Investigation of the effect of charge transfer coefficient (CTC) on the operating voltage of polymer electrolyte membrane (PEM) electrolyzer

Activation overpotential is a very important parameter in evaluating the performance of PEM electrolyzer, it is one of the major overpotentials that contribute towards overall operating voltage of the electrolyzer. One of the most significant parameters associated with this overvoltage is charge transfer coefficient (CTC). This study aims to contribute to this growing area of research by investigating the effects of operating temperature and CTC on the overall operating voltage. This study also provides an important opportunity to advance the understanding of the effect of different temperature and pressure on the CTC. The result of this study was successfully compared with experimental data. The simulation result shows that, within the temperature range of 10 °C–90 °C, the CTC values at the anode electrode ranges between 0.807 and 1.035 while at the cathode electrode, the variation is only within 0.202–0.259. It was observed that activation overvoltage decreases when the CTC increase from 0.1 to 2.0 both at anode and cathode electrodes. Interestingly it was observed that the CTC remains the same even at balanced and unbalanced pressure.     

Optimization of the Strength Properties of Waste Oil Palm (Elaeis Guineensis) Fronds Fiber

In this study, Box-Behnken design (BBD) and response surface methodology (RSM) was applied to study the effects of alkaline peroxide treatment variables (cooking time, sodium hydroxide concentrations, and hydrogen peroxide concentrations) on the pulp and paper strength properties (screened pulp yield, kappa number, tensile index, tear index, burst index), which are considered dependent variables or response variable of the extracted cellulose from oil palm (Elaeisguineensis) fronds (OPF) vascular bundle fibers. The results indicated that at the optimum operating conditions of 2.35% NaOH, 5.00% H₂O₂ and a 53.41 min cooking time, resulting maximum strength properties (tensile index, burst index, tear index,) gave 9.92 Nm/g, 6.55 KPam²/g, 6.22 mNm²/g, respectively. The study revealed that alkaline peroxide pulped fibers of oil palm frond vascular bundles could be considered a suitable alternative for paper qualities with moderate strength requirements.     

Simultaneous detection of Salmonella spp., Salmonella Typhi and Salmonella Typhimurium in sliced fruits using multiplex PCR

This study aimed to determine the prevalence and quantity of Salmonella spp., Salmonella Typhi and Salmonella Typhimurium in sliced fruits from hawker stalls and hypermarkets in Malaysia. Analysis was carried out using the most probable number (MPN) – multiplex polymerase chain reaction (PCR) method. The prevalence of Salmonella spp., Salmonella Typhi and Salmonella Typhimurium in 210 samples of sliced fruits examined were 23.3%, 7.6% and 3.8%, respectively with estimated quantity varying from 0 to 19 MPN/g. This study urged the authority to look into the biosafety of sliced fruits in Malaysia.     

Lard uptake and its detection in selected food products deep-fried in lard

Analytical methods for the detection of both pork and lard in food products are in great demand for regulatory purposes. Means of identifying food products fried in lard has been investigated in this study. Four fat containing products namely, peanuts, tempeh (fermented soybean cake), chicken and beef were subjected to deep-fat frying using lard as the frying medium. Oils extracted from the control and fried samples were analyzed by gas liquid chromatography (GLC), high performance liquid chromatography (HPLC) and differential scanning calorimetry (DSC). In this way, changes in composition and thermal profiles during frying were examined. Results showed that palmitic acid enrichment factor (PAEF) calculated from GLC analysis of fatty acid methyl esters seems to be a useful parameter in determining lard contamination in all four fried products. With the triglycerol (TG) profiling by HPLC it was possible to detect lard in fried chicken and tempeh products while DSC cooling and heating traces were found to be useful for lard detection in fried tempeh, chicken and beef products.     

Application of MPN-PCR in biosafety of Bacillus cereus s.l. for ready-to-eat cereals

Since Bacillus cereus is one of the important foodborne pathogens, it is interesting to investigate the biosafety of Bacillus spp. and B. cereus in ready-to-eat cereals marketed local supermarkets. For this investigation, the prevalence and enumeration of Bacillus spp. and B. cereus were assayed using MPN-PCR method. Results showed that 78% of the processed cereal products intended for direct consumption were positive for the presence of B. cereus with concentrations ranging from as low as 30 MPN/g to more than 24,000 MPN/g. The concentration obtained from this study also reflects on the differences in the contamination level between the infant food, raw cereals, cereal bars, ready-to-eat breakfast cereals and pre-mixed drinks examined. Hence, application of the MPN-PCR method was found to be useful to address the biosafety concerns of B. cereus in ready-to-eat cereals.     

Nonlinear optical processes in optically trapped InP nanowires

We report on the observation of nonlinear optical excitation and related photoluminescence from single InP semiconductor nanowires held in suspension using a gradient force optical tweezers. Photoexcitation of free carriers is achieved through absorption of infrared (1.17 eV) photons from the trapping source via a combination of two- and three-photon processes. This was confirmed by power-dependent photoluminescence measurements. Marked differences in spectral features are noted between nonlinear optical excitation and direct excitation and are related to band-filling effects. Direct observation of second harmonic generation in trapped InP nanowires confirms the presence of nonlinear optical processes.