Universiti Putra Malaysia
Download Latest Complete Journal - JST Vol. 23 (2) Jul. 2015
Foreword by the Chief Executive Editor
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Abstract (Viewed: 14)Activin proteins are members of the transforming growth factor-β family. Activin A is involved in several biological responses including wound repair, cell death, proliferation and differentiation of many cell types. Biologically active activins consist of homodimers or heterodimers of two beta (β) subunits that are linked together by a single covalent disulphide bond. The subunits in humans are βA, βB, βC and βE. As an example, a combination of two βA subunits will produce a unit of activin A. These proteins are found in most cells of body such as macrophage and activated circulating monocytes. Their role in inflammation can be categorised into two types, either pro- or anti-inflammatory agents, depending on the cell type and phase. Activin signals are kept in balance by antagonist follistatin (Fst), which is a glycoprotein expressed in tissues and encoded by the follistatin gene in humans.Activin, transforming growth factor, activin subunit, inflammation, follistatin.
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Abstract (Viewed: 9)This paper presents an overview topic of layered and laminated fibre composites. The review presents an investigation on the effect of varying the properties of fibre and the matrix of layered and laminated composites and identifies the fundamental parameters determining ballistic impact protection. The advantages of layered and laminated reinforced composites with different thicknesses for further enhancing ballistic penetration resistance of the laminated fibre composite have been reviewed. amination of multiple layers of composite material can give better ballistic performance.Layer, laminate, ballistic impact, composites
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Abstract (Viewed: 8)A shift to administration of optimal dose of 18F-FDG between 4 and 5 MBq/kg from the current practice of higher doses potentially yields a reasonable-to-excellent PET image. For this purpose, whole-body MIP images of 32 patients (23 men, 9 women, age 51.9 ± 13.7 years), administered with 18F-FDG(activity 5.3 ± 0.5 MBq/kg, 45 minutes uptake time) for whole-body PET/CT examinations, were evaluated. Image quality was assessed visually by two radiologists using a three-point scoring scale: poor, reasonable and excellent. The interobserver agreement revealed a kappa value higher than 0.7. Therefore, the utilisation of 18F-FDG dose between 4 and 5MBq/kg is considered an optimum dose for whole-body PET/CT examination.18F-FDG, PET/CT, PET image quality, optimum dose, administered dose/body weight (kg), MIP
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Abstract (Viewed: 51)Sludge is an unavoidable product of wastewater treatment that creates problems of disposal. Increasingly, strict environmental control regulations have resulted in limitations on sludge disposal options.Disposal by incineration has been found to be a good option. In this research, application of domestic waste sludge powder (DWSP) was used as cement replacement in concrete mix. This study utilised replacement of 3 %, 5 %, 7 %, 10 % and 15 % by weight of OPC with water binder (w/b) ratio of 0.60, 0.55 and 0.40 for Grade 30, Grade 40 and Grade 50 respectively. The performance of DWSP concrete in terms of its compressive strength, water absorption, water permeability and Rapid Chloride Ion penetration were investigated. All values of compressive strength for DWSP concrete were lower compared to the OPC control, and the strength decreased as the percentage of replacement with DWSP increased for Grade 30 and Grade 50, except for Grade 40 at replacement of 7 %. Meanwhile, water absorption and water permeability for the DWSP concrete increased as the replacement increased. Overall, with further research in producing quality DWSP, the potential of using this waste as a cement replacement material is very promising.Domestic Waste Sludge Powder, compressive strength, water absorption, water permeability, Rapid chloride Ion penetration
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Abstract (Viewed: 3)The objective of this study was to explore the geographic distribution and temporal patterns of violent crime cases in Peninsular Malaysia by using the tools and techniques for spatial analysis. This study will also provide a general picture of violent crime patterns in Malaysia. The unit of analysis is district and the violent crime data from the year 2000 until 2009 were used in this study. In order to obtain the optimum number of components of crime in the space-time period, the space-time Normal Mixture Models were used. Based on the results of this model, the mapping of the crime occurrences was made. This map displays the spatial distribution of crime occurrence in 82 districts of Peninsular Malaysia. From this analysis, more violent crimes were shown to have occurred in developed states such as Selangor, Wilayah Persekutuan Kuala Lumpur and Johor. The findings of this study could be used by policy makers or responsible agencies to take any relevant actions in terms of crime prevention, human resource allocation and law enforcement so as to overcome this important issue in future.Violent crime, normal mixture, model mapping
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Abstract (Viewed: 8)This paper evaluates the performance measures indicated by the Highway Capacity Manual (HCM) to assess the level of service (LOS) on two-lane highways under heterogeneous traffic conditions. The study is based on field observations and, accordingly, traffic data were collected on a two-lane National Highway in India. The measures, percent time-spent-following (PTSF) and average travel speed (ATS) were estimated using easily collectible field data considering both two-way and directional segments. The actual PTSF values were observed to be lower than the expected values. This lack of conformity is probably because of drivers' impatience that increases with the platoon length and delay. The ATS was also measured in the field and compared to those obtained using HCM. ATS was observed to be insensitive to flow in mixed traffic situations because of frequent platoon formation. In addition, a direct assessment of LOS in the field indicates over-prediction, which is attributed to the presence of a sizable proportion of slower vehicles based on users' opinion poll.Average travel speed, heterogeneous traffic flow; level of service, percent time-spent following, platooning, two-lane highways
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Abstract (Viewed: 5)A numerical simulation and analysis was performed to investigate the effect of absorber and buffer layer band gap grading and on a Copper-Indium-Gallium-Diselenide (CIGS) solar cell. The software used is the Solar Cell Capacitance Simulator (SCAPS). The absorber and buffer layer energy band structures' effect on the cell's output parameters such as open circuit voltage, short circuit current density, fill factor and efficiency were extensively simulated. Two structures of the energy band gap were simulated and studied for each of the absorber and buffer layer. The simulation was done on the uniform structure in which the energy band gap is constant throughout the layer. It was then continued on the cell with graded band structure, where the energy band gap of the material is varied throughout the layer. It was found that the cell with graded band structure in absorber and buffer layer had demonstrated higher efficiency and better performance in comparison with the cell with uniform band gap structure.Band gap, CIGS absorber, Grading, SCAPS
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Abstract (Viewed: 6)Many studies have been carried out using different metaheuristic algorithms on optimisation problems in various fields like engineering design, economics and routes planning. In the real world, resources and time are scarce. Thus the goals of optimisation algorithms are to optimise these available resources. Different metaheuristic algorithms are available. The firefly algorithm is one of the recent metaheuristic algorithms that is used in many applications; it is also modified and hybridised to improve its performance. In this paper, we compare the Standard Firefly Algorithm, the Elitist Firefly Algorithm, also called the Modified Firefly Algorithm with the Chaotic Firefly Algorithm, which embeds chaos maps in the Standard Firefly Algorithm. The Modified Firefly Algorithm differs from the Standard Firefly Algorithm in such a way that the global optimum solution at a particular iteration will not move randomly but in a direction that is chosen from randomly generated directions that can improve its performance. If none of these directions improves its performance, then the algorithm will not be updated. On the other hand, the Chaotic Firefly Algorithm tunes the parameters of the algorithms for the purpose of increasing the global search mobility i.e. to improve the attractiveness of fireflies. In our study, we found that the Chaotic Firefly Algorithms using three different chaotic maps do not perform as well as the Modified Firefly Algorithms; however, at least one or two of the Chaotic Firefly Algorithms outperform the Standard Firefly Algorithm under the given accuracy and efficiency tests.Metaheuristic, optimisation, Standard Firefly Algorithm, Modified Firefly Algorithm, Chaotic Firefly Algorithm
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Abstract (Viewed: 4)Continuous professional development (CPD) has gained prominence in the last decade to meet improved self-development and health care services among health professionals. Being practitioners serving clients in health care, therefore, necessitates the importance of the physiotherapist's participation in activities of CPD. This paper aims to identify how physiotherapists view CPD, barriers to its progress and its impact on healthcare practice. This is a qualitative study with one-to-one interview sessions involving open-ended questions to facilitate free flow of idea that are rich with information. Twenty-two physiotherapist (17 females and 5 males) participated. Four main themes were generated following analysis: (i) comprehension of what is CPD (ii) outcome of CPD (iii) barriers to undertaking CPD and (iv) strategies to improve participation in CPD. Further sub-themes were generated from the themes suggestive of physiotherapists' awareness and concerns related to CPD activities and problems encountered when embarking on CPD participation. In conclusion, physiotherapists should recognise the importance of participation in CPD activities either for self-development or to provide effective health care services. The main barrier to CPD activities that was identified was a support system that facilitates enhancement in such activities. This has major implication such as mandatory participation in CPD among staff and for managers to ensure that an effective mechanism is in place such as funding, schedule events and moral support.Barriers, continuous professional development, clinical competency, perception, physiotherapist, strategies
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Abstract (Viewed: 6)Quercus infectoria gall, which is known as manjakani in Malaysia, was traditionally used in treating diseases. The bioactive compounds from the galls can be extracted using various extraction methods. In this study, supercritical carbon dioxide (SC-CO2) extraction was used to study the effects of CO2 flow rate on the yield, total phenolic content and antioxidant activity of Q. infectoria extract by fixing the pressure and temperature at the highest density (P: 30 MPa, T: 40°C). The results were compared with those acquired from the Soxhlet extraction method. The results showed that the Soxhlet extraction had a higher percentage of extraction yield than SC-CO2 extraction. The selectivity of Q. infectoria extracts using SC-CO2 extraction was better than the Soxhlet extraction method. Meanwhile, the extraction efficiency using the SC-CO2 extraction ranged from 46% to 53%. The SC-CO2 extraction also yielded higher total phenolic content than using the Soxhlet extraction method when 2 mL/min of CO2 flow rate was applied (203.53 mg GA/g sample). This study also revealed that the extracts from the SC-CO2 extraction showed a better radical scavenging activity compared to the Soxhlet extraction when analysed using DPPH (2,2-diphenyl-1-picryl hydrazyl) radical scavenging activity assays.radical scavenging activity compared to the Soxhlet extraction when analysed using DPPH (2,2-diphenyl-1-picryl hydrazyl) radical scavenging activity assays.Quercus infectoria, radical scavenging, activity, Soxhlet extraction, supercritical carbon dioxide extraction, radical scavenging activity, total phenolic content
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Abstract (Viewed: 6)Field investigation on the operation of an industrial fluidized bed paddy dryer of 25 t/h capacity available in a processing complex of Padiberas Nasional Berhad (BERNAS) of Malaysia was carried out to assess its drying characteristics, energy consumption and quality of product during two paddy harvesting seasons. A grain drying simulation model was used to predict dryer performance which can be used as a basis for improving drying operations. For the first season (August-September), average drying rate was found to be 538 kg moisture/h to reduce moisture content (mc) from 36.98± 0.89% dry basis (db) to 27.58±0.79% (db) at 100-120°C of drying air temperature with a feed rate (capacity) of 7.75 t/h. In the second season (February-March), average drying rate was found to be 435 kg moisture/h to reduce mc from 28.14 ±0.68% (db) to 22.54 ± 0.69% (db) at 78-90°C drying air temperature with a feed rate of 9.5 t/h. The thermal and electrical energy consumptions were obtained as 7.57 and 0.97 MJ/kg water removed, respectively, for the first season, while 5.92 and 1.2 MJ/kg water removed for the second season. Higher head rice yield and whiteness and lower milling recovery were achieved during the first season than the second season at acceptable milling degree and transparency. Meanwhile, simulation results indicated that the dryer performed better in terms of increased drying capacity during the second than the first season; the dryer could be operated at 150°C to achieve almost double throughput capacity up to 20 t/h for the second season, while for the first season, high mc hindered the capacity to be at or below 7.75 t/h even when using higher a temperature of 160°C to reduce moisture to the desired final moisture of 24-25% (db). Proportion of slower vehicles based on users' opinion poll.Drying simulation, drying rate, industrial fluidized bed paddy dryer, milling quality, energy consumption, head rice yield, drying performance
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Abstract (Viewed: 7)This work describes the effects of different cooking temperatures in repetitive cooking-chilling (RCC) process on resistant starch (RS) content in fish crackers prepared in a ratio of 1:1 fish to sago starch formulation. In this work, three sets of four RCC cycles were performed on fish crackers, in which each set was cooked at fixed temperatures of 100, 115 and 121°C, respectively. The chilling temperature was fixed at 4°C in all cases. Subjecting the fish crackers to a higher cooking temperature for up to 4 cycles of RCC can increase the RS content. However, quality degradation was observed in the characteristics of the fish crackers. During the first RCC cycle, cooking at a higher temperature had caused the crackers to crack and burst. Besides, defragmentation to the shape of the fish cracker gels was also observed during the first RCC cycle, coupled with softer texture and high moisture content. When the products were subjected to frying, their linear expansion decreased, the texture became harder and the colour turned darker. This work demonstrated that the application of higher cooking temperature up to 4 RCC cycles was able to enhance the RS content in the fish crackers, but it was less able to attain the product's perfect shape. On the contrary, fish crackers that were exposed to lower cooking temperatures contained lower RS but with less shape damage.Resistant starch, fish cracker, cooking, chilling, temperature
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Abstract (Viewed: 7)The objective of this study was to evaluate the effects of milling methods on tensile properties of polypropylene (PP) / oil palm mesocarp fibre (OPMF) biocomposites. Two types of mills were used; Wiley mill (WM) and disc mill (DM). Ground OPMF from each milling process was examined for its particle size distribution and aspect ratio by sieve and microscopic analyses, respectively. Results showed that DM-OPMF had smaller diameter fibre with uniform particle size compared to the WM-OPMF. Surface morphology study by SEM showed that DM-OPMF had rougher surface compared to WM-OPMF. Furthermore, it was found that PP/DM-OPMF biocomposite had higher tensile strength compared to PP/WM-OPMF, with almost two-fold. Thus, it is suggested that small diameter and uniform size fibre may improve stress transfer and surface contact between the fibre and polymer matrix and cause well dispersion of filler throughout the polymer resulted in better tensile strength of PP/DM-OPMF Compared to PP/WM-OPMF biocomposite. Overall, it can be concluded that disc milling could serve as a simple and effective grinding method for improving the tensile properties of biocomposite.Biocomposite, disc mill, oil palm mesocarp fiber, polypropylene, tensile properties, Wiley mill.
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Abstract (Viewed: 6)The presence of airflow during heating process is expected to increase heat uniformity in a closed heating chamber. Circulation of hot air increases the percentage of convective heat transfer. In this study effects of airflow on oven temperature, cake temperature and several cake qualities were investigated. Experimental studies were conducted in convective oven using two different baking modes; with and without airflow. During baking, oven temperatures and internal cake temperature were measured, and images of cake expansion were captured. Results of the study showed that the presence of airflow could maintain the oven temperature within a small range of set point temperature. Temperature in the oven exhibited ±5.5°C fluctuation, approximately 3.5% overshoot that occurred continuously during baking with airflow. On the contrary, higher overshoot (ranging from 15 to 30%) was observed in oven temperature without airflow. Airflow also showed a significant effect (p<0.01) during the second stage of baking. The presence of airflow increased the heating rate and resulted in a faster volume expansion, which was 3.21mm/min, as compared to 2.88mm/min without the airflow. However, airflow dried off the cake surface, resulted in quicker browning, higher weight loss and lower moisture content of cakes.Cake baking, airflow, heat transfer, internal cake temperature, volume expansion
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Abstract (Viewed: 8)Effects of different types of solvent on the antioxidant and antibacterial activity of Quercus infectoria extract have not been well documented. Therefore, extraction process was conducted using conventional Soxhlet extraction with six different types of solvent (100% methanol, ethanol, acetone, water and 70% methanol, and ethanol). High performance liquid chromatography was implemented to identify gallic acid and tannic acid in the extracts. Water extracts contained the highest concentration of both gallic acid and tannic acid compared to other types of solvent; 51.14 mg/g sample and 1332.88 mg/g sample of gallic acid and tannic acid. Meanwhile, antioxidant and antibacterial activity were tested using DPPH free radicals scavenging and disc diffusion assay. Results demonstrated that water extracts gave the highest antioxidant activity (approximately 94.55%), while acetone extract gave the largest inhibition zone for disc diffusion assay (19.00mm respectively). The results also revealed rich sources of gallic acid and tannic acid in Q. infectoria which might provide a novel source of these natural antioxidant and antibacterial activity.Bioactive compound, solvent, antioxidant activity, antibacterial activity, gallic acid, HPLC, tannic acid, and Q. infectoria.

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