Device simulation of submicrometer gate p+-i-p+ diamond transistors

Two-dimensional device simulation of submicrometer gate diamond p ⁺-i-p⁺ transistors with a SiO₂ gate insulator was investigated using the MEDICI device simulation program. A large modulation of the source-to-drain current was obtained in the accumulation mode. The computed diamond device characteristics were equivalent or better than the simulation results of 6H-SiC MESFET's. It was concluded that the problems in diamond MESFET associated with the deep acceptor levels due to boron doping can be overcome in the p⁺ -i-p⁺ diamond FET's because of the hole injection and the space charge limited current     

A simple method for recovering the motile spermatozoa from extremely low quality sperm samples

Recovery of motile spermatozoa from extremely low quality samples for use in the intracytoplasmic sperm injection (ICSI) procedure is difficult. To solve this problem we developed a simple method to recover the motile spermatozoa using a 3% polyvinylpyrrolidone (PVP) droplet. After depositing a sperm pellet into this slightly viscous droplet, motile spermatozoa readily swam out to the clear area while immotile spermatozoa dispersed to a lesser extent, so that motile and immotile cells became clearly separated from each other. A total of 36 ICSI cycles using spermatozoa with extremely low quality characteristics were performed. We recovered the motile spermatozoa from all sperm samples from two sources of poor quality spermatozoa. Thirty-one cycles of ICSI with ejaculate resulted in fertilization and pregnancy rates of 54 and 29% respectively. Five cycles of ICSI with frozen-thawed epididymal spermatozoa resulted in fertilization and pregnancy rates of 70 and 60% respectively. The 3% PVP droplet method is very simple and easy to perform, so it may be useful for recovering the motile spermatozoa from extremely low quality sperm samples used for ICSI.     

Fibrolamellar carcinoma of the liver with a mixture of ordinary hepatocellular carcinoma: a case report

Fibrolamellar carcinoma (FLC) of the liver is a rare variant of hepatocellular carcinoma (HCC), and only 13 cases have been reported in Japan up to 1997. We described a histologically unusual case of FLC. A 52-yr-old man was admitted to our hospital for work-up of hepatic mass. Laboratory examinations revealed no abnormalities except elevated serum alpha-fetoprotein (AFP) (2098 ng/ml). A diagnosis of HCC was made by imaging findings, and left lobectomy of the liver was performed. Histologically, the tumor was composed of areas of FLC mixed with ordinary HCC and those of pure ordinary HCC. Staining for AFP was positive in the HCC component and negative in the FLC component. Some cases of such mixed tumors have been reported in Europe and the United States, but not in Japan. We regarded our case as the first of the mixed tumor in Japan.     

Low resistivity transparent conducting Al-doped ZnO films prepared by pulsed laser deposition

A series of AZO films were grown on glass substrates by a method of pulsed laser deposition using a split target divided into AZO (Al₂O₃: 1 wt.%) and AZO (Al₂O₃: 2 wt.%). The film deposition took place at a substrate temperature of 230 °C within a magnetic field applied perpendicularly to the plume. To suppress the droplet generation caused by the intense laser energy, the laser energy density was reduced to 0.75 J/cm² (15 mJ). For an approximately 280-nm thick-AZO film grown at a target-to-substrate distance of 25 mm, we obtained the lowest resistivity of 8.54×10⁻⁵ Ω·cm and an average transmittance of more than 88% in the visible range. In the cross-sectional TEM observation and XRD spectra, the regularity in the crystal growth was generated immediately from the interface between the substrate and the film.     

Isolation and characterization of 6-hydroxymethylpterin as the Crithidia growth-promoting factor from spinach chloroplasts

2-Amino-4-hydroxypteridine compounds were isolated as the Crithidia factor from spinach chloroplasts by DEAE-Sephadex A-50, DEAE-cellulose, Sephadex G-25, and thin-layer chromatography. One of the compounds was characterized as 6-hydroxymethylpterin by gas-liquid chromatography-mass spectrometry and by comparison with authentic specimen.     

Studies on chitin. VI. Binding of metal cations

The adsorption abilities of chitin and its congeners with two series of degrees of deacetylation prepared by two different deacetylation procedures were compared. Among the polysaccharides obtained by the heterogeneous method, those with higher amino group content had higher adsorption ability. Plots of collection percentages versus amino group content, however, did not give straight lines. The plot for the chelation on the congeners that were prepared by homogeneous hydrolysis had a maximum at about 50% amino group content, and the value was higher than that for the sample with the highest amino group content, which was prepared by heterogeneous hydrolysis. These results suggest that the polysaccharides with about 50% amino group content obtained by the homogeneous procedure are potentially useful for the removal of metals.     

EFFECT OF BAFFLE ON TRAY UNDER OSCILLATING CONDITION

Effect of baffle on a tray under oscillating conditions has been examined experimentally. To reduce the degree of liquid mixing and liquid channeling under oscillating conditions, it is necessary to install the baffles on tray.

Experiments were conducted with the air-water system, ft was found that the pressure drop change can be expressed as a sinusoidal function and the period coincides with tray oscillation. The degree of liquid mixing decreases when the baffles are installed on tray and it also decreases with the increase of liquid flow rate. The pressure drop increases with the installation of baffle on tray.

The suitable baffle number on tray is from 4 to 8 and in this region, the degree of liquid mixing reaches minimum and the liquid holdup takes a maximum value. @KEYWORDS: Tray, Oscillating, Liquid mixing, Baffle, Pressure drop, Liquid holdup.     

Emissivity of chlorinated polyethylene

The emissivity of chlorinated polyethylene containing varying amounts of combined chlorine has been investigated. It was found that the emissivity of these compounds increases significantly with increase in chlorination.     

Aging and thermal stability of Mg/SiC and Mg/Y2O3 reflection multilayers in the 25-35 nm region

Reflection measurements in the 25-35 nm region were made for Mg/SiC and Mg/Y2O3 multilayers kept in a low-humidity atmosphere for 4 or 5 years. Aged Mg/SiC multilayers keep their reflectances, and the reflectance value at 31.2 nm is 0.44 at 10 degrees of the normal angle of incidence. Aged Mg/Y2O3 multilayers change reflectance as top layer materials, and the best value at 30.1 nm is 0.40 at 10 degrees. Reflection measurements are also made for Mg-based multilayers that are annealed from room temperature to 400 degrees C at 50 degrees C intervals. Both multilayers keep their reflectance at annealing temperatures of 200 degrees C. These results suggest that both Mg-based multilayers can be applied to practical optics.     

Effect of Oxygen on the Self-formation of Carbonaceous Tribo-layer with Carbon Nitride Coatings under a Nitrogen Atmosphere

The ball-on-disk friction and wear tests of CN _X coatings (CN _X /CN _X ) were conducted under a nitrogen atmosphere with controlled relative humidity (RH) (3.4–40.0%RH) and oxygen concentration (100–21 × 10⁴ ppm) in this study. We found that the specific wear rate of CN _X coating on ball (W _b), which could give stable and low friction coefficient (<0.05), was below 3.0 × 10^?8 mm³/Nm. Average friction coefficients (µ _a) and W _b of CN _X /CN _X increased (µ _a: 0.02–0.33, W _b: 1.6 × 10^?8–2.4 × 10^?7 mm³/Nm) with increasing oxygen concentration (230–211,000 ppm) as well as RH (4.7–21.1%RH) under a nitrogen atmosphere. However, the W _b remained low value below 2.3 × 10^?8 mm³/Nm regardless of oxygen concentration (100–207,000 ppm) of a nitrogen atmosphere (3.4–3.9%RH) when CN _X -coated balls were slid against a hydrogenated CN _X (CN _X :H) coatings (CN _X /CN _X :H). Besides, the CN _X /CN _X :H achieved low and stable friction coefficient below 0.05 under a nitrogen atmosphere (10,000 ppmO₂) regardless of increasing RH up to 20%RH. Raman analysis indicated that the structure of carbon on the top surface of CN _X coating was changed from as-deposited CN _X coating in the case of low friction coefficient (<0.05). Furthermore, TOF-SIMS analysis provided the evidence that the carbon derived from CN _X -coated disk was considered to diffuse into the ball surface, and it mixed with the carbon derived from CN _X -coated ball on the wear scar, which formed the chemically bonded carbon tribo-layer. Low friction coefficient (<0.05) with CN _X coatings under a nitrogen atmosphere was achieved due to self-formation of the carbon tribo-layer.