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Muhammad Sani Usman,1 Mohamed Ezzat El Zowalaty,2,5 Kamyar Shameli,1,3 Norhazlin Zainuddin,1 Mohamed Salama,4 Nor Azowa Ibrahim1 1Department of Chemistry, Faculty of Science, 2Laboratory of Vaccines and Immunotherapeutics, Institute of Bioscience, Universiti Putra Malaysia, Selangor, Malaysia; 3Materials and Energy, Research Center, Karaj, Iran; 4Faculty of Pharmacy, UiTM, Puncak Alam, Selangor, Malaysia; 5Department of Environmental Health, Faculty of Public Health and Tropical Medicine, Jazan University, Jazan, Kingdom of Saudi Arabia Abstract: Copper nanoparticle synthesis has been gaining attention due to its availability. However, factors such as agglomeration and rapid oxidation have made it a difficult research area. In the present work, pure copper nanoparticles were prepared in the presence of a chitosan stabilizer through chemical means. The purity of the nanoparticles was authenticated using different characterization techniques, including ultraviolet visible spectroscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and field emission scanning electron microscopy. The antibacterial as well as antifungal activity of the nanoparticles were investigated using several microorganisms of interest, including methicillin-resistant Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Salmonella choleraesuis, and Candida albicans. The effect of a chitosan medium on growth of the microorganism was studied, and this was found to influence growth rate. The size of the copper nanoparticles obtained was in the range of 2–350 nm, depending on the concentration of the chitosan stabilizer. Keywords: chitosan, copper nanoparticles, antimicrobial activity, chemical synthesis, aqueous medium

This research study on leakage and flashover currents in silicone rubber treated with coal dust (fly ash) pollutants with variations in the duration of impurity conditioning within 1, 2, 3 days, and no conditioning. This research prepares for testing the RTV 497 silicone rubber test sample which is formed into a sheet with a thickness of 1 mm while the length and width are 50 x 25 mm which is attached with a leaf-like sample electrode system which is designed using the sketch up application with the number of samples of each 5 pieces each for each variation of conditioning carried out, then tested using an Aluminum Tape electrode system with a gap between the Aluminum Tape electrodes of 5 mm. To determine the value of the leakage current that passes through the surface of the Silicone Rubber, voltages of 220 V, 500 V, and 1000 V are applied, left for 1 minute for each voltage application variation to read the value of the current flowing on the sample surface, then the voltage is increased slowly until flashover occurs. The test results showed a leakage current value of 1, 2, and 3 days without conditioning when applying a voltage of 220 V is 34.53; 34.69; 34.81; and 35.09 mA, the same for application at a voltage of 500; and 1000 V that is the leakage current value increases. This is for any current flowing from the conductor to the ground to pass through the outer surface of the insulator. If the surface of the insulator has a layer of contaminants, it can affect the leakage current that flows on the surface. Meanwhile, the flashover test results with the same sample obtained a value of 4112.8; 3819.4; 3676.4; and 3511 V, the data obtained is that the voltage decreases with the longer the conditioning time is carried out since dust contaminants tend to settle and stick to the insulator, which is one of the biggest causes of flashover and failure.

This study concerns with the production and partial characterization of alkaline cellulase from alkaliphilic cellulolytic (AC) fungi isolated fromsoil in Perlis, Malaysia. The best fungi strain was selected on the basis of producing the highest cellulase at high pH conditions. Cellulase from the selected fungi strain was further characterized under saccharification but varies in operating parameters. Finally, the kinetic model describing the growth of the AC fungi strain was studied by employing the logistic model. Among the tested fungi strains, Basidiomycetes strain (BK1) showed high potentiality for the production of maximum alkaline cellulase production at pH 9 after 72 h of incubation at 30°C containing 6 g·L−1 carboxyl methyl cellulose. The saccharification process showed that the enzyme favour high alkaline condition and proves thermotolerant properties, while 15% (v/v) enzyme loading and 1% substrate concentration recorded the highest glucose production at about 1.2–1.3 mg·mL−1. The novelty of the study is to identify and optimize a unique indigenous fungi that emit alkaliphilic cellulase as alternative usage in biotechnology industries due to its capacity to adapt to the extreme conditions of specific industrial processes. There are revolutionary options for use in biotechnological businesses that involve high pH and therefore have substantial biotechnological promise.

Many initial value problems are difficult to be solved using ordinary, explicit step-by-step methods because most of these problems are considered stiff. Certain implicit methods, however, are capable of solving stiff ordinary differential equations (ODEs) usually found in most applied problems. This study aims to develop a new numerical method, namely the high order variable step variable order block backward differentiation formula (VSVO-HOBBDF) for the main purpose of approximating the solutions of third order ODEs. The computational work of the VSVO-HOBBDF method was carried out using the strategy of varying the step size and order in a single code. The order of the proposed method was then discussed in detail. The advancement of this strategy is intended to enhance the efficiency of the proposed method to approximate solutions effectively. In order to confirm the efficiency of the VSVO-HOBBDF method over the two ODE solvers in MATLAB, particularly ode15s and ode23s, a numerical experiment was conducted on a set of stiff problems. The numerical results prove that for this particular set of problem, the use of the proposed method is more efficient than the comparable methods. VSVO-HOBBDF method is thus recommended as a reliable alternative solver for the third order ODEs. [ABSTRACT FROM AUTHOR]

This was a cross-sectional study to identify the association between socio-cognitive factors (permissive attitude, social-norms, and self-efficacy) and intention towards sexual activity among 466 Malaysian school-going late adolescents (aged 18–19 years) in Kuantan, Malaysia. Majority were females (64.4%), Malays (67.4%) and Muslims (68.2%). Simple logistic regression from data collected by self-administered validated Youth Sexual-Intention Questionnaire (YSI-Q) showed significantly increase risk of having sexual intention for each unit increase in permissive attitude, social-norms and self-efficacy scores with the odds ratio (OR) of 1.424, 1.303 and 1.215, respectively. On the other hand, multivariate logistic regression resulted in male, non-Malay, ever-smoker students and permissive attitude showing significantly higher risk towards having sexual intention with the OR of 0.163 (male was the reference group), 5.110, 3.288 and 1.236, respectively. In order to reduce risky sexual behaviour among adolescents, school-based health education is essential. [ABSTRACT FROM AUTHOR]