Kinetics and mechanism of free radical grafting of methyl acrylate onto sago starch

The graft copolymerization was carried out by methyl acrylate with sago starch in which ceric ammonium nitrate was used as an initiator. It has been found that the rates of graft polymerization and grafting efficiency were dependent upon the concentration of ceric ammonium nitrate (CAN), methyl acrylate (MA), sago starch (AGU, anhydro glucose unit), mineral acid (H₂SO₄), and as well as reaction temperature and period. A rate equation of polymerization was established from the proposed reaction mechanism, and the rate of polymerization (R_p) was the first‐order dependence of the MA monomer concentration and square root of the CAN concentration. A new kinetic model of the grafting reaction has been proposed, and a normal kinetics of methyl acrylate polymerization was observed. An equation of a predicted model relating the graft fraction of poly(methyl acrylate) with the sago starch has been derived, and validity of the predicted model was verified by the experimental results. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 784–791, 2000     

A least squares algorithm for a mixture model for compositional data

The estimation of a model for compositional data is studied where the data are approximated by a mixture of latent compositions. This model is variously known as “endmember analysis” or “latent budget analysis”. Two estimation procedures are available. The first uses a procedure which is incorrect in the sense that, although it claims to be a least squares procedure, it does not always minimize a least squares criterion. The second uses a maximum likelihood procedure starting from assumptions that are often violated for compositional data. In this paper we propose a constrained (weighted) least squares procedure for the estimation of the model.     

Preparing Malaysian vocational and technology teachers to integrate computer technology in teaching vocational and technology subjects

A study was conducted in three selected states in Malaysia to determine the preparedness of vocational and technology teachers to integrate computer technology in their classrooms. The study showed that teachers did not have a high level of general knowledge about computers (mean=6.3, sd.=2.97). They were not very knowledgeable in some computer software. They thought that they were not skillful in using computer software such as electronic spreadsheet (57.1%), word-processing and desktop publishing (50.8%), and database management (67.9%). Almost two-thirds of the respondents cannot do programming. Realizing that they did not have the necessary knowledge and skills, the majority of the teachers would like to attend training in using computers for instruction.     

Simple dispersion of graphene incorporated rubber composite for resistive pressure sensor application

We developed a resistive pressure sensor based on stand-alone film graphene incorporated natural rubber latex (NR/G) composite fabricated in a simple solution casting method. The graphene dispersion had multilayer properties and an average lateral size of ~60 nm successfully incorporated into the NR matrix to form bilayer graphene composite with the I_2D/I_G calculated ratio of 1.301. The pressure sensor shows high sensitivity (~ 0.2 kPa⁻¹), high cycle stability, and selective response to the applied pressure with a linear relationship of ~6.0 kPa. This work shows that graphene incorporated natural rubber latex pressure sensors with applicable potentials for smart wearable devices to allow pressure detection.     

Production and utilization of palm fatty acid distillate (PFAD)

PFAD (palm fatty acid distillate) is a by‐product of physical refining of crude palm oil products and is composed of free fatty acids (81.7%), glycerides (14.4%), squalene (0.8%), vitamin E (0.5%), sterols (0.4%) and other substances (2.2%). PFAD is used in the animal feed and laundry soap industries as well as a raw material for the oleochemicals industry. Vitamin E, squalene and phytosterols are value‐added products which could be extracted from PFAD and are of potential value for the nutraceutical and cosmetic industries.     

Enzymatic synthesis of palm olein-based fatty thiohydroxamic acids

Fatty thiohydroxamic acids (FTAs) have been successfully synthesized from palm olein and thiohydroxamic acid by a one-step lipase catalyzed reaction. The use of immobilized lipase (Lipozyme RMIM) as the catalyst for the preparation reaction provides an easy isolation of the enzyme from the products and other components in the reaction mixture. The FTAs were characterized using Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance ((1)H NMR) technique and elemental analysis. The highest conversion percentage (95 %) was obtained when the process was carried out for 30 hours using urea to palm oil ratio of 6.0: 1.0 at 40 °C. The method employed offers several advantages such as renewable and abundant of the raw material, simple reaction procedure, environmentally friendly process and high yield of the product.     

Variability, regularity, and complexity of time series generated by schizophrenic patients and control subjects

We analyzed time series generated by 20 schizophrenic patients and 20 sex- and age-matched control subjects using three nonlinear methods of time series analysis as test statistics: central tendency measure (CTM) from the scatter plots of first differences of data, approximate entropy (ApEn), and Lempel-Ziv (LZ) complexity. We divided our data into a training set (10 patients and 10 control subjects) and a test set (10 patients and 10 control subjects). The training set was used for algorithm development and optimum threshold selection. Each method was assessed prospectively using the test dataset. We obtained 80% sensitivity and 90% specificity with LZ complexity, 90% sensitivity, and 60% specificity with ApEn, and 70% sensitivity and 70% specificity with CTM. Our results indicate that there exist differences in the ability to generate random time series between schizophrenic subjects and controls, as estimated by the CTM, ApEn, and LZ. This finding agrees with most previous results showing that schizophrenic patients are characterized by less complex neurobehavioral and neuropsychologic measurements.     

Selective extraction,separation and recovery of Cu(II) in presence of Zn(II) and Ni(II) from leach liquor of waste printed circuit board using microcapsules coated with Cyanex 272

The study was conducted to optimize the selective extraction and recovery of Cu(II) in the presence of Zn(II) and Ni(II) from the leach liquor of waste printed circuit boards (PCBs). The extraction experiments were carried out according to 2⁴ factorial design of experiment to optimize the extraction factors. The design was analyzed using MINITAB to determine the main effects and interactions of the chosen extraction factors. The factors chosen were: extraction pH, amount of Cyanex 272 in dispersed phase during MC-Xs preparation, amount of MC-Xs and temperature. The pH, amount of MC-Xs and temperature were found to be statistically significant. The optimized experimental conditions for the Cu(II) extraction in presence of Zn(II) and Ni(II) were extraction pH 6.0, amount of Cyanex 272 in dispersed phase 3 g, amount of MC-Xs 2.5 g and Temperature 45 °C. Factorial design of experiment was also carried out to determine the Cu(II) stripping factors from the loaded MC-Xs using H₂SO₄ solution. The liquid-liquid extraction Cu(II) was conducted with the prime aim to evaluate the nature of Cu(II) complex extracted by Cyanex 272. Results showed that the extraction species is [Cu(HA₂)(Ac)·2HA]. Finally, a complete process for the separation and recovery of Cu(II), Zn(II) and Ni(II) from the leach liquor of waste PCBs was conducted based on the optimized experimental condition and effect of pH on extraction.     

Mitigating the anthropogenic global warming in the electric power industry

One of the most current and widely discussed factors that could lead to the ultimate end of man's existence and the world at large is global warming. Global warming, described as the greatest environmental challenge in the 21st century, is the increase in the average global air temperature near the surface of the Earth, caused by the gases that trap heat in the atmosphere called greenhouse gases (GHGs). These gases are emitted to the atmosphere mostly as a result of human activities, and can lead to global climate change. The economic losses arising from climate change presently valued at $125 billion annually, has been projected to increase to $600 billion per year by 2030, unless critical measures are taken to reduce the spate of GHG emissions. Globally, the power generation sector is responsible for the largest share of GHG emissions today. The reason for this is that most power plants worldwide still feed on fossil fuels, mostly coal and consequently produce the largest amount of CO₂ emitted into the atmosphere. Mitigating CO₂ emissions in the power industry therefore, would significantly contribute to the global efforts to control GHGs. This paper gives a brief overview of GHGs, discusses the factors that aid global warming, and examines the expected devastating effects of this fundamental global threat on the entire planet. The study further identifies the key areas to mitigate global warming with a particular focus on the electric power industry.