Optimal temperature policies for batchwise thermally‐initiated bulk polymerization of styrene

Abstract

For batchwise thermally‐initiated bulk polymerization of styrene, the maximum principle is applied to search for an optimal temperature policy, by which the reaction time is minimal, for the system having predetermined average molecular weight and monomer conversion at end time and upper temperature limit. A set of simple equations for calculating the optimal temperature policy is obtained. Some numerical calculations are also presented.     

Tribological Behavior of an Aluminum Matrix Composite with Al4SiC4 Reinforcement under Dry Sliding Condition

In the present research work, an aluminum-based metal matrix composite with in situ Al₄SiC₄ particles has been developed by the incorporation of TiC particles in commercial aluminum melt through a stir-casting method. Microstructure evaluation in correlation to developed hardness and mechanical properties was performed. Furthermore, the dry sliding wear behavior of commercial aluminum and commercial aluminum–5 vol% Al₄SiC₄ composite was investigated at low sliding speed (1 ms^?1) against a hardened EN 31 disk at different loads. The wear mechanism involved adhesion and microcutting–abrasion at lower loads. On the other hand, at higher loads, abrasive wear involving microcutting along with adherent oxide formation was observed. The overall wear rate increased with load in the alloy as well as in the composite. Moreover, the overall wear rate of the composite was lower than that of the commercial aluminum at all applied loads.` The severe wear region at 39.2 N load in the case of the commercial aluminum–5 vol% Al₄SiC₄ composite was found to be delayed up to a longer sliding distance compared to commercial aluminum. The in situ Al₄SiC₄ particles offered resistance to adhesive wear. Accordingly, the commercial aluminum–5 vol% Al₄SiC₄ composite exhibited superior wear resistance compared to the commercial aluminum.     

Recovery of residual oil from the centrifuge sludge of a palm oil mill: Effect of enzyme digestion and surfactant treatment

Residual oil recovery from the centrifuge sludge of a palm oil mill was investigated by treating with enzyme (Celluclast) followed by washing the digested substrate with surfactant. The optimal conditions for enzyme digestion with respect to pH, temperature, reaction time, concentrations of enzyme and surfactant were evaluated. The possible role of the surfactant in the oil recovery process is discussed. The chemical composition and physical properties of the sludge before and after treatment were determined and its significance in the subsequent effluent treatment/utilization of the sludge is discussed. Part of this work was presented at the American Chemical Society’s 63rd Colloid and Surface Science Symposium, Seattle, Washington, June 18–20, 1989.     

On temperature‐dependence of RC networks

Abstract

Resistor‐Capacitor, abbreviated as RC, networks are widely used in discrete as well as integrated circuits. Both resistors and capacitors are functions of temperature, especially, the capacitors. For many applications, it is desired to temperature‐compensate the RC networks. In this paper, a technique is introduced to temperature‐compensate RC networks that are composed of mutually independent parts. An experiment is performed to check validity of the theory. And the experimental results agree well with the theory.     

Carbon credit and emission trading: Anaerobic wastewater treatment

The concept of carbon credit arose out of increasing awareness of the need to reduce emissions of greenhouse gases to combat global warming which was formalized in the Kyoto Protocol. In addition to contribution to sustainable development with energy recovery in the form of methane, carbon credits can be claimed by application of advanced anaerobic processes in wastewater treatment for reducing emissions of greenhouse gases. As anaerobic granular systems are capable of handling high organic loadings concomitant with high strength wastewater and short hydraulic retention time, they could render much more carbon credits than other conventional anaerobic systems. Granular anaerobic processes have become an attractive choice of treatment technology especially for high strength wastewaters, considering the fact that in addition to efficient waste degradation, the carbon credits can be used to generate revenue and to finance the project. This paper presents a scenario on emission reduction based on a methane recovery and utilisation project. An example analysis on emission reduction and the future trend is also outlined.     

Development and application of less‐mercury flat fluorescent lamps for backlights and general lighting

Abstract— A novel flat discharge fluorescent lamp used as the light source of backlight modules for LCDs and general lighting systems has been researched and developed. This new type of lamp is a less‐mercury flat fluorescent lamp with two‐dimensional emission and superior to conventional one‐dimensional cold‐cathode fluorescent lamps in terms of optics, energy‐savings, production efficiency, reliability, and chromatic performances. Physical characterization of the optics, temperature, mechanical design, thermal shocking, reliability, and corresponding environments have verified that flat fluorescent lamps will be the next‐generation light sources for backlight modules and general lighting systems.     

LaNiO3/g-C3N4 nanocomposite: An efficient Z-scheme photocatalyst for wastewater treatment using direct sunlight

The major findings in this report are (i) development of nanocomposite photocatalyst working through Z-scheme charge transfer pathway across the heterojunction, (ii) utilization of direct sunlight as the photo-source, and (iii) prospect of ligand-hole in photocatalysis through enhanced sub-band gap absorption. The photocatalysts, namely LaNiO₃, g-C₃N₄ and LaNiO₃/g-C₃N₄ nanocomposites were synthesized via facile route and were characterized for their structure, morphology, microstructure, texture, elemental mapping and surface oxidation states by using several physicochemical techniques. The photocatalytic performance of the nanocomposite was tested through the degradation of hazardous azo dye pollutants, namely reactive black 5 and methylene blue as well as the colorless antibiotic-pollutant tetracycline hydrochloride in aqueous solution in presence of natural sunlight with excellent recycling activity. The 10%LaNiO₃/g-C₃N₄ nanocomposite sample shows the best catalytic activity, degrading respectively 94%, 98.6% and 88.1% of reactive black 5, methylene blue and tetracycline hydrochloride in 60, 180 and 120 min. The photocatalytic activity of the nanocomposite phase is several times superior to that of the pure phases. The improvements of photocatalytic activity of g-C₃N₄ in the nanocomposite have been rationalized through the construction of direct Z-scheme heterojunction and suppression of electron–hole pair recombination efficiency. The enhanced photo-absorption of the nanocomposite can possibly be related to sub-bandgap absorption, which is associated to the midgap state originating from ligand-hole formation or defects in the structure. The photodegradation process is mediated through the formation of super oxide radical (^˙O₂^¯) and hole (h⁺) as the main responsible species.