Solid polymeric electrolyte of PVC–ENR–LiClO<Subscript>4</Subscript>

The ionic conductivity of PVC–ENR–LiClO₄ (PVC, polyvinyl chloride; ENR, epoxidized natural rubber) as a function of LiClO₄ concentration, ENR concentration, temperature, and radiation dose of electron beam cross-linking has been studied. The electrolyte samples were prepared by solution casting technique. Their ionic conductivities were measured using the impedance spectroscopy technique. It was observed that the relationship between the concentration of salt, as well as temperature, and conductivity were linear. The electrolyte conductivity increases with ENR concentration. This relationship was discussed using the number of charge carrier theory. The conductivity–temperature behaviour of the electrolyte is Arrhenian. The conductivity also varies with the radiation dose of the electron beam cross-linking. The highest room temperature conductivity of the electrolyte of 8.5 × 10⁻⁷ S/cm was obtained at 30% by weight of LiClO₄. The activation energy, E _a and pre-exponential factor, σ _o, are 1.4 × 10⁻² eV and 1.5 × 10⁻¹¹ S/cm, respectively.     

Morphology and optical investigations of ZnO pyramids and nanoflakes for optoelectronic applications

Zinc-oxide (ZnO) pyramidal and nanoflakes were grown by electrochemical deposition of Zn(NO₃)₂·6H₂O on n-type Si substrate with different crystallographic orientations and on indium tin oxide (ITO)-coated glass. Various morphological shapes of deposited ZnO nanostructures were observed, which were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The bulk modulus was calculated to determine the material stiffness. Two peaks were observed at room temperature photoluminescence spectrum, i.e., a near-band-edge (NBE) emission in the UV region and a broad deep-level emission (DLE) in the green emission region. The optical properties were calculated to confirm the specific models validity of ZnO nanostructures for optoelectronics. The measured and calculated values show good agreement with other data.     

Transportation in a lithium-ion half-cell

In order to understand the transportation processes in a lithium-ion half-cell during discharge, the concentration profile of lithium-ion in the solution phase is considered. In this paper, the concentration model is solved using finite difference method (FDM). This numerical method is selected and finally compared with one of the analytical methods, that is, separation of variable (SOV). From this comparison, the error is achieved between the FDM and the SOV. The agreement between obtained and published results is verified by root mean square error.     

Thin film flow and heat transfer on an unsteady stretching sheet with internal heating

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.     

Triterpene composition and bioactivities of Centella asiatica

Leaves of Centella asiatica (Centella) were analysed for their triterpene composition and bioactivity such as collagen enhancement, antioxidant, anticellulite and UV protection capacity properties. Triterpenes of Centella were measured using HPLC-PAD on an Excil ODS 5 mm (C18) column for the simultaneous determination of asiatic acid, madecassic acid, asiaticoside and madecassoside. Centella was found to contain significant amounts of madecassoside (3.10 ± 4.58 mg/mL) and asiaticoside (1.97 ± 2.65 mg/mL), but was low in asiatic and madecassic acid. The highest collagen synthesis was found at 50 mg/mL of Centella extracts. The antioxidant activity of Centella (84%) was compared to grape seed extract (83%) and Vitamin C (88%). Its lipolytic activity was observed by the release of glycerol (115.9 μmol/L) at 0.02% concentration. Centella extracts exhibited similar UV protection effect to OMC at 10% concentration. In view of these results, the potential application of Centella in food and pharmaceutical industries is now widely open.     

Determination of chlorpyrifos and acephate in tropical soils and application in dissipation studies

A rapid and accurate method for the extraction and determination of the two organophosphorus insecticides, chlorpyrifos and acephate in top- and subsoil materials of three tropical clayey soils from Sarawak has been developed. Soil samples were extracted with ethyl acetate and the pesticides were determined by GC-FPD. High recoveries of 76–102% and 76–100% were obtained for acephate and chlorpyrifos respectively, at fortification levels of 0.01, 0.1 and 1 mg kg^?1 with standard deviations below 9.0%. The addition of water prior to the extraction was important for obtaining high and reproducible recoveries. The method did not require clean-up of the extracts prior to GC analysis and could be detected down to 0.01 mg kg^?1. A field study was conducted using the modified method to measure the degradation kinetics and migration of acephate and chlorpyrifos in one of the soils over a period of 84 days. The degradation of acephate and chlorpyrifos were rapid with half-lives of 3.3 and 8.7 days, respectively. Both pesticides were detected in subsoils 2 h after application at the deepest (50 cm) soil layers examined and at concentrations up to 5.42 mg kg^?1. Subsoil concentrations of acephate were higher than for chlorpyrifos, and subsoil concentrations of acephate peaked after it had started to degrade in the top soil. The subsoil concentrations of the pesticides were attributed to transport with soil particles (chlorpyrifos) and via solution (acephate) through pores and cracks present in the soil profiles. The study demonstrates the high mobility of even strongly retained and fast degrading pesticides under tropical humid conditions.     

Adsorption of Copper (II) onto Different Adsorbents

Removal of copper (II) from aqueous solution of CuCl₂·2H₂O by different adsorbents, namely, sissoo sawdust, activated carbon, and fly ash were investigated. Adsorption of copper (II) on sissoo sawdust, activated carbon, and fly ash has been studied using batch techniques. Kinetic and isotherm studies were determined as a function of the solution pH, temperature, contact time, adsorbent dosage, and initial adsorbate concentration. Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin isotherms were used to analyze the equilibrium data at different temperatures. The maximum adsorption capacities for copper (II) on sissoo sawdust, activated carbon, and fly ash adsorbents at 30, 40, and 50°C temperatures were found to be 263.2, 166.6, and 142.8; 125.0, 88.49, and 72.46; 69.93, 181.8, and 111.1 mg/g, respectively. The thermodynamics of copper (II) adsorption on sissoo sawdust, activated carbon, and fly ash indicates its spontaneous and endothermic nature. Kinetic studies showed that the adsorption followed a pseudo-second-order kinetic model.     

Deacetylation of Thioacetate using Acetyl Chloride in Methanol

A highly efficient method for the deacetylation of thioacetate is reported under mild acidic conditions employing acetyl chloride in methanol. Some of the major advantages are mild conditions, high efficiency, high yields, and easy operations.