Kuala Selangor, Malaysia
Kuala Selangor, Malaysia

The National University of Malaysia Pusat Perubatan Universiti Kebangsaan Malaysia is located in Cheras and also has a branch campus in Kuala Lumpur. There are 17,500 undergraduate students enrolled, and 5,105 postgraduate students of which 1368 are foreign students from 35 countries.Universiti Kebangsaan Malaysia is one of five research universities in the country. It was ranked number 259th in the world by QS World University Rankings in 2014. It is ranked 98th place in the 100 best new universities established within the last 50 years in the world. It is the only university from Malaysia that made it in the 2012 Quacquarelli Symonds Top 50 Universities Under 50 Years Old list ranked in the 31st place. It placed 53rd and 58th in the QS Top 500 Asian University Rankings in 2011 and 2012 respectively. Wikipedia.

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Aburomman A.A.,National University of Malaysia | Reaz M.B.I.,National University of Malaysia
Proceedings of 2016 IEEE Advanced Information Management, Communicates, Electronic and Automation Control Conference, IMCEC 2016 | Year: 2016

Feature extraction addresses the problem of finding the most compact and informative set of features. To maximize the effectiveness of each single feature extraction algorithm and to develop an efficient intrusion detection system, an ensemble of Linear Discriminant Analysis (LDA) and Principle Component Analysis (PCA) feature extraction algorithms is implemented. This ensemble PCA-LDA method has led to good results and showed a greater proportion of precision in comparison to a single feature extraction method. © 2016 IEEE.

Ibrahim I.A.,National University of Malaysia | Khatib T.,An Najah National University | Mohamed A.,National University of Malaysia
Energy | Year: 2017

This paper presents a size optimization method of the energy sources in a standalone photovoltaic system. The proposed technique implies improved photovoltaic array model, dynamic battery model, and accurate objective function as well as a fast simulation algorithm. The loss of load probability (LLP) is used to define the availability of the system. Different system's configurations with different availability levels are generated using the proposed algorithm. These configurations are evaluated based on system availability and cost. Hourly meteorological and load demand data are utilized in this research. A design example is done to show the application of the proposed method considering the weather profile of Malaysia. The result shows that the optimal sizing ratio of the photovoltaic array (CA) is 1.184, while the sizing ratio for storage battery (CB) is 0.613. In addition, the levelized cost of energy (LCE) for the unit generated of energy by the proposed system is 0.447 $/kWh. © 2017 Elsevier Ltd

Lim J.C.L.,National University of Malaysia | Lee K.E.,National University of Malaysia
Nature Environment and Pollution Technology | Year: 2017

This paper studied the efficiency of another series of advanced oxidation processes involving the use of a chelating ligand, combined with a transition metal forming the transition metal complexes to produce reactive radicals. Previous reports using this H2O2/pyridine/Cu(II) system focused only on the decolorization of a single synthetic dye wastewater. In practice, real dye wastes contain mixture of dyes. Therefore, in this study, we combined two classes of most widely used dyes namely the reactive dye (RD) and disperse dye (DD) in three different ratios of (RD: DD) = (0.25:0.75), (0.50:0.50), and (0.75:0.25) to obtain a better idea of the trend in the treatment efficiency of this system. Experimental results are assessed in terms of percentage chemical oxygen demand (COD) reduction, decolourisation, and the amount of sludge produced. Optimal concentrations were obtained using statistical design of experiment. At optimal concentrations, for (RD:DD) = (0.25:0.75), (0.50:0.50), and (0.75:0.25), the percentage of COD reduction was recorded at 87%, 86% and 81%, respectively, decolourization at 97%, 98% and 96%, respectively while sludge produced was 185 mg/L, 125 mg/L, and 210 mg/L, respectively.

Haque M.Z.,National University of Malaysia | Reza M.I.H.,National University of Malaysia
International Journal of Conservation Science | Year: 2017

The raising of the sea causes salinity intrusion into fresh water zones such as river, lake, floodplain and other lowlands. Salinity intrusion in the Mangrove forest is a continuous process. However, due to the increasing salinity ecological integrity of the Sundarbans have been largely affected. The compositional and functional aspects of flora and fauna have been changing at a great deal. The objective of this study is to delineate the changes of the structure and composition of the Sundarbans Mangrove Forest due to excess salinity intrusion and how salinity affect its biodiversity, wildlife habitat and other ecosystem components. This study reviewed related literature gathered through an extensive survey of various websites and the secondary data obtained from various departments with necessary modifications. The land use maps collected from the Bangladesh Forest Department were interpreted to achieve an elaborate classification of forest type and its gradual change with increasing salinity. Observations at the periphery of Sundarbans explore the effect of salinity on the population, livestock, aquatic species and the paddy fields. We used ArcGIS 9.3 to visualize the salinity prone zones, the boundary of administrative zones and the forest type to identify the causes and intensity of the issues, and to suggest the appropriate mitigating measures. The study states that the salinity intrusion causes the reduction of fresh water availability in Sundarbans. As a result, fresh water loving species are replaced by the species of the saline zone. Most of the areas are found with the small and bushy typed species that reduce biomass in comparison with their standard volume. The study reveals the effects of salinity intrusion in the Sundarbans Mangrove Forest which may affect its compositional, structural and functional integrity. Long-term and short-term policies are recommended to resolve the issues.

Tee Z.K.,National University of Malaysia | Jahim J.M.,National University of Malaysia | Tan J.P.,National University of Malaysia | Kim B.H.,National University of Malaysia
Bioresource Technology | Year: 2017

Calcium carbonate was evaluated as a replacement for the base during the fermentation of glycerol by a highly productive strain of 1,3-propanediol (PDO), viz., Clostridium butyricum JKT37. Due to its high specific growth rate (µmax = 0.53 h−1), 40 g/L of glycerol was completely converted into 19.6 g/L of PDO in merely 7 h of batch fermentation, leaving only acetate and butyrate as the by-products. The accumulation of these volatile fatty acids was circumvented with the addition of calcium carbonate as the pH neutraliser before the fermentation was inoculated. An optimal amount of 15 g/L of calcium carbonate was statistically determined from screening with various glycerol concentrations (20–120 g/L). By substituting potassium hydroxide with calcium carbonate as the pH neutraliser for fermentation in a bioreactor, a similar yield (YPDO/glycerol = 0.6 mol/mol) with a constant pH was achieved at the end of the fermentation. © 2017 Elsevier Ltd

Azim R.,Chittagong University | Islam M.T.,National University of Malaysia
Proceedings of 9th International Conference on Electrical and Computer Engineering, ICECE 2016 | Year: 2016

In this article a microstrip antenna is reported for wideband wireless communication application. The main radiator of this design is printed in the front side of a piece of FR4 dielectric substrate while a finite ground plane is etched on the rear side. To achieve wide operating band, the ground plane is reduced to partial one and defected by inserting slots on its upper edge. It is found that this modification established a proper coupling between ground structure and the radiator, and the investigated antenna attained a measured fractional bandwidth of 130%. Furthermore, the proposed antenna demonstrates omnidirectional radiation characteristics with good gain and efficiency. © 2016 IEEE.

Ubani C.A.,National University of Malaysia | Ubani C.A.,Cahams Research Consultant | Ibrahim M.A.,National University of Malaysia | Teridi M.A.M.,National University of Malaysia
Renewable and Sustainable Energy Reviews | Year: 2017

Emerging development in perovskite sensitized solar cell have ushered in a transformative shift in the evolution of efficient and low-cost solar cell technologies. The improvement represents significant progress in the performance of sensitized solar cells since their breakthrough in 1991. Existing unexplored opportunities with these new developments depicts potential platform to achieve higher efficiency. Earlier development in solid state dye sensitized solar cells (DSSCs) has led to the incorporation of novel semiconductor nanocrystalline quantum dots (QDs) and perovskite as alternative sensitizer to improve device stability and enhance absorption coefficient. The attractiveness of perovskite CH3NH3PbI3 as sensitizer for solar cell incorporates its cost-effectiveness and light-harvesting capability which has shown consistent improvement in device performance in recent years. The incorporation of metal chalcogenides into solid-state dye sensitized solar cells showed significant improvement in power conversion efficiency (PCE) of 18.05%. With CH3NH3PbX3 (X=Cl, Br, or I) as an alternative to dye, device performance has shown to be promising although emerging challenges require a prioritized concern. In this review, recent exciting improvements in the performance of perovskite solar cells were discussed and the fundamental mechanisms incorporated into the structural evolution leading to PCE of 20.8%. In addition, prospects overriding present challenges were proposed for future work toward practical realization of highly-efficient solar cell upon optimization. © 2017 Elsevier Ltd

Othman N.E.,National University of Malaysia | Hassan R.,National University of Malaysia
Journal of Theoretical and Applied Information Technology | Year: 2017

Building on a review of cooperation enforcement in mobile ad hoc networks and tag-based cooperation literature in [1] and the design of mobility-aware tag-based cooperation enforcement approach [2], this article will forward the research by describing the process of building a generic model to test and evaluate the proposed approach for tag-based cooperation in mobile environment. The generic model is an agent-based model. Therefore, this article will begin by introducing agent-based modeling and describing the tools that can be used to develop agent-based models and explains the design of agent-based model for tag-based cooperation in mobile environment. The evaluation of the agent-based model is presented and discussed. © 2005 – ongoing JATIT & LLS.

Zin N.A.M.,National University of Malaysia | Elaklouk A.M.,University of Palestine
International Journal on Advanced Science, Engineering and Information Technology | Year: 2017

The use of serious games in cognitive rehabilitation would be invaluable to the rehabilitation process and provide advantages that may not be available in conventional rehabilitation. Although many recent game-based interventions for cognitive rehabilitation have been reported in the literature, not much knowledge is available on the best approach to developing usable games for individuals with cognitive disabilities. Therefore, Design Science approach was adopted to find a solution to this problem. This paper explores an existing Design Science framework and methodology, which are then combined and reduced into one single framework. This paper further examines how this framework can be used as a means to develop an artefact that can be used as a guideline in developing serious games for cognitive rehabilitation. The Design Science paradigm works well for the development of serious game for cognitive rehabilitation. This paper concludes with a discussion of the research contributions.

Amran M.S.,National University of Malaysia | Rahman S.,National University of Malaysia
Advanced Science Letters | Year: 2017

Fun learning through the use of humour in teaching mathematics can create an effective learning atmosphere. The purpose of this study is to identify students’ perception on the use of humour in teaching mathematics and its relationship with students’ concentration and motivation to learn. The data was collected using a 5 point Likert scale instrument to measure students’ perception and their preferences on the use of humour by their Mathematic teachers. The instrument also measure students’ endorsement on the effect of humour to their concentration and motivation to learn in Mathematics class. The respondents were 278 form four students from secondary schools in Malaysia. The findings were analysed using descriptive statistic. The findings indicate that there is a gap between students’ preferences on the use of humour with teacher’s practice of humour in Mathematic class. The findings also showed that students reported humour does enhance their concentration and learning motivation. The study recommends teachers to create a fun learning environment through the use of humour to motivate students to be engaged in Mathematic class. © 2017 American Scientific Publishers All rights reserved.

Rahman S.,National University of Malaysia | Marzuki M.A.,University of Sfax
Advanced Science Letters | Year: 2017

‘Children not interested to learn,’ ‘easily feel bored of learning’ and ‘having difficulty in understanding complex health knowledge’ are among issues in childhood education. This paper discusses the effect of applying the humanistic learning theory on experiences and learning patterns of children. The strategy of the “child friendly” concept, which is guided by the concept in Carl Rogers’s learning theory, is applied in the children’s learning environment that involves 68 children from ages 3 to 6 years and implemented over a period of 32 weeks in a nursery school. The “child friendly” environment refers to a learning environment, which comprises learning notes and activities with special characteristics that are well liked by and suitable for children as well as providing a learning environment that attracts the interest of children towards learning health issues. The data on children’s experiences and learning patterns were collected from video recordings, observations and anecdotal records throughout the implementation of the program and analysed using ATLAS.ti. The findings showed that the “child friendly” concept strategy that was guided by the humanistic learning theory applied in the children’s learning environment had a positive effect on experiences and learning patterns that ‘elated’ (94.29%), ‘excited’ (90.02%), was ‘accepted’ (98.59%), and ‘appreciated’ (95.71%) by the children. In conclusion, the findings support the “child friendly” concept that was guided by the humanistic learning theory and used in the teaching-learning process of children from ages 3 to 6 years in order to determine experiences and learning patterns such as ‘elation,’ ‘excitement,’ ‘acceptance’ and ‘appreciation.’ This subsequently enhanced children’s motivation to continue learning without feeling bored. © 2017 American Scientific Publishers All rights reserved.

Suparta W.,National University of Malaysia | Mohd Nor W.N.A.W.,National University of Malaysia
Advanced Science Letters | Year: 2017

This paper characterizes GPS total electron content (TEC) during the occurrence of lightning in Antarctic Peninsula during the year 2013. The observation was conducted using ground-based GPS receivers at O’Higgins (OHI3), Rothera (ROTH) and Palmer (PALM). The GPS TEC response was investigated during lightning events. The increment of ΔTEC 0.2 to 0.4 TECU was observed for lightning energy less than 10 million rms during low geomagnetic activity. Meanwhile, an increase of ΔTEC 0.4 to 1.0 TECU is observed for lightning energy more than 10 million rms during unsettled to active storm. It is identified that the response of TEC can be observed ~0.25 hour before the lightning event. Moreover, TEC during equinox and solstice events is shown an increment of 0.7 to 1.9 TECU, which is 38% higher compared with lightning activity. © 2017 American Scientific Publishers All rights reserved.

Yahya M.A.M.,National University of Malaysia | Gan K.B.,National University of Malaysia
Advanced Science Letters | Year: 2017

A Continuous and real time health observing has become an important subject of our life. A simple and feasible Portable devices has done a major role, especially in the biomedical field. We have implemented and developed with an experimental study for two pulsation tubes simultaneously as a fetal and maternal abdominal vessel based on optical continuous detection. A wide range of frequencies from near-infrared to red light wavelength were generated through a phantom. The reflected signals were acquired from one silicon diode and separated by a demodulator through a USB connection to PC by using an NI DAQ 6351 and analysed using LABVIEW software. The settled simulated vascular system contains from a two independent adjustable tube system, demonstrating the fetal and maternal vessel system in different frequencies simultaneously. The two arterial hearts beat pressure with different frequencies is generated utilizing a two different pre-pressure controllable piston pumps with two handmade automatic adjustable relief valve and two flexible tubes to create a complete artificial model of the fetal and maternal vessel system of a dynamic adjustable beat per minute (B.P.M.). The major achieved results are the reflected RED and IR PPG signals from both top and bottom tube simultaneously from one silicon diode. The system that has designed is convenient with any detection systems for a transabdominal optical PPG system tests before produced to the clinics. © 2017 American Scientific Publishers All rights reserved.

Hannan M.A.,University of Tenaga Nasional | Ali J.A.,National University of Malaysia | Mohamed A.,National University of Malaysia | Uddin M.N.,Lakehead University
IEEE Transactions on Industrial Electronics | Year: 2017

This paper presents a random forest (RF) regression based implementation of space vector pulse width modulation (SVPWM) for a two-level inverter to improve the performance of the three-phase induction motor (TIM) drive. The RF scheme offers the advantage of rapid implementation and improved prediction for the SVPWM algorithm to improve the performance of a conventional space vector modulation scheme. In order to show the superiority of the proposed RF technique to other techniques, an adaptive neuro fuzzy inference system (ANFIS) and artificial neural network (ANN) based SVPWM schemes are also used and compared. The proposed speed controller uses a backtracking search algorithm to search for the best values for the proportional-integral controller parameters. The robustness of the RF-based SVPWM is found superior to the ANFIS and ANN controllers in all tested cases in terms of damping capability, settling time, steady-state error, and transient response under different operating conditions. The prototype of the optimal RF-based SVPWM inverter controller of induction motor drive is fabricated and tested. Several experimental results show that there is a good agreement of the speed response and stator current with the simulation results which are verified and validated the performance of the proposed RF-based SVPWM inverter controller. © 2016 IEEE.

Kadhum A.A.H.,National University of Malaysia | Shamma M.N.,National University of Malaysia
Critical Reviews in Food Science and Nutrition | Year: 2017

Lipid is the general name given to fats and oils, which are the basic components of cooking oils, shortening, ghee, margarine, and other edible fats. The chosen term depends on the physical state at ambient temperature; fats are solids and oils are liquids. The chemical properties of the lipids, including degree of saturation, fatty acid chain length, and acylglycerol molecule composition are the basic determinants of physical characteristics such as melting point, cloud point, solid fat content, and thermal behavior. This review will discuss the major lipid modification strategies, hydrogenation, and chemical and enzymatic interesterification, describing the catalysts used mechanisms, kinetics, and impacts on the health-related properties of the final products. Enzymatic interesterification will be emphasized as method that produces a final product with good taste, zero trans fatty acids, and a low number of calories, requires less contact with chemicals, and is cost efficient. © 2017 Taylor & Francis Group, LLC.

Yahoo M.,National University of Malaysia | Othman J.,National University of Malaysia
Science of the Total Environment | Year: 2017

The impact of global warming has received much international attention in recent decades. To meet climate-change mitigation targets, environmental policy instruments have been designed to transform the way goods and services are produced as well as alter consumption patterns. The government of Malaysia is strongly committed to reducing CO2 gas emissions as a proportion of GDP by 40% from 2005 levels by the year 2020. This study evaluates the economy-wide impacts of implementing two different types of CO2 emission abatement policies in Malaysia using market-based (imposing a carbon tax) and command-and-control mechanism (sectoral emission standards). The policy simulations conducted involve the removal of the subsidy on petroleum products by the government. A carbon emission tax in conjunction with the revenue neutrality assumption is seen to be more effective than a command-and-control policy as it provides a double dividend. This is apparent as changes in consumption patterns lead to welfare enhancements while contributing to reductions in CO2 emissions. The simulation results show that the production of renewable energies is stepped up when the imposition of carbon tax and removal of the subsidy is augmented by revenue recycling. This study provides an economy-wide assessment that compares two important tools for assisting environment policy makers evaluate carbon emission abatement initiatives in Malaysia. © 2017 Elsevier B.V.

Ng C.L.,National University of Malaysia | Reaz M.B.I.,National University of Malaysia
Sensors (Switzerland) | Year: 2017

Capacitive biosensors are an emerging technology revolutionizing wearable sensing systems and personal healthcare devices. They are capable of continuously measuring bioelectrical signals from the human body while utilizing textiles as an insulator. Different textile types have their own unique properties that alter skin-electrode capacitance and the performance of capacitive biosensors. This paper aims to identify the best textile insulator to be used with capacitive biosensors by analysing the characteristics of 6 types of common textile materials (cotton, linen, rayon, nylon, polyester, and PVC-textile) while evaluating their impact on the performance of a capacitive biosensor. A textile-insulated capacitive (TEX-C) biosensor was developed and validated on 3 subjects. Experimental results revealed that higher skin-electrode capacitance of a TEX-C biosensor yields a lower noise floor and better signal quality. Natural fabric such as cotton and linen were the two best insulating materials to integrate with a capacitive biosensor. They yielded the lowest noise floor of 2 mV and achieved consistent electromyography (EMG) signals measurements throughout the performance test. © 2017 by the authors. Licensee MDPI, Basel, Switzerland.

Arifin A.,University of Sriwijaya | Sulong A.B.,National University of Malaysia
MATEC Web of Conferences | Year: 2017

Hydroxyapatite is a bioactive material. However, Hydroxyapatite in medical application is limited by its poor mechanical properties. Titanium alloys are biocompatible materials with high specific strength and high corrosion resistance. This combination can successfully be used in biomedical applications. The mixing process is a critical stage in the metal injection molding process because it determines the quality of the metal injection product. The homogeneity of the feedstock depends on the mixing parameters used during the mixing process. An experiment was conducted using Ti6Al4V and hydroxyapatite powder as feedstock at a mixing ratio of 60:40 wt%. This feedstock was mixed with a mixture of polyethylene and palm stearin as the binder. The mixing parameters used in this study were the mixing speed (10 and 30 rpm) and the mixing temperature (130°C and 150°C) at a powder loading of 67%, as determined by the critical powder volume percentage experiment data (69.5%). Increases in the mixing speed and mixing temperature reduced the mixing time to achieve homogeneity. The combined feedstock achieved the highest density at a mixing speed of 30 rpm and a mixing temperature of 150°C. © The Authors, published by EDP Sciences, 2017.

Azim R.,Chittagong University | Islam M.T.,National University of Malaysia
2016 International Conference on Innovations in Science, Engineering and Technology, ICISET 2016 | Year: 2016

The design evolution of planar ultra-wideband slot antennas is presented in this paper. The basic antenna with a Tshaped radiator and ground plane with wide slot is able to exhibit UWB characteristics. Insertion of a curve slit in the front side of the basic antenna helps to generate a stop band at around 3.5GHz while etching of a pair of symmetric slits in the rear side helps to produce a stop band for WLAN. Dual stop band centered at 3.5GHz and 5.5GHz can be obtained by putting both types of slits together. The insertion of slits does not alter the size and shape of basic antenna which gives us an upper hand in the designing of UWB antenna with notch band/s. © 2016 IEEE.

Dey M.,Chittagong University of Engineering and Technology | Dey M.,Premier University | Matin M.A.,Chittagong University of Engineering and Technology | Amin N.,National University of Malaysia
2016 International Conference on Innovations in Science, Engineering and Technology, ICISET 2016 | Year: 2016

The binary semiconductor compound Molybdenum telluride (MoTe2) is For high efficiency and better thermal stability, Molybdenum telluride (MoTe2) is considered as potential solar cell. AMPS (Analysis of Microelectronic and Photonic Structures) simulator is used to investigate the cell performance parameters for ultra-Thin MoTe2 PV cell. In this research work, it has been explored that the cell conversion efficiency of MoTe2 PV cell is improved with the insertion of Zinc Telluride (ZnTe) as back surface field (BSF) above the back contact metal. The highest conversion efficiency of 25.29% was found for ZnTe BSF with only 0.7 μm of absorber layer whereas it was 17.06% for no BSF with 1 μm thickness of absorber layer. The thermal stability of MoTe2 PV cell with ZnTe BSF showed better stability. © 2016 IEEE.

Almasgari A.A.A.S.,National University of Malaysia | Hamzah U.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

A sequence stratigraphic study of the Pliocene age sedimentary rocks was conducted in the central part of Taranaki basin, which is located offshore in the western coast of Taranaki Penisula, New Zealand. The study area is approximately 217.4.km2 consisting of an anticline cut by some faults in the southeastern part of the study area. The purpose of this study was to identify the seismic facies and to determine the seismic sequence stratigraphic boundaries of the Pliocene deposits. Ten seismic sections and three wells were used in this study where many seismic facies were detected such as parallel, sub-parallel, continuous, sub-continuous, wavy, free reflection, chaotic, high amplitude-high frequency and high amplitude-low frequency. Based on reflection terminations and seismic facies two sequence boundaries with their chronostratigraphic units were determined. Sequence boundary 1 (SB1) separates Giant Foresets Formation upper and Giant Foresets Formation middle formations. While sequence boundary 2 separates Giant middle and Giant lower formations. Synthetic seismogram was developed from density and sonic logs and was correlated with the seismic section for locating the sequence boundaries. SB2 is characterized by erosional truncation as shown by the presence of toplaps and downlaps reflection terminations in the central part of the seismic section. A low-amplitude high-frequency reflection was observed above sequence boundary SB1 while high amplitude-low frequency reflection was observed below SB2. © 2016 Author(s).

Piah M.R.M.,National University of Malaysia | Baharum A.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

The use of mengkuang fiber (MK) fibers in NR/HDPE (40/60) blend was studied via surface modification of fiber. The MK fiber was pre-washed with 5%wt/v sodium hydroxide solution prior to treatment with liquid epoxidized natural rubber (LENR). The concentration of LENR were varied from 5%-20%wt in toluene. The effects of LENR concentrations were studied in terms of mechanical properties and morphology formed. Melt-blending was performed using an internal mixer (Haake Rheomix 600). The processing parameters identified were 135°C temperature, 45 rpm rotor speed, 12 minutes processing time and at 20%wt MK fiber loading. The optimum LENR treatment concentration was obtained at 5%wt with tensile strength, tensile modulus, and impact strength of 10.3 MPa, 414.2 MPa and 14.4 kJ/m2 respectively. The tensile modulus of LENR-treated MK fiber filled NR/HDPE bio-composite has shown enhancement up to 16.7% higher than untreated MK fiber. The tensile and impact strength were decreased with increasing LENR concentration due to the broken of MK fibers to smaller particles and adhered to each other. FESEM micrographs confirmed the formation of fiber-fiber agglomeration in NR/HDPE blends. The optical microscope analysis shows MK fibers is shorter than original fiber lengths after NaOH-LENR surface modification. The internal bonding forces of MK fiber seems to be weaker than external force exerted on it, therefore, the MK fiber has broken to smaller particles and reduced the mechanical properties of NR/HDPE/MK(20%) bio-composite. © 2016 Author(s).

Yasin M.H.M.,National University of Malaysia | Ishak A.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

The objective of this study is to investigate the effects of mass suction on double diffusive mixed convection boundary layer flow from a vertical flat plate embedded in a porous medium filled by a nanofluid using Buongiorno's model. The appropriate similarity transformation is used to reduce the partial differential equations into a system of ordinary differential equation, which is then solved numerically using a shooting method. The effects of mass suction parameter on the flow field and heat transfer characteristics are presented and discussed. © 2016 Author(s).

Hasan M.,National University of Malaysia | Ismail S.B.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

The level of phosphorus (P) and the time of application are considered as two of the most important factors affecting crop growth and yield of groundnut (Arachis hypogaea L.). A field experiment was carried out at the greenhouse of the Universiti Kebangsaan Malaysia (UKM), Bangi, Malaysia, in 2014. The objective of the study was to find the best level and the timing of P application, with the aim of getting better growth and higher yield. A complete randomized design with three rates of P (27.5, 55 and 82.5 kg ha-1) were used. The dosage that gave the highest yield and growth was 82.5 kg ha-1 when P application was given at 7, 21, 42 and 60 days after sowing (DAS). The results show that the highest level of P (82.5 kg ha-1) at 7 DAS significantly increased plant height, number of nodules/plant, number of pods per plant, pod yield (kg ha-1), seed weight, oil content and shelling percentage. It can be concluded from the experiment that P fertilizer application at 82.5 kg ha-1 at 7 DAS was necessary for profitable groundnut production in the study area. © 2016 Author(s).

Bahrudin N.F.D.B.,National University of Malaysia | Hamzah U.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

Magnetic data were processed to interpret the geology of Peninsular Malaysia especially in delineating the igneous bodies and structural lineament trends by potential field geophysical method. A total of about 32000 magnetic intensity data were obtained from Earth Magnetic Anomaly Grid (EMAG2) covering an area of East Sumatra to part of South China Sea within 99°E to 105°E Longitude and 1°N to 7°N Latitude. These data were used in several processing stages in generating the total magnetic intensity (TMI), reduce to equator (RTE), total horizontal derivative (THD) and total vertical derivative (TVD). Values of the possible surface and subsurface magnetic sources associated to the geological features of the study area. The magnetic properties are normally corresponding to features like igneous bodies and faults structures. The anomalies obtained were then compared to the geological features of the area. In general, the high magnetic anomalies of the TMI-RTE are closely matched with major igneous intrusion of Peninsular Malaysia such as the Main Range, Eastern Belt and the Mersing-Johor Bahru stretch. More dense lineaments of magnetic structures were observed in the THD and TVD results indicating the presence of more deep and shallow magnetic rich geological features. The positions of Bukit Tinggi, Mersing and Lepar faults are perfectly matched with the magnetic highs while the presence of Lebir and Bok Bak faults are not clearly observed in the magnetic results. The high magnetic values of igneous bodies may have concealed and obscured the magnetic values representing these faults. © 2016 Author(s).

Fadillah M.G.N.,National University of Malaysia | Marlia M.H.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

Following water footprint approach, this study estimates the blue and green water consumption of rice cultivation in 11 states located in Peninsular Malaysia. The latter part evaluates the potential of water deprivation for freshwater resources in Malaysia. Climate data such as rainfall, temperature, humidity, sunshine and wind speed were used to calculate evapotranspiration rate and crop water use. The water footprint for cultivating rice was estimated for both main and off seasons range between 1600 m3/ton to 3300 m3/ton. The result of this study showed that the green water footprint is higher compared to the blue water footprint for both seasons. In conclusion, the potential water deprivation can be determined by integrating the water footprint and water stress index of different watersheds of Malaysia. © 2016 Author(s).

Sasue A.,National University of Malaysia | Kasim Z.M.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

Consumer awareness of the importance of functional foods has greatly grown in the past years. Functional foods with elevated levels of antioxidants are of high demand because of its associated health benefits. As bread is a common component in our daily diet, it may be convenient food to deliver antioxidants at a high concentration. The main approach of this study is to incorporate Kappaphycus alvarezii seaweed powder (SWP) and white flour in the bun formulation in order to develop seaweed bun with higher level of phytochemicals. The fresh Kappaphycus alvarezii seaweeds were washed, soaked in distilled water overnight, dried in a cabinet dryer at 40°C for 24 hours and ground into fine powder using universal miller. There were five different percentages of SWP incorporated into bun that were formulation A - control (0% SWP), B (3% SWP), C (6% SWP), D (9% SWP) and E (12% SWP). All the samples were undergone texture, total phenolic content and DPPH analysis. Seaweed concentration had most significant effect on phytochemical constituents of the bun with TPC (35.07 GAE, mg/100g) and DPPH activity (49.02%) maximized when 12% SWP was incorporated into the flour (P<0.05). The incorporation of the SWP also gives significant effects towards the texture of the bun where the bun becomes harder and denser as compared to the control. © 2016 Author(s).

Sawei J.,National University of Malaysia | Sani N.A.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

Bacillus cereus is a spore-forming, facultative anaerobic, motile microorganism that has been identified as a causative agent of two types of gastrointestinal diseases such as emetic and diarrhea. This foodborne pathogen is found in both vegetative cells and endospores form in foods such as rice either raw or cooked. The aim of this study is to investigate and determine the prevalence, characterize and identify the isolation of vegetative cells and endospores of B. cereus in thirty varieties (n=3) of raw rice from Sabah, Sarawak and Peninsular Malaysia. A total of 90 (n=90) raw rice were examined and 84 (93.33%) samples were positive to vegetative cells of B. cereus. However, only 32 (35.56%) samples were positive for endospore cells that able to germinate after samples were heated at 75°C for 15 mins. The mean log cfu/g for vegetative cells were higher range (0.00 - 4.1533) than visible endospores (0.00 - 3.7533 mean log cfu/g). Sample of raw red rice (UKMRC9) had significantly higher contamination by both vegetative cells and endospores at p<0.05, than the other raw rice samples. © 2016 Author(s).

Zaman A.,National University of Malaysia | Mustapha M.A.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

Watershed delineation is one of the techniques used to identify and analyze spatial characteristics and distribution of an area. Spatial and physical characteristics of each sub basin for example the area of watershed and identification of soil type can contribute to the determination of areas that are vulnerable to flood. Determination of these physical characteristics can be implemented by using Hydrologic Response Unit (HRU) analysis with combination of land-use data, soil and Digital Elevation Model (DEM). The objectives of this study are to delineate Kelantan watershed, and to divide the watershed into sub basins using open source Mapwindow GIS integrated with Soil And Water Analysis Tool (MWSWAT). Data such as DEM, land use and soil data were analyzed. The study identified a total watershed area of 9755.55 km2 (65 percent of Kelantan area), which were divided into 18 sub basins. Applicability of the approach in classifying Kelantan watershed depends on the data and technique. © 2016 Author(s).

Salleh N.S.,National University of Malaysia | Murad A.M.A.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

In this work, the ability of commercial Trichoderma reesei cellulases preparation, Celluclast® or in combination with Accellerase®BG β-glucosidase to hydrolyse pretreated oil palm empty fruit bunch (OPEFB) was evaluated. Celluclast® alone hydrolyzed OPEFB to produce 2.41±0.44 mg glucose per gram OPEFB. However, the production of glucose was significantly improved with supplementation of Accellerase®BG (8.12±0.93 mg/g). This result suggested that the endoglucanases and exoglucanases in Celluclast® and β-glucosidase in Accellerase®BG able to work synergistically to increase the production of glucose from OPEFB. In addition, the production of xylose was also improved by 30% when the enzyme mixture was used. The result suggested that the mixture of Celluclast® with Accellerase®BG work synergistically to improve the production of sugars by removing the inhibition by cellobiose for complete cellulose hydrolysis. The production of glucose and xylose from OPEFB wastes showed the potential of this biomass as the source of renewable energy and fine chemicals production in Malaysia. © 2016 Author(s).

Mohammed N.H.B.,National University of Malaysia | Yaacob W.Z.W.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

The study investigates the characteristic of industrial waste as adsorbents and its potential as heavy metals absorbents in AMD samples. The AMD sample was collected from active mine pond and the pH was measured in situ. The metal contents were analyzed by ICP-MS. The AMD water was very acidic (pH< 3.5), and the average heavy metals content in AMD were high especially in Fe (822.029 mg/l). Fly ash was found to be the most effective absorbent material containing high percentage of CaO (57.24%) and SiO2 (13.88%), followed by ladle furnace slag containing of high amount of CaO (51.52%) and Al2O3 (21.23%), while biomass ash consists of SiO2 (43.07%) and CaO (12.97%). Tank analysis display a huge changes due to pH value change from acidity to nearly neutral phases. After 50 days, fly ash remediation successfully increase the AMD pH values from pH 2.57-7.09, while slag change from acidity to nearly alkaline phase from pH 2.60-7.3 and biomass has change to pH 2.54-6.8. Fly ash has successfully remove Fe, Mn, Cu, and Ni. Meanwhile, slag sample displays as an effective adsorbent to adsorb more Pb and Cd in acid mine drainage. © 2016 Author(s).

Omar A.F.,National University of Malaysia | Ismail I.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

Sesquiterpene synthase (SS) catalyzes the formation of sesquiterpenes from farnesyl diphosphate (FDP) via carbocation intermediates. In this study, the promoter region of sesquiterpene synthase was isolated from Persicaria minor to identify possible cis-acting elements in the promoter. The full-length PmSS promoter of P. minor is 1824-bp sequences. The sequence was analyzed and several putative cis-acting regulatory elements were identified. Three cis-acting regulatory elements were selected for deletion analysis which are cis-acting element involved in wound responsiveness (WUN), cis - acting element involved in defense and stress responsiveness (TC) and cis-acting element involved in ABA responsiveness (ABRE). Series of deletions were conducted to assess the promoter activity producing three truncated fragments promoter; Prom 2 1606-bp, Prom 3 1144- bp, and Prom 4 921-bp. The full-length promoter and its deletion series were cloned into the pBGWFS7 vector which contain β-glucuronidase (GUS) gene and green fluorescent protein (GFP) as the reporter gene. All constructs were successfully transformed into Arabidopsis thaliana based on PCR of positive BASTA resistance plants. © 2016 Author(s).

Kamaruszaman N.,National University of Malaysia | Jamaluddin T.A.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

The unfavourably oriented discontinuities with respect to the slope cutting orientation may results in rock slope failure or instabilities. The main factor that influences the rock slope stability is the geological factors. The role of geology on slope problems and assessment is variable, according to the subsoil constituent and structures itself. Generally, rock masses are contains a plane of weaknesses such as fault, joint, bedding plane, foliation, dyke, folds, etc. Therefore, those structures will drive a rock mass on a slope to break down. Geological processes also play the role in the rock slope stability. These are due to weathering (expose with air and water), surface erosion, seepage occurs along open joints and the chemical reaction in the intact rock with water that produce high porosity (e.g. limestone). To determine the instabilities of rock falls, basic rock mass rating (RMRb) and slope mass rating (SMR) assessment were conducted on rocks slope in Gunung Lang. The study area is divided into three slope zone; GL-1, GL-2 and GL-3. The results indicates that the rock slopes have two possible modes of failure consisting of planar failure and wedge failures. Rock slope GL-1 is relatively in stable condition. Rock slope GL-2 has potential mode of wedge failure. The slope is considered as partially stable and its probability of failure is 40%. Rock slope GL-3 have potential modes of wedge and planar failures. Therefore, the slope is considered as unstable and its probability of failure is 60%. © 2016 Author(s).

Khaidatul Akmar K.,National University of Malaysia | Mahanem M.N.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

Gynura procumbens (GP) is an herbal plant that is used for treating diseases such as diabetes mellitus, cardiovascular and also fertility. The objective of this study was to determine the anti-diabetic and pro-fertility effect of GP on streptozotocin induced male rats within 14 days. A total of 42 male rats were randomly assigned into six groups; normal, negative, and positive control, and three treated groups of different dosages of GP; 150 mg/kg, 300 mg/kg and 450 mg/kg. The treated groups were given aqueous extract GP via oral gavage for 14 consecutive days. The fasting blood glucose (FBG) level in all treated groups showed significant decreased compared to negative and positive group after 14 days treatment. Sperm quality parameters in GP treated group (450 mg/kg) showed significant increase when compared to negative and positive group. It was observed that the histology of testes in the treated group (450 mg/kg) produced a significant result whereby the germinal cell layer shown an arranged order of cells compared to the negative and positive control groups. It appeared that aqueous extract of GP have a pro-fertility effect and possess anti-hyperglycemic activity within 14 days of treatment. © 2016 Author(s).

Purhanudin N.,National University of Malaysia | Awang R.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

We report the structural difference and film properties of amorphous carbon nitride (a-CNx) thin films as a function of PECVD deposition pressure using precursor gases of ethane (C2H6) and nitrogen (N2). The Fourier transform infra-red (FTIR) spectra reveal peaks of single C-N (1100 cm-1), double C=C (1500 cm-1), double C=N (1670 cm-1) and triple C≡N (2340 cm-1). A systematic change in the preferential peaks correspond to the C=N and C≡N triple bonds were found to increase as deposition pressure increased. Field emission scanning electron microscopy (FESEM) provides morphological structure of the film. From the samples prepare at low deposition pressure, the particles tend to agglomerate into clusters with non-homogenous grains distributed over the surface. Higher deposition pressure results in coalescence process of the film, reflecting the formation of grains evenly distributed on the film. The film morphology is increased in voids structure with increase in deposition pressure. Finally, the samples were successfully prepared by PECVD technique with deposition pressure in varied, and the effect of deposition pressure on the chemical bonding and the morphology of the films had been studied. © 2016 Author(s).

Kamil M.S.,National University of Malaysia | Razali A.M.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

Analysis of the wind speed behavior will contribute the vital information for the wind energy potential and its development. Hence, this study focuses on fitting several distributions to determine the most appropriate probability distribution that will describe the wind pattern in Kuala Terengganu and Mersing. Four different statistical distributions have been fitted to the monthly mean wind speed from eight different directions. Two stations of Kuala Terengganu and Mersing have been observed for the period 2000 to 2008. These distributions were tested using Kolmogorov-Smirnov statistic to find the best fit for describing the observed data. The Weibull distribution shows a clear fit for all wind speed directions in both locations. © 2016 Author(s).

Oshah A.,National University of Malaysia | Darus M.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

In this paper, new subclasses of analytic functions in the open unit disk which are defined using generalized integral operator are introduced. Several interesting properties of these classes are obtained, such as inclusion relationships and integral preserving properties are derived. © 2016 Author(s).

Naganthran K.,National University of Malaysia | Nazar R.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

In this study, the stagnation-point flow of a nanofluid towards a stretching/shrinking sheet with heat generation/absorption and convective boundary conditions has been analysed numerically. The governing boundary layer equations in the form of nonlinear partial differential equations are transformed into a system of nonlinear ordinary differential equations by using the similarity transformations, so that they can be solved numerically by the bvp4c function (programme) in Matlab software. The effects of the associated parameters on the numerical results are illustrated in tables and figures. It is found that dual solutions exist in both cases of stretching and shrinking sheet situations. A stability analysis has been conducted to determine the stability of the dual solutions. Results from the stability analysis proved that the first solution is stable and physically realizable whereas the second solution is unstable. © 2016 Author(s).

Shamsuddin R.B.,National University of Malaysia | Karim N.H.A.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

N,N'-bis[4-[1-(2-hidroxyethoxy)]salicylidine]-phenyldiamine-nickel(II) complex has been synthesized by treating N,N'-bis-4-(hydroxysalicylidene)-phenylenediamine-nickel(II) complex with 2-chloroethanol and nickel(II) acetate tetrahydrate in ethanol solvent. The resulting complex formed was characterized using standard spectroscopic and structural techniques which includes 1H, 13C, COSY and HMQC NMR spectroscopy, FTIR spectroscopy and ESI-MS spectrometry. The 1H NMR spectrum displayed all the expected signals with right integration and multiplicity. The formation of Schiff base can be seen at 8.54 ppm for the formation of diimine and the disappearance of aldehyde peak at 9.88 ppm corresponding to the starting material confirms the full conversion. The presence of resonance peak at 3.76 ppm and 4.00 ppm corresponding to the ethyl group of the hydroxyl side chain also confirm the formation of the complex. The FTIR spectrum of the complex confirmed the expected C=N band at 1577 cm-1 and C-H for sp3 stretching band at 2878 cm-1. The formation of the new complex was also confirmed by ESI(+)-MS spectrometry, which showed the molecular peak with adduct ions at [M+K]+=531 a.m.u and [M+Na]+=515 a.m.u. © 2016 Author(s).

Jalani S.A.,National University of Malaysia | Ibrahim N.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

Nipah virus (NiV) is the etiologic agent responsible for the respiratory illness and causes fatal encephalitis in human. NiV L protein subunit is thought to be responsible for the majority of enzymatic activities involved in viral transcription and replication. The L protein which is the viral RNA dependent RNA polymerase has high sequence homology among negative sense RNA viruses. In negative stranded RNA viruses, based on sequence alignment six conserved domain (domain I-IV) have been determined. Each domain is separated on variable regions that suggest the structure to consist concatenated functional domain. To directly address the roles of domains III and VI, site-directed mutations were constructed by the substitution of bases at sequences 2497, 2500, 5528 and 5532. Each mutated L gene can be used in future studies to test the ability for expression on in vitro translation. © 2016 Author(s).

Daud S.N.S.M.,National University of Malaysia | Ghani I.A.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

The pollinating weevil, Elaedobius kamerunicus (EK) has been known to be the most efficient insect pollinator of oil palm, and has successfully improved the oil palm pollination and increased the yield. Its introduction has greatly reduced the need for assisted pollination. The purpose of this study was to identify the population density of oil palm pollinator weevil EK using the concept of pollinator force and to relate the population density with the seasonal effect and the age of oil palm at Lekir Oil Palm Plantation Batu 14, Perak, Peninsular Malaysia. The pollinator force of the weevil was sustained at a range between 3095.2 to 19126.1 weevils per ha. The overall mean of weevil per spikelet shows that the range of weevil was between 13.51 and 54.06 per spikelet. There was no correlation between rainfall and population density of EK. However, positive correlation was obtained between weevil density and the number of anthesising female inflorescence of oil palm (r= 0.938, p< 0.05). Results of t-test show that the 6-year old oil palm stands had significantly different population density than that of a 8-year old oil palm stand. The information of this study should be useful as a baseline data to investigate why there is such a wide range of weevils per ha or spikelet. Further study should also be done to relate the number pollinator force per spikelete and the Fresh fruit Bunch (FFB), fruit set or fruit to bunch ratio. © 2016 Author(s).

Ngah M.S.,National University of Malaysia | Badri K.H.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

A mechanically agitate reactor vessel in a moderate scale size of 500 L has been developed. This vessel was constructed to produce palm-based polyurethane polyol with a capacity of maximum ~400 L. This is to accomodate the demand required for marketing trial run as part of the commercialization intention. The chemistry background of the process design was thoroughly studied. The esterification and condensation in batch process was maintained from the laboratory scale. Only RBD palm kernel oil was used in this study. This paper will describe the engineering design for the reactor vessel development beginning at the stoichiometric equations for the production process to the detail engineering including the equipment selection and fabrication in order to meet the design and objective specifications. © 2016 Author(s).

Mohamed N.,National University of Malaysia | Abdullah A.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

The total phenolic content and antioxidant activity of Kappaphycus alvarezii obtained from Langkawi, Kedah and Semporna, Sabah were evaluated. The total phenolic content (TPC) of the extracts were determined according to the Folin Ciocalteau method and results were expressed as gallic acid equivalents. The antioxidant activities of the extracts were determined by three methods namely Free Radical Scavenging Activity (DPPH), Ferric Reducing Antioxidant Power (FRAP) and Trolox Equivalent Antioxidant Capacity (TEAC). Both of the TPC and FRAP assays showed that seaweed from Semporna, Sabah significantly (p<0.05) had higher antioxidant activities compared to Langkawi, Kedah one (Semporna's seaweed: 73.25 mg GAE/100g and 16.94 μmol TE/100g, Langkawi's seaweed: 54.35 mg GAE/100g and 10.01 μmol TE/100 g). However, the seaweed from Langkawi (60.93 μmol TE/100g) show higher TEAC value compared to seaweed from Semporna (36.36 μmol TE/100g) but for DPPH assay there was no significant difference (p>0.05) between the samples. Pearson coefficient correlation test, showed that there was a positive correlation (p<0.01) between TPC and antioxidant activity (FRAP assay) (r=0.980) and thus it can be concluded that the phenolic compounds was a contributor of the antioxidant activity in Kappaphycus alvarezii. © 2016 Author(s).

Albehbah M.,National University of Malaysia | Darus M.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

We introduce a new subclass of meromorphically analytic functions, which is defined by means of a Hadamard product or convolution. A characterization property such as the coefficient bound is obtained for this class. The other related properties, which are investigated in this paper, include the distortion and the radius of starlikeness. We also consider several applications of our main results to the generalized hypergeometric functions. © 2016 Author(s).

Nurhafizah-Azwa S.,National University of Malaysia | Ahmad K.A.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

A study on benthic macroinvertebrate diversity was conducted at Air Terjun Asahan, Asahan, Melaka. Five stations were selected with distance intervals of approximately 500 metres. Three replicates of benthic macroinvertebrate and water samples were taken. Results classified Air Terjun Asahan in class II, which indicated good water quality based on WQI recommended by the Department of Environment. A total of 1 phylum, 2 classes, 6 order, 30 families, and 2183 individuals were successfully sampled and recorded. The analysis showed that the average value of Shannon Diversity Index, H' (2.19), Pielou Evenness Index, J' (0.30), and Margaleff Richness Index, DMG (3.77) described that Air Terjun Asahan was in moderate condition and the distribution of macroinvertebrates was uniform between stations. Correlation test showed that the WQI had a strong relationship with the diversity indices involved. BMWP, and FBI showed that Air Terjun Asahan was in good water quality. CCA test was conducted to show environmental factors towards benthic macroinvertebrate distribution. The presence of Leptophlebiidae, Baetidae, Heptageniidae and Chironomidae with high abundance of the families showed the potential as biological indicators of a clean ecosystem. © 2016 Author(s).

Aqilahhamuzan H.,National University of Malaysia | Badri K.H.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

Polyurethane (PU) has a unique structure that is dependent on the structure of the starting material used. This research focused on investigating the role of isocyanate groups (NCO) in the determination of the viscoelastic properties of the polymer. Monoester polyol was reacted with three different diisocyanates separately by prepolymerization method. The diisocyanates used were 2,4-diphenyl methane diisocyanate (MDI), toluene 2,4-diisocyanate (TDI) and isophoronediisocyanate (IPDI). Acetone was used as a solvent. IPDI, MDI and TDI were reacted with monoester polyol at ratios of 10:9, 10:10, 10:12 and 10:14 (polyol:diisocyanate). Then, the PU foams produced by the curing process were analyzed by Fourier Transform infrared spectroscopy (FTIR). The FTIR spectra showed the presence of the amide peak (-NH) and the absence of hydroxyl peak (-OH) indicated that the reaction between polyol and diisocyanate has occurred. However, the soxhlet extraction showed that only MDI-based PUs contain crosslinking bond. These cross-linking bond at the ratio of 10:10, 10:12 and 10:14 were 41.3 %,61.1 % and 74.1 % respectively. Thermal properties of the PU foams were determined by differential scanning calorimetry (DSC) and thermogravimetry (TGA) techniques. MDI-based PUs and TDI-based PUs show two values of Tg while IPDI-based PUs only show one Tg value. The tensile strains of PU foams decreased with increasing ratio of isocyanate. Meanwhile, PU foams with ratio of polyol to isocyanate at 10:12 showed the highest tensile stress and modulus compared to at 10:10 and 10:14. © 2016 Author(s).

Rosnaini R.M.,National University of Malaysia | Abdullah A.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

The effect of polishing and cooking on the antioxidant activities of local rice was studied. Brown rice was polished to 2%, 4% and 6% of polishing degree using embryo rice machine to produce three levels of embryo rice. All rice sample (brown rice, embryo rice 1 (2%), embryo rice 2 (4%), embryo rice 3 (6%) and white rice) were cooked using electric rice cooker. The raw and cooked rice samples were analyzed for antioxidant by total phenolic content (TPC), ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays. Polishing degree and cooking treatment showed significant (p≤ 0.05) effects on both antioxidant activities (TPC, FRAP and DPPH radical scavenging values) of the raw and cooked rice samples. Results showed that raw brown rice and raw embryo rice 1 were significantly higher than the other type of rice samples for TPC and FRAP values. In DPPH radical scavenging activities, raw brown rice had the highest value while white rice indicated the otherwise. Cooked brown rice demonstrated significantly higher of FRAP values (p≤ 0.05) than embryo rice 1, followed by embryo rice 2, embryo rice 3 and white rice. No significant differences were observed either between TPC values of cooked brown rice and cooked embryo rice 1 or between the DPPH radical scavenging values of cooked embryo rice 2 and cooked embryo rice 3. High positive correlations were determined between TPC, FRAP and DPPH assays (R2 > 0.70) of the samples. In overall, moderate level of antioxidant activities were detected in the raw and cooked rice samples. © 2016 Author(s).

Selvakumaran N.,National University of Malaysia | Mat Lazim M.A.S.B.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

Malaysia is one of the largest producer of palm oil thus the quantity of biomass each year from this industry is very large. The oil palm frond from palm oil industry can be used as a source of cellulose which can be incorporated into hydrogel to be used as adsorbent. This research reported how to disperse 2 % cellulose in a 'green-solution' prepared by using urea and sodium hydroxide. Polymerization is carried out between the monomers polyacrylamide and cellulose using microwave to form hydrogel. Hydrogel with 2 % cellulose have a swelling index of 1814 %. Meanwhile, zero hydrogel which is made with only polyacrylamide has swelling index of 15 %. Scanning electron microscope shows that cellulose hydrogel have a rough surface compared with zero hydrogel. This might attribute to the high swelling index for cellulose hydrogel compared with zero hydrogel. Meanwhile, FTIR shows that successful polymerization has occurred between polyacrylamide and cellulose with the characteristic band at 1657.99 cm-1 which is for N-H bond. © 2016 Author(s).

Siti-Khaulah A.R.,National University of Malaysia | Noraini T.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

A study on the leaf venation anatomical characteristics was conducted on eight chosen Ficus L. (Moraceae) species in Peninsular Malaysia, namely F. callosa, F. apiocarpa, F. caulocarpa, F. pubigera, F. pendens, F. celebensis, F. mollissima, and F. drupacea. The objective of this study was to observe the significant leaf venation anatomical characteristics that can be used in species classification and identification. Leaf clearing, staining, mounting and observation under a light microscope were techniques used for the study. Veinlets, the ultimate marginal and areolar venation were the main leaf venation anatomical characteristics observed in this study. The presence of complex veinlets in the areolar venation were shown in most species studied (F. callosa, F. pubigera, F. celebensis, F. pendens), whilst simple or uni-veinlets were shown in F. apiocarpa, F. caulocarpa and F. mollissima. Free ending veinlet was absence in F. drupacea. Complete ultimate marginal venation was shown in most species studied, such as in F. callosa, F. caulocarpa, F. pendends, F. mollissima and F. drupacea. Opened areolar venation was observed in most species studied, such as in F. callosa, F. pubigera, F. pendens, F. mollissima, and F. celebensis. Diagnostic leaf venation anatomical characteristic was present in cystolith cells in F. pubigera and trichomes were present on venation in F. mollissima only. As a conclusion, the results of this study have shown that leaf venation anatomical characteristics have taxonomic significance that can be used in differentiation and identification in selected Ficus species studied. © 2016 Author(s).

Khalil A.,National University of Malaysia | Ahmad A.G.B.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

Conditions for an infinite dimensional topological transformation group acting transitively on a smooth open manifold to have a slice at each point were given. The results showed that for a manifold whose dimension is finite and greater than 5, the slice exists at each point of the manifold including points near the infinity, provided that the group is locally compact and the manifold is tame. © 2016 Author(s).

Altameemi R.N.I.,National University of Malaysia | Gopir G.,National University of Malaysia
AIP Conference Proceedings | Year: 2016

In this study we determine the effect of aluminium (Al) and copper (Cu) shielding on the event rate of cosmic ray muons at ground level. The experiment was performed at Bangi in Malaysia with coordinates of 101.78°E, 2.92°N and elevation 30 m above sea level. Measurements were made along the vertical direction using muon telescopes (MTs) of parallel Geiger-Muller (GM) tubes with metal sheets above the MTs of up to 2.4 cm for Al and 2.7 cm for Cu. For these ranges of metal thicknesses, we find that the muon count rates increase linearly with the increase in metal thicknesses. The observed increase rate values are (0.18 ± 0.10) cm-1 and (0.26 ± 0.10)cm-1 for Al and Cu, respectively, with the larger value for Cu as expected from its higher atomic number and density. This indicates that for this thickness range, only the lower region of the Rossi curve is observed, with incoming cosmic ray muons producing charged particles in the metal layers, resulting in shower events or electromagnetic cascade. Thus, for this range of layer thickness, both aluminium and copper are not suitable to be used as shielding materials for ground level cosmic ray muons. © 2016 Author(s).

Hashim H.,University Technology of MARA | Harun Z.,National University of Malaysia
2016 IEEE 8th International Conference on Engineering Education: Enhancing Engineering Education Through Academia-Industry Collaboration, ICEED 2016 | Year: 2016

Semiconductor devices is a fundamental course for electronic engineering students at the Faculty of Electrical Engineering, Universiti Teknologi MARA. Strong semiconductor knowledge helps students in understanding other electronic engineering subjects. The paper aims to analyse students' feedback on the implementation of blended learning in semiconductor devices. The objective of blended learning application is to enhance efficiency of the learning process in semiconductor course. Several activities of blended learning have been implemented in this study in order to obtain students' responses. The survey reveals that a majority of the students agree that the blended learning is suitable to be implemented in the semiconductor devices course. It is hoped that the implementation of blended learning in semiconductor devices can help students increase their interests and confidence level in engineering study. © 2016 IEEE.

Jaddi N.S.,National University of Malaysia | Abdullah S.,National University of Malaysia | Malek M.A.,University of Tenaga Nasional
PLoS ONE | Year: 2017

Artificial neural networks (ANNs) have been employed to solve a broad variety of tasks. The selection of an ANN model with appropriate weights is important in achieving accurate results. This paper presents an optimization strategy for ANN model selection based on the cuckoo search (CS) algorithm, which is rooted in the obligate brood parasitic actions of some cuckoo species. In order to enhance the convergence ability of basic CS, some modifications are proposed. The fraction Pa of the n nests replaced by new nests is a fixed parameter in basic CS. As the selection of Pa is a challenging issue and has a direct effect on exploration and therefore on convergence ability, in this work the Pa is set to a maximum value at initialization to achieve more exploration in early iterations and it is decreased during the search to achieve more exploitation in later iterations until it reaches the minimum value in the final iteration. In addition, a novel master-leader-slave multi-population strategy is used where the slaves employ the best fitness function among all slaves, which is selected by the leader under a certain condition. This fitness function is used for subsequent Lévy flights. In each iteration a copy of the best solution of each slave is migrated to the master and then the best solution is found by the master. The method is tested on benchmark classification and time series prediction problems and the statistical analysis proves the ability of the method. This method is also applied to a real-world water quality prediction problem with promising results. © 2017 Jaddi et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Rafie S.M.M.,National University of Malaysia | Nordin D.,National University of Malaysia
Malaysian Journal of Analytical Sciences | Year: 2017

In this research, hydroxyapatite (HA) nano-size powder was synthesized using wet chemical precipitation technique under atmospheric pressure where calcium hydroxide (Ca(OH)2) and ortho-phosphoric acid (H3PO4) were used as precursors. Distilled water was used as a diluting media for the reaction and sodium hydroxide (NaOH) was used to control the initial pH. The initial pH values, reaction temperature and calcined temperature play an important role in the morphology on HA as well as the phase formation and degree of crystallinity. Nano HA powder has been studied at different initial pH value which is between 9.00 to 11.00, reaction temperature from 80 °C to 100 °C and calcined temperature at 700 °C to 800 °C. The optimum initial pH value was found at pH 10.00, reaction temperature at 100 °C and calcined temperature was at 800 °C. The crystallographic properties were evaluated by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) and Field Emission Scanning Microscope (FESEM). The Design Expert version 9.0.2 with statistical and graphical analysis of the result, by using analysis of variance (ANOVA) was applied to optimize variable in the process of synthesis of HA. Based on analysis of variance (ANOVA) that has been perform, calcined temperature was to be influential variables on mass of HA with value of probability less than 0.05. © 2017, Malaysian Society of Analytical Sciences. All rights reserved.

This work used blending and casting method to synthesis sodium alginate/sulfonated-GO (SA/SGO) polymer electrolyte membrane for direct methanol fuel cell (DMFC). The composition of sulfonated-GO in the membrane is varied from 0 wt% to 1 wt%. The functional groups in the membrane were confirmed by Fourier Transform Infrared analysis. The water uptake capacity of the membrane as observed was reduced with addition of sulfonated-GO as filler in the membrane. Thus, the proposed membrane has good potential to be an alternative membrane in DMFC application. © 2017, Malaysian Society of Analytical Sciences. All rights reserved.

Manjunatha J.G.,Mangalore University | Deraman M.,National University of Malaysia
Analytical and Bioanalytical Electrochemistry | Year: 2017

Sodium dodecyl sulfate surfactant modified graphene paste electrode (SDSMGPE), prepared by electrochemical immobilization of the Sodium dodecyl sulfate surfactant (SDS) on a graphene paste electrode, was applied for simultaneous determination of dopamine (DA) in the existence of ascorbic acid (AA) and uric acid (UA) through cyclic voltammetry(CV) and differential voltammetry(DPV). The modified electrode shows strong electrocatalytic function for the oxidation of DA, AA and UA and three well-defined voltammetric peaks of about 167 mV, 12 mV and 303 mV by CV method. A linear response in the range of (1×10-5)-(1×10-3) M with a detection limit of 4.7×10-6M and limit of quantification limit 15×10-6M for DA was obtained. This SDSMGPE indicated a potent and persistent electron mediating behavior bring up by adequately separated oxidation peaks of DA, AA and UA. The bare graphene paste electrode (BGPE) and SDSMGPE were characterized using Energy-dispersive X-ray spectroscopy (EDX) and Field emission scanning electron microscopy (FESEM) were used to check the electrochemical efficiency of electrodes. The effects of graphene paste constitution, concentration, surfactant, pH, and scan rate were investigated. The modified electrode is highly stable and can be used to the determination of DA in injection samples. The proposed method is simple, fast, sensitive, selective, stable, reproducible and accurate. © 2017 by CEE (Center of Excellence in Electrochemistry).

A screen-printed copper ion sensor with photocurable poly(n-butyl acrylate) (pBA) membrane based on ionophore o-xylylene bis(N,N-diisobutyldithiocarbamate) (o-xc) was successfully fabricated. Poly(2-hydroxylethyl methacrylate) (pHEMA)-modified Ag/AgCl screen-printed electrode was used in the development of the sensor and the sensor was characterized by potentiometric method. Optimization of pBA membrane for the electrode was carried out by varying the compositions of sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaTFPB) and o-xc to determine the best analytical performance. The addition of NaTFPB and the increment of its ratio relative to o-xc showed super-Nernstian, small linear range, and high detection limit. For sensor fabricated based on o-xc without the addition of NaTFPB, the sensor showed Nernstian response. The best optimized sensor showed Nernstian slope with 31.29 mV/decade over a wide linear range of 1.0 × 10-2 – 1.0 × 10-6 M and low detection limit of 1.89 × 10-7 M. The sensitivity of this sensor was also improved over the other copper ion sensors fabricated by similar photocuring technique. In addition, based on the separate solution method (SSM), this sensor exhibited good selectivity towards copper ion with low logarithm selectivity coefficient value for monovalent and divalent cations namely K+, Na+, Ca2+, Mg2+, Ni2+ and Co2+. © 2017, Malaysian Society of Analytical Sciences. All rights reserved.

Rajalingam S.,Putrajaya Hospital | Sakthiswary R.,National University of Malaysia | Hussein H.,Putrajaya Hospital
Archives of Rheumatology | Year: 2017

Objectives: This study aims to determine the predictors of poor sleep quality in rheumatoid arthritis (RA). Patients and methods: This was a monocentric, cross sectional, case-control study which was conducted at the Putrajaya Hospital, Malaysia. We recruited 46 patients with RA (3 males; 43 females; mean age 48.15±14.96) and 46 age and sex-matched healthy controls (3 males; 43 females; mean age 47.11±12.22). RA patients were assessed for their disease activity based on disease activity score in 28 joints, disease damage based on radiographic erosions, and functional status based on Health Assessment Questionnaire Disability Index. The Pittsburgh Sleep Quality Index (PSQI) scores were determined by interviewing all the subjects. Subjects with RA were further subdivided based on their PSQI scores as “good sleepers” with PSQI scores of <5 and “poor sleepers” with PSQI scores of ≥5. Results: The percentage of poor sleepers was significantly higher among RA patients (47.83% vs 9.57%). Median scores of 5 out of 7 components of the PSQI were higher among RA patients compared to controls. Among poor sleepers with RA, a significantly higher proportion tested positive for anti-citrullinated cyclic peptide autoantibodies (p=0.037). Besides, poor sleepers had significantly higher median Health Assessment Questionnaire Disability Index (p=0.017) than good sleepers. However, both Health Assessment Questionnaire Disability Index (p=0.968) and anti-citrullinated cyclic peptide (p=0.431) were insignificant when entered in the equation of a logistic regression model. Conclusion: The findings of this study demonstrate a link between functional disability, anti-citrullinated cyclic peptide antibodies, and sleep quality in RA. © 2017 Turkish League Against Rheumatism. All rights reserved.

Mansor M.S.,University of Malaya | Mansor M.S.,National University of Malaysia | Ramli R.,University of Malaya
PLoS ONE | Year: 2017

Tropical rainforests are considered as hotspots for bird diversity, yet little is known about the system that upholds the coexistence of species. Differences in body size that are associated with foraging strategies and spatial distribution are believed to promote the coexistence of closely related species by reducing competition. However, the fact that many babbler species do not differ significantly in their morphology has challenged this view. We studied the foraging ecology of nine sympatric babbler species (i.e., Pellorneum capistratum, P. bicolor, P. malaccense, Malacopteron cinereum, M. magnum, Stachyris nigriceps, S. nigricollis, S. maculata, and Cyanoderma erythropterum) in the Krau Wildlife Reserve in Peninsular Malaysia. We investigated; i) how these babblers forage in the wild and use vegetation to obtain food, and ii) how these trophically similar species differ in spatial distribution and foraging tactics. Results indicated that most babblers foraged predominantly on aerial leaf litter and used gleaning manoeuvre in intermediate-density foliage but exhibited wide ranges of vertical strata usage, thus reducing interspecific competition. The principal component analysis indicated that two components, i.e., foraging height and substrate are important as mechanisms to allow the coexistence of sympatric babblers. The present findings revealed that these bird species have unique foraging niches that are distinct from each other, and this may apply to other insectivorous birds inhabiting tropical forests. This suggests that niche separation does occur among coexisting birds, thus following Gause' law of competitive exclusion, which states two species occupying the same niche will not stably coexist. © 2017 Mansor, Ramli. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Abdullah H.,National University of Malaysia | Ramli R.,National University of Malaysia | Wahab D.A.,National University of Malaysia
International Journal of Advanced Manufacturing Technology | Year: 2017

Reducing machining time in a milling process is one of the important criteria to improve the overall efficiency of the machining process. This paper presents a study on the reduction of machining time, focusing on contour parallel machining to increase the efficiency and performance during the machining process. One method to enhance the performance of contour parallel machining is by defining a tool path interval that is larger than the radius of the cutting tool in a roughing operation because of its capability of reducing the tool path length and machining time. However, this causes the occurrence of an uncut region at the corner and at the centre of a contour parallel. This uncut region can be removed through an additional tool path known as the clear tool path. Therefore, in this paper, a new method based on an optimisation technique is introduced to generate a clear tool path that removes the entire uncut region in contour parallel machining at minimum cutting time. Ant colony algorithm (ACO) is used to optimise the clear tool path length in contour parallel machining time by minimising the movement of cutting tool in removing the entire uncut regions. A new transition rule has been established from the conventional ACO, which adapted the uncut region occurring at the corner of the contour parallel. Then, to validate the optimisation result, a cutting experiment was carried out using computer numerical control (CNC) milling machine. It can be ascertained from this study that the optimisation of the clear tool path gives optimal tool path length whilst reducing the cutting time in the roughing process. © 2017 Springer-Verlag London

Yusoff M.A.,National University of Malaysia | Sarjoon A.,University of Peradeniya
Religions | Year: 2017

This paper aims to examine the overall impact of anti-halal and anti-slaughtering campaigns in the context of post-war Sri Lanka. The reemergence of majoritarian ethno-religious anti-minority nationalist forces and their intensified anti-minority hatred and violence have made it challenging for ethno-religious minorities in Sri Lanka to engage in religious norms and duties. This is especially true for the Muslim community. Numerous Islamic fundamentals have been criticized and opposed. Muslims have had to endure threats and acts of violence. These campaigns and violent oppositions, imposed by the Buddhist-nationalist forces, have caused concern for Muslims performing their obligatory religious duties and norms. In Sri Lanka, the Muslim community has been allowed to produce halal food and slaughter animals for human consumption and religious rituals for a long period without disturbance. Unfortunately, retaliation and hatred in the post-civil war era in the country have threatened these rights. Thus, it has become imperative to investigate the motivating factors of the anti-halal and anti-animal slaughtering campaigns and violence, as well as their related impact, which is lacking in the existing literature on ethno-religious politics in the context of Sri Lanka. This study found that the anti-halal and anti-animal slaughtering campaigns and oppositions that have been intensified by the Buddhist nationalist forces were part of anti-Muslim sentiments intended to sabotage the economic pride of Muslims and undermine their religious renaissance. The study also found that these campaigns have been facilitated by the state and that continuous facilitation of the anti-Muslim sentiments and campaigns, including the anti-halal and anti-animal slaughter campaigns, would challenge the country’s economic prosperity and the rebuilding of ethno-religious harmony. © 2017 by the authors. Licensee MDPI, Basel, Switzerland.

Al-Hamadani A.K.O.,National University of Malaysia | Alsaqour R.A.,National University of Malaysia
ARPN Journal of Engineering and Applied Sciences | Year: 2017

Mobile Ad Hoc Networks (MANETs) is a collection of wireless mobile nodes forming a temporary network without using any established infrastructure or centralized administration. Generally, with high mobility environment and high load network traffic, network performance may be degraded causing packet loss or increase overhead. Of the Dynamic Source Routing (DSR) protocol for the MANETs. Average throughput, average end-to-end delay, and routing overhead, by increasing the time and number of the node. In this paper, we study the performance of DSR average throughput, average end-to-end delay, and routing overhead. Simulator (NS) version 2.35 used to study the performance of in both DSR-TCP and DSR-UDP. The simulation result shows that when the time is increased affected the average throughput, average end-to-end delay, and routing overhead, and routing overhead, and when to increase the number of nodes by increasing the average throughput, average end-to-end delay, and routing overhead, by decreasing path. © 2006-2017 Asian Research Publishing Network (ARPN). All rights reserved.

Alani H.,National University of Malaysia | Alsaqour R.,National University of Malaysia
ARPN Journal of Engineering and Applied Sciences | Year: 2017

Mobile Ad-hoc Network (MANET) is an important technology that is widely used in many applications. Routing discovery and route maintenance are important issues in MANET. Broadcasting is used in a MANET to discover a route in on-demand routing protocols. Establishment and regular maintenance of a route represent the challenges issue. Therefore, nodes require to broadcast control packets among themselves. This situation leads to broadcast storm problem, which increases overhead of control packets and decreases the performance of the network. In this paper, the Ad-hoc On-demand Distance Victor (AODV) routing protocol is used for implementing the propose scheme, namely AODV-Packet Timing Information (PTI), to reduce the unnecessary control packets for discovery routing. In addition, the proposed AODV-PTI scheme reduced the network overhead. Network Simulation version 2.35 (NS2.35) was used to compare the proposed scheme with AODV routing protocol in terms end-to-end delay, average throughput, packet delivery ratio, and packet overhead ratio. © 2006-2017 Asian Research Publishing Network (ARPN). All rights reserved.

Sheremet M.A.,Tomsk Polytechnic University | Pop I.,Babes - Bolyai University | Ishak A.,National University of Malaysia
International Journal of Heat and Mass Transfer | Year: 2017

Natural convection of micropolar fluid in a right-angled wavy triangular cavity has been analyzed numerically. Governing equations formulated in dimensionless stream function, vorticity and temperature using the Boussinesq and Eringen approaches with appropriate initial and boundary conditions have been solved by finite difference method of the second-order accuracy. The effects of the dimensionless time, Prandtl number, vortex viscosity parameter, and undulation number on streamlines, isotherms, vorticity isolines as well as average Nusselt number at wavy wall and fluid flow rate inside the cavity have been studied. Obtained results have revealed essential heat transfer reduction and fluid flow attenuation with vortex viscosity parameter. © 2016 Elsevier Ltd

Mohd-Tahir N.-A.,University of Newcastle | Mohd-Tahir N.-A.,National University of Malaysia | Li S.-C.,University of Newcastle
Osteoporosis International | Year: 2017

Summary: This review analyzes the economic costs of HF in Asia. The availability and quality of studies on the burden of osteoporosis in Asia are very scarce. There is a need to encourage more quality cost of osteoporosis studies based on standardized methods to convince healthcare authorities in implementing appropriate strategies. Introduction: Osteoporosis fractures, especially hip fractures, impose large economic costs to governments and societies. This review aimed to systematically analyze available evidence on healthcare costs associated with osteoporosis-related hip fractures (HF) in Asia. Methods: Articles were systematically sought from databases including PubMed, EMBASE, and EBSCOHost between 2000 and 2015. Total costs associated with HF care, the cost components, and length of stays were retrieved and analyzed. Study designs were also qualitatively analyzed. Results: The availability of published studies on economic burden of HF in Asia is severely lacking with only 15 articles met the inclusion criteria. Even among the included studies, only two studies reported comprehensive costs evaluating all costs including indirect or intangible costs. Most studies satisfactorily reported criteria for conducting economic evaluation, but large variations existed in the methodological design. Due to study design and other influencing factors, large variation in the cost of HF treatment from US$774 to US$14,198.90 (median S$2943), representing an average of 18.95% (range: 3.58–57.05%) of the countries’ 2014 GDP/capita, was observed. This highlighted the heavy burden of managing HF in Asia with about 40% of the included studies reported using more than one third of GDP/capita. Conclusion: There is a paucity of burden of illness studies of osteoporosis in the Asian region. For the few available studies, there was a lack of standardization in methodological approach in evaluating the economic burden of the disease. There is a need to encourage more quality burden of illness studies of osteoporosis to inform policymakers in healthcare planning. © 2017 International Osteoporosis Foundation and National Osteoporosis Foundation

Nordin R.,National University of Malaysia | Ismail M.,National University of Malaysia
APCC 2012 - 18th Asia-Pacific Conference on Communications: "Green and Smart Communications for IT Innovation" | Year: 2012

There are two known MIMO transmission scheme in the wireless link-level research: Space-Time Coding (STC) and Spatial Multiplexing (SM). STC aims to achieve maximum antenna diversity and improve wireless link reliability, while SM, on the other hand provides a capability for increasing the data rate by higher spectral efficiencies, i.e. more bits/s/Hz of bandwidth. Most MIMO simulations consider ideal transmission spatial subchannels condition, whereby the fading correlation between each spatial subchannel is uncorrected with uniform Rayleigh's distribution. However, in a more realistic propagation environment, spatial correlation does exist between antenna pairs and affects the MIMO transmission link, resulting in reduced capacity and loss of Bits Error Rate (BER). The main aim of this paper is to investigate the effect of spatial interference due to spatially correlated MIMO subchannels by employing a dynamic subcarrier allocation, based on the Orthogonal Frequency Division Multiple Access (OFDMA) transmission scheme. Focus is given in the downlink path, since the Mobile Station (MS) is expected to benefit from the rich multiuser diversity gain given from the dynamic subcarrier allocation. From the simulation results, the BER performance between both the STC and SM scheme will be analyzed to further understand the limitation in transmission under different spatial correlation. © 2012 IEEE.

BACKGROUND: Hepatocellular carcinoma (HCC) is a common cancer that is frequently diagnosed at an advanced stage. Transarterial chemoembolisation (TACE) is an effective palliative treatment for patients who are not eligible for curative treatment. The two main methods for performing TACE are conventional (c-TACE) or with drug eluting beads (DEB-TACE). We sought to compare survival rates and tumour response between patients undergoing c-TACE and DEB-TACE at our centre.MATERIALS AND METHODS: A retrospective cohort study of patients undergoing either treatment was carried out from January 2009 to December 2014. Tumour response to the procedures was evaluated according to the modified Response Evaluation Criteria in Solid Tumors (mRECIST). Kaplan-Meier analysis was used to assess and compare the overall survival in the two groups.RESULTS: A total of 79 patients were analysed (34 had c-TACE, 45 had DEB-TACE) with a median follow-up of 11.8 months. A total of 20 patients in the c-TACE group (80%) and 12 patients in the DEB-TACE group (44%) died during the follow up period. The median survival durations in the c-TACE and DEB-TACE groups were 4.9 ± 3.2 months and 8.3 ± 2.0 months respectively (p=0.008). There was no statistically significant difference noted among the two groups with respect to mRECIST criteria.CONCLUSIONS: DEB-TACE demonstrated a significant improvement in overall survival rates for patients with unresectable HCC when compared to c-TACE. It is a safe and promising approach and should potentially be considered as a standard of care in the management of unresectable HCC.

Suparta W.,National University of Malaysia
2011 IEEE International Conference on Space Science and Communication: "Towards Exploring the Equatorial Phenomena", IconSpace 2011 - Proceedings | Year: 2011

Upper-lower atmospheric coupling due to its transport energy that occurs throughout the Sun-Earth system is fundamental science to space physics, aerospace and satellite communication, meteorology and terrestrial climate cycle. Upper-lower atmospheric coupling studies can explain some physical mechanisms of how solar activity influences terrestrial weather/climate changes. To clarify this coupling, the analysis of propagation delays in GPS-transmitted signals in the upper and lower atmosphere during transient events associated with intense geomagnetic storms is conducted within the Antarctic polar cap. From the correlation between the ionospheric total electron content (TEC) and tropospheric precipitable water vapor (PWV) variations, the global electric circuit (GEC) is identified as a possible physical mechanism for the coupling process. © 2011 IEEE.

Suparta W.,National University of Malaysia | Adnan J.,National University of Malaysia | Ali Mohd.A.Mohd.,National University of Malaysia
2011 IEEE International Conference on Space Science and Communication: "Towards Exploring the Equatorial Phenomena", IconSpace 2011 - Proceedings | Year: 2011

Knowledge of lightning activity in the middle atmosphere down to Earth surface and its relationship with a global warming phenomenon is posing a great challenge for observational and prediction studies. This paper utilized the GPS data to monitor the tropospheric precipitable water vapor (PWV) changes as a climate variable due to lightning discharges. Analysis data on November 2009 over Bangi area within the radius of 20 km showed that all the lightning activities were preceded by Intra-Cloud (IC) and followed by Cloud-to-Ground (CG) after a certain time gap. For most cases in this region found that the lightning activity was frequent in the afternoon between 13:00 and 20:00 local time (LT) and the CG was accompanied by IC in all the time but not vice versa. Based on the 14 samples of lightning days, there were 64.29% and 28.57% correlated with an increase and decrease in PWV content, respectively. The finding can be motivating the further research on utilizing the GPS data as a guide to predict the occurrence of lightning. © 2011 IEEE.

Jusoh R.,Universiti Malaysia Pahang | Nazar R.,National University of Malaysia | Pop I.,Babes - Bolyai University
International Journal of Mechanical Sciences | Year: 2017

The flow and heat transfer of magnetohydrodynamic three-dimensional Maxwell nanofluid over a permeable stretching/shrinking surface with convective boundary conditions is numerically investigated. The partial differential equations governing the flow and heat transfer are transformed to a set of ordinary differential equations by using the suitable transformations for the velocity, temperature and concentration components. These equations have been solved numerically by employing the bvp4c function in Matlab. Numerical solutions are obtained for the skin friction coefficient and the local Nusselt number. Dual solutions are discovered and hence the stability analysis has been done to identify which solution is stable and physically realizable and which is not stable. Solutions are obtained for the skin friction coefficients and local Nusselt number for several values of the parameters, namely the suction parameter, Deborah number, Biot number and Prandtl number. The solutions are presented in some graphs and tables and are analyzed and discussed in detail. © 2017 Elsevier Ltd

Baharuddin N.A.,National University of Malaysia | Muchtar A.,National University of Malaysia | Somalu M.R.,National University of Malaysia
Materials Letters | Year: 2017

SrFe0.5Ti0.5O3−δ perovskite-structured ceramic was produced using wet processing method namely glycine-nitrate combustion technique. The quality of powders produced through this wet processing method was strongly related to processing parameters and heat treatment. This study investigated the effect of calcination temperature and mixing time of nitrate solution on the formation of SrFe0.5Ti0.5O3−δ. Results revealed that calcination temperature and mixing time significantly affected the purity and average crystallite size of SrFe0.5Ti0.5O3−δ. The crystallite grew to 31.48 nm when the calcination temperature was increased, whereas small crystallites (∼30 nm) were produced when the mixing time was prolonged. In terms of the purity of powders, XRD analysis indicated that secondary phases (Sr3Fe2O7 and TiO2) were retained when the calcination temperature was further increased to 1300 °C. As the mixing time was prolonged, secondary phases were removed. After 15 h of mixing, the lowest intensity of secondary peak was observed. The effects of mixing time on the production of pure and fine crystallites of SrFe0.5Ti0.5O3−δ powders were more significant than those of calcination temperature. Thus, mixing time should be prolonged until the optimum duration is reached to produce pure SrFe0.5Ti0.5O3−δ perovskite-structured ceramic powders. © 2017 Elsevier B.V.

Alirr O.I.,National University of Malaysia | Rahni A.A.A.,National University of Malaysia
IECBES 2016 - IEEE-EMBS Conference on Biomedical Engineering and Sciences | Year: 2016

This paper presents the development of automatic segmentation of the inferior vena cava (IVC) in the proximity of the liver in abdominal CT scans. In our proposed framework, starting from an initial contour mask the active contour method is used to delineate the IVC by propagating an elliptical contour in each image slice sequentially in the CT scans. The framework consists of three main steps: general vessel enhancement and segmentation, initial contour delineation and localized active contour propagation. The framework was tested on the publically available IRCAD data set. The results are promising and show good overlap with the IRCAD IVC ground truth data set. © 2016 IEEE.

Chong K.S.,National University of Malaysia | Gan K.B.,National University of Malaysia
IECBES 2016 - IEEE-EMBS Conference on Biomedical Engineering and Sciences | Year: 2016

Thermal ramping rate is the key parameters to determine the performance of portable PCR. In this work, a portable PCR system was developed with two different dimensions of Aluminium block. The dimensions of the blocks were 30 mm × 30 mm × 8 mm (portable-8) and 30 mm × 30 mm × 15 mm (portable-15). The thermal ramping rate of the block was evaluated by heating up and cooling down the block between 50°C to 95°C. Commercial portable PCR systems like OpenPCR, Slim PCR cycler and miniPCR™ were used as a benchmark to determine the thermal ramping rate of the developed system. The results show the portable-8 had better thermal ramping rate performance and shorter heating period. © 2016 IEEE.

Ahmad W.N.W.,National University of Malaysia | Ali N.M.,National University of Malaysia
2016 3rd International Conference on Computer and Information Sciences, ICCOINS 2016 - Proceedings | Year: 2016

The rapid growth of information technology and communication has make the development of persuasive technology become aggressive. Trust has become one of the crucial elements in persuasive technology apart of credibility. This paper investigated trust in terms of cognitive and affective perception in relationship of human-computer interaction with persuasive technologies particularly in fitness application and educational games on environmental sustainability. A study was conducted with 25 participants for 6 weeks which requires them to use both categories of persuasive technologies. The result shows that the lack of trust problem in using persuasive technology found to be strongly significant. Cognitive trust perception is the main perception that leads users in making trust decision compared to affective trust. © 2016 IEEE.

Tan K.W.M.,National University of Malaysia | Lee Y.K.,National University of Malaysia
Journal of Biotechnology | Year: 2017

Biofuel production from genetically-engineered microalgae is currently among the most widely studied strategies in generating renewable energy. However, microalgae currently suffer from low oil yields which limit the commercial feasibility of industrial-scale production. A major bottleneck in cost-efficient biofuel production from microalgae is the dilemma between biomass productivity and lipid accumulation. When grown under stressful culture conditions such as nitrogen depletion, microalgae accumulate large amounts of neutral lipids, but it comes at the expense of growth which negatively impacts overall lipid productivity. Overexpression of acyl-ACP thioesterases (TE) had been successful in increasing the production of fatty acids (FA) in prokaryotes such as E. coli and cyanobacteria, but has not been effectively tested in microalgae. In this study, we introduced a TE from D. tertiolecta (DtTE) into C. reinhardtii to investigate its effects on FA production without compromising growth. The results indicate that C. reinhardtii transformants were able to produce 63 and 94% more neutral lipids than the wild-type, which translates to an approximately 56% improvement in total lipids, without compromising growth. These findings demonstrate the cross-species functionality of TE, and provide a platform for further studies into using TE as a strategy to increase biofuel production from microalgae. © 2017 Elsevier B.V.

Choong S.-M.,National University of Malaysia | El-Shafie A.,University of Kuala Lumpur | Wan Mohtar W.H.M.,National University of Malaysia
Water Resources Management | Year: 2017

In this study, the Artificial Bee Colony (ABC) algorithm was developed to solve the Chenderoh Reservoir operation optimisation problem which located in the state of Perak, Malaysia. The proposed algorithm aimed to minimise the water deficit in the operating system and examine its performance impact based on monthly and weekly data input. Due to its capability to identify different possible events occurring in the reservoir, the ABC algorithm provides promising and comparable solutions for optimum release curves. The optimal release curves were then used to stimulate the reservoir release under different operating times under different inflow scenarios. To investigate the performance of both the monthly and weekly ABC optimisation employed in the reservoir, the well-known reliability, resilience and vulnerability indices were used for performance assessment. The indices tests revealed that weekly ABC optimisation outperformed in terms of reliability and vulnerability leading to the development of a better release policy for optimal operation. © 2017, Springer Science+Business Media Dordrecht.

Kamarudin N.,Malaysian Nuclear Agency | Wan Abdullah W.S.,Malaysian Nuclear Agency | Abdul Hamid M.A.,National University of Malaysia
Materials Science Forum | Year: 2017

This paper presents the luminescence properties of dysprosium (Dy) doped calcium sulfate (CaSO4) phosphor material produced by co-precipitation technique with 0.1-0.5 mol% concentration of dopant. The crystallinity of the produced powder was studied using x-ray powder diffraction (XRD). The XRD spectrum shows high purity anhydrite CaSO4 phosphor material produced. The average crystallite size of 74 nm with orthorhombic crystal system was obtained. The luminescence behavior of produced CaSO4: Dy was studied using a photoluminescence (PL) spectrometer. The excitation and emission spectrum peaks associated with defects and vacancies of the phosphor material at claimed crystalline phase. The mixed peaks of excitation and emission that corresponds to micro and nano sized particle was shown for the produced powders. These properties show that the produced powders have wide range of luminescence detection with many electron traps ready for thermoluminescence (TL) information storage. © 2017 Trans Tech Publications, Switzerland.

Hamzah N.,University Technology of MARA | Abd Samad W.Z.,International Islamic University Malaysia | Yarmo M.A.,National University of Malaysia
Materials Science Forum | Year: 2017

Selective catalytic hydrogenolysis of glycerol on Os/bentonite catalyst represents a low cost and green route for 1,2-propanediol which is major community chemical used in the production of antifreeze functional fluids, paints and humectants. The experimental results combined with the characterization studies using TPR, FESEM-EDX and XPS techniques revealed that the optimum calcination temperature was 300 °C with glycerol conversion obtained was 80.7%. This might be due to the presence of Os metal species as an active site with binding energy(BE) of Os 4f at 51.2 eV in XPS analysis. TPR profile also shows two obvious peak at reduction temperature of 95 °C and 140 °C represent for Os3+ and Os4+ species respectively. The presence of Os3+ and Os4+ species were also confirmed by XPS analysis. © 2017 Trans Tech Publications, Switzerland.

Thongtha A.,Naresuan University | Chan H.-Y.,National University of Malaysia | Luangjok P.,Naresuan University
Key Engineering Materials | Year: 2017

This study investigated the application of phase change material and fins into photovoltaic panel. The experimental design was divided into 2 cases: conventional photovoltaic and photovoltaic with phase change material and fins. The thermal performance and electrical efficiency was tested under the solar radiation simulator between 500 and 1000 W/m2. The insolation intensity was tested by an incident-light photometer. The power of the nine halogen lamps was controlled by a simple voltage control device. It was found that temperature of normal PV module is constant after the tested time of 20 minutes. The temperatures of PV module with phase change material and fins were lower than a normal PV module throughout the testing duration. Approximately 2-6% of photovoltaic module temperatures have decreased and this have improved the electrical efficiency of about 1-4%. This indicated the use of phase change material and fins is able to decrease the photovoltaic module temperature and thus increase the efficiency of photovoltaic module cooling. © 2017 Trans Tech Publications.

Khatun R.,National University of Malaysia | Reza M.I.H.,National University of Malaysia | Moniruzzaman M.,National University of Malaysia | Yaakob Z.,National University of Malaysia
Renewable and Sustainable Energy Reviews | Year: 2017

Cruel oil or green gold is a dilemma for the oil palm industry. The oil palm industry (planting and milling) has a devastating impact on the environment and ecosystems. Oil palm plantations and expansion cause deforestation, habitat loss, forest fragmentation, biodiversity loss, food chain disruption, soil property changes, water and air pollution, conversion of wetlands and arable lands, and increased greenhouse gas (GHG) emissions, resulting in annual fires as well as increasing both subsidence and flood risk. Palm oil mill effluents (POME) are toxic compounds that cause eutrophication and acidification, pollute terrestrial and aquatic systems and release greenhouse gases. However, the oil palm industry is a million-dollar industry that ensures food security (oil and fat). There is increasing demand for palm oil due to population growth and for use as a biofuel feedstock. Significant higher production per hectare in comparison to other oil crops is the main advantage of oil palm. The anthropogenic pressure on the environment is increasing to fulfil the demand and increasing susceptibility to natural disasters. Therefore, the sustainability of this industry is an urgent need. This critical review identified gaps and researched ways for the oil palm industry to be sustainable. Maintaining ecological integrity (ecological health, connectivity, resilience); justifying land allocation (ecosystem service mapping); providing awareness, good management practices, no/minimum production gaps, high yield and disease resistant cultivar generation and plantations, supplemental forms of alternative sources, zero-waste milling technology; and locating plantations on suitable land without further deforestation can fulfil the oil palm industry's present and future demands without impairing the ecosystem or environment. © 2017 Elsevier Ltd

Abdullah M.,National University of Malaysia | Kamarudin S.K.,National University of Malaysia
Renewable and Sustainable Energy Reviews | Year: 2017

Titanium dioxide nanotubes (TNTs) have attracted a considerable amount of attention over the past several decades. TNTs in the form of high-quality nanotube bundled structures may enhance the performance of several applications and may be suitable in various field; fuel cells, photocatalytic systems, energy storage devices, sensors and environmental analysis systems. The unique properties of TNTs make it able to be use in those field with minimum problems encountered. The fabrication of TNTs was discussed briefly with its advantages and disadvantages stated. Thus, this study investigates the use of TNTs in several promising applications and describes the current problems together with future potential developments in related fields. © 2017 Elsevier Ltd

Baqir M.A.,National University of Malaysia | Choudhury P.K.,National University of Malaysia
Journal of Electromagnetic Waves and Applications | Year: 2017

The existence of broadband slow-waves through slab waveguide comprised of sub-wavelength-sized bulk gold and bounded with graphene and silica layers was investigated. A monolayer of graphene medium was taken to be interposed between the gold core and the silica cladding (of the guide). The dispersion behavior exhibits that the guide supports only the fundamental transverse magnetic (TM0) mode, whereas the transverse electric (TE) and the higher order TM modes are blocked. Furthermore, slow-waves can sustain in the guide in the entire visible region of the electromagnetic spectrum. © 2017 Informa UK Limited, trading as Taylor & Francis Group

Baharum A.,National University of Malaysia | Kamil Othman N.,National University of Malaysia | Samsu Z.,Malaysian Nuclear Agency
Materials Science Forum | Year: 2017

In this study, three different alloys Stainless Steel 316 (SS316), Titanium 6Al-4V (Ti6Al4V) and Hastelloy 276 (H276) were exposed to the wet environment with 12% of water vapor and Ar-20%O2 for 10 h at 900 ºC. The oxidation behavior of the samples was analyzed using weight change measurement technique and optical microscope (OM). The phases of the oxide layer on corroded sample were determined using X-ray diffraction (XRD). The difference in the weight gain indicating the difference in the rate of the oxide growth for the samples. Sample Ti6A-l4V showed the most aggressive oxidation behavior compared to the other samples. OM analysis showed a multilayer oxide scale formed on the Ti6A-l4V and H276 samples but only single layer of oxide forms on SS316. Oxide scale for the samples were analyzed using XRD, the result showed the formation of chromia (Cr2O3) on SS316. Titanium oxide (TiO2) and alumina oxide (Al2O3) were detected on Ti6Al4V, while H276 showed the formation of nickel manganese oxide (Ni7.2Mn0.2O8) and nichromite (NiCr2O4). © 2017 Trans Tech Publications, Switzerland.

Hussein S.A.,National University of Malaysia | Dahnil D.P.,National University of Malaysia
International Journal of Applied Engineering Research | Year: 2017

The AODV has evolved into many variants over the past ten years. The routing protocols have been improved from selecting minimum number hop counts to consider more factors affecting path selections. The transmission power increases with increased distance between each node. Hence, a higher amount of energy is consumed while transmitting than receiving data. Many traditional routing protocols consider nodes’ energy consumption and several energy-related parameters, such as energy consumed per packet, remaining battery power, and energy required per transmission. This paper introduces a new technique for improving path selection by combining ant-colony optimization and lion optimization algorithm after all possible paths are discovered in the network. This technique improves the energy efficiency and the performance metrics of each node. © Research India Publications.

Lee L.C.,National University of Malaysia | Liong C.-Y.,National University of Malaysia | Jemain A.A.,National University of Malaysia
Chemometrics and Intelligent Laboratory Systems | Year: 2017

ATR-FTIR spectroscopy in the combination with chemometrics has been practiced over the past decades. Works presented in numerous disciplines provide ample empirical evidence in support for the coupling relationship. However, Data Pre-processing (DP) which constitutes the first step in chemometric analysis pipelines, is seldom given reasonable attentions. The aim of this paper is two-fold: (a) to review contemporary DP practice strategy by ATR-FTIR user, and (b) to critically discuss the rationales that could have been nurturing such practices. In the first part, basic concepts of chemometrics and ATR-FTIR spectroscopy are described. Then, the status quo of DP practice strategy is outlined and critically discussed on whether the contemporary practice has been malpractice or best practice. Finally, rationales that could have possibly contributed to some of the malpractices are discussed. © 2017 Elsevier B.V.

Toll D.G.,Durham University | Rahman Z.A.,National University of Malaysia
Geotechnique | Year: 2017

This paper presents the results of a set of 22 triaxial tests on an unsaturated artificially cemented sand. The results are used to explore the applicability of a number of unsaturated soil frameworks for interpreting the shear strength. Constant water content triaxial tests were carried out on unsaturated specimens, using the axis translation technique to measure suctions during shearing. The test results on the unsaturated material were referenced against a series of drained and undrained triaxial tests that were carried out on saturated specimens. The results of the unsaturated testswere analysed to investigate the effect of the suction and degree of saturation on the shear strength at the critical state. The results show that the critical state stress ratio in terms of net stress (Ma) was found to be larger than the saturated critical state stress ratio (Ms). It was also found that the stress ratio in terms of suction (Mb) reduced as suction increased (when the degree of saturation reduced below 30%). Interestingly, during the initial desaturation phase when the degree of saturation reduces considerably, the stress ratio Mb was largely unaffected by desaturation. It was only when the suction increased sufficiently that the microvoids within the cementing material could start to desaturate that a reduction in Mb was seen. This occurred at suctions in excess of the residual suction when the global degree of saturation was changing very little. This implies that the suction is contributing to the strength of the cementing material itself. © 2017, ICE Publishing. All rights reserved.

Ali A.A.,National University of Malaysia | Saad S.,National University of Malaysia
2016 3rd International Conference on Information Retrieval and Knowledge Management, CAMP 2016 - Conference Proceedings | Year: 2016

A machine readable dictionary (MRD) is an electronic dictionary that enables query processing. One of the common processing tasks that has been widely applied is Concept Hierarchy Induction which aims at identifying concepts with its corresponding taxonomies. The existing concept hierarchy approaches for Islamic domain are using limited linguistic patterns. This study aims to propose an unsupervised concept hierarchy induction for the Islamic domain by extending the patterns and rules. In fact, Term Frequency-Inverse Document Frequency (TF-IDF) was carried out in order to identify the most frequently used concepts. Furthermore, two syntactical features were used including POS tagging and chunk parser in order to identify the tagging for each word (e.g. verb, noun, adjective, etc.) and extracting Noun Phrases (NP). Hence, the proposed extension patterns aim at utilize lexico-syntactic patterns to induce the concept hierarchy. That demonstrates the usefulness of extending patterns for the Islamic domain. © 2016 IEEE.

Ooi T.C.,National University of Malaysia | Chan K.M.,National University of Malaysia | Sharif R.,National University of Malaysia
Nutrition and Cancer | Year: 2017

Cancer is one of the major causes of death worldwide, and the incidence and mortality rates of cancer are expected to rise tremendously in the near future. Despite a better understanding of cancer biology and advancement in cancer management, current strategies in cancer treatment remain costly and ineffective. Hence, instead of putting more efforts to search for new cancer cures, attention has now been shifted to the development of cancer chemopreventive agents as a preventive measure for cancer formation. It is well known that neoplastic transformation of cells is multifactorial, and the occurrence of oxidative stress, chronic inflammation, and genomic instability events has been implicated in the carcinogenesis of cells. Zinc l-carnosine (ZnC), which is clinically used as gastric ulcer treatment in Japan, has been suggested to have the potential in preventing cancer development. Multiple studies have revealed that ZnC possesses potent antioxidant, anti-inflammatory, and genomic stability enhancement effects. Thus, this review provides some mechanistic insight into the antioxidant, anti-inflammatory, and genomic stability enhancement effects of ZnC in relevance to its chemopreventive potential. © 2017 Taylor & Francis Group, LLC.

Chow Y.-P.,National University of Malaysia | Alias H.,National University of Malaysia | Jamal R.,National University of Malaysia
BMC Cancer | Year: 2017

Background: Relapsed pediatric B-acute lymphoblastic leukemia (B-ALL) remains as the leading cause of cancer death among children. Other than stem cell transplantation and intensified chemotherapy, no other improved treatment strategies have been approved clinically. Gene expression profiling represents a powerful approach to identify potential biomarkers and new therapeutic targets for various diseases including leukemias. However, inadequate sample size in many individual experiments has failed to provide adequate study power to yield translatable findings. With the hope of getting new insights into the biological mechanisms underpinning relapsed ALL and identifying more promising biomarkers or therapeutic targets, we conducted a meta-analysis of gene expression studies involving ALL from 3 separate studies. Method: By using the keywords "acute lymphoblastic leukemia", and "microarray", a total of 280 and 275 microarray datasets were found listed in Gene Expression Omnibus database GEO and ArrayExpress database respectively. Further manual inspection found that only three studies (GSE18497, GSE28460, GSE3910) were focused on gene expression profiling of paired diagnosis-relapsed pediatric B-ALL. These three datasets which comprised of a total of 108 matched diagnosis-relapsed pediatric B-ALL samples were then included for this meta-analysis using RankProd approach. Results: Our analysis identified a total of 1795 upregulated probes which corresponded to 1527 genes (pfp < 0.01; FC > 1), and 1493 downregulated probes which corresponded to 1214 genes (pfp < 0.01; FC < 1) respectively. S100A8 appeared as the top most overexpressed gene (pfp < 0.01, FC = 1.8) and is a potential target for further validation. Based on gene ontology biological process annotation, the upregulated genes were most enriched in cell cycle processes (enrichment score = 15.3), whilst the downregulated genes were clustered in transcription regulation (enrichment score = 12.6). Elevated expression of cell cycle regulators (e.g kinesins, AURKA, CDKs) was the key genetic defect implicated in relapsed ALL, and serve as attractive targets for therapeutic intervention. Conclusion: We identified S100A8 as the most overexpressed gene, and the cell cycle pathway as the most promising biomarker and therapeutic target for relapsed childhood B-ALL. The validity of the results warrants further investigation. © 2017 The Author(s).

News Article | April 28, 2017
Site: www.theguardian.com

Tamim Chalati remembers an Aleppo where you could get pizza at 3am. “I had a good salary and social life,” the scientist says, recalling how he used to take his two children out for “hot and crispy barbecue food”, their favourite, several times a week. They lived a comfortable life, with his wife a doctor, and he head of the Department of Pharmaceutics and Pharmaceutical Technology at the University of Aleppo. When war broke out in 2011, first only cracks appeared in Chalati’s world – the electricity would go off, they’d be without water for a few days. But on one summer day in 2012, they found the streets empty and the hospital closed. “We then saw many people walking west [away from a battle in the eastern part of the city], and they told us the war had reached us.” That night there were air strikes, and the family watched in horror as the security situation spiralled out of control, food became scarce and the value of money plummeted. Only 10 students out of 100 were now attending his classes, and when by the end of the year many colleagues had left the country, Chalati and his wife debated if they should too. But they held out until January 2013, when two blasts at the University of Aleppo killed 80 people. Chalati was in his office. His mind went immediately to his children, who were in school, just a few kilometres from the blast. “I couldn’t reach [them] to find out if they were still alive – it was really terrible,” he says. They were safe, but one of the explosions destroyed the kiosk where he often picked up coffee on the school run. The academic began frantically applying for positions at universities in Turkey, Jordan and the UAE – any posting that could give his family a route out of Syria. There would be another two tense years before he finally secured a fellowship through the Institute of International Education’s (IIE) Scholar Rescue Fund. Today the Chalitis are living in England and he is a research associate in the chemistry department at the University of York. Chalati is one of the lucky ones. The IIE, which has helped rescue persecuted scholars since 1919, currently has an acceptance rate of less than 20% for qualified Syrian scholars. It is not the only organisation offering support to academics in danger, but “the needs still far outstrip the resources available,” says James King, assistant director of the Scholar Rescue Fund. The organisation estimates that among the millions who fled Syria there are 2,000 university professionals. Many are still stuck in makeshift camps, and even if resettled, are unable to work. They fly under the radar as academics are not considered one of the most at-risk refugee groups. Yet more than 450 have been assassinated in Iraq since 2003, and an analysis by Scholars at Risk of 158 reported attacks against university professionals in 35 countries from May 2015 to September 2016 found threats ranged from travel restrictions to wrongful prosecutions, forced disappearances and murder. “Scholars, scientists and human rights activists are targeted from every direction,” says Radwan Ziadeh, a senior analyst at the Arab Centre in Washington DC. He should know – the former dentist left Syria in 2007 after receiving threats from the Assad’s security forces after calling for government reform, and he’s currently on an Isis kill list. His asylum case in the US has been pending for three years. So why don’t host countries do more to make the most of these scientists, medics, engineers and other skilled workers? “The main obstacle is the lack of political will, with the rise of the populist movements around the world,” Ziadeh says, explaining that politicians too often treat refugees as a homogenous group. King thinks that a lack of awareness about their educational qualifications, as well as practical challenges related to cost, language barriers, and qualifications assessment, are issues. “Governments and higher education institutions are beginning to recognise the opportunity here,” he says. “But we have a real responsibility to ensure that refugee scientists are supported to continue their academic work because these are the very individuals who will be rebuilding their countries, who will build healthy diaspora communities, and who will really contribute to their host communities.” Chalati experienced the issue of getting his qualifications recognised first-hand. He has a master’s and PhD from a French university but his BA in pharmacy is from a Syrian university, so in the UK he cannot be employed permanently at a school of pharmacy, unless he redoes some exams – a process that could take three years. “In Syria I was a senior academic, but when I came to the UK I had to start from scratch as a postdoc, as if the previous five years of my career did not exist,” he says. Still, scientific institutions can play an important role in helping refugee scientists integrate into their new communities. “Our scholars often don’t consider themselves refugees: when they are integrated into a lab they’re scientists again, and it’s very important for them to be able to move beyond this reductionist label of refugee,” King says. In March, a workshop was convened by The World Academy of Sciences (TWAS) to discuss how to better support refugee scientists. They recommended that scientific communities establish relations with refugee processing centres, and that host governments accelerate the approval of asylum applications from scientists. TWAS also discussed how to rebuild scientific communities in countries returning to stability, suggesting governments provide tax exemptions and laboratory facilities to persuade skilled workers to return. Eqbal Mohammed Dauqan, a Yemeni scientist now on a scholarship at the National University of Malaysia, is sceptical about these recommendations. In March 2015, she was head of the medical laboratory sciences department at Al-Saeed University of Taiz, but had spent eight months without the internet, electricity or salary, and a bomb hit her house. “When students and researchers finish their fellowships how are they coming back here?” she says. “We don’t even have an airport, and even if they [get here] they are not going to have a stipend for research, because what remains of the government has no money.” Personally, she is not sure of what her next move should be – her scholarship will run out in 2018. “Now I am not a refugee scientist, I am a visiting scholar, but maybe I’ll be a refugee next year.” Join our community of development professionals and humanitarians. Follow @GuardianGDP on Twitter.

Shari M. Ling, MD has been selected to receive the first-ever Public Service Award from NKF, established to honor those who have dedicated their careers to public service and who have helped to shape public policies or government programs that improve outcomes for kidney patients.  Dr. Ling currently serves as the Deputy Chief Medical Officer for the Centers for Medicare and Medicaid Services (CMS) and Medical Officer in the Center for Clinical Standards and Quality (CCSQ).  In her role at CMS, she assists the CMS Chief Medical Officer in the agency's pursuit of better health care, healthier populations and smarter spending. Dr. Ling's committed focus is on the achievement of meaningful health outcomes for patients and families through the delivery of high quality, person-centered care, across all care settings. Her clinical focus and scientific interest is in the care of persons with dementia, multiple chronic conditions and functional limitations. Derek Forfang, a kidney patient and long-time kidney disease advocate, has been selected to receive the first-ever Celeste Castillo Lee Patient Engagement Award, established in honor of Celeste Castillo Lee, a longtime advocate for patient-centered care and empowerment. It is the highest honor given by NKF to a distinguished kidney patient who exemplifies NKF's mission and Celeste's legacy of putting patients at the center of all aspects of healthcare through their involvement with NKF and community partners.  Mr. Forfang, of San Pablo, California, has been an end-stage renal disease (ESRD) patient since 1999.  He received a kidney transplant and has also been on peritoneal dialysis and hemodialysis.  A regional leader of NKF's Kidney Advocacy Committee and a member of the Public Policy Committee, Derek has worked tirelessly to protect and improve care for the kidney community. Merck been selected to receive the 2017 Corporate Innovator Award which recognizes industry partners that advance the field of nephrology by addressing an unmet medical need, or improving upon an existing practice, therapeutic or technology.  Merck's innovative new treatment for hepatitis C, ZEPATIER, is the only direct anti-viral agent specifically tested and approved for use in patients with chronic kidney disease stages four and five. Paul Palevsky, MD has been selected to receive the Dr. J. Michael Lazarus Distinguished Award established to honor Dr. Lazarus for his major contributions to the clinical science and care of dialysis patients, and to recognize individuals whose research has yielded novel insights related to renal replacement therapy.  Dr. Palevsky is Professor of Medicine and Clinical and Translational Science in the Renal-Electrolyte Division at the University of Pittsburgh School of Medicine; and serves as Chief of the Renal Section at the VA Pittsburgh Healthcare System.  Dr. Palevsky's research has primarily focused on acute kidney injury and critical care nephrology. He will be presenting the Lazarus lecture on "We Don't Have to Fail at Acute Renal Failure: A Multidisciplinary Approach to Quality Improvement" on Friday, April 21st at 8:45 a.m. at the NKF Spring Clinical Meetings. Susanne Nicholas, MD, MPH, PhD has been selected to receive the Medical Advisory Board Distinguished Service Award established to recognize an individual for their educational activities and community service in promoting the mission of NKF on a local level.  Dr. Nicholas is a tenured Associate Professor of Medicine at UCLA in the Division of Nephrology where she maintains her clinical responsibilities, and the Division of Endocrinology, Diabetes and Hypertension, where she conducts research.  She is also a Clinical Hypertension Specialist.   Dr. Nicholas' research interests include understanding and identifying key factors that promote the pathogenesis of diabetic kidney disease (DKD); uncovering and validating novel biomarkers that may predict DKD progression; and quantifying renal structural changes associated with DKD in response to novel therapeutics, using stereology principles. Her research over the past 15 years has led to the identification of a novel biomarker of DKD, which is currently being validated in clinical studies. Katherine R. Tuttle, MD, FASN, FACP, FNKF, has been selected to receive the prestigious Garabed Eknoyan Award, created to recognize an individual who has promoted the mission of NKF in Making Lives Better for people with kidney disease through the exceptional contributions to key initiatives of NKF such as the Kidney Disease Outcomes Quality Initiative (KDOQI) or clinical research in the field of kidney disease.  Dr. Tuttle is the Executive Director for Research at Providence Health Care in Spokane, and serves as Co-Principal Investigator of the Institute of Translational Health Sciences, Investigator at Kidney Research Institute, and Clinical Professor of Medicine for the University of Washington.  Dr. Tuttle's major research interests include diabetic kidney disease, hypertension, renal vascular disease, nutrition in chronic kidney disease, and transitional care.  She has chaired numerous workgroups focused on diabetes and kidney disease including NKF's KDOQI Workgroup for Diabetes and Chronic Kidney Disease. Jonathan Himmelfarb, MD has been selected to receive the Donald W. Seldin Award, established to recognize excellence in clinical nephrology in the tradition of one of the foremost teachers and researchers in the field, Dr. Donald W. Seldin.  Dr. Himmelfarb is a Professor of Medicine, Director of the Kidney Research Institute, and holds the Joseph W. Eschbach, M.D. Endowed Chair in Kidney Research at the University of Washington School of Medicine.   He is the author of more than 200 peer-reviewed publications, has served on numerous grant review committees and scientific advisory boards and has held leadership positions in many national and international nephrology societies.  Dr. Himmelfarb has served on expert panels for the U.S. Food and Drug Administration, Veterans Health Administration, and Centers for Medicare & Medicaid Services. He is also a nephrologist who cares for patients with kidney disease, and an internationally recognized educator about kidney disease. Raymond R. Townsend, MD has been selected to receive the Shaul G. Massry Distinguished Lecture Award, established to honor Dr. Massry for his scientific achievements and contribution to the kidney health care community and to NKF.  Dr. Townsend is Professor of Medicine and an Associate Director of the Center for Human Phenomic Studies at the University of Pennsylvania.  He is currently a Principal Investigator evaluating the role of demographic, phenotypic, humoral and genetic factors in the progression of kidney disease and the development and progression of cardiovascular disease in patients with chronic kidney disease.  He was also the Principal Investigator of a multicenter effort evaluating the specific role of pulse wave velocity in the renal and cardiovascular consequences of chronic kidney disease.   Dr. Townsend led the work group that wrote the KDOQI Commentary on the 2012 KDIGO Guideline on this subject, and most recently co-chaired the NKF workshop on Potassium Homeostasis in Disease and Health, the report on which will soon be published in the American Journal of Kidney Disease and Journal of the American Society of Hypertension. Tilakavati Karupaiah, PhD, APD, AN has been selected to receive the Joel D. Kopple Award, an annual award honoring an individual who has made significant contributions to the field of renal nutrition.  Dr. Karupaiah is an Accredited Practicing Dietitian with Dietitian's Association of Australia, a Professor and Head of the Dietetics Program at the National University of Malaysia; and also Adjunct Associate Professor at Wayne State University, Detroit.    Dr. Karupaiah's involvement in renal nutrition began because of a lack of dietitians in this field in Malaysia, and dialysis patients needed patient-friendly information about local diets. At the National University of Malaysia, she encouraged early exposure of dietetic students to renal patient care through community engagement, outpatient counseling and practical skills on patient diet planning. Dr. Karupaiah is now targeting capacity building mentorship for developing renal dietitians in Malaysia through nutrition research. For the past 26 years, nephrology healthcare professionals from across the country have come to NKF's Spring Clinical Meetings to learn about the newest developments related to all aspects of nephrology practice, network with colleagues, and present their research findings. The NKF Spring Clinical Meetings are designed for meaningful change in the multidisciplinary healthcare teams' skills, performance, and patient health outcomes.  It is the only conference of its kind that focuses on translating science into practice for the entire healthcare team. 1 in 3 American adults is at risk for kidney disease.  26 million American adults have kidney disease—and most aren't aware of it.  Risk factors for kidney disease include diabetes, high blood pressure, family history, and age 60+.  People of African American; Hispanic; Native American; Asian; or Pacific Islander descent are at increased risk for developing the disease.  African Americans are 3 ½ times more likely, and Hispanics 1 ½ times more likely, to experience kidney failure. The National Kidney Foundation (NKF) is the largest, most comprehensive and longstanding organization dedicated to the awareness, prevention and treatment of kidney disease.  For more information about NKF visit www.kidney.org. :  Full press releases on each award recipient, including quotes for attribution, are hyperlinked by recipient's name and can also be found in the Newsroom at www.kidney.org. To view the original version on PR Newswire, visit:http://www.prnewswire.com/news-releases/national-kidney-foundation-honors-leading-researchers-clinicians-patient-advocates-and-more-at-its-26th-annual-spring-clinical-meetings-300442333.html

Berhanuddin D.D.,University of Surrey | Berhanuddin D.D.,National University of Malaysia | Lourenco M.A.,University of Surrey | Gwilliam R.M.,University of Surrey | Homewood K.P.,University of Surrey
Advanced Functional Materials | Year: 2012

The optically active carbon related G-center is attracting great interest because of evidence that it can provide lasing in silicon. Here a technique to form the G-center in silicon is reported. The carbon G-center is generated by implantation of carbon followed by proton irradiation. Photoluminescence measurements confirm the controlled formation of high levels of the G-center that, importantly, completely dominates the emission spectrum. Unlike previous methods of introducing the G-center the current approach significantly is truly fully compatible with standard silicon ULSI (ultralarge scale integration) technology. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hasan M.,University of Adelaide | Reaz M.,National University of Malaysia
Measurement Science Review | Year: 2012

The aim of this paper is to model the algorithm for Fetal ECG (FECG) extraction from composite abdominal ECG (AECG) using VHDL (Very High Speed Integrated Circuit Hardware Description Language) for FPGA (Field Programmable Gate Array) implementation. Artificial Neural Network that provides efficient and effective ways of separating FECG signal from composite AECG signal has been designed. The proposed method gives an accuracy of 93.7% for R-peak detection in FHR monitoring. The designed VHDL model is synthesized and fitted into Altera's Stratix II EP2S15F484C3 using the Quartus II version 8.0 Web Edition for FPGA implementation.

Thamburaja P.,National University of Malaysia | Liu J.,National University of Singapore
International Journal of Solids and Structures | Year: 2014

Although large-volume metallic glasses (MGs) are susceptible to shear localization due to their intrinsically strain-softening response, recent experiments and molecular dynamics simulations have shown that small-volume MGs samples are able to exhibit work hardening response. Here, we seek to address two issues regarding the mechanical response of small-volume MGs at low homologous temperatures from a continuum-based modeling perspective: (1) are MGs capable of exhibiting a work hardening response, and (2) what is the physical mechanism which causes its work hardening response? Along with implementing a recently-developed finite-deformation, strain gradient plasticity-based constitutive model for MGs into a self-developed finite-element code, we study the tensile response of small-volume MG samples of various sizes through finite-element simulations. Our simulations show that small-volume MG samples are capable of exhibiting a work hardening response provided the following conditions are met: (a) the sample size is small enough, and (b) the appropriate microscopic boundary conditions for the free volume are imposed on the sample. © 2014 Elsevier Ltd. All rights reserved.

Mohmad A.R.,University of Sheffield | Mohmad A.R.,National University of Malaysia | Bastiman F.,University of Sheffield | Sweeney S.J.,University of Surrey | David J.P.R.,University of Sheffield
Applied Physics Letters | Year: 2011

Photoluminescence (PL) of GaAs0.97 Bi0.03 alloy was measured over a wide range of temperatures and excitation powers. Room temperature PL with peak wavelength of 1038 nm and full-width-half-maximum of 75 meV was observed which is relatively low for this composition. The improved quality is believed due to reduced alloy fluctuations by growing at relatively high temperature. The temperature dependence of PL peak energy indicated significant exciton localization at low temperatures. Furthermore, the band gap temperature dependence was found to be weaker than GaAs. An analysis of dominant carrier recombination mechanism(s) was also carried out indicating that radiative recombination is dominant at low temperature. © 2011 American Institute of Physics.

Pudukudy M.,National University of Malaysia | Pudukudy M.,Sree Neelakanta Government Sanskrit College | Yaakob Z.,National University of Malaysia | Mohammad M.,National University of Malaysia | And 2 more authors.
Renewable and Sustainable Energy Reviews | Year: 2014

Renewable alternative energy sources are getting more attention due to the depleting nature of non-renewable fossil fuels. Increasing global warming, caused by the combustion of fossil fuels, triggered the intense research in finding out better energy options with low emission. Among the potential energy options, hydrogen is a clean fuel candidate as it simply produces water as byproducts when burning. Hydrogen can be generated from different renewable sources and Asia is one of the continents which is rich in renewable energy resources. The resources, safety parameters, public acceptability, and proper government incentives are the major factors affecting the implementation of hydrogen as an economical energy source in Asian countries. The present review deals with the necessity of employing hydrogen as an alternative fuel, its production paths, storage issues, transportation and the available sources. Special emphasis has been given to the discussion of renewable hydrogen economy in some Asian countries like, Japan, Korea, China, India and Malaysia. The challenges in the execution of hydrogen as an economical fuel in Asia are also highlighted. © 2013 Elsevier Ltd.

Hatamlou A.,Islamic Azad University at Khoy | Hatamlou A.,National University of Malaysia | Abdullah S.,National University of Malaysia | Nezamabadi-Pour H.,Shahid Bahonar University of Kerman
Swarm and Evolutionary Computation | Year: 2012

Clustering is an attractive and important task in data mining that is used in many applications. Clustering refers to grouping together data objects so that objects within a cluster are similar to one another, while objects in different clusters are dissimilar. K-means is a simple and efficient algorithm that is widely used for data clustering. However, its performance depends on the initial state of centroids and may trap in local optima. The gravitational search algorithm (GSA) is one effective method for searching problem space to find a near optimal solution. In this paper, we present a hybrid data clustering algorithm based on GSA and k-means (GSA-KM), which uses the advantages of both algorithms. The GSA-KM algorithm helps the k-means algorithm to escape from local optima and also increases the convergence speed of the GSA algorithm. We compared the performance of GSA-KM with other well-known algorithms, including k-means, genetic algorithm (GA), simulated annealing (SA), ant colony optimization (ACO), honey bee mating optimization (HBMO), particle swarm optimization (PSO) and gravitational search algorithm (GSA). Five real and standard datasets from the UCI repository have been used to demonstrate the results of the algorithms. The experimental results are encouraging in terms of the quality of the solutions and the convergence speed of the proposed algorithm. © 2012 Elsevier B.V. All rights reserved.

Rafiza S.,Institute for Medical Research | Rampal K.G.,National University of Malaysia | Tahir A.,Institute for Public Health
BMC Infectious Diseases | Year: 2011

Background: Health care workers are exposed to patients with tuberculosis and are at risk of nosocomial infection. The aim of this study was to determine the prevalence and factors associated with latent tuberculosis infection among health care workers in Malaysia and also to evaluate the agreement between Quantiferon TB Gold in tube test with Tuberculin Skin Test.Methods: A cross sectional study was conducted at four randomly selected hospitals in the Klang Valley from December 2008 to May 2009. Self administered questionnaire was used to obtain information on health care workers and possible risk factors. The response rate for this study was 90.8% with 954 respondents completed the questionnaire and were tested with Quantiferon TB Gold in tube for latent tuberculosis infection. Agreement between Quantiferon TB Gold in tube and Tuberculin Skin Test was assessed among 95 health care workers who consented to undergo both tests.Results: The overall prevalence of latent tuberculosis infection among health care workers was 10.6% (CI: 8.6%; 12.6%). Factors significantly associated with latent tuberculosis infection were aged 35 years and older [9.49 (CI: 2.22; 40.50)], history of living in the same house with close family members or friends who had active tuberculosis [8.69 (CI: 3.00; 25.18)], worked as a nurse [4.65 (CI: 1.10; 19.65)] and being male [3.70 (CI: 1.36; 10.02)]. Agreement between Quantiferon TB Gold in tube test and tuberculin skin test at cut-off points of 10 mm and 15 mm was 50.5% and 82.1% respectively. However, Kappa-agreement was poor for both cut-off points.Conclusion: The prevalence of latent tuberculosis infection in Malaysia was relatively low for an intermediate TB burden country. We could not comment on the occupational risk of latent tuberculosis infection among health care worker compared to the general population as there were no prevalence data available for latent tuberculosis infection in the general population. Kappa agreement between Quantiferon TB gold in-tube and tuberculin skin test was poor. © 2011 Rafiza et al; licensee BioMed Central Ltd.

Ng S.-F.,University of New South Wales | Ng S.-F.,National University of Malaysia | Lin R.C.Y.,University of New South Wales | Maloney C.A.,University of New South Wales | And 3 more authors.
FASEB Journal | Year: 2014

We previously showed that paternal high-fat diet (HFD) consumption programs β-cell dysfunction in female rat offspring, together with transcriptome alterations in islets. Here we investigated the retroperitoneal white adipose tissue (RpWAT) transcriptome using gene and pathway enrichment and pathway analysis to determine whether commonly affected network topologies exist between these two metabolically related tissues. In RpWAT, 5108 genes were differentially expressed due to a paternal HFD; the top 5 significantly enriched networks identified by pathway analysis in offspring of HFD fathers compared with those of fathers fed control diet were: mitochondrial and cellular response to stress, telomerase signaling, cell death and survival, cell cycle, cellular growth and proliferation, and cancer. A total of 187 adipose olfactory receptor genes were down-regulated. Interrogation against the islet transcriptome identified specific gene networks and pathways, including olfactory receptor genes that were similarly affected in both tissues (411 common genes, P<0.05). In particular, we highlight a common molecular network, cell cycle and cancer, with the same hub gene, Myc, suggesting early onset developmental changes that persist, shared responses to programmed systemic factors, or crosstalk between tissues. Thus, paternal HFD consumption triggers unique gene signatures, consistent with premature aging and chronic degenerative disorders, in both RpWAT and pancreatic islets of daughters. © FASEB.

Yaakob Z.,National University of Malaysia | Sukarman I.S.B.,National University of Malaysia | Narayanan B.,Sree Neelakanta Government Sanskrit College | Abdullah S.R.S.,National University of Malaysia | Ismail M.,National University of Malaysia
Bioresource Technology | Year: 2012

Transesterification reaction of Jatropha curcas oil with methanol was carried out in the presence of ash generated from Palm empty fruit bunch (EFB) in a heterogeneous catalyzed process. The ash was doped with KOH by impregnation to achieve a potassium level of 20. wt.%. Under optimum conditions for the EFB-catalyzed (65 °C, oil/methanol ratio of 15, 90. min, 20. wt.% EFB ash catalyst) and the KOH-EFB-catalyzed reactions (65 °C, oil/methanol ratio of 15, 45. min, 15. wt.% of KOH doped EFB ash), biodiesel (>98%) with specifications higher than those stipulated by European biodiesel quality standard EN 14214 was obtained. © 2011 Elsevier Ltd.

Sharif R.,CSIRO | Sharif R.,University of Adelaide | Sharif R.,National University of Malaysia | Thomas P.,CSIRO | And 2 more authors.
Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis | Year: 2012

Zinc (Zn) is an essential trace element required for maintaining both optimal human health and genomic stability. Zn plays a critical role in the regulation of DNA repair mechanisms, cell proliferation, differentiation and apoptosis involving the action of various transcriptional factors and DNA or RNA polymerases. Zn is an essential cofactor or structural component for important antioxidant defence proteins and DNA repair enzymes such as Cu/Zn SOD, OGG1, APE and PARP and may also affect activities of enzymes such as BHMT and MTR involved in methylation reactions in the folate-methionine cycle. This review focuses on the role of Zn in the maintenance of genome integrity and the effects of deficiency or excess on genomic stability events and cell death. © 2011 Elsevier B.V.

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.

Chongsuvivatwong V.,Prince of Songkla University | Phua K.H.,National University of Singapore | Yap M.T.,Institute of Policy Studies | Pocock N.S.,National University of Singapore | And 4 more authors.
The Lancet | Year: 2011

Southeast Asia is a region of enormous social, economic, and political diversity, both across and within countries, shaped by its history, geography, and position as a major crossroad of trade and the movement of goods and services. These factors have not only contributed to the disparate health status of the region's diverse populations, but also to the diverse nature of its health systems, which are at varying stages of evolution. Rapid but inequitable socioeconomic development, coupled with differing rates of demographic and epidemiological transitions, have accentuated health disparities and posed great public health challenges for national health systems, particularly the control of emerging infectious diseases and the rise of non-communicable diseases within ageing populations. While novel forms of health care are evolving in the region, such as corporatised public health-care systems (government owned, but operating according to corporate principles and with private-sector participation) and financing mechanisms to achieve universal coverage, there are key lessons for health reforms and decentralisation. New challenges have emerged with rising trade in health services, migration of the health workforce, and medical tourism. Juxtaposed between the emerging giant economies of China and India, countries of the region are attempting to forge a common regional identity, despite their diversity, to seek mutually acceptable and effective solutions to key regional health challenges. In this first paper in the Lancet Series on health in southeast Asia, we present an overview of key demographic and epidemiological changes in the region, explore challenges facing health systems, and draw attention to the potential for regional collaboration in health. © 2011 Elsevier Ltd.

Turky A.M.,National University of Malaysia | Turky A.M.,Swinburne University of Technology | Abdullah S.,National University of Malaysia
Information Sciences | Year: 2014

Dynamic optimization problems present great challenges to the research community because their parameters are either revealed or changed during the course of an ongoing optimization process. These problems are more challenging than static problems in real-world applications because the latter are usually dynamic, with the environment constantly subjected to change or the size of a problem increasing sporadically. In solving dynamic optimization problems in the real world, proposed solutions should be able to monitor the movement of the optimal point and the changes in the landscape solutions. In this paper, a multi-population harmony search algorithm with external archive for dynamic optimization problems is proposed. Harmony search algorithm is a population-based meta-heuristic optimization technique that is similar to a musical process when a musician is attempting to find a state of harmony. To tackle the problem of dynamism, the population of solutions is divided into several sub-populations such that each sub-population takes charge exploring or exploiting the search space. To enhance the algorithm performance further, an external archive is used to save the best solutions for later use. These solutions will then be used to replace redundant solutions in the harmony memory. The proposed algorithm is tested on the Moving Peak Benchmark. Empirical results show that the proposed algorithm produces better results than several of the current state-of-the-art algorithms. © 2014 Elsevier Inc. All rights reserved.

Sulong A.B.,National University of Malaysia
Advanced Materials Research | Year: 2012

The capable of structures to absorb large amount energy are great interest in an effort to reduce the impact of collision. In this research, an experimental investigation was carried out to study the crashworthiness parameter and behavior of pultruded fiber E-glass/polyester composite tubes subjected to oblique load during progressive collapses. Two different pultruded wall thicknesses of 6 mm and 9 mm tubes were used and four load angles of 0°, 5°, 10° and 15° were selected to study their effect on crushing behaviors and collapse modes. All specimens were chamfer 45° on top end as purpose to work as a collapse trigger mechanism. The result showed that increasing the angle of loading will decrease the energy absorption of the structures. Pultruded tubes with 9 mm thick wall absorb more energy compare to 6 mm thick walls. © (2012) Trans Tech Publications, Switzerland.

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.

Saadatian O.,National University of Malaysia | Sopian K.,National University of Malaysia | Salleh E.,National University of Malaysia | Lim C.H.,National University of Malaysia | And 4 more authors.
Renewable and Sustainable Energy Reviews | Year: 2013

Global warming, depletion of natural resources, acid rains, air and water pollutions, and ozone depletions are some of the environmental consequences that are deemed attributable to human activities on planet earth. Sustainable practices have been therefore evolved as main remedies to tackles these issues. Green roof strategy is one of these practices that not only provides heat island amelioration and thermal comfort for occupants but also reduces energy consumption of buildings as well as add aesthetic values to the environment. This paper targets to run a review on the application of green roof strategy. The review scans a time frame from 2002 through early 2012 with a focus on energy related topics on energy related topics of green roofs. The review discussed various types of green roofs, components of a green roof, economic revenues, and technical attributes. Many general advantages and few general disadvantages of green roofs in one hand and pros and cons of green roofs with respect to energy utilization on the other hand are also synthesized. Some recommendations for future study are also proposed. © 2013 Elsevier Ltd.

MEDFORD, N.Y., Nov. 04, 2016 (GLOBE NEWSWIRE) -- Chembio Diagnostics, Inc. (Nasdaq:CEMI), a leader in point-of-care (POC) diagnostic tests for infectious diseases, today announced the Company has entered into an agreement to acquire RVR Diagnostics Sdn Bhd (RVR), a Malaysian, privately-held manufacturer and distributor of POC diagnostic tests for infectious diseases. Under the terms of the agreement, Chembio will pay up to US$1.5 million in cash and up to US$2 million in Chembio stock, based on the achievement of certain milestones, and Chembio also will forgive US$250,000 currently owed by RVR to Chembio. The transaction, which is subject to completion of certain due diligence and other matters, is expected to close during the first quarter of 2017, at which time RVR will become a wholly-owned subsidiary of Chembio. In 2014, Chembio and RVR entered into two agreements through which RVR acquired rights to license, manufacture and distribute certain Chembio products, including exclusive distribution rights for Chembio's DPP® HIV 1/2 Assay and DPP® HIV-Syphilis Assay in Southeast Asia.  Since entering into these agreements, RVR has achieved a number of important milestones, including: Considering the progress made by RVR, the acquisition of RVR provides Chembio with additional revenue, as well as a strategically located and cost-effective manufacturing facility that will be important in serving a number of global markets, including the rapidly growing Asian markets. John Sperzel, Chembio's CEO, commented, "Our growth plans include expansion into the Asia Pacific region, and we believe a corporate presence in Malaysia, which is centrally located in Southeast Asia, will be a key success factor. The RVR team has made excellent progress to establish a high-quality, low-cost manufacturing facility, which recently obtained ISO 13485 certification. We believe the combination of RVR’s cost-effective manufacturing competence and Chembio’s patented DPP® technology will allow Chembio to accelerate product registrations within Southeast Asia, where the population exceeds 600 million, and, also to build a stronger presence in other regions." Mac Vajuram, RVR’s Managing Director, commented, "We established RVR with the goal of becoming a leading supplier and distributor of high quality point-of-care diagnostic products in Asia. Since its inception, RVR has been capitalized with a combination of the founders' investments, public grants and research support from the National University of Malaysia, the country's premier university. Our partnership with Chembio, and our presence in Malaysia, has positioned RVR for success, and we believe this transaction will create additional growth opportunities in Asia and other markets.” Chembio Diagnostics, Inc. develops, manufactures, licenses and markets proprietary rapid diagnostic tests in the growing $8.0 billion point-of-care testing market. Chembio markets each of its DPP® HIV 1/2 Assay, HIV 1/2 STAT-PAK® Assay, and SURE CHECK® HIV 1/2 Assay, with these Chembio brand names, in the U.S. and internationally both directly and through third-party distributors.  The Company's SURE CHECK® HIV 1/2 Assay previously has been exclusively sold in the U.S. as Clearview® Complete HIV 1/2 Assay. Chembio has developed a patented point-of-care (POC) test platform technology, the Dual Path Platform (DPP®) technology, which has significant advantages over lateral-flow technologies. This technology is providing Chembio with a significant pipeline of business opportunities for the development and manufacture of new products. Headquartered in Medford, NY, Chembio is licensed by the U.S. Food and Drug Administration (FDA) as well as the U.S. Department of Agriculture (USDA), and is certified for the global market under the International Standards Organization (ISO) directive 13485. Chembio Diagnostic Systems Inc. is a wholly-owned subsidiary of Chembio Diagnostics, Inc. For more information, please visit: www.chembio.com. Statements contained herein that are not historical facts may be forward-looking statements within the meaning of the Securities Act of 1933, as amended. Forward-looking statements include statements regarding the intent, belief or current expectations of the Company and its management. Such statements, which are estimates only, reflect management's current views, are based on certain assumptions, and involve risks and uncertainties. Actual results, events, or performance may differ materially from the above forward-looking statements due to a number of important factors, and will be dependent upon a variety of factors, including, but not limited to Chembio's ability to obtain additional financing and to obtain regulatory approvals in a timely manner, as well as the demand for Chembio's products. Chembio undertakes no obligation to publicly update these forward-looking statements to reflect events or circumstances that occur after the date hereof or to reflect any change in Chembio's expectations with regard to these forward-looking statements or the occurrence of unanticipated events. Factors that may impact Chembio's success are more fully disclosed in Chembio's most recent public filings with the U.S. Securities and Exchange Commission.

Sufiza Ahmad N.,Ministry of Health | Ramli A.,Ministry of Health | Islahudin F.,National University of Malaysia | Paraidathathu T.,National University of Malaysia
Patient Preference and Adherence | Year: 2013

Purpose: Diabetes mellitus is a growing global health problem that affects patients of all ages. Even though diabetes mellitus is recognized as a major chronic illness, adherence to antidiabetic medicines has often been found to be unsatisfactory. This study was conducted to assess adherence to medications and to identify factors that are associated with nonadherence in type 2 diabetes mellitus (T2DM) patients at Primary Health Clinics of the Ministry of Health in Malaysia. Materials and methods: The cross-sectional survey was carried out among T2DM patients to assess adherence to medication in primary health clinics. Adherence was measured by using the Medication Compliance Questionnaire that consists of a total of seven questions. Other data, such as patient demographics, treatment, outcome, and comorbidities were also collected from patient medical records. Results: A total of 557 patients were recruited in the study. Approximately 53% of patients in the study population were nonadherent. Logistic regression analysis was performed to predict the factors associated with nonadherence. Variables associated with nonadherence were age, odds ratio 0.967 (95% confidence interval [CI]: 0.948-0.986); medication knowledge, odds ratio 0.965 (95% CI: 0.946-0.984); and comorbidities, odds ratio 1.781 (95% CI: 1.064-2.981). Conclusion: Adherence to medication in T2DM patients in the primary health clinics was found to be poor. This is a cause of concern, because nonadherence could lead to a worsening of disease. Improving medication knowledge by paying particular attention to different age groups and patients with comorbidities could help improve adherence. © 2013 Ahmad et al, publisher and licensee Dove Medical Press Ltd.

Halib N.,Malaysian Nuclear Agency | Amin M.C.I.M.,National University of Malaysia | Ahmad I.,National University of Malaysia
Journal of Applied Polymer Science | Year: 2010

The formation and swelling behavior of bacterial cellulose/acrylic acid hydrogel prepared from aqueous mixture consists of 20 : 80 (v/v) acrylic acid (AAc) and 1% bacterial cellulose dispersion under accelerated electron beam was investigated. Gel fraction of hydrogel increased with the increasing dose suggesting a denser composite at 50 kGy compared to 35 kGy. SEM photomicrographs revealed a homogenous pores distribution at higher dose with pore sizes ranging from 1 to 5 lm. Hydrogel synthesized at lower dose of electron beam exhibited higher swelling ability and the degree of swelling increased as the pH of surrounding medium increased and it reached the optimum swelling at pH 7. While swelling of the hydrogel decreased with the increasing ionic strength of solution, swelling at different temperatures ranging from 25 to 50°C revealed a unique character where the hydrogel shrunk at 37°C. Moreover, hydrogel synthesized at higher dose exhibited a higher degree of swelling in methanol with respect to water. © 2010 Wiley Periodicals, Inc.

Razak R.A.,Multimedia University | Ismail N.,National University of Malaysia
AIP Conference Proceedings | Year: 2014

Return series of stock markets tend to have leptokurtic distribution thus making linear correlation an inappropriate measure of dependence. Copula theory can be used as an alternative to show the dependencies between return series. In this paper, we study the dependence structure of extreme returns between several Asia-Pacific stock markets by applying the Copula based marginal GARCH approach. The results of our study are discussed in this paper. © 2014 AIP Publishing LLC.

Rashwan H.H.,University Technology of MARA | Saat N.Z.N.M.,National University of Malaysia | Manan D.N.A.,Ministry of Health
Asian Pacific Journal of Cancer Prevention | Year: 2012

Human Papillomavirus (HPV) infection is one of the most common sexually transmitted infections and oncogenic HPV is the main cause of cervical cancer. However, HPV vaccination is already available as the primary preventive method against cervical cancer. The objective of this study was to determine the level of knowledge, attitude and practice of HPV vaccination among Universiti Kebangsaan Malaysia (UKM) and Universiti Malaya (UM) students. This study was conducted from March until August 2009. Pre-tested and validated questionnaires were filled by the third year UKM (n=156) and UM (n=149) students from medical, dentistry and pharmacy faculties. The results showed that the overall level of knowledge on HPV infection, cervical cancer and its prevention among respondents was high and themajority of them had positive attitude towards HPV vaccination. Medical students had the highest level of knowledge (p<0.05). Very few students (3.6%) had already taken the vaccine with no significant difference between the two Universities (p=0.399). In conclusion, the knowledge and attitude of the respondents were high and positive, respectively. Only few students took HPV vaccination. Thus, more awareness campaigns and HPV vaccination services should be provided at universities' campuses with the price of the HPV vaccine reduced for the students.

Mohd Amin M.C.I.,National University of Malaysia | Ahmad N.,National University of Malaysia | Halib N.,Malaysian Nuclear Agency | Ahmad I.,National University of Malaysia
Carbohydrate Polymers | Year: 2012

To assist in identifying the utility of novel materials in drug-delivery applications, this study investigated the use of bacterial cellulose (BC), a natural biopolymer, in the synthesis of hydrogels for drug-delivery systems. BC was combined with different proportions of acrylic acid (AA) to fabricate hydrogels by exposure to accelerated electron-beam irradiation at different doses. Fourier transform infrared analysis revealed that the AA had been successfully grafted onto the cellulose fibers and allowed for prediction of the reaction mechanism in the synthesis of hydrogels. Thermal and morphological characterization indicated the formation of thermally stable hydrogels with pore size determined by AA content and irradiation dose. The results of swelling and in vitro drug-release studies revealed the hydrogels to be both thermo- and pH-responsive. Such thermo- and pH-responsiveness, in addition to their morphological characteristics, suggests that these BC/AA hydrogels are promising candidates as controlled drug-delivery systems. © 2011 Elsevier Ltd. All rights reserved.

Fadhel M.I.,National University of Malaysia | Fadhel M.I.,Multimedia University | Sopian K.,National University of Malaysia | Daud W.R.W.,National University of Malaysia | Alghoul M.A.,National University of Malaysia
Renewable and Sustainable Energy Reviews | Year: 2011

Over the past three decades there has been nearly exponential growth in drying R&D on a global scale. Improving of the drying operation to save energy, improve product quality as well as reduce environmental effect remained as the main objectives of any development of drying system. A solar assisted chemical heat pump dryer is a new solar drying system, which have contributed to better cost-effectiveness and better quality dried products as well as saving energy. A solar collector is adapted to provide thermal energy in a reactor so a chemical reaction can take place. This reduces the dependency of the drying technology on fossil energy for heating. In this paper a review on advanced of solar assisted chemical heat pump dryer is presented (the system model and the results from experimental studies on the system performance are discussed). The review of heat pump dryers and solar assisted heat pump dryer is presented. Description of chemical heat pump types and the overview of chemical heat pump dryer are discussed. The combination of chemical heat pump and solar technology gives extra efficiency in utilizing energy. © 2010 Elsevier Ltd. All rights reserved.

Choudhury P.K.,National University of Malaysia | Soon W.K.,Multimedia University
Optik | Year: 2011

A three-layer liquid crystal tapered optical fiber (LCTF) is investigated with the emphasis on the power confinements by the low order TE and TM modes sustained in the different sections of LCTF. The outermost clad section is considered to be made of liquid crystal with radial anisotropy whereas the core and the inner clad are dielectric regions. Rigorous field expressions in the different LCTF sections are deduced, and the plots of power confinement factors (or the relative distributions) are ultimately made considering different fiber dimensions. The results reveal that the TE modes confine maximum amount of power in the outermost liquid crystal region, which is attributed to the radial anisotropy of the section. Such features of LCTFs attract their usefulness in the area of field coupling devices and optical sensing where evanescent field technique is primarily implemented. © 2010 Elsevier GmbH. All rights reserved.

Alam M.R.,Carleton University | Reaz M.B.I.,National University of Malaysia | Ali M.A.M.,National University of Malaysia
IEEE Transactions on Systems, Man and Cybernetics Part C: Applications and Reviews | Year: 2012

A smart home is an application of ubiquitous computing in which the home environment is monitored by ambient intelligence to provide context-aware services and facilitate remote home control. This paper presents an overview of previous smart home research as well as the associated technologies. A brief discussion on the building blocks of smart homes and their interrelationships is presented. It describes collective information about sensors, multimedia devices, communication protocols, and systems, which are widely used in smart home implementation. Special algorithms from different fields and their significance are explained according to their scope of use in smart homes. This paper also presents a concrete guideline for future researchers to follow in developing a practical and sustainable smart home. © 1998-2012 IEEE.

Rusbintardjo G.,Islamic University of Sultan Agung | Hainin M.R.,University of Technology Malaysia | Yusoff N.I.M.,National University of Malaysia
Construction and Building Materials | Year: 2013

This study was conducted to investigate the suitability of using oil palm fruit ash (OPFA) as a bitumen modifier. The OPFA was used to fulfil all bitumen modification requirements, as well as to take advantage of a waste by-product of the palm oil mill industry which could help to reduce environmental pollution. Twenty-four OPFA-modified bitumens (OPFA-MBs) were produced by the laboratory mixing of normal bitumen (80/100) from two sources with Fine and Coarse OPFAs of six different contents. This process was conducted at a mixing temperature of 160 C, a mixing time of 60 min and a mixing stirring speed of 800 rpm. The consistency and rheological characteristics of the OPFA-MBs were analysed by means of conventional as well as dynamic mechanical analysis using dynamic shear rheometer (DSR), bending beam rheometer (BBR) and direct tension test (DTT). The results of the investigation indicate that binder compounded with OPFA becomes less susceptible to temperature, improve resistance to rutting at 70 C, fatigue cracking at 20 C, and thermal cracking at -17 C of the surface pavement temperature compared to the unmodified bitumen. The OPFA-MB can be categorised as a binder with penetration grade of 60/70 or as PG 70-16 in the performance based system. Finally, it can be deduced that it is feasible to use OPFA as a modifier of bitumen.© 2013 Elsevier Ltd. All rights reserved.

Zahi S.,Multimedia University | Zahi S.,National University of Malaysia | Daud A.R.,National University of Malaysia
Materials and Design | Year: 2011

Continuing study in metallurgical field calls for growing reinforcements of which fly ash plays an important role. In this study, Al alloys were reinforced with different solid fly ash particles. The X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray fluorescence (XRF) analyses were used to identify the fly ash particles, and they were also applied to the composite alloys. The X-ray diffraction (XRD) results indicated that the crystalline phase of the fly ash was an effective reinforced phase. Meanwhile, the SEM and optical micrographs of the composite samples indicated that fly ash could be reacted or settled in the matrix of the aluminium. The physical, tribological and microhardness analyses were also used to study the Al-fly ash composites. The best wear resistance corresponding to the lowest loss was obtained in the samples with as-received fly ash which were mostly in accordance with the results in the samples containing treated fly ash. Meanwhile, the proportion of the wear results to the hardness of the samples was observed. Finally, the light weight Al alloys was realized, and increasing the strength is a likeness. © 2010 Elsevier Ltd.

Ramli A.,Ministry of Health | Ahmad N.S.,Ministry of Health | Paraidathathu T.,National University of Malaysia
Patient Preference and Adherence | Year: 2012

Purpose: Poor adherence to prescribed medications is a major cause for treatment failure, particularly in chronic diseases such as hypertension. This study was conducted to assess adherence to medications in patients undergoing hypertensive treatment in the Primary Health Clinics of the Ministry of Health in Malaysia. Factors affecting adherence to medications were studied, and the effect of nonadherence to blood pressure control was assessed. Patients and methods: This was a cross-sectional study to assess adherence to medications by adult patients undergoing hypertensive treatment in primary care. Adherence was measured using a validated survey form for medication adherence consisting of seven questions. A retrospective medication record review was conducted to collect and confirm data on patients' demographics, diagnosis, treatments, and outcomes. Results: Good adherence was observed in 53.4% of the 653 patients sampled. Female patients were found to be more likely to adhere to their medication regime, compared to their male counterparts (odds ratio 1.46 [95% confidence intervals [CI]: 1.05-2.04; P < 0.05]). Patients in the ethnic Chinese were twice as likely (95% CI: 1.14-3.6; P < 0.05) to adhere, compared to those in the Indian ethnic group. An increase in the score for medicine knowledge was also found to increase the odds of adherence. On the other hand, increasing the number of drugs the patient was taking and the daily dose frequencies of the medications prescribed were found to negatively affect adherence. Blood pressure control was also found to be worse in noncompliers. Conclusion: The medication adherence rate was found to be low among primary care hypertensive patients. A poor adherence rate was found to negatively affect blood pressure control. Developing multidisciplinary intervention programs to address the factors identified is necessary to improve adherence and, in turn, to improve blood pressure control. © 2012 Ramli et al, publisher and licensee Dove Medical Press Ltd.

Choudhury P.K.,National University of Malaysia | Soon W.K.,Multimedia University
Progress in Electromagnetics Research | Year: 2010

An analysis is presented of a three-layer tapered core liquid crystal optical fiber (TLCF) having the outermost clad section made of radially anisotropic liquid crystal. TE mode propagation through TLCF is demonstrated with maximum distribution of power in the liquid crystal section under the situation that the TLCF core and the inner clad regions are constructed of homogeneous and isotropic dielectric materials. Such a propagation feature is attributed to the radial anisotropy of the liquid crystal outer region, and attracts useful applications of TLCFs in evanescent field optical sensing and other coupling devices primarily used in integrated optics.

Md. Yusoff N.I.,National University of Malaysia | Mounier D.,Civil Aviation Technical Center | Marc-Stephane G.,Laboratoire Regional des Ponts et Chaussees dAix en Provence LRPC | Rosli Hainin M.,University of Technology Malaysia | And 2 more authors.
Construction and Building Materials | Year: 2013

This study evaluates the suitability of the 2S2P1D Model to describe the rheological properties of a large database of bituminous binders held by the Nottingham Transportation Engineering Centre. This database includes more than 60 different combinations of unmodified bitumen, polymer-modified bitumen and bitumen-filler mastics, unaged and aged samples. The 2S2P1D Model is found to be able to satisfactorily describe the linear viscoelastic rheological (LVE) properties of binders over a wide range of temperatures and frequencies. A comparison between measured and descriptive complex modulus and phase angle data was done using a graphical method and goodness-of-fit statistics. Except for the unaged polymer-modified bitumens, all tested samples show good agreement between the measured and descriptive data. © 2012 Elsevier Ltd. All rights reserved.

Choudhury P.K.,National University of Malaysia | Kumar D.,Multimedia University
Journal of Electromagnetic Waves and Applications | Year: 2010

Lightwave propagation through dielectric helical clad elliptical fibers is presented under the slow-wave consideration. The helical clad is achieved by putting helical turns on the core-clad interface. While treating analytically, two extreme cases of helix pitch angle - i.e., 0° and 90° - are considered along with the use of slowwave approximation. E- and H-field components are determined in the different sections of the guide followed by the evolution of the eigenvalue relation. The effect of ellipse eccentricity is determined on the dispersion characteristics for different operating wavelengths and corresponding to different values of the length of core semi-major axis. © 2010 VSP.

Othman J.,National University of Malaysia | Sahani M.,National University of Malaysia | Mahmud M.,National University of Malaysia | Sheikh Ahmad M.K.,Health Informatics Center
Environmental Pollution | Year: 2014

This study assessed the economic value of health impacts of transboundary smoke haze pollution in Kuala Lumpur and adjacent areas in the state of Selangor, Malaysia. Daily inpatient data from 2005, 2006, 2008, and 2009 for 14 haze-related illnesses were collected from four hospitals. On average, there were 19 hazy days each year during which the air pollution levels were within the Lower Moderate to Hazardous categories. No seasonal variation in inpatient cases was observed. A smoke haze occurrence was associated with an increase in inpatient cases by 2.4 per 10,000 populations each year, representing an increase of 31 percent from normal days. The average annual economic loss due to the inpatient health impact of haze was valued at MYR273,000 ($91,000 USD). © 2014 Elsevier Ltd. All rights reserved.

Farhadi M.,Islamic Azad University at Mobarakeh | Ismail R.,National University of Malaysia | Fooladi M.,Islamic Azad University at Mobarakeh
PLoS ONE | Year: 2012

In recent years, progress in information and communication technology (ICT) has caused many structural changes such as reorganizing of economics, globalization, and trade extension, which leads to capital flows and enhancing information availability. Moreover, ICT plays a significant role in development of each economic sector, especially during liberalization process. Growth economists predict that economic growth is driven by investments in ICT. However, empirical studies on this issue have produced mixed results, regarding to different research methodology and geographical configuration of the study. This paper examines the impact of Information and Communication Technology (ICT) use on economic growth using the Generalized Method of Moments (GMM) estimator within the framework of a dynamic panel data approach and applies it to 159 countries over the period 2000 to 2009. The results indicate that there is a positive relationship between growth rate of real GDP per capita and ICT use index (as measured by the number of internet users, fixed broadband internet subscribers and the number of mobile subscription per 100 inhabitants). We also find that the effect of ICT use on economic growth is higher in high income group rather than other groups. This implies that if these countries seek to enhance their economic growth, they need to implement specific policies that facilitate ICT use. © 2012 Farhadi et al.

Zan M.S.D.B.,Shibaura Institute of Technology | Zan M.S.D.B.,National University of Malaysia | Horiguchi T.,Shibaura Institute of Technology
Journal of Lightwave Technology | Year: 2012

We propose in this paper to configure a dual Golay complementary pair of sequences (DGCP) by nesting one Golay complementary pair of sequences (GCP) into the other GCP. We show that the DGCP also has the unique property that the side lobes of the correlation functions are cancelled exactly as the conventional GCP. The DGCP allows the simultaneous use of coded RZ-pulses and coded NRZ-pulses in the pump light of the Brillouin optical time-domain analysis (BOTDA). We call them in this paper coded discrete pulses and coded continuous pulses, respectively. The simultaneous use of both types of coded pulses for the BOTDA makes it possible to employ virtually longer code than the use of only one kind of coded pulses. We theoretically show the dependence of signal-to-noise ratio enhancement (SNRE) on the code length of the DGCP as well as on the code lengths of the GCPs used for the discrete and continuous pulses. Examination of the spatial resolution is also given. Experimental results illustrate the theoretical considerations; about 7 dB of SNRE and 10-cm of spatial resolution are achieved by using DGCP, being in accordance with the theory. © 2012 IEEE.

Eslami M.,Islamic Azad University at Tehran | Shareef H.,National University of Malaysia | Mohamed A.,National University of Malaysia
Journal of Central South University of Technology (English Edition) | Year: 2011

A novel technique for the optimal tuning of power system stabilizer (PSS) was proposed, by integrating the modified particle swarm optimization (MPSO) with the chaos (MPSOC). Firstly, a modification in the particle swarm optimization (PSO) was made by introducing passive congregation (PC). It helps each swarm member in receiving a multitude of information from other members and thus decreases the possibility of a failed attempt at detection or a meaningless search. Secondly, the MPSO and chaos were hybridized (MPSOC) to improve the global searching capability and prevent the premature convergence due to local minima. The robustness of the proposed PSS tuning technique was verified on a multi-machine power system under different operating conditions. The performance of the proposed MPSOC was compared to the MPSO, PSO and GA through eigenvalue analysis, nonlinear time-domain simulation and statistical tests. Eigenvalue analysis shows acceptable damping of the low-frequency modes and time domain simulations also show that the oscillations of synchronous machines can be rapidly damped for power systems with the proposed PSSs. The results show that the presented algorithm has a faster convergence rate with higher degree of accuracy than the GA, PSO and MPSO. © Central South University Press and Springer-Verlag Berlin Heidelberg 2011.

Hatamlou A.,Islamic Azad University at Khoy | Hatamlou A.,National University of Malaysia
Information Sciences | Year: 2013

Nature has always been a source of inspiration. Over the last few decades, it has stimulated many successful algorithms and computational tools for dealing with complex and optimization problems. This paper proposes a new heuristic algorithm that is inspired by the black hole phenomenon. Similar to other population-based algorithms, the black hole algorithm (BH) starts with an initial population of candidate solutions to an optimization problem and an objective function that is calculated for them. At each iteration of the black hole algorithm, the best candidate is selected to be the black hole, which then starts pulling other candidates around it, called stars. If a star gets too close to the black hole, it will be swallowed by the black hole and is gone forever. In such a case, a new star (candidate solution) is randomly generated and placed in the search space and starts a new search. To evaluate the performance of the black hole algorithm, it is applied to solve the clustering problem, which is a NP-hard problem. The experimental results show that the proposed black hole algorithm outperforms other traditional heuristic algorithms for several benchmark datasets. © 2012 Elsevier Inc. All rights reserved.

Hao H.M.,University Tunku Abdul Rahman | Jaafar A.,National University of Malaysia
Proceedings of the 2011 International Conference on Pattern Analysis and Intelligent Robotics, ICPAIR 2011 | Year: 2011

Usability has been plagued in many years since the birth of the term called human computer interaction. Many studies have proved numerous benefits gained from usability, from the software product specifically to the business as a whole. Moreover, international standards, and guidelines have incorporated usability in the quality assessment. As there is growth of software consultancy industry in the recent years and the concept and theories have been introduced in the education curriculum in Malaysia, we are wondering if the practice of usability is in the ICT industry specifically in the interactive computer-based system. We have developed a preliminary qualitative and quantitative assessment for both managers and practitioners in the ICT companies in Klang valley, Malaysia. The purpose of the assessment is to understand and to evaluate the practice of usability among practitioners in ICT companies in Malaysia. The research uses both structured questionnaire and follow-up by semi-structured interview either through face-to-face or email. The pilot result shows that average scale range from 4 to 4.6 out of 5 perceptively and practically importance putting usability in determines a project success, average scale range from 3.4 to 3.8 out of 5 agree to put usability concept in their practice of design and development, and average scale range from 3.8 to 4.1 out of 5 perceptively and practically importance to include usability criteria in their designed system. © 2011 IEEE.

Al Mamun M.,La Trobe University | Sohag K.,National University of Malaysia | Hannan Mia M.A.,University of Dhaka | Salah Uddin G.,Linköping University | Ozturk I.,Cag University
Renewable and Sustainable Energy Reviews | Year: 2014

Environmental degradation measured by CO2 emissions is a significant challenge to sustainable economic development. Owing to significant differences in the empirical relationship between the economic growth and CO2 emissions and policies adopted by different countries to overcome the challenge are not decisive. This study aims to generalize our knowledge about the relationship between CO2 emissions per capita and economic growth across the world for 1980-2009 periods. Besides, it explores whether the transformation of different economies (e.g. agrarian to industrial and industrial to sophisticated service economy) over the past few decades yielded any significant positive impact towards sustainable economic development by reducing the level of CO2 emission. Empirical results suggest that (i) except for high-income-countries, Environmental Kuznets Curve (EKC) is a general phenomenon across the world, and (ii) the transformation of different economies towards a service economy has produced more pollution in high income countries and less pollution in low and middle income countries. © 2014 Elsevier Ltd.

Wahid N.B.A.,National University of Malaysia | Wahid N.B.A.,Sultan Idris University of Education | Latif M.T.,National University of Malaysia | Suratman S.,University of Malaysia, Terengganu
Chemosphere | Year: 2013

This study was conducted to determine the composition and source apportionment of surfactant in atmospheric aerosols around urban and semi-urban areas in Malaysia based on ionic compositions. Colorimetric analysis was undertaken to determine the concentrations of anionic surfactants as Methylene Blue Active Substances (MBAS) and cationic surfactants as Disulphine Blue Active Substances (DBAS) using a UV spectrophotometer. Ionic compositions were determined using ion chromatography for cations (Na+, NH4+, K+, Mg2+, Ca2+) and anions (F-, Cl-, NO3-, SO42-). Principle component analysis (PCA) combined with multiple linear regression (MLR) were used to identify the source apportionment of MBAS and DBAS. Results indicated that the concentrations of surfactants at both sampling sites were dominated by MBAS rather than DBAS especially in fine mode aerosols during the southwest monsoon. Three main sources of surfactants were identified from PCA-MLR analysis for MBAS in fine mode samples particularly in Kuala Lumpur, dominated by motor vehicles, followed by soil/road dust and sea spray. Besides, for MBAS in coarse mode, biomass burning/sea spray were the dominant source followed by motor vehicles/road dust and building material. © 2012 Elsevier Ltd.

Fasahat P.,National University of Malaysia | Rahman S.,Monash University | Ratnam W.,National University of Malaysia
Journal of Genetics | Year: 2014

Starch accumulates in plants as granules in chloroplasts of source organs such as leaves (transitory starch) or in amyloplasts of sink organs such as seeds, tubers and roots (storage starch). Starch is composed of two types of glucose polymers: the essentially linear polymer amylose and highly branched amylopectin. The amylose content of wheat and rice seeds is an important quality trait, affecting the nutritional and sensory quality of two of the world's most important crops. In this review, we focus on the relationship between amylose biosynthesis and the structure, physical behaviour and functionality of wheat and rice grains. We briefly describe the structure and composition of starch and then in more detail describe what is known about the mechanism of amylose synthesis and how the amount of amylose in starch might be controlled. This more specifically includes analysis of GBSS alleles, the relationship between waxy allelic forms and amylose, and related quantitative trait loci. Finally, different methods for increasing or lowering amylose content are evaluated. © 2014 Indian Academy of Sciences.

Koo C.H.,University Tunku Abdul Rahman | Mohammad A.W.,National University of Malaysia | Suja' F.,National University of Malaysia
Desalination | Year: 2011

Currently, awareness of water conservation has increased worldwide due to water scarcity. Wastewater recycling appears to be attractive for water conservation. This paper addresses a case study of oleochemical wastewater treatment using an advanced process that comprises ultrafiltration (UF) and reverse osmosis (RO) membranes. Prior to the membrane process, the oleochemical effluent was first treated using a biological treatment system that was installed by the factory owner. The quantity and quality of the permeate stream of the membrane system were then periodically monitored over 43. days. The results showed that the system functioned effectively in reducing the chemical oxygen demand (COD), hardness content and the amount of total dissolved solids (TDS). However, the system started to deteriorate after 15. days of operation. Membrane biofouling was suspected to have occurred in the RO membrane. Nevertheless, the fouling problem could be resolved by chemically cleaning the RO membrane using a sodium hydroxide (NaOH) solution every 3-5. days. Despite of the fact that data set for a longer period is needed to provide a more comprehensive study on the biofouling mechanism of membrane, this study somehow reflects a real-life problem of the application of RO membrane in the water recycling industry in Malaysia. © 2010 Elsevier B.V.

Hatamlou A.,Islamic Azad University at Khoy | Hatamlou A.,National University of Malaysia
Pattern Recognition Letters | Year: 2012

Data clustering is an important technique in data mining. It is a method of partitioning data into clusters, in which each cluster must have data of great similarity and different clusters must have data of high dissimilarity. A lot of clustering algorithms are found in the literature. In general, there is no single algorithm that is suitable for all types of data, conditions and applications. Each algorithm has its own advantages, limitations and shortcomings. Therefore, introducing novel and effective approaches for data clustering is an open and active research area. This paper presents a novel binary search algorithm for data clustering that not only finds high quality clusters but also converges to the same solution in different runs. In the proposed algorithm a set of initial centroids are chosen from different parts of the test dataset and then optimal locations for the centroids are found by thoroughly exploring around of the initial centroids. The simulation results using six benchmark datasets from the UCI Machine Learning Repository indicate that proposed algorithm can efficiently be used for data clustering. © 2012 Elsevier B.V. All rights reserved.

Koo C.H.,National University of Malaysia | Koo C.H.,University Tunku Abdul Rahman | Mohammad A.W.,National University of Malaysia | Suja' F.,National University of Malaysia | Meor Talib M.Z.,National University of Malaysia
Desalination | Year: 2012

Membrane fouling is one of the major drawbacks for membrane-based technologies because it leads to severe flux decline which requires the fouled membrane to be cleaned and replaced on a regular basis. A systematic approach that is capable of providing early diagnosis is essential to control membrane fouling. Fouling index is a measure for fouling propensity of water in reverse osmosis applications. The present paper focuses on the review from the existing literature of the various fouling indices, i.e. SDI and MFI associated with a number of selected physicochemical factors. Despite of the fact that the membrane fouling problems and their forming mechanisms have been studied by numerous researchers, the evaluation on the contributing factors towards the fouling propensity is still remained unclear. Membrane fouling propensity can be influenced by: membrane morphology (i.e. surface porosity, membrane material, membrane hydrophobicity, membrane molecular cut-off, pore size), feedwater composition (i.e. ionic strength, pH, types and concentrations of feed), and hydrodynamic conditions (i.e. crossflow velocity, permeate flux and temperature). These factors were discussed in great detail in the present review. © 2011 Elsevier B.V.

Ahmad K.,International Islamic University Malaysia | Nazar R.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
International Communications in Heat and Mass Transfer | Year: 2012

In this paper, the steady mixed convection boundary layer in laminar film flow of a micropolar fluid is considered. The resulting nonlinear coupled ordinary differential equations are solved numerically using an efficient implicit finite-difference scheme. The numerical results obtained for the skin friction coefficient and the local Nusselt number, as well as the velocity, angular velocity or microrotation and temperature profiles are presented in tables and figures for different values of the material parameter K and the Richardson number Ri when the Prandtl number Pr= 0.7 and Pr= 1. © 2011 Elsevier Ltd.

Al-Shamani A.N.,National University of Malaysia | Al-Shamani A.N.,Foundation of Technical Education | Yazdi M.H.,National University of Malaysia | Alghoul M.A.,National University of Malaysia | And 4 more authors.
Renewable and Sustainable Energy Reviews | Year: 2014

The use of nanofluids for cooling is an attracting considerable attention in various industrial applications. Compared with conventional fluids, nanofluids improve the heat transfer rate, as well as the optical properties, thermal properties, efficiency, and transmission and extinction coefficients of solar systems. The effects of different nanofluids on the cooling rate and hence the efficiency of solar systems can be experimentally investigated. Accordingly, this review paper presents the effects of nanofluids on the performance of solar collectors from the considerations of efficiency and environmental benefits. A review of literature shows that many studies have evaluated the potential of nanofluids for cooling different thermal systems. The second part of this paper presents an overview of the research, performance, and development of photovoltaic/thermal (PV/T) collector systems. Descriptions are made on water PV/T collector types, analytical and numerical models, and simulation and experimental works. The parameters affecting PV/T performance such as covered versus uncovered PV/T collectors, absorber plate parameters, and absorber configuration design types are extensively discussed. Exergy analysis shows that the coverless PV/T collector produces the largest total (electrical+thermal) exergy. Furthermore, PV/T collectors are observed to be very promising devices, and further work should be carried out to improve their efficiency and reduce their cost. Therefore, using nanofluids for cooling PV/T systems may be reasonable. © 2014 Elsevier Ltd.

Mohd-Padil H.,National University of Malaysia | Mohd-Adnan A.,National University of Malaysia | Gabaldon T.,Center for Genomic Regulation | Gabaldon T.,University Pompeu Fabra
Molecular Biology and Evolution | Year: 2013

Transferrin is a protein super-family involved in iron transport, a central process in cellular homeostasis. Throughout the evolution of vertebrates, transferrin members have diversified into distinct subfamilies including serotransferrin, ovotransferrin, lactoferrin, melanotransferrin, the inhibitor of carbonic anhydrase, pacifastin, and the major yolk protein in sea urchin. Previous phylogenetic analyses have established the branching order of the diverse transferrin subfamilies but were mostly focused on the transferrin repertoire present in mammals. Here, we conduct a comprehensive phylogenetic analysis of transferrin protein sequences in sequenced vertebrates, placing a special focus on the less-studied nonmammalian vertebrates. Our analyses uncover a novel transferrin clade present across fish, sauropsid, and amphibian genomes but strikingly absent from mammals. Our reconstructed scenario implies that this novel class emerged through a duplication event at the vertebrate ancestor, and that it was subsequently lost in the lineage leading to mammals. We detect footprints of accelerated evolution following the duplication event, which suggest positive selection and early functional divergence of this novel clade. Interestingly, the loss of this novel class of transferrin in mammals coincided with the divergence by duplication of lactoferrin and serotransferrin in this lineage. Altogether, our results provide novel insights on the evolution of iron-binding proteins in the various vertebrate groups. © 2012 The Author(s) 2012. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Khatib T.,Sohar University | Sopian K.,National University of Malaysia | Kazem H.A.,Sohar University
Energy Conversion and Management | Year: 2013

This paper presents a field operation experience for a grid connected PV system under tropical climate. The system is consisted of a 5 kWp photovoltaic (PV) array and a 6 kW DC/AC inverter. The operation performance data are recorded in order to develop accurate mathematical models for the system as well as to evaluate the productivity of the system. The experiment results show that, the average PV performance (the ratio of the theoretical performance to the actual performance) is 73.12% while the average inverter performance (the ratio of the theoretical inverter efficiency to the actual inverter efficiency) is 98.56%. Moreover, it is found that the daily yield factor of the PV system is 2.51 kW h/kWp day while, the capacity factor is 10.47%. However, it is concluded that the productivity of the system is below the prospected rate and thus, an inspection of the system must be done in order to diagnose the problem of the system's low productivity. This paper presents worthwhile information for those who are interested in PV system installation in Malaysia and nearby country.

Dyari H.R.E.,University of Sydney | Dyari H.R.E.,National University of Malaysia | Rawling T.,University of Technology, Sydney | Bourget K.,University of Sydney | Murray M.,University of Sydney
Journal of Medicinal Chemistry | Year: 2014

ω-3-17,18-Epoxyeicosapentaenoic acid decreases cell proliferation and activates apoptosis, whereas its regioisomers stimulate growth. We evaluated synthetic ω-3 epoxides of saturated fatty acids as antiproliferative and pro-apoptotic agents in MDA-MB-231 breast cancer cells. The epoxides, but not their urea, amide, or carbamate isosteres, impaired ATP production, enhanced caspase-3 activity, and activated c-jun-N-terminal-kinase signaling, leading to cyclin D1 down-regulation and cell cycle arrest in G1-phase. Fatty acid ω-3 monoepoxides may represent a novel class of antitumor agents. © 2014 American Chemical Society.

El-Shafie A.,National University of Malaysia | Najah A.,University of Malaysia, Terengganu | Alsulami H.M.,Ministry of Higher Education | Jahanbani H.,University of Melbourne
Water Resources Management | Year: 2014

Potential evapotranspiration (ETo) is an essential hydrologic parameter for having better understanding for hydrologic cycle in certain catchment area. In addition, ETo is vital for calculating the agricultural demand. In fact, Penman-Monteith (PM) method is considered as reference method for estimating (ETo), however, this method required a lot of data to be used which is not usually available in many catchment areas. Furthermore, there are several efforts that have been performed as competitor to reach accurate estimation of (ETo) when there is lack of data to utilize (PM) method, but still required numerous research. Recently, methods based on Artificial Intelligence (AI) have been suggested to provide reliable prediction model for several application in engineering and especially for hydrological process. However, time series prediction based on Artificial Neural Network (ANN) learning algorithms is fundamentally difficult and faces problem. One of the major shortcomings is that the ANN model experiences over-fitting problem during training session and also occurs when a neural network loses its generalization. In this research a modification for the classical Multi Layer Preceptron- Artificial Neural Network (MLP-ANN) modeling namely; Ensemble Neural Network (ENN) is proposed and applied for predicting daily ETo. The proposed model applied at two different region with two different climatic conditions, Rasht city located north part of Iran and Johor Bahru City, Johor, Malaysia using maximum and minimum daily temperature collected from 1975 to 2005. The result showed that the ENN outperformed the classical MLP-ANN method and successfully predict daily ETo utilizing maximum and minimum temperature only with satisfactory level of accuracy. In addition, the proposed model could achieve accuracy level better than the traditional competitor methods for ETo. © 2014 Springer Science+Business Media Dordrecht.

Yusuf N.N.A.N.,National University of Malaysia | Yusuf N.N.A.N.,University of Malaysia, Terengganu | Kamarudin S.K.,National University of Malaysia
Energy Conversion and Management | Year: 2013

This paper presents the conceptual design and economic evaluation of a production of methyl esters (biodiesel) from Jatropha curcas oil (JCO) via a supercritical methanol process with glycerol as a by-product. The process consists of four major units: transesterification (PFR), methanol recovery (FT) and (DC1), recovery of glycerol (DEC), and biodiesel purification (DC2). The material and heat balance are also presented here. A biodiesel production of 40,000 tonnes-yr-1 is taken as case study. Biodiesel obtained from supercritical transesterification with Jatropha curcas oil as feedstock resulting in high purity methyl esters (99.96%) with almost pure glycerol (96.49%) obtained as by-product. The biodiesel can be sold at USD 0.78 kg -1, while the manufacturing and capital investment costs are in the range of USD 25.39 million-year-1 and USD 9.41 million year -1, respectively. This study proved that biodiesel from JCO is the least expensive with purities comparable to those found in other studies. © 2013 Published by Elsevier Ltd.

Su Y.-F.,National Science and Technology Center for Disaster Reduction | Foody G.M.,University of Nottingham | Muad A.M.,National University of Malaysia | Cheng K.-S.,National Taiwan University
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing | Year: 2012

Combining super-resolution techniques can increase the accuracy with which the shape of objects may be characterised from imagery. This is illustrated with two approaches to combining the contouring and pixel swapping methods of super-resolution mapping for binary classification applications. In both approaches, the output of the pixel swapping method is softened to allow a contour of equal class membership to be fitted to it to represent the inter-class boundary. The accuracy of super-resolution mapping with the individual and combined techniques is explored, including an assessment of the effect of variation in the number of neighbors and zoom factor on pixel swapping based analyses. When combined, the error with which objects of varying shape were represented was typically greatly reduced relative to that observed from the application of the methods individually. For example, the root mean square error in mapping the boundary of an aeroplane represented in relatively fine spatial resolution imagery decreased from 14.41 m with contouring and 4.35 m with pixel swapping to 3.07 m when the approaches were combined. © 2008-2012 IEEE.

Su Y.-F.,National Science and Technology Center for Disaster Reduction | Foody G.M.,University of Nottingham | Muad A.M.,National University of Malaysia | Cheng K.-S.,National Taiwan University
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing | Year: 2012

The mixed pixel problem may be reduced through the use of a soft image classification and super-resolution mapping analyses. Here, the positive attributes of two popular super-resolution mapping methods, based on contouring and the Hopfield neural network, are combined. For a binary classification scenario, the method is based on fitting a contour of equal class membership to a pre-final output of a standard Hopfield neural network. Analyses of simulated and real image data sets show that the proposed method is more accurate than the standard contouring and Hopfield neural network based methods, with error typically reduced by a factor of two or more. The sensitivity of the Hopfield neural network based approaches to the setting of a gain function is also explored. © 2008-2012 IEEE.

Yaakob Z.,National University of Malaysia | Mohammad M.,National University of Malaysia | Alherbawi M.,International Islamic University Malaysia | Alam Z.,International Islamic University Malaysia | Sopian K.,National University of Malaysia
Renewable and Sustainable Energy Reviews | Year: 2013

In recent years, biodiesel has attracted significant attention from researchers, governments, and industries as a renewable, biodegradable, and non-toxic fuel. However, several feedstocks have been proven impractical or infeasible because of their extremely high cost due to their usage primarily as food resources. Waste cooking oil (WCO) is considered the most promising biodiesel feedstock despite its drawbacks, such as its high free fatty acid (FFA) and water contents. This review paper provides a comprehensive overview of the pre-treatment and the usage of WCO for the production of biodiesel using several methods, different types of reactors, and various types and amounts of alcohol and catalysts. The most common process in the production of biodiesel is transesterification, and using a methanol-ethanol mixture will combine the advantages of both alcohols in biodiesel production. In addition, this paper highlights the purification and analysis of the produced biodiesel, operating parameters that highly affect the biodiesel yield, and several economic studies. This review suggests that WCO is a promising feedstock in biodiesel production. © 2012 Elsevier Ltd. All rights reserved.

Azim R.,Chittagong University | Azim R.,National University of Malaysia | Islam M.T.,National University of Malaysia | Mobashsher A.T.,Queensland University of Technology
IEEE Antennas and Wireless Propagation Letters | Year: 2014

A microstrip line-fed planar antenna with dual notched bands is designed and prototyped for ultrawideband (UWB) communication applications. The dual band-notch characteristic is achieved by etching a single tri-arm resonator below the patch. The simulated and experimental results show that the designed antenna has achieved a wide bandwidth (return loss -10 dB) ranging from 2.98 to 10.76 GHz with two notched bands operating at 3.5 and 5.5 GHz. The proposed antenna uses only one simple filter element to create and control dual notched bands, which give it advantages over the recently proposed band-notch antennas. In addition, the designed antenna achieved a good gain and exhibits omnidirectional radiation patterns except at notched bands, which make it a suitable candidate for UWB applications. © 2002-2011 IEEE.

Kazem H.A.,Sohar University | Khatib T.,Sohar University | Sopian K.,National University of Malaysia
Energy and Buildings | Year: 2013

This paper presents a method for optimal sizing of a standalone PV system for remote areas in Sohar, Oman. PV array tilt angle as well as the size of the system's energy sources are designed optimally for better performance and lower energy cost. Numerical methods for optimization of the PV module tilt angle, PV array size and storage battery capacity are implemented using MATLAB and hourly meteorological data and load demand. The results show that for Sohar zone the tilt angle of a PV array must be adjusted twice a year. The PV array must be slanted at 49° in the period of 21/09-21/03 (n = 255-81), while it must be horizontal (tilt angle is zero) in the period of 21/03-21/09 (n = 81-255). This adjustment practice gains the energy collected by a PV array by 20.6%. As for the PV system size, the results show that the sizing ration of the PV array for Oman is 1.33 while the sizing ratio for battery is 1.6. However the cost of the energy generated by the proposed system is 0.196 USD/kWh. © 2013 Elsevier B.V.

Yusuf N.N.A.N.,National University of Malaysia | Yusuf N.N.A.N.,University of Malaysia, Terengganu | Kamarudin S.K.,National University of Malaysia | Yaakob Z.,National University of Malaysia
Biofuels, Bioproducts and Biorefining | Year: 2012

Jatropha curcas oil (JCO) is considered a future feedstock for biodiesel production because it is easily grown in harsh environments and is a non-edible crop that is not in demand as a food source. Three basic methods are used to produce biodiesel from oils/fats, namely the base-catalyzed transesterification, acid-catalyzed transesterification, and enzymatic catalysis. However, heterogeneous transesterification using a solid catalyst rather than a liquid acid or base catalyst is a more environmentally responsible way to utilize crude Jatropha oil for biodiesel production. The use of a heterogeneous catalyst also avoids neutralization and washing steps, thereby leading to a simpler and more efficient process. This paper presents an overview of the production of biodiesel from Jatropha Curcas Linnaeus (JCL) using a heterogeneous catalyst. This review also includes the current economic trend of biofuel production particularly on the production of biodiesel. Different types of conventional and advanced methods like ultrasound, microwave, membrane reactor, supercritical methanol, etc., using several types of heterogeneous catalysts like calcium oxide (CaO), sulfanated zirconia alumina (SZA) and others in the JCO biodiesel transesterification process are discussed in detail. The system design of the transesterification process via process simulation and optimization are also presented. Finally, the persistent challenges facing this process are discussed. © 2012 Society of Chemical Industry and John Wiley & Sons, Ltd.

Suherman H.,National University of Malaysia | Suherman H.,Bung Hatta University | Sulong A.B.,National University of Malaysia | Sahari J.,National University of Malaysia
Ceramics International | Year: 2013

The main challenges for commercialization of a single-filler graphite (G) polymer-matrix composite as bipolar plates are its low electrical conductivity and flexural strength. The minimum requirements set by the US Department of Energy (DOE) are the electrical conductivity and flexural strength to be greater than 100 S/cm and 25 MPa, respectively. In this study, the electrical conductivity of a G/epoxy (EP) composite (single filler) is only 50 S/cm (in-plane conductivity) at 80 wt% G. However, flexural strength is greater than 25 MPa. Using carbon nanotubes (CNTs) as the second filler at a concentration of 5 wt% in a CNTs/G/EP nanocomposite resulted in the in-plane and through-plane electrical conductivity and flexural strength being 180 S/cm, 75 S/cm, and 45 MPa, respectively. The density of the CNTs/G/EP nanocomposite is also less than that of G/EP composite, which demonstrates that a total weight reduction is achievable. © 2012 Elsevier Ltd and Techna Group S.r.l.

Idris R.,University of Malaysia, Terengganu | Hashim I.,National University of Malaysia
International Communications in Heat and Mass Transfer | Year: 2010

This study investigated the instability of Bénard-Marangoni convection in a horizontal layer of ferrofluid under the influence of a linear feedback control and cubic temperature profile. A linear stability analysis was performed. A single-term Galerkin technique was used to obtain the critical Marangoni number and critical Rayleigh number. The possibility of delaying the onset of convection by the application of linear feedback control is demonstrated. © 2009 Elsevier Ltd.

Kazem H.A.,Sohar University | Khatib T.,Klagenfurt University | Sopian K.,National University of Malaysia | Elmenreich W.,Klagenfurt University
Energy and Buildings | Year: 2014

This paper presents a design and evaluation practice of a grid-connected photovoltaic system installed in Sohar, Oman. Hourly solar radiation and ambient temperature data for one year time are utilized. The designed system is implemented practically and tested for six months to check its productivity and feasibility. The system is evaluated using three technical criteria which are capacity, yield and performance factors. In addition, system's feasibility is evaluated in terms of cost of energy and payback period. The results show that the capacity and the yield factors for the proposed system are 21% and 1875 kW h/kW p/year respectively. In addition, the performance factor of the proposed system is 84.6%. In the meanwhile, the cost of the energy generated and the payback period of the proposed system are 0.045 USD/kW h and 11 years, respectively. This study contains valuable experiment data for those who are interested in photovoltaic system in Oman and nearby desertic zones. © 2014 Elsevier B.V.

Azim R.,National University of Malaysia | Islam M.T.,National University of Malaysia | Mobashsher A.T.,Queensland University of Technology
IEEE Antennas and Wireless Propagation Letters | Year: 2013

In this letter, a planar slot antenna with dual-band-notch characteristics is proposed for ultrawideband application. The basic antenna comprises a rectangular tuning stub and a ground plane with a tapered-shape slot. To create a notched band for WiMAX, one angle-shaped parasitic slit is etched out along with the tuning stub, while for WLAN, two symmetrical parasitic slits are placed inside the slot of the ground plane. By properly adjusting the size and location of the parasitic slits, it is found that the proposed antenna can achieve ultrawide operating band with dual-notched band without altering the overall antenna size. These notched bands will help to mitigate the possible interference between UWB and these narrow bands. © 2013 IEEE.

Azim R.,National University of Malaysia | Mobashsher A.T.,Queensland University of Technology | Islam M.T.,National University of Malaysia
Electronics Letters | Year: 2013

A slot antenna with a notched band at 5.5 GHz is proposed for UWB applications. The basic UWB antenna comprises of a rectangular radiating patch and a ground plane with a tapered shape slot and printed on 1.6 mm-thick FR4 dielectric substrate. To realise a notch band, two symmetrical slits are etched on the slot of the ground plane. Experimental results show that the proposed antenna exhibits wideband performance from 3.08 to more than 11 GHz with a notched frequency band centred at 5.5 GHz which can effectively mitigate the interference between the WLAN and UWB systems. It is also confirmed from the measurements that the insertion of slits does not affect the antenna performance, except at the notched frequency band. © The Institution of Engineering and Technology 2013.

Zhou T.,University of Western Australia | Razali S.F.M.,National University of Malaysia | Hao Z.,Shanghai Maritime University | Cheng L.,University of Western Australia
Journal of Fluids and Structures | Year: 2011

While the effect of helical strakes on suppression of Vortex-Induced Vibrations (VIV) has been studied extensively, the mechanism of VIV mitigation using helical strakes is much less well documented in the literature. In the present study, a rigid circular cylinder of diameter d=80. mm attached with three-strand helical strakes of dimensions of 10. d in pitch and 0.12. d in height was tested in a wind tunnel. It was found that the helical strakes can reduce VIV by about 98%. Unlike the bare cylinder, which experiences lock-in over the reduced velocity in the range of 5-8.5, the straked cylinder does not show any lock-in region. In exploring the mechanism of VIV reduction by helical strakes, measurements in stationary bare and straked cylinder wakes using both a single X-probe at four different Reynolds numbers, i.e. Re=10. 240, 20. 430, 30. 610 and 40. 800, and two X-probes with variable separations in the spanwise direction at Re=20. 430 were conducted. It was found that vortices shed from the straked cylinder are weakened significantly. The dominate frequency varies by about 30% over the range of x/. d=10-40 in the streamwise direction while that differs by about 37.2% of the averaged peak frequency over a length of 3.125. d in the spanwise direction. The latter is supported by the phase difference between the velocity signals measured at two locations separated in the spanwise direction. The correlation length of the vortex structures in the bare cylinder wake is much larger than that obtained in the straked cylinder wake. As a result, the straked cylinder wake agrees more closely with isotropy than the bare cylinder wake. Flow visualization on the plane perpendicular to the cylinder axis at Reynolds number of about 300 reveals small-scale vortices in the shear layers of the straked cylinder wake. However, these vortices do not roll up and interact with each other to form the well-organized Karman-type vortices. Flow visualization on the plane parallel to the cylinder axis shows vortex dislocation and swirling flow, which should be responsible for the variations of the peak frequency in the streamwise as well as spanwise directions. © 2011 Elsevier Ltd.

Yahaya J.H.,National University of Malaysia | Deraman A.,University of Malaysia, Terengganu
International Journal of Advancements in Computing Technology | Year: 2012

Software products do exhibit a behaviour that closely resembles human ageing. Similar to people, we believe that software too gets old and as naturally we can't prevent ageing, but we can understand its causes and take steps to limit its effects. As a logical product, software is not getting older physically, but in some circumstances the relevance and importance of it is getting lesser and lesser to its environment. Thus, this is the phenomena of getting older. Unlike human ageing, software ageing function can be formulated by relevant, failure, cost, technology and etc. Identifying and detecting these factors will help to rejuvenate the software and delays the ageing. The previous works motivated and led us to the development of software anti-ageing model and its related areas such as ageing factors and rejuvenation index. In this paper, the background research in software quality and certification are discussed and explored which then move on to the ageing issues and identified ageing factors.

Abualkishik A.,University Tenaga Malaysia | Omar K.,National University of Malaysia
International Conference on Research and Innovation in Information Systems, ICRIIS | Year: 2013

The Holy Quran is the central religious verbal text of Islam. Muslim people are expected to read, understand, and apply teachings of the Holy Quran. Holy Quran was translated to Braille code as a normal Arabic text without included its reciting rules. This, obviously, mean that the users of this translation is not able to recite the Quran the right way. Through this work, Quran Braille Translator (QBT) is introduced to be as specific translator to translate Quran verses text into Braille code. QBT is using Extended Finite State Machine (EFSM) technique for detecting Quran Reciting Rules (QRR) from the Quran text and Markov Algorithm (MA) for translating the detected QRR and Quran text into the matched Braille code. The data entries for QBT are Arabic letters and diacritics. Detecting and translating measurement processes were done for translated text. The Holy Quran is the central religious verbal text of Islam. Muslim people are expected to read, understand, and apply teachings of the Holy Quran. Holy Quran was translated to Braille code as a normal Arabic text without included its reciting rules. This, obviously, mean that the users of this translation is not able to recite the Quran the right way. Through this work, Quran Braille Framework is introduced to be as specific Framework to translate Quran verses text and its reciting rules into Braille code. User Acceptance Technology had done for QBT and the results were positive. © 2013 IEEE.

Azim R.,National University of Malaysia | Islam M.T.,National University of Malaysia | Mandeep J.S.,National University of Malaysia | Mobashsher A.T.,Queensland University of Technology
Journal of Electromagnetic Waves and Applications | Year: 2012

A compact planar monopole ultra-wideband (UWB) antenna with dual band-notched characteristics is proposed in order to minimize the interference between UWB systems and existing world interoperability for microwave access and wireless local area network operating bands. The antenna has a microstrip line-fed circular ring radiator with one etched partial concentric annular slot and one semi-circular slot. Two rectangular slots are also etched to connect the slots to the outer and inner periphery of the circular ring radiator. The desired dual band-notched UWB operation can be obtained by choosing the size and location of the etched slots. Experimental results show that with a compact size of 24 mm × 26 mm the proposed antenna achieves a wide impedance bandwidth from 2.79 to more than 11 GHz with two frequency notched bands of 3.3-3.8 and 5.1-6 GHz for WiMAX and WLAN, respectively. Moreover, the antenna exhibits stable radiation characteristics and a good time domain behavior which makes it suitable for being used in the future UWB applications. © 2012 Taylor & Francis.

Agency: GTR | Branch: NERC | Program: | Phase: Research Grant | Award Amount: 1.30M | Year: 2013

Anthropogenic disturbance and land-use change in the tropics is leading to irrevocable changes in biodiversity and substantial shifts in ecosystem biogeochemistry. Yet, we still have a poor understanding of how human-driven changes in biodiversity feed back to alter biogeochemical processes. This knowledge gap substantially restricts our ability to model and predict the response of tropical ecosystems to current and future environmental change. There are a number of critical challenges to our understanding of how changes in biodiversity may alter ecosystem processes in the tropics; namely: (i) how the high taxonomic diversity of the tropics is linked to ecosystem functioning, (ii) how changes in the interactions among trophic levels and taxonomic groups following disturbance impacts upon functional diversity and biogeochemistry, and (iii) how plot-level measurements can be used to scale to whole landscapes. We have formed a consortium to address these critical challenges to launch a large-scale, replicated, and fully integrated study that brings together a multi-disciplinary team with the skills and expertise to study the necessary taxonomic and trophic groups, different biogeochemical processes, and the complex interactions amongst them. To understand and quantify the effects of land-use change on the activity of focal biodiversity groups and how this impacts biogeochemistry, we will: (i) analyse pre-existing data on distributions of focal biodiversity groups; (ii) sample the landscape-scale treatments at the Stability of Altered Forest Ecosystems (SAFE) Project site (treatments include forest degradation, fragmentation, oil palm conversion) and key auxiliary sites (Maliau Basin - old growth on infertile soils, Lambir Hills - old growth on fertile soils, Sabah Biodiversity Experiment - rehabilitated forest, INFAPRO-FACE - rehabilitated forest); and (iii) implement new experiments that manipulate key components of biodiversity and pathways of belowground carbon flux. The manipulations will focus on trees and lianas, mycorrhizal fungi, termites and ants, because these organisms are the likely agents of change for biogeochemical cycling in human-modified tropical forests. We will use a combination of cutting-edge techniques to test how these target groups of organisms interact each other to affect biogeochemical cycling. We will additionally collate and analyse archived data on other taxa, including vertebrates of conservation concern. The key unifying concept is the recognition that so-called functional traits play a key role in linking taxonomic diversity to ecosystem function. We will focus on identifying key functional traits associated with plants, and how they vary in abundance along the disturbance gradient at SAFE. In particular, we propose that leaf functional traits (e.g. physical and chemical recalcitrance, nitrogen content, etc.) play a pivotal role in determining key ecosystem processes and also strongly influence atmospheric composition. Critically, cutting-edge airborne remote sensing techniques suggest it is possible to map leaf functional traits, chemistry and physiology at landscape-scales, and so we will use these novel airborne methods to quantify landscape-scale patterns of forest degradation, canopy structure, biogeochemical cycling and tree distributions. Process-based mathematical models will then be linked to the remote sensing imagery and ground-based measurements of functional diversity and biogeochemical cycling to upscale our findings over disturbance gradients.

Li Z.,First Institute of Oceanography | Yu W.,First Institute of Oceanography | Li T.,University of Hawaii at Manoa | Murty V.S.N.,National Institute of Oceanography of India | Tangang F.,National University of Malaysia
Journal of Climate | Year: 2013

The annual cycle of tropical cyclone (TC) frequency over the Bay of Bengal (BoB) exhibits a notable bimodal character, different from a single peak in other basins. The causes of this peculiar feature were investigated through the diagnosis of a genesis potential index (GPI) with the use of the NCEP Reanalysis I dataset during the period 1981-2009. A methodology was developed to quantitatively assess the relative contributions of four environmental parameters. Different from a conventional view that the seasonal change of vertical shear causes the bimodal feature, it was found that the strengthened vertical shear alone from boreal spring to summer cannot overcome the relative humidity effect. It is the combined effect of vertical shear, vorticity, and SST that leads to the GPI minimum in boreal summer. It is noted that TC frequency in October-November is higher than that in April-May, which is primarily attributed to the difference of mean relative humidity between the two periods. In contrast, more supercyclones (category 4 or above) occur in April-May than in October-November. It is argued that greater ocean heat content, the first branch of northward-propagating intraseasonal oscillations (ISOs) associated with the monsoon onset over the BoB, and stronger ISO intensity in April-May are favorable environmental conditions for cyclone intensification. © 2013 American Meteorological Society.

Reis A.,Aston University | Rudnitskaya A.,University of Aveiro | Blackburn G.J.,University of Strathclyde | Fauzi N.M.,National University of Malaysia | And 2 more authors.
Journal of Lipid Research | Year: 2013

Lipidome profile of fluids and tissues is a growing field as the role of lipids as signaling molecules is increasingly understood, relying on an effective and representative extraction of the lipids present. A number of solvent systems suitable for lipid extraction are commonly in use, though no comprehensive investigation of their effectiveness across multiple lipid classes has been carried out. To address this, human LDL from normolipidemic volunteers was used to evaluate five different solvent extraction protocols [Folch, Bligh and Dyer, acidified Bligh and Dyer, methanol (MeOH)-tert-butyl methyl ether (TBME), and hexane-isopropanol] and the extracted lipids were analyzed by LC-MS in a high-resolution instrument equipped with polarity switching. Overall, more than 350 different lipid species from 19 lipid subclasses were identified. Solvent composition had a small effect on the extraction of predominant lipid classes (triacylglycerides, cholesterol esters, and phosphatidylcholines). In contrast, extraction of less abundant lipids (phosphatidylinositols, lyso-lipids, ceramides, and cholesterol sulfates) was greatly influenced by the solvent system used. Overall, the Folch method was most effective for the extraction of a broad range of lipid classes in LDL, although the hexane-isopropanol method was best for apolar lipids and the MeOH-TBME method was suitable for lactosyl ceramides. Copyright © 2013 by the American Society for Biochemistry and Molecular Biology, Inc.

Ashtari A.H.,National University of Malaysia | Nordin M.J.,National University of Malaysia | Fathy M.,Iran University of Science and Technology
IEEE Transactions on Intelligent Transportation Systems | Year: 2014

In this paper, an Iranian vehicle license plate recognition system based on a new localization approach, which is modified to reflect the local context, is proposed, along with a hybrid classifier that recognizes license plate characters. The method presented here is based on a modified template-matching technique by the analysis of target color pixels to detect the location of a vehicle's license plate. A modified strip search enables localization of the standard color-geometric template utilized in Iran and several European countries. This approach uses periodic strip search to find the hue of each pixel on demand. In addition, when a group of target pixels is detected, it is analyzed to verify that its shape and aspect ratio match those of the standard license plate. In addition to being scale and rotation invariant, this method avoids time-consuming image algorithms and transformations for the whole image pixels, such as resizing and Hough, Fourier, and wavelet transforms, thereby cutting down the detection response time. License plate characters are recognized by a hybrid classifier that comprises a decision tree and a support vector machine with a homogeneous fifth-degree polynomial kernel. The performance detection rate and the overall system performance achieved are 96% and 94%, respectively. © 2014 IEEE.

Ganasegeran K.,Management and Science University | Renganathan P.,Tengku Ampuan Rahimah Hospital HTAR | Manaf R.A.,National University of Malaysia | Al-Dubai S.A.R.,International Medical University
BMJ Open | Year: 2014

Objective: To determine the prevalence and factors associated with anxiety and depression among type 2 diabetes outpatients in Malaysia. Design: Descriptive, cross-sectional single-centre study with universal sampling of all patients with type 2 diabetes. Setting: Endocrinology clinic of medical outpatient department in a Malaysian public hospital. Participants: All 169 patients with type 2 diabetes (men, n=99; women, n=70) aged between 18 and 90 years who acquired follow-up treatment from the endocrinology clinic in the month of September 2013. Main outcome measures: The validated Hospital Anxiety and Depression Scale (HADS), sociodemographic characteristics and clinical health information from patient records. Results: Of the total 169 patients surveyed, anxiety and depression were found in 53 (31.4%) and 68 (40.3%), respectively. In multivariate analysis, age, ethnicity and ischaemic heart disease were significantly associated with anxiety, while age, ethnicity and monthly household income were significantly associated with depression. Conclusions: Sociodemographics and clinical health factors were important correlates of anxiety and depression among patients with diabetes. Integrated psychological and medical care to boost self-determination and confidence in the management of diabetes would catalyse optimal health outcomes among patients with diabetes.

Ahmad M.Z.,University Malaysia Perlis | Hasan M.K.,National University of Malaysia | De Baets B.,Ghent University
Information Sciences | Year: 2013

In this paper, we study analytical and numerical solutions of fuzzy differential equations based on the extension principle. For linear fuzzy differential equations, we state some results on the behaviour of the solutions and study their relationship with the generalised Hukuhara derivative. In order to approximate the solutions of linear and non-linear fuzzy differential equations, we propose a new fuzzification of the classical Euler method and then incorporate an unconstrained optimisation technique. This combination offers a powerful tool to tackle uncertainty in any numerical method. An efficient computational algorithm is also provided to guarantee the convexity of fuzzy solutions on the time domain. Several illustrative examples are given. © 2013 Elsevier Inc. All rights reserved.

Abeer M.M.,National University of Malaysia | Mohd Amin M.C.I.,National University of Malaysia | Martin C.,University of Wolverhampton
Journal of Pharmacy and Pharmacology | Year: 2014

Objectives The field of pharmaceutical technology is expanding rapidly because of the increasing number of drug delivery options. Successful drug delivery is influenced by multiple factors, one of which is the appropriate identification of materials for research and engineering of new drug delivery systems. Bacterial cellulose (BC) is one such biopolymer that fulfils the criteria for consideration as a drug delivery material. Key findings BC showed versatility in terms of its potential for in-situ modulation, chemical modification after synthesis and application in the biomedical field, thus expanding the current, more limited view of BC and facilitating the investigation of its potential for application in drug delivery. Summary Cellulose, which is widely available in nature, has numerous applications. One of the applications is that of BC in the pharmaceutical and biomedical fields, where it has been primarily applied for transdermal formulations to improve clinical outcomes. This review takes a multidisciplinary approach to consideration of the feasibility and potential benefits of BC in the development of other drug delivery systems for various routes of administration. © 2014 Royal Pharmaceutical Society.

Schacher F.H.,Friedrich - Schiller University of Jena | Elbert J.,University of Bristol | Patra S.K.,University of Bristol | Mohd Yusoff S.F.,National University of Malaysia | And 2 more authors.
Chemistry - A European Journal | Year: 2012

We demonstrate the synthesis and characterization of star-shaped crystalline-coil block copolymers with four arms consisting of an inner block of poly(ethylene oxide) and an outer semicrystalline compartment of poly(ferrocenyldimethylsilane), [PEO 50-b-PFDMS 35] 4. The materials were synthesized by transition-metal-catalyzed ring-opening polymerization of dimethylsila[1]ferrocenophane in the presence of silane-functionalized four-arm PEO stars as macroinitiators and they exhibited a moderate polydispersity (PDI≃1.4). Self-assembly in mixtures of THF and different alcohols as selective solvents for the PEO block resulted in the formation of semicrystalline vesicles (ethanol, 1-butanol) or large, rather ill-defined, spherical structures (methanol). Further, both the rate of addition of the selective co-solvent and the overall solvent/non-solvent ratio drastically affected the size and stability of the self-assembled particles. We could also show that a photoacid generator, as a model for an active substance, can be encapsulated and the UV-induced generation of HCl resulted in a straightforward degradation of the organometallic vesicles. Four arms to the wall: The synthesis, characterization and self-assembly of star-shaped crystalline-coil block copolymers with four arms (see figure), consisting of an inner block of poly(ethylene oxide) and an outer semicrystalline compartment of poly(ferrocenyldimethylsilane) [PEO 50-b-PFDMS 35] 4 is reported. Depending on the conditions, responsive organometallic vesicles with a crystalline wall or large compound micelles are formed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pourebrahim S.,Arak University | Hadipour M.,Arak University | Bin Mokhtar M.,National University of Malaysia
Landscape and Urban Planning | Year: 2011

A systematic approach was used to develop an integrated plan to determine the optimal land use suitability for future sustainable development in the coastal area of the Kuala Langat District, Selangor, Malaysia based on different planning scenarios. Use of the multi criteria evaluation (MCE) especially Analytic Network Process (ANP) allowed for the integration of expert opinion on social, economic and environmental criteria within the planning framework and provided an efficient spatial approach for coastal land use development. Scenario analysis resulted in a series of suitability maps for conservation, tourism, residential and industrial development. Three scenarios addressing economic and social development, environmental conservation and sustainable development were defined and evaluated. Four land uses were considered: namely, residential, conservation, tourism and industry. By evaluating various scenarios, existing plans and guidelines, land availability and current uses, the optimum suitability for coastal land uses towards sustainable development was proposed. However, only one optimal land suitability map was proposed for the sustainable development scenario. The spatial scenario planning framework developed in this research is an example of an effective, integrated decision-making framework. The methodology is brief, a set of guidelines and recommendations is included for organising, and expressing the complexities found in oastal area. To date, there is no published application of an ANP in spatial planning for coastal land uses or for related fields. It is hoped that this approach can be employed for land use suitability assessments at both the local and the structure-plan level. © 2011 Elsevier B.V.

Ahmad K.,National University of Malaysia | Yan Y.,Santa Clara University | Bless D.,University of Wisconsin - Madison
Journal of Voice | Year: 2012

Objectives/Hypothesis: A high proportion of the geriatric population suffers from presbylaryngis and presbyphonia; however, our knowledge of vibratory patterns in this population is almost nonexistent. In this study, we investigate the vocal fold vibratory patterns of healthy elderly females to determine which features or combination of them could best describe the geriatric voices. Study Design: Cross-sectional study with 20 elderly healthy females with no history of voice problems. Methods: Hilbert transformed glottal area waveforms (GAWs) from serial high-speed digital imaging of sustained phonation are used to provide quantitative measures of glottal vibratory characteristics and perturbations; open quotient, jitter, and shimmer. Nyquist plots provide interpretable patterns to portray the vibratory characteristics as clear, pressed, breathy, and atypical patterns. Results: The GAW from most elderly speakers (50%) showed vibratory characteristics associated with a more pressed voice and higher glottal perturbation values: their Nyquist plot patterns show wide scatterings around the rim of the plot reflecting a much-reduced ability in sustaining vibratory oscillation; these were distinct differences from previously reported data on younger speakers. Qualitative examination revealed more anteriorly placed glottal gaps in the geriatric females. Conclusion: These findings have important implications in understanding voice production in the geriatric population and in helping to establish normal perturbation references among female speakers across age. © 2012 The Voice Foundation.

Sheltami R.M.,National University of Malaysia | Sheltami R.M.,University of Benghazi | Abdullah I.,National University of Malaysia | Ahmad I.,National University of Malaysia | And 2 more authors.
Carbohydrate Polymers | Year: 2012

Cellulose was extracted from mengkuang leaves (pandanus tectorius) by carrying out alkali and bleaching treatments. Cellulose nanocrystals were isolated from extracted cellulose with concentrated sulphuric acid. The chemical composition of mengkuang leaves was determined at different stages of treatment. Structural analysis was carried out by Fourier transform infrared spectroscopy and X-ray diffraction. Field emission scanning electron microscopy and transmission electron microscopy were used to investigate the morphology of the isolated cellulose and cellulose nanocrystal, respectively. The thermal stability of mengkuang leaves at different stages of treatment was investigated by thermogravimetric analysis. The results indicated that the hemicellulose and lignin were removed extensively from the extracted cellulose. The isolated cellulose and cellulose nanocrystals were found to have diameters in the range 5-80 μm and 5-25 nm, respectively. The thermal stability of the leaves was found to increase at various purification stages when compared to the raw material. © 2012 Elsevier Ltd. All rights reserved.

Mousavi S.M.,University of Malaya | Hajipour V.,Islamic Azad University at Qazvin | Niaki S.T.A.,Sharif University of Technology | Aalikar N.,National University of Malaysia
International Journal of Advanced Manufacturing Technology | Year: 2014

In this paper, a seasonal multi-product multi-period inventory control problem is modeled in which the inventory costs are obtained under inflation and all-unit discount policy. Furthermore, the products are delivered in boxes of known number of items, and in case of shortage, a fraction of demand is considered backorder and a fraction lost sale. Besides, the total storage space and total available budget are limited. The objective is to find the optimal number of boxes of the products in different periods to minimize the total inventory cost (including ordering, holding, shortage, and purchasing costs). Since the integer nonlinear model of the problem is hard to solve using exact methods, a particle swarm optimization (PSO) algorithm is proposed to find a near-optimal solution. Since there is no bench mark available in the literature to justify and validate the results, a genetic algorithm is presented as well. In order to compare the performances of the two algorithms in terms of the fitness function and the required CPU time, they are first tuned using the Taguchi approach, in which a metric called "smaller is better" is used to model the response variable. Then, some numerical examples are provided to demonstrate the application and to validate the results obtained. The results show that, while both algorithms have statistically similar performances, PSO tends to be the better algorithm in almost all problems. © 2013 Springer-Verlag London.

Bella F.,Center for Space Human Robotics Polito | Bella F.,Polytechnic University of Turin | Imperiyka M.,University of Benghazi | Ahmad A.,National University of Malaysia
Journal of Photochemistry and Photobiology A: Chemistry | Year: 2014

Dye-sensitized solar cells are increasingly establishing themselves as third generation photovoltaic technology which can be manufactured with easily available materials and low-cost processes. In this context, the replacement of the liquid electrolyte with quasi-linear polymer electrolyte membranes is here proposed, with the aim of increasing the durability of the device. The membranes are photochemically produced starting from two methacrylic monomers, by means of a process that does not involve the use of solvents and catalysts. In order to ensure handling and durability, the membranes are partially crosslinked with a tunable opening of the epoxy ring of one of the two monomers, thus binding together different polymer chains and allowing an effective entrapment of the redox mediator within the network. The experimental conditions are investigated and optimized by means of a multivariate chemometric approach, and the characterization of materials and devices is presented. Quasi-solid cells able to maintain efficiency up to 4% after 500 h of accelerated ageing are successfully fabricated. © 2014 Elsevier B.V.

Samimi P.,National University of Malaysia | Teimouri Y.,Islamic Azad University at Qazvin | Mukhtar M.,National University of Malaysia
Information Sciences | Year: 2014

Users and providers have different requirements and objectives in an investment market. Users will pay the lowest price possible with certain guaranteed levels of service at a minimum and providers would follow the strategy of achieving the highest return on their investment. Designing an optimal market-based resource allocation that considers the benefits for both the users and providers is a fundamental criterion of resource management in distributed systems, especially in cloud computing services. Most of the current market-based resource allocation models are biased in favor of the provider over the buyer in an unregulated trading environment. In this study, the problem was addressed by proposing a new market model called the Combinatorial Double Auction Resource Allocation (CDARA), which is applicable in cloud computing environments. The CDARA was prototyped and simulated using CloudSim, a Java-based simulator for simulating cloud computing environments, to evaluate its efficiency from an economic perspective. The results proved that the combinatorial double auction-based resource allocation model is an appropriate market-based model for cloud computing because it allows double-sided competition and bidding on an unrestricted number of items, which causes it to be economically efficient. Furthermore, the proposed model is incentive-compatible, which motivates the participants to reveal their true valuation during bidding. © 2014 Elsevier Inc. All rights reserved.

Arifin N.M.,University Putra Malaysia | Nazar R.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
Meccanica | Year: 2011

In this paper, a non-isobaric Marangoni boundary layer flow that can be formed along the interface of immiscible nanofluids in surface driven flows due to an imposed temperature gradient, is considered. The solution is determined using a similarity solution for both the momentum and energy equations and assuming developing boundary layer flow along the interface of the immiscible nanofluids. The resulting system of nonlinear ordinary differential equations is solved numerically using the shooting method along with the Runge-Kutta-Fehlberg method. Numerical results are obtained for the interface velocity, the surface temperature gradient as well as the velocity and temperature profiles for some values of the governing parameters, namely the nanoparticle volume fraction ω (0 ≤ ω ≤ 0.2) and the constant exponent β. Three different types of nanoparticles, namely Cu, Al 2O3 and TiO2 are considered by using water-based fluid with Prandtl number Pr = 6.2. It was found that nanoparticles with low thermal conductivity, TiO2, have better enhancement on heat transfer compared to Al2O3 and Cu. The results also indicate that dual solutions exist when β <0.5. The paper complements also the work by Golia and Viviani (Meccanica 21:200-204, 1986) concerning the dual solutions in the case of adverse pressure gradient. © 2010 Springer Science+Business Media B.V.

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

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

Hejazi N.,National University of Malaysia | Rajikan R.,National University of Malaysia | Kwok Choong C.L.,Hospital Sungai Buloh | Sahar S.,National University of Malaysia
BMC Public Health | Year: 2013

Background: In the current two decades, dyslipidemia and increased blood glucose as metabolic abnormalities are the most common health threats with a high incidence among HIV/AIDS patients on antiretroviral (ARV) treatment. Scientific investigations and reports on lipid and glucose disorders among HIV infected communities are inadequate especially in those developing such as Malaysia. This cross-sectional survey was mainly aimed to evaluate the prevalence of metabolic abnormalities and associated risk factors among HIV infected population patients on ARV medication. Methods. In a single reference health center in Malaysia, 2739 adult HIV positive patients on antiretroviral therapy (ART) were studied cross-sectionally using medical records. Besides demographic variables and associated health disorders, those factors which can change the lipid and glucose levels were collected. Logistic Regression was used to find the potential risk factors (p < 0.05). Results: Majority of the studied population were male (81.1%) and aged between 30-49 (68.6%). Mean CD4 count was 474.25 (cells/mm§ssup§3§esup§) while undetectable RNA viral load was common among 83.3 (%) of subjects. Among 1,583 patients with the recent blood lipid and glucose tests, increased levels of triglyceride (TG) and total cholesterol (TC) were frequently prevalent in half of the population as 59 (%) and 54.2 (%) while 28.7 (%), 35.1 (%) and 38.2 (%) had declined level of high-density lipoprotein (HDL), raised low-density lipoprotein (LDL) and fasting plasma glucose (FPG) which were less common. Dyslipidemia was common in 82.3 (%) of the subjects. Notably, medication with protease inhibitor (PI) was a potential risk for elevated triglyceride (odds ratio (OR) = 2.309, 95% confidence interval (CI) = 1.605-3.324, P = 0.001), high TC (OR = 1.561, 95% CI = 1.123-2.169, P = 0.008) and low HDL (OR = 1.449, 95% CI = 1.037-2.024, P = 0.029). As lifestyle factor, alcohol consumption results as significant risk factor for raised TG (OR = 2.653, 95% CI = 1.353-5.202, P = 0.004). Also having hepatitis raised risk of high FPG level (OR = 1.630, 95% CI = 1.197-2.220, P = 0.002) in this sample population. Conclusions: Dyslipidemia is highly common in Malaysian HIV subjects receiving ARV medication. Lifestyle modification, changing PI and switch to other ARV regimen can help in reduction of these abnormalities. Also suitable strategies and plans are necessary to prevent cardiovascular diseases in future. © 2013 Hejazi et al.; licensee BioMed Central Ltd.

Rosali H.,University Putra Malaysia | Ishak A.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
International Communications in Heat and Mass Transfer | Year: 2012

This paper presents a numerical analysis of a micropolar fluid flow towards a permeable stretching/shrinking sheet in a porous medium. The governing nonlinear partial differential equations are transformed into a system of ordinary differential equations by a similarity transformation, before being solved numerically by a finite-difference scheme known as the Keller-box method. The effects of the governing parameters on the fluid flow and heat transfer characteristics are illustrated graphically. It is found that dual solutions exist for the shrinking case, whereas for the stretching case, the solution is unique. © 2012 Elsevier Ltd.

Bachok N.,University Putra Malaysia | Ishak A.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
International Journal of Heat and Mass Transfer | Year: 2012

This paper considers the extended Blasius and Sakiadis problems in nanofluids, by considering a uniform free stream parallel to a fixed or moving flat plate, which has more practical significance. It is assumed that the plate moves in the same or opposite direction to the free stream. The resulting system of nonlinear ordinary differential equations is solved numerically for three types of nanoparticles, namely copper (Cu), alumina (Al2O 3), and titania (TiO2) in the water based fluid with Prandtl number Pr = 6.2. The effect of the solid volume fraction parameter of the nanofluids on the heat transfer characteristics is investigated. The results indicate that dual solutions exist when the plate and the free stream move in the opposite directions. © 2011 Elsevier Ltd. All rights reserved.

Bachok N.,University Putra Malaysia | Ishak A.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
International Journal of Heat and Mass Transfer | Year: 2012

The unsteady boundary layer flow of a nanofluid over a permeable stretching/shrinking sheet is theoretically studied. The governing partial differential equations are transformed into ordinary ones using a similarity transformation, before being solved numerically. The results are obtained for the skin friction coefficient, the local Nusselt number and the local Sherwood number as well as the velocity, temperature and the nanoparticle fraction profiles for some values of the governing parameters, namely, the unsteadiness parameter, the mass suction parameter, the Brownian motion parameter, the thermophoresis parameter, Prandtl number, Lewis number and the stretching/shrinking parameter. It is found that dual solutions exist for both stretching and shrinking cases. The results also indicate that both unsteadiness and mass suction widen the range of the stretching/shrinking parameter for which the solution exists. © 2011 Elsevier Ltd. All rights reserved.

Salleh M.Z.,Universiti Malaysia Pahang | Nazar R.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
Meccanica | Year: 2012

In this paper, the problem of free convection boundary layer flow on a solid sphere in a micropolar fluid with Newtonian heating, in which the heat transfer from the surface is proportional to the local surface temperature, is considered. The transformed boundary layer equations in the form of partial differential equations are solved numerically using an implicit finitedifference scheme. Numerical solutions are obtained for the local wall temperature, the local skin friction coefficient, as well as the velocity, angular velocity and temperature profiles. The features of the flow and heat transfer characteristics for different values of the material or micropolar parameter K, the Prandtl number Pr and the conjugate parameter γ are analyzed and discussed. © Springer Science+Business Media B.V. 2011.

Yacob N.A.,University Technology of MARA | Ishak A.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca | Vajravelu K.,University of Central Florida
Nanoscale Research Letters | Year: 2011

The problem of a steady boundary layer shear flow over a stretching/shrinking sheet in a nanofluid is studied numerically. The governing partial differential equations are transformed into ordinary differential equations using a similarity transformation, before being solved numerically by a Runge-Kutta-Fehlberg method with shooting technique. Two types of nanofluids, namely, Cu-water and Ag-water are used. The effects of nanoparticle volume fraction, the type of nanoparticles, the convective parameter, and the thermal conductivity on the heat transfer characteristics are discussed. It is found that the heat transfer rate at the surface increases with increasing nanoparticle volume fraction while it decreases with the convective parameter. Moreover, the heat transfer rate at the surface of Cu-water nanofluid is higher than that at the surface of Ag-water nanofluid even though the thermal conductivity of Ag is higher than that of Cu. © 2011 Yacob et al.

Bachok N.,University Putra Malaysia | Ishak A.,National University of Malaysia | Ishak A.,University of Malaya | Pop I.,Technical University of Cluj Napoca
Physica B: Condensed Matter | Year: 2011

The steady flow of an incompressible viscous fluid due to a rotating disk in a nanofluid is studied. The transformed boundary layer equations are solved numerically by a finite difference scheme, namely the Keller-box method. Numerical results for the flow and heat transfer characteristics are obtained for various values of the nanoparticle volume fraction parameter φ and suction/injection parameter h0. Two models for the effective thermal conductivity of the nanofluid, namely the MaxwellGarnett model and the Patel model, are considered. It is found that for the Patel model, the heat transfer rate at the surface increases for both suction and injection, whereas different behaviors are observed for the MaxwellGarnett model, i.e. increasing the values of φ leads to a decrease in the heat transfer rate at the surface for suction, but increases for injection. The results of this study can be used in the design of an effective cooling system for electronic components to help ensure effective and safe operational conditions. © 2011 Elsevier B.V. All rights reserved.

Bachok N.,University Putra Malaysia | Ishak A.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
Nanoscale Research Letters | Year: 2011

An analysis is carried out to study the steady two-dimensional stagnation-point flow of a nanofluid over a stretching/shrinking sheet in its own plane. The stretching/shrinking velocity and the ambient fluid velocity are assumed to vary linearly with the distance from the stagnation point. The similarity equations are solved numerically for three types of nanoparticles, namely copper, alumina, and titania in the water-based fluid with Prandtl number Pr = 6.2. The skin friction coefficient, Nusselt number, and the velocity and temperature profiles are presented graphically and discussed. Effects of the solid volume fraction ø on the fluid flow and heat transfer characteristics are thoroughly examined. Different from a stretching sheet, it is found that the solutions for a shrinking sheet are non-unique. © 2011 Bachok et al; licensee Springer.

Nazar R.,National University of Malaysia | Tham L.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca | Ingham D.B.,University of Leeds
Transport in Porous Media | Year: 2011

Steady mixed convection boundary layer flow from an isothermal horizontal circular cylinder embedded in a porous medium filled with a nanofluid has been studied for both cases of a heated and cooled cylinder. The resulting system of nonlinear partial differential equations is solved numerically using an implicit finite-difference scheme. The solutions for the flow and heat transfer characteristics are evaluated numerically for various values of the governing parameters, namely the nanoparticle volume fraction φ and the mixed convection parameter λ. Three different types of nanoparticles are considered, namely Cu, Al2O3 and TiO2. It is found that for each particular nanoparticle, as the nanoparticle volume fraction φ increases, the magnitude of the skin friction coefficient decreases, and this leads to an increase in the value of the mixed convection parameter λ which first produces no separation. On the other hand, it is also found that of all the three types of nanoparticles considered, for any fixed values of φ and λ, the nanoparticle Cu gives the largest values of the skin friction coefficient followed by TiO2 and Al2O3. Finally, it is worth mentioning that heating the cylinder (λ > 0) delays separation of the boundary layer and if the cylinder is hot enough (large values of λ > 0), then it is suppressed completely. On the other hand, cooling the cylinder (λ < 0) brings the boundary layer separation point nearer to the lower stagnation point and for a sufficiently cold cylinder (large values of λ <0) there will not be a boundary layer on the cylinder. © 2010 Springer Science+Business Media B.V.

Salleh M.Z.,Universiti Malaysia Pahang | Nazar R.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
Journal of the Taiwan Institute of Chemical Engineers | Year: 2010

The steady boundary layer flow and heat transfer over a stretching sheet with Newtonian heating in which the heat transfer from the surface is proportional to the local surface temperature, is considered in this study. The transformed governing nonlinear boundary layer equations are solved numerically by a finite-difference method. Numerical solutions are obtained for the heat transfer from the stretching sheet and the wall temperature for a large range of values of the Prandtl number Pr. The Newtonian heating is controlled by a dimensionless conjugate parameter, which varies between zero (insulated wall) and infinity (wall temperature remains constant). The important findings in this study are the variation of the surface temperature and heat flux from the stretching surface with the conjugate parameter and Prandtl number. It is found that these parameters have essential effects on the heat transfer characteristics. © 2010 Taiwan Institute of Chemical Engineers.

Ishak A.,National University of Malaysia | Lok Y.Y.,University Technical Malaysia Melaka | Pop I.,Technical University of Cluj Napoca
Chemical Engineering Communications | Year: 2010

An analysis is carried out to study the steady two-dimensional stagnation-point flow of a micropolar fluid over a shrinking sheet in its own plane. The shrinking velocity and the ambient fluid velocity are assumed to vary linearly with the distance from the stagnation point. The features of the flow characteristics are analyzed and discussed. Different from a stretching sheet, it is found that the solutions for a shrinking sheet are nonunique. © Taylor & Francis Group, LLC.

Bachok N.,University Putra Malaysia | Ishak A.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2010

An analysis is carried out to study the steady two-dimensional stagnation-point flow and heat transfer from a warm, laminar liquid flow to a melting stretching/shrinking sheet. The governing partial differential equations are converted into ordinary differential equations by similarity transformation, before being solved numerically using the Runge-Kutta-Fehlberg method. Results for the skin friction coefficient, local Nusselt number, velocity profiles as well as temperature profiles are presented for different values of the governing parameters. Effects of the melting parameter, stretching/shrinking parameter and Prandtl number on the flow and heat transfer characteristics are thoroughly examined. Different from a stretching sheet, it is found that the solutions for a shrinking sheet are non-unique. © 2010 Elsevier B.V.

Nadzirin N.,National University of Malaysia | Gardiner E.J.,Information School | Willett P.,Information School | Artymiuk P.J.,University of Sheffield | Firdaus-Raih M.,National University of Malaysia
Nucleic Acids Research | Year: 2012

Similarities in the 3D patterns of amino acid side chains can provide insights into their function despite the absence of any detectable sequence or fold similarities. Search for protein sites (SPRITE) and amino acid pattern search for substructures and motifs (ASSAM) are graph theoretical programs that can search for 3D amino side chain matches in protein structures, by representing the amino acid side chains as pseudo-atoms. The geometric relationship of the pseudo-atoms to each other as a pattern can be represented as a labeled graph where the pseudo-atoms are the graph's nodes while the edges are the inter-pseudo-atomic distances. Both programs require the input file to be in the PDB format. The objective of using SPRITE is to identify matches of side chains in a query structure to patterns with characterized function. In contrast, a 3D pattern of interest can be searched for existing occurrences in available PDB structures using ASSAM. Both programs are freely accessible without any login requirement. SPRITE is available at http://mfrlab.org/grafss/ sprite/while ASSAM can be accessed at http://mfrlab.org/grafss/assam/. © 2012 The Author(s).

Halib N.,Bahagian Technology Perubatan | Amin M.C.I.M.,National University of Malaysia | Ahmad I.,National University of Malaysia
Sains Malaysiana | Year: 2012

Nata de coco, a dessert originally from the Philippines is produced by fermentation of coconut water with a culture of Acetobacter xylinum, a gram negative bacterium. Acetobacter xylinum metabolizes glucose in coconut juice and converts it into bacterial cellulose that has unique properties including high purity, crystallinity and mechanical strength. Because the main component of nata de coco is bacterial cellulose, nata de coco was purified, extracted and characterized to determine whether pure cellulose could be isolated from it. The FTIR spectra of bacterial cellulose from nata de coco showed distinguish peaks of 3440 cm-1, 2926 cm-1, 1300 cm-1, 1440 cm-1, 1163 cm-1 and 1040 cm-1, which correspond to O-H stretching, C-H stretching, C-H bending, CH2 bending, C-O-C stretching and C-O stretching, respectively, and represent the fingerprints of pure cellulose component. Moreover, the FTIR curve showed a pattern similar to other bacterial cellulose spectra reported by report. Thermal analysis showed a DTG peak at 342°C, which falls in the range of cellulose degradation peaks (330°C - 370°C). On the other hand, the TGA curve showed 1 step of degradation, and this finding confirmed the purity of nata de coco. Bacterial cellulose powder produced from nata de coco was found to be soluble only in cupriethylenediamine, a well known solvent for cellulose; thus, it was confirmed that nata de coco is a good source of bacterial cellulose. The purity of bacterial cellulose produced from nata de coco renders it suitable for research that uses pure cellulose.

Drack M.,University of Vienna | Gebeshuber I.C.,National University of Malaysia | Gebeshuber I.C.,Vienna University of Technology
Soft Matter | Year: 2013

We try to clarify some issues that were raised by an article that appeared in Soft Matter, 2012, 8, 6675. The main question was how to distinguish biomimetic, bioinspired and biokleptic research. We put forward a "continental" perspective that can help to avoid some of the confusion that might have been evoked. This journal is © 2013 The Royal Society of Chemistry.

Oshkovr S.A.,National University of Malaysia | Eshkoor R.A.,National University of Malaysia | Taher S.T.,Fibigerstraed | Ariffin A.K.,National University of Malaysia | Azhari C.H.,National University of Malaysia
Composite Structures | Year: 2012

This research concentrates on the evaluation of crashworthiness characteristics of natural silk/epoxy composite square tubes energy-absorbers. Composite laminate specimens were subjected to static axial compression load and experimental evaluation of the energy absorption capability of silk/epoxy composite. Specimens were in the form of square cross-sections with the dimension of 80mm×80mm and a radius curvature of 5mm. The variables in the experiment were the length of the tubes built 50mm, 80mm and 120mm. Meanwhile, the thickness of the walls, consisting of laminates of silk/epoxy of 12, 24 and 30 plies, correspond to equivalent wall thickness of 1.7mm, 3.4mm and 4.2mm, respectively. The parameters measured were the total absorbed energy (E total), and the crash force efficiency (CFE). E total is the measure of the amount of energy that the structure can withstand without failure and thus is a measure of its strength, while CFE gives a quantitative indication of the mode of failure of the composites. The mode of failure was observed using photography. © 2012 Elsevier Ltd.

Abdul Karim S.A.,Petronas University of Technology | Pang K.V.,Universiti Sains Malaysia | Hashim I.,National University of Malaysia
AIP Conference Proceedings | Year: 2013

In this paper, we study the shape preserving interpolation for positive data using a rational quartic spline which has a quartic numerator and linear denominator. The rational quartic splines have GC1 continuity at join knots. Simple data dependent constraints are derived on the shape parameters in the description of the rational interpolant. Numerical comparison between the proposed scheme and the existing scheme is discussed. The results indicate that the proposed scheme works well for all tested data sets. © 2013 AIP Publishing LLC.

Ishak A.,National University of Malaysia | Nazar R.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
International Journal of Heat and Mass Transfer | Year: 2010

This work considers a steady two-dimensional magnetohydrodynamic (MHD) flow of a viscous, incompressible and electrically conducting fluid over a stretching vertical surface with constant wall temperature. The external flow and the stretching velocities are assumed to vary with x, where x is the distance from the slot where the surface is issued. The transformed boundary layer equations are solved numerically for some values of the related parameters, namely the magnetic parameter M, the velocity ratio parameter and the mixed convection or buoyancy parameter λ, while the Prandtl number Pr is fixed to unity, using a finite-difference scheme known as the Keller-box method. Both assisting and opposing flow cases are considered. It is found that the magnetic parameter M significantly affects the flow and the thermal fields, besides increasing the range of λ for which the solution exists. Dual solutions are found to exist for some range of the mixed convection parameter. © 2010 Elsevier Ltd. All rights reserved.

Ishak A.,National University of Malaysia | Nazar R.,National University of Malaysia | Bachok N.,University Putra Malaysia | Pop I.,Technical University of Cluj Napoca
Physica A: Statistical Mechanics and its Applications | Year: 2010

The steady magnetohydrodynamic (MHD) mixed convection boundary layer flow of a viscous and electrically conducting fluid near the stagnation-point on a vertical permeable surface is investigated in this study. The velocity of the external flow and the temperature of the plate surface are assumed to vary linearly with the distance from the stagnation-point. The governing partial differential equations are first transformed into ordinary differential equations, before being solved numerically by a finite-difference method. The features of the flow and heat transfer characteristics for different values of the governing parameters are analyzed and discussed. Both assisting and opposing flows are considered. It is found that dual solutions exist for both cases, and the range of the mixed convection parameter for which the solution exists increases with suction. © 2009 Elsevier B.V. All rights reserved.

Amara A.H.,Charité - Medical University of Berlin | Aljunid S.M.,University of Kuala Lumpur | Aljunid S.M.,National University of Malaysia
Globalization and Health | Year: 2014

With the increasing trend in refugee urbanisation, growing numbers of refugees are diagnosed with chronic noncommunicable diseases (NCDs). However, with few exceptions, the local and international communities prioritise communicable diseases. The aim of this study is to review the literature to determine the prevalence and distribution of chronic NCDs among urban refugees living in developing countries, to report refugee access to health care for NCDs and to compare the prevalence of NCDs among urban refugees with the prevalence in their home countries. Major search engines and refugee agency websites were systematically searched between June and July 2012 for articles and reports on NCD prevalence among urban refugees. Most studies were conducted in the Middle East and indicated a high prevalence of NCDs among urban refugees in this region, but in general, the prevalence varied by refugees' region or country of origin. Hypertension, musculoskeletal disease, diabetes and chronic respiratory disease were the major diseases observed. In general, most urban refugees in developing countries have adequate access to primary health care services. Further investigations are needed to document the burden of NCDs among urban refugees and to identify their need for health care in developing countries. © 2014 Amara and Aljunid; licensee BioMed Central Ltd.

Yacob N.A.,University Technology of MARA | Ishak A.,National University of Malaysia | Ishak A.,University of Malaya | Pop I.,Technical University of Cluj Napoca
Computers and Fluids | Year: 2011

The steady boundary layer stagnation-point flow of a micropolar fluid towards a horizontal linearly stretching/shrinking sheet is investigated. A mathematical model is developed to study the heat transfer characteristics occurring during the melting process due to a stretching/shrinking sheet. The transformed non-linear ordinary differential equations governing the flow are solved numerically by the Runge-Kutta-Fehlberg method with shooting technique. It is found that dual solutions exist for the shrinking case, while for the stretching case, the solution is unique. © 2011 Elsevier Ltd.

Bachok N.,University Putra Malaysia | Ishak A.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
Acta Mechanica Sinica/Lixue Xuebao | Year: 2012

An analysis is performed to study the heat transfer characteristics of steady two-dimensional boundary layer flow past a moving permeable flat plate in a nanofluid. The effects of uniform suction and injection on the flow field and heat transfer characteristics are numerically studied by using an implicit finite difference method. It is found that dual solutions exist when the plate and the free stream move in the opposite directions. The results indicate that suction delays the boundary layer separation, while injection accelerates it. © 2012 The Chinese Society of Theoretical and Applied Mechanics; Institute of Mechanics, Chinese Academy of Sciences and Springer-Verlag Berlin Heidelberg.

Bachok N.,University Putra Malaysia | Ishak A.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
International Journal of Thermal Sciences | Year: 2010

The steady boundary-layer flow of a nanofluid past a moving semi-infinite flat plate in a uniform free stream is investigated. The plate is assumed to move in the same or opposite directions to the free stream. The resulting system of nonlinear ordinary differential equations is solved numerically using the Keller-box method. Numerical results are obtained for the skin-friction coefficient, the local Nusselt number and the local Sherwood number as well as the velocity, temperature and the nanoparticle volume fraction profiles for some values of the governing parameters, namely, the plate velocity parameter, Prandtl number, Lewis number, the Brownian motion parameter and the thermophoresis parameter. The results indicate that dual solutions exist when the plate and the free stream move in the opposite directions. © 2010 Elsevier Masson SAS. All rights reserved.

Rosali H.,University Putra Malaysia | Ishak A.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
International Communications in Heat and Mass Transfer | Year: 2011

The steady stagnation point flow and heat transfer over a shrinking sheet in a porous medium is studied. A similarity transformation is used to reduce the governing system of partial differential equations to a set of nonlinear ordinary differential equations which are then solved numerically using the Keller-box method. The behavior of the flow and heat transfer characteristics for different values of the governing parameters are analyzed and discussed. Results for the skin friction coefficient, local Nusselt number, velocity profiles as well as temperature profiles are presented for different values of the governing parameters. The results indicate that dual solutions exist for the shrinking case. © 2011 Elsevier Ltd.

Aman F.,University Tun Hussein Onn Malaysia | Ishak A.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
International Communications in Heat and Mass Transfer | Year: 2013

The steady two-dimensional stagnation-point flow over a linearly stretching/shrinking sheet in a viscous and incompressible fluid in the presence of a magnetic field is studied. The governing partial differential equations are reduced to nonlinear ordinary differential equations by a similarity transformation, before being solved numerically by a shooting method. Results show that the skin friction coefficient decreases, but the heat transfer rate at the surface increases when the effect of slip at the boundary is taken into consideration. Dual solutions are found to exist for the shrinking sheet, while for the stretching sheet, the solution is unique. © 2013 Elsevier Ltd.

Yacob N.A.,University Technology of MARA | Ishak A.,National University of Malaysia | Ishak A.,University of Malaya | Nazar R.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
International Communications in Heat and Mass Transfer | Year: 2011

An analysis is carried out to study the problem of the steady flow and heat transfer over a static or moving wedge with a prescribed surface heat flux in a nanofluid. The governing partial differential equations are transformed into a set of nonlinear ordinary differential equations using similarity transformation, before being solved numerically by the Keller box method and the Runge-Kutta-Fehlberg method with shooting technique. The features of the flow and heat transfer characteristics are analyzed and discussed. Three different types of nanoparticles are considered, namely copper Cu, alumina Al2O3 and titania TiO2 with water as the base fluid. It is found that the skin friction coefficient and the heat transfer rate at the surface are highest for copper-water nanofluid compared to the alumina-water and titania-water nanofluids. Moreover, the heat transfer rate at the surface increases with the Falkner-Skan power law parameter m. © 2010 Elsevier Ltd.

Abdul Kadir N.B.,National University of Malaysia | Bifulco A.,University of London
Social Psychiatry and Psychiatric Epidemiology | Year: 2011

Introduction: The experiences of married and single mothers were compared in an investigation of psychosocial vulnerability, stress and depression in a community-based study of Moslem mothers in Malaysia. For the first time, a model of vulnerability-provoking agent originally developed by Brown et al. in the UK was tested in a Malaysian context. Methods: A cross-sectional study was carried out in the district of Johor Bahru, Malaysia. Of the 1,200 women approached from membership of community associations, 1,002 (84%) completed the questionnaires. Severe life events Recent Life Events Questionnaire (Brugha and Cragg in Acta Psychiatr Scand 82:77-81, 1990) and psychosocial vulnerability (VDQ) (Moran et al. in Br J Clin Psychol 40:411-427, 2001) were used to measure vulnerability factors. Depression was measured by the General Health Questionnaire (GHQ-30) (Havenaar et al. in Soc Psychiatry Psychiatr Epidemiol 43:209-215, 2008). Results: Single mothers had significantly higher rates of depression than those married (60.5 vs. 39.5%), as well as higher rates of severe life events and Negative Elements in Close Relationships (lack of support and conflict with children). However, married mothers had greater Negative Evaluation of Self. The two vulnerability factors were correlated to each other and to severe life events and social adversity. Logistic regression showed an interaction between severe life events in the material and relationship domains and joint vulnerability for depression outcome. The results are discussed in relation to the low recognition of psychosocial risks for depression in single mothers in Malaysia, as well as lack of appropriate services. © 2010 Springer-Verlag.

The sugar obtained after enzymatic hydrolysis of empty fruit bunches (EFBs increased from 17% to 24% when supercritical carbon dioxide (SC-CO2) pretreatment of the EFBs was used, according to a new study. SC-CO2 pretreatment plus premixing of the EFBs with alkali further increased the glucose yield to almost 37%, as reported in the study published in Industrial Biotechnology. Nurul Hazirah Che Hamzah, Masturah Markom, Osman Hassan, and Shuhaida Harun, National University of Malaysia, Selangor, provide visual evidence of the surface changes of pretreated EFBs, which appeared swollen and ruptured compared to the surface of the untreated EFBs. The researchers compared the effects of SC-CO2 pretreatment under different conditions. In the article "Investigation of the Effect of Supercritical Carbon Dioxide Pretreatment on Sugar Yield Prior to Enzymatic Hydrolysis of Empty Fruit Bunches" they show that glucose yields increased with higher pretreatment temperature, pressure, and time. "Capturing the international dimensions of industrial biotechnology innovation is one of the major focuses of our journal," says Co-Editor-in-Chief Larry Walker, PhD. More information: The article is available for free download on the Industrial Biotechnology website.

Musa A.Y.,University of Western Ontario | Musa A.Y.,National University of Malaysia | Jalgham R.T.T.,National University of Malaysia | Mohamad A.B.,National University of Malaysia
Corrosion Science | Year: 2012

The abilities of phthalazine derivatives, including phthalazine (PT), phthalazone (PTO) and phthalhydrazide (PTD), to inhibit the corrosion of mild steel in 1. M HCl at 30°C were studied using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. Theoretical calculations were performed to investigate the electronic structures of the PT derivatives. Our results showed that the inhibition efficiencies of these derivatives improved with increases in concentration. The data also showed that PTD < PT < PTO in terms of the inhibiting efficiency. Theoretical calculations also revealed that PTO is expected to be the best inhibitor among the studied phthalazine derivatives. © 2011 Elsevier Ltd.

Liu L.,University of Hong Kong | Cheung S.W.,University of Hong Kong | Azim R.,National University of Malaysia | Islam M.T.,National University of Malaysia
Microwave and Optical Technology Letters | Year: 2011

A simple circular-ring planar-monopole antenna, with a compact size of 26 × 28 mm2, fed by an offset-microstrip line, is proposed. The antenna is composed of a circular-ring radiator and a ground plane with a small rectangular slot cut along the upper edge for ultra-wideband (UWB) operation. Studies of the antenna are carried out using computer simulation. Prototype of the antenna is used for verification of the simulation results. Results show that the antenna has an impedance bandwidth of more than 132% (from 3.7 to more than 18 GHz) for the standing wave ratio of less than 2 (voltage standing wave ratio, VSWR ≤ 2), a stable omnidirectional radiation pattern and an average peak gain of 3.97 dBi across the UWB, making the antenna a good candidate for use in UWB communications. © 2011 Wiley Periodicals, Inc.

Reza M.I.H.,National University of Malaysia | Reza M.I.H.,Chittagong University | Abdullah S.A.,National University of Malaysia
Ecological Indicators | Year: 2011

An ecosystem is a complex composition of physical, chemical and biological components. This complex system remains in a healthy state if the system can maintain the ecological equilibrium among its components. Anthropogenic disturbances are the prime stressors that affect this equilibrium through creating fragmentation, ecosystem sensitivity, loosening landscape connectivity and disrupting ecological integrity. As different types of ecosystem are interconnected, a comprehensive monitoring and evaluating criteria is needed for measuring its integrity at regional level for conservation planning. A Regional Index of Ecological Integrity can be a suitable approach for sustainable management of regional ecosystem. Therefore, this paper presents (i) the characteristics of ecological integrity, (ii) the spatial processes induced by anthropogenic stressors and (iii) an approach to develop a composite Regional Index of Ecological Integrity (RIEI). The prime objective is to establish a thought and a way to develop a composite index of ecological integrity at the regional level. Here, we demonstrate different compositional, structural and functional indicators/indices related to fragmentation, representativeness of protected area, ecosystem sensitivity, and landscape connectivity for the development of a Regional Index of Ecological Integrity (RIEI). © 2010 Elsevier Ltd. All rights reserved.

Nabil S.,National University of Malaysia | Samman N.,University of Hong Kong
International Journal of Oral and Maxillofacial Surgery | Year: 2012

This review examines the effect of publishing case reports on journal impact factor and future research. All case reports published in the four major English language oral and maxillofacial surgery journals in the two year period, 2007-2008, were searched manually. The citation data of each case report were retrieved from the ISI online database. The number, percentage and mean citations received by case reports and their relation to the 2009 journal impact factor were analysed. Case reports which received more than 5 citations were also identified and all of the citing articles retrieved and analysed. Thirty-one percent of all articles published in major oral and maxillofacial journals in 2007-2008 were case reports. Case reports had a low citation rate with a mean citation of less than 1. There were 38 (7.2%) case reports with more than 5 citations and 30% of the citing articles were also case reports. The publication of case reports negatively affected journal impact factor which correlated directly with the percentage of case reports published within a journal. Case reports reporting recent topics, describing new treatment/diagnosis method and with a literature review were more likely to receive citations. © 2012 International Association of Oral and Maxillofacial Surgeons.

Wong M.M.L.,National University of Malaysia | Cannon C.H.,CAS Xishuangbanna Tropical Botanical Garden | Cannon C.H.,Texas Tech University | Wickneswari R.,National University of Malaysia
BMC Genomics | Year: 2011

Background: Acacia auriculiformis × Acacia mangium hybrids are commercially important trees for the timber and pulp industry in Southeast Asia. Increasing pulp yield while reducing pulping costs are major objectives of tree breeding programs. The general monolignol biosynthesis and secondary cell wall formation pathways are well-characterized but genes in these pathways are poorly characterized in Acacia hybrids. RNA-seq on short-read platforms is a rapid approach for obtaining comprehensive transcriptomic data and to discover informative sequence variants.Results: We sequenced transcriptomes of A. auriculiformis and A. mangium from non-normalized cDNA libraries synthesized from pooled young stem and inner bark tissues using paired-end libraries and a single lane of an Illumina GAII machine. De novo assembly produced a total of 42,217 and 35,759 contigs with an average length of 496 bp and 498 bp for A. auriculiformis and A. mangium respectively. The assemblies of A. auriculiformis and A. mangium had a total length of 21,022,649 bp and 17,838,260 bp, respectively, with the largest contig 15,262 bp long. We detected all ten monolignol biosynthetic genes using Blastx and further analysis revealed 18 lignin isoforms for each species. We also identified five contigs homologous to R2R3-MYB proteins in other plant species that are involved in transcriptional regulation of secondary cell wall formation and lignin deposition. We searched the contigs against public microRNA database and predicted the stem-loop structures of six highly conserved microRNA families (miR319, miR396, miR160, miR172, miR162 and miR168) and one legume-specific family (miR2086). Three microRNA target genes were predicted to be involved in wood formation and flavonoid biosynthesis. By using the assemblies as a reference, we discovered 16,648 and 9,335 high quality putative Single Nucleotide Polymorphisms (SNPs) in the transcriptomes of A. auriculiformis and A. mangium, respectively, thus yielding useful markers for population genetics studies and marker-assisted selection.Conclusion: We have produced the first comprehensive transcriptome-wide analysis in A. auriculiformis and A. mangium using de novo assembly techniques. Our high quality and comprehensive assemblies allowed the identification of many genes in the lignin biosynthesis and secondary cell wall formation in Acacia hybrids. Our results demonstrated that Next Generation Sequencing is a cost-effective method for gene discovery, identification of regulatory sequences, and informative markers in a non-model plant. © 2011 Wong et al; licensee BioMed Central Ltd.

Farahani G.N.,Islamic Azad University | Ahmad I.,National University of Malaysia | Mosadeghzad Z.,Islamic Azad University
Polymer - Plastics Technology and Engineering | Year: 2012

Kenaf fibers were mixed with unsaturated polyester resin (UPR), which was prepared by recycling of polyethylene therephthalate (PET) waste bottles. Grinded PET waste bottles were subjected to recycle by glycolysis which was used to prepare unsaturated polyester resin. The resin was then mixed with kenaf fibers in two different lengths (2.5 and 5 mm) at different fiber loading (2.5 and 5 phr of kenaf in UPR resin). The effects of fiber content, fiber size and surface treatment on the mechanical properties, density and water absorption of the composite were studied. The SEM and FTIR analysis were used to analyse the influence of alkali treatment on fibers and interfacial interaction between fibers and matrix. The results show that the optimum values of the stiffness properties and impact strength is at 2.5 phr, whereas tensile strength decreases with increasing fiber content. The length of fiber played a significant role in some of the mechanical properties of the composites with 5 mm fiber length has higher mechanical properties than 2.5 mm length. The results also showed that alkali treatment causes a better adhesion between the fiber and UPR matrix and improves the mechanical properties of the composites. Furthermore, surface treatment reduced the water absorption of composites. © 2012 Copyright Taylor and Francis Group, LLC.

Lai M.H.,University Malaysia Sarawak | Maniam T.,National University of Malaysia | Chan L.F.,National University of Malaysia | Ravindran A.V.,National University of Malaysia | Ravindran A.V.,University of Toronto
Journal of Medical Internet Research | Year: 2014

Background: Suicide is a serious and increasing problem worldwide. The emergence of the digital world has had a tremendous impact on people's lives, both negative and positive, including an impact on suicidal behaviors. Objective: Our aim was to perform a review of the published literature on Web-based suicide prevention strategies, focusing on their efficacy, benefits, and challenges. Methods: The EBSCOhost (Medline, PsycINFO, CINAHL), OvidSP, the Cochrane Library, and ScienceDirect databases were searched for literature regarding Web-based suicide prevention strategies from 1997 to 2013 according to the modified PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. The selected articles were subjected to quality rating and data extraction. Results: Good quality literature was surprisingly sparse, with only 15 fulfilling criteria for inclusion in the review, and most were rated as being medium to low quality. Internet-based cognitive behavior therapy (iCBT) reduced suicidal ideation in the general population in two randomized controlled trial (effect sizes, d=0.04-0.45) and in a clinical audit of depressed primary care patients. Descriptive studies reported improved accessibility and reduced barriers to treatment with Internet among students. Besides automated iCBT, preventive strategies were mainly interactive (email communication, online individual or supervised group support) or information-based (website postings). The benefits and potential challenges of accessibility, anonymity, and text-based communication as key components for Web-based suicide prevention strategies were emphasized. Conclusions: There is preliminary evidence that suggests the probable benefit of Web-based strategies in suicide prevention. Future larger systematic research is needed to confirm the effectiveness and risk benefit ratio of such strategies.

Siow K.S.,University of South Australia | Siow K.S.,National University of Malaysia | Kumar S.,University of South Australia | Griesser H.J.,University of South Australia
Plasma Processes and Polymers | Year: 2015

This review surveys low-pressure plasma-based methods for producing hydrophilic and hydrogel-like bio-interface coatings without reactive functional groups in aqueous media. The main focus of the review is one-step plasma polymerization; other plasma-based methods such as plasma with grafting are also discussed within the context of monomers used, process development, ageing properties, and interaction of these coatings with proteins and cells. Coatings containing polyethylene glycol (PEG) or polyethylene oxide (PEO), acrylamides such as N-isopropylacrylamide (NIPAM), and sulfonate (SO3) or sulfate (SO4) moieties are reviewed here. © 2014 Wiley-VCH Verlag GmbH & Co. KGaA.

Hishamuddin H.,University of New South Wales | Hishamuddin H.,National University of Malaysia | Sarker R.A.,University of New South Wales | Essam D.,University of New South Wales
Computers and Industrial Engineering | Year: 2013

Supply chains are becoming increasingly competitive and complex in order to effectively meet customer demands. These characteristics make supply chains vulnerable to various risks, including disruptions. In this study, a recovery model is explored for a two-stage production and inventory system with the possibility of transportation disruption. This model is capable of determining the optimal ordering and production quantities during the recovery window, and ensuring that the total relevant costs are minimized, while seeking to recover the original schedule. An efficient heuristic was developed to solve the model. The results showed that the optimal recovery schedule is highly dependent on the relationship between the backorder cost and the lost sales cost parameters. In addition, the heuristic was able to give quality solutions for the model, with very small deviations of the heuristic solutions from the optimal value. Such tools are useful in assisting managers towards effective decision making, particularly in determining the optimal recovery strategy for the longevity and sustainability of their firms undergoing disruptions. © 2012 Elsevier Ltd. All rights reserved.

Nabil S.,National University of Malaysia | Samman N.,University of Hong Kong
Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology | Year: 2012

Objective. This systematic review aimed to answer the clinical question, "What is the current risk of developing osteoradionecrosis of the jaws among irradiated head and neck cancer patients?" Study Design. A systematic review of published English-language randomized controlled trials on the outcome of radiation therapy was performed via Medline and Embase databases. Data on osteoradionecrosis/bone toxicity were collected and analyzed. Results. Twenty-two articles reporting on a total of 5,742 patients were selected for final review based on strict eligibility criteria. An estimated 2% of the head and neck-irradiated patients are at risk of developing osteoradionecrosis. Patients receiving adjunctive radiotherapy, accelerated fractionation without dose reduction, and chemoradiotherapy show no increase in osteoradionecrosis risk. Accelerated fractionation with dose reduction is associated with a reduced risk, whereas hyperfractionation shows elevated risk of developing osteoradionecrosis. Conclusions. The risk of developing osteoradionecrosis among the irradiated head and neck cancer patient has significantly declined in recent years. © 2012 Elsevier Inc. All rights reserved.

Abdullah S.,National University of Malaysia | Turabieh H.,National University of Malaysia | McCollum B.,Queen's University of Belfast | McMullan P.,Queen's University of Belfast
Journal of Heuristics | Year: 2012

This paper describes the development of a novel metaheuristic that combines an electromagnetic-like mechanism (EM) and the great deluge algorithm (GD) for the University course timetabling problem. This well-known timetabling problem assigns lectures to specific numbers of timeslots and rooms maximizing the overall quality of the timetable while taking various constraints into account. EM is a population-based stochastic global optimization algorithm that is based on the theory of physics, simulating attraction and repulsion of sample points in moving toward optimality. GD is a local search procedure that allows worse solutions to be accepted based on some given upper boundary or 'level'. In this paper, the dynamic force calculated from the attraction-repulsion mechanism is used as a decreasing rate to update the 'level' within the search process. The proposed method has been applied to a range of benchmark university course timetabling test problems from the literature. Moreover, the viability of the method has been tested by comparing its results with other reported results from the literature, demonstrating that the method is able to produce improved solutions to those currently published. We believe this is due to the combination of both approaches and the ability of the resultant algorithm to converge all solutions at every search process. © Springer Science+Business Media, LLC 2011.

Sajab M.S.,National University of Malaysia | Chia C.H.,National University of Malaysia | Zakaria S.,National University of Malaysia | Khiew P.S.,University of Nottingham Malaysia Campus
Bioresource Technology | Year: 2013

Oil palm empty fruit bunch (EFB) fibers were employed to remove dyes from aqueous solutions via adsorption approaches. The EFB fibers were modified using citric acid (CA) and polyethylenimine (PEI) to produce anionic and cationic adsorbents, respectively. The CA modified EFB fibers (CA-EFB) and PEI-modified EFB fibers (PEI-EFB) were used to study the efficiency in removing cationic methylene blue (MB) and anionic phenol red (PR) from aqueous solutions, respectively, at different pHs, temperatures and initial dye concentrations. The adsorption data for MB on the CA-EFB fitted the Langmuir isotherm, while the adsorption of PR on the PEI-EFB fitted the Freundlich isotherm, suggesting a monolayer and heterogeneous adsorption behavior of the adsorption processes, respectively. Both modified fibers can be regenerated up to seven adsorption/desorption cycles while still providing as least 70% of the initial adsorption capacity. © 2012 Elsevier Ltd.

Fadilah S.A.W.,National University of Malaysia | Aqilah M.P.,National University of Malaysia
Stem Cell Reviews and Reports | Year: 2012

Allogeneic hematopoietic stem cell transplantation (HSCT) remains a potential curative option for many patients with hematological malignancies (HM). However, the high rate of transplantation-related mortality (TRM) restricted the use of standard myeloablative HSCT to a minority of young and fit patients. Over the past few years, it has become evident that the alloreactivity of the immunocompetent donor cells mediated anti-malignancy effects independent of the action of high dose chemoradiotherapy. The use of reduced intensity conditioning (RIC) regimens has allowed a graft-versus-malignancy (GvM) effect to be exploited in patients who were previously ineligible for HSCT on the grounds of age and comorbidity. Retrospective analysis showed that RIC has been associated with lower TRM but a higher relapse rate leading to similar intermediate term overall and progression-free survivals when compared to standard myeloablative HSCT. However, the long term antitumor effect of this approach is less well established. Prospective studies are ongoing to define which patients might most benefit from reduced toxicity stem cell transplant (RT-SCT) and which transplant protocols are suitable for the different types of HM. The advent of RT-SCT permits the delivery of a potentially curative GvM effect to the majority of patients with HM whose outcome with conventional chemotherapy would be dismal. Remaining challenges include development of effective strategies to reduce relapse rates by augmenting GvM effects without increasing toxicity. © 2012 Springer Science+Business Media, LLC.

Hamidah A.,National University of Malaysia
Tropical medicine & international health : TM & IH | Year: 2014

To determine the behavioural impact of chemotherapy in survivors of acute lymphoblastic leukaemia (ALL) treated with chemotherapy only and to identify treatment-related or sociodemography-related factors that might be associated with behavioural outcome. We examined 57 survivors of childhood ALL, who were off treatment for at least 2 years and were in remission, aged 4-18 years, and 221 unrelated healthy controls. The Child Behaviour Checklist (CBCL) parent report was used either in English or in Bahasa Malaysia (the national language of Malaysia) to assess the behavioural outcome. Childhood ALL survivors had significantly higher scores on externalising behaviour on the CBCL parent report than did controls. Higher problem scores were found in ALL survivors with single parents on 'total problems' (P = 0.03) and subscales 'withdrawn' (P = 0.03), 'social problems' (P < 0.01) and 'delinquent behaviour' (P = 0.03) than in survivors with married parents. Significant associations were seen between a lower education level of the father and the variables representing internalising (withdrawn, anxious/depressed) and externalising (aggressive behaviour). We observed trends on higher scores in all scales in ALL survivors with single parents than in controls with single parents or with fathers with low education level, especially primary education only. Malaysian childhood ALL survivors had a significantly increased risk for externalising behavioural problems, and there was a trend towards increased risk of problems in many other behavioural scales. Understanding the sociocultural dimension of patients' health is important to be able to design the most appropriate remedy for problem behaviours detected in this multi-ethnic population. © 2014 John Wiley & Sons Ltd.

Yau Y.H.,University of Malaya | Hasbi S.,National University of Malaysia
Indoor and Built Environment | Year: 2015

Even though the green building concept is fairly new in Malaysia, the development of this industry has been growing in recent years prior to the launch of Malaysia's own standard, namely the Green Building Index (GBI). One of the criteria assessed in the GBI is the energy efficiency, which takes about 21% of the overall assessment. Considering this, the passive design has been included in the green building concept to reduce the energy usage without compromising occupant thermal comfort. This study attempts to assess the passive design effectiveness in terms of indoor air quality in green office buildings in the tropics. Two green office buildings that incorporated the radiant slab cooling and conventional cooling system have been selected as case studies. A detailed assessment in terms of thermal comfort parameters (temperature and relative humidity), indoor pollutants' concentration (carbon dioxide, carbon monoxide and formaldehyde) and air movement was carried out. The results showed that the thermal comfort parameters fall within the Malaysian Standard (MS1525:2007) and ASHRAE Standard-55 2010 except for the air movement in both buildings. Based on the results obtained, future buildings using the radiant slab cooling can have a better comfort level from the lesson learned from both buildings. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Shahadi H.I.,National University of Malaysia | Jidin R.,National University of Malaysia
Proceedings of the 2011 7th International Conference on Information Assurance and Security, IAS 2011 | Year: 2011

Steganography is an information hiding technique where secret message is embedded into unsuspicious cover signal. Measurement of good steganography algorithm includes security, capacity, robustness and imperceptibility. These measures are contradicted, therefore improving one, affects the others. In this paper, we propose a new high capacity audio steganography algorithm based on the wavelet packet transform with adaptive hiding in least significant bits. The adaptive hiding is determined depend on the cover samples strength and bits block matching between message and cover signals. The results show that message can be embedded up to 42 % of the total size of the cover audio signal with at least of 50 dB signal to noise ratio. © 2011 IEEE.

Choudhury P.K.,National University of Malaysia
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

Propagation characteristics of optical fibers are greatly dependent on materials, which the guides are comprised of. Varieties of materials have been developed and investigated for their usage in fabricating optical fibers for specific applications. Within the context, a liquid crystal medium is both inhomogeneous and optically anisotropic, and fibers made of such mediums are greatly useful. Also, liquid crystals exhibit strong electro-optic behavior, which allows alternation in their optical properties under the influence of external electric fields. These features make liquid crystal fibers greatly important for optical applications. The present communication is aimed at providing a glimpse of the efficacy of liquid crystals and/or fibers made of liquid crystals, followed by the analytical investigation of wave propagation through such guides. The sustainment of modes is explored in these fibers under varying fiber dimensions, and the novelty is discussed. The case of tapered liquid crystal fibers is also briefly discussed highlighting the usefulness. Control on the dispersion characteristics of such fibers may be imposed by making the guide even more complex; the possibility of devising such options is also touched upon. © 2013 Copyright SPIE.

Chin K.-Y.,National University of Malaysia | Ima-Nirwana S.,National University of Malaysia
Nutrients | Year: 2014

Recent studies have found conflicting evidence on the role of α-tocopherol (αTF) on bone health. This nonsystematic review aimed to summarize the current evidence on the effects of αTF on bone health from cell culture, animal, and human studies in order to clarify the role of αTF on bone health. Our review found that αTF exerted beneficial, harmful or null effects on bone formation cells. Animal studies generally showed positive effects of αTF supplementation on bone in various models of osteoporosis. However, high-dose αTF was possibly detrimental to bone in normal animals. Human studies mostly demonstrated a positive relationship between αTF, as assessed using high performance liquid chromatography and/or dietary questionnaire, and bone health, as assessed using bone mineral density and/or fracture incidence. Three possible reasons high dosage of αTF can be detrimental to bone include its interference with Vitamin K function on bone, the blocking of the entry of other Vitamin E isomers beneficial to bone, and the role of αTF as a prooxidant. However, these adverse effects have not been shown in human studies. In conclusion, αTF may have a dual role in bone health, whereby in the appropriate doses it is beneficial but in high doses it may be harmful to bone. © 2014 by the authors; licensee MDPI, Basel, Switzerland.

Sakthiswary R.,National University of Malaysia | Suresh E.,Alexandra Hospital Jurong Health
Lupus | Year: 2014

Objective: The objective of this review is to evaluate the evidence for efficacy of methotrexate (MTX) in systemic lupus erythematosus (SLE). Methods: A comprehensive, computerized search was performed in MEDLINE (PubMed), EMBASE and the Cochrane Controlled Trials registry to screen for studies that examined the efficacy of MTX in adult SLE patients. The Jadad scoring system was used to assess study quality, and data were pooled using the random effects model. Results: Of the 53 articles that were identified, 44 were excluded. Nine studies (including three randomized controlled and six observational) were eligible for inclusion. All of the included studies predominantly involved patients with arthritis or mucocutaneous features. There was significant reduction of the SLE Disease Activity Index (SLEDAI) among MTX-treated patients when compared with controls (p=0.001, odds ratio (OR) 0.444, 95% confidence interval (CI) 0.279 to 0.707). There was also significant reduction in the average dose of corticosteroids among MTX-treated patients when compared with controls (p=0.001, OR 0.335, 95% CI 0.202 to 0.558). The effect of MTX on laboratory and serological markers, including erythrocyte sedimentation rate, anti-dsDNA and complement levels (C3 and C4), could not be determined because of the limited numbers of controlled trials. Conclusion: The use of MTX is associated with significant reductions in SLEDAI and the average dose of corticosteroids in adult patients with SLE. © The Author(s), 2013.

Samun M.A.-A.,National University of Malaysia
Research Journal of Applied Sciences | Year: 2012

A community service order is one that is viewed to be highly appropriate for juvenile offenders. However, there is still a void where extensive legalistic studies discussing this order should be, especially from the aspect of theoretical framework. In relation to this the purpose of this research is to debate the pros and cons of community service orders from the aspect of theoretical framework. This research finds that community service orders are based on rehabilitation theory and that they put the best interest of the child or juvenile first. The juvenile offenders will be integrated with society through community service orders and this process will simultaneously decrease the rate of recidivism and increase the potential for their rehabilitation.A community service order is one that is viewed to be highly appropriate for juvenile offenders. However, there is still a void where extensive legalistic studies discussin this order should be, especially from the aspect of theoretical framework. In relation to th the purpose of this research is to debate the pros and cons of community service orders from the aspect of theoretical framework. This research finds that community service orders are base on rehabilitation theory and that they put the best interest of the child or juvenile fir. Th juvenile offenders will be integrated with society through community service orders and this process will simultaneously decrease the rate of recidivism and increase the potential for their rehabilitation. © Medwell journals, 2012.

Azim R.,National University of Malaysia | Islam M.T.,National University of Malaysia | Misran N.,National University of Malaysia
Applied Computational Electromagnetics Society Journal | Year: 2011

A planar antenna and a technique for enhancing its bandwidth for UWB applications have been proposed in this paper. The proposed antenna which has a compact structure and the total size of 30 × 22 mm2 consists of a square patch and a partial ground plane. Numerical study shows that the bandwidth of the proposed antenna can be controlled mainly by the patch size and width of the feeding line. The cutting triangular shape slots on the top edge of the ground plane help to increase the bandwidth by 43.6% (3.89 GHz). The measured-10 dB return loss bandwidth of the proposed antenna ranges from 2.95 GHz to 15.45 GHz which covers the entire UWB band. The nearly stable radiation pattern with a maximum gain of 5.9 dBi makes the proposed antenna suitable for being used in UWB communication. © 2011 ACES.

Pek C.-K.,University of Nottingham Malaysia Campus | Jamal O.,National University of Malaysia
Journal of Environmental Management | Year: 2011

In Malaysia, most municipal wastes currently are disposed into poorly managed 'controlled tipping' systems with little or no pollution protection measures. This study was undertaken to assist the relevant governmental bodies and service providers to identify an improved waste disposal management strategy. The study applied the choice experiment technique to estimate the nonmarket values for a number of waste disposal technologies. Implicit prices for environmental attributes such as psychological fear, land use, air pollution, and river water quality were estimated. Compensating surplus estimates incorporating distance from the residences of the respondents to the proposed disposal facility were calculated for a number of generic and technology-specific choice sets. The resulting estimates were higher for technology-specific options, and the distance factor was a significant determinant in setting an equitable solid waste management fee. © 2011 Elsevier Ltd.

Latiff A.,National University of Malaysia
Malaysian Applied Biology | Year: 2016

Malaysia has initiated, produced and launched a National Policy on Biological Diversity in 1998 which contains policy statement, principles, objectives, rationales, strategies and above all action plans of programmes. The policy places great importance on taxonomy in realising the true dimension of biodiversity in the country and that taxonomy is a cornerstone of biodiversity has long been accepted and understood. Yet, many taxonomic institutions such as National Natural History Museum and National Herbarium are not within sight. Taxonomy is not prioritised within the R & D mechanism, capacity building is not undertaken with an accepted vigour, systematic research centres are not established, school and university curricula have not addressed taxonomic curricula, proper training of taxonomists and parataxonomists are not planned, and data management is not adequately placed either. Ironically the rate of ecosystem and habitat degradation and loss, species loss and genetic erosion are occurring at a rate unsur ssed in the past. Is there any crisis in Malaysian taxonomy and plant taxonomy in particular? The taxonomic community is small and aged. The reference collections are still small, the scientific productivity in term of publication of papers to report new species, new records, taxonomic revisions, phylogenetic relationships, variations, species loss and conservation efforts are still inadequate. The floristic treatments for the Tree Flora of Sabah and Sarawak and the Flora of Peninsular Malaysia are going-on. An attempt is made here to relate the richness of biodiversity to taxonomy so that the latter’s impediments could be properly addressed. There must be coordinated efforts to overcome the real taxonomic impediments in Malaysia. © 2016, Malaysian Society of Applied Biology. All rights reserved.

Hannan M.A.,National University of Malaysia | Arebey M.,National University of Malaysia | Begum R.A.,National University of Malaysia | Basri H.,National University of Malaysia
Waste Management | Year: 2011

This paper deals with a system of integration of Radio Frequency Identification (RFID) and communication technologies for solid waste bin and truck monitoring system. RFID, GPS, GPRS and GIS along with camera technologies have been integrated and developed the bin and truck intelligent monitoring system. A new kind of integrated theoretical framework, hardware architecture and interface algorithm has been introduced between the technologies for the successful implementation of the proposed system. In this system, bin and truck database have been developed such a way that the information of bin and truck ID, date and time of waste collection, bin status, amount of waste and bin and truck GPS coordinates etc. are complied and stored for monitoring and management activities. The results showed that the real-time image processing, histogram analysis, waste estimation and other bin information have been displayed in the GUI of the monitoring system. The real-time test and experimental results showed that the performance of the developed system was stable and satisfied the monitoring system with high practicability and validity. © 2011 Elsevier Ltd.

Bachok N.,University Putra Malaysia | Ishak A.,National University of Malaysia | Nazar R.,National University of Malaysia
Meccanica | Year: 2011

The unsteady laminar flow of an incompressible micropolar fluid over a stretching sheet is investigated. The unsteadiness in the flow and temperature fields is caused by the time-dependence of the stretching velocity and the surface temperature. Effects of the unsteadiness parameter, material parameter and Prandtl number on the flow and heat transfer characteristics are thoroughly examined. © 2010 Springer Science+Business Media B.V.

Aziz R.C.,University of Kuala Lumpur | Hashim I.,National University of Malaysia | Alomari A.K.,Jerash Private University
Meccanica | Year: 2011

This research studied the influence of internal heat generation on flow and heat transfer in a thin liquid film on an unsteady stretching sheet. The velocity and temperature fields were solved using the Homotopy Analysis Method (HAM), taking a general surface temperature into consideration. The analytical series solution are presented and the numerical results obtained are tabulated. The effects of unsteadiness parameter, Prandtl number and temperature-dependent parameter in this study are discussed and presented graphically via the velocity and temperature profiles. © Springer Science+Business Media B.V. 2010.

Mahmud M.,National University of Malaysia
International Journal of Ecology and Development | Year: 2010

The present study investigates some of the physical properties of remotely sensed aerosols that were emitted from an intense biomass burning episode over equatorial Southeast Asia during August 2005. A total of 1245 active fire counts were detected in Sumatera, Indonesia by the MODIS Aqua satellite from 8 to 14 August 2005, and consequently, increased the amount of tropospheric oceanic aerosol mass concentrations and aerosol optical depth (AOD) to more than 23 _g cm-2 and 0.8, respectively over Peninsular Malaysia. This is in contrast to lower AOD values over the uninhabited neighbouring areas such as the Bay of Bengal or the equatorial Indian Ocean. Coarser and lower mass concentrations of aerosols were detected over the equatorial Indian Ocean, in contrast to the area east of Sumatera, including Peninsular Malaysia and the southern South China Sea, where the finer sized aerosols originated mainly from the biomass burning activities. Here, the effective radii of fine sized aerosols ranged from 0.1 to 0.4 μm compared to the effective radii of coarse aerosols that were typically of size 1 μm over the equatorial Indian Ocean. Forward air trajectories showed that the fine aerosols originated from the burned biomass in Sumatera were transported downstream to Peninsular Malaysia by the prevailing southwest monsoon. The near-stagnant low level conditions that occurred from 9 to 11 August 2005 exacerbated the poor dispersion of the aerosols as corroborated by the extremely high ground level PM10 concentrations recorded on the western coast of Peninsular Malaysia. Time series of the AOD showed that the elevated turbidity of the atmosphere associated with the suspended aerosols from the intense biomass burning activities were transient in nature, which lasted for approximately a few days before the aerosols were subsequently removed from the atmosphere. © 2010 IJED.

Basri S.,National University of Malaysia | Kamarudin S.K.,National University of Malaysia
International Journal of Hydrogen Energy | Year: 2011

Among the different fuel cell technologies, the direct methanol fuel cell (DMFC) presents several interesting scientific and engineering problems such as feed and oxidant requirements, fuel utilization and recovery, scale-up, etc. There are many Process System Engineering (PSE) issues that remain unsolved. Notable among these are the structure of the DMFC and the modeling and optimization of design parameters. The PSE-related challenges discussed in this paper include the methanol and water crossover, the low kinetics rates of the reaction, heat and water management, the fuel management system, hydrodynamics studies and mass transport. Also presented in this paper are several important engineering factors for the successful stacking design of DMFCs for portable applications. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights.

Abbasbandy S.,Imam Khomeini International University | Roohani Ghehsareh H.,Imam Khomeini International University | Hashim I.,National University of Malaysia
Engineering Analysis with Boundary Elements | Year: 2013

In this paper, an efficient numerical technique is developed to approximate the solution of two-dimensional cubic nonlinear Schrödinger equations. The method is based on the nonsymmetric radial basis function collocation method (Kansa's method), within an operator Newton algorithm. In the proposed process, three-dimensional radial basis functions (especially, three-dimensional Multiquadrics (MQ) and Inverse multiquadrics (IMQ) functions) are used as the basis functions. For solving the resulting nonlinear system, an algorithm based on the Newton approach is constructed and applied. In the multilevel Newton algorithm, to overcome the instability of the standard methods for solving the resulting ill-conditioned system an interesting and efficient technique based on the Tikhonov regularization technique with GCV function method is used for solving the ill-conditioned system. Finally, the presented method is used for solving some examples of the governing problem. The comparison between the obtained numerical solutions and the exact solutions demonstrates the reliability, accuracy and efficiency of this method. © 2013 Elsevier Ltd.

Hamdani H.Y.,National University of Malaysia | Appasamy S.D.,National University of Malaysia | Willett P.,University of Sheffield | Artymiuk P.J.,University of Sheffield | Firdaus-Raih M.,National University of Malaysia
Nucleic Acids Research | Year: 2012

Similarities in the 3D patterns of RNA base interactions or arrangements can provide insights into their functions and roles in stabilization of the RNA 3D structure. Nucleic Acids Search for Substructures and Motifs (NASSAM) is a graph theoretical program that can search for 3D patterns of base arrangements by representing the bases as pseudo-atoms. The geometric relationship of the pseudo-atoms to each other as a pattern can be represented as a labeled graph where the pseudo-atoms are the graph's nodes while the edges are the inter-pseudo-atomic distances. The input files for NASSAM are PDB formatted 3D coordinates. This web server can be used to identify matches of base arrangement patterns in a query structure to annotated patterns that have been reported in the literature or that have possible functional and structural stabilization implications. The NASSAM program is freely accessible without any login requirement at http://mfrlab.org/grafss/nassam/. © 2012 The Author(s).

Abdul Kadir N.B.,National University of Malaysia | Bifulco A.,Middlesex University
Psychiatry Research | Year: 2013

The role of marital breakdown in women's mental health is of key concern in Malaysia and internationally. A cross-sectional questionnaire study of married and separated/divorced and widowed women examined insecure attachment style as an associated risk factor for depression among 1002 mothers in an urban community in Malaysia. A previous report replicated a UK-based vulnerability-provoking agent model of depression involving negative evaluation of self (NES) and negative elements in close relationships (NECRs) interacting with severe life events to model depression. This article reports on the additional contribution of insecure attachment style to the model using the Vulnerable Attachment Style Questionnaire (VASQ). The results showed that VASQ scores were highly correlated with NES, NECR and depression. A multiple regression analysis of depression with backward elimination found that VASQ scores had a significant additional effect. Group comparisons showed different risk patterns for single and married mothers. NES was the strongest risk factor for both groups, with the 'anxious style' subset of the VASQ being the best additional predictor for married mothers and the total VASQ score (general attachment insecurity) for single mothers. The findings indicate that attachment insecurity adds to a psychosocial vulnerability model of depression among mothers cross-culturally and is important in understanding and identifying risk. © 2013 Elsevier Ireland Ltd.

Bachok N.,University Putra Malaysia | Ishak A.,National University of Malaysia | Pop I.,Babes - Bolyai University
International Journal of Heat and Mass Transfer | Year: 2012

An analysis is carried out to investigate the steady two-dimensional stagnation-point flow of a water based nanofluid over an exponentially stretching/shrinking sheet in its own plane. Using a similarity transformation, the governing mathematical equations are transformed into coupled, nonlinear ordinary differential equations which are then solved numerically for three types of nanoparticles, namely copper (Cu), alumina (Al 2O 3), and titania (TiO 2) in the water based fluid with Prandtl number Pr = 6.2. The skin friction coefficient, the local Nusselt number and the velocity and temperature profiles are presented graphically and discussed. Effects of the solid volume fraction and the stretching/shrinking parameter λ on the fluid flow and heat transfer characteristics are thoroughly examined. Different from a stretching sheet, it is found that the solutions for a shrinking sheet are non-unique. The range of the parameter λ where the similarity solution exists for the steady stagnation-point flow over an exponentially stretching/shrinking sheet is larger compared with the linear stretching/shrinking case. © 2012 Elsevier Ltd. All rights reserved.

Mushrifah I.,National University of Malaysia
Biological Trace Element Research | Year: 2010

This paper aims to compare the Cd, Cu, and Pb concentration in the bone, gills, and muscle of the seven fish species sampled during normal and dry seasons. Cadmium, Cu, and Pb concentrations varied significantly depending on the type of the tissue and season. Bone samples of the Osteochilus hasseltii showed the highest concentrations of Pb (6.08 μg/g dw) during September (the dry season), whereas bone samples of the Puntioplites bulu showed the lowest concentrations of Cd (0.08 μg/g dw) during September. Muscle samples of the P. bulu indicated the highest concentrations of Cu (2.58 μg/g dw) during March (the normal season). On the other hand, muscle samples of Channa straitus sowed the lowest concentrations of Cd (0.04 μg/g dw) during July (the dry season). Gills samples of the O. hasseltii showed the highest concentration of Pb (6.56 μg/g dw) during March (the normal season), while gills samples of C. straitus indicated the lowest concentration of Cd (0.06 μg/g dw) during July (the dry season). © 2010 Springer Science+Business Media, LLC.

Wan Mohtar W.H.M.,University of Nottingham | Wan Mohtar W.H.M.,National University of Malaysia | Munro R.J.,University of Nottingham
Physics of Fluids | Year: 2013

Here, we report laboratory experiments to investigate the threshold criteria for incipient sediment motion in the presence of oscillating-grid turbulence, with the bed slope inclined at angles between the horizontal and the repose limit for the sediment. A set of nine mono-disperse sediment types was used with size ranges normally associated with either the hydraulically-smooth or transitional regimes. Measurements of the (turbulent) fluid velocity field, in the region between the grid and bedform's surface, were obtained using two-dimensional particle imaging velocimetry. Statistical analysis of the velocity data showed that the turbulence had a anisotropic structure, due to the net transfer of energy from the normal to the tangential velocity components in the near-bed region, and that the fluctuations were dominant compared to the secondary mean flow. The sediment threshold criteria for horizontal bedforms were compared with, and found to be in good qualitative agreement with the standard Shields curve. For non-horizontal bedforms, the bed mobility was found to increase with increasing bed slope, and the threshold criteria were compared with previously-reported theoretical models, based on simple force-balance arguments. © 2013 American Institute of Physics.

Roslan R.,University Tun Hussein Onn Malaysia | Saleh H.,National University of Malaysia | Hashim I.,National University of Malaysia
International Journal of Heat and Mass Transfer | Year: 2012

Convective heat transfer in a differentially heated square enclosure with an inner rotating cylinder is studied theoretically. The free space between the cylinder and the enclosure walls is filled with water- Ag, water-Cu, water-Al 2O 3 or water-TiO 2 nanofluids. The governing equations are formulated for velocity, pressure and temperature formulation and are modeled in COMSOL, a partial differential equation (PDE) solver based on the Galerkin finite element method (GFEM). The governing parameters considered are the solid volume fraction, 0.0 ≤ φ ≤ 0.05, the cylinder radius, 0 ≤ ω ≤ 0.3 and the angular rotational velocity, -1000 ≤ ω ≤ 1000. The results are presented to show the effect of these parameters on the heat transfer and fluid flow characteristics. It is found that the strength of the flow circulation is much stronger for a higher nanoparticle concentration, a better thermal conductivity value and a smaller cylinder with a faster, negative rotation. The maximum heat transfer are obtained at a high nanoparticle concentration with a good conductivity value, a slow positive rotation and a moderate cylinder size located in the center of the enclosure. © 2012 Elsevier Ltd. All rights reserved.

Ahmad N.S.,Ministry of Health Malaysia | Islahudin F.,National University of Malaysia | Paraidathathu T.,National University of Malaysia
Journal of Diabetes Investigation | Year: 2014

Aims/Introduction: The aim of the present study was to determine the status of glycemic control and identify factors associated with good glycemic control among diabetic patients treated at primary health clinics. Materials and Methods: A systematic random sample of 557 patients was selected from seven clinics in the Hulu Langat District. Data were collected from patients' medication records, glycemic control tests and structured questionnaires. Logistic regression analysis was carried out to predict factors associated with good glycemic control. Results: Variables associated with good glycemic control included age (odds ratio 1.033; 95% confidence interval 1.008-1.059) and duration of diabetes mellitus (odds ratio 0.948; 95% confidence interval 0.909-0.989). Compared with the patients who were receiving a combination of insulin and oral antidiabetics, those receiving monotherapy (odds ratio 4.797; 95% confidence interval 1.992-11.552) and a combination of oral antidiabetics (odds ratio 2.334; 95% confidence interval 1.018-5.353) were more likely to have good glycemic control. In the present study, the proportion of patients with good glycemic control was lower than that in other published studies. Older patients with a shorter duration of diabetes who were receiving monotherapy showed better glycemic control. Conclusions: Although self-management behavior did not appear to influence glycemic control, diabetic patients should be consistently advised to restrict sugar intake, exercise, stop smoking and adhere to medication instructions. Greater effort by healthcare providers in the primary health clinics is warranted to help a greater number of patients achieve good glycemic control. © 2013 The Authors.

Bachok N.,University Putra Malaysia | Ishak A.,National University of Malaysia | Pop I.,Babes - Bolyai University
International Journal of Heat and Mass Transfer | Year: 2012

The boundary layer of an unsteady two-dimensional stagnation-point flow of a nanofluid is further investigated. The similarity equations are solved numerically for three types of nanoparticles, namely copper (Cu), alumina (Al 2O 3), and titania (TiO 2) in the water based fluid with Prandtl number Pr = 6.2. The skin friction coefficient, the local Nusselt number, and the velocity and temperature profiles are presented and discussed. Effects of the solid volume fraction parameter φ on the fluid flow and heat transfer characteristics are thoroughly examined. Interesting observation is that there are dual solutions seen for negative values of the unsteadiness parameter A (decelerating flow with A < 0). © 2012 Elsevier Ltd. All rights reserved.

Ahmed M.J.,National University of Malaysia
Heat and Mass Transfer/Waerme- und Stoffuebertragung | Year: 2012

The kinetics of the catalytic hydrogenation of D-glucose to produce D-sorbitol was studied in a threephase laboratory scale reactor. The hydrogenation reactions were performed on activated charcoal supported platinum catalyst in the temperature range 25-65°C and in a constant pressure of 1 atm. The kinetic data were modeled by zero, first and second-order reaction equations. In the operating regimes studied, the results show that the hydrogenation reaction was of a first order with respect to D-glucose concentration. Also the activation energy of the reaction was determined, and found to be 12.33 kJ mole -1. A set of experiment was carried out to test the deactivation of the catalyst, and the results show that the deactivation is slow with the ability of using the catalyst for several times with a small decrease in product yield. © Springer-Verlag 2011.

Leong K.Y.,University of Malaya | Leong K.Y.,National University of Malaysia | Saidur R.,University of Malaya | Mahlia T.M.I.,University of Malaya | Yau Y.H.,University of Malaya
International Journal of Heat and Mass Transfer | Year: 2012

The emergence of several challenging issues such as climate change, fuel price hike and fuel security have become hot topics around the world. Therefore, introducing highly efficient devices and heat recovery systems are necessary to overcome these challenges. It is reported that a high portion of industrial energy is wasted as flue gas from heating plants, boilers, etc. This study has focused on the application of nanofluids as working fluids in shell and tube heat recovery exchangers in a biomass heating plant. Heat exchanger specification, nanofluid properties and mathematical formulations were taken from the literature to analyze thermal and energy performance of the heat recovery system. It was observed that the convective and overall heat transfer coefficient increased with the application of nanofluids compared to ethylene glycol or water based fluids. It addition, 7.8% of the heat transfer enhancement could be achieved with the addition of 1% copper nanoparticles in ethylene glycol based fluid at a mass flow rate of 26.3 and 116.0 kg/s for flue gas and coolant, respectively. © 2011 Elsevier Ltd. All rights reserved.

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

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

Othman Z.,National University of Malaysia | Eshames H.F.,National University of Malaysia
International Journal of Advancements in Computing Technology | Year: 2012

Any abnormal patterns show in Statistical Process Control charts imply the presence of possible assignable causes and variances that may lead to the process performance deterioration. Therefore, timely detection and recognizer of patterns in control charts are very important in the SPC implementation. This paper presents the performance of five classification methods on a set of large data for anomaly patterns detection in control charts. The control chart dataset has its specific features that need specific data preprocessing procedures. It is crucial and involves a number of stages of data preparation procedures. Firstly, the Principle Component Analysis is employed for similarity measure. Secondly, the Piecewise Aggregate Approximation and Symbolic Aggregate Approximation are used as data representation. The preprocessed data are fitted to the classification algorithms to extract important knowledge. The algorithms are support vector machine, decision tree, MLP networks, RIDOR algorithm and JRip algorithm. Numerical results showed that the JRip algorithm has the best performance compared to the others. It achieved highest detection accuracy about 99.66% and the lowest error rate is 2.987.

Sukor N.,National University of Malaysia
European Journal of Internal Medicine | Year: 2011

Hypertension is a very common disease, leading to significant morbidity with reduction in quality of life. In addition to being a major cause of morbidity and mortality, hypertension places a heavy burden on health care systems, families, and society as a whole. In patients with hypertension, the ability to identify a contributing or secondary cause that is potentially curable or amenable to specific forms of management is of great importance. Endocrine hypertension has emerged as one of the common forms of secondary hypertension. Primary aldosteronism, pheochromocytoma and Cushing's syndrome are among the common causes of endocrine hypertension. The application of new clinical, biochemical, and radiologic approaches has significantly advanced our understanding of the pathophysiology and clinical spectrum of these diseases and improved the management strategies of these challenging conditions. © 2011 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

Jasin B.,National University of Malaysia
Bulletin of the Geological Society of Malaysia | Year: 2010

Perlis has many unique geological resources. It has a rock sequence from Cambrian to Triassic represented by four main formations i.e. the Machinchang, Setul, Kubang Pasu and Chuping Formations. Recently, the Mahang Formation was found at Hulu Pauh. A Tertiary continental deposits was also found at Bukit Arang Beds of Tertiary age. Quarrying activities exposed more geological information, such as the boundary of the rock formations and fossils. The boundary between the Setul and Kubang Pasu Formations can be observed at Guar Sanai and Utan Aji. The boundary between the Mahang and the Kubang Pasu Formations is exposed at Bukit Tuntung. The Setul Formation contains a lot of fossils such as stromatolites, trilobites, graptolites, tentaculites and brachiopods. The Kubang Pasu Formation contains bivalves, corals, brachiopods, cephalopods and trilobites of Early Carboniferous in age. The most important fossil in the Kubang Pasu Formation is the Early Permian Monodiexodina (Foraminifera). This is a cold water form found in the Sibumasu Block which formed the southern part of the Cimmerian block which was attached to the Gondwana during the Carboniferous. Quarrying activities in Perlis are still actively progressing, thus more geological heritage information and geosites are undergoing destruction. Action plan must be taken by the relevant authority to protect and conserve these geosites before it is too late.

Aishvarya S.,National University of Malaysia
Comprehensive psychiatry | Year: 2014

The Reasons For Living Inventory has been shown to have good psychometric properties in Western populations for the past three decades. The present study examined the psychometric properties and factor structure of English and Malay version of the Reasons For Living (RFL) Inventory in a sample of clinical outpatients in Malaysia. The RFL is designed to assess an individual's various reasons for not committing suicide. A total of 483 participants (283 with psychiatric illnesses and 200 with non-psychiatric medical illnesses) completed the RFL and other self-report instruments. Results of the EFA (exploratory factor analysis) and CFA (confirmatory factor analysis) supported the fit for the six-factor oblique model as the best-fitting model. The internal consistency of the RFL was α=.94 and it was found to be high with good concurrent, criterion and discriminative validities. Thus, the RFL is a reliable and valid instrument to measure the various reasons for not committing suicide among psychiatry and medical outpatients in Malaysia. © 2014.

Shamsul N.S.,National University of Malaysia | Kamarudin S.K.,National University of Malaysia | Rahman N.A.,National University of Malaysia | Kofli N.T.,National University of Malaysia
Renewable and Sustainable Energy Reviews | Year: 2014

The depletion of the fossil fuel supply and the environmental pollution caused by fossil fuel combustion have become major worldwide problems. Biomass is a renewable resource that has the potential to replace fossil fuels. One of the valuable biomass products is bio-methanol, which can be used to generate electricity and power for portable applications. This paper discusses the potential of bio-methanol as a renewable resource taking into account the world demand, economic assessment, power density and possible applications. It therefore presents the unique properties of bio-methanol as a potential energy resource. It also discusses the various types of biomass that can be obtained from waste products and the different processes that have been developed for the production of bio-methanol fIn addition, it discusses the current problems facing bio-methanol production and the further technological improvements that are needed to support the future energy requirements. Overall, the yield of bio-methanol depends on the type of process used and the associated kinetic parameters of the conversion process. Catalysts have been used in the thermo-chemical and bio-chemical conversion of carbon dioxide into bio-methanol. Several advanced methods have been recently introduced to enhance the production of methanol, but further research is required before these can be used for large-scale bio-methanol production. © 2014 Elsevier Ltd.

Abdullah S.A.,National University of Malaysia
Journal of Land Use Science | Year: 2014

Forest fragmentation has several phases; thus, the ecological significance of each phase during a particular period of time must be interpreted. To interpret, this study quantifies the magnitude of forest loss and the changes in the temporal pattern of fragmentation in the State of Selangor, peninsular Malaysia. Using the decision tree model of land transformation, five phases of forest fragmentation were identified: perforation, dissection, dissipation, shrinkage and attrition. This analysis showed that the magnitude of forest loss was the highest during the dissipation phase. The patchiness analysis showed that dissipation contributes to the highest environmental uncertainty found for the forest patches. This study can be considered a first step in the exploration of the properties and the behavioural pattern shown by the spatial process of forest fragmentation. © 2014 © 2014 Taylor & Francis.

Sheikholeslami M.,Babol Noshirvani University of Technology | Hashim I.,National University of Malaysia | Soleimani S.,Florida International University
Mathematical Problems in Engineering | Year: 2013

This investigation reports the magnetic field effect on natural convection heat transfer in a curved-shape enclosure. The numerical investigation is carried out using the control volume-based-finite element method (CVFEM). The numerical investigations are performed for various values of Hartmann number and Rayleigh number. The obtained results are depicted in terms of streamlines and isotherms which show the significant effects of Hartmann number on the fluid flow and temperature distribution inside the enclosure. Also, it was found that the Nusselt number decreases with an increase in the Hartmann number. © 2013 M. Sheikholeslami et al.

Juneng L.,National University of Malaysia | Tangang F.T.,National University of Malaysia
Atmospheric Science Letters | Year: 2010

The present study examines the long-term trends of the winter monsoon northeasterly cold surge and Borneo vortex over the South China Sea. There has been a significant increase in the frequency of the Borneo vortex within the study period of 1962-2007. The location of the center of the Borneo vortices has shifted slightly offshore; northward of western Borneo. This could result in less vortex-land interaction and lengthen the life span of the vortices due to less frictional shear and hence increase the vortex days. These changes could be related to the strengthened easterly component of the cold surge winds. Copyright © 2010 Royal Meteorological Society.

Chin C.-Y.,National University of Malaysia | Monack D.M.,Stanford University | Nathan S.,National University of Malaysia | Nathan S.,Malaysia Genome Institute
Immunology | Year: 2012

Diabetes mellitus is a predisposing factor of melioidosis, contributing to higher mortality rates in diabetics infected with Burkholderia pseudomallei. To investigate how diabetes alters the inflammatory response, we established a streptozotocin (STZ) -induced diabetic murine acute-phase melioidosis model. Viable B. pseudomallei cells were consistently detected in the blood, liver and spleen during the 42-hr course of infection but the hyperglycaemic environment did not increase the bacterial burden. However, after 24hr, granulocyte counts increased in response to infection, whereas blood glucose concentrations decreased over the course of infection. A genome-wide expression analysis of the STZ-diabetic murine acute melioidosis liver identified ∼1000 genes whose expression was altered in the STZ-diabetic mice. The STZ-diabetic host transcriptional response was compared with the normoglycaemic host transcriptional response recently reported by our group. The microarray data suggest that the presence of elevated glucose levels impairs the host innate immune system by delaying the identification and recognition of B. pseudomallei surface structures. Consequently, the host is unable to activate the appropriate innate immune response over time, which may explain the increased susceptibility to melioidosis in the STZ-diabetic host. Nevertheless, a general 'alarm signal' of infection as well as defence programmes are still triggered by the STZ-diabetic host, although only 24hr after infection. In summary, this study demonstrates that in the face of a B. pseudomallei acute infection, poor glycaemic control impaired innate responses during the early stages of B. pseudomallei infection, contributing to the increased susceptibility of STZ-induced diabetics to this fatal disease. © 2011 The Authors. Immunology © 2011 Blackwell Publishing Ltd.

Tengku S.A.,National University of Malaysia | Norhayati M.,National University of Malaysia
Tropical Biomedicine | Year: 2011

Entamoeba histolytica, the causative agent of human amoebiasis remains a significant cause of morbidity and mortality in developing countries and is responsible for up to 100,000 deaths worldwide each year. Entamoeba dispar, morphologically indistinguishable from E. histolytica is more common in humans in many parts of the world. Similarly Entamoeba moshkovskii, which was long considered to be a free-living amoeba is also morphologically identical to E. histolytica and E. dispar, and is highly prevalent in some E. histolytica endemic countries. Humans are the host of infection and there would not appear to be other meaningful animal reservoirs of E. histolytica. Entamoeba. histolytica can be present in sewage and contaminated water. The infection is mainly transmitted via ingestion of water or food contaminated by faeces containing E. histolytica cysts. Clinical features of amoebiasis range from asymptomatic colonization to amoebic dysentery and invasive extraintestinal amoebiasis, which is manifested most commonly in the form of abscesses in liver and lungs. The epidemiology of amoebiasis has dramatically changed since the separation of E. histolytica and E. dispar species and the worldwide prevalence of these species has not been estimated until recently. Morever, E. moshkovskii, another morphologically indistinguishable human parasitic Entamoeba was not mentioned or considered as a contributor to the prevalence figures in endemic areas. Amoebiasis is still a major health problem especially in aboriginal settlements and amongst people living in remote area in Malaysia. However, until now there is only one data currently available to indicate the true prevalence and incidence of E. histolytica and E. dispar. Further studies are needed to determine the burden of E. histolytica, E. dispar and E. moshkovskii infections in Malaysia. In the present review, we briefly summarize all methods use in diagnosing Entamoeba species, ranging from microscopic identification to molecular detection such as culture and isoenzyme analysis, antibody detection tests, antigen detection tests, immunochromatographic assays, conventional PCR, real-time PCR and loopmediated isothermal amplification (LAMP).

Abdullah H.,National University of Malaysia | Jalal W.N.W.,National University of Malaysia | Zulfakar M.S.,National University of Malaysia
Journal of Sol-Gel Science and Technology | Year: 2014

The need for miniaturization and weight reduction of GPS patch antennas has prompted the search for new microwave dielectric materials. In this study, a sol-gel method was used to prepare Zn(1-x)MgxAl 2O4 thin films and fabricate GPS patch antennas at a low annealing temperature (700 C). X-ray diffraction (XRD) patterns, field emission scanning electron microscopy images, Fourier transform infrared spectra, and optical band gap analyses confirmed the nanostructure of (Mg/Zn)Al 2O4. The XRD patterns displayed the characteristic peaks of (Mg/Zn)Al2O4 with a face-centered cubic structure. Mg addition decreased the crystallite size, surface morphology, and lattice parameters of the resultant films, evidently affecting their density and dielectric constant (E r ). Based on the material investigated and microwave antenna theory, GPS patch antennas were fabricated using Zn (1-x)MgxAl2O4 and then studied using a PNA series network analyzer. The fabricated patch antennas with different E r ceramics decreased in size from 12.5 to 10.8 cm2. The patch antennas resonated at a frequency of 1.570 GHz and provided a return loss bandwidth between -16.6 and -20.0 dB; their bandwidth also improved from 90 to 255 MHz. The GPS patch antenna fabricated from Zn0.70Mg 0.30Al2O4 showed an excellent combination of return loss (-20.0 dB), small size (10.8 cm2), and wide bandwidth (255 MHz). Therefore, addition of Mg improves antenna performance and decreases the dimensions of the device. © 2013 Springer Science+Business Media New York.

Pudukudy M.,National University of Malaysia | Yaakob Z.,National University of Malaysia
Solid State Sciences | Year: 2014

This article reports the synthesis, characterisation and photocatalytic activity of novel ZnO nanostructures prepared via the thermal decomposition of hydrozincite. Hydrozincites were obtained by the conventional precipitation route using different zinc salts such as acetate, nitrate, chloride and sulphate. The effect of counter ions (CH3COO-, Cl -, NO3 -, and SO4 2-) on the structural, textural, morphological and optical properties was investigated. Various characterisations depicted the active role of counter ions in the properties of ZnO. Hexagonal wurtzite structure of ZnO with fine crystalline size was obvious from the XRD results, irrespective of the counter ions. Electron microscopic images indicated the role of counter ions in the surface and internal morphology of ZnO nanomaterials. Special coral like agglomerated morphology of elongated particles with high porosity was observed for the ZnO prepared from acetate precursor. Spherical, elongated and irregular shaped bigger lumps of ZnO nanoparticles with various novel morphologies were resulted for the sulphate, nitrate and chloride precursors respectively. Highly ordered porous micro disc like morphology was noted for the ZnO samples prepared from the sulphate and nitrate salts. Photoluminescence spectra showed the characteristic blue and green emission bands, depicting the presence of large crystal defects and high oxygen vacancies in the samples. Photocatalytic activity of the as-prepared ZnO catalysts was examined by the degradation of methylene blue under UV light irradiation. Degradation results indicated their substantial activity with respect to the counter ions. ZnO prepared from the acetate precursor showed highest photoactivity due to its high surface area, special morphology and high oxygen vacancies. © 2014 Elsevier Masson SAS. All rights reserved.

Hadwan M.,National University of Malaysia | Hadwan M.,Taiz University | Ayob M.,National University of Malaysia | Sabar N.R.,National University of Malaysia | Qu R.,University of Nottingham
Information Sciences | Year: 2013

Harmony search algorithm (HSA) is a relatively new nature-inspired algorithm. It evolves solutions in the problem search space by mimicking the musical improvisation process in seeking agreeable harmony measured by aesthetic standards. The nurse rostering problem (NRP) is a well-known NP-hard scheduling problem that aims at allocating the required workload to the available staff nurses at healthcare organizations to meet the operational requirements and a range of preferences. This work investigates research issues of the parameter settings in HSA and application of HSA to effectively solve complex NRPs. Due to the well-known fact that most NRPs algorithms are highly problem (or even instance) dependent, the performance of our proposed HSA is evaluated on two sets of very different nurse rostering problems. The first set represents a real world dataset obtained from a large hospital in Malaysia. Experimental results show that our proposed HSA produces better quality rosters for all considered instances than a genetic algorithm (implemented herein). The second is a set of well-known benchmark NRPs which are widely used by researchers in the literature. The proposed HSA obtains good results (and new lower bound for a few instances) when compared to the current state of the art of meta-heuristic algorithms in recent literature. © 2013 Elsevier Inc. All rights reserved.

Shamshirband S.,University of Malaya | Anuar N.B.,University of Malaya | Kiah M.L.M.,University of Malaya | Patel A.,National University of Malaysia | Patel A.,Kingston University
Engineering Applications of Artificial Intelligence | Year: 2013

The deployment of wireless sensor networks and mobile ad-hoc networks in applications such as emergency services, warfare and health monitoring poses the threat of various cyber hazards, intrusions and attacks as a consequence of these networks' openness. Among the most significant research difficulties in such networks safety is intrusion detection, whose target is to distinguish between misuse and abnormal behavior so as to ensure secure, reliable network operations and services. Intrusion detection is best delivered by multi-agent system technologies and advanced computing techniques. To date, diverse soft computing and machine learning techniques in terms of computational intelligence have been utilized to create Intrusion Detection and Prevention Systems (IDPS), yet the literature does not report any state-ofthe-art reviews investigating the performance and consequences of such techniques solving wireless environment intrusion recognition issues as they gain entry into cloud computing. The principal contribution of this paper is a review and categorization of existing IDPS schemes in terms of traditional artificial computational intelligence with a multi-agent support. The significance of the techniques and methodologies and their performance and limitations are additionally analyzed in this study, and the limitations are addressed as challenges to obtain a set of requirements for IDPS in establishing a collaborative-based wireless IDPS (Co-WIDPS) architectural design. It amalgamates a fuzzy reinforcement learning knowledge management by creating a far superior technological platform that is far more accurate in detecting attacks. In conclusion, we elaborate on several key future research topics with the potential to accelerate the progress and deployment of computational intelligence based Co-WIDPSs. © 2013 Elsevier Ltd. All rights reserved.

Baqir M.A.,National University of Malaysia | Choudhury P.K.,National University of Malaysia
Journal of Nanomaterials | Year: 2014

The paper deals with the study of flux density through a newly proposed twisted clad guide containing DB medium. The inner core and the outer clad sections are usual dielectrics, and the introduced twisted windings at the core-clad interface are treated under DB boundary conditions. The pitch angle of twist is supposed to greatly contribute towards the control over the dispersion characteristics of the guide. The eigenvalue equation for the guiding structure is deduced, and the analytical investigations are made to explore the propagation patterns of flux densities corresponding to the sustained low-order hybrid modes under the situation of varying pitch angles. The emphasis has been put on the effects due to the DB twisted pitch on the propagation of energy flux density through the guide. © 2014 M. A. Baqir and P. K. Choudhury.

Dihrab S.S.,National University of Malaysia | Sopian K.,National University of Malaysia
Renewable Energy | Year: 2010

Renewable resources gained more attention in the last two decades due to persisting energy demand coupled with decrease in fossil fuel resources and its environmental effect to the earth. In Iraq, the electric power generated is not enough to meet the power demand of domestic and industrial sectors. In this article, a hybrid system was proposed as a renewable resource of power generation for grid connected applications in three cities in Iraq. The proposed system was simulated using MATLAB solver, in which the input parameters for the solver were the meteorological data for the selected locations and the sizes of PV and wind turbines. Results showed that it is possible for Iraq to use the solar and wind energy to generate enough power for some villages in the desert or rural area. It is also possible to use such a system as a black start source of power during total shutdown time. Results also indicated that the preferred location for this system is in Basrah for both solar and wind energy. © 2009 Elsevier Ltd. All rights reserved.

Daghigh R.,National University of Malaysia | Ruslan M.H.,National University of Malaysia | Sulaiman M.Y.,National University of Malaysia | Sopian K.,National University of Malaysia
Renewable and Sustainable Energy Reviews | Year: 2010

Combining solar energy and heat pump technology is a very attractive concept. It is able to eliminate some difficulties and disadvantages of using solar dryer systems or solely using heat pump drying separately. Solar assisted heat pump drying systems have been studied and applied since the last decades in order to increase the quality of products where low temperature and well-controlled drying conditions are needed. This paper reviewed studies on the advances in solar heat pump drying systems. Results and observation from the studies of solar assisted heat pump dryer systems indicated that for heat sensitive materials; improved quality control, reduced energy consumption, high coefficient of performance and high thermal efficiency of the dryer were achieved. The way forward and future directions in R&D in this field are further research regarding theoretical and experimental analysis as well as for the replacement of conventional solar dryer or heat pump dryer with solar assisted heat pump drying systems and solar assisted chemical and ground source heat pump dryers which should present energy efficient applications of the technologies. © 2010 Elsevier Ltd. All rights reserved.

Basri S.,National University of Malaysia | Kamarudin S.K.,National University of Malaysia | Daud W.R.W.,National University of Malaysia | Yaakub Z.,National University of Malaysia
International Journal of Hydrogen Energy | Year: 2010

Nanotechnology has recently been applied to direct methanol fuel cells (DMFC), one of the most suitable and promising options for portable devices. With characteristics such as low working temperature, high energy-conversion efficiency and low emission of pollutants, DMFCs may help solve the future energy crisis. However, a significant limitation to DMFC includes slow reaction kinetics, which reduces performance and power output. Recently, research has focused on increasing the performance and activity of catalysts. Catalysts composed of small, metallic particles, such as platinum and ruthenium, supported on nanocarbons or metal oxides are widely used in DMFC. Thus, this paper presents an overview of the development of nanocatalysts for DMFC. Particularly, this review focuses on nanocatalyst structure, catalyst support, and challenges in the synthesis of nanocatalyst. This paper also presents computational approaches for theoretical modeling of nanomaterials such as carbon nanotubes (CNT) through molecular dynamic techniques. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

Ullah M.H.,National University of Malaysia | Islam M.T.,National University of Malaysia
Journal of Computational Electronics | Year: 2014

A 0.22λ×0.29λ×0.03λ miniaturized modified circular patch monopole antenna on high permittivity ceramic- Polytetrafluoroethylene (PTFE) composite material substrate is presented. The proposed antenna is designed and investigated using 3D full wave high frequency electromagnetic simulator and fabricated using printed circuit board (PCB) prototyping machine. Impedance bandwidths (Reflection coefficient <-10 dB) of 26.76 % (5.0-6.3 GHz), 5.3 % (9.1-9.6 GHz) and 3.6 % (10.7-11 GHz) have measured. Average gains of 0.9 dBi, 3.68 dBi and 3.63 dBi measured at first, second and third band correspondingly. 87.3 %, 88.5 % and 93.1 % radiation efficiencies have achieved at three resonant frequencies 5.6 GHz, 9.5 GHz and 10.9 GHz respectively. The measured symmetric and nearly consistent radiation pattern makes the proposed antenna suitable for C band and X band applications. In this letter, the effects of dielectric properties of substrate material and design parameters have studied. © 2013 Springer Science+Business Media New York.

Islam M.T.,National University of Malaysia | Azim R.,National University of Malaysia | Mobashsher A.T.,King Abdulaziz University
Progress in Electromagnetics Research | Year: 2012

A compact planar ultra-wideband (UWB) antenna with triple band notch characteristics is proposed in this paper. The antenna consist a rectangular radiating patch, a modi-ed partial ground plane, and has an overall dimension of 30 × 22mm2. Three resonant elements are placed above the ground plane to generate three notch frequency bands separately in the WiMAX, the lower WLAN and the upper WLAN frequency bands. The proposed antennas are successfully simulated, prototyped and measured. E®ects of the key deign parameters on band notch characteristics are also investigated. The realized antenna achieved an operating bandwidth (VSWR ≤ 2) ranges from 2.9 to more than 11 GHz with triple notched bands of 3.26- 3.71 (12.9%), 5.15-5.37 (8.5%), and 5.78-5.95 (2.9%) GHz. Measured °at transfer function and constant group delay within the operating band except notched bands make the proposed antenna suitable for being used in practical UWB applications.

Choudhury P.K.,National University of Malaysia
Progress in Electromagnetics Research | Year: 2012

The paper presents an analytical investigation of three-layer twisted clad liquid crystal fiber in respect of its power propagation characteristics. The fiber under consideration has dielectric non-magnetic materials in its core and inner clad sections, whereas the outermost clad is made of radially anisotropic liquid crystal material. Twist in the fiber is introduced in the form of superfine helical turns at the interface of the core and the inner clad regions with specified values of pitch angle. Results demonstrate large confinement of optical power in the outermost liquid crystal section. Further, the angle of twist is seen to have its pronounced effect on controlling the flow of power as it exhibits the ability of governing the propagation characteristics of the medium. The observed propagation feature is attributed to the radial anisotropy of the liquid crystal outer region as well as the amount of twist introduced, and attracts useful applications of such complex fiber structures in evanescent field optical sensing and other coupling devices primarily used in integrated optics.

Alam M.S.,National University of Malaysia | Islam M.T.,National University of Malaysia | Misran N.,National University of Malaysia
Progress in Electromagnetics Research | Year: 2012

A novel design of an electromagnetic bandgap (EBG) structure based on the uniplanar compact EBG (UCEBG) concept is proposed in this paper. The structure is realized by inserting splitring slots inside two reversely connected rectangular patches, which is known as a splitring slotted electromagnetic bandgap (SRS-EBG) structure. The bandgap properties of the EBG structure are examined by the suspended microstrip line and finite element methods (FEM). The achieved bandgaps have widths of 4.3 (59.31%) and 5.16 GHz (38.88%), which are centered at 7 and 13 GHz, respectively. The SRS-EBG is applied to enhance the performance of a single-element microstrip patch antenna (at 7 GHz) and a two-element array (at 13 GHz) configuration. A wider bandwidth is obtained with a better reflection coefficient level for the single element antenna; a reduction in mutual coupling of more than 20.57 dB is obtained for the array design. In both cases, the gain and radiation characteristics are improved. The results are verified by measuring the fabricated lab prototype, and a comparison with the computed results showed good agreement.

Ullah M.H.,National University of Malaysia | Islam M.T.,National University of Malaysia | Mandeep J.S.,National University of Malaysia
International Journal of Applied Electromagnetics and Mechanics | Year: 2013

A parametric study on three different high dielectric substrate materials for antenna miniaturization is conducted in this paper. The antenna substrates of three different dielectric materials in 2 GHz frequency ranges from 7.5 GHz to 9.5 GHz are investigated. Rectangular microstrip antenna on Aluminium oxide, Rogers RT Duroid 6010 and Silicon substrate is designed at the three resonant frequencies of 8.95 GHz, 8.79 GHz and 8.15 GHz respectively. The antenna is designed and analyzed by using three dimensional full-wave electromagnetic field simulators. The performances of the proposed antenna are analyzed using finite element method formulation within the volumetric region. The overall result shows that, aluminium oxide material substrate performs better in terms of bandwidth, gain and radiation characteristics compare to other two substrate materials. © 2013-IOS Press and the authors. All rights reserved.

Siow K.S.,National University of Malaysia
Journal of Electronic Materials | Year: 2014

Silver (Ag) has been under development for use as interconnect material for power electronics packaging since the late 1980s. Despite its long development history, high thermal and electrical conductivities, and lead-free composition, sintered Ag technology has limited market penetration. This review sets out to explore what is required to make this technology more viable. This review also covers the origin of sintered Ag, the different types and application methods of sintered Ag pastes and laminates, and the long-term reliability of sintered Ag joints. Sintered Ag pastes are classified according to whether pressure is required for sintering and further classified according to their filler sizes. This review discusses the main methods of applying Ag pastes/laminates as die-attach materials and the related processing conditions. The long-term reliability of sintered Ag joints depends on the density of the sintered joint, selection of metallization or plating schemes, types of substrates, substrate roughness, formulation of Ag pastes/laminates, joint configurations (i.e., joint thicknesses and die sizes), and testing conditions. This paper identifies four challenges that must be overcome for the proliferation of sintered Ag technology: changes in materials formulation, the successful navigation of the complex patent landscape, the availability of production and inspection equipment, and the health concerns of Ag nanoparticles. This paper is expected to be useful to materials suppliers and semiconductor companies that are considering this technology for their future packages. © 2014 TMS.

Ghasemi M.,National University of Malaysia | Choudhury P.K.,National University of Malaysia
Journal of Nanophotonics | Year: 2014

Wave propagation in optical mediums greatly depends on the materials of which the guides are composed. Among the other forms of optical mediums, liquid crystals are both inhomogeneous and optically anisotropic in nature, and exhibit strong electro-optic behavior, which allows alternation in their optical properties under the influence of external electrical fields. These features make optical fibers containing liquid crystals greatly useful for fabricating many optical devices for practical applications. As such, the analytical investigation of wave propagation through liquid crystal optical fibers, particularly a three-layer fiber with radially anisotropic liquid crystal material in the outermost clad section, remains interesting. The power confinement in the liquid crystal section of such fibers can be enhanced for these to be efficiently used in optical coupling and/or sensing applications. Furthermore, a control over the dispersion characteristics, and, hence, the confinement of power, in such fibers may be imposed by making the guide even more complex in the form of introducing a conducting sheath helix structure at the core-inner clad interface. © 2014 The Authors.

Yacob N.A.,University Technology of MARA | Ishak A.,National University of Malaysia
Meccanica | Year: 2012

An analysis is carried out for the steady two-dimensional flow of a micropolar fluid over a shrinking sheet in its own plane. The shrinking velocity is assumed to vary linearly with the distance from a fixed point on the sheet. The features of the flow and heat transfer characteristics are analyzed and discussed. It is found that the solution exists only if adequate suction through the permeable sheet is introduced. Moreover, stronger suction is necessary for the solution to exist for a micropolar fluid compared to a classical Newtonian fluid. Dual solutions are obtained for certain suction and material parameters. © 2011 Springer Science+Business Media B.V.

Faruque M.R.I.,National University of Malaysia | Islam M.T.,National University of Malaysia | Misran N.,National University of Malaysia
Progress in Electromagnetics Research | Year: 2012

A new triangular metamaterials (TMMs) is designed for electromagnetic (EM) absorption reduction at microwave frequencies in this paper. The reduction of EM absorption with a new TMMs attachment is investigated in this research. The finite-difference time-domain method with lossy-Drude model is adopted in this investigation. The method of EM reduction is presented and the effects of position, distance, and size of metamaterials are analyzed. TMMs have achieved a 1.0923 W/kg for SAR 1 gm which is 45.44% reduction of the initial SAR value for the case of 1 gm SAR.

Yahya N.A.A.,National University of Malaysia | Abd-Shukor R.,National University of Malaysia
Journal of Superconductivity and Novel Magnetism | Year: 2014

Magnesium oxide powders with average particle size 20 and 40 nm were added into Bi1.6Pb0.4Sr2Ca2Cu 3O10 (Bi,Pb-2223) with nominal composition Bi 1.6Pb0.4Sr2Ca2Cu3O 10(MgO) x (x=0-0.15 wt.%). The transport critical current density (J c) and transition temperature were determined using the four-probe method. The structure and microstructure were examined by X-ray diffraction method and scanning electron microscopy, respectively. The transition temperature and J c increased with nanosized MgO addition. The 20 nm MgO added samples showed a higher J c compared with the 40 nm MgO added samples. J c was higher as size of MgO was closer to the coherence length of the superconductor. These results showed that the size variation of flux pinning center at the nanoscale is important in enhancing J c. © 2013 Springer Science+Business Media New York.

Baqir M.A.,National University of Malaysia | Choudhury P.K.,National University of Malaysia
Journal of Electromagnetic Waves and Applications | Year: 2014

Electromagnetic behavior of twisted clad optical fibers is investigated under the situation of sheath helix of perfect electromagnetic (PEMC) conductor introduced at the core-clad interface. The eigenvalue equation for the structure is deduced by applying suitable boundary conditions, and the dispersion behavior of the fiber is analyzed considering the cases of non-dispersive as well as dispersive core with the sustainment of a few low-order modes. The effect on dispersion properties is observed due to alterations in the pitch angle of helical twists as well as the admittance value of the PEMC material. It has been found that the pitch angle and the admittance values can be properly adjusted to attain the degenerate properties of modes which would find many applications in optics industry. © 2014 Taylor and Francis.

Ismail A.E.,University Tun Hussein Onn Malaysia | Ariffin A.K.,National University of Malaysia | Abdullah S.,National University of Malaysia | Ghazali M.J.,National University of Malaysia
Meccanica | Year: 2012

This paper numerically discusses stress intensity factor (SIF) calculations for surface cracks in round bars subjected to single and combined loadings. Different crack aspect ratios, a/b, ranging from 0.0 to 1.2 and the relative crack depth, a/D, in the range of 0.1 to 0.6 are considered. Since the torsion loading is non-symmetrical, the whole finite element model has been constructed, and the loadings have been remotely applied to the model. The equivalent SIF, F*EQ is then used to combine the individual SIF from the bending or tension with torsion loadings. Then, it is compared with the combined SIF, F*FE obtained numerically using the finite element analysis under similar loadings. It is found that the equivalent SIF method successfully predicts the combined SIF, F*EQ forMode I when compared with F*FE. However, some discrepancies between the results, determined from the two different approaches, occur when FIII is involved. Meanwhile, it is also noted that the F*FE is higher than the F*EQ due to the difference in crack face interactions and deformations. © Springer Science+Business Media B.V. 2011.

Pudukudy M.,National University of Malaysia | Yaakob Z.,National University of Malaysia
Applied Surface Science | Year: 2014

In this article, ZnO nanogranules were synthesised rapidly by the thorough solid state mixing of nitrate precursor with citric acid followed by aging and calcination at two different temperatures of 400 C and 600 C. Here, citric acid played a superior role in the development of porous ZnO nanostructures. The ZnO nanogranules obtained in this way were characterised by different techniques. X-ray diffraction patterns indicated a hexagonal wurtzite structure of ZnO with high crystallinity and nanocrystalline size. Scanning and transmission electron microscopy images indicated the uniformly well separated hexagonal morphology of the ZnO nanoparticles, with granular shape. BET surface area-porosity analysis confirmed the presence of a mesoporous network in both samples, with high surface area and a monomodal pore size distribution. Room temperature Photoluminescence spectra of the samples exhibited characteristic blue and green emission bands in accordance with the calcination temperature. The photocatalytic performance of the ZnO nanogranules was studied using methylene blue degradation and found that the ZnO prepared at 400 C exhibited higher photocatalytic activity due to its high surface area and more oxygen vacancies. High concentrations of several hazardous dye pollutants were effectively degraded, when the solution was passed over 50 mg of ZnO nanogranules under UV-light illumination. © 2013 Elsevier B.V.

Baqir M.A.,National University of Malaysia | Choudhury P.K.,National University of Malaysia
Optik | Year: 2014