| | Abstracts of articles: ASM Sci. J. Vol. 1, No. 1, 2007 | | | 1. Prevention of Ethanol-induced Gastric Mucosal Injury by Ocimum basilicum Seed Extract in Rats A. A. MAHMOOD1*, K. SIDIK1 AND H. M. FOUAD2 1 Department of Molecular Medicine, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia 2 Department of Oral Pathology, Oral Medicine and Priodontology, Faculty of Dentistry, University of Malaya, 50603 Kuala Lumpur, Malaysia * Corresponding author (e-mail: mahmood955@yahoo.com) | | | Ocimum basilicum seed extracts were found to possess significant anti-ulcer activity against ethanol-induced ulceration in experimental animal models. Three groups of adult male rats were used, with each group consisting of six rats. Oral administration of absolute ethanol to rats pre-treated with 10% Tween 20® (Group 1) produced extensive haemorrhagic lesions of the gastric mucosa. Rats orally pre-treated with O. basilicum extract suspended in 10% Tween 20® (Group 2) or cimetidine in 10% Tween 20® (Group 3), 30 min before oral administration of absolute alcohol had significantly reduced (p<0.05) the formation of such lesions compared to Group 1 rats. Histologically, rats pre-treated with O. basilicum extract (Group 2) or cimetidine (Group 3) showed significantly (p<0.05) a marked inhibition or reduction of gastric damage, submucosal oedema and leucocytes infiltration compared to animals pre-treated with 10% Tween 20® (Group 1). | | | 2. New Reaction Kinetic Model Derived from Molecular Dynamics Simulation Data on Non-linearity of Rate Coefficients and Their Relation to Activity Coefficients C. G. JESUDASON1 1 Chemistry Department, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia (e-mail: jesu@um.edu.my) | | | Molecular dynamics reaction simulation showed that the rate constant is not constant over the concentration profile of reactants and products over a fixed temperature regime, and this variation is expressed in terms of the defined reactivity coefficients. The ratio of these coefficients for the forward and backward reactions were found to equal that of the activity coefficient ratio for the product and reactant species. A theory was developed to explain kinetics in general based on these observations. Several other theorems had first to be developed, most striking of all was the inference that the excess Helmholtz free energy was the thermodynamical function which had a direct relation to these activity factors than the Gibbs free energy. The theory is applied to a class of ionic reactions which could not be rationalized using the standard Bjørn-Bjerrum theory of ionic reactions. | | | 3. Simulation Study of Carrier-to-Interference Power Ratio Enhancement in Orthogonal Frequency Division Multiplexing System S. Y. Sharifah1*, F. Norsheila1 AND MULADI1 1 Faculty of Electrical Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia * Corresponding author (e-mail: kamilah@fke.utm.my) | | | Orthogonal Frequency Division Multiplexing (OFDM) is a successful technique in wireless communication systems. Frequency offset in the OFDM system leads to loss of orthogonality among subcarriers which results in the occurrence of intercarrier interference (ICI). To improve the efficiency of bandwidth performance in the ICI self-cancellation scheme, frequency domain partial response signaling (PRS) was investigated. In this study, the integer polynomial partial response coefficients were exploited to enhance carrier-to-interference power ratio (CIR) in the OFDM system. CIR was enhanced up to 4.1 dB to 5 dB when the lengths of PRS polynomial, K was 2 and 5, respectively. | | | 4. Optical Tomography: Real Time Image Reconstruction for Various Flow Regimes in Gravity Flow Conveyor R. Abdul Rahim1*, J. F. Pang1, K. S. Chan1, L. C. LEONG1 AND M. H. Fazalul Rahiman2 1 Process Tomography Research Group, Control and Instrumentation Engineering Department, Faculty of Electrical Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia 2 Department of Mechatronics Engineering, North Engineering College University, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia * Corresponding author (e-mail: ruzairi@.fke.utm.my; ruzairiabdulrahim@yahoo.co.uk) | | | In this study, real-time imaging was monitored for flowing solid particles when various baffles were created to block certain areas of the pipe. The generated flow regimes were full-flow, three-quarter-flow, half-flow and quarter-flow. A vertical pneumatic conveyor was designed to hold a 85 mm inner diameter pipeline. The four projection optical tomography systems used, applied the parallel beam projection approach and use infrared light sources so that the sensor was free of noise from the surrounding visible light source. The two orthogonal and two rectilinear projections were axial, but ideally they should have been in the same layer. The sensor readings could be related to the varying light intensity effects of the dropping particles and were used to provide cross-sectional distribution information for the conveyor. By using computer programming, the information was reconstructed to produce coloured images and concentration was obtained by reference to a colour code. The results obtained from this study showed how imaged flow followed the artificial flow regime. This study could benefit industrial production lines in maintaining the desired flow rates. | | | 5. Purification of Metallurgical Grade Silicon by Acid Leaching V. A. Lashgari1* AND H. Yoozbashizadeh2 1 School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Penang, Malaysia 2 Department of Material Science and Engineering, Centre of Excellence in Advanced Materials, Sharif University of Technology, Tehran, Iran * Corresponding author (e-mail: lashgari_v@hotmail.com) | | | Silicon, as the most important electronic material, has a lot of applications in the electronic industry and this includes the use of silicon in solar cells. One of the solar grade silicon production processes is the use of acid leaching for the removal of metallic impurities from silicon. The main advantage of this process for silicon purification is that it is based on a low temperature process. The purification of metallurgical grade silicon by acid leaching was studied as a function of time, temperature and etching. Based upon experimental results and under optimum conditions, it was possible to remove 41%, 71% and 25% of iron, calcium and aluminum respectively, with the use of aqua regia. | | | 6. Fourth Order Centred Total Variation Diminishing Scheme for Hyperbolic Conservation Laws Y. H. ZAHRAN1 1 Physics and Mathematics Department, Faculty of Engineering, Suez Canal University, Port Said, Port Fouad, P. O. Box 42523, Egypt E-mail : yousef_hashem_zahran@yahoo.com | | | A new fourth order accuracy centred finite difference scheme for the solution of hyperbolic conservation laws is presented. A technique of making the fourth order total variation dimishing (TVD) scheme is also exhibited. The resulting scheme could avoid the spurious oscillations and preserve fourth-order accuracy in smooth parts. In addition the extension of the TVD scheme to the nonlinear scalar hyperbolic conservation laws are discussed. For nonlinear systems the TVD constraint was applied by solving shallow water equations. The performance of the scheme was assessed by solving test problems. Numerical results are presented and compared with exact solutions and other methods. | | | 7. Stability of Marangoni Convection in Superposed Fluid and Porous Layers N. M. Arifin1,*, N. F. M. Mokhtar1, R. Nazar2 AND I. Pop3 1 Department of Mathematics, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor 2 School of Mathematical Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor 3 Faculty of Mathematics, University of Cluj, R-3400 Cluj, CP 253, Romania * Corresponding author (e-mail: norihan@fsas.upm.edu.my) | | | Linear stability analysis was used to investigate the onset of Marangoni convection in a two-layer system. The system comprised a saturated porous layer over which was a layer of the same fluid. The fluid was heated from below and the upper free surface was deformable. At the interface between the fluid and the porous layer, the Beavers-Joseph slip condition was used and in the porous medium the Darcy law was employed to describe the flow. Predictions for the onset of convection were obtained from the analysis by the perturbation technique. The effect of surface deformation and depth ratio, z (which is equal to the depth of the fluid layer/depth of the porous layer) on the onset of fluid motion was studied in detail. | |
