Kum Sang Low

Crude palm oil characteristics and chlorophyll content.

The chlorophyll (CHL) content in palm oil extracted from oil palm fruits, Elaeis guineensis, at various stages of ripeness was determined. It was found that oils from ripe fruits of the same age contained different levels of CHL. In addition it was noted that fruits from palms planted at the centre and those at the edge of the field seemed to ripen at different rates. Those at the centre of the field contained higher levels of CHL when compared with those of the same age produced at the edge of the field. This phenomenon could be due to topographical effects whereby the palms at the edge of the field were exposed to much more sunlight. This probably hastened the process of fruit ripening. A survey on CHL levels in commercial CPO samples supplied by mills showed the presence of CHL in all samples analysed. The range observed was between 250 and 1800 μg kg−1 with a mean value of 930±107 μg kg−1. This implied wide variations in the ripeness of palm fruits processed by the mills. ©1997 SCI

A compact low inductance pulse energy driver system for capillary discharge EUV laser development

Summary form only given. A requirement for the development of EUV (5–50 nm) laser applications is a pulse power driver system that can deliver high peak currents and fast rise-times in order to be able to pump these lasers effectively. We report here the initial results in the development of a high current driver that is efficient, compact and scalable for EUV lasers.

A compact low inductance pulse energy driver system for pulse power applications

In recent years, there have been various developments of high-current discharge drivers used in pulsed-power technologies including linear transformer drivers and impedance-matching transformers. As the discharge current scales up, it becomes crucial to optimize the input energy requirements. A new system was designed to provide a scalable low inductance current driver suitable for pulse-power applications including z-pinch, plasma-focus, and other direct current drive applications. This paper explores the development of a new current driver for a system with a z-pinch load using six modular units of low inductance integrated multiple-capacitor assemblies developed by Specscan Sdn. Bhd. Each of these modular units comprise four folded aluminum foil and dielectric film capacitors arranged in a two-stage LC-inversion circuit. Six of these modular multi-capacitor assemblies were connected to a pair of hexagon-shaped transmission plates of 1 meter in diameter with a z-pinch load located in the center to form a voltage-discharge loop for an estimated loop circuit inductance of 6.31 nH. Six individual spark-gap switches were connected to the voltage inversion loops of the multi-capacitor assemblies. Voltages of +6.75 kV and -6.75 kV were applied across the switches to charge the capacitors requiring 280 J of total input energy. The switches were then triggered simultaneously to generate a voltage-inversion that provides a near-quadruple increase in voltage across the transmission plates to form a pulse-energy driver system. A peak voltage of approximately 24.4 kV was obtained at the z-pinch load with a peak current of 211 kA and a quarter-wave 10-90% rise time of 110 ns. The system generated 4.6 GW of peak power with a corresponding efficacy of 16.5 MW/J. This development illustrates a concept of an efficient scalable direct high current driver system for various pulse power applications using relatively low voltages. One particular interest in the future is the possibility of scaling these drivers to operate in the megaamperes range. This can be achieved if: a) the charging voltages are increased; and b) if the transmission plates are enlarged to accommodate a greater number of modular multi-capacitor units. This paper will describe how the existing z-pinch system operates and the results obtained. Projections will then be made on its potential current scaling while maintaining its input energy efficiencies.

Bis(N,N-dimethylthiocarbamoylthio)acetic acid.

Bis(N,N-dimethylthiocarbamoylthio)acetic acid, [(CH(3))(2)NC(=S)S](2)CHC(=O)OH or C(8)H(14)N(2)O(2)S(4), exists as a centrosymmetric hydrogen-bonded dimer [O.O 2.661 (3) A].