Sterilization efficacy of a coaxial microwave plasma flow at atmospheric pressure

A coaxial cable for microwave transmission type of atmospheric low-temperature plasma source was developed. The plasma source has the advantages of portability, simple configuration, and ability to operate with a wide range of gases and mixtures of such gases. It mainly consists of a cavity, a quartz discharge tube, a coaxial cable, a microwave power source, and a gas supply system. Using this plasma source, the authors tried to clarify its sterilization efficacy against Geobacillus stearothermophilus. A log reduction number of G. stearothermophilus of at least 5 (10/sup -5/) was obtained under the following operating conditions: gas flow rate of argon of 14 SL/min, input power is 400 W, and substrate surface temperature of 353 K. Distributions of temperature and velocities of gas were also measured two-dimensionally by using an E-type thermocouple and a Pitot tube, respectively. The temperature distributions and the peak value of temperature were found to be influenced by the gas flow rate and the kinds of gas mixtures.     

Generation and measurement of subpicosecond electron beam pulses

The generation and measurement of subpicosecond electron beam pulses by the transverse-longitudinal combination gate system is described. The temporal property of the pulse gate is analyzed with the help of the longitudinal emittance diagram. Close agreement has been obtained between the calculated pulse width and the observed one which was measured by the Lissajous's figure method. A beam pulse of 0.2 ps (FWHM) was produced.     

Luminescent passive-oxidized silicon quantum dots as biological staining labels and their cytotoxicity effects at high concentration

Semiconductor quantum dots (QDs) hold some advantages over conventional organic fluorescent dyes. Due to these advantages, they are becoming increasingly popular in the field of bioimaging. However, recent work suggests that cadmium based QDs affect cellular activity. As a substitute for cadmium based QDs, we have developed photoluminescent stable silicon quantum dots (Si-QDs) with a passive-oxidation technique. Si-QDs (size: 6.5 ± 1.5?nm) emit green light, and they have been used as biological labels for living cell imaging. In order to determine the minimum concentration for cytotoxicity, we investigated the response of HeLa cells. We have shown that the toxicity of Si-QDs was not observed at 112?μg?ml(-1) and that Si-QDs were less toxic than CdSe-QDs at high concentration in mitochondrial assays and with lactate dehydrogenase (LDH) assays. Especially under UV exposure, Si-QDs were more than ten times safer than CdSe-QDs. We suggest that one mechanism for the cytotoxicity is that Si-QDs can generate oxygen radicals and these radicals are associated with membrane damages. This work has demonstrated the suitability of Si-QDs for bioimaging in lower concentration, and their cytotoxicity and one toxicity mechanism at high concentration.     

Synthesis and biological activities of optically active 6-[3-(3,4-dimethoxybenzylamino)-2-hydroxypropoxy]-2(1H)-quinolinone (OPC-18790)

The enantiomers of 6-[3-(3,4-dimethoxybenzylamino)-2-hydroxypropoxy]-2(1H)-quinolinon e (OPC-18790), a novel cardiotonic agent, were synthesized and evaluated for positive inotropic activity. The key intermediates, 2,3-epoxypropoxy derivatives, were obtained by the alkylation of 6-hydroxy-2(1H)-quinolinone with optically active epichlorohydrin and subsequent ring closure. In an in vitro study, the (R)-(+)-isomer was about 10-fold more potent than the (S)-(-)-isomer.     

Membrane fusion events during endocytosis in mouse kidney tubule cells detected by rapid freezing followed by freeze-substitution

Membrane fusion events during endocytosis were examined in renal proximal tubule cells processed by rapid freezing followed by freeze-substitution. An extensive fusion site of the membranes between two apical vacuoles or a vacuole and a lysosome, which appeared as a pentalaminar structure, was not observed in this study, though such a pentalaminar structure has been found in chemically fixed specimens. In vitro experiments using subcellular fractions revealed that the pentalaminar structure did not always represent the initial stage of membrane fusion. Membrane fusion appeared to occur in a specific membrane site, wHere a minute pore connecting the two lumens was formed immediately after the two membranes came into contact with each other. Some pore necks showed an asymmetrical feature which consisted of a sharp corner and a gently curved corner. Enlargement of the pore appears to be mediated by a fibrous structure observed near the sharp corner of the pore neck.     

High-power CO laser transmission through As-S glass fibres

In the letter we experimentally demonstrate high-power CO laser transmission through As-S glass fibres. The maximum transmitted laser power reaches about 40 W with a 420 cm-long 1000 ?m-diameter fibre. In this case no damage is observed in the fibre. Calculating from the damage threshold power intensity of 10.0 kW/cm2, it appears possible to transmit a power of up to about 80 W with a 1000 ?m-diameter fibre.     

Development of nickel/metal-hydride batteries for EVs and HEVs

This paper is to introduce the nickel/metal-hydride (Ni/MH) batteries for electric vehicles (EVs) and hybrid electric vehicles (HEVs) developed and mass-produced by our company. EV-95 for EVs enables a vehicle to drive approximately 200 km per charge. As the specific power is extremely high, more than 200 W/kg at 80% depth of discharge (DOD), the acceleration performance is equivalent to that of gasoline fuel automobiles. The life characteristic is also superior. This battery gives the satisfactory result of more than 1000 cycles in bench tests and approximately 4-year on-board driving. EV-28 developed for small EVs comprises of a compact and light battery module with high specific power of 300 W/kg at 80% DOD by introducing a new technology for internal cell connection. Meanwhile, our cylindrical battery for the HEV was adopted into the first generation Toyota Prius in 1997 which is the world’s first mass-product HEV, and has a high specific power of 600 W/kg. Its life characteristic was found to be equivalent to more than 100,000 km driving. Furthermore, a new prismatic module in which six cells are connected internally was used for the second generation Prius in 2000. The prismatic battery comprises of a compact and light battery pack with a high specific power of 1000 W/kg, which is approximately 1.7 times that of conventional cylindrical batteries, as a consequence of the development of a new internal cell connection and a new current collection structure.