Progress in space charge measurement of solid insulating materialsin Japan

The space charge measurement technique may be applied to diagnostic technology for high-voltage machines in the near future. The authors review the progress in the various methods of space charge measurement in Japan     

Measurement of slowly varying component in phase error distribution of a large-channel-spacing arrayed-waveguide grating

It has been difficult to measure the phase error distribution of a large-channel-spacing arrayed-waveguide grating (AWG) with optical low coherence interferometry (OLCI). In this reported work OLCI was successfully used to measure the slowly varying component in the distribution of a 1 THz-spaced AWG that was the primary filter in an ultra-high-density multi/demultiplexer. The spectral sidelobe of the AWG can be reduced by using the component to achieve the lowest possible accumulated crosstalk in the multi/demultiplexer.     

Corrosion behavior of Ti-Ag alloys used in dentistry in lactic acid solution

The purpose of this study was to evaluate the corrosion resistance of experimental Ti-Ag alloys used as dental materials. An elution test and a rest-potential measurement of alloys with 5–30 mass.% Ag were performed in a 1 % lactic acid solution. The amount of Ti ions released from the α phase of the Ti-Ag alloys decreased as the Ag concentration increased. TiAg present in the alloys dissolved preferentially, but Ti₂Ag did not. The rest potentials of the Ti-Ag alloys were significantly higher than that of pure titanium. The elution test and the rest-potential measurement revealed that the Ti-Ag alloys, which formed a single α-titanium structure or contained a titanium and Ti₂Ag, had excellent corrosion resistance that was comparable or superior to that of pure titanium.     

Performance of passive heat removal by an air‐cooling panel from a high‐temperature gas‐cooled reactor

An experiment was performed to simulate an air‐cooling panel system for passive decay heat removal from a high‐temperature gas‐cooled reactor to investigate the performance of decay heat removal and the temperature distributions of components of the system. The experimental apparatus consisted of a pressure vessel 1 m wide and 3 m high. Nineteen simulated standpipes containing heaters with a maximum heating rate of 100 kW simulated residual heat of the core, and the cooling panels surrounded the pressure vessel. An analytical code (THANPACST2) was applied to the experimental data to investigate the validity of the analytical method and the model proposed. Under the conditions of helium gas at a pressure of 0.64 MPa and temperature of 514 °C in the pressure vessel, the predicted temperature distribution in the pressure vessel was estimated and was within ?10 to +50 °C as compared to the experimental data. The analysis indicated that the heat transferred to the cooling panel was 15.4% less than the experimental value. © 2002 Wiley Periodicals, Inc. Heat Trans Asian Res, 31(8): 665–677, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10061     

Antibiotic contamination and occurrence of antibiotic-resistant bacteria in aquatic environments of northern Vietnam

The ubiquitous application and release of antibiotics to the environment can result in bacterial antibiotic resistance, which in turn can be a serious risk to humans and other animals. Southeast Asian countries commonly apply an integrated recycling farm system called VAC (Vegetable, Aquaculture and Caged animal). In the VAC environment, antibiotics are released from animal and human origins, which would cause antibiotic-resistant bacteria (ARB). This study evaluated occurrence of ARB in the VAC environment in northern Vietnam, with quantitative analysis of antibiotic pollution. We found that sulfonamides were commonly detected at all sites. In dry season, while sulfamethazine was a major contaminant in pig farm pond (475-6662 ng/l) and less common in city canal and aquaculture sites, sulfamethoxazole was a major one in city canal (612-4330 ng/l). Erythromycin (154-2246 ng/l) and clarithromycin (2.8-778 ng/ml) were the common macrolides in city canal, but very low concentrations in pig farm pond and aquaculture sites. High frequencies of sulfamethoxazole-resistant bacteria (2.14-94.44%) were found whereas the occurrence rates of erythromycin-resistant bacteria were lower (< 0.01-38.8%). A positive correlation was found between sulfamethoxazole concentration and occurrence of sulfamethoxazole-resistant bacteria in dry season. The sulfamethoxazole-resistant isolates were found to belong to 25 genera. Acinetobacter and Aeromonas were the major genera. Twenty three of 25 genera contained sul genes. This study showed specific contamination patterns in city and VAC environments and concluded that ARB occurred not only within contaminated sites but also those less contaminated. Various species can obtain resistance in VAC environment, which would be reservoir of drug resistance genes. Occurrence of ARB is suggested to relate with rainfall condition and horizontal gene transfer in diverse microbial community.     

Production of D-lyxose from D-glucose by microbial and enzymatic reactions

D-arabitol was first prepared from D-glucose using Candida famata R28. The reaction gave 5.0% D-arabitol from 10.0% D-glucose. D-arabitol was then almost completely converted to D-xylulose using Acetobacter aceti IFO 3281. Finally, D-lyxose was prepared from D-xylulose enzymatically using L-ribose isomerase from toluene-treated cells of Acinetobacter sp. strain DL-28. The isomerization reaction progressed steadily and the concentration of D-xylulose increased from 1.0 to 10.0%. About 70% of D-xylulose was converted to D-lyxose in all cases. Separation of residual D-xylulose from the reaction mixture is very difficult to achieve by column chromatography, but D-xylulose could be selectively degraded easily using Saccharomyces cerevisiae IFO 0841. The product was crystallized and was confirmed to be D-lyxose by HPLC, 13C-NMR spectra, IR spectra analysis, and optical rotation measurement.     

VRLA Ultrabattery for high-rate partial-state-of-charge operation

The objective of this study is to produce and test the hybrid valve-regulated Ultrabattery designed specifically for hybrid-electric vehicle duty, i.e., high-rate partial-state-of-charge operation. The Ultrabattery developed by CSIRO Energy Technology is a hybrid energy-storage device, which combines an asymmetric supercapacitor, and a lead-acid battery in one unit cells, taking the best from both technologies without the need for extra, expensive electronic controls. The capacitor will enhance the power and lifespan of the lead-acid battery as it acts as a buffer during high-rate discharging and charging. Consequently, this hybrid technology is able to provide and absorb charge rapidly during vehicle acceleration and braking. The work programme of this study is divided into two main parts, namely, field trial of prototype Ultrabatteries in a Honda Insight HEV and laboratory tests of prototype batteries. In this paper, the performance of prototype Ultrabatteries under different laboratory tests is reported.