial skin diseases, and to demonstrate that the red laser exposure of 635 nm wavelength is a suitable choice for all skin types in PDT. A realistic skin model (RSM) in the Advanced Systems Analysis Program (ASAP) software has been used to create different types of skin and to simulate laser sources with wavelengths of 635, 532, 405, 365, 308 and 295 nm. The penetration depths of different kinds of laser into the skin as well as their transmission have been calculated. Comparison of the depth of penetration of different wavelengths for all types of skin has been made. A large variation is found in the penetration depth of laser lights in all skin types. The transmission of lasers on the epidermis and dermis in different skin types occur, and the transmission dose changes significantly with the skin depths. The results of the present study provide a basis for understanding the penetration depth of laser in various skin colors and the responses of the skin to laser to improve dose-drug activation in PDT. The differences in spectral transmission between the red laser and the other lasers suggest that the red laser could be a suitable laser for all skin types. © 2012 Indian Association for the Cultivation of Science.


Al-Hardan N.H.,National University of Malaysia | Abdullah M.J.,Universiti Sains Malaysia | Aziz A.A.,Universiti Sains Malaysia
Applied Surface Science | Year: 2013

Zinc oxide (ZnO) doped with chromium (Cr) was synthesized by reactive co-sputtering for gas sensing applications. The effect of varying the contents of Cr (from 1 to 4 at%) on the ZnO gas sensor response was studied. X-ray diffraction analysis reveals the high orientation of c-axis of the prepared films. The optimum operating temperature of the undoped ZnO was 400°C and shifted to 300°C for the Cr-doped ZnO under the acetone vapour. The 1% Cr doping ZnO gas sensor was most sensitive for the acetone vapour. The ability of the 1% Cr-doped ZnO to produce repeatable results under different acetone vapour concentrations was tested. The timing properties of the doped Cr ZnO gas sensor were 70 and 95 s for the rise and recovery time respectively. © 2013 Elsevier B.V.


Megat Johari M.A.,Universiti Sains Malaysia | Brooks J.J.,University of Leeds | Kabir S.,Universiti Sains Malaysia | Rivard P.,Université de Sherbrooke
Construction and Building Materials | Year: 2011

The influence of supplementary cementitious materials (SCMs), namely silica fume, metakaolin, fly ash and ground granulated blast-furnace slag, on the engineering properties of high strength concrete (HSC) has been investigated in this study. Workability, compressive strength, elastic modulus, porosity and pore size distribution were assessed in order to quantify the effects of the different materials. The results show that the inclusion of the different SCMs has considerable influence on the workability of HSC. Silica fume and metakaolin significantly enhanced the strength of HSC. Fly ash reduced the early-age strength; however, it enhanced the long-term strength of the HSC. Likewise, ground granulated blast-furnace slag impaired the early-age strength, but marginally improved the long-term strength at low replacement levels. The general effect of the different SCMs on the elastic modulus of HSC is rather small compared to their effect on strength. There are good correlations between both static and dynamic moduli and compressive strength. The EC 2 and ACI 209 provide a good estimate of static modulus of elasticity from compressive strength, while the BS8110 gives a good estimate of static modulus of elasticity from dynamic modulus of HSC containing the different SCMs. Porosity and pore size were reduced with the addition of the different SCMs. The volume of mesopores in the ranges of <15 nm and 15 - 30 nm was notably increased for HSC containing SCMs, whereas the percentage of macropores was significantly reduced. © 2010 Elsevier Ltd. All rights reserved.


Rao P.V.,University of Malaysia, Kelantan | Rao P.V.,Universiti Sains Malaysia | Gan S.H.,Universiti Sains Malaysia
Evidence-based Complementary and Alternative Medicine | Year: 2014

Cinnamon (Cinnamomum zeylanicum, and Cinnamon cassia), the eternal tree of tropical medicine, belongs to the Lauraceae family. Cinnamon is one of the most important spices used daily by people all over the world. Cinnamon primarily contains vital oils and other derivatives, such as cinnamaldehyde, cinnamic acid, and cinnamate. In addition to being an antioxidant, anti-inflammatory, antidiabetic, antimicrobial, anticancer, lipid-lowering, and cardiovascular-disease-lowering compound, cinnamon has also been reported to have activities against neurological disorders, such as Parkinson's and Alzheimer's diseases. This review illustrates the pharmacological prospective of cinnamon and its use in daily life. © 2014 Pasupuleti Visweswara Rao and Siew Hua Gan.


Lok Y.Y.,Universiti Sains Malaysia | Merkin J.H.,University of Leeds | Pop I.,Babes - Bolyai University
International Journal of Thermal Sciences | Year: 2012

The steady mixed convection flow near an axisymmetric stagnation point on a stretching or shrinking vertical cylinder is considered. The equations for the fluid flow and temperature fields reduce to similarity form that involves a Reynolds number R, a mixed convection parameter λ, a parameter γ representing the motion of the cylinder and the Prandtl number σ. Numerical solutions of the similarity equations are obtained for representative values of these parameters, which show the existence of critical values λ c = λ c (R,γ,σ) with the existence of dual solutions in the opposing (λ < 0) case. The variation of the skin friction coefficient f″(1) and heat flux θ′(1) with λ and R when σ = 1.0 are shown graphically. Also variations of λ c with R, and γ are determined again in the case when σ = 1.0. It is found that in the aiding flow (λ > 0) case solutions are possible for all λ and the asymptotic solution in the limit λ → ∞ is obtained. The nature of the solution in the asymptotic limit of large values of R is also treated in the cases when λ is of O (1) and when λ is of O (R). © 2012 Elsevier Masson SAS. All rights reserved.


Saron K.M.A.,Universiti Sains Malaysia | Hashim M.R.,Universiti Sains Malaysia | Farrukh M.A.,The University of Lahore
Applied Surface Science | Year: 2012

Stress and lattice constants are significant factors considered in evaluating the deformation mode of crystalline materials. Zinc oxide (ZnO) nanostructured thin films were prepared via the process of wet oxidation of Zn at temperatures varying from 420 to 570 °C. Structural, elemental and optical characterizations were carried out using various techniques, to investigate the properties of the samples. Scanning electron microscopy (SEM) images showed improvement in the ZnO structure and the grain size of the ZnO became larger as the oxidation temperature was increased, while maintaining a constant flow rate of wet oxygen. X-ray diffraction (XRD) patterns also showed that ZnO films suffered from compressive stress due to elongation in the lattice constant. With increase in the oxidation temperature, the compressive stress became tensile stress because of the decrease in the lattice constants. Photoluminescence (PL) spectra revealed the influence of stress on the energy band gap, with wet oxidation further giving rise to the transition of stress from compressive to tensile. © 2012 Published by Elsevier B.V.


Mujeebu M.A.,Universiti Sains Malaysia | Abdullah M.Z.,Universiti Sains Malaysia | Mohamad A.A.,Alfaisal University | Bakar M.Z.A.,Universiti Sains Malaysia
Progress in Energy and Combustion Science | Year: 2010

Porous media combustion (PMC) has interesting advantages compared with free flame combustion due to higher burning rates, increased power dynamic range, extension of the lean flammability limits, and low emissions of pollutants. Extensive experimental and numerical works were carried out and are still underway, to explore the feasibility of this interesting technology for practical applications. For this purpose, numerical modeling plays a crucial role in the design and development of promising PMC systems. This article provides an exhaustive review of the fundamental aspects and emerging trends in numerical modeling of gas combustion in porous media. The modeling works published to date are reviewed, classified according to their objectives and presented with general conclusions. Numerical modeling of liquid fuel combustion in porous media is excluded. © 2010 Elsevier Ltd. All rights reserved.


Lok Y.Y.,Universiti Sains Malaysia | Merkin J.H.,University of Leeds | Pop I.,Babes - Bolyai University
Transport in Porous Media | Year: 2013

The mixed convection boundary-layer flow on one face of a semi-infinite vertical surface embedded in a fluid-saturated porous medium is considered when the other face is taken to be in contact with a hot or cooled fluid maintaining that surface at a constant temperature Tf. The governing system of partial differential equations is transformed into a system of ordinary differential equations through an appropriate similarity transformation. These equations are solved numerically in terms of a dimensionless mixed convection parameter ε and a surface heat transfer parameter γ. The results indicate that dual solutions exist for opposing flow, ε < 0, with the dependence of the critical values εc on γ being determined, whereas for the assisting flow ε > 0, the solution is unique. Limiting asymptotic forms for both γ small and large and ε large are also discussed. © 2013 Springer Science+Business Media Dordrecht.


Dunn R.A.,Texas A&M University | Tan A.K.G.,Universiti Sains Malaysia
Breast Journal | Year: 2011

As is the case in many developing nations, previous studies of breast cancer screening behavior in Malaysia have used relatively small samples that are not nationally representative, thereby limiting the generalizability of results. Therefore, this study uses nationally representative data from the Malaysia Non-Communicable Disease Surveillance-1 to investigate the role of socio-economic status on breast cancer screening behavior in Malaysia, particularly differences in screening behaviour between ethnic groups. The decisions of 816 women above age 40 in Malaysia to screen for breast cancer using mammography, clinical breast exams (CBE), and breast self-exams (BSE) are modeled using logistic regression. Results indicate that after adjusting for differences in age, education, household income, marital status, and residential location, Malay women are less likely than Chinese and Indian women to utilize mammography, but more likely to perform BSE. Education level and urban residence are positively associated with utilization of each method, but these relationships vary across ethnicity. Higher education levels are strongly related to using each screening method among Chinese women, but have no statistically significant relationship to screening among Malays. © 2011 Wiley Periodicals, Inc.


The effect of isophorone diisocyanate-polyhydroxyl groups as a coupling agent on properties of low density polyethylene/acrylonitrile butadiene styrene/water hyacinth fibers (LDPE/A0BS/WHF) composites was studied. LDPE/ABS (50/50) blends with different unmodified and modified water hyacinth fibers (WHF) loading were prepared with Z-blade mixer at 200° C and rotor speed of 50 rpm. The results indicated that LDPE/ABS/modified WHF composites show higher values of tensile strength, Young's modulus and water absorption resistance than LDPE/ABS/unmodified WHF composites. It was also found that the modified WHF offers better thermal stability than unmodifiedWHFin the LDPE/ABS/WHF composites. © Taylor & Francis Group, LLC.


Liu W.-W.,University Malaysia Perlis | Chai S.-P.,University of Selangor | Mohamed A.R.,Universiti Sains Malaysia | Hashim U.,University Malaysia Perlis
Journal of Industrial and Engineering Chemistry | Year: 2014

Carbon nanotubes (CNTs) and graphene have built broad interest in most areas of science and engineering because of their extraordinary physical, mechanical, thermal and optical properties. Graphene is a two-dimensional one-atom-thick planar sheet of sp2-bonded carbon atoms while CNTs are a cylindrical nanostructure which composed entirely of sp2-bonded carbon atoms as well. This review presents and discusses the past and current advancement of synthesis and characterization of graphene and CNTs. The review also concludes with a brief summary and an outlook on the challenges and future prospects in the growth of graphene and CNTs. © 2013 The Korean Society of Industrial and Engineering Chemistry.


Noriman N.Z.,University Malaysia Perlis | Ismail H.,Universiti Sains Malaysia
International Journal of Polymeric Materials and Polymeric Biomaterials | Year: 2013

The utilization of nitrile glove waste will spark a great deal of interest in the rubber industry in developing cost-effective techniques to convert waste and used rubber into a processable form. Blends of styrene butadiene rubber/recycled acrylonitrile butadiene rubber (SBR/NBRr) reinforced at 85/15 blend with different ratios of a carbon black/silica (CB/Sil) hybrid filler (50/0, 40/10, 30/20, 20/30, 40/10, 0/50 phr) were tested either with or without the silane coupling agent, Si69. Results showed that the increased thermal stability of blends with Si69 is highly related to the formation of crosslinks between the filler. Thermogravimetric (TG) thermograms showed that the percentage of char residue for blends with Si69 was higher than without Si69. The differential scanning calorimetry (DSC) thermograms of both blends revealed a glass transition temperature (Tg) between 65.0°C and 66.9°C. At all blend ratios, the fatigue life of blends with Si69 was better than blends without Si69. After six months exposure to natural weather, blends with Si69 exhibited better tensile properties, retention, and morphology compared to blends without Si69. © 2013 Copyright Taylor and Francis Group, LLC.


Ahmad A.L.,Universiti Sains Malaysia | Ramli W.K.W.,Universiti Sains Malaysia | Ramli W.K.W.,University Malaysia Perlis
Separation and Purification Technology | Year: 2013

Hydrophobic PVDF membranes have been prepared through a two-stage/dual soft coagulation bath system. The prepared membranes exhibited improved hydrophobicity properties, where the contact angle values were increased, with higher efficiency of CO2 removal. Membrane prepared with two-stage coagulation bath system of 100 wt.% ethanol and 80 wt.% of NMP in water bath exhibited high water contact angle of 127°, high porosity of approximately 89% with small and narrower pore distribution. The membranes were tested in Membrane Gas Absorption (MGA) system with recorded CO2 removal efficiency of 85% for 3 h and lasted for about 10 straight hours with higher flux and 65% efficiency of CO2 removal. The modified membranes have been characterized by contact angle, microstructure, maximum pore size (P Rmax) and its distribution, surface roughness, membrane porosity and performances in MGA system. By increasing the polymer concentration, the morphology of the prepared membranes is improved due to the smaller pore characteristics and porous structure formed. The macrovoid structures severely formed in membrane with higher thickness which caused the low porosity and contact angle of the membrane. © 2012 Published by Elsevier B.V. All rights reserved.


Ali R.,University Malaysia Perlis | Daut I.,University Malaysia Perlis | Taib S.,Universiti Sains Malaysia
Renewable and Sustainable Energy Reviews | Year: 2012

As the electricity demand is affected by population growth, Malaysia towards an industrialized nation is considering the options for future energy sources for its power generation. Besides the conventional four-fuel mix, the five-fuel mix strategy under several national policies are introduced to diversify and expanding the resources to incorporate renewable energy and nuclear. In view of Malaysia will become a net energy importer by 2020, the increase in alternative energy shares at least will provide stable energy security, more economical and greener environment. In this paper, present and future energy sources are discussed to emphasis on the constraints and barriers facing Malaysia towards energy security and sustainability. Several preferences on future energy sources are under serious consideration where renewable energy (RE) is becoming one of the popular choices as Malaysia recognizes the potential of RE as sustainable and greener option. © 2012 Elsevier Ltd. All right reserved.


Romano N.,James Cook University | Romano N.,Universiti Sains Malaysia | Zeng C.,James Cook University
Aquaculture | Year: 2012

Osmoregulation is an essential physiological process for the majority of aquatic crustaceans since it enables them to cope with the changes/discrepancies between the ion concentrations within their bodies and the aquatic environments they inhabit. With the exception of strict osmoconformers, crustaceans living in all aquatic environments continually regulate their hemolymph osmolytes and ultimately, the strategy and strength of this process dictate the diversity of habitats a crustacean can successfully occupy. While the degree of the osmoregulatory response is largely salinity dependent, the actual strength is highly species-specific. This has obvious and significant implications to the crustacean aquaculture industry, a multi-billion dollar industry that is continuously growing worldwide. Unfortunately, to date, a comprehensive review discussing the implications of this crucial process in crustaceans from an aquaculture perspective is lacking. Since crustacean aquaculture is almost exclusively based on large decapods, which also forms the main body of literature, they will therefore be the main focus of review. With basic background information on the regulatory mechanisms briefly described as a foundation for necessary knowledge, the implications of increased osmoregulatory demands to crustacean aquaculture is discussed extensively based on recent literature and research conducted in our laboratory. This includes the various factors that may influence osmoregulatory abilities, the causes leading to reduced productivity at sub-optimal salinities, potential methods that may broaden tolerable salinity ranges and how osmoregulation may interact with another important physiological process, i.e. ammonia excretion, which is crucial for cultured crustaceans. At the end of the review, future research directions are suggested to advance our understanding regarding this complex process that could substantially affect crustacean aquaculture productivity. © 2011 Elsevier B.V.


Azamathulla H.M.,Universiti Sains Malaysia | Jarrett R.D.,U.S. Geological Survey
Water Resources Management | Year: 2013

Manning's roughness coefficient (n) has been widely used in the estimation of flood discharges or depths of flow in natural channels. Therefore, the selection of appropriate Manning's n values is of paramount importance for hydraulic engineers and hydrologists and requires considerable experience, although extensive guidelines are available. Generally, the largest source of error in post-flood estimates (termed indirect measurements) is due to estimates of Manning's n values, particularly when there has been minimal field verification of flow resistance. This emphasizes the need to improve methods for estimating n values. The objective of this study was to develop a soft computing model in the estimation of the Manning's n values using 75 discharge measurements on 21 high gradient streams in Colorado, USA. The data are from high gradient (S > 0.002 m/m), cobble- and boulder-bed streams for within bank flows. This study presents Gene-Expression Programming (GEP), an extension of Genetic Programming (GP), as an improved approach to estimate Manning's roughness coefficient for high gradient streams. This study uses field data and assessed the potential of gene-expression programming (GEP) to estimate Manning's n values. GEP is a search technique that automatically simplifies genetic programs during an evolutionary processes (or evolves) to obtain the most robust computer program (e. g., simplify mathematical expressions, decision trees, polynomial constructs, and logical expressions). Field measurements collected by Jarrett (J Hydraulic Eng ASCE 110: 1519-1539, 1984) were used to train the GEP network and evolve programs. The developed network and evolved programs were validated by using observations that were not involved in training. GEP and ANN-RBF (artificial neural network-radial basis function) models were found to be substantially more effective (e. g., R2 for testing/validation of GEP and RBF-ANN is 0. 745 and 0. 65, respectively) than Jarrett's (J Hydraulic Eng ASCE 110: 1519-1539, 1984) equation (R2 for testing/validation equals 0. 58) in predicting the Manning's n. © 2012 Springer Science+Business Media Dordrecht.


The effects of electron beam (EB) irradiation on the thermal properties, fatigue life and natural weathering of styrene butadiene rubber/recycled acrylonitrile-butadiene rubber (SBR/NBRr) blends were investigated. The SBR/NBRr blends were prepared at 95/5, 85/15, 75/25, 65/35, or 50/50 blend ratios with and without the presence of a 3part per hundred rubber (phr) of polyfunctional monomer, trimethylolpropane triacrylate (TMPTA). Results indicate that the crystallisation temperature (Tc) observed in polymeric blends is due to the alignment of polymer chains forming a semi-crystalline phase. Addition of TMPTA helps to align polymer chains through crosslinking. More crosslinking occurred between polymer blends with the help of TMPTA, upon irradiation. The improvement in fatigue life can also be associated with the stabilisation of SBR/NBRr blends upon irradiation and irradiation-induced crosslinking, which was accomplished with relatively low radiation-induced oxidative degradation in the presence of TMPTA. The tensile properties of both blends decreased over the periods of environmental exposure due to the effect of polymer degradation. After 6months, the irradiated SBR/NBRr blends could not retain better retention [mainly with 25, 35 or 50phr of recycled acrylonitrile-butadiene rubber (NBRr) particles] due to the samples becoming brittle over the long period of outdoor exposure. © 2011 Elsevier Ltd.


Alwash A.H.,Universiti Sains Malaysia | Alwash A.H.,Nahrain University | Abdullah A.Z.,Universiti Sains Malaysia | Ismail N.,Universiti Sains Malaysia
Journal of Hazardous Materials | Year: 2012

A new heterogeneous catalyst for sonocatalytic degradation of amaranth dye in water was synthesized by introducing titania into the pores of zeolite (NaY) through ion exchange method while Fe (III) was immobilized on the encapsulated titanium via impregnation method. XRD results could not detect any peaks for titanium oxide or Fe2O3 due to its low loading. The UV-vis analysis proved a blue shift toward shorter wavelength after the loading of Ti into NaY while a red shift was detected after the loading of Fe into the encapsulated titanium. Different reaction variables such as TiO2 content, amount of Fe, pH values, amount of hydrogen peroxide, catalyst loading and the initial dye concentration were studied to estimate their effect on the decolorization efficiency of amaranth. The maximum decolorization efficiency achieved was 97.5% at a solution pH of 2.5, catalyst dosage of 2g/L, 20mmol/100mL of H2O2 and initial dye concentration of 10mg/L. The new heterogeneous catalyst Fe/Ti-NaY was a promising catalyst for this reaction and showed minimum Fe leaching at the end of the reaction. © 2012 Elsevier B.V.


Noriman N.Z.,University Malaysia Perlis | Ismail H.,Universiti Sains Malaysia
Journal of Applied Polymer Science | Year: 2012

The recycling or reuse of waste rubber by means of blending together with polymeric materials in addition of filler such as hybrid carbon black and silica (CB/Sil) to a polymer system can provides an opportunity to explore alternative product specifications. Therefore, in this work the investigation of recycled rubber blends based on styrene butadiene rubber/recycled acrylonitrile butadiene rubber (SBR/NBRr) blends reinforced with 50/0, 40/10, 30/20, 20/30, 40/10, 0/50 phr of carbon black/silica (CB/Sil) hybrid filler treated with and without silane coupling agent (Si69) were determined. Cure characteristics, tensile properties, and morphological behavior of selected SBR/NBRr blends at a fix 85/15 blend ratio were evaluated. Results showed that, cure time t 90, minimum torque (M L), and maximum torque (M H) of CB/Sil hybrid fillers filled SBR/NBRr blends with and without Si69 increased as silica content increased. However, t 90 and M L of SBR/NBRr blends with Si69 were lower than without Si69 except for (M H). The optimum scorch time (t s2) of SBR/NBRr blends with and without Si69 was obtained at 30/20 phr of CB/Sil hybrid filler. However, t s2 of SBR/NBRr blends with Si69 were longer than SBR/NBRr blends without Si69. The incorporation of Si69 has improved the tensile properties [(tensile strength, elongation at break (E b), stress at 100% elongation (M100), and stress at 300% elongation (M300)] of CB/Sil hybrid fillers filled SBR/NBRr blends. These properties were influenced by the degree of crosslinked density as the silica content is increased. Scanning electron microscopy (SEM) of the tensile fracture surfaces indicated that, with the addition of Si69 improved the dispersion of hybrid fillers and NBRr in SBR/NBRr matrix. © 2011 Wiley Periodicals, Inc.


Romano N.,James Cook University | Romano N.,Universiti Sains Malaysia | Zeng C.,James Cook University
Reviews in Fisheries Science | Year: 2013

Nitrogenous wastes including ammonia-N, nitrite-N, and nitrate-N are increasingly becoming a global issue in aquatic ecosystems due to escalating anthropogenic activities and are a ubiquitous concern in aquaculture. These pollutants are interrelated via the nitrification cycle, with the direct metabolic product ammonia-N generally being the most toxic with high species specificity. Furthermore, while environmental factors influencing nitrogenous waste toxicity are similar, the causative underlying mechanisms are often substantially different. In this review, we focus on decapod crustaceans due to their high commercial value and likelihood of encountering these pollutants in their benthic or near-benthic habitat. While a large body of publications exists in this area, to date a comprehensive literature review on relative toxicities of all three nitrogenous wastes, physiological consequences, and adaptive mechanisms of crustaceans is lacking. Understanding these processes will likely have implications for environmental/fisheries management and the aquaculture industry. Additionally, there are strong indications that theoretical "safe" values, traditionally used for predicting toxicity thresholds, substantially underestimate the impact of nitrogenous waste on the growth and physiological condition of crustaceans. These consequences will be emphasized along with various methods of uptake, elimination, and detoxification that ultimately explain differences in nitrogenous waste toxicity to decapod crustaceans. © 2013 Copyright Taylor and Francis Group, LLC.


Sharma J.N.,Kuwait University | Kesavarao U.,Universiti Sains Malaysia
International Journal of Immunopathology and Pharmacology | Year: 2011

The present study examined the left ventricular wall thickness (LVWT), total urinary kallikrein, total plasma kininogen and mean arterial blood pressure (MABP) in diabetic and non-diabetic Wistar Kyoto (WKY) rats. The MABP was significantly raised (P<0.01) in diabetic WKY rats compared to the respective controls. The LVWT was also significantly (P<0.01) increased in diabetic WKY rats than that of control WKY rats. The mean total urinary kallikrein level and the mean total plasma kininogen level were higher (P<0.01) in diabetic WKY rats, when these rats were treated with captopril (40 mg/kg and 80 mg/kg) against the mean value obtained from control WKY rats. In conclusion, this investigation suggests that diabetes induced in these rats can cause hypertension, increased LVWT and changes in the BK-forming components. Captopril treatment caused reduction in MABP, regression of LVWT and alterations in bradykinin (BK)-forming components. The possible significance of these observations is discussed. Copyright © by BIOLIFE, s.a.s.


Othman N.,Northern University of Malaysia | Nasurdin A.M.,Universiti Sains Malaysia
Journal of Nursing Management | Year: 2013

Aim This study addressed the question of whether social support (supervisor support and co-worker support) could contribute to the variance in work engagement. Background Nurses, as customer-contact employees, play an important role in representing the organization's competence. Their attitudes and behaviour toward patients has a significant influence on patients' satisfaction and perception of quality of service. Methods The sample comprised 402 staff nurses working in three general hospitals in Peninsular Malaysia. Variables included demographic information, Utrecht Work Engagement Scale and Social Support Scale. Data analysis included descriptive statistics, correlations and regression analysis. Results Findings indicated that supervisor support was positively related to work engagement. Co-worker support was found to have no effect on work engagement. Conclusions Supervisory support is an important predictor of work engagement for nurses. Implications for nursing management Nursing management should provide more training to nurse supervisors and develop nurse mentoring programmes to encourage more support to nurses. © 2012 John Wiley & Sons Ltd.


Rohni A.M.,Northern University of Malaysia | Ahmad S.,Universiti Sains Malaysia | Pop I.,Babes - Bolyai University
International Journal of Heat and Mass Transfer | Year: 2012

The effects of suction/blowing and viscous dissipation on the steady non-linear viscous flow and heat transfer over a horizontal shrinking permeable surface of variable temperature or heat flux with a power-law velocity is numerically studied. The results complete those recently reported by Cortell [10] to the case of a shrinking surface. Particular attention is given to deriving numerical results for the critical/turning points which determine the range of existence of multiple solutions. Two cases are considered, namely prescribed surface temperature (PST) and prescribed heat flux (PHF). Dual and triple solutions are found to exist for certain parameters. © 2012 Elsevier Ltd. All rights reserved.


Khaironizam M.Z.,Universiti Sains Malaysia | Armbruster J.W.,Auburn University
Zootaxa | Year: 2015

Meristic, morphometric and distributional patterns of cyprinid fishes of the genus Neolissochilus found in Peninsular Malaysia are presented. Based on the current concept of Neolissochilus, only two species are present: N. soroides and N. hendersoni. Neolissochilus hendersoni differs from N. soroides by having lower scale and gill raker counts. Neolissochilus soroides has three mouth types (normal with a rounded snout, snout with a truncate edge, and lobe with a comparatively thick lower lip). A PCA of log-transformed measurements did not reveal significant differences between N. hendersoni and N. soroides, or between any of the morphotypes of N. soroides; however, a CVA of log-transformed measurements successfully classified 87.1% of all specimens. Removing body size by running a CVA on all of the principal components except PC1 (which was correlated with length) only slightly decreased the successful classification rate to 86.1%. Differences in morphometrics were as great between the three morphotypes of N. soroides as between any of the morphotypes and N. hendersoni suggesting that the morphotypes should be examined in greater detail with genetic tools. The PCA of morphometrics revealed separate clouds for N. hendersoni and N. soroides, but no differences between the N. soroides morphotypes. This study revealed that N. hendersoni is recorded for the first time in the mainland area of Peninsular Malaysia. Other nominal species of Neolissochilus reported to occur in the river systems of Peninsular Malaysia are discussed. Lissochilus tweediei Herre in Herre & Myers 1937 and Tor soro Bishop 1973 are synonyms of Neolissochilus soroides. Copyright © 2015 Magnolia Press.


Ong W.-J.,University of Selangor | Gui M.M.,University of Selangor | Chai S.-P.,University of Selangor | Mohamed A.R.,Universiti Sains Malaysia
RSC Advances | Year: 2013

In this communication, we demonstrate for the first time that CNT@Ni/TiO2 nanocomposites were active in the photoreduction of CO2 into methane (CH4) under visible light irradiation. The nanocomposites were synthesized via co-precipitation followed by chemical vapor deposition at 750 °C. Our results showed that the band gap of the nanocomposites was 2.22 eV, leading to high absorption of visible light. The photocatalytic results exhibited the highest CH4 yield of 0.145 μmol gcatalyst-1 h-1 using CNT@Ni/TiO 2 nanocomposites compared with Ni/TiO2 and pure anatase TiO2 owing to the synergistic combination of the CNTs and TiO 2. © 2012 The Royal Society of Chemistry.


Tan L.-L.,University of Selangor | Ong W.-J.,University of Selangor | Chai S.-P.,University of Selangor | Mohamed A.R.,Universiti Sains Malaysia
Chemical Communications | Year: 2014

A facile and dopant-free strategy was employed to fabricate oxygen-rich TiO2 (O2-TiO2) with enhanced visible light photoactivity. Such properties were achieved by the in situ generation of oxygen through the thermal decomposition of the peroxo-titania complex. The O 2-TiO2 photocatalyst exhibited high photoactivity towards CO2 reduction under visible light. © the Partner Organisations 2014.


Ong W.-J.,University of Selangor | Tan L.-L.,University of Selangor | Chai S.-P.,University of Selangor | Yong S.-T.,University of Selangor | Mohamed A.R.,Universiti Sains Malaysia
ChemSusChem | Year: 2014

Titanium dioxide (TiO2) is one of the most widely investigated metal oxides because of its extraordinary surface, electronic, and photocatalytic properties. However, the large band gap of TiO2 and the considerable recombination of photogenerated electron-hole pairs limit its photocatalytic efficiency. Therefore, research attention is being increasingly directed towards engineering the surface structure of TiO2 on the atomic level (namely morphological control of {001} facets on the micro-and nanoscale) to fine-tune its physicochemical properties; this could ultimately lead to the optimization of selectivity and reactivity. This Review encompasses the fundamental principles to enhance the photocatalytic activity by using highly reactive {001}-faceted TiO2-based composites. The current progress of such composites, with particular emphasis on the photodegradation of pollutants and photocatalytic water splitting for hydrogen generation, is also discussed. The progresses made are thoroughly examined for achieving remarkable photocatalytic performances, with additional insights with regard to charge transfer. Finally, a summary and some perspectives on the challenges and new research directions for future exploitation in this emerging frontier are provided, which hopefully would allow for harnessing the outstanding structural and electronic properties of {001} facets for various energy-and environmental-related applications. Face the life of TiO2: Research attention has been recently directed increasingly towards the engineering of the surface structure of TiO2-based photocatalysts based on the most fundamental and atomic level, namely morphological control of {001} facets. Using this fine-tuning of the physicochemical properties, their outstanding structural and electronic properties can be harnessed for various energy-and environmental-related applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Ong W.-J.,University of Selangor | Tan L.-L.,University of Selangor | Chai S.-P.,University of Selangor | Yong S.-T.,University of Selangor | Mohamed A.R.,Universiti Sains Malaysia
Nanoscale | Year: 2014

Titanium dioxide (TiO2) is one of the most widely investigated metal oxides due to its extraordinary surface, electronic and catalytic properties. However, the large band gap of TiO2 and massive recombination of photogenerated electron-hole pairs limit its photocatalytic and photovoltaic efficiency. Therefore, increasing research attention is now being directed towards engineering the surface structure of TiO2 at the most fundamental and atomic level namely morphological control of {001} facets in the range of microscale and nanoscale to fine-tune its physicochemical properties, which could ultimately lead to the optimization of its selectivity and reactivity. The synthesis of {001}-faceted TiO2 is currently one of the most active interdisciplinary research areas and demonstrations of catalytic enhancement are abundant. Modifications such as metal and non-metal doping have also been extensively studied to extend its band gap to the visible light region. This steady progress has demonstrated that TiO2-based composites with {001} facets are playing and will continue to play an indispensable role in the environmental remediation and in the search for clean and renewable energy technologies. This review encompasses the state-of-the-art research activities and latest advancements in the design of highly reactive {001} facet-dominated TiO2via various strategies, including hydrothermal/solvothermal, high temperature gas phase reactions and non-hydrolytic alcoholysis methods. The stabilization of {001} facets using fluorine-containing species and fluorine-free capping agents is also critically discussed in this review. To overcome the large band gap of TiO2 and rapid recombination of photogenerated charge carriers, modifications are carried out to manipulate its electronic band structure, including transition metal doping, noble metal doping, non-metal doping and incorporating graphene as a two-dimensional (2D) catalyst support. The advancements made in these aspects are thoroughly examined, with additional insights related to the charge transfer events for each strategy of the modified-TiO2 composites. Finally, we offer a summary and some invigorating perspectives on the major challenges and new research directions for future exploitation in this emerging frontier, which we hope will advance us to rationally harness the outstanding structural and electronic properties of {001} facets for various environmental and energy-related applications. © 2014 The Royal Society of Chemistry.


Seah C.-M.,Universiti Sains Malaysia | Chai S.-P.,University of Selangor | Mohamed A.R.,Universiti Sains Malaysia
Carbon | Year: 2014

Graphene has become the focus of research recently due to its properties. Various methods have been proposed for the synthesis of graphene, and chemical vapour deposition (CVD) appears to be the most promising route for synthesising large-area graphene. Use of Ru, Ir, Ni, or Co lead to a segregation growth procedure, in which carbon dissolves into the bulk metals at a high temperature and segregates to form graphene after reaching the carbon saturation, and the graphene expand with carpet growth mode. For Cu catalyst, the formation of graphene can be explained by the surface growth model, in which carbon aggregates at the surface of Cu to form graphene. Graphene are formed at different mechanism on different crystalline facets for Pt, Ni and Cu. Meanwhile Ru(0 0 0 1) and Ir(1 1 1) only suitable for graphene formation for respective metals. This review discusses the fundamental mechanisms of the synthesis of graphene from various transition metals under various circumstances through a CVD process and concludes by addressing the challenges involved in large-scale graphene synthesis and the reuse of the catalysts. © 2013 Elsevier Ltd. All rights reserved.


Tan L.-L.,University of Selangor | Chai S.-P.,University of Selangor | Mohamed A.R.,Universiti Sains Malaysia
ChemSusChem | Year: 2012

Graphene is one of the most promising materials in the field of nanotechnology and has attracted a tremendous amount of research interest in recent years. Due to its large specific surface area, high thermal conductivity, and superior electron mobility, graphene is regarded as an extremely attractive component for the preparation of composite materials. At the same time, the use of photocatalysts, particularly TiO 2, has also been widely studied for their potential in addressing various energy and environmental-related issues. However, bare TiO 2 suffers from low efficiency and a narrow light-response range. Therefore, the combination of graphene and TiO 2 is currently one of the most active interdisciplinary research areas and demonstrations of photocatalytic enhancement are abundant. This Review presents and discusses the current development of graphene-based TiO 2 photocatalysts. The theoretical framework of the composite, the synthetic strategies for the preparation and modification of graphene-based TiO 2 photocatalysts, and applications of the composite are reviewed, with particular attention on the photodegradation of pollutants and photocatalytic water splitting for hydrogen generation. Power in the mix: The incorporation of TiO 2 onto graphene is gaining tremendous research interest as it presents the opportunity to simultaneously cover all mechanisms of photocatalytic enhancement. Herein, the theoretical framework, synthetic strategies for the preparation and modification, and applications of these photocatalysts are reviewed, with particular attention on the photodegradation of pollutants and photocatalytic water splitting for hydrogen generation. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Zerafat Angiz L M.,Northern University of Malaysia | Mustafa A.,Universiti Sains Malaysia
Knowledge-Based Systems | Year: 2013

Data envelopment analysis (DEA) is a nonparametric model which evaluates the relative efficiencies of decision-making units (DMUs). These DMUs produce multiple outputs by using multiple inputs and the relative efficiency is evaluated using a ratio of total weighted output to total weighted input. In this paper an alternative interpretation of efficiency is first given. The interpretation is based on the fuzzy concept even though the inputs and outputs data are crisp numbers. With the interpretation, a new model for ranking DMUs in DEA is proposed and a new perspective of viewing other DEA models is now made possible. The model is then extended to incorporate situations whereby some inputs or outputs, in a fuzzy sense, are almost discretionary variables. © 2013 Elsevier B.V. All rights reserved.


Shahbaz M.,COMSATS Institute of Information Technology | Lean H.H.,Universiti Sains Malaysia | Farooq A.,COMSATS Institute of Information Technology
Renewable and Sustainable Energy Reviews | Year: 2013

Natural gas is a dominant fuel in Pakistan. It offers the cheapest and a cleaner alternative source of energy. This paper examines the relationship of natural gas consumption and economic growth in Pakistan. We include capital, labor and exports in the model with multivariate framework. The ARDL bounds testing approach to cointegration and innovative accounting approach are employed to investigate the dynamic causality relationships among the variables. We find the existence of long-run relationship among the variables. Natural gas consumption, capital, labor and exports are positively affecting economic growth in Pakistan. Furthermore, we support the natural gas consumption-led- growth hypothesis and suggest that natural gas conservation policies may retard economic growth. © 2012 Elsevier Ltd. All rights reserved.


Seah C.-M.,Universiti Sains Malaysia | Chai S.-P.,University of Selangor | Mohamed A.R.,Universiti Sains Malaysia
Carbon | Year: 2011

Vertically aligned carbon nanotubes (ACNTs) are bundles of carbon nanotubes oriented perpendicular to a substrate, and horizontally aligned CNTs are parallel to the substrate. Their dense and orderly arrangement, along with outstanding physical and chemical properties, enables ACNTs to be used in various fields. The methods of synthesising ACNTs can be classified into single-step and double-step techniques. Thermal pyrolysis and flame synthesis are the common single-step methods, and both are relatively simple. The double-step methods, including catalyst coating and chemical vapour deposition, provide more control over the catalyst morphology. This review explores different methods used for ACNT growth, the process parameters that determine the morphology of ACNTs and the applications of structured ACNTs. © 2011 Elsevier Ltd. All rights reserved.


Rohni A.M.,Northern University of Malaysia | Ahmad S.,Universiti Sains Malaysia | Ismail A.I.M.,Universiti Sains Malaysia | Pop I.,Babes - Bolyai University
International Journal of Thermal Sciences | Year: 2013

In this paper, we investigate theoretically the problem of steady laminar two-dimensional boundary layer flow and heat transfer of an incompressible viscous fluid in the presence of buoyancy force over an exponentially shrinking vertical sheet with suction. The shrinking velocity and wall temperature are assumed to have specific exponential function forms. The governing equations are first transformed to similarity equations using an appropriate similarity transformation. The resulting equations were then solved numerically using shooting technique involving fourth-order Runge-Kutta method and Newton-Raphson method. The influence of mixed convection/buoyancy parameter λ, suction parameter s and Prandtl number Pr on the flow and heat transfer characteristics is examined and discussed. Numerical results indicate that the presence of buoyancy force would contribute to the existence of triple solutions to the flow and heat transfer for particular value of pertinent parameters. It is different for the non-buoyant flow case i.e. when the buoyancy force is absent, the problem admits only dual solutions. Further, this study also reveals that the features of flow and heat transfer characteristics are significantly affected by buoyancy parameter λ, suction parameter s and Prandtl number Pr. © 2012 Elsevier Masson SAS. All rights reserved.


Tan L.-L.,University of Selangor | Ong W.-J.,University of Selangor | Chai S.-P.,University of Selangor | Mohamed A.R.,Universiti Sains Malaysia
Applied Catalysis B: Environmental | Year: 2015

The design and architecture of visible-light-active photocatalysts is a key aim among material scientists for the efficient utilization of renewable solar energy. In this paper, a series of noble metal (Pt, Pd, Ag and Au) nanoparticles supported on reduced graphene oxide/TiO2 (GT) were successfully synthesized through a dual step process. In the first step, GT nanocomposites were prepared using a solvothermal method. The as-prepared hybrid nanostructures were subsequently employed as supporting materials for the dispersion of metal nanoparticles. A simple polyol process was used to respectively reduce metal ions (PtCl62-, Pd2+, Ag+, and AuCl4-) into metal (Pt, Pd, Ag and Au) nanoparticles on GT. The three-component nanocomposites exhibited enhanced photocatalytic activities toward the photoreduction of CO2 into CH4 gas under the irradiation of typical daylight bulbs. This was attributed to the multiplex phenomena such as an enhanced utilization of visible light, efficient electron transfer in the noble metal-doped GT nanojunctions and interfacial electron transfer in the reduced graphene oxide (rGO) sheets, as evidenced by UV-vis and PL characterizations. Among the noble metals studied, the Pt-doped GT nanocomposites showed the highest efficiency in reducing CO2. A total CH4 yield of 1.70μmol/gcat was achieved after 6h of light irradiation, which was 2.6 and 13.2 folds higher in comparison to GT and commercial P25, respectively. Based on the experimental results obtained, a plausible mechanism for the photocatalytic process associated with Pt-GT was proposed. © 2014 Elsevier B.V.


Shahbaz M.,COMSATS Institute of Information Technology | Lean H.H.,Universiti Sains Malaysia | Shabbir M.S.,COMSATS Institute of Information Technology
Renewable and Sustainable Energy Reviews | Year: 2012

The paper is an effort to fill the gap in the energy literature with a comprehensive country study of Pakistan. We investigate the relationship between CO 2 emissions, energy consumption, economic growth and trade openness in Pakistan over the period of 1971-2009. Bounds test for cointegration and Granger causality approach are employed for the empirical analysis. The result suggests that there exists a long-run relationship among the variables and the Environmental Kuznets Curve (EKC) hypothesis is supported. The significant existence of EKC shows the country's effort to condense CO 2 emissions and indicates certain achievement of controlling environmental degradation in Pakistan. Furthermore, we find a one-way causal relationship running from economic growth to CO 2 emissions. Energy consumption increases CO 2 emissions both in the short and long runs. Trade openness reduces CO 2 emissions in the long run but it is insignificant in the short run. In addition, the change of CO 2 emissions from short run to the long span of time is corrected by about 10% yearly. © 2012 Elsevier Ltd. All rights reserved.


Gui M.M.,University of Selangor | Yap Y.X.,University of Selangor | Chai S.-P.,University of Selangor | Mohamed A.R.,Universiti Sains Malaysia
International Journal of Greenhouse Gas Control | Year: 2013

Multi-walled carbon nanotubes (MWCNTs) were modified with (3-aminopropyl)triethoxysilane (APTES) solution in a two-step process. In the first step, the MWCNTs were pre-treated with sulfuric acid and nitric acid (5 molar each mixed at ratio of 3:1, v/v) with the aims to remove metal catalysts impurities and to introduce carboxyl groups on the MWCNT surface. In the second step, the acid pre-treated MWCNTs were functionalized with APTES at 105°C under various reflux durations. The characteristics of the functionalized MWCNTs were studied by Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and Raman spectroscopy. TG analysis shows an increase in APTES loading with increasing reflux duration, giving the maximum loading of 13.75wt%. This result suggests that as reflux duration increased, more amine groups were attached covalently on the MWCNT surface, forming effective mechanism sites for CO2 adsorption. The highest CO2 uptake of 75.4mg CO2 adsorbed/g adsorbent was achieved by the amine-functionalized MWCNTs, indicating its superior performance than some other commonly used adsorbents such as SBA-15. © 2013 Elsevier Ltd.


Razak N.A.,Universiti Sains Malaysia | Dimitriadis G.,University of Liège
Journal of Fluids and Structures | Year: 2014

This paper presents the results of experiments carried out on mechanical wings undergoing active root flapping and pitching in the wind tunnel. The objective of the work is to investigate the effect of the pitch angle oscillations and wing profile on the aerodynamic forces generated by the wings. The experiments were repeated for a different reduced frequency, airspeed, flapping and pitching kinematics, geometric angle of attack and wing sections (one symmetric and two cambered airfoils). A specially designed mechanical flapper was used, modelled on large migrating birds. It is shown that, under pitch leading conditions, good thrust generation can be obtained at a wide range of Strouhal numbers if the pitch angle oscillation is adjusted accordingly. Consequently, high thrust was measured at both the lowest and highest tested Strouhal numbers. Furthermore, the work demonstrates that the aerodynamic forces can be sensitive to the Reynolds number, depending on the camber of the wings. Under pitch lagging conditions, where the effective angle of attack amplitude is highest, the symmetric wing was affected by the Reynolds number, generating less thrust at the lowest tested Reynolds value. In contrast, under pure flapping conditions, where the effective angle of attack amplitude was lower but still significant, it was the cambered wings that demonstrated Reynolds sensitivity. © 2014 Elsevier Ltd.


Shahbaz M.,COMSATS Institute of Information Technology | Lean H.H.,Universiti Sains Malaysia
Energy | Year: 2012

This study revisits the relationship between electricity consumption and economic growth in Pakistan by controlling and investigating the effects of two major production factors - capital and labor. The empirical evidence confirms the cointegration among the variables and indicates that electricity consumption has a positive effect on economic growth. Moreover, bi-directional Granger causality between electricity consumption and economic growth has been found. The finding suggests that adoption of electricity conservation policies to conserve energy resources may unwittingly decline economic growth and the lower growth rate will in turn further decrease the demand for electricity. Therefore, government contemplating such conservationist policies should instead explore and develop alternate sources of energy as a strategy rather than just increasing electricity production per se in order to meet the rising demand for electricity in their quest towards sustaining development in the country. © 2012 Elsevier Ltd.


Shahbaz M.,COMSATS Institute of Information Technology | Lean H.H.,Universiti Sains Malaysia
Energy Policy | Year: 2012

This paper assesses the relationship among energy consumption, financial development, economic growth, industrialization and urbanization in Tunisia from 1971 to 2008. The autoregressive distributed lag bounds testing approach to cointegration and Granger causality tests is employed for the analysis. The result confirms the existence of long-run relationship among energy consumption, economic growth, financial development, industrialization and urbanization in Tunisia. Long-run bidirectional causalities are found between financial development and energy consumption, financial development and industrialization, and industrialization and energy consumption. Hence, sound and developed financial system that can attract investors, boost the stock market and improve the efficiency of economic activities should be encouraged in the country. Nevertheless, promoting industrialization and urbanization can never be left out from the process of development. We add light to policy makers with the role of financial development, industrialization and urbanization in the process of economic development. © 2011 Elsevier Ltd.


Ong W.-J.,University of Selangor | Tan L.-L.,University of Selangor | Chai S.-P.,University of Selangor | Yong S.-T.,University of Selangor | Mohamed A.R.,Universiti Sains Malaysia
Nano Energy | Year: 2015

In this work, we reported a 2D/2D hybrid heterojunction photocatalyst with effective interfacial contact by incorporating reduced graphene oxide (rGO) and protonated g-C3N4 (pCN) synthesized by a novel combined ultrasonic dispersion and electrostatic self-assembly strategy followed by a NaBH4-reduction process. The resulting 2D rGO-hybridized pCN (rGO/pCN) nanostructures formed an intimate contact across the heterojunction interface as supported by the electron microscopy analysis. The rGO/pure g-C3N4 (rGO/CN) developed without the modification of surface charge on g-C3N4 has also been prepared for comparison. Compared with pure g-C3N4 and rGO/CN, the rGO/pCN photocatalysts demonstrated a remarkable enhancement on the CO2 reduction in the presence of H2O vapor to CH4 under a low-power energy-saving daylight bulb at ambient temperature and atmospheric pressure. The optimized 15wt% rGO/pCN (15rGO/pCN) exhibited the highest CH4 evolution of 13.93μmol gcatalyst-1 with a photochemical quantum yield of 0.560%, which was 5.4- and 1.7-folds enhancement over pCN and 15rGO/CN samples, respectively. This was ascribed to the addition of rGO with pCN in a controlled ratio as well as sufficient interfacial contact between rGO and pCN across the rGO/pCN heterojunction for efficient charge transfer to suppress the recombination of electron-hole pairs as evidenced by the electron microscopy, zeta potential and photoluminescence studies. In addition, the 15rGO/pCN possessed a moderately high stability after three successive cycles with no obvious change in the production of CH4 from CO2 reduction. Lastly, a visible-light photocatalytic mechanism associated with rGO/pCN hybrid nanoarchitectures was presented. © 2015 Elsevier Ltd.


Seah C.-M.,Universiti Sains Malaysia | Chai S.-P.,University of Selangor | Ichikawa S.,Osaka University | Mohamed A.R.,Universiti Sains Malaysia
Carbon | Year: 2012

Single-walled carbon nanotubes (SWCNTs) have been grown on flat silicon oxide substrates by the decomposition of methane. The spin-coated iron(III) nitrate with a concentration of 40 mmol/L diluted in a colloidal solution with ratio 1:1 (v/v) of absolute ethanol to PEG-400 was found to form iron nanoparticles that are small enough to grow SWCNTs. The role of PEG was to interact with iron ions and encapsulate the iron, thus preventing agglomeration, while the absolute ethanol isolated the PEG-iron micelles. The ratio of absolute ethanol to PEG controlled the viscosity and the distance between PEG-encapsulated iron micelles, and subsequently governed the size and density of the iron nanoparticles formed. To reduce the effect of surface tension that will disturb the uniformity of a thin colloid film, -OH groups were introduced on the silicon wafer by a piranha solution and the hydrogen bonds formed with PEG preserved the uniformity of the iron nanoparticle distribution during the synthesis of SWCNTs. © 2011 Elsevier Ltd. All rights reserved.


Daud W.R.W.,Universiti Sains Malaysia | Law K.-N.,University of Quebec at Trois - Rivieres
BioResources | Year: 2011

This paper reviews the physical and chemical characteristics of fibers from the stem, fronds, and empty fruit bunches of oil palm tree in relation to their papermaking properties. Challenges regarding the use of this nonwood material for papermaking are raised, and possible solutions to them are given. A vision for the complete utilization of oil palm biomass is also outlined.


Soid S.N.,Universiti Sains Malaysia | Soid S.N.,University of Kuala Lumpur | Zainal Z.A.,Universiti Sains Malaysia
Energy | Year: 2011

The number of studies on spray and combustion characteristics in IC (internal combustion) engines using optical techniques has rapidly increased in the past few years due to an increase in the number of alternative fuels and stricter emission standard regulations. This study investigates better ways of controlling the combustion process, thus ensuring optimum performance and minimum emission levels produced during the combustion process. Alternative fuels such as CNG (compressed natural gas), biodiesel and hydrogen have been studied by many researchers due to their relative low environmental impact. Meanwhile, for conventional fuels such as gasoline and diesel, studies have focused on spray characteristics to provide better air/fuel mixtures in order to produce a cleaner combustion process. Few experimental works have investigated the effects of modifications to the injector itself, for example, varying the injection rate, injection pressure, etc. In order to provide a better understanding of spray and combustion characteristics, researchers have studied macroscopic and microscopic parameters using optical techniques. This paper presents the significance of spray and combustion study with optical techniques that have been reported by previous researchers in order to provide in depth knowledge as assistance to readers interested in this research area. © 2010 Elsevier Ltd.


Teh S.Y.,Universiti Sains Malaysia | Khoo M.B.C.,Universiti Sains Malaysia | Wu Z.,Nanyang Technological University
Computers and Industrial Engineering | Year: 2011

The sum of squares double exponentially weighted moving average (SS-DEWMA) chart is proposed to improve the performance of the single SS-EWMA chart, in the detection of initial out-of-control signals. The SS-DEWMA chart uses the sum of squares statistic and it simultaneously monitors the process mean and variance in a single chart. A simulation study is conducted to show that the optimal SS-DEWMA chart provides better zero state average run length (ARL) and standard deviation of the run length (SDRL) performances than the optimal SS-EWMA chart. In addition, as suggested by one of the reviewers, the cyclical steady state ARLs and SDRLs of the SS-DEWMA and SS-EWMA charts are compared, where it is found that the former did not perform as well as the latter. Note that to the best of the authors' knowledge, a study on DEWMA type charts' steady state ARL and SDRL performances has yet to be made in the literature. A situation in which the SS-DEWMA chart could be more useful than the SS-EWMA chart is explained in Sections 4 and 6. © 2011 Elsevier Ltd. All rights reserved.


Karim Z.,Universiti Sains Malaysia | Adnan R.,Universiti Sains Malaysia | Ansari M.S.,University of Delhi
PLoS ONE | Year: 2012

Chemical synthesis of Ag-NPs was carried out using reduction method. The reduction mechanistic approach of silver ions was found to be a basic clue for the formation of the Ag-NPs. The nanoparticles were characterized by UV-vis, FT-IR and TEM analysis. We had designed some experiments in support of our hypothesis, "low concentrations of novel nanoparticles (silver and gold) increases the activity of plant peroxidases and alter their structure also", we had used Ag-NPs and HRP as models. The immobilization/interaction experiment had demonstrated the specific concentration range of the Ag-NPs and within this range, an increase in HRP activity was reported. At 0.08 mM concentration of Ag-NPs, 50% increase in the activity yield was found. The U.V-vis spectra had demonstrated the increase in the absorbance of HRP within the reported concentration range (0.06-0.12 mM). Above and below this concentration range there was a decrease in the activity of HRP. The results that we had found from the fluorescence spectra were also in favor of our hypothesis. There was a maximum increase in ellipticity and α-helix contents in the presence of 0.08 mM concentration of Ag-NPs, demonstrated by circular dichroism (CD) spectra. Finally, incubation of a plant peroxidase, HRP with Ag-NPs, within the reported concentration range not only enhances the activity but also alter the structure. © 2012 Karim et al.


Lee C.-C.,Universiti Sains Malaysia | Neoh K.-B.,Kyoto University
Journal of Economic Entomology | Year: 2014

The efficacy of chitin synthesis inhibitors (CSIs) against fungus-growing termites is known to vary. In this study, 0.1% chlorfluazuron (CFZ) cellulose bait was tested against medium and large field colonies of Macrotermes gilvus (Hagen). The termite mounds were dissected to determine the health of the colony. Individual termites (i.e., workers and larvae) and fungus combs were subjected to gas chromatography-mass spectrometry (GC-MS) analysis to detect the presence of CFZ. In this study, 540.0 ± 25.8 g (or equivalent to 540.0 ± 25.8 mg active ingredient) and 680.0 ± 49.0 g (680.0 ± 49.0 mg active ingredient) of bait matrix were removed by the medium- and large-sized colonies, respectively, after baiting. All treated medium-sized colonies were moribund. The dead termites were scattered in the mound, larvae were absent, population size had decreased by 90%, and the queens appeared unhealthy. In contrast, no or limited effects were found in large-sized colonies. Only trace amounts of CFZ were detected in workers, larvae, and fungus combs, and the population of large-sized colonies had declined by only up to 40%. This might be owing to the presence of large amount of basidiomycete fungus and a drastic decrease of CFZ content per unit fungus comb (a main food source of larvae) in the large-sized colonies, and hence reduced the toxic effect and longer time is required to accumulate the lethal dose in larvae. Nevertheless, we do not deny the possibility of CSI bait eliminating or suppressing the higher termite if the test colonies could pick up adequate lethal dose by installing more bait stations and prolonging the baiting period. © 2014 Entomological Society of America.


Zakaria S.M.,Universiti Sains Malaysia | Sharif Zein S.H.,Universiti Sains Malaysia | Othman M.R.,Universiti Sains Malaysia | Yang F.,Radboud University Nijmegen | Jansen J.A.,Radboud University Nijmegen
Tissue Engineering - Part B: Reviews | Year: 2013

Hydroxyapatite is a biocompatible material that is extensively used in the replacement and regeneration of bone material. In nature, nanostructured hydroxyapatite is the main component present in hard body tissues. Hence, the state of the art in nanotechnology can be exploited to synthesize nanophase hydroxyapatite that has similar properties with natural hydroxyapatite. Sustainable methods to mass-produce synthetic hydroxyapatite nanoparticles are being developed to meet the increasing demand for these materials and to further develop the progress made in hard tissue regeneration, especially for orthopedic and dental applications. This article reviews the current developments in nanophase hydroxyapatite through various manufacturing techniques and modifications. © Copyright 2013, Mary Ann Liebert, Inc. 2013.


Khan F.N.,Hong Kong Polytechnic University | Khan F.N.,Universiti Sains Malaysia | Zhou Y.,Hong Kong Polytechnic University | Lau A.P.T.,Hong Kong Polytechnic University | Lu C.,Hong Kong Polytechnic University
Optics Express | Year: 2012

We propose a simple and cost-effective technique for modulation format identification (MFI) in next-generation heterogeneous fiber-optic networks using an artificial neural network (ANN) trained with the features extracted from the asynchronous amplitude histograms (AAHs). Results of numerical simulations conducted for six different widely-used modulation formats at various data rates demonstrate that the proposed technique can effectively classify all these modulation formats with an overall estimation accuracy of 99.6% and also in the presence of various link impairments. The proposed technique employs extremely simple hardware and digital signal processing (DSP) to enable MFI and can also be applied for the identification of other modulation formats at different data rates without necessitating hardware changes. © 2012 Optical Society of America.


Ayodele O.B.,Universiti Sains Malaysia | Ayodele O.B.,National Institute of Design | Lim J.K.,Universiti Sains Malaysia | Hameed B.H.,Universiti Sains Malaysia
Applied Catalysis A: General | Year: 2012

Degradation of amoxicillin (AMX) was achieved using pillared montmorillonite ferric oxalate (PMFeOx) catalyst in photo-Fenton process. The catalyst was prepared by aluminum pillaring of mild acid treated montmorillonite (MATM) clay followed by incorporation of ferric oxalate. The PMFeOx catalyst produced was characterized. XRD results revealed the intercalation of aluminum with an increase in basal spacing from 1.24 to ∼1.69 nm, the specific surface area also increased from 164.94 to 211.61 m 2 g -1. SEM images of PMFeOx showed the formation of irregular flaky morphology with random orientation. The FTIR profile at relevant wavenumbers detected intercalation of aluminum and incorporation of iron. The optimum condition that achieved 99.65% and 84.26% initial concentration reduction and COD removal respectively, for 40 ppm AMX solution was 15% excess H 2O 2 and 2.0 g PMFeOx catalyst loading at 40 °C in 10 min. The catalyst displayed good efficiency in degrading amoxicillin. © 2011 Elsevier B.V.


Abdul Khalil H.P.S.,Universiti Sains Malaysia | Bhat I.U.H.,Universiti Sains Malaysia | Jawaid M.,University of Technology Malaysia | Zaidon A.,University Putra Malaysia | And 2 more authors.
Materials and Design | Year: 2012

The reduction in harmful destruction of ecosystem and to produce low cost polymeric reinforced composites, the researchers are emerging with policies of manufacturing the composites using natural fibres which are entirely biodegradable. These policies had generated safe strategies to protect our environment. The utilization of bamboo fibres as reinforcement in composite materials has increased tremendously and has undergone high-tech revolution in recent years as a response to the increasing demand for developing biodegradable, sustainable, and recyclable materials. The amalgamation of matrix and natural fibres yield composite possessing best properties of each component. Various matrices used currently are soft and flexible in comparison to natural fibres their combination leads to composite formation with high strength-to-weight ratios. The rapid advancement of the technology for making industry products contributes consumer the ease of making a suitable choice and own desirable tastes. Researchers have expanded their expertise in the product design by applying the usage of raw materials like bamboo fibre which is stronger as well as can be utilized in generating high end quality sustainable industrial products. Thereby, this article gives critical review of the most recent developments of bamboo fibre based reinforced composites and the summary of main results presented in literature, focusing on the processing methodology and ultimate properties of bamboo fibres with polymeric matrices and applications in well designed economical products. © 2012 Elsevier Ltd.


Faisal A.,Muhammadiyah University of Sumatera Utara | Majid T.A.,Universiti Sains Malaysia | Hatzigeorgiou G.D.,Democritus University of Thrace
Soil Dynamics and Earthquake Engineering | Year: 2013

The present study focuses on the influence of repeated earthquakes on the maximum story ductility demands of three-dimensional inelastic concrete frames. A comprehensive assessment is conducted using generic frames with 3-, 6-, 12-, and 18-story structures. Each is assumed to have behaviour factors of 1.5, 2, 4, and 6 referring to Eurocode 8. Stiffness and strength degrading hysteresis rule to represent reinforced concrete structure is considered in the plastic hinge of members. Twenty ground motions are selected, and single, double, and triple events of synthetic repeated earthquakes are considered. Some interesting findings are provided showing that repeated earthquakes significantly increase the story ductility demand of inelastic concrete frames. On average, relative increment of maximum story ductility demand is experienced 1.4 and 1.3 times when double and triple events of repeated earthquakes are induced, respectively. Empirical relationships are also provided to predict these increments where their efficiency is presented examining characteristic 3- and 8-story reinforced concrete buildings. © 2012 Elsevier Ltd.


Naher H.,Universiti Sains Malaysia | Naher H.,Brac University | Abdullah F.A.,Universiti Sains Malaysia | Akbar M.A.,University of Rajshahi
PLoS ONE | Year: 2013

The generalized and improved G′/G-expansion method is a powerful and advantageous mathematical tool for establishing abundant new traveling wave solutions of nonlinear partial differential equations. In this article, we investigate the higher dimensional nonlinear evolution equation, namely, the (3+1)-dimensional modified KdV-Zakharov-Kuznetsev equation via this powerful method. The solutions are found in hyperbolic, trigonometric and rational function form involving more parameters and some of our constructed solutions are identical with results obtained by other authors if certain parameters take special values and some are new. The numerical results described in the figures were obtained with the aid of commercial software Maple. © 2013 Naher et al.


Koriem K.M.M.,National Research Center of Egypt | Koriem K.M.M.,Universiti Sains Malaysia | Soliman R.E.,Cairo University
Journal of Toxicology | Year: 2014

Methamphetamine intoxication can cause acute hepatic failure. Chlorogenic and caftaric acids are the major dietary polyphenols present in various foods. The aim of this study was to evaluate the protective role of chlorogenic and caftaric acids in liver toxicity and oxidative stress induced by methamphetamine in rats. Thirty-two male albino rats were divided into 4 equal groups. Group 1, which was control group, was injected (i.p) with saline (1 mL/kg) twice a day over seven-day period. Groups 2, 3, and 4 were injected (i.p) with methamphetamine (10 mg/kg) twice a day over seven-day period, where groups 3 and 4 were injected (i.p) with 60 mg/kg chlorogenic acid and 40mg/kg caftaric acid, respectively, one day before methamphetamine injections. Methamphetamine increased serum aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, bilirubin, cholesterol, low-density lipoprotein, and triglycerides. Also, malondialdehyde in serum, liver, and brain and plasma and liver nitric oxide levels were increased while methamphetamine induced a significant decrease in serum total protein, albumin, globulin, albumin/globulin ratio, brain serotonin, norepinephrine and dopamine, blood and liver superoxide dismutase, and glutathione peroxidase levels. Chlorogenic and caftaric acids prior to methamphetamine injections restored all the above parameters to normal values. In conclusion, chlorogenic and caftaric acids before methamphetamine injections prevented liver toxicity and oxidative stress where chlorogenic acid was more effective. Copyright © 2014 K. M. M. Koriem and R. E. Soliman.


Umar M.,RMIT University | Roddick F.,RMIT University | Fan L.,RMIT University | Aziz H.A.,Universiti Sains Malaysia
Chemosphere | Year: 2013

The extensive use of Bisphenol A (BPA) in the plastics industry has led to increasing reports of its presence in the aquatic environment, with concentrations of ngL-1 to μgL-1. Various advanced oxidation processes, including ozonation, have been shown to effectively degrade BPA. This paper reviews the current advancements in using ozone to remove BPA from water and wastewater. Most of the published work on the oxidation of BPA by ozone has focused on the efficiency of BPA removal in terms of the disappearance of BPA, and the effect of various operational parameters such as ozone feed rate, contact time and pH; some information is available on the estrogenic activity of the treated water. Due to increasing operational reliability and cost effectiveness, there is great potential for industrial scale application of ozone for the treatment of BPA. However, there is a significant lack of information on the formation of oxidation by-products and their toxicities, particularly in more complex matrices such as wastewater, and further investigation is needed for a better understanding of the environmental fate of BPA. © 2012 Elsevier Ltd.


Eltayeb T.K.,Dhofar University | Zailani S.,Universiti Sains Malaysia | Ramayah T.,Universiti Sains Malaysia
Resources, Conservation and Recycling | Year: 2011

The relationship between green supply chain initiatives and performance outcomes has been subject to numerous studies but the results are not conclusive. This study tries to assess the actual environmental, economic and intangible outcomes resulting from the adoption of green supply chain initiatives. This study used a structured questionnaire derived from the literature and employing a mail survey to collect responses form a group of 569 ISO 14001 certified firms in Malaysia. The results of testing the hypotheses that predicted that green supply chain initiatives have positive effect on the outcomes showed that eco-design have significant positive effect on the four types of outcomes (environmental outcomes, economic outcomes, cost reductions, and intangible outcomes). Reverse logistics was found to have significant positive effect on cost reductions only. However, green purchasing was not found to have significant effect on any of the four types of outcome. Through designing environmentally friendly products and taking back products and packaging, business organizations can generate benefits to the environment, in the form of reduced waste and better resource utilization, in addition to economic benefits and cost reductions to the organizations. © 2010 Elsevier B.V. All rights reserved.


Naher H.,Universiti Sains Malaysia | Naher H.,Brac University | Abdullah F.A.,Universiti Sains Malaysia
AIP Advances | Year: 2013

In this article, new (G′G)-expansion method and new generalized (G′G)-expansion method is proposed to generate more general and abundant new exact traveling wave solutions of nonlinear evolution equations. The novelty and advantages of these methods is exemplified by its implementation to the KdV equation. The results emphasize the power of proposed methods in providing distinct solutions of different physical structures in nonlinear science. Moreover, these methods could be more effectively used to deal with higher dimensional and higher order nonlinear evolution equations which frequently arise in many scientific real time application fields. © 2013 Copyright 2013 Author(s). This article is distributed under a Creative Commons Attribution 3.0 Unported License.


Kabilan M.K.,Universiti Sains Malaysia | Khan M.A.,University of Dhaka
Computers and Education | Year: 2012

Assessment in learning is always of interest to practitioners, academics and researchers, and is always evolving with new implications. Alternative forms of assessment such as e-portfolios have gained recognition in documenting students' learning, as it is synchronous with both product and process. Vast amount of literature narrates the relative advantages of e-portfolios across disciplines, institutions, and applications. In Malaysia, such alternative assessment practices are less explored so far in teacher education. In this study, 55 pre-service TESOL teachers from Universiti Sains Malaysia (USM) are required to create and maintain a personal e-portfolio. The aim of the study is to ascertain the future teachers' practices with e-portfolios in their learning and to determine if these practices lead to teaching competencies. In addition, the study also aims to identify the benefits and challenges of using an e-portfolio as a tool for learning and self-assessment. Findings indicate that participants are appreciative of e-portfolios, as their performance and achievements are traced over time. It is also found that e-portfolios function as a monitoring tool, which helps the teachers recognize their learning and identify their strengths and weaknesses. Challenges are also noted, which include validity and reliability, interrupted Internet connection, negative attitudes participants, time constraints, workload and ethical issues. In terms of teacher competencies, it is found that six competencies emerge from the teachers' practices of e-portfolios - (1) developing understanding of an effective teacher's role; (2) developing teaching approaches/activities; (3) improving linguistic abilities; (4) comprehending content knowledge; (5) gaining ICT skills and; (6) the realization of the need to change mindsets. © 2012 Elsevier Ltd. All rights reserved.


Lee Y.Y.,Universiti Sains Malaysia | Mahendra Raj S.,Pantai Hospital Kuala Lumpur | Graham D.Y.,Baylor College of Medicine
Helicobacter | Year: 2013

Helicobacter pylori (H. pylori) infection is etiologically associated with gastric cancer and peptic ulcer diseases which are both important public health burdens which could be largely eliminated by H. pylori eradication. However, some investigators urge caution based on the hypothesis that eradication of H. pylori may result in an increase in the incidence of gastroesophageal reflux disease, esophageal adenocarcinoma, and childhood asthma. The ethnic Malays of northeastern Peninsular Malaysia have long had a low prevalence of H. pylori infection and, as expected, the incidence of gastric cancer and its precursor lesions is exceptionally low. The availability of a population with a low H. pylori prevalence and generally poor sanitation allows separation of H. pylori from the hygiene hypothesis and direct testing of whether absence of H. pylori is associated with untoward consequence. Contrary to predictions, in Malays, erosive esophagitis, Barrett's esophagus, distal esophageal cancers, and childhood asthma are all of low incidence. This suggests that H. pylori is not protective rather the presence of H. pylori infection is likely a surrogate for poor hygiene and not an important source of antigens involved in the hygiene hypothesis. Helicobacter pylori in Malays is related to transmission from H. pylori-infected non-Malay immigrants. The factors responsible for low H. pylori acquisition, transmission, and burden of H. pylori infection in Malays remain unclear and likely involves a combination of environmental, host (gene polymorphisms), and strain virulence factors. Based on evidence from this population, absence of H. pylori infection is more likely to be boon than a bane. © 2013 John Wiley & Sons Ltd.


Uddin M.J.,Universiti Sains Malaysia | Khan W.A.,National University of Sciences and Technology | Ismail A.I.M.,Universiti Sains Malaysia
Transport in Porous Media | Year: 2012

The steady laminar incompressible free convective flow of a nanofluid over a permeable upward facing horizontal plate located in porous medium taking into account the thermal convective boundary condition is studied numerically. The nanofluid model used involves the effect of Brownian motion and the thermophoresis. Using similarity transformations the continuity, the momentum, the energy, and the nanoparticle volume fraction equations are transformed into a set of coupled similarity equations, before being solved numerically, by an implicit finite difference numerical method. Our analysis reveals that for a true similarity solution, the convective heat transfer coefficient related with the hot fluid and the mass transfer velocity must be proportional to x -2/3, where x is the horizontal distance along the plate from the origin. Effects of the various parameters on the dimensionless longitudinal velocity, the temperature, the nanoparticle volume fraction, as well as on the rate of heat transfer and the rate of nanoparticle volume fraction have been presented graphically and discussed. It is found that Lewis number, the Brownian motion, and the convective heat transfer parameters increase the heat transfer rate whilst the thermophoresis decreases the heat transfer rate. It is also found that Lewis number and the convective heat transfer parameter enhance the nanoparticle volume fraction rate whilst the thermophoresis parameter decreases nanoparticle volume fraction rate. A very good agreement is found between numerical results of the present article for special case and published results. This close agreement supports the validity of our analysis and the accuracy of the numerical computations. © 2012 Springer Science+Business Media B.V.


Lee Y.Y.,Universiti Sains Malaysia | Chua A.S.B.,Gastro Center Ipoh
Journal of Neurogastroenterology and Motility | Year: 2013

Despite being a large ethnic group within the South-East Asia, there is a paucity of reported literatures on dyspepsia in the Malay population. Recent population-based studies indicate that uninvestigated dyspepsia, based on the Rome II criteria, is re-ported in 12.8% and 11.6% of Malays in the urban and rural communities respectively. Organic causes of dyspepsia including upper gastrointestinal tract cancers, its precancerous lesions, and erosive diseases are uncommon which is largely due to an exceptionally low prevalence of Helicobacter pylori infection in this population. On the other hand, functional dyspepsia and irritable bowel syndrome are relatively common in the Malays than expected. Within a primary care setting, functional dyspep-sia, based on the Rome III criteria, is reported in 11.9% of Malays, of which epigastric pain syndrome is found to be more common. Married Malay females are more likely to have functional dyspepsia and psychosocial alarm symptoms. Also based on the Rome III criteria, irritable bowel syndrome, commonly overlapped with functional dyspepsia, is reported in 10.9% of Malays within a community-based setting. Rather than psychosocial symptoms, red flags are most likely to be reported among the Malays with irritable bowel syndrome despite having a low yield for organic diseases. Based upon the above observations, "proton pump inhibitor test" is probably preferable than the "test and treat H. pylori" strategy in the initial management of dyspepsia among the Malays. © 2013 The Korean Society of Neurogastroenterology and Motility.


Lee Y.Y.,Universiti Sains Malaysia | Chua A.S.B.,Gastro Center Ipoh
Journal of Neurogastroenterology and Motility | Year: 2012

The diagnosis of functional dyspepsia (FD) is challenging since it depends largely on symptoms which are often heterogeneous and overlapping. This is particularly so in Asia with many different cultures and languages. Symptom-based diagnosis of FD based on Rome III criteria has not been fully validated and it may not be suitable in some Asian populations. Clinicians often assume that investigations in FD are not rewarding and physiological tests are often not available unless in the research setting. Investigation of alarm features and role of Helicobacter pylori in FD remain controversial but experts agreed that both should be tested. Physiological tests including gastric accommodation and chemical hypersensitivity tests are underutilized in Asia and available studies were few. While experts do not recommend routine clinical use of gastric accommodation tests but they agree that these tests can be advocated if clinically indicated. Empiric therapeutic trial is not currently a diagnostic option. The pathogenesis of FD is still poorly understood and there is a substantial placebo response. As a conclusion, a diagnosis of FD is challenging especially so in the context of Asia and despite the limitations of available physiological tests experts agreed that these tests can be advocated if and when clinically indicated. © 2012 The Korean Society of Neurogastroenterology and Motility.


Sin J.-C.,Universiti Sains Malaysia | Lam S.-M.,Universiti Sains Malaysia | Satoshi I.,Osaka University | Lee K.-T.,Universiti Sains Malaysia | Mohamed A.R.,Universiti Sains Malaysia
Applied Catalysis B: Environmental | Year: 2014

Europium-doped ZnO hierarchical micro/nanospheres (Eu/ZnO) were synthesized for the first time via a facile and surfactant-free chemical solution route. The as-synthesized products were characterized by X-ray diffraction, field-emission scanning electron microscopy, energy dispersion X-ray analysis, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, UV-visible diffuse reflectance spectroscopy, nitrogen adsorption-desorption and photoluminescence spectroscopy. The results showed that the as-synthesized products were well-crystalline and accumulated by large amount of interleaving nanosheets. It was also observed that the Eu doping increased the light absorption ability of Eu/ZnO and a red shift for Eu/ZnO appeared when compared to pure ZnO. Under natural sunlight irradiation, the Eu/ZnO exhibited much higher photocatalytic activity than those of pure ZnO, Eu-doped ZnO nanorods (Eu/ZNRs) and commercial TiO2 for the degradation of phenol. The photocatalytic enhancement of Eu/ZnO products was attributed to their high charge separation efficiency and hydroxyl radical generation ability as evidenced by the photoluminescence spectra. By using several radical scavengers, hydroxyl radical was determined to play a pivotal role for the phenol degradation. Furthermore, the Eu/ZnO could be easily separated and reused, showing great potential for practical applications in environmental cleanup and solar energy conversion. © 2013 Elsevier B.V.


Abidi S.S.R.,Dalhousie University | Chong Y.H.,Universiti Sains Malaysia
Lecture Notes in Artificial Intelligence (Subseries of Lecture Notes in Computer Science) | Year: 2014

Constraints formalize the dependencies in a physical world in terms of a logical relation among several unknowns. Constraint satisfaction methods allow efficient navigation of large search spaces to find an optimal solution that satisfies given constraints. This paper explores the application of constraint satisfaction methods to personalize generic information content with respect to a user-model. We present a constraint satisfaction based information personalization framework that (a) generates personalized information via the dynamic selection and synthesis of multiple information-snippets; and (b) ensures that the dynamically adapted personalized information is factually consistent. We present four constraint satisfaction methods that cumulatively work to maximize collaboration and minimize conflicts between a set of information-snippets in order to dynamically generate personalized information. © Springer-Verlag Berlin Heidelberg 2004.


Jadin M.S.,Universiti Malaysia Pahang | Taib S.,Universiti Sains Malaysia
Infrared Physics and Technology | Year: 2012

Infrared thermography (IRT) has gained more attention and become an interesting method in electrical preventive maintenance due to its high precision and sensitivity imaging characteristics. This paper provides a review of the application of IRT for diagnosing electrical equipment, including their thermal anomalies and methods of measurement. Improvement of the inspection techniques is highlighted in order to investigate the reliability of electrical equipments due to the effect of the environmental factors and equipment condition. Factors related to the target equipment and the inspection tool together with their characteristics is also presented. Due to the complex analysis, various automatic diagnostic systems are proposed for faster and more accurate analysis. Typical engineering solutions using recent technologies are reviewed which could be used to improve the quality of IRT inspection. © 2012 Elsevier B.V. All rights reserved.


Citartan M.,Universiti Sains Malaysia | Gopinath S.C.B.,Japan National Institute of Advanced Industrial Science and Technology | Tominaga J.,Japan National Institute of Advanced Industrial Science and Technology | Tang T.-H.,Universiti Sains Malaysia
Analyst | Year: 2013

Reporting biomolecular interactions has become part and parcel of many applications of science towards an in-depth understanding of disease and gene regulation. Apart from that, in diagnostic applications where biomolecules (antibodies and aptamers) are vastly applied, meticulous monitoring of biomolecular interaction is vital for clear-cut diagnosis. Several currently available methods of analyzing the interaction of the ligands with the appropriate analytes are aided by labeling using fluorescence or luminescence techniques. However, labeling is cumbersome and can occupy important binding sites of interactive molecules to be labeled, which may interfere with the conformational changes of the molecules and increase non-specificity. Optical-based sensing can provide an alternative way as a label-free procedure for monitoring biomolecular interactions. Optical sensors affiliated with different operating principles, including surface plasmon changes, scattering and interferometry, can impart a huge impact for in-house and point-of-care applications. This optical-based biosensing permits real-time monitoring, obviating the use of hazardous labeling molecules such as radioactive tags. Herein, label-free ways of reporting biomolecular interactions by various optical biosensors were gleaned.© 2013 The Royal Society of Chemistry.


Omar R.,University Putra Malaysia | Idris A.,University Putra Malaysia | Yunus R.,University Putra Malaysia | Khalid K.,University Putra Malaysia | Aida Isma M.I.,Universiti Sains Malaysia
Fuel | Year: 2011

Agricultural waste such as oil palm empty fruit bunch (EFB) is of environmental concern to Malaysia as one of the world's largest oil palm producers. Pyrolysis can be used to treat biomass waste due to its flexibility in producing solid, liquid and gas products. This study attempts to characterize EFB for pyrolysis using microwaves as an alternative heating source. EFB taken from a local oil palm mill was subjected to fuel, chemical and dielectric property analysis. The findings revealed that high moisture and 47% oxygen gave low calorific value of 16 MJ/kg. Notably, high water content is an advantage in microwave heating as water is a good microwave absorber, which results in fast drying. Further, a high volatile content at 70% gave the EFB an advantage of high reactivity. A moderate potassium content of 12.8% could also positively affect microwave absorption. The dielectric properties of EFB were observed to be proportional to the moisture content. Furthermore, the microwave penetration depth was found highest at 20% moisture, i.e. 3.5 cm. However, low values of both dielectric constant and loss of dried EFBs would require the addition of microwave absorbers for pyrolysis reaction. The fuel and chemical characteristics of EFB were found comparable to other biomasses, which indicated a good candidate for microwave pyrolysis treatment. © 2011 Elsevier Ltd All rights reserved.


Zyoud S.H.,Universiti Sains Malaysia | Al-Jabi S.W.,An Najah National University | Sweileh W.M.,An Najah National University
Human and Experimental Toxicology | Year: 2015

Purpose: There is a lack of data concerning the evaluation of scientific research productivity in paracetamol poisoning from the world. The purposes of this study were to analyse the worldwide research output related to paracetamol poisoning and to examine the authorship pattern and the citations retrieved from the Scopus database forover a decade.Methods: Data were searched for documents with specific words regarding paracetamol poisoning as 'keywords' in the title or/and abstract. Scientific output was evaluated based on a methodology developed and used in other bibliometric studies. Research productivity was adjusted to the national population and nominal gross domestic product (GDP) per capita.Results: There were 1721 publications that met the criteria during study period from the world. All retrieved documents were published from 72 countries. The largest number of articles related to paracetamol poisoning was from the United States (US; 30.39%), followed by India (10.75%) and the United Kingdom (UK; 9.36%). The total number of citations at the time of data analysis was 21,109, with an average of 12.3 citations per each documents and median (interquartile range) of 4 (1-14). The h-index of the retrieved documents was 57. After adjusting for economy and population power, India (124.2), Nigeria (18.6) and the US (10.5) had the highest research productivity. Countries with large economies, such as the UK, Australia, Japan, China and France, tended to rank relatively low after adjustment for GDP over the entire study period.Conclusion: Our study demonstrates evidence that research productivity related to paracetamol poisoning has increased rapidly during the recent years. The US obviously dominated in research productivity. However, certain smaller country such as Nigeria has high scientific output relative to their population size and GDP. A highly noticeable increase in the contributions of Asia-Pacific and Middle East regions to scientific literature related to paracetamol poisoning was also observed. © The Author(s) 2014.


Sobhani F.A.,International Islamic University Chittagong | Amran A.,Universiti Sains Malaysia | Zainuddin Y.,Universiti Malaysia Pahang
Journal of Cleaner Production | Year: 2012

This study aims to describe the status of disclosure practices of corporate sustainability in the annual reports and corporate websites of the banking industry in Bangladesh. It is revealed in the study that, to varying degrees, all listed banks practice sustainability disclosure in an unstructured manner in both the annual reports and corporate websites. The annual report surpasses the corporate website in the disclosure of all categories of corporate sustainability disclosure (CSD) practices except product responsibility disclosure. Unlike the environmental and economic dimensions, issues concerning the social dimension are generally disclosed. Islamic banks disclose more sustainability information in comparison to conventional banks. It is also found that among the three generation, the older bank does not outperform the younger bank in terms of the sustainability disclosure. © 2011 Elsevier Ltd. All rights reserved.


Zyoud S.H.,Universiti Sains Malaysia | Al-Jabi S.W.,Community Pharmacy | Sweileh W.M.,An Najah National University | Awang R.,Universiti Sains Malaysia
Harm Reduction Journal | Year: 2014

Background: Tobacco smoking is the main health-care problem in the world. Evaluation of scientific output in the field of tobacco use has been poorly explored in Middle Eastern Arab (MEA) countries to date, and there are few internationally published reports on research activity in tobacco use. The main objectives of this study were to analyse the research output originating from 13 MEA countries on tobacco fields and to examine the authorship pattern and the citations retrieved from the Scopus database.Methods: Data from 1 January 2003 through 31 December 2012 were searched for documents with specific words regarding the tobacco field as 'keywords' in the title in any 1 of the 13 MEA countries. Research productivity was evaluated based on a methodology developed and used in other bibliometric studies.Results: Five hundred documents were retrieved from 320 peer-reviewed journals. The greatest amount of research activity was from Egypt (25.4%), followed by the Kingdom of Saudi Arabia (KSA) (23.2%), Lebanon (16.3%), and Jordan (14.8%). The total number of citations for the 560 documents, at the time of data analysis (27 August 2013), was 5,585, with a mean ± SD of 9.95 ± 22.64 and a median (interquartile range) of 3(1-10). The h-index of the retrieved documents was 34. This study identified 232 (41.4%) documents from 53 countries in MEA-foreign country collaborations. By region, MEA collaborated most often with countries in the Americas (29.6%), followed by countries in the same MEA region (13.4%), especially KSA and Egypt.Conclusions: The present data reveal a promising rise and a good start for research productivity in the tobacco field in the Arab world. Research output is low in some countries, which can be improved by investing in more international and national collaborative research projects in the field of tobacco. © 2014 Zyoud et al.; licensee BioMed Central Ltd.


Nurfitri I.,Universiti Malaysia Pahang | Maniam G.P.,Universiti Malaysia Pahang | Hindryawati N.,Universiti Malaysia Pahang | Yusoff M.M.,Universiti Malaysia Pahang | Ganesan S.,Universiti Sains Malaysia
Energy Conversion and Management | Year: 2013

For many years, the cost of production has been the main barrier in commercializing biodiesel, globally. It has been well researched and established in the literature that the cost of feedstock is the major contributor. Biodiesel producers are forced to choose between edible and non-edible feedstock. The use of edible feedstock sparks concern in terms of food security while the inedible feedstock needs additional pretreatment steps. On the other hand, the wide availability of edible feedstock guarantees the supply while the choice of non-edible results in a non-continuous or non-ready supply. With these complications in mind, this review attempts to identify possible solutions by exploring the potential of waste edible oils and waste catalysts in biodiesel preparation. Since edible oils are available and used abundantly, waste or used edible oils have the potential to provide plentiful feedstock for biodiesel. In addition, since traditional homogeneous catalysts are less competent in transesterifying waste/used oils, this review includes the possibility of heterogeneous catalysts from waste sources that are able to aid the transesterification reaction with success. © 2013 Elsevier B.V.


Citartan M.,Universiti Sains Malaysia | Gopinath S.C.B.,Japan National Institute of Advanced Industrial Science and Technology | Tominaga J.,Japan National Institute of Advanced Industrial Science and Technology | Tan S.-C.,Universiti Sains Malaysia | Tang T.-H.,Universiti Sains Malaysia
Biosensors and Bioelectronics | Year: 2012

Aptamers are single stranded DNA or RNA oligonucleotides that have high affinity and specificity towards a wide range of target molecules. Aptamers have low molecular weight, amenable to chemical modifications and exhibit stability undeterred by repetitive denaturation and renaturation. Owing to these indispensable advantages, aptamers have been implemented as molecular recognition element as alternative to antibodies in various assays for diagnostics. By amalgamating with a number of methods that can provide information on the aptamer-target complex formation, aptamers have become the elemental tool for numerous biosensor developments. In this review, administration of aptamers in applications involving assays of fluorescence, electrochemistry, nano-label and nano-constructs are discussed. Although detection strategies are different for various aptamer-based assays, the core of the design strategies is similar towards reporting the presence of specific target binding to the corresponding aptamers. It is prognosticated that aptamers will find even broader applications with the development of new methods of transducing aptamer target binding. © 2012 Elsevier B.V.


Zyoud S.H.,Universiti Sains Malaysia | Al-Jabi S.W.,Community Pharmacy | Sweileh W.M.,An Najah National University
Tobacco Induced Diseases | Year: 2014

Background: Waterpipe tobacco smoking has spread worldwide. However, the evaluation of scientific output in the field of waterpipe tobacco smoking has not been studied yet. The main objectives of this study were to analyze worldwide research output in the waterpipe tobacco smoking field, and to examine the authorship pattern and the citations retrieved from the Scopus database for over a decade. Methods. Data from January 1, 2003 through December 31, 2012 were searched for documents with specific words regarding waterpipe tobacco smoking as "keywords" in the title. Scientific output was evaluated based on a methodology developed and used in other bibliometric studies: (a) total and trends of contributions in waterpipe tobacco smoking research between 2003 and 2012; (b) authorship patterns and research productivity; (c) collaboration patterns; (d) the citations received by the publications; and (e) areas of interest of the published papers. Results: Worldwide there were 334 publications that met the criteria during the study period. The largest number of publications in waterpipe tobacco smoking were from the United States of America (USA) (33.5%), followed by Lebanon (15.3%), and France (10.5%). The total number of citations at the time of data analysis (October 18, 2013) was 4,352, with an average of 13 citations per document and a median (interquartile range) of 4.0 (1.0-16.0). The h-index of the retrieved documents was 34. The highest h-index by country was 27 for the USA, followed by 20 for Syrian Arab Republic and Lebanon. Conclusions: The present data reveal a promising rise and a good start for research activity in the field of waterpipe tobacco smoking. More effort is needed to bridge the gap in waterpipe smoking-based research and to promote better evaluation of waterpipe smoking, risks, health effects, or control services worldwide. © 2014 Zyoud et al.; licensee BioMed Central Ltd.


Zyoud S.H.,Universiti Sains Malaysia | Al-Jabi S.W.,Community Pharmacy | Sweileh W.M.,An Najah National University
BMC Public Health | Year: 2014

Background: Electronic cigarette (EC) is an emerging phenomenon that is becoming increasingly popular with smokers worldwide. There is a lack of data concerning the evaluation of research productivity in the field of EC originating from the world. The main objectives of this study were to analyse worldwide research output in EC field, and to examine the authorship pattern and the citations retrieved from the Scopus database. Methods. Data were searched for documents with specific words regarding EC as "keywords" in the title. Scientific output was evaluated based on the methodology developed and used in other bibliometric studies by investigation: (a) total and trends of contributions in EC research during all previous years up to the date of data analysis (June 13, 2014); (b) authorship patterns and research productivity; (c) countries contribution; and (d) citations received by the publications. Results: Three hundred and fifty-six documents were retrieved comprising 31.5% original journal articles, 16% letters to the editor, 7.9% review articles, and 44.6% documents that were classified as other types of publications, such as notes or editorials or opinions. The retrieved documents were published in 162 peer-reviewed journals. All retrieved documents were published from 27 countries. the largest number of publications in the field of EC was from the United States of America (USA); (33.7%), followed by the United Kingdom (UK); (11.5%), and Italy (8.1%). The total number of citations at the time of data analysis was 2.277, with an average of 6.4 citations per document and median (interquartile range) of 0.0 (0.0-5.0). The h-index of the retrieved documents was 27. The most productive institutions were Food and Drug Administration, USA (4.2% of total publications) followed by Universita degli Studi di Catania, Italy (3.9%), University of California, San Francisco, USA (3.7%). Conclusions: This bibliometric study is a testament to the progress in EC research from the world over the last few years. More effort is needed to bridge the gap in EC-based research and to promote better evaluation of EC, risks, health effects, or control services worldwide. © 2014 Zyoud et al.; licensee BioMed Central Ltd.


Lok Y.Y.,Universiti Sains Malaysia | Pop I.,Babes - Bolyai University
Meccanica | Year: 2014

A detailed study of the problem of unsteady separated stagnation-point flow toward a stretching or shrinking sheet is presented. By use of a similarity transformation, the partial differential equations are reduced to a system of ordinary differential equations which are then solved numerically by use of the collocation method. The bvp4c Matlab program is used to perform the computation. This method is capable of finding multiple solutions for the flow reattachment case. The streamlines of the separation flow are presented for the cases when the origins of the stagnation flow and the stretching sheet are aligned and non-aligned. Comparison with results from the open literature reveals excellent agreement. © Springer Science+Business Media Dordrecht 2014.


Mirjalili F.,University Putra Malaysia | Hasmaliza M.,Universiti Sains Malaysia | Abdullah L.C.,University Putra Malaysia
Ceramics International | Year: 2010

Nano α-alumina particles were synthesized by a sol-gel method using aqueous solutions of aluminum isopropoxide and 0.5 M aluminum nitrate. 1/3-benzened disoulfonic acid disodium salt (SDBS) and sodium bis-2-ethylhexyl sulfosuccinate (Na(AOT)) were used as surfactant stabilizing agents. Solution was stirred for different periods (24, 36, 48 and 60 h) at 60 °C. The samples were then analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Introduction of surfactant stabilizing agents and different stirring times will affect the size and shape of particle formed and also the degree of aggregation. SDBS, however, produced better dispersion, finer particles and spherical shape nanoparticles, compared to Na(AOT). The finest particle size (20-30 nm) was obtained at 48 h stirring time with SDBS surfactant. © 2010 Elsevier Ltd and Techna Group S.r.l.


Tan C.J.,Universiti Sains Malaysia | Lim C.P.,Deakin University | Cheah Y.,Universiti Sains Malaysia
Neurocomputing | Year: 2014

In this paper, we propose a new multi-objective evolutionary algorithm-based ensemble optimizer coupled with neural network models for undertaking feature selection and classification problems. Specifically, the Modified micro Genetic Algorithm (MmGA) is used to form the ensemble optimizer. The aim of the MmGA-based ensemble optimizer is two-fold, i.e. to select a small number of input features for classification and to improve the classification performances of neural network models. To evaluate the effectiveness of the proposed system, a number of benchmark problems are first used, and the results are compared with those from other methods. The applicability of the proposed system to a human motion detection and classification task is then evaluated. The outcome positively demonstrates that the proposed MmGA-based ensemble optimizer is able to improve the classification performances of neural network models with a smaller number of input features. © 2013 Elsevier B.V.


Ahmad S.,Universiti Sains Malaysia | Pop I.,Babes - Bolyai University
Transport in Porous Media | Year: 2014

The effect of melting phenomenon on the steady mixed convection boundary layer flow about a vertical surface embedded in a fluid-saturated porous medium is numerically studied. The boundary layer partial differential equations are transformed into a set of nonlinear ordinary differential equations by using similarity transformation and then are solved using the shooting method for different values of the mixed convection and melting parameters. Results show that dual solutions exist for a certain range of these parameters. The results also indicate that the melting phenomenon reduces the heat transfer rate and expedites the boundary layer separation. © 2014 Springer Science+Business Media Dordrecht.


Zyoud S.H.,Universiti Sains Malaysia | Al-Jabi S.W.,Community Pharmacy | Sweileh W.M.,An Najah National University | Awang R.,Universiti Sains Malaysia
Health Research Policy and Systems | Year: 2014

Background: Bibliometric studies are increasingly being used for research assessment by involving the application of statistical methods to scientific publications to obtain the bibliographics for each country. The main objective of this study was to analyse the research productivity originating from 13 Middle Eastern Arab (MEA) countries with articles published in toxicology journals.Methods: Data from January 1, 2003 till December 31, 2012 were searched for documents with specific words in the toxicology field as a " source title" in any one of the 13 MEA countries. Research productivity was evaluated based on a methodology developed and used in other bibliometric studies. Research productivity was adjusted to the national population and nominal gross domestic product (GDP) per capita.Results: Documents (n = 1,240) were retrieved from 73 international peer-reviewed toxicology journals. The h-index of the retrieved documents was 39. Of the 73 journal titles, 52 (69.9%) have their IF listed in the ISI Journal Citation Reports 2012; 198 documents (16.0%) were published in journals that had no official IF. After adjusting for economy and population power, Egypt (193.6), Palestine (18.1), Kingdom of Saudi Arabia (KSA) (13.0), and Jordan (11.5) had the highest research productivity. Countries with large economies, such as the Kuwait, United Arab Emirates (UAE), and Oman, tended to rank relatively low after adjustment of GDP. The total number of citations at the time of data analysis (August 4, 2013) was 10,991, with a median (interquartile range) of 4 (1-11). MEA collaborated more with countries in the MEA regions (16.7%), especially KSA, Egypt, and UAE, followed by Europe (14.4%), especially with the United Kingdom and Germany.Conclusions: The present data show a promising rise and a good start for toxicology research activity in toxicology journals in the Arab world. Research output is low in some countries, which can be improved by investing in more international and national collaborative research projects in the field of toxicology. © 2014 Zyoud et al.; licensee BioMed Central Ltd.


Aljumah K.,Al Amal Psychiatric Hospital | Hassali A.A.,Universiti Sains Malaysia | AlQhatani S.,Al Amal Psychiatric Hospital
Neuropsychiatric Disease and Treatment | Year: 2014

Background: Adherence to antidepressant treatment is an essential step in the management of patients with major depressive disorder, and several factors can contribute to antidepressant nonadherence. Evidence supports the hypothesis that patient treatment satisfaction will result in improved adherence; therefore, the aim of this study was to investigate the relationship between patient treatment satisfaction and adherence to antidepressants, and the role of patient beliefs toward medication in patient treatment satisfaction. Methods: This was an observational, nonexperimental survey of all patients attending Al Amal Psychiatric Hospital (500 beds) in Riyadh, Saudi Arabia. Medication adherence was assessed using the eight-item Morisky Medication Adherence Scale (MMAS-8), and treatment satisfaction was assessed using the Treatment Satisfaction Questionnaire for Medication (TSQM 1.4). Results: A total of 403 patients met the inclusion criteria; 50.4% were females; participant age ranged from 18 to 60 years; and 16 % of the patients reported side effects after using antidepressants. Both males and females reported high treatment satisfaction rates: - 79.21% (standard deviation [SD] 8.52) and 86.55% (SD 14.34), respectively - with statistically significant associations found for female sex, older age, and three or more physician visits per year. Adherence to antidepressants was associated with treatment satisfaction with the antidepressants, with a direct positive correlation. Conclusion: The results of this study showed high treatment satisfaction scores among patients in Saudi Arabia with major depressive disorder, which correlated with adherence and patient beliefs about the necessity of treatment. This finding has improved the understanding of the role of patient beliefs, which can help caregivers and other stakeholders to improve satisfaction with antidepressants. © 2014 Aljumah et al.


Al-Samarraie H.,Universiti Sains Malaysia | Teo T.,University of Auckland | Abbas M.,Universiti Sains Malaysia
Computers and Education | Year: 2013

This paper proposes an e-learning model to assess the effects of online structured representation of content on learners' understanding. We designed a structured representation based on the theory of distributed cognition that provides seven segments for reading research articles. The study hypothesized that motivation, attention, and interactivity are essential factors that affect students' thinking skills for understanding e-learning content. To investigate and confirm the effect of these factors on the students' thinking skills, we designed a survey and analyzed the responses of 210 university students concerning the proposed structured representation. The results revealed that motivation, attention, and interactivity did contribute to the students' thinking skills. They also demonstrated that the structured representation helped students achieve an adequate level of thinking skills as they read research articles, which had a positive effect on their understanding. This finding demonstrates that structured representation has significant potential as a learning tool and that structure-based e-learning can influence students' metacognitive activities and facilitate their understanding. © 2013 Elsevier Ltd. All rights reserved.


Aljumah K.,Al Amal Psychiatric Hospital | Hassali M.A.,Universiti Sains Malaysia
BMC Psychiatry | Year: 2015

Background: Adherence to antidepressant treatment is essential for the effective management of patients with major depressive disorder. Adherence to medication is a dynamic decision-making process, and pharmacists play an important role in improving adherence to antidepressant treatment in different settings within the healthcare system. The aim of this study was to assess whether pharmacist interventions based on shared decision making improved adherence and patient-related outcomes. Methods: This was a randomised controlled study with a 6-month follow-up. Participants were randomly allocated to two groups: 1) intervention group (IG) (usual pharmacy services plus pharmacist interventions based on shared decision making); or 2) control group (CG) (usual pharmacy services). Recruited patients fulfilled the following inclusion criteria: aged 18 to 60 years diagnosed with a major depressive disorder, and no history of psychosis or bipolar disorders. A research assistant blinded to the group allocations collected all data. Results: Two hundred and thirty-nine patients met the inclusion criteria and were randomised to the IG (n = 119) or CG (n = 120). Nineteen patients dropped out of the study during the follow-up phase. After 6 months, patients in the IG had significantly more favorable medication adherence, treatment satisfaction, general overuse beliefs, and specific concern beliefs. However, the groups did not differ in severitye of depression or health-related quality of life after 6 months. Conclusions: Our findings emphasise the important role of pharmacists in providing direct patient care in regular pharmacy practice to improve adherence to medications and other patient-reported outcomes. © 2015 Aljumah and Hassali.


Chan K.W.,Universiti Sains Malaysia | McCulloch M.,University of Oxford
International Journal of Refrigeration | Year: 2013

Bubble pump (BP), an essential component in coffee percolators, is used to drive solar water heating systems and single pressure absorption refrigerators. However, its mass flow rate cannot be readily predicted. Heat input, tube diameter and submergence ratio affect its mass flow rate. BP has the same working concept as air-lift pump, but its flow is complicated due to the condensation of vapour bubbles. Neither curve fitting models, nor air-lift pump models, can predict the mass flow rate with high fidelity. A new model based on the pumping characteristics of BP is presented and verified by a water based setup at atmospheric pressure. Results show that the average errors for the BP with tube diameter of 6-12 mm, and for the BP with submergence ratio of 0.5-0.8 are 13% and 11%, respectively. The BP performance increases when the tube diameter decreases or the submergence ratio increases. © 2013 Elsevier Ltd and IIR. All rights reserved.


Al-Heuseen K.,Universiti Sains Malaysia | Hashim M.R.,Universiti Sains Malaysia | Ali N.K.,University of Technology Malaysia
Applied Surface Science | Year: 2011

This article reports the properties and the behavior of GaN during the photoelectrochemical etching process using four different electrolytes. The measurements show that the porosity strongly depends on the electrolyte and highly affects the surface morphology of etched samples, which has been revealed by scanning electron microscopy (SEM) images. Peak intensity of the photoluminescence (PL) spectra of the porous GaN samples was observed to be enhanced and strongly depend on the electrolytes. Among the samples, there is a little difference in the peak position indicating that the change of porosity has little influence on the PL peak shift, while it highly affecting the peak intensity. Raman spectra of porous GaN under four different solution exhibit phonon mode E2 (high), A1 (LO), A1 (TO) and E2 (low). There was a red shift in E2 (high) in all samples, indicating a relaxation of stress in the porous GaN surface with respect to the underlying single crystalline epitaxial GaN. Raman and PL intensities were high for samples etched in H2SO4:H 2O2 and KOH followed by the samples etched in HF:HNO 3 and in HF:C2H5OH. © 2011 Elsevier B.V. All rights reserved.


Lee Y.Y.,University of Glasgow | Lee Y.Y.,Universiti Sains Malaysia | Derakhshan M.H.,University of Glasgow
Archives of Iranian Medicine | Year: 2013

Effective prevention and early diagnostic strategies are the most important public health interventions in gastric cancer, which remains a common malignancy worldwide. Preventive strategies require identification and understanding of environmental risk factors that lead to carcinogenesis. Helicobacter pylori (H. pylori) is the primary carcinogen as this ancient bacterium has a complex ability to interact with its human host. Smoking and salt are strong independent risk factors for gastric cancer whereas alcohol is only a risk when it is heavily consumed. Red meat and high fat increase the risk of gastric cancer however fresh fruits, vegetables (allium family) and certain micronutrients (selenium, vitamin C) reduce the risk, with evidence lacking for fish, coffee and tea. Foods that inhibit H. pylori viability, colonization and infection may reduce cancer risk. Obesity is increasingly recognized as a contributory factor in gastric cardia carcinogenesis. Therefore, modest daily physical activities can be protective against cancer. Foundry workers are at risk for developing gastric cancer with dust iron being an important cause. Other risk factors include Epstein-Barr virus (EBV), possibly JC virus and radiation but the effects of these are likely to remain small.


Yee K.F.,Universiti Sains Malaysia | Lee K.T.,Universiti Sains Malaysia | Ceccato R.,University of Trento | Abdullah A.Z.,Universiti Sains Malaysia
Bioresource Technology | Year: 2011

This study reports the conversion of Jatropha curcas L. oil to biodiesel catalyzed by sulfated zirconia loaded on alumina catalyst using response surface methodology (RSM), specifically to study the effect of interaction between process variables on the yield of biodiesel. The transesterification process variables studied were reaction temperature, reaction duration, molar ratio of methanol to oil and catalyst loading. Results from this study revealed that individual as well as interaction between variables significantly affect the yield of biodiesel. With this information, it was found that 4. h of reaction at 150 °C, methanol to oil molar ratio of 9.88. mol/mol and 7.61 wt.% for catalyst loading gave an optimum biodiesel yield of 90.32 wt.%. The fuel properties of Jatropha biodiesel were characterized and it indeed met the specification for biodiesel according to ASTM D6751. © 2010 Elsevier Ltd.


Bhat R.,Universiti Sains Malaysia | Rai R.V.,University of Mysore | Karim A.A.,Universiti Sains Malaysia
Comprehensive Reviews in Food Science and Food Safety | Year: 2010

Disease outbreaks due to the consumption of contaminated food and feedstuff are a recurring problem worldwide. The major factor contributing to contamination are microorganisms, especially fungi, which produce low-molecular-weight compounds as secondary metabolites, with confirmed toxic properties referred to as mycotoxins. Several mycotoxins reported to date are cosmopolitan in distribution and incur severe health-associated risks (including cancer and neurological disorders). Hence, creating awareness among consumers, as well as developing new methods for detection and inactivation is of great importance for food safety. In this review, the focus is on the occurrence of various types of mycotoxins in food and feed associated with risks to humans and livestock, as well as legislation put forth by various authorities, and on presently practiced detoxification methods. Brief descriptions on recent developments in mycotoxin detection methodology are also inlcuded. This review is meant to be informative not only for health-conscious consumers but also for experts in the field to pave the way for future research to fill the existing gaps in our knowledge with regard to mycotoxins and food safety. © 2010 Institute of Food Technologists®.


Jawaid M.,University of Technology Malaysia | Abdul Khalil H.P.S.,Universiti Sains Malaysia | Hassan A.,University of Technology Malaysia | Dungani R.,Bandung Institute of Technology | Hadiyane A.,Bandung Institute of Technology
Composites Part B: Engineering | Year: 2013

Hybrid composites prepared by hand lay-up technique by reinforcing jute and oil palm fibres with epoxy matrix. The tensile properties of hybrid composites were found to increase substantially with increasing jute fibres loading as compared to oil palm-epoxy composite. The nature of fibre/matrix interface was examined through scanning electron microscopy of tensile fracture samples. Addition of jute fibres to oil palm composite increases the storage modulus while damping factor shifts towards higher temperature region. Cole-Cole analysis was made to understand the phase behaviour of the composite samples. The hybrid composite with oil palm:jute (1:4) showed maximum damping behaviour and highest tensile properties. The overall use of hybrid system was found to be effective in increasing tensile and dynamic mechanical properties of the oil palm-epoxy composite probably due to the enhanced fibre/matrix interface bonding. The potential applications of the oil palm based hybrid composites in automobiles and building industry are going to increase in near future. © 2012 Elsevier Ltd. All rights reserved.


Singh D.,Universiti Sains Malaysia | Muller C.P.,Friedrich - Alexander - University, Erlangen - Nuremberg | Vicknasingam B.K.,Universiti Sains Malaysia
Drug and Alcohol Dependence | Year: 2014

Background: Kratom (Mitragyna speciosa) preparations have been traditionally used in Southeast Asia for its medicinal properties. Lately, Kratom use has spread to Europe and the US, where abuse potential and health hazards increasingly emerge. This study is the first to measure systematically Kratom dependence, withdrawal symptoms, and drug craving in regular Kratom users in Malaysia. Methods: A cross-sectional survey of 293 regular Kratom users was conducted in the community across three northern peninsular states of Malaysia. The Leeds Dependence Questionnaire, Marijuana Withdrawal Checklist, and Marijuana Craving Questionnaire-Short Form were used to measure Kratom dependence, withdrawal and craving. Results: More than half of the regular users (>6 month of use) developed severe Kratom dependence problems, while 45% showed a moderate Kratom dependence. Physical withdrawal symptoms commonly experienced include muscle spasms and pain, sleeping difficulty, watery eyes/nose, hot flashes, fever, decreased appetite, and diarrhoea. Psychological withdrawal symptoms commonly reported were restlessness, tension, anger, sadness, and nervousness. The average amount of the psychoactive compound, mitragynine, in a single dose of a Kratom drink was 79. mg, suggesting an average daily intake of 276.5. mg. Regular users who consumed ≥3 glasses Kratom per day, had higher odds of developing severe Kratom dependence, withdrawal symptoms, and inability to control Kratom craving. Conclusions: The findings from this study show that regular Kratom use is associated with drug dependency, development of withdrawal symptoms, and craving. These symptoms become more severe with prolonged use and suggest a stronger control of the drug. © 2014 Elsevier Ireland Ltd.


Al-Mulali U.,University of Technology Malaysia | Fereidouni H.G.,University of Technology Malaysia | Lee J.Y.,University of Technology Malaysia | Sab C.N.B.C.,Universiti Sains Malaysia
Renewable and Sustainable Energy Reviews | Year: 2013

The bi-directional long run relationship between renewable energy consumption and GDP growth has been investigated in high income, upper middle income, lower middle income, and high income countries. To achieve this goal, the fully modified OLS was utilized. The results revealed that 79% of the countries have a positive bi-directional long run relationship between renewable energy consumption and GDP growth. This represents the feedback hypothesis. On the other hand, 19% of the countries showed no long run relationship between the variables. This represents the neutrality hypothesis. Besides, 2% of the countries showed a one way long run relationship from GDP growth to renewable energy consumption, confirming the conservation hypothesis, and from renewable energy consumption and GDP growth representing the growth hypothesis. Despite the mixed results across countries, it has been proved that the more persistent and significant the bi-directional long run relationship between the variables is, the higher the income countries are. © 2013 Elsevier Ltd.


Mahalingam K.,Indian Institute of Technology Madras | Subramanian K.G.,Universiti Sains Malaysia
International Journal of Foundations of Computer Science | Year: 2012

The Parikh vector of a word enumerates the symbols of the alphabet that occur in the word. The Parikh matrix of a word which has been recently introduced, is an extension of the notion of Parikh vector and gives more numerical information about the word in terms of certain subwords. Intensive investigation on various theoretical properties of Parikh matrices has taken place. This paper deals with the problem of finding properties of words so that their Parikh matrices commute. © 2012 World Scientific Publishing Company.


Wong W.P.,Universiti Sains Malaysia | Wong K.Y.,University of Technology Malaysia
Journal of Cleaner Production | Year: 2014

The concept of lean is important to sustain operations management. Workers are treated as important assets in lean. In this study, a 'lean-ecosphere' management system is developed for a manufacturing company by using interpretive structural modeling (ISM) and analytical network process (ANP). In the first phase of the methodology, a unified index to set a common objective of people is developed for horizontal integration. In the second phase, a hierarchical relationship model is developed to identify relationships between challenges of lean. This model facilitates the building of a strong foundation of lean to promote the depth of human integration. In the end, the results achieved are compared with the current situation of the company. The results indicated that the scientific methodology for lean management system is very beneficial for the company. This paper adds knowledge to the operations management literature by addressing the human resource factor to create a sustainable operation. © 2014 Elsevier Ltd. All rights reserved.


Kuah C.T.,University of Technology Malaysia | Wong K.Y.,University of Technology Malaysia | Wong W.P.,Universiti Sains Malaysia
Expert Systems with Applications | Year: 2012

The paper targets to devise a genuine Knowledge Management (KM) performance measurement model in a stochastic setting based on Data Envelopment Analysis (DEA), Monte Carlo simulation and Genetic Algorithm (GA). The proposed model evaluates KM using a set of proxy measures correlated with the major KM processes. Data Collection Budget Allocation (DCBA) that maximizes the model accuracy is determined using GA. Additional data are generated and analyzed using a Monte-Carlo-enhanced DEA model to obtain the overall KM efficiency and KM processes' efficiency scores. An application of the model has been carried out to evaluate KM performance in higher educational institutions. It is found that with GA, the accuracy of the model has been greatly improved. Lastly, comparing with a conventional deterministic DEA model, the results from the proposed model would be more useful for managers to determine future strategies to improve their KM. © 2012 Elsevier Ltd. All rights reserved.


Qamaruz-Zaman N.,Universiti Sains Malaysia | Milke M.W.,University of Canterbury
Waste Management | Year: 2012

Research was conducted to determine suitable chemical parameters as indicators of odor from decomposing food wastes. Prepared food scraps were stored in 18. l plastic buckets (2. kg wet weight each) at 20. °C and 8. °C to reproduce high and low temperature conditions. After 1, 3, 7, 10 and 14. days of storage, the odor from the buckets were marked to an intensity scale of 0 (no odor) to 5 (intense) and the corresponding leachate analyzed for volatile fatty acids, ammonia and total organic carbon. A linear relationship between odor intensity and the measured parameter indicates a suitable odor indicator. Odor intensified with longer storage period and warmer surroundings. The study found ammonia and isovaleric acid to be promising odor indicators. For this food waste mixture, offensive odors were emitted if the ammonia and isovaleric acid contents exceeded 360. mg/l and 940. mg/l, respectively. © 2012 Elsevier Ltd.


Iq K.C.,Universiti Sains Malaysia | Shu-Chien A.C.,Universiti Sains Malaysia | Shu-Chien A.C.,Malaysian Institute of Pharmaceuticals and Nutraceuticals
PLoS ONE | Year: 2011

Mouthbrooding is an elaborate form of parental care displayed by many teleost species. While the direct benefits of mouthbrooding such as protection and transportation of offsprings are known, it is unclear if mouthbrooding offers additional benefits to embryos during incubation. In addition, mouthbrooding could incur negative costs on parental fish, due to limited feeding opportunities. Parental tilapia fish (Oreochromis spp.) display an elaborated form of parental care by incubating newly hatched embryos in oral buccal cavity until the complete adsorption of yolk sac. In order to understand the functional aspects of mouthbrooding, we undertake a proteomics approach to compare oral mucus sampled from mouthbrooders and non-mouthbrooders, respectively. Majority of the identified proteins have also been previously identified in other biological fluids or mucus-rich organs in different organisms. We also showed the upregulation of 22 proteins and down regulation of 3 proteins in mucus collected from mouthbrooders. Anterior gradient protein, hemoglobin beta-A chain and alpha-2 globin levels were lower in mouthbrooder samples. Mouthbrooder oral mucus collectively showed increase levels of proteins related to cytoskeletal properties, glycolytic pathway and mediation of oxidative stress. Overall the findings suggest cellular stress response, probably to support production of mucus during mouthbrooding phase. © 2011 Iq, Shu-Chien.


Al-Mulali U.,University of Technology Malaysia | Fereidouni H.G.,University of Technology Malaysia | Lee J.Y.M.,University of Technology Malaysia | Sab C.N.B.C.,Universiti Sains Malaysia
Renewable and Sustainable Energy Reviews | Year: 2013

This study explored the relationship between urbanization, energy consumption, and CO2 emission in the MENA countries. The panel model was utilized taking the period 1980-2009 into consideration. Pedroni cointegration test results showed that urbanization, energy consumption and CO2 emission were cointegrated. The dynamic OLS results also showed that there was a long run bi-directional positive relationship between urbanization, energy consumption, and CO2 emission. However, the significance of the long run relationship between urbanization, energy consumption, and CO2 emission varied across the countries based on their level of income and development. Moreover, long and short run bi-directional causal relationships were found between the variables based on the Granger causality test results. From the results of this study it is important for the urban planners and policy makers in the MENA countries to slow the rapid increase in urbanization. The level of energy consumption and CO 2 emission in the MENA countries increased more than double. Thus slowing down the urbanization level can help reduce the level of pollution and energy consumption. In addition, the increased energy efficiency, implementation of energy savings projects, energy conservation, and energy infrastructure outsourcing reduce the level of pollution produced by urban areas. © 2013 Elsevier Ltd.


Kuah M.-K.,Malaysian Institute of Pharmaceuticals and Nutraceuticals | Jaya-Ram A.,Universiti Sains Malaysia | Shu-Chien A.C.,Universiti Sains Malaysia
Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids | Year: 2015

The endogenous production of long-chain polyunsaturated fatty acids (LC-PUFA) in carnivorous teleost species inhabiting freshwater environments is poorly understood. Although a predatory lifestyle could potentially supply sufficient LC-PUFA to satisfy the requirements of these species, the nutrient-poor characteristics of the freshwater food web could impede this advantage. In this study, we report the cloning and functional characterisation of an elongase enzyme in the LC-PUFA biosynthesis pathway from striped snakehead (Channa striata), which is a strict freshwater piscivore that shows high deposition of LC-PUFA in its flesh.Wealso functionally characterised a previously isolated fatty acyl desaturase cDNA from this species. Results showed that the striped snakehead desaturase is capable of Δ4 and Δ5 desaturation activities, while the elongase showed the characteristics of Elovl5 elongases. Collectively, these findings reveal that striped snakehead exhibits the genetic resources to synthesise docosahexaenoic acid (DHA; 22:6n-3) from eicosapentaenoic acid (EPA; 20:5n-3). Both genes are expressed at considerable levels in the brain and the liver. In liver, both genes were up-regulated by dietary C18 PUFA, although this increase did not correspond to a significant rise in the deposition of muscle LC-PUFA. Brain tissue of fish fed with plant oil diets showed higher expression of fads2 gene compared to fish fed with fish oil-based diet, which could ensure DHA levels remain constant under limited dietary DHA intake. This suggests the importance of DHA production from EPA via the Δ4 desaturation step in order to maintain an optimal reserve of DHA in the neuronal tissues of carnivores. © 2014 Elsevier B.V. All rights reserved.


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.


Goswami S.,Bengal Engineering and Science University | Sen D.,Bengal Engineering and Science University | Das N.K.,Bengal Engineering and Science University | Fun H.-K.,Universiti Sains Malaysia | Quah C.K.,Universiti Sains Malaysia
Chemical Communications | Year: 2011

A new fluorescence rhodamine derivative bearing an 8-aminoquinoline moiety has been designed and synthesized for selective sensing of Pd 2+ in the presence of other competing metal ions in aqueous media. Pd 2+ induced spirolactam ring opening of rhodamine is confirmed for the first time by the X-ray crystal structure of the bound Pd 2+-complex. © 2011 The Royal Society of Chemistry.


Najafzadeh M.,Shahid Chamran University | Azamathulla H.M.,Universiti Sains Malaysia
Journal of Computing in Civil Engineering | Year: 2015

In this paper, the neuro-fuzzy based group method of data handling (NF-GMDH) as an adaptive learning network was used to predict the scour process at pile groups due to waves. The NF-GMDH network was developed using the particle swarm optimization (PSO) algorithm and gravitational search algorithm (GSA). Effective parameters on the scour depth include sediment size, geometric property, pile spacing, arrangement of pile group, and wave characteristics upstream of group piles. Seven dimensionless parameters were obtained to define a functional relationship between input and output variables. Published data were compiled from the literature for the scour depth modeling due to waves. The efficiency of training stages for both NF-GMDH-PSO and NF-GMDH-GSA models were investigated. The results indicated that NF-GMDH models could provide more accurate predictions than those obtained using model tree and traditional equations. © 2014 American Society of Civil Engineers.


Jawaid M.,Universiti Sains Malaysia | Abdul Khalil H.P.S.,Universiti Sains Malaysia | Alattas O.S.,King Saud University
Composites Part A: Applied Science and Manufacturing | Year: 2012

The dynamic mechanical and thermal analysis of oil palm empty fruit bunch (EFB)/woven jute fibre (J w) reinforced epoxy hybrid composites were carried out. The storage modulus (E′) was found to decrease with temperature in all cases, and hybrid composites had showed better values of E′ at glass transition temperature (T g) compared to EFB and epoxy. Loss modulus showed shifts in the T g of the polymer matrix with the addition of fibre as reinforcing phase, which indicate that fibre plays an important role in case of T g. The Tan δ peak height was minimum for jute composites and maximum for epoxy matrix. Complex modulus variations and phase behaviour of the hybrid composites was studied by Cole-Cole analysis. Thermal analysis result indicates an increase in thermal stability of EFB composite with the incorporation of woven jute fibres. Hybridization of EFB composite with J w fibres enhanced the dynamic mechanical and thermal properties. © 2011 Elsevier Ltd. All rights reserved.


Chong H.L.H.,Universiti Malaysia Sabah | Chia P.S.,Universiti Malaysia Sabah | Ahmad M.N.,Universiti Sains Malaysia
Bioresource Technology | Year: 2013

Oil palm shell, a waste from palm oil industry, was cleaned and utilized as adsorbent. Its particle size distribution gave the uniformity coefficient of approximately two indicating that it can be used as filter bed media for continuous operation without resting. Its measured pHpzc of 4.1 is below the common pH of constructed wetland water body suggesting positive adsorption for heavy metal. The effect of various parameters on its adsorption was studied via batch experiments. The adsorption of Cu(II) and Pb(II) ions by oil palm shell showed a slightly better fit with the Freundlich compared to Langmuir. Its monolayer adsorption capacities were found to be 1.756 and 3.390mg/g for Cu(II) and Pb(II), respectively. High correlation coefficient of over 0.99 given by the pseudo-second-order model suggests that the rate limiting factor may be chemisorption. These findings suggest its potential application as constructed wetland media for the removal of heavy metal. © 2012 Elsevier Ltd.


Suki N.M.,Universiti Malaysia Sabah | Ramayah T.,Universiti Sains Malaysia
Interdisciplinary Journal of Information, Knowledge, and Management | Year: 2010

This paper identifies the factors that determine users' acceptance of e-Government services and its causal relationships using a theoretical model based on the Technology Acceptance Model. Data relating to the constructs were collected from 200 respondents in Malaysia and subjected to Structural Equation Modeling analysis. The proposed model fits the data well. Results indicate that the important determinants of user acceptance of the e-Government services are perceived usefulness, ease of use, compatibility, interpersonal influence, external influence, self efficacy, facilitating conditions, attitude, subjective norms, perceived behavioral control, and intention to use e-Government services/system. Finally, implications and recommendations of these finding are discussed.


Atabani A.E.,University of Malaya | Mahlia T.M.I.,University of Tenaga Nasional | Anjum Badruddin I.,University of Malaya | Masjuki H.H.,University of Malaya | And 2 more authors.
Renewable and Sustainable Energy Reviews | Year: 2013

Recently, non-edible vegetable oils have been considered as prospective feedstocks for biodiesel production. This is mainly attributed to their ability to overcome the problems of food versus fuel crisis related to edible oils. Globally, there are more than 350 oil-bearing crops identified as potential sources for biodiesel production. The evaluation of the physical and chemical properties of non-edible feedstocks is very important to assess their viability for future biodiesel production. Therefore, this paper aims to study the properties of some potential non-edible feedstocks. Moreover, the paper studies the physical and chemical properties of these promising crops and compares them with other edible oils. These oils include: crude Calophyllum inophyllum L. (CCIO), Jatropha curcas L. (CJCO), Sterculia foetida L. (CSFO), Croton megalocarpus L. (CCMO), Moringa oleifera L. (CMOO), patchouli (CPO), coconut (CCO), palm (CPaO), canola (CCaO), soybean (CSO) and Pangim edule (CPEO) oils. 14 Different properties have been determined and presented in this study. © 2013 Elsevier Ltd.


Jamshidi A.,Universiti Sains Malaysia | Hamzah M.O.,Universiti Sains Malaysia | You Z.,Michigan Technological University
Construction and Building Materials | Year: 2013

Warm Mix Asphalt (WMA) technology has become increasingly popular in pavement construction because of its environmental benefits and its ability to improve the engineering properties of asphalt binders and mixtures. This state-of-the-art article focuses on various aspects of the WMA technology incorporating Sasobit® which includes the rheological characteristics of asphalt binders containing Sasobit®. The findings from laboratory tests and field performance of Sasobit®-modified WMA are also presented. This paper also reviews the life-cycle assessment, energy savings potential and greenhouse gas (GHG) emission reduction potential of WMA containing Sasobit®. The review concludes with a proposal for incorporating aspects related to environmental and energy-efficient asphalt mixes in Superpave™ mix design method. © 2012 Elsevier Ltd. All rights reserved.


Algoufi Y.T.,Universiti Sains Malaysia | Algoufi Y.T.,King Abdulaziz University | Hameed B.H.,Universiti Sains Malaysia
Fuel Processing Technology | Year: 2014

Biodiesel industry is facing a challenging problem in managing biodiesel by-product, glycerol. Utilization of by-product glycerol is crucial for sustainability of biodiesel industry. Conversion of glycerol to value-added chemicals increases the profitability of biodiesel manufacturing. Glycerol carbonate, a versatile compound derived from glycerol via transesterification of glycerol with dimethyl carbonate (DMC) was synthesized over K-zeolite derived from coal fly ash by hydrothermal treatment. The effect of different reaction parameters such as the molar ratio of DMC to glycerol, catalyst loading, reaction temperature and reaction time on the transesterification reaction was investigated. The obtained data showed that at DMC-glycerol molar ratio of 3:1, catalyst loading of 4 wt.% and reaction temperature of 75 °C, the glycerol conversion and glycerol carbonate yield from the process was 100 % and 96%, respectively. The obtained GC can be used in different energy related applications such as bio-based fuel additive and green electrolyte solvent in lithium batteries. © 2014 Elsevier B.V.


Shaik M.M.,Universiti Sains Malaysia | Gan S.H.,Universiti Sains Malaysia | Kamal M.A.,King Abdulaziz University
CNS and Neurological Disorders - Drug Targets | Year: 2014

Cognitive decline is a debilitating feature of Alzheimer's disease (AD). The causes leading to such impairment are still poorly understood and effective treatments for AD are still unavailable. Type 2 diabetes mellitus (T2DM) has been identified as a risk factor for AD due to desensitisation of insulin receptors in the brain. Recent studies have suggested that epigenetic mechanisms may also play a pivotal role in the pathogenesis of both AD and T2DM. This article describes the correlation between AD and T2DM and provides the insights to the epigenetics of AD. Currently, more research is needed to clarify the exact role of epigenetic regulation in the course and development of AD and also in relation to insulin. Research conducted especially in the earlier stages of the disease could provide more insight into its underlying pathophysiology to help in early diagnosis and the development of more effective treatment strategies. © 2014 Bentham Science Publishers.


Mardiana-Idayu A.,University of Nottingham | Mardiana-Idayu A.,Universiti Sains Malaysia | Riffat S.B.,University of Nottingham
Renewable and Sustainable Energy Reviews | Year: 2012

Recently, there is growing demand for energy saving technologies in buildings due to global warming and environmental impact issue. As a result to this, energy-efficient technologies are becoming more popular amongst researchers and designers. In this regards, to fulfil energy conservation demands, researchers have focused on the development of advance heat or energy recovery with energy-efficient ventilation system. The aim of this paper is to review heat or energy recovery technologies for building applications. The reviews were discussed according to the concept and classification of heat or energy recovery based on types and flow arrangement. The developments of these technologies in integrated energy-efficient system such as mechanical and passive ventilation, air conditioning, dehumidification and photovoltaic panel have also been presented. © 2011 Elsevier Ltd. All rights reserved.


Al Azzam K.M.,Universiti Sains Malaysia | Saad B.,Universiti Sains Malaysia | Aboul-Enein H.Y.,National Research Center of Egypt
Electrophoresis | Year: 2010

Binding constants for the enantiomers of modafinil with the negatively charged chiral selector sulfated-β-CD (S-β-CD) using CE technique is presented. The calculations of the binding constants employing three different linearization plots (double reciprocal, X-reciprocal and Y-reciprocal) were performed from the electrophoretic mobility values of modafinil enantiomers at different concentrations of S-β-CD in the BGE. The highest inclusion affinity of the modafinil enantiomers were observed for the S-enantiomer-S- β-CD complex, in agreement with the computational calculations performed previously. Binding constants for each enantiomer-S-β-CD complex at different temperatures, as well as thermodynamic parameters for binding, were calculated. Host-guest binding constants using the double reciprocal fit showed better linearity (r2>0.99) at all temperatures studied (15-30°C) and compared with the other two fit methods. The linear van't Hoff (15-30°C) plot obtained indicated that the thermodynamic parameters of complexation were temperature dependent for the enantiomers. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.


Mardiana A.,Universiti Sains Malaysia | Riffat S.B.,University of Nottingham
Renewable and Sustainable Energy Reviews | Year: 2013

Owing to global energy crisis, various technical strategies are adopted for energy conservation in buildings through energy-efficient technologies. One of the significant ways for this purpose is by installation or usage of heat or energy recovery device which is known as one of main energy-efficient systems that will decrease the power demands of building heating, cooling, air conditioning and ventilation loads. In order to have an insight into existing knowledge leading to understanding of previous works and researches carried out concerning the area, this paper presents and discusses physical and performance parameters of heat recovery unit and the significances of these parameters on operation and efficiency of the system. In addition, areas that have not received much research attention and that warrant future analysis of this technology are also highlighted. © 2013 Elsevier Ltd.


Yap K.S.,University of Tenaga Nasional | Lim C.P.,Universiti Sains Malaysia | Au M.T.,University of Tenaga Nasional
IEEE Transactions on Neural Networks | Year: 2011

Generalized adaptive resonance theory (GART) is a neural network model that is capable of online learning and is effective in tackling pattern classification tasks. In this paper, we propose an improved GART model (IGART), and demonstrate its applicability to power systems. IGART enhances the dynamics of GART in several aspects, which include the use of the Laplacian likelihood function, a new vigilance function, a new match-tracking mechanism, an ordering algorithm for determining the sequence of training data, and a rule extraction capability to elicit if-then rules from the network. To assess the effectiveness of IGART and to compare its performances with those from other methods, three datasets that are related to power systems are employed. The experimental results demonstrate the usefulness of IGART with the rule extraction capability in undertaking classification problems in power systems engineering. © 2006 IEEE.


Nauheimer L.,Ludwig Maximilians University of Munich | Boyce P.C.,Universiti Sains Malaysia | Renner S.S.,Ludwig Maximilians University of Munich
Molecular Phylogenetics and Evolution | Year: 2012

Alocasia comprises over 113 species of rainforest understorey plants in Southeast Asia, the Malesian region, and Australia. Several species, including giant taro, Alocasia macrorrhizos, and Chinese taro, Alocasia cucullata, are important food plants or ornamentals. We investigated the biogeography of this genus using plastid and nuclear DNA sequences (5200 nucleotides) from 78 accessions representing 71 species, plus 25 species representing 16 genera of the Pistia clade to which Alocasia belongs. Divergence times were inferred under strict and relaxed clock models, and ancestral areas with Bayesian and maximum likelihood approaches. Alocasia is monophyletic and sister to Colocasia gigantea from the SE Asian mainland, whereas the type species of Colocasia groups with Steudnera and Remusatia, requiring taxonomic realignments. Nuclear and plastid trees show topological conflict, with the nuclear tree reflecting morphological similarities, the plastid tree species' geographic proximity, suggesting chloroplast capture. The ancestor of Alocasia diverged from its mainland sister group c. 24 million years ago, and Borneo then played a central role in the expansion of Alocasia: 11-13 of 18-19 inferred dispersal events originated on Borneo. The Philippines were reached from Borneo 4-5. times in the Late Miocene and Early Pliocene, and the Asian mainland 6-7. times in the Pliocene. Domesticated giant taro originated on the Philippines, Chinese taro on the Asian mainland. © 2011 Elsevier Inc.


Mehat N.M.,Kolej Kemahiran Tinggi MARA | Kamaruddin S.,Universiti Sains Malaysia
Materials and Manufacturing Processes | Year: 2011

The growing amount of plastic parts produced nowadays makes the search for alternatives in recycling and the further use of these nonbiodegradable materials imperative. The degradation of the mechanical properties of recycled plastic products poses the primary limitation for the usage of recycled plastic. One of the foremost causes of mechanical property degradation is variation in processing parameters. An appropriate optimization method that effectively controls all influential processing parameters during manufacturing is therefore critical. This study investigates the effects of injection molding parameters on the mechanical properties of recycled plastic parts. The preliminary experiment is conducted by using Moldflow Plastic Insight (MPI) integrated with the L18 Taguchi orthogonal array (OA). The significant processing parameters obtained from the preliminary experiment were used to conduct the principal experiment. By adopting L9 Taguchi OA, the parts made from recycled plastic were produced by injection molding. ANOVA confirms that the most significant factor for flexural modulus of a recycled toolbox tray is injection time (∼40.49% percentage contribution). For stress at yield, the most significant factor is melt temperature with percentage contribution of about 43.34%. Copyright © Taylor & Francis Group, LLC.


Rahman Z.A.,Universiti Sains Malaysia
Journal of oral science | Year: 2010

The aim of the present study was to assess the levels of salivary cortisol, tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) before, during and after acute exercise. Acute exercise was induced using a standard treadmill test with Bruce protocol in ten physically active male participants. Unstimulated saliva was collected before, during and after exercise. The levels of salivary cortisol and TNF-alpha were assessed by enzyme immunoassays. Salivary NO was determined by the Griess reagent. The results showed that both salivary cortisol and TNF-alpha increased and peaked at 14 min during exercise and then decreased. The levels of NO were increased up to 1 h after exercise and subsequently lowered after 24 h. The results of the present study suggest that acute exercise may induce high levels of salivary cortisol, TNF-alpha and NO.


Rahman I.A.,Universiti Sains Malaysia | Padavettan V.,Intel Corporation
Journal of Nanomaterials | Year: 2012

Application of silica nanoparticles as fillers in the preparation of nanocomposite of polymers has drawn much attention, due to the increased demand for new materials with improved thermal, mechanical, physical, and chemical properties. Recent developments in the synthesis of monodispersed, narrow-size distribution of nanoparticles by sol-gel method provide significant boost to development of silica-polymer nanocomposites. This paper is written by emphasizing on the synthesis of silica nanoparticles, characterization on size-dependent properties, and surface modification for the preparation of homogeneous nanocomposites, generally by sol-gel technique. The effect of nanosilica on the properties of various types of silica-polymer composites is also summarized. © Copyright 2012 Ismail Ab Rahman and Vejayakumaran Padavettan.


Badday A.S.,Universiti Sains Malaysia | Abdullah A.Z.,Universiti Sains Malaysia | Lee K.T.,Universiti Sains Malaysia | Khayoon M.S.,Universiti Sains Malaysia | Khayoon M.S.,University of Technology, Iraq
Renewable and Sustainable Energy Reviews | Year: 2012

Biodiesel is a good alternative fuel to petroleum diesel. It is produced through transesterification reaction between vegetable oil or animal fats and alcohol. The process faces various problems related to the immiscible nature of the reactants causing poor mass transfer rate. This drawback is responsible for long reaction time and low reaction rate leading to an energy intensive process. Process intensification through the use of active catalyst, pressure reactor, high temperature, high stirring rate or even non-conventional approaches such as supercritical method and Biox process often subjects to drawbacks with respect to energy consumption, product quality and reactants cost. This paper highlights recent development in the production of biodiesel under ultrasonic irradiation conditions. It handles the drawback of poor immiscibility between reactants as ultrasonic energy can emulsify the reactants to reduce the catalyst requirement, reaction time and reaction temperature. Ultrasonic energy also neglects the limitations in the use certain feed stocks. Fundamental aspects of the ultrasonic-assisted process using homogeneous and heterogeneous catalysts are reviewed. Recent achievement and future development in this technology in a batch and continuous process are also highlighted. © 2012 Elsevier Ltd. All rights reserved.


Ng R.S.,Penang Hospital | Chong C.P.,Universiti Sains Malaysia
Australasian Medical Journal | Year: 2012

Surgical site infections are the most common nosocomial infection among surgical patients. Patients who experience surgical site infections are associated with prolonged hospital stay, rehospitalisation, increased morbidity and mortality, and costs. Consequently, surgical antimicrobial prophylaxis (SAP), which is a very brief course of antibiotic given just before the surgery, has been introduced to prevent the occurrence of surgical site infections. The efficacy of SAP depends on several factors, including selection of appropriate antibiotic, timing of administration, dosage, duration of prophylaxis and route of administration. In many institutions around the globe, evidence-based guidelines have been developed to advance the proper use of SAP. This paper aims to review the studies on surgeons' adherence to SAP guidelines and factors influencing their adherence. A wide variation of overall compliance towards SAP guidelines was noted, ranging from 0% to 71.9%. The misuses of prophylactic antibiotics are commonly seen, particularly inappropriate choice and prolonged duration of administration. Lack of awareness of the available SAP guidelines, influence of initial training, personal preference and influence from colleagues were among the factors which hindered the surgeons' adherence to SAP guidelines. Immediate actions are needed to improve the adherence rate as inappropriate use of SAP can lead to the emergence of a strain of resistant bacteria resulting in a number of costs to the healthcare system. Corrective measures to improve SAP adherence include development of guidelines, education and effective dissemination of guidelines to targeted surgeons and routine audit of antibiotic utilisation by a dedicated infection control team.


Vicknasingam B.,Universiti Sains Malaysia | Mazlan M.,Substance Abuse Research Center | Schottenfeld R.S.,Yale University | Chawarski M.C.,Yale University
Drug and Alcohol Dependence | Year: 2010

Background: Buprenorphine maintenance is efficacious for treating opioid dependence, but problems with diversion and misuse of buprenorphine (BUP) may limit its acceptability and dissemination. The buprenorphine/naloxone combination tablet (BNX) was developed to reduce potential problems with diversion and abuse. This paper provides data regarding the characteristics of BUP injection drug users in Malaysia and preliminary data regarding the impact of withdrawing BUP and introducing BNX. BUP was introduced in 2002 and subsequently withdrawn from the Malaysian market in 2006. BNX was introduced in 2007. Methods: A two wave survey of BUP IDUs was conducted shortly prior to BUP withdrawal from the Malaysian market (n=276) and six months after BNX was introduced (n=204). Six focus groups with BUP and/or BNX IDUs were also conducted shortly before the second wave. Results: In addition to current BUP or BNX IDU, 96% of first wave participants and 97% second wave participants reported lifetime heroin IDU preceding the onset of their BUP/BNX IDU. Additionally, 58% of first and 64% of second wave survey participants reported current heroin IDU. Benzodiazepine abuse, often injected with BUP, was reported in both the surveys. Focus group participants reported that BNX was not as desirable as BUP, nonetheless, the results of the second wave survey suggest a continuing widespread BNX IDU, at least in Kuala Lumpur. Conclusions: In Malaysia, BUP and BNX IDU occur among heroin IDUs. The introduction of BNX and withdrawal of BUP may have helped to reduce, but did not eliminate the problems with diversion and abuse. © 2010 Elsevier Ireland Ltd.


Chen C.K.,Universiti Sains Malaysia
Journal of physiological anthropology | Year: 2012

ABSTRACT: The use of herbs as ergogenic aids in exercise and sport is not novel. Ginseng, caffeine, ma huang (also called 'Chinese ephedra'), ephedrine and a combination of both caffeine and ephedrine are the most popular herbs used in exercise and sports. It is believed that these herbs have an ergogenic effect and thus help to improve physical performance. Numerous studies have been conducted to investigate the effects of these herbs on exercise performance. Recently, researchers have also investigated the effects of Eurycoma longifolia Jack on endurance cycling and running performance. These investigators have reported no significant improvement in either cycling or running endurance after supplementation with this herb. As the number of studies in this area is still small, more studies should be conducted to evaluate and substantiate the effects of this herb on sports and exercise performance. For instance, future research on any herbs should take the following factors into consideration: dosage, supplementation period and a larger sample size.


Recently there has been a remarkable surge of interest about natural products and their applications in the cosmetic industry. Topical delivery of antioxidants from natural sources is one of the approaches used to reverse signs of skin aging. The aim of this research was to develop a nanoemulsion cream for topical delivery of 30% ethanolic extract derived from local Phyllanthus urinaria (P. urinaria) for skin antiaging. Palm kernel oil esters (PKOEs)-based nanoemulsions were loaded with P. urinaria extract using a spontaneous method and characterized with respect to particle size, zeta potential, and rheological properties. The release profile of the extract was evaluated using in vitro Franz diffusion cells from an artificial membrane and the antioxidant activity of the extract released was evaluated using the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) method. Formulation F12 consisted of wt/wt, 0.05% P. urinaria extract, 1% cetyl alcohol, 0.5% glyceryl monostearate, 12% PKOEs, and 27% Tween 80/Span 80 (9/1) with a hydrophilic lipophilic balance of 13.9, and a 59.5% phosphate buffer system at pH 7.4. Formulation F36 was comprised of 0.05% P. urinaria extract, 1% cetyl alcohol, 1% glyceryl monostearate, 14% PKOEs, 28% Tween 80/Span 80 (9/1) with a hydrophilic lipophilic balance of 13.9, and 56% phosphate buffer system at pH 7.4 with shear thinning and thixotropy. The droplet size of F12 and F36 was 30.74 nm and 35.71 nm, respectively, and their nanosizes were confirmed by transmission electron microscopy images. Thereafter, 51.30% and 51.02% of the loaded extract was released from F12 and F36 through an artificial cellulose membrane, scavenging 29.89% and 30.05% of DPPH radical activity, respectively. The P. urinaria extract was successfully incorporated into a PKOEs-based nanoemulsion delivery system. In vitro release of the extract from the formulations showed DPPH radical scavenging activity. These formulations can neutralize reactive oxygen species and counteract oxidative injury induced by ultraviolet radiation and thereby ameliorate skin aging.


Radiotherapy plays an essential primary role in cancer patients. Regardless of its significant advances in treatment options, tumor recurrence and radio-resistance in cancer cells still occur in a high percentage of patients. Furthermore, the over expression of miRNAs accompanies the development of radio-resistant cancer cells. Consequently, miRNAs might serve as therapeutic targets for the treatment of radio-resistance in cancer cells. The findings of the current research also signify that the use of a natural anti-miRNA substance could inhibit specific miRNAs, and, concurrently, these natural remedies could exhibit radioprotective activity against the healthy cells during radiotherapy. Therefore, in this review, we have reported the association of miRNAs with radio-resistance and the potential uses of natural remedies as green gene therapeutic approaches, as well as radioprotectors against the adverse effects of irradiation on healthy cells during radiotherapy.


Mey S.C.,Universiti Sains Malaysia
International Journal of Special Education | Year: 2011

This study attempts to identify the drivers and inhibitors of employment for people with disabilities in Malaysia. It explores the skills and psychological traits needed by people with disabilities in order to get jobs and the barriers to their employment. Data include interviews detailing the viewpoints of 24 teachers with visual impairments. These teachers are registered and classified as either legally blind or partially sighted by the Malaysian Social Welfare Department. The majority of them are male, Malay, between 30-40 years old and have diploma qualification from Teachers Training College. The interviews were transcribed verbatim. Keywords or phrases were extracted, clustered, and interpreted into themes. Analyzed data were confirmed with the participants to ensure trustworthiness and reliability. The findings provide interesting insights into the specific employment issues faced by people with visual impairments and also shed lights on the issues encountered by people with other types of disability. It also discusses measures that can be taken to improve the employment rate of people with disabilities in the country. A discussion of the research findings is also provided.


Heng M.H.,Universiti Sains Malaysia
Genetics and molecular research : GMR | Year: 2012

Fusarium species section Liseola namely F. fujikuroi, F. proliferatum, F. andiyazi, F. verticillioides, and F. sacchari are well-known plant pathogens on rice, sugarcane and maize. In the present study, restriction analysis of the intergenic spacer regions (IGS) was used to characterize the five Fusarium species isolated from rice, sugarcane and maize collected from various locations in Peninsular Malaysia. From the analysis, and based on restriction patterns generated by the six restriction enzymes, Bsu151, BsuRI, EcoRI, Hin6I, HinfI, and MspI, 53 haplotypes were recorded among 74 isolates. HinfI showed the most variable restriction patterns (with 11 patterns), while EcoRI showed only three patterns. Although a high level of variation was observed, it was possible to characterize closely related species and isolates from different species. UPGMA cluster analysis showed that the isolates of Fusarium from the same species were grouped together regardless of the hosts. We conclude that restriction analysis of the IGS regions can be used to characterize Fusarium species section Liseola and to discriminate closely related species as well as to clarify their taxonomic position.


Emami A.,Universiti Sains Malaysia
Archives of dermatological research | Year: 2012

Keloid is a complex condition with environmental and genetic risk-contributing factors. Two candidate genes, TGFβ1 and SMAD4, located in the same signaling pathway are highly expressed in the keloid fibroblast cells. In a case-control design, TGFβ1 haplotypes showed association with the risk of keloid in the present study. The CC haplotype, composed of both c.29C>T and -509T>C variants, was observed more frequently among cases (Corrected p = 0.037, OR = 2.07, 95 % CI = 0.87-4.93), showing a 4.5-fold increased risk for keloid. The AG genotype of the SMAD4 c.5131A>G variant showed a trend of significance (p = 0.0573, OR = 1.75, 95 % CI = 0.99-3.13). Taken together, either of these variants is most probably causative at the expression level or is in linkage disequilibrium with other causative variants in a complex pattern together with the environmental factors that contribute to the condition. To the best of our knowledge, there is only one documented report on a relationship between TGFβ1 and keloid with no association within the Caucasian population, while there have not been any reports for SMAD4. Therefore, the present study is likely the first research showing a significant association between TGFβ1 variants and keloids in the Malay population.


Khayoon M.S.,Universiti Sains Malaysia | Khayoon M.S.,University of Technology, Iraq | Hameed B.H.,Universiti Sains Malaysia
Bioresource Technology | Year: 2011

Oxygenated fuel additives can be produced by acetylation of glycerol. A 91% glycerol conversion with a selectivity of 38%, 28% and 34% for mono-, di- and triacetyl glyceride, respectively, was achieved at 120 °C and 3. h of reaction time in the presence of a catalyst derived from activated carbon (AC) treated with sulfuric acid at 85 °C for 4. h to introduce acidic functionalities to its surface. The unique catalytic activity of the catalyst, AC-SA5, was attributed to the presence of sulfur containing functional groups on the AC surface, which enhanced the surface interaction between the glycerol molecule and acyl group of the acetic acid. The catalyst was reused in up to four consecutive batch runs and no significant decline of its initial activity was observed. The conversion and selectivity variation during the acetylation is attributed to the reaction time, reaction temperature, catalyst loading and glycerol to acetic acid molar ratio. © 2011 Elsevier Ltd.


Norsa'adah B.,Universiti Sains Malaysia
Asian Pacific journal of cancer prevention : APJCP | Year: 2013

The incidence of hepatocellular carcinoma (HCC) is relatively high in Southeast Asia. Globally, HCC has a high fatality rate and short survival. The objectives of this retrospective cohort study were to review the epidemiology and survival of HCC patients at a tertiary centre in north-east of Peninsular Malaysia. Subjects were adult HCC patients diagnosed by histopathology or radio-imaging. Secondary liver carcinoma was excluded. Kaplan Meier and multiple Cox proportional hazard survival analyses were used. Only 210 HCC cases from years 1987-2008, were included in the final analysis. The number of cases was increasing annually. The mean age was 55.0 (SD 13.9) years with male:female ratio of 3.7:1. Approximately 57.6% had positive hepatitis B virus, 2.4% hepatitis C virus, 20% liver cirrhosis and 8.1% chronic liver disease. Only 2.9% had family history and 9.0% had frequently consumed alcohol. Most patients presented with abdominal pain or discomfort and had hepatomegaly, 47.9% had an elevated α-fetoprotein level of 800 IU/ml or more, 51.9% had multiple tumors and 44.8% involved multiple liver lobes. Approximately 63.3% were in stage 3 and 23.4% in stage 4, and 82.9% did not receive any treatment. The overall median survival time was 1.9 months (95% confidence interval (CI): 1.5, 2.3). The 1-month, 6-month, 1-year and 2-year survival rates were 71.8%, 23.3%, 13.0% and 7.3% respectively. Significant prognostic factors were Malay ethnicity [Adjusted hazard ratio (AHR) 1.6; 95%CI: 1.0, 2.5; p=0.030], no chemotherapy [AHR 1.7; 95%CI: 1.1, 2.5; p=0.017] and Child-Pugh class C [AHR 2.6; 95%CI: 1.4, 4.9; p=0.002]. HCC in our study affected a wide age range, mostly male, in advanced stage of disease, with no treatment and very low survival rates. Primary prevention should be advocated in view of late presentation and difficulty of treatment. Vaccination of hepatitis virus and avoidance of liver toxins are to be encouraged.


Moniruzzaman M.,Universiti Sains Malaysia
African journal of traditional, complementary, and alternative medicines : AJTCAM / African Networks on Ethnomedicines | Year: 2012

Free radicals and reactive oxygen species (ROS) have been implicated in contributing to the processes of aging and disease. In an effort to combat free radical activity, scientists are studying the effects of increasing individuals' antioxidant levels through diet and dietary supplements. Honey appears to act as an antioxidant in more ways than one. In the body, honey can mop up free radicals and contribute to better health. Various antioxidant activity methods have been used to measure and compare the antioxidant activity of honey. In recent years, DPPH (Diphenyl-1-picrylhydrazyl), FRAP (Ferric Reducing Antioxidant Power), ORAC (The Oxygen Radical Absorbance Capacity), ABTS [2, 2-azinobis (3ehtylbenzothiazoline-6-sulfonic acid) diamonium salt], TEAC [6-hydroxy-2, 5, 7, 8-tetramethylchroman-2-carboxylic acid (Trolox)-equivalent antioxidant capacity] assays have been used to evaluate antioxidant activity of honey. The antioxidant activity of honey is also measured by ascorbic acid content and different enzyme assays like Catalase (CAT), Glutathione Peroxidase (GPO), Superoxide Dismutase (SOD). Among the different methods available, methods that have been validated, standardized and widely reported are recommended.


Abu Backer F.M.,Universiti Sains Malaysia
Infectious diseases in obstetrics and gynecology | Year: 2011

We studied the clinicopathological parameters of adenocarcinoma arising from endocervix (ECA) and from endometrium (EMA) based on the expression of P16ink4a, P21waf1, and p27Kip1 proteins. Immunohistochemistry was done on sections of confirmed ECA and EMA from hysterectomy specimens which have had no prior chemotherapy/radiotherapy. There were 40 ECAs and 92 EMAs. The mean age of ECA was 49.82 (SD 10.29); the youngest was 30 years old and the oldest 75 years old. The mean age of EMA was 54.45 (SD 10.92); the youngest was 30 years old and the oldest was 82 years old. For ECA, the size of the tumour is significantly associated with age and with depth of infiltration. FIGO stage is associated with histological grade. p21WAF1 expression is significantly associated with infiltration of the corpus and lymph node metastasis. p27Kip1 expression is significantly associated with lymph node invasion. The presence of lymph node metastasis is strongly associated when p16INK4a and p27Kip1 expressions are analyzed in combination. For EMA, p16INK4a expression is associated with histologic grade. Our study shows that we could use these cell cycle markers as predictors for more aggressive subsets of adenocarcinoma of the cervix and endometrium.


There is considerable evidence that emotional intelligence, previous academic achievement (i.e. cumulative grade point average (GPA)) and personality are associated with success in various occupational settings. This study evaluated the relationships of these variables with psychological health of first year medical students during stressful periods. A 1-year prospective study was done with students accepted into the School of Medical Sciences, Universiti Sains Malaysia. Information on emotional intelligence, GPA and personality traits were obtained prior to admission. The validated Universiti Sains Malaysia Emotional Quotient Inventory and Universiti Sains Malaysia Personality Inventory were used to measure emotional intelligence and personality traits, respectively. Stress, anxiety and depression were measured by the 21-item Depression Anxiety Stress Scale during the end-of-course (time 1) and final (time 2) examinations. At the less stressful period (time 1), stress level was associated with agreeableness and the final GPA, anxiety level was associated with emotional control and emotional conscientiousness and depression level was associated with the final GPA and extraversion. At the more stressful period (time 2), neuroticism associated with stress level, anxiety level was associated with neuroticism and emotional expression, and depression level was associated with neuroticism. This study found that neuroticism was the strongest associated factor of psychological health of medical students during their most stressful testing period. Various personality traits, emotional intelligence and previous academic performance were associated factors of psychological health during a less stressful period. These data suggest that early identification of medical students who are vulnerable to the stressful environment of medical schools might help them maintain psychological well-being during medical training.


Shafie A.A.,Universiti Sains Malaysia
Quality of life research : an international journal of quality of life aspects of treatment, care and rehabilitation | Year: 2011

The objective of this study was to assess the construct validity of the EQ-5D instrument among the Malaysian population. This was a cross-sectional study conducted among Malaysian adults in three northern states of Malaysia. A pre-developed questionnaire consisting of both the EQ-5D and SF-12 items was used for data collection. Concurrent, convergent, and known group validity of EQ-5D were assessed against SF-12 and several known relationships with participants' demographic and illness characteristics. A total of 596 Malaysians participated in the study. The mean EQ-5D score was 0.93 (SD = 0.13), while the mean physical component score (PCS-12) and mental component score (MCS-12) scores were 48.9 (SD = 7.4) and 49.1 (SD = 8.0), respectively. Participants with a current medical problem had lower PCS-12 and MCS-12 scores and reported more problems with all of the EQ-5D dimensions; they also had lower EQ-5D and EQ-VAS scores (P < 0.05). Convergent validity was supported by a moderately positive correlation between EQ-5D and EQ-VAS with MCS-12 and PCS-12 scores; moreover, the stronger effect sizes between PCS-12 and the physical dimensions of EQ-5D as well as between MCS-12 with anxiety/depression scores further supported the convergent validity of EQ-5D. Responses to the EQ-5D dimensions only supported two of the four known group validity hypotheses of higher quality of life among individuals who are better educated and no medical problem. No association was found between income and gender with EQ-5D score. This study has demonstrated acceptable construct validity of the EQ-5D among the Malaysian population.


Anabas testudineus (Anabantidae) is an important food fish in Southeast Asia. We analyzed the mitochondrial DNA control region sequence data to evaluate the genetic variability and population structure of this species. Sixty specimens were collected from four populations in Sumatra and two populations in Peninsular Malaysia. We found a very low level of genetic variability, with five of the six populations exhibiting total absence of genetic variation. Based on analysis of molecular variance, 84.72% of the total variation was among populations and 15.28% within populations. A geographical division based on FST values indicated highly significant genetic differentiation among populations from the four drainage systems: Aceh, Sumatra Utara, Pulau Pinang, and Terengganu (FST ranging from 0.633 to 1.000). No phylogeographic relationships among populations were detected, despite the generation of four distinct clades in a neighbor-joining phylogenetic tree.


Hermida L.,Universiti Sains Malaysia | Hermida L.,Lampung University | Abdullah A.Z.,Universiti Sains Malaysia | Mohamed A.R.,Universiti Sains Malaysia
Renewable and Sustainable Energy Reviews | Year: 2015

Deoxygenation process of fatty acid as a renewable resource to produce diesel-like hydrocarbons is one of the alternatives to address drastic shortage of crude oil-based fuels in the near future. Catalytic deoxygenation process of fatty acid is getting attention from both academia and industry. Researchers have tried different techniques in the fatty acid deoxygenation to enhance the production of diesel-like hydrocarbons. This review paper elucidates the influence of tmain operating conditions towards achieving optimum yield and selectivity of desired products. The reaction pathways, the reaction kinetics as well as recent progress in deoxygenation of fatty acid for production of diesel-like hydrocarbons are also reviewed. © 2014 Elsevier Ltd. All rights reserved.


Zailani S.,Universiti Sains Malaysia | Jeyaraman K.,Universiti Sains Malaysia | Vengadasan G.,Universiti Sains Malaysia | Premkumar R.,AIMST University
International Journal of Production Economics | Year: 2012

As a developing country, Malaysia has moved from an agriculture-based economy to an industrialized economy in which manufacturing is considered to be the highest contributor towards environmental concerns. These concerns push firms into seriously considering the environmental impact while doing their business. The implementation of sustainable supply chain management (SSCM) is a key enabler that could push organizations to focus on alleviating environmental issues, and providing economic and social benefits. This study investigates the extent of implementation of sustainable supply chain management practices (environmental purchasing and sustainable packaging). The study also examines the outcomes of these practices on sustainable supply chain performance. A survey via mail was carried out among 400 manufacturing firms in Malaysia. Factor analysis of the survey data resulted in four categories of outcomes (environmental, economic, social and operational). The study found that environmental purchasing has a positive effect on three categories of outcomes (economic, social and operational), whereas sustainable packaging has a positive effect on environmental, economic and social outcomes. The results have empirically proven that SSCM practices have a positive effect on sustainable supply chain performance, particularly from the economic and social perspective. Thus, firms need to collaborate in advocating sustainable supply chain management (SSCM) practices as a route for firm's commercial success rather than as a moral obligation. © 2012 Elsevier B.V. All rights reserved.


Che Yaakob C.A.,Universiti Sains Malaysia
Cochrane database of systematic reviews (Online) | Year: 2010

BACKGROUND: Thromboembolic complications are much higher in pregnancy due to procoagulant changes. Heparin does not cross the placenta and the use of unfractionated heparin (UFH) is the current established practice in prophylaxis and treatment for thromboembolism in pregnancy. OBJECTIVES: To compare the effectiveness of anticoagulant therapies for the treatment of deep vein thrombosis in pregnancy. The anticoagulant drugs included are UFH, low molecular weight heparin (LMWH) and warfarin. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (March 2010) and reference lists of retrieved studies. SELECTION CRITERIA: Randomised controlled trials comparing any combination of warfarin, UFH, LMWH and placebo in pregnant women. DATA COLLECTION AND ANALYSIS: We used methods described in the Cochrane Handbooks for Systemic Reviews of Interventions for assessing the eligibility of studies identified by the search strategy. A minimum of two review authors independently assessed each study. MAIN RESULTS: We did not identify any eligible studies for inclusion in the review.We identified three potential studies; after assessing eligibility, we excluded all three as they did not meet the prespecified inclusion criteria. One study compared LMWH and UFH in pregnant women with previous thromboembolic events and, for most of these women, anticoagulants were used as thromboprophylaxis. There were only three women who had a thromboembolic event during the current pregnancy and it was unclear whether the anticoagulant was used as therapy or prophylaxis. We excluded one study because it included only women undergoing caesarean birth. The third study was not a randomised trial. AUTHORS' CONCLUSIONS: There is no evidence from randomised controlled trials on the effectiveness of anticoagulation for deep vein thrombosis in pregnancy. Further studies are required.


As a topical delivery system, a nanoscaled emulsion is considered a good carrier of several active ingredients that convey several side effects upon oral administration, such as nonsteroidal anti-inflammatory drugs (NSAIDs). We investigated the in vitro permeation properties and the in vivo pharmacodynamic activities of different nanoscaled emulsions containing ibuprofen, an NSAID, as an active ingredient and newly synthesized palm olein esters (POEs) as the oil phase. A ratio of 25:37:38 of oil phase:aqueous phase:surfactant was used, and different additives were used for the production of a range of nanoscaled emulsions. Carbopol® 940 dispersion neutralized by triethanolamine was employed as a rheology modifier. In some circumstances, menthol and limonene were employed at different concentrations as permeation promoters. All formulae were assessed in vitro using Franz diffusion cell fitted with full-thickness rat skin. This was followed by in vivo evaluation of the anti-inflammatory and analgesic activities of the promising formulae and comparison of the effects with that of the commercially available gel. Among all other formulae, formula G40 (Carbopol® 940-free formula) had a superior ability in transferring ibuprofen topically compared with the reference. Carbopol® 940 significantly decreased the amount of drug transferred from formula G41 through the skin as a result of swelling, gel formation, and reduction in drug thermodynamic activity. Nonetheless, the addition of 10% w/w of menthol and limonene successfully overcame this drawback since, relative to the reference, higher amount of ibuprofen was transferred through the skin. By contrast, these results were relatively comparable to that of formula G40. Pharmacodynamically, the G40, G45, and G47 formulae exhibited the highest anti-inflammatory and analgesic effects compared with other formulae. The ingredients and the physical properties of the nanoscaled emulsions produced by using the newly synthesized POEs succeeded to deliver ibuprofen competently.


Inhaled corticosteroids provide unique systems for local treatment of asthma or chronic obstructive pulmonary disease. However, the use of poorly soluble drugs for nebulization has been inadequate, and many patients rely on large doses to achieve optimal control of their disease. Theoretically, nanotechnology with a sustained-release formulation may provide a favorable therapeutic index. The aim of this study was to determine the feasibility of using sterically stabilized phospholipid nanomicelles of budesonide for pulmonary delivery via nebulization. PEG(5000)-DSPE polymeric micelles containing budesonide (BUD-SSMs) were prepared by the coprecipitation and reconstitution method, and the physicochemical and pharmacodynamic characteristics of BUD-SSMs were investigated. The optimal concentration of solubilized budesonide at 5 mM PEG(5000)-DSPE was 605.71 ± 6.38 μg/mL, with a single-sized peak population determined by photon correlation spectroscopy and a particle size distribution of 21.51 ± 1.5 nm. The zeta potential of BUD-SSMs was -28.43 ± 1.98 mV. The percent entrapment efficiency, percent yield, and percent drug loading of the lyophilized formulations were 100.13% ± 1.09%, 97.98% ± 1.95%, and 2.01% ± 0.02%, respectively. Budesonide was found to be amorphous by differential scanning calorimetry, and had no chemical interaction with PEGylated polymer according to Fourier transform infrared spectroscopy. Transmission electron microscopic images of BUD-SSMs revealed spherical nanoparticles. BUD-SSMs exhibited prolonged dissolution behavior compared with Pulmicort Respules (P < 0.05). Aerodynamic characteristics indicated significantly higher deposition in the lungs compared with Pulmicort Respules. The mass median aerodynamic, geometric standard deviation, percent emitted dose, and the fine particle fraction were 2.83 ± 0.08 μm, 2.33 ± 0.04 μm, 59.13% ± 0.19%, and 52.31% ± 0.25%, respectively. Intratracheal administration of BUD-SSMs 23 hours before challenge (1 mg/kg) in an asthmatic/chronic obstructive pulmonary disease rat model led to a significant reduction in inflammatory cell counts (76.94 ± 5.11) in bronchoalveolar lavage fluid compared with administration of Pulmicort Respules (25.06 ± 6.91). The BUD-SSMs system might be advantageous for asthma or chronic obstructive pulmonary disease and other inflammatory airway diseases.


Sasongko T.H.,Universiti Sains Malaysia
The Cochrane database of systematic reviews | Year: 2013

Sickle cell disease is a group of disorders characterized by deformation of erythrocytes. Renal damage is a frequent complication in sickle cell disease as a result of long-standing anemia and disturbed circulation through the renal medullary capillaries. Due to the improvement in life expectancy of people with sickle cell disease, there has been a corresponding significant increase in the incidence of renal complications. Microalbuminuria and proteinuria are noted to be a strong predictor of subsequent renal failure. There is extensive experience and evidence with angiotensin-converting enzyme (ACE) inhibitors over many years in a variety of clinical situations for patients who do not have sickle cell disease, but their effect in patients with this disease is unknown. It is common practice to administer ACE inhibitors for sickle nephropathy due to their renoprotective properties; however, little is known about their effectiveness and safety in this setting. To determine the effectiveness of ACE inhibitor administration in people with sickle cell disease for decreasing intraglomerular pressure, microalbuminuria and proteinuria and to to assess the safety of ACE inhibitors as pertains to their adverse effects. The authors searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Hameoglobinopathies Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Date of the most recent search: 05 July 2012. Randomized or quasi-randomized controlled trials of ACE inhibitors designed to reduce microalbuminuria and proteinuria in people with sickle cell disease compared to either placebo or standard treatment regimen. Three authors independently applied the inclusion criteria in order to select studies for inclusion in the review. Two authors assessed the risk of bias of studies and extracted data and the third author verified these assessments. Five studies were identified through the searches, only one met our inclusion criteria. The included study randomized 22 participants (7 males and 15 females) having proteinuria or microalbuminuria with sickle cell disease and treated the participants for six months (median length of follow-up of three months) with captopril or placebo. At six months, the study reported no significant difference in urinary albumin excretion between the captopril group and the placebo group, although the mean urinary albumin excretion in the captopril group was lower by a mean difference of -49.00 (95% confidence interval -124.10 to 26.10) compared to that of placebo. However, our analysis on the absolute change score showed significant changes between the two groups by a mean difference of -63.00 (95% confidence interval -93.78 to -32.22). At six months albumin excretion in the captopril group was noted to decrease from baseline by a mean of 45 ± 23 mg/day and the placebo group was noted to increase by 18 ± 45 mg/day. Serum creatinine and potassium levels were reported constant throughout the study. The potential for inducing hypotension should be highlighted; the study reported a decrease of 8 mmHg in systolic pressure and 5 mmHg in diastolic and mean blood pressure. There is not enough evidence to show that the administration of ACE inhibitors is associated with a reduction of microalbuminuria and proteinuria in people with sickle cell disease, although a potential for this was seen. More long-term studies involving multiple centers and larger cohorts using a randomized-controlled design are warranted, especially among the pediatric age group. Detailed reporting of each outcome measure is necessary to allow a clear cut interpretation in a systematic review. One of the difficulties encountered in this review was the lack of detailed data reported in the included study.


Foo K.Y.,Universiti Sains Malaysia
Bioresource technology | Year: 2012

Microwave heating was used in the regeneration of methylene blue-loaded activated carbons produced from fibers (PFAC), empty fruit bunches (EFBAC) and shell (PSAC) of oil palm. The dye-loaded carbons were treated in a modified conventional microwave oven operated at 2450 MHz and irradiation time of 2, 3 and 5 min. The virgin properties of the origin and regenerated activated carbons were characterized by pore structural analysis and nitrogen adsorption isotherm. The surface chemistry was examined by zeta potential measurement and determination of surface acidity/basicity, while the adsorptive property was quantified using methylene blue (MB). Microwave irradiation preserved the pore structure, original active sites and adsorption capacity of the regenerated activated carbons. The carbon yield and the monolayer adsorption capacities for MB were maintained at 68.35-82.84% and 154.65-195.22 mg/g, even after five adsorption-regeneration cycles. The findings revealed the potential of microwave heating for regeneration of spent activated carbons. Copyright © 2012 Elsevier Ltd. All rights reserved.


Erejuwa O.O.,Universiti Sains Malaysia
International journal of biological sciences | Year: 2011

Diabetes mellitus is associated with deterioration of glycemic control and progressive metabolic derangements. This study investigated the effect of honey as an adjunct to glibenclamide or metformin on glycemic control in streptozotocin-induced diabetic rats. Diabetes was induced in rats by streptozotocin. The diabetic rats were randomized into six groups and administered distilled water, honey, glibenclamide, glibenclamide and honey, metformin or metformin and honey. The animals were treated orally once daily for four weeks. The diabetic control rats showed hypoinsulinemia (0.27 ± 0.01 ng/ml), hyperglycemia (22.4 ± 1.0 mmol/L) and increased fructosamine (360.0 ± 15.6 μmol/L). Honey significantly increased insulin (0.41 ± 0.06 ng/ml), decreased hyperglycemia (12.3 ± 3.1 mmol/L) and fructosamine (304.5 ± 10.1 μmol/L). Although glibenclamide or metformin alone significantly (p < 0.05) reduced hyperglycemia, glibenclamide or metformin combined with honey produced significantly much lower blood glucose (8.8 ± 2.9 or 9.9 ± 3.3 mmol/L, respectively) compared to glibenclamide or metformin alone (13.9 ± 3.4 or 13.2 ± 2.9 mmol/L, respectively). Similarly, glibenclamide or metformin combined with honey produced significantly (p < 0.05) lower fructosamine levels (301.3 ± 19.5 or 285.8 ± 22.6 μmol/L, respectively) whereas glibenclamide or metformin alone did not decrease fructosamine (330.0 ± 29.9 or 314.6 ± 17.9 μmol/L, respectively). Besides, these drugs or their combination with honey increased insulin levels. Glibenclamide or metformin combined with honey also significantly reduced the elevated levels of creatinine, bilirubin, triglycerides, and VLDL cholesterol. These results indicate that combination of glibenclamide or metformin with honey improves glycemic control, and provides additional metabolic benefits, not achieved with either glibenclamide or metformin alone.


Boukraa L.,Universiti Sains Malaysia
Forschende Komplementärmedizin (2006) | Year: 2010

Management of the burn wound still remains a matter of debate, and an ideal dressing for burn wounds has not yet been discovered. Naturally occurring substances such as honey have been found to be useful as a wound cover for burns. Unlike most conventional local chemotherapeutics, honey does not lead to the development of antibiotic-resistant bacteria, and it may be used continuously. Among the challenging problems of using honey for medical purposes are dosage, safety, and formulation. Many approaches have been suggested to overcome such problems. With the increased availability of licensed medical products containing honey, clinical use is expected to increase and further evidence will become available. Honey seems to have the potential to clear infection as well as to be an effective prophylactic agent that may contribute to reducing the risks of cross-infection. A better understanding of the therapeutic and chemical properties of honey is needed to optimise the use of this product in the clinical management of burns. Its use in professional care centres should be limited to those with certified healing activities. The potentials and limitations of using honey as burn dressing are discussed in this review. Copyright 2010 S. Karger AG, Basel.


Nurul Syazana M.S.,Universiti Sains Malaysia
African journal of traditional, complementary, and alternative medicines : AJTCAM / African Networks on Ethnomedicines | Year: 2013

The constituents of honey's volatile compounds depend on the nectar source and differ depending on the place of origin. To date, the volatile constituents of Tualang honey have never been investigated. The objective of this study was to analyze the volatile compounds in local Malaysian Tualang honey. A continuous extraction of Tualang honey using five organic solvents was carried out starting from non-polar to polar solvents and the extracted samples were analysed using gas chromatography-mass spectrometry (GC-MS). Overall, 35 volatile compounds were detected. Hydrocarbons constitute 58.5% of the composition of Tualang honey. Other classes of chemical compounds detected included acids, aldehydes, alcohols, ketones, terpenes, furans and a miscellaneous group. Methanol yielded the highest number of extracted compounds such as acids and 5-(Hydroxymethyl) furfural (HMF). This is the first study to describe the volatile compounds in Tualang honey. The use of a simple one tube, stepwise, non-thermal liquid-liquid extraction of honey is a advantageous as it prevents sample loss. Further research to test the clinical benefits of these volatile compounds is recommended.


Ong S.Y.,Universiti Sains Malaysia
Journal of integrative bioinformatics | Year: 2010

Signal transduction through protein-protein interactions and protein modifications are the main mechanisms controlling many biological processes. Here we described the implementation of MedScan information extraction technology and Pathway Studio software (Ariadne Genomics Inc.) to create a Salmonella specific molecular interaction database. Using the database, we have constructed several signal transduction pathways in Salmonella enterica serovar Typhi which causes Typhoid Fever, a major health threat especially in developing countries. S. Typhi has several pathogenicity islands that control rapid switching between different phenotypes including adhesion and colonization, invasion, intracellular survival, proliferation, and biofilm formation in response to environmental changes. Understanding of the detailed mechanism for S. Typhi survival in host cells is necessary for development of efficient detection and treatment of this pathogen. The constructed pathways were validated using publically available gene expression microarray data for Salmonella.


Hussein N.S.,Universiti Sains Malaysia
Saudi journal of kidney diseases and transplantation : an official publication of the Saudi Center for Organ Transplantation, Saudi Arabia | Year: 2013

Urolithiasis is a common disease with increasing incidence and prevalence world-wide, probably more common in industrialized countries. The metabolic evaluation of 24-h urine collection has been considered as part of the management of urinary stone patients. The aim of this study was to evaluate the 24-h urine constituents in stone formers and its relation to demographic data in the northeast part of Peninsular Malaysia. One hundred and six patients were recruited in this study from two hospitals in the same geographical region; 96 patients fulfilled the inclusion criteria and an informed consent was obtained from all subjects. The 24-h urine was collected in sterile bottles with a preservative agent and calcium, oxalate, citrate, uric acid, magnesium and phosphate were tested using commercial kits on a Roche Hitachi 912 chemistry analyzer. The age (mean ± SD) of 96 patients was 56.45 ± 13.43 years and 82.3% of the patients were male while 17.7% were female. The 24-h urine abnormalities were hypercalciuria (14.5%), hyperoxaluria (61.4%), hypocitraturia (57.2%), hyperuricouria (19.7%), hypomagnesuria (59.3%) and hyperphosphaturia (12.5%). Hyperoxaluria (61.4%) was the most common abnormality detected during the analysis of 24-h urine constituents in contradiction to industrial countries, where hypercalciuria was the most common finding. The high frequencies of hypomagnesuria and hypocitraturia reflect the important role of magnesium and citrate in stone formation and their prophylactic role in the treatment of urinary stone disease in the given population.


Khayoon M.S.,Universiti Sains Malaysia | Khayoon M.S.,University of Technology, Iraq | Olutoye M.A.,Universiti Sains Malaysia | Hameed B.H.,Universiti Sains Malaysia
Bioresource Technology | Year: 2012

Methyl esters were synthesized from crude karanj oil (CKO) by single step esterification with methanol using sulfuric acid (H 2SO 4) and phosphoric acid (H 3PO 4) as catalysts in a homogeneous batch process. H 3PO 4 was less active than H 2SO 4 during the process as it presented very low ester yields (<20%) for the various molar ratios of fatty acid to alcohol studied. With H 2SO 4 as catalyst, the yield was as high as 89.8% at 65°C after 5h. The fatty acids profile of the oil (palmitic acid: ∼12%; stearic acid: ∼8%; oleic acid: ∼52% and linolenic acid of 17%) and the different reactivities of the acids were responsible for the observed differences in conversion to methyl esters. The findings attained with this study might contribute to the economic utilization of a non-edible feedstock. © 2012 Elsevier Ltd.


Syed-Mohamad S.M.,Universiti Sains Malaysia
The HIM journal | Year: 2010

This paper describes the method used to develop the One Stop Crisis Centre (OSCC) Portal, an open source web-based electronic patient record system (EPR) for the One Stop Crisis Center, Hospital Universiti Sains Malaysia (HUSM) in Kelantan, Malaysia. Features and functionalities of the system are presented to demonstrate the workflow. Use of the OSCC Portal improved data integration and data communication and contributed to improvements in care management. With implementation of the OSCC portal, improved coordination between disciplines and standardisation of data in HUSM were noticed. It is expected that this will in turn result in improved data confidentiality and data integrity. The collected data will also be useful for quality assessment and research. Other low-resource centers with limited computer hardware and access to open-source software could benefit from this endeavour.


Chew A.L.,Universiti Sains Malaysia | Jessica J.J.A.,AIMST University | Sasidharan S.,Universiti Sains Malaysia
Asian Pacific Journal of Tropical Biomedicine | Year: 2012

Objective: To evaluate antioxidant, antimicrobial and cytotoxic activity of different parts (root, flower, leaf and stem) of Leucas aspera (L. aspera) (Labiatae). Methods: Different parts of L. aspera were extracted with 80% (v/v) methanol. The methanol extracts were subjected to antioxidant, antimicrobial and brine shrimp lethality assay. Results: All the extracts showed moderate to potent antioxidant activity, among which the root extract demonstrated the strongest antioxidant activity with the IC50 value of 6.552 μ g/mL. Methanol extract of root possessed antioxidant activity near the range of vitamin E and thus could be a potential rich source of natural antioxidant. In case of antimicrobial screening, crude extracts of root, flower, leaf and stem showed notable antibacterial activity against tested microorganisms. The root extract showed the highest mean zone of inhibition ranging from 9.0-11.0 mm against tested microorganisms, at a concentration of 100 mg/mL. In the brine shrimp lethality bioassay, it was evident that the methanol root extract did not show significant toxicity. The LC50 value for 12 h and 24 h observation was 2.890 mg/mL and 1.417 mg/mL, respectively. Conclusions: The present finding suggests that the methanol root extract of L. aspera could be developed as pharmaceutical products.


Ahmad N.,Universiti Sains Malaysia
American Journal of Therapeutics | Year: 2016

Although Pakistan has a high burden of multidrug-resistant tuberculosis (MDR-TB), little is known about prevalence, management, and risk factors for adverse drug reactions (ADRs) in MDR-TB patients in Pakistan. To evaluate occurrence, management, and risk factors for ADRs in MDR-TB patients, and its impact on treatment outcomes, this observational cohort study was conducted at programmatic management unit for drug resistant TB of Lady Reading Hospital Peshawar, Pakistan. A total of 181 MDR-TB patients enrolled at the study site from January 1, 2012 to February 28, 2013 were included. Patients with drug resistant TB other than MDR-TB, transferred out patients and those who were still on treatment at the end of study duration (January 31, 2015) were excluded. Patients were followed until treatment outcomes were reported. ADRs were determined by laboratory data and/or clinical criteria. SPSS 16 was used for data analysis. A total of 131 patients (72.4%) experienced at least 1 ADR. Gastrointestinal disturbance was the most commonly observed adverse event (42%), followed by psychiatric disturbance (29.3%), arthralgia (24.3%), and ototoxicity (21%). Potentially life-threatening ADRs, such as nephrotoxicity (2.7%) and hypokalemia (2.8%) were relatively less prevalent. Owing to ADRs, treatment regimen was modified in 20 (11%) patients. On multivariate analysis, the only risk factor for ADRs was baseline body weight ≥ 40 kg (OR = 2.321, P-value = 0.013). ADRs neither led to permanent discontinuation of treatment nor adversely affected treatment outcomes. Adverse effects were prevalent in current cohort, but caused minimal modification of treatment regimen, and did not negatively impact treatment outcomes. Patient with baseline body weight ≥ 40 kg should be closely monitored. Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.


Noordin R.,Universiti Sains Malaysia
BMC research notes | Year: 2014

BACKGROUND: Helicobacter pylori is a human pathogen and during the process of infection, antigens from the bacterium elicit strong host humoral immune responses. In our previous report, native H. pylori UreG protein showed good reactivity with sera from H. pylori patients. This study was aimed at producing the recombinant form of the protein (rUreG) and determining its seroreactivities.METHODS: The coding sequence of H. pylori UreG was cloned and the recombinant protein expressed and purified by affinity chromatography using nickel nitrilotriacetic acid (Ni-NTA) resin. The antigenicity of rUreG to detect H. pylori specific antibodies was determined by western blot, using HRP-conjugated anti-human IgG and IgA antibodies as probes. A total of 70 sera, comprising 30 positive and 40 control serum samples, were used. The positive sera were from culture-positive H. pylori-infected patients with duodenal ulcers, gastric ulcers, or gastritis. The control sera comprised three types of samples without detectable H. pylori antibodies, i.e. healthy individuals (with no history of gastric disorders) (n = 10); patients who attended an endoscopy clinic (because of gastrointestinal complaints) but were H. pylori culture negative (n = 20); and people with other diseases (n = 10). Additionally, hyperimmune mice serum against rUreG was raised and tested with the native and recombinant UreG protein.RESULTS: The ureG gene fragment was successfully cloned and expressed in both soluble and insoluble forms. Western blots on rUreG protein showed 70% (21/30) and 60% (18/30) reactivity with patients' sera when probed with HRP-conjugated anti-human IgG and IgA antibodies, respectively; and the combination of the IgG and IgA western blots showed reactivity of 83.3% (25/30). By comparison, 97.5% and 92.5% of the control sera showed no reactivity when probed with HRP-conjugated anti-human IgG and IgA antibodies, respectively. Both the H. pylori lysate antigen and rUreG protein displayed a distinctive band at the expected molecular weight when probed with the hyperimmune mice serum.CONCLUSION: The rUreG protein was successfully cloned and expressed and showed good reactivity with H. pylori culture-positive patients' sera and no reactivity with most control sera. Thus, the diagnostic potential of this recombinant protein merits further investigation.


Pour B.M.,AIMST University | Sasidharan S.,Universiti Sains Malaysia
Asian Pacific Journal of Tropical Biomedicine | Year: 2011

Objective: To investigate the toxicity of methanol extract of various parts (Root, Stem, Leaf, Flower and Fruit) of Lantana camara (L. Camara) in Artemia salina. Methods: The methanol extracts of L. camara were tested for in vivo brine shrimp lethality assay. Results: All the tested extract exhibited very low toxicity on brine shrimp larva. The results showed that the root extract was the most toxic part of L. camara and may have potential as anticancer agent. Conclusions: Methanolic extract of L. camara is relatively safe on short-term exposure. © 2011 Asian Pacific Tropical Biomedical Magazine.


Azamathulla H.,Universiti Sains Malaysia | Ahmad Z.,Indian Institute of Technology Roorkee
Journal of Hydrology | Year: 2012

This study presents gene-expression programming (GEP), which is an extension of genetic programming (GP), as an alternative approach to predict the transverse mixing coefficient in open channel flows. Laboratory data were collected in the present study and also from the literature for the transverse mixing coefficient covering wide range of flow conditions. These data were used for the development and testing of the proposed method. A functional relation for the estimation of transverse mixing coefficient has been developed using GEP. The proposed GEP approach produced satisfactory results compared to the existing predictors for the transverse mixing coefficient. © 2012 Elsevier B.V..


Saharudin K.A.,Universiti Sains Malaysia | Sreekantan S.,Universiti Sains Malaysia | Lai C.W.,University of Malaya
Materials Science in Semiconductor Processing | Year: 2014

One-dimensional TiO2 nanotube arrays produced by the anodization of Ti foil at 60 V in an ethylene glycol bath containing ammonium fluoride and 1 wt% H2O holds a promise as a photocatalyst for degradation of methyl orange. However, as-anodized TiO2 nanotubes are amorphous in nature, imposing constraints on the potent use of this nanostructure. To address this issue, the as-anodized TiO2 nanotubes were annealed in inert (argon), reducing (nitrogen), or oxidizing (oxygen) atmosphere at 500 C for 4 h. The amorphous TiO2 nanotubes were successfully transform into anatase phase after annealing. In this study, the TiO2 nanotubes annealed in argon exhibited the highest degradation rate of methyl orange (MO) solution under ultraviolet irradiation among the samples. The degradation rate was approximately 98% after 5 h, which may be ascribed to the large amount of oxygen vacancies and defects (carbon) within the Ar-TiO2 sample that simultaneously increased the degradation rate of MO. Oxygen vacancies and defects could be favorable in capturing photoinduced e- during the photocatalytic reaction such that the recombination of e- and h + could be effectively inhibited. © 2013 Elsevier Ltd.


Ahmad Z.,Indian Institute of Technology Roorkee | Azamathulla H.,Universiti Sains Malaysia
Journal of Hydrology | Year: 2012

Free overfall at the abrupt end of a channel offers a simple method for measurement of discharge from a single measurement of depth of flow at the brink. The theoretical procedure applied to compute discharge over a weir is applied to the free overfall to obtain end-depth-discharge relationship for subcritical and super critical flows. Pressure distribution at the brink, which is assumed a quadratic parabola, is incorporated in the analysis. A closed form equation for discharge in terms of end depth for subcritical flows was proposed and validated earlier with available experimental data in place of a derived implicit complex equation. Direct solution for discharge for known end depth is provided in the graphical form for super critical flows. Verification of this solution with available experimental data revealed that comparison is not as good as it is observed in subcritical flows. The difference in computed and observed results is attributed to the greater effect of streamline curvature and estimation of pressure factor in the supercritical flows. © 2012 Elsevier B.V.


Zolkepli I.A.,Universiti Sains Malaysia | Kamarulzaman Y.,University of Malaya
Computers in Human Behavior | Year: 2015

This research is designed to empirically investigate how social media needs and innovation influence the adoption of social media amongst Internet users. The theoretical perspective of the uses and gratifications, and Rogers' five characteristics of innovation are reviewed and extended to explain the needs and motivations of the consumer. The study is conducted by testing and quantifying the relationship between the uses and gratifications of social media, while taking into consideration the mediating effect of social media technology innovation. This research applies a two-phase, multimethod strategy in the context of Malaysia. The strategy comprises the qualitative approach via focus group discussions (FGDs) with 48 respondents and the quantitative approach via online survey questionnaires with 428 respondents. Overall, the findings suggest that social media adoption is significantly driven by three types of need category - personal (consisting of enjoyment and entertainment), social (consisting of social influence and interaction) and tension release (consisting of belongingness, companionship, playfulness). In turn, these needs are motivated by the social media innovation characteristics (relative advantage, observability, compatibility) that increase the likelihood of the adoption. The research makes a significant contribution in the area of media and technology adoption, which can be used to help marketers understand the factors that motivate social media usage, particularly the UXDs in designing human-computer interaction strategies. © 2014 Elsevier Ltd. All rights reserved.


Ahmad Z.,Indian Institute of Technology Roorkee | Azamathulla H.,Universiti Sains Malaysia
Journal of Hydrology | Year: 2012

Free overfall at the end of a circular channel is simulated as sharp-crested weir with zero height to get end-depth-discharge relationship. A closed-form equation for discharge in terms of end depth for subcritical flows is proposed and verified with the experimental data. Computed discharges show excellent matching with the observed data. Direct solution for discharge for known end depth, channel bed slope, and Manning's coefficient is provided in the graphical form for supercritical flow. Verification of this solution with the available experimental data revealed that computed discharges are within ±12% of the observed discharges. © 2012 Elsevier B.V..


Hassan N.K.,Universiti Sains Malaysia | Hassan N.K.,University of Tikrit | Hashim M.R.,Universiti Sains Malaysia
Journal of Alloys and Compounds | Year: 2013

Ultra violet photodetector based on flake-like ZnO with different flakes density were electrochemically deposited on silicon Si (111) substrate were fabricated. The deposition time greatly affected the shape, density and size of the flake, thereby altering its optical properties. The structural and optical properties of the fabricated nanostructures revealed ZnO structures with single crystalline hexagonal wurtzite containing two photoluminescence spectrum peaks at a near-band-edge emission in the ultraviolet region and a broad deep-level emission around the green emission. These peaks were affected by the period of deposition. The crystallinity of materials and the defects in the crystal structure were studied through Raman spectroscopy. Current voltage results showed that the flakes density greatly affected the ultra violet detection. Our results showed that photoresponse properties of the photodetectors strongly depend on the flakes density. The sharper flakes with high density exhibited enhanced UV detection performance, high sensitivity and shortened rise times compared to lower ones. We showed that photodetectors based on sharp, highly dense ZnO nanoflakes have a faster response than ones based on larger and lower density of ZnO nanoflakes. © 2013 Elsevier B.V. All rights reserved.


Al-Betar M.A.,Universiti Sains Malaysia | Al-Betar M.A.,Al-Zaytoonah University of Jordan | Khader A.T.,Universiti Sains Malaysia | Zaman M.,Universiti Sains Malaysia
IEEE Transactions on Systems, Man and Cybernetics Part C: Applications and Reviews | Year: 2012

University course timetabling problem (UCTP) is considered to be a hard combinatorial optimization problem to assign a set of events to a set of rooms and timeslots. Although several methods have been investigated, due to the nature of UCTP, memetic computing techniques have been more effective. A key feature of memetic computing is the hybridization of a population-based global search and the local improvement. Such hybridization is expected to strike a balance between exploration and exploitation of the search space. In this paper, a memetic computing technique that is designed for UCTP, called the hybrid harmony search algorithm (HHSA), is proposed. In HHSA, the harmony search algorithm (HSA), which is a metaheuristic population-based method, has been hybridized by: 1) hill climbing, to improve local exploitation; and 2) a global-best concept of particle swarm optimization to improve convergence. The results were compared against 27 other methods using the 11 datasets of Socha et al. comprising five small, five medium, and one large datasets. The proposed method achieved the optimal solution for the small dataset with comparable results for the medium datasets. Furthermore, in the most complex and large datasets, the proposed method achieved the best results. © 1998-2012 IEEE.


Raja P.B.,Universiti Sains Malaysia | Qureshi A.K.,University of Malaya | Abdul Rahim A.,Universiti Sains Malaysia | Osman H.,Universiti Sains Malaysia | Awang K.,University of Malaya
Corrosion Science | Year: 2013

The inhibition effect of Neolamarckia cadamba crude extract (bark, leaves) and pure alkaloid (3β-isodihydrocadambine) were investigated for mild steel corrosion in 1. M HCl medium. Potentiodynamic polarization, electrochemical impedance, scanning electron microscopy, FTIR spectroscopy and molecular modelling were employed for this study. Results showed that crude extracts and 3β-isodihydrocadambine reduced the corrosion rate significantly at all concentrations. Polarization measurements indicated that these green inhibitors acted through mixed type inhibition. SEM studies evidenced the formation of a protective film over metal surface while FTIR, supported by molecular modelling proved that this shielding effect was caused by alkaloids, particularly 3β-isodihydrocadambine. © 2012 Elsevier Ltd.


How H.G.,University of Malaya | Masjuki H.H.,University of Malaya | Kalam M.A.,University of Malaya | Teoh Y.H.,University of Malaya | Teoh Y.H.,Universiti Sains Malaysia
Energy | Year: 2014

An experimental investigation on engine performance, emissions, combustion and vibration characteristics with coconut biodiesel fuels was conducted in a high-pressure common-rail diesel engine under five different load operations (0.17, 0.34, 0.52, 0.69 and 0.86MPa). The test fuels included a conventional diesel fuel and four different fuel blends of coconut biodiesel (B10, B20, B30 and B50). The results showed that biodiesel blended fuels have significant influences on the BSFC (brake specific fuel consumption) and BSEC (brake specific energy consumption) at all engine loads. In general, the use of coconut biodiesel blends resulted in a reduction of BSCO (brake specific carbon monoxide) and smoke emissions regardless of the load conditions. A large reduction of 52.4% in smoke opacity was found at engine load of 0.86MPa engine load with B50. For combustion characteristics, a slightly shorter ignition delay and longer combustion duration were found with the use of biodiesel blends under all loading operations. It was found that generally the biodiesel blends produced lower peak heat release rate than baseline diesel. The vibration results showed that the largest reduction of 13.7% in RMS (root mean square) of acceleration was obtained with B50 at engine load of 0.86MPa with respect to the baseline diesel. © 2014 Elsevier Ltd.


Lim S.,University of Malaya | Lim S.,Universiti Sains Malaysia | Lee K.T.,Universiti Sains Malaysia
Energy | Year: 2014

Supercritical reactive extraction for Jatropha curcas L. seed was demonstrated to be a viable process for biodiesel production process with high yield and the elimination of separate extraction step. However, because the solid seeds were reacted directly and susceptible to impurities contamination such as water and free fatty acid (FFA), it was important to determine their effects to the extraction efficiency and FAME (fatty acid methyl ester) yield in supercritical reactive extraction. In this study, varying amounts of water (0-40wt.%) and FFA (0-30wt.%) were added to the supercritical reactive extraction process performed at 300°C, 30min effective reaction time, 10MPa and 5.0ml/g methanol to solid ratio. It was found that the supercritical reactive extraction process had a higher tolerance limit for impurities than the non-supercritical acid-catalyzed in situ transesterification process. The former was able to withstand up to 30wt.% of water or FFA without significantly affecting the extraction efficiency and FAME content. A time variation study on the water content showed that the forward hydrolysis of triglyceride molecules to FFA led to a higher reaction rate. Furthermore, the re-hydrolysis reaction of methyl esters to FFA would also occur under a high concentration of methyl esters and water content. A thermal stability study demonstrated that there was no obvious ester decomposition for the process at or below 300°C for a reaction time not exceeding 30min. © 2014 Elsevier Ltd.


Mohamed K.,Universiti Sains Malaysia | Alkaisi M.M.,MacDiarmid Institute for Advanced Materials and Nanotechnology
Nanotechnology | Year: 2013

This work investigates the development of a nanofabrication process to achieve high aspect-ratio nanostructures on quartz substrates using electron beam lithography (EBL) patterning and fluorinated plasma etching processes. An imaging layer of a poly(methyl methacrylate) bi-layer resist was spun coated on quartz substrate and exposed by an e-beam with the designed patterns of sub-100 nm feature sizes using a Raith-150 EBL patterning tool. Additive pattern transfer was employed by depositing a 40 nm thick Nichrome layer on the resist pattern using a metal evaporator which was later lifted off by soaking in acetone. Nichrome was employed as an etch mask and an Oxford Plasmalab 80Plus reactive ion etcher was used for the etching process. The etching process was carried out in a gas mixture of CHF3/Ar with a flow rate ratio of 50/30 sccm, pressure of 20 mTorr, radiofrequency power of 200 W and at room temperature. These etching process parameters were found to achieve a 10 nm min-1 etch rate and tall vertical side walls profile. An aspect-ratio of 10:1 was achieved on 60 nm feature size structures. © 2013 IOP Publishing Ltd.


Ofori-Boateng C.,Universiti Sains Malaysia | Lee K.T.,Universiti Sains Malaysia | Mensah M.,Kwame Nkrumah University Of Science And Technology
Fuel Processing Technology | Year: 2013

In 2010, the total generated municipal solid waste (MSW) in Ghana was 4.5 million tons. About 90% of the total MSW generated is not effectively managed but dumped in unauthorized places creating serious burden on human health. With a population growth rate of about 3.4% per year, Ghana is predicted to face big challenges in waste management. One effective way of managing solid waste is to recover the potent energy from them through waste-to-energy (WTE) plants such as engineered landfilling and controlled incineration. Cost assessment of power generation based on MSW in Ghana showed that the average cost of electricity for landfill gas power plants with already existing closed engineered landfill emerged as the cheapest (USD 0.039/kWh) compared to landfilling without engineered sites and controlled incineration. Moreover, the average domestic employment per megawatt energy generated is higher at approximately 185 for existing engineered landfills compared to the other technologies. Engineered landfill sites are under construction in Ghana whose average power extraction would be between 1 and 2 MW. Thus a potentially sustainable way of managing MSW in Ghana is through the construction of WTE plants to generate electricity. © 2012 Elsevier B.V. All rights reserved.


Zahari Z.,Universiti Sains Malaysia | Ismail R.,Universiti Sains Malaysia | Ismail R.,University of Malaya
Drug Metabolism and Pharmacokinetics | Year: 2014

CYP2D6 polymorphisms show large geographical and interethnic differences. Variations in CYP2D6 activity may impact upon a patient ' s pain level and may contribute to interindividual variations in the response to opioids. This paper reviews the evidence on how CYP2D6 polymorphisms might influence pain sensitivity and clinical response to codeine and tramadol. For example, it is shown that (1) CYP2D6 poor metabolizers (PMs) may be less ef fi cient at synthesizing endogenous morphine compared with other metabolizers. In contrast, ultra-rapid metabolizers (UMs) may be more ef fi cient than other metabolizers at synthesizing endogenous morphine, thus strengthening endogenous pain modulation. Additionally, for codeine and tramadol that are bioactivated by CYP2D6, PMs may undergo no metabolite formation, leading to inadequate analgesia. Conversely, UMs may experience quicker analgesic effects but be prone to higher mu-opioid-related toxicity. The literature suggested the potential usefulness of the determination of CYP2D6 polymorphisms in elucidating serious adverse events and in preventing subsequent inappropriate selection or doses of codeine and tramadol. Notably, even though many studies investigated a possible role of the CYP2D6 polymorphisms on pain sensitivity, pharmacokinetics and pharmacodynamics of these drugs, the results of analgesia and adverse effects are con fl icting. More studies are required to demonstrate genetically determined unresponsiveness and risk of developing serious adverse events for patients with pain and these should involve larger numbers of patients in different population types. Copyright © 2014 by the Japanese Society for the Study of Xenobiotics (JSSX).


Roy R.,Sher-e-Bangla Agricultural University | Chan N.W.,Universiti Sains Malaysia
Environmentalist | Year: 2012

The term 'indicator' is often vague and heterogeneous, and its dynamic characteristics make it highly variable over time and space. Based on reviews and synthesis, this study visualizes phenomena and highlights the trend of indicator selection criteria, development methods, validation evaluation strategies for improvement. In contextualization of the intensification of agriculture and climate change, we proposed a set of indicators for assessing agricultural sustainability in Bangladesh based on theoretically proposed and practically applied indicators by researchers. Also, this article raises several issues of indicator system development and presents a summary after due consideration. Finally, we underline multi-stakeholders' participation in agricultural sustainability assessment. © 2011 Springer Science+Business Media, LLC.


Lee K.T.,Universiti Sains Malaysia | Lim S.,University of Malaya | Pang Y.L.,University of Malaya | Ong H.C.,University of Malaya | Chong W.T.,University of Malaya
Progress in Energy and Combustion Science | Year: 2014

Current world energy usage is trying to gradually shift away from fossil fuels due to the concerns for the climate change and environmental pollutions. Liquid energy from renewable biomass is widely regarded as one of the greener alternatives to partially fulfil the ever-growing energy demand. Contemporary research and technology has been focussing on transforming these bio-resources into efficient liquid and gaseous fuels which are compatible with existing petrochemical energy infrastructure. Due to the wide range of properties and compositions from different types of biomass, there are ample of processing routes available to cater for different demands and requirements. In addition, they can produce multi-component products which can be further upgraded into higher value products. This conceives the idea of bio-refinery where different biomass conversion processes are incorporated and proceed simultaneously at one location. However, the underlying complexity in integrating different processes with varying process conditions will undoubtly incurs prohibitive cost. Consequently, process intensification plays an important role in minimizing both the capital and operating costs associated with process integration in bio-refineries. Recently, process intensification for biodiesel production has been developing rigorously due to increasing demand for cost-cutting measures. Supercritical fluid process allows biodiesel production to be performed without any addition of catalyst. Meanwhile, catalytic in situ or reactive extraction process for biodiesel production successfully combines the extraction and reaction phase together in a single processing unit. In this review, the important characteristics and recent progress on both of the intensification processes for biodiesel production will be critically analyzed. The prospects and recent advances of supercritical reactive extraction (SRE) process which integrates both of the processes will also be discussed. This review will also scrutinize on the methods for these processes to compliment future bio-refinery setup and more efficient utilizing of all of the products generated. © 2014 Elsevier Ltd. All rights reserved.


Lau N.-S.,Universiti Sains Malaysia | Tsuge T.,Tokyo Institute of Technology | Sudesh K.,Universiti Sains Malaysia
Applied Microbiology and Biotechnology | Year: 2011

Burkholderia sp. synthase has been shown to polymerize 3-hydroxybutyrate (3HB), 3-hydroxyvalerate, and 3-hydroxy-4-pentenoic acid monomers. This study was carried out to evaluate the ability of Burkholderia sp. USM (JCM 15050) and its transformant harboring the polyhydroxyalkanoate (PHA) synthase gene of Aeromonas caviae to incorporate the newly reported 3-hydroxy-4-methylvalerate (3H4MV) monomer. Various culture parameters such as concentrations of nutrient rich medium, fructose and 4-methylvaleric acid as well as harvesting time were manipulated to produce P(3HB-co-3H4MV) with different 3H4MV compositions. The structural properties of PHA containing 3H4MV monomer were investigated by using nuclear magnetic resonance and Fourier transform infrared spectroscopy (FTIR). The relative intensities of the bands at 1,183 and 1,228 cm -1 in the FTIR spectra enabled the rapid detection and differentiation of P(3HB-co-3H4MV) from other types of PHA. In addition, the presence of 3H4MV units in the copolymer was found to considerably lower the melting temperature and enthalpy of fusion values compared with poly(3-hydroxybutyrate) (P(3HB)). The copolymer exhibited higher thermo-degradation temperature but similar molecular weight and polydispersity compared with P(3HB). © 2011 Springer-Verlag.


Ahmad F.,Universiti Sains Malaysia | Bateni F.,Universiti Sains Malaysia | Azmi M.,Universiti Sains Malaysia
Geotextiles and Geomembranes | Year: 2010

Triaxial compression tests were conducted to evaluate the response of randomly distributed fibre on the strength of reinforced silty sand. In this study, oil palm empty fruit bunch (OPEFB) fibre was mixed with silty sand soil to investigate the increase of shear strength during triaxial compression. The specimens were tested under drained and undrained conditions with 0.25% and 0.5% content of OPEFB fibres of different lengths (i.e. 15 mm, 30 mm and 45 mm). In addition, OPEFB fibres coated with acrylic butadiene styrene thermoplastic were tested to determine the effect of coating on reinforcement. Inclusion of randomly distributed discrete fibres significantly improved the shear strength of silty sand. Coated OPEFB fibres increased the shear strength of silty sand much more compared to uncoated fibres. Coating fibres increases interface friction between fibre and soil particles by increasing the surface area. Reinforced silty sand containing 0.5% coated fibres of 30 mm length exhibited approximately 25% increase in friction angle and 35% in cohesion under undrained loading conditions compared to those of unreinforced silty sand. The results indicate that the shear strength parameters of the soil-fibre mixture (i.e. Φ′ and c′) can be improved significantly. © 2009 Elsevier Ltd. All rights reserved.


Lew L.-C.,Universiti Sains Malaysia | Liong M.-T.,Universiti Sains Malaysia
Journal of Applied Microbiology | Year: 2013

Probiotics have been extensively reviewed for decades, emphasizing on improving general gut health. Recently, more studies showed that probiotics may exert other health-promoting effects beyond gut well-being, attributed to the rise of the gut-brain axis correlations. Some of these new benefits include skin health such as improving atopic eczema, atopic dermatitis, healing of burn and scars, skin-rejuvenating properties and improving skin innate immunity. Increasing evidence has also showed that bacterial compounds such as cell wall fragments, their metabolites and dead bacteria can elicit certain immune responses on the skin and improve skin barrier functions. This review aimed to underline the mechanisms or the exact compounds underlying the benefits of bacterial extract on the skin based on evidences from in vivo and in vitro studies. This review could be of help in screening of probiotic strains with potential dermal enhancing properties for topical applications. © 2013 The Society for Applied Microbiology.


Chiew Y.L.,Universiti Sains Malaysia | Cheong K.Y.,Universiti Sains Malaysia
Materials Science and Engineering B: Solid-State Materials for Advanced Technology | Year: 2011

Substantial research efforts had been put in developing new ways to produce SiC and its nanostructures. SiC nanostructures showcase excellent hardness, chemical inertness, thermal and electrical properties. With this in mind, many methods have been reported in synthesizing SiC nanostructures. The use of biomass in producing SiC is one of these methods that is promising since it provides an alternative in converting these wastes into something useful and they are a cheap source of silicon and carbon for SiC formation. Thus, this paper will cover the definition of biomass, pyrolysis of biomass in terms of kinetics and processes, effect of different reaction parameters, pre-treatments available and finally SiC recovery process. © 2011 Elsevier B.V. All rights reserved.


Al-attab K.A.,Universiti Sains Malaysia | Zainal Z.A.,Universiti Sains Malaysia
Applied Energy | Year: 2010

The concept of external fired micro gas turbine (EFMGT) using biomass fuels is getting more attention in the last two decades. However, most of the studies were conducted using computer simulation to evaluate the EFMGT systems with a lack of experimental studies. A small scale EFMGT was developed using a vehicular turbocharger as a micro gas turbine. Different micro turbine startup methods were experimentally investigated with maximum turbine inlet temperature and pressure of about 694 °C and 2.1 bar, respectively. The difficulties experienced during the turbocharger engine startup process are reported in this paper. Driving the turbocharger shaft from the compressor side using the air flow hydraulic power was not a sufficient method for the EFMGT unlike the directly fired turbine. The only proven turbine startup method for the EFMGT is the mechanically driven turbine shaft. © 2009 Elsevier Ltd. All rights reserved.


Jawad A.H.,Universiti Sains Malaysia | Nawi M.A.,Universiti Sains Malaysia
Carbohydrate Polymers | Year: 2012

Photocatalytic oxidation of crosslinked chitosan-epichlorohydrin (CS-ECH) film was successfully achieved via an immobilized TiO 2/CS-ECH photocatalyst system on a glass plate. Oxidation process of CS-ECH film was carried out by irradiating the system with a 45-W fluorescent lamp for 10 h in ultra-pure water. The results indicate the formation of carbonyl functional groups and partial elimination of amine groups in the molecular structure of the oxidized CS-ECH film. This oxidized CS-ECH film has different optical properties, ionic conductivity, degree of transparency, swelling index and chemical stability than the fresh CS-ECH film. In the environmental applications, the TiO 2/oxidized-CS-ECH photocatalyst system can have photodegradation and faster mineralization rate of phenol than both fresh TiO 2/CS-ECH and TiO 2/oxidized-CS photocatalyst systems. This simple photocatalyst system, therefore can be considered as an environmental friendly method to oxidize synthetic biopolymer and to improve the photocatalytic efficiency of TiO 2 to treat wastewater. © 2012 Elsevier Ltd.


Lim J.,Carnegie Mellon University | Lim J.,Universiti Sains Malaysia | Lanni C.,Carnegie Mellon University | Evarts E.R.,Carnegie Mellon University | And 3 more authors.
ACS Nano | Year: 2011

Iron oxide cores of 35 nm are coated with gold nanoparticles so that individual particle motion can be tracked in real time through the plasmonic response using dark field optical microscopy. Although Brownian and viscous drag forces are pronounced for nanoparticles, we show that magnetic manipulation is possible using large magnetic field gradients. The trajectories are analyzed to separate contributions from the different types of forces. With field gradients up to 3000 T/m, forces as small as 1.5 fN are detected. © 2011 American Chemical Society.


Hossain M.M.,Universiti Sains Malaysia | Norazmi M.-N.,Universiti Sains Malaysia
BioMed Research International | Year: 2013

Tuberculosis, an infectious disease caused by Mycobacterium tuberculosis (Mtb), remains a major cause of human death worldwide. Innate immunity provides host defense against Mtb. Phagocytosis, characterized by recognition of Mtb by macrophages and dendritic cells (DCs), is the first step of the innate immune defense mechanism. The recognition of Mtb is mediated by pattern recognition receptors (PRRs), expressed on innate immune cells, including toll-like receptors (TLRs), complement receptors, nucleotide oligomerization domain like receptors, dendritic cell-specific intercellular adhesion molecule grabbing nonintegrin (DC-SIGN), mannose receptors, CD14 receptors, scavenger receptors, and FC γ receptors. Interaction of mycobacterial ligands with PRRs leads macrophages and DCs to secrete selected cytokines, which in turn induce interferon- γ - (IFN γ -) dominated immunity. IFN γ and other cytokines like tumor necrosis factor- α (TNF α) regulate mycobacterial growth, granuloma formation, and initiation of the adaptive immune response to Mtb and finally provide protection to the host. However, Mtb can evade destruction by antimicrobial defense mechanisms of the innate immune system as some components of the system may promote survival of the bacteria in these cells and facilitate pathogenesis. Thus, although innate immunity components generally play a protective role against Mtb, they may also facilitate Mtb survival. The involvement of selected PRRs and cytokines on these seemingly contradictory roles is discussed. © 2013 Md. Murad Hossain and Mohd-Nor Norazmi.


Tan K.W.,Universiti Sains Malaysia | Kassim M.J.,Universiti Sains Malaysia | Oo C.W.,Universiti Sains Malaysia
Corrosion Science | Year: 2012

This article describes studies on the modification of mangrove tannin (MT) and catechin (CT) to enhance their corrosion inhibition properties. The inhibitive effect of the starting materials and the chemically modified products on the corrosion of mild steel in 1. M HCl solution was studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). We demonstrated that the chemical modification has successfully enhanced the inhibition efficiency of CT; however reduced that of MT. The disparity in the corrosion inhibitory performances of the modified products was attributed to the inertness of CT towards a complete methylation as compared to MT. © 2012 Elsevier Ltd.


Fan M.-S.,Universiti Sains Malaysia | Abdullah A.Z.,Universiti Sains Malaysia | Bhatia S.,Universiti Sains Malaysia
International Journal of Hydrogen Energy | Year: 2011

Greenhouse gases, carbon dioxide and methane are utilized in the production of hydrogen through carbon dioxide reforming of methane catalyzed by Ni-Co/MgO-ZrO2 catalyst. Design of Experiments (DOE) was used to study the effects of process variables such as, carbon dioxide to methane ratios (1-5), gas hourly space velocity (8400-200,000 mL/g/h), oxygen concentration in the feed (3-8 mol%) and reaction temperature (700-800 °C) over methane conversion and yield of hydrogen. The ANOVA analysis indicated that the effect of each process variable was significant to its respective responses in the proposed quadratic model. The response surface methodology (RSM) was used to find the optimum value of the process variables by maximizing the hydrogen yield in the process model. The optimum space velocity as 145,190 mL/g/h at reaction temperature 749 °C with carbon dioxide to methane ratio of 3 and 7 mol% of oxygen in the feed gave 88 mol% of CH4 conversion and 86 mol% of hydrogen yield, respectively. The experiments were run at the optimum condition gave 87.7 mol% methane conversion and 85.5 mol% of hydrogen yield, which were in good agreement with the simulated values obtained from the model. The catalyst stability and its regeneration characteristics were studied at the optimum condition by monitoring methane conversion and hydrogen yield with time on stream. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.


Fung W.-Y.,Universiti Sains Malaysia | Yuen K.-H.,Universiti Sains Malaysia | Liong M.-T.,Universiti Sains Malaysia
Journal of Agricultural and Food Chemistry | Year: 2011

This study explored the potential of soluble dietary fiber (SDF) from agrowastes, okara (soybean solid waste), oil palm trunk (OPT), and oil palm frond (OPF) obtained via alkali treatment, in the nanoencapsulation of Lactobacillus acidophilus. SDF solutions were amended with 8% poly(vinyl alcohol) to produce nanofibers using electrospinning technology. The spinning solution made from okara had a higher pH value at 5.39 ± 0.01 and a higher viscosity at 578.00 ± 11.02 mPa.s (P < 0.05), which resulted in finer fibers. FTIR spectra of nanofibers showed the presence of hemicellulose material in the SDF. Thermal behavior of nanofibers suggested possible thermal protection of probiotics in heat-processed foods. L. acidophilus was incorporated into the spinning solution to produce nanofiber-encapsulated probiotic, measuring 229-703 nm, visible under fluorescence microscopy. Viability studies showed good bacterial survivability of 78.6-90% under electrospinning conditions and retained viability at refrigeration temperature during the 21 day storage study. © 2011 American Chemical Society.


Akhtarkavan E.,Universiti Sains Malaysia | Salleh M.F.M.,Universiti Sains Malaysia
IEEE Transactions on Image Processing | Year: 2012

Multiple description (MD) coding has been a popular choice for robust data transmission over the unreliable network channels. Lattice vector quantization provides lower computation for efficient data compression. In this paper, a new MD coinciding lattice vector quantizer (MDCLVQ) is presented. The design of the quantizer is based on coinciding 2-D hexagonal sublattices. The coinciding sublattices are geometrically similar sublattices, with the same index but generated by different generator matrices. A novel labeling algorithm based on the hexagonal coinciding sublattices is also developed. Performance results of the MDCLVQ scheme, together with the new labeling algorithm applied to standard test images, show improvements of the central and side decoders, as compared with the renowned techniques for several test images. © 2011 IEEE.


Yusoff M.S.B.,Universiti Sains Malaysia
International Medical Journal | Year: 2011

Objective: Studies have revealed that the prevalence of distress among medical student is higher compared to normal population and the main stressor was academic especially examinations. This study is interested in gathering data objectively on the impact of summative examination on the USM medical students' mental health. Methods: This is a comparative pre and post cross-sectional study. A total of 260 first year medical students were selected as respondents for the first data collection whereas only 100 medical students were randomly selected for the second data collection. The 12 items General Health Questionnaire (GHQ-12) and Medical Student Stressor Questionnaire (MSSQ) were administered to measure stress level and stressor of the medical students. Stress levels of medical students were measured at two occasions; eight months prior to the examination as the baseline stress level and just after the last paper of the examination as the examination stress level. Result: A total of 213 students responded in the first session and 99 students in the second session. This study showed that the percentage of distressed medical students was significantly increased during summative examination; the baseline percentage of distressed medical students was 26.29% and the percentage of distressed medical students during the examination was 58.59% (X2 = 30.2, p < 0.001). The mean stress level was found to be significantly increased during the examination; the baseline mean stress level was 2.41 and the mean stress level during examination was 4.39 (t = -5.72, p < 0.001). Binary logistic regression showed that medical students were at 3.97 time more risk to develop distressed compared to before the examination (Wald = 28.82, OR (CI 95%) = 3.97 (2.40, 6.56), p < 0.001). Conclusion: The percentage of distressed medical students during the examination was significantly higher compared to before the examination. The mean stress level was significantly high during the examination. Medical students were at high risk to develop distress during summative examination period. © 2011 Japan International Cultural Exchange Foundation & Japan Health Sciences University.


Mahadi M.I.,Universiti Sains Malaysia | Palaniandy S.,Universiti Sains Malaysia
International Journal of Mineral Processing | Year: 2010

Dolomitic talc was milled in a mortar mill by varying the milling time, solid content, and vertical stress. The milled samples exhibited massive particle size reduction and came to a threshold value around 4 μm, with wider particle size distribution. The breakage mechanism of the dolomite and talc phase was influenced by hardness, crystallographic structure, and Young's Modulus. The milled particles underwent massive mechanochemical effect where the degree of crystallinity ranged from 40% to 50%. The variation of lattice parameters of both phases was influenced by mill operational parameters and breakage mechanism of the particles in the mill. © 2010 Elsevier B.V. All rights reserved.


Garba Z.N.,Universiti Sains Malaysia | Rahim A.A.,Universiti Sains Malaysia
Journal of Analytical and Applied Pyrolysis | Year: 2014

Potassium oxalate was used as an activating agent for the preparation of activated carbons using Prosopic africana seed hulls (PASH) as a newly discovered precursor. The preparation conditions were optimized by using central composite design (CCD), a subset of response surface methodology (RSM) to maximize the activated carbon yield as well as percentage removal of 4-chloroguaiacol (4CG). The activated carbon was produced at the optimum conditions of 780 °C activation temperature, 63 min activation time and 3.19 IR resulting in 91.65% of 4CG removal and 21.43% yield. The experimental values obtained were in good agreement with the values predicted from the models with relatively small errors. The activated carbon prepared under optimum conditions was mesoporous with BET surface area, Langmuir surface area, total pore volume and the pore size of 1095.56 m2/g, 1205.70 m2/g, 0.50 cm3/g and 3.08 nm respectively. Scanning electron microscopy (SEM) and energy dispersive X-ray microanalysis (EDX) were used to investigate the obtained optimal activated carbon. The results revealed that PASH could be recommended as a promising effective precursor for producing activated carbons with excellently developed pores, good yield and potentially desirable 4CG percentage removal. © 2014 Elsevier B.V.


Tabassi A.A.,Universiti Sains Malaysia | Ramli M.,Universiti Sains Malaysia | Bakar A.H.A.,Universiti Sains Malaysia
International Journal of Project Management | Year: 2012

A well-organised human resource development programme is a critical strategy for construction companies, as in the coming years, human capital will increasingly play a significant role in organisational success. Based on a combination of the literature appraisal and questionnaire survey, the study explores the correlation of HRD strategies in employee training and motivation practices with teamwork improvement and task efficiency in construction projects. The research analysis was completed on a sample population of 107 individuals within nominated construction firms in Iran. The analysis methods in this research were mainly descriptive and regression-based analyses and the type of investigation was a co-relational study. The research found the relationship of training and motivation practices with teamwork improvement and task efficiency in the respondents' companies by exploring the two generated research models. © 2011 Elsevier Ltd.


Khan I.,Universiti Sains Malaysia | Poh B.T.,Universiti Sains Malaysia
Journal of Polymers and the Environment | Year: 2012

The effect of molecular weight and testing rate on peel and shear strength of epoxidized natural rubber (ENR-50)-based adhesive was investigated using petro resin as the tackifier. Toluene and polyethylene terephthalate were used as the solvent and substrate respectively. Peel and shear strength were determined by a Llyod Adhesion Tester operating at different rates of testing. Result shows that peel strength and shear strength increases up to an optimum molecular weight of 4. 2 × 10 4 g/mol of ENR-50. This observation is attributed to the combined effects of wettability and mechanical strength of rubber for peel strength. For shear strength, it is ascribed to the optimum cohesive and adhesive strength. Both peel strength and shear strength increases with increasing rate of testing, an observation which is associated to the viscoeslastic response of the adhesive. Thermal study, SEM and FTIR study confirms the miscibility of tackifier with ENR-50. © 2011 Springer Science+Business Media, LLC.


Eh A.L.-S.,Universiti Sains Malaysia | Teoh S.-G.,Universiti Sains Malaysia
Ultrasonics Sonochemistry | Year: 2012

Lycopene extraction was carried out via the ultrasonic assisted extraction (UAE) with response surface methodology (RSM). Sonication enhanced the efficiency of relative lycopene yield (enhancement of 26% extraction yield of lycopene in 6 replications at 40.0 min, 40.0 °C and 70.0% v/w in the presence of ultrasound), lowered the extraction temperature and shortened the total extraction time. The extraction was applied with the addition of oxygen-free nitrogen flow and change of water route during water bath sonication. The highest relative yield of lycopene obtained was 100% at 45.0 °C with total extraction time of 50.0 min (30:10:10) and ratio of solvent to freeze-dried tomato sample (v/w) of 80.0:1. Optimisation of the lycopene extraction had been performed, giving the average relative lycopene yield of 99% at 45.6 min, 47.6 °C and ratio of solvent to freeze-dried tomato sample (v/w) of 74.4:1. From the optimised model, the average yield of all-trans lycopene obtained was 5.11 ± 0.27 mg/g dry weight. The all-trans lycopene obtained from the high-performance liquid chromatography (HPLC) chromatograms was 96.81 ± 0.81% with 3.19 ± 0.81% of cis-lycopenes. The purity of total-lycopene obtained was 98.27 ± 0.52% with β-carotene constituted 1.73 ± 0.52% of the extract. The current improved, UAE of lycopene from tomatoes with the aid of RSM also enhanced the extraction yield of trans-lycopene by 75.93% compared to optimised conventional method of extraction. Hence, the current, improved UAE of lycopene promotes the extraction yield of lycopene and at the same time, minimises the degradation and isomerisation of lycopene. © 2011 Elsevier B.V. All rights reserved.


Pang Y.L.,Universiti Sains Malaysia | Abdullah A.Z.,Universiti Sains Malaysia
Ultrasonics Sonochemistry | Year: 2012

Sonocatalytic degradation of various organic dyes (Congo Red, Reactive Blue 4, Methyl Orange, Rhodamine B and Methylene Blue) catalyzed by powder and nanotubes TiO 2 was studied. Both catalysts were characterized using transmission electron microscope (TEM), surface analyzer, Raman spectroscope and thermal gravimetric analyzer (TGA). Sonocatalytic activity of powder and nanotubes TiO 2 was elucidated based on the degradation of various organic dyes. The former catalyst was favorable for treatment of anionic dyes, while the latter was more beneficial for cationic dyes. Sonocatalytic activity of TiO 2 nanotubes could be up to four times as compared to TiO 2 powder under an ultrasonic power of 100 W and a frequency of 42 kHz. This was associated with the higher surface area and the electrostatic attraction between dye molecules and TiO 2 nanotubes. Fourier transform-infrared spectrometer (FT-IR) was used to identify changes that occurred on the functional group in Rhodamine B molecules and TiO 2 nanotubes after the reaction. Sonocatalytic degradation of Rhodamine B by TiO 2 nanotubes apparently followed the Langmuir-Hinshelwood adsorption kinetic model with surface reaction rate of 1.75 mg/L min. TiO 2 nanotubes were proven for their high potential to be applied in sonocatalytic degradation of organic dyes. © 2011 Elsevier B.V. All rights reserved.


Lai C.W.,Universiti Sains Malaysia | Sreekantan S.,Universiti Sains Malaysia
Micro and Nano Letters | Year: 2012

Adding hydrogen peroxide (H 2O 2) for the fast formation of titanium dioxide (TiO 2) nanotube arrays produce smooth and clean TiO 2 nanotubes without bundling and cracking problems. The nanotube formation rate accelerated after the periodical addition of H 2O 2 at different intervals. Adding H 2O 2 at 10min intervals formed longer nanotubes (13m) with larger pore diameters (140nm). These novel TiO 2 nanotubes exhibited optimal photocurrent density (1.8mA/cm 2) and 3.8 photoconversion efficiency because of high crystallinity with numerous oxygen vacancies in the large pore diameters allowed for better light absorption and good interaction between the electrolytes and TiO 2 nanotubes. © 2012 The Institution of Engineering and Technology.


Ramdan D.,Universiti Sains Malaysia | Abdullah M.Z.,Universiti Sains Malaysia | Yusop N.M.,Universiti Sains Malaysia
International Communications in Heat and Mass Transfer | Year: 2012

The current paper analyzes the effect of outlet vent arrangements on the air traps and pressure distribution of a stacked-chip scale package (S-CSP) during encapsulation. A three-dimensional model of S-CSP is created using GAMBIT and analyzed using FLUENT code. In the molding process, the epoxy molding compound flow behavior calculated using the Castro-Macosko viscosity model by considering the curing effect, and the volume of fluid technique are applied for flow front tracking. The viscosity model is written in C language and compiled using User-Defined Function in FLUENT code. Three different types of outlet vent arrangement are considered in the analysis, namely, Type A, Type B, and Type C. Type A, which has the minimum outlet vent area, shows the minimum air trap and the highest average pressure distribution. The simulation results of the flow front profiles agree well with previous experimental results. © 2012 Elsevier Ltd.


Quah H.J.,Universiti Sains Malaysia | Cheong K.Y.,Universiti Sains Malaysia
ACS Applied Materials and Interfaces | Year: 2014

A systematic investigation was carried out by incorporating an ultrathin aluminum oxide (Al2O3) as an interlayer between yttrium oxide (Y2O3) passivation layer and GaN substrate. The sandwiched samples were then subjected to postdeposition annealing in oxygen ambient from 400 to 800 °C. The Al2O3 interlayer was discovered to play a significant role in slowing down inward diffusion of oxygen through the Y2O3 passivation layer as well as in impeding outward diffusion of Ga3+ and N3- from the decomposed GaN surface. These beneficial effects have suppressed subsequent formation of interfacial layer. A mechanism in association with the function of Al 2O3 as an interlayer was suggested and discussed. The mechanism was explicitly described on the basis of the obtained results from X-ray diffraction, X-ray photoelectron spectroscopy, energy-filtered transmission electron microscopy (TEM), high resolution TEM, and electron energy loss spectroscopy line scan. A correlation between the proposed mechanism and metal-oxide-semiconductor characteristics of Y2O3/Al 2O3/GaN structure has been proposed. © 2014 American Chemical Society.


Ofori-Boateng C.,Universiti Sains Malaysia | Lee K.T.,Universiti Sains Malaysia
Applied Thermal Engineering | Year: 2014

In this study, thermo-environmental sustainability of an oil palm-based biorefinery concept for the co-production of cellulosic ethanol and phytochemicals from oil palm fronds (OPFs) was evaluated based on exergetic life cycle assessment (ExLCA). For the production of 1 tonne bioethanol, the exergy content of oil palm seeds was upgraded from 236 MJ to 77,999 MJ during the farming process for OPFs production. Again, the high exergy content of the OPFs was degraded by about 62.02% and 98.36% when they were converted into cellulosic ethanol and phenolic compounds respectively. With a total exergy destruction of about 958,606 MJ (internal) and 120,491 MJ (external or exergy of wastes), the biorefinery recorded an overall exergy efficiency and thermodynamic sustainability index (TSI) of about 59.05% and 2.44 per tonne of OPFs' bioethanol respectively. Due to the use of fossil fuels, pesticides, fertilizers and other toxic chemicals during the production, the global warming potential (GWP = 2265.69 kg CO2 eq.), acidification potential (AP = 355.34 kg SO2 eq.) and human toxicity potential (HTP = 142.79 kg DCB eq.) were the most significant environmental impact categories for a tonne of bioethanol produced in the biorefinery. The simultaneous saccharification and fermentation (SSF) unit emerged as the most exergetically efficient (89.66%), thermodynamically sustainable (TSI = 9.67) and environmentally friendly (6.59% of total GWP) production system. © 2013 Elsevier Ltd. All rights reserved.


Al-Tamimi N.A.,Universiti Sains Malaysia | Fadzil S.F.S.,Universiti Sains Malaysia
Procedia Engineering | Year: 2011

The present study focuses on the effect of shading devices on the indoor temperature of high-rise residential buildings in the hot-humid climate of Malaysia. Several methods can be employed to improve indoor thermal environment, including using a reflective glazing system, using light colors for external surfaces, and using the appropriate thermal properties of external walls and roofs. However, before using any of these methods, it is important to have an optimum shading device to reduce the solar radiation absorption that leads to an overheated indoor environment and an increase in cooling energy loads. Therefore, the main objective of the current paper is to find the extent of a building's solar heat gain and, consequently, the indoor air temperature that is influenced by the external shading devices. A computerized simulation tool (IES〈VE〉) is used to carry out the investigation, taking Penang as the empirical background of the hot-humid climate. The results indicate that egg-crate shading has a significant impact on decreasing discomfort hours compared with other shading types. © 2011 Published by Elsevier Ltd.


Quah H.J.,Universiti Sains Malaysia | Cheong K.Y.,Universiti Sains Malaysia | Hassan Z.,Universiti Sains Malaysia | Lockman Z.,Universiti Sains Malaysia
IEEE Transactions on Electron Devices | Year: 2011

This paper presents the effects of postdeposition annealing temperatures (400, 600, 800, and 1000 °C in oxygen ambient on the metal-organic decomposed CeO2 films spin coated on an n-type GaN substrate. The compositions, structures, and morphologies of these samples are revealed by X-ray diffraction (XRD), field-emission scanning electron microscopy, and an atomic force microscope. XRD analysis discloses the presence of CeO2 films, α CeO3, and an interfacial layer of β-Ga23. The formation of α-C eO2 is due to the phase transformation of C eO2, whereas the β-Ga22O3 interfacial layer is formed due to the inward diffusion of the released oxygen from CeO2 reacting with decomposed GaN. These characterization results are then correlated with the metal-oxide-semiconductor characteristics of the CeO2 gate annealed at different temperatures. It has been demonstrated that oxide annealed at 1000 °C shows the lowest semiconductoroxide interface-trap density, effective oxide charge, and the highest dielectric breakdown field. © 2010 IEEE.


Tan K.T.,Universiti Sains Malaysia | Lee K.T.,Universiti Sains Malaysia | Mohamed A.R.,Universiti Sains Malaysia
Energy | Year: 2011

Disposal of waste palm cooking oil (WPCO) via an environmental-friendly route is of major importance in the quest for sustainable development. In this study, WPCO was utilized instead of refined vegetable oils as the source of triglycerides for biodiesel production. WPCO contains several impurities, such as water and free fatty acids, which limit its application in catalytic transesterification processes. Consequently, a catalyst-free process using supercritical methanol was employed to investigate the potential of WPCO as an economical feedstock for biodiesel production. The parameters that influence the reaction, including reaction time, temperature and the molar ratio of alcohol to oil, were investigated. For comparison purposes, refined palm oil (RPO) was also subjected to supercritical methanol reaction and it was found that both processes produced comparable optimum yields of 80% at their respective optimum conditions. Hence, it can be concluded that WPCO has high potential as an economical and practical future source of biodiesel. © 2010 Elsevier Ltd.


Ahmad A.L.,Universiti Sains Malaysia | Yasin N.H.M.,Universiti Sains Malaysia | Derek C.J.C.,Universiti Sains Malaysia | Lim J.K.,Universiti Sains Malaysia
Renewable and Sustainable Energy Reviews | Year: 2011

Of the three generations of biodiesel feedstocks described in this paper, food crops, non-food crops and microalgae-derived biodiesel, it was found that the third generation, microalgae, is the only source that can be sustainably developed in the future. Microalgae can be converted directly into energy, such as biodiesel, and therefore appear to be a promising source of renewable energy. This paper presents a comparison between the use of microalgae and palm oil as biodiesel feedstocks. It was found that microalgae are the more sustainable source of biodiesel in terms of food security and environmental impact compared to palm oil. The inefficiency and unsustainability of the use of food crops as a biodiesel source have increased interest in the development of microalgae species to be used as a renewable energy source. In this paper, the main advantages of using microalgae for biodiesel production are described in comparison with other available feedstocks, primarily palm oil. © 2010 Elsevier Ltd.


Khalil M.I.,Universiti Sains Malaysia | Sulaiman S.A.,Universiti Sains Malaysia
African Journal of Traditional, Complementary and Alternative Medicines | Year: 2010

Honey is rich in phenolic compounds, which act as natural antioxidants and are becoming increasingly popular because of their potential role in contributing to human health. A wide range of phenolic constituents is present in honey like quercetin, caffeic acid phenethyl ester (CAPE), acacetin, kaempferol, galangin which have promising effect in the treatment of cardiovascular diseases. Many epidemiological studies have shown that regular intake of phenolic compounds is associated with reduced risk of heart diseases. In coronary heart disease, the protective effects of phenolic compounds include mainly antithrombotic, anti-ischemic, anti-oxidant, and vasorelaxant. It is suggested that flavonoids decrease the risk of coronary heart disease by three major actions: improving coronary vasodilatation, decreasing the ability of platelets in the blood to clot, and preventing low-density lipoproteins (LDLs) from oxidizing. In this review paper, we discussed the preventive role of polyphenols of honey against cardiovascular diseases.


Al-attab K.A.,Universiti Sains Malaysia | Zainal Z.A.,Universiti Sains Malaysia
Applied Energy | Year: 2011

The combustion difficulties for low heating value (LHV) gases derived from biomass fuels via a gasification process have led to more investigations into LHV gas combustors. Cyclone combustors provide good air/fuel mixing with long residence times. In this study, a small-scale pressurized cyclone combustor (PCC) was designed and optimized using computational fluid dynamics (CFD) simulation. The PCC, along with a turbocharger-based, two-stage microturbine engine, was first characterized experimentally with liquefied petroleum gas (LPG) fuel and then with both LPG and LHV gas derived from biomass in dual-fuel mode. The combustor achieved ultra-low CO and NO. x emissions of about 5 and 7. ppm, respectively, for LPG fuel and of about 55 and 12. ppm, respectively, in dual-fuel mode at the maximum second-stage turbine speed of 26,000. rpm with stable turbine operation. © 2010 Elsevier Ltd.


Jawaid M.,Universiti Sains Malaysia | Khalil H.P.S.A.,Universiti Sains Malaysia | Bakar A.A.,Universiti Sains Malaysia | Khanam P.N.,Universiti Sains Malaysia
Materials and Design | Year: 2011

Tri layer hybrid composites of oil palm empty fruit bunches (EFB) and jute fibres was prepared by keeping oil palm EFB as skin material and jute as the core material and vice versa. The chemical resistance, void content and tensile properties of oil palm EFB/Jute composites was investigated with reference to the relative weight of oil palm EFB/Jute, i.e. 4:1, the fibre loading was optimized and different layering pattern were investigated. It is found from the chemical resistance test that all the composites are resistant to various chemicals. It was observed that marked reduction in void content of hybrid composites in different layering pattern. From the different layering pattern, the tensile properties were slightly higher for the composite having jute as skin and oil palm EFB as core material. Scanning electron microscopy (SEM) was used to study tensile fracture surfaces of different composites. © 2010 Elsevier Ltd.


Yusoff M.,Universiti Sains Malaysia | Othman R.,Universiti Sains Malaysia | Hussain Z.,Universiti Sains Malaysia
Materials and Design | Year: 2011

Elemental powders of copper (Cu), tungsten (W) and graphite (C) were mechanically alloyed in a planetary ball mill with different milling durations (0-60h), compacted and sintered in order to precipitate hard tungsten carbide particles into a copper matrix. Both powder and sintered composite were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) and assessed for hardness and electrical conductivity to investigate the effects of milling time on formation of nanostructured Cu-WC composite and its properties. No carbide peak was detected in the powder mixtures after milling. Carbide WC and W2C phases were precipitated only in the sintered composite. The formation of WC began with longer milling times, after W2C formation. Prolonged milling time decreased the crystallite size as well as the internal strain of Cu. Hardness of the composite was enhanced but electrical conductivity reduced with increasing milling time. © 2011 Elsevier Ltd.


Pang A.L.,Universiti Sains Malaysia | Ismail H.,Universiti Sains Malaysia
BioResources | Year: 2013

The effects of kenaf (KNF) loading and 3-aminopropyltriethoxysilane (APTES) on the tensile properties, water uptake, and thermal properties of KNF-filled polypropylene (PP)/waste pulverized tire (WPT) composites were investigated. The composites were prepared using a Thermo Haake Polydrive internal mixer, where KNF loadings (0, 5, 10, 15, 20 phr) and constant PP/WPT (70/30) were used. The results showed that the tensile modulus and water uptake increased, but tensile strength and elongation at break decreased, with increased KNF loading. The composites with APTES exhibited a higher tensile strength and tensile modulus, but lower elongation at break and water uptake than composites without APTES. The presence of APTES enhanced the interfacial adhesion between PP/WPT matrices and KNF. Thermal stability of PP/WPT/KNF composites increased with KNF loading, and was found slightly higher, but insignificant for composites with APTES. Fourier transform infrared (FTIR) spectra analysis was performed to study the interactions among the PP, WPT, KNF, and the ethoxy functional groups in APTES.


Kong N.S.P.,Universiti Sains Malaysia | Ibrahim H.,Universiti Sains Malaysia
Computers and Electrical Engineering | Year: 2011

Although local histogram equalization (LHE) can be used to emphasize local content in an image, several problems are associated with it. First, LHE tends to amplify speckle noise. Second, this method is not able to preserve the shape of the input histogram, which means the lost of information. Previous literatures also do not give any suggestion on selecting a proper window size for LHE. Therefore, an extension to LHE, which we call as multiple layers block overlapped histogram equalization (MLBOHE), has been introduced. This method consists of three stages, which are enhancement stage, noise reduction stage, and merging stage. Experimental results show that MLBOHE is better than some well-known histogram equalization based local enhancement methods. © 2010 Elsevier Ltd. All rights reserved.


Hosseini S.M.,Universiti Sains Malaysia | Aziz H.A.,Universiti Sains Malaysia
Bioresource Technology | Year: 2013

The effects of thermochemical pretreatment and continuous thermophilic conditions on the composting of a mixture of rice straw residue and cattle manure were investigated using a laboratory-scale composting reactor. Results indicate that the composting period of rice straw can be shortened to less than 10. days by applying alkali pre-treatment and continuous thermophilic composting conditions. The parameters obtained on day 9 of this study are similar to the criteria level published by the Canadian Council of Ministers of the Environment. The moisture content, organic matter reduction, pH level, electrical conductivity, total organic carbon reduction, soluble chemical oxygen demand reduction, total Kjeldahl nitrogen, carbon-to-nitrogen ratio, and germination index were 62.07%, 16.99%, 7.30%, 1058. μS/cm, 17.00%, 83.43%, 2.06%, 16.75%, and 90.33%, respectively. The results of this study suggest that the application of chemical-biological integrated processes under thermophilic conditions is a novel method for the rapid degradation and maturation of rice straw residue. © 2013 Elsevier Ltd.


Olutoye M.A.,Universiti Sains Malaysia | Hameed B.H.,Universiti Sains Malaysia
Bioresource Technology | Year: 2013

An active heterogeneous Al2O3 modified MgZnO (MgZnAlO) catalyst was prepared and the catalytic activity was investigated for the transesterification of different vegetable oils (refined palm oil, waste cooking palm oil, palm kernel oil and coconut oil) with methanol to produce biodiesel. The catalyst was characterized by using X-ray diffraction, Fourier transform infrared spectra, thermo gravimetric and differential thermal analysis to ascertain its versatility. Effects of important reaction parameters such as methanol to oil molar ratio, catalyst dosage, reaction temperature and reaction time on oil conversion were examined. Within the range of studied variability, the suitable transesterification conditions (methanol/oil ratio 16:1, catalyst loading 3.32 wt.%, reaction time 6h, temperature 182°C), the oil conversion of 98% could be achieved with reference to coconut oil in a single stage. The catalyst can be easily recovered and reused for five cycles without significant deactivation. © 2013 Elsevier Ltd.


Zainuddin Z.,Universiti Sains Malaysia | Ong P.,Universiti Sains Malaysia
Expert Systems with Applications | Year: 2011

Properly designing a wavelet neural network (WNN) is crucial for achieving the optimal generalization performance. In this paper, two different approaches were proposed for improving the predictive capability of WNNs. First, the types of activation functions used in the hidden layer of the WNN were varied. Second, the proposed enhanced fuzzy c-means clustering algorithm - specifically, the modified point symmetry-based fuzzy c-means (MSFCM) algorithm - was employed in selecting the locations of the translation vectors of the WNN. The modified WNN was then applied to heterogeneous cancer classification using four different microarray benchmark datasets. The comparative experimental results showed that the proposed methodology achieved an almost 100% classification accuracy in multiclass cancer prediction, leading to superior performance with respect to other clustering algorithms. Subsequently, performance comparisons with other classifiers were made. An assessment analysis showed that this proposed approach outperformed most of the other classifiers. © 2011 Elsevier Ltd. All rights reserved.


Ang L.W.,Universiti Sains Malaysia
Proceedings of CHIuXiD 2016, the 2nd International Human Computer Interaction and User Experience Conference in Indonesia: Bridging the Gaps in the HCI and UX World | Year: 2016

A mentor-mentee consultation system (MEMOC) for higher education institutions is proposed based on a multidimensional conceptualization of social presence and Online Instructional Consultation (OICon) model. The objective of the MEMOC system is to develop the problem-based mentoring to provide the counselling support to undergraduate and postgraduate students. We utilize the user personas to represent both mentor and mentees' profiles by categorizing them into three types of user personas, namely a) mentor b) active students, c) passive students. Furthermore, we implemented the JOHARI window, otherwise known as "self-disclosure matrix", to explain on the mentor's role in providing feedback, self-disclosure, and to build the mentor-mentee relationships with mentees. A sample of eight lecturers, tutors and 40 students are involved in user testing. These students and lecturers were required to test the MEMOC system by performing a series of tasks. Overall, the descriptive findings show that students and lecturers are satisfied with the MEMOC system. Respondents agreed that they will use the MEMOC system in the future in terms of perceived usefulness (PU) and Attitude. © 2016 ACM.


Foo K.Y.,Universiti Sains Malaysia | Lee L.K.,Universiti Sains Malaysia | Hameed B.H.,Universiti Sains Malaysia
Bioresource Technology | Year: 2013

The preparation of tamarind fruit seed granular activated carbon (TSAC) by microwave induced chemical activation for the adsorptive treatment of semi-aerobic landfill leachate has been attempted. The chemical and physical properties of TSAC were examined. A series of column tests were performed to determine the breakthrough characteristics, by varying the operational parameters, hydraulic loading rate (5-20. mL/min) and adsorbent bed height (15-21. cm). Ammonical nitrogen and chemical oxygen demand (COD), which provide a prerequisite insight into the prediction of leachate quality was quantified. Results illustrated an encouraging performance for the adsorptive removal of ammonical nitrogen and COD, with the highest bed capacity of 84.69 and 55.09. mg/g respectively, at the hydraulic loading rate of 5. mL/min and adsorbent bed height of 21. cm. The dynamic adsorption behavior was satisfactory described by the Thomas and Yoon-Nelson models. The findings demonstrated the applicability of TSAC for the adsorptive treatment of landfill leachate. © 2013 Elsevier Ltd.


Foo K.Y.,Universiti Sains Malaysia | Lee L.K.,Universiti Sains Malaysia | Hameed B.H.,Universiti Sains Malaysia
Bioresource Technology | Year: 2013

This study evaluates the sugarcane bagasse derived activated carbon (SBAC) prepared by microwave heating for the adsorptive removal of ammonical nitrogen and orthophosphate from the semi-aerobic landfill leachate. The physical and chemical properties of SBAC were examined by pore structural analysis, scanning electron microscopy, Fourier transform infrared spectroscopy and elemental analysis. The effects of adsorbent dosage, contact time and solution pH on the adsorption performance were investigated in a batch mode study at 30. °C. Equilibrium data were favorably described by the Langmuir isotherm model, with a maximum monolayer adsorption capacity for ammonical nitrogen and orthophosphate of 138.46 and 12.81. mg/g, respectively, while the adsorption kinetic was best fitted to the pseudo-second-order kinetic model. The results illustrated the potential of sugarcane bagasse derived activated carbon for the adsorptive treatment of semi-aerobic landfill leachate. © 2013 Elsevier Ltd.


Pang Y.L.,Universiti Sains Malaysia | Abdullah A.Z.,Universiti Sains Malaysia
Applied Catalysis B: Environmental | Year: 2013

Fe-doped titanium dioxide (TiO2) nanotubes catalyst with large specific surface area and low band gap energy were successfully synthesized using sol-gel followed by hydrothermal method. The activity of the catalyst was assessed by examining the treatment of real textile wastewater through combined adsorption and heterogeneous sonocatalysis. Fe-doped TiO2 nanotubes exhibited better removal efficiency in the case of pre-adsorption followed by sonocatalytic reaction as compared to the simultaneous adsorption and sonocatalysis system. Pre-adsorption on TiO2 nanotubes was found to promote sonocatalytic degradation and the latter process could be considered as a surface-catalyzed reaction. Effect of the solution pH (3-11), catalyst dosage (2-10g/L) and hydrogen peroxide (H2O2) dosage (20-80mM) on the adsorption-sonocatalysis for the treatment of a real textile wastewater were investigated in detail. The best degradation efficiency can be achieved at solution pH of 3, 6g/L of Fe-doping, 40mM of H2O2, an ultrasonic frequency of 35kHz and an output power of 50W after 1h of adsorption followed by 3h of ultrasonic irradiation under continuous aeration. The color, COD and TOC removals were 79.9%, 59.4% and 49.8%, respectively. In short, adsorption followed by sonocatalytic degradation in the presence of Fe-doped TiO2 nanotubes showed great potential for efficient treatment of real textile wastewater. © 2012 Elsevier B.V.


Foo K.Y.,Universiti Sains Malaysia | Hameed B.H.,Universiti Sains Malaysia
Bioresource Technology | Year: 2013

In this work, preparation of granular activated carbon from oil palm biodiesel solid residue, oil palm shell (PSAC) by microwave assisted KOH activation has been attempted. The physical and chemical properties of PSAC were characterized using scanning electron microscopy, volumetric adsorption analyzer and elemental analysis. The adsorption behavior was examined by performing batch adsorption experiments using methylene blue as dye model compound. Equilibrium data were simulated using the Langmuir, Freundlich and Temkin isotherm models. Kinetic modeling was fitted to the pseudo-first-order, pseudo-second-order and Elovich kinetic models, while the adsorption mechanism was determined using the intraparticle diffusion and Boyd equations. The result was satisfactory fitted to the Langmuir isotherm model with a monolayer adsorption capacity of 343.94. mg/g at 30 °C. The findings support the potential of oil palm shell for preparation of high surface area activated carbon by microwave assisted KOH activation. © 2012 Elsevier Ltd.


Appaturi J.N.,Universiti Sains Malaysia | Adam F.,Universiti Sains Malaysia
Applied Catalysis B: Environmental | Year: 2013

MCM-41 was successfully immobilized with imidazole using 3-chloropropyltriethoxysilane (CPTES) as the anchoring agent followed by alkylation with 1,2-dibromoethane at 110°C. The resulting catalyst was designated as MCM-41-Imi/Br. TEM showed the catalyst had ordered mesoporous straight-channels with average wall thickness of 2.14nm and average pore size of 1.56nm. The 29Si MAS NMR analysis confirmed the presence of T2, T3, Q3 and Q4 silicon centers. The 13C MAS NMR showed that MCM-41-Imi/Br had three chemical shifts corresponding to the three carbon atoms of the propyl group. The aromatic imidazole peaks were detected at 110-140ppm. The catalyst was used in the solvent-less synthesis of styrene carbonate (SC) from CO2 and styrene oxide (SO) under ambient conditions. It was demonstrated that the synergistic effect due to the stronger nucleophilicity of Br- and amine in the catalyst could lead to a maximum selectivity of 99.1%. Based on the results, a plausible reaction mechanism was proposed for the catalytic reaction. The catalyst could be recovered and reused several times without significant loss in the catalytic activity. © 2013 Elsevier B.V.


Lim S.,Universiti Sains Malaysia | Lee K.T.,Universiti Sains Malaysia
Bioresource Technology | Year: 2013

In this study, optimization of supercritical reactive extraction directly from Jatropha seeds in a high pressure batch reactor using Response Surface Methodology (RSM) coupled with Central Composite Rotatable Design (CCRD) was performed. Four primary variables (methanol to solid ratio (SSR), reaction temperature, time and CO2 initial pressure) were investigated under the proposed constraints. It was found that all variables had significant effects towards fatty acid methyl esters (FAME) yield. Moreover, three interaction effects between the variables also played a major role in influencing the final FAME yield. Optimum FAME yield at 92.0wt.% was achieved under the following conditions: 5.9 SSR, 300°C, 12.3min and 20bar CO2. Final FAME product was discovered to fulfil existing international standard. Preliminary characterization analysis proved that the solid residue can be burnt as solid fuel in the form of biochar while the liquid product can be separated as specialty chemicals or burned as bio-oil for energy production. © 2013 Elsevier Ltd.


Mohamad N.,Universiti Sains Malaysia | Zuharah W.F.,Universiti Sains Malaysia
Tropical Biomedicine | Year: 2014

Toxorhynchites splendens larvae are a natural predator of dengue vector mosquito larvae, Aedes albopictus. This study was carried out to evaluate the predation rate of Tx. splendens third instar larvae on Ae. albopictus larvae in 24 h. Each predator was offered prey at a density between 10 to 50 individuals. Predation rate of Tx. splendens were also tested with two manipulated factors; various types of container and different water volumes. The experiment was eva