The aging of the anodic oxide of titanium during potentiostatic condition by ellipsometry

The aging effect of the anodic oxide film on titanium under constant potential oxidation was investigated by 3-parameter (3-P) ellipsometry in 0.1 mol dm⁻³ sulfuric acid solution. The oxide film was initially formed by a potential sweep oxidation, where the film with a low refractive index grew at relatively high rate. From the low value of the refractive index, the oxide film is assumed to be a hydrated structure. After the sweep oxidation to 4.26 V vs. reversible hydrogen electrode, the constant potential oxidation was performed at a potential of 4.26 V to examine the aging effect of the hydrated oxide film by 3-P ellipsometry. It was found that the refractive index of the oxide film increased from 2.39 to 2.59 during the aging of the constant potential oxidation, and the thickness decreased. The increase of the refractive index and the decrease of thickness may be explained by conversion from the hydrated oxide to a dehydrated oxide during the aging.     

A study of three‐dimensional observation of prebreakdown phenomena in dielectric liquids

This paper presents a new method which visualizes the high‐speed three‐dimensional images of prebreakdown streamers in dielectric liquids. A new optical system, having two crossed light axes to observe the needle tip from different directions, was designed. The shadowgraphic images from these two directions were combined through a beam splitter and focused on the photo‐cathode of an image converter camera. The photograph taken by this high‐speed shadowgraph system was reconstructed to three‐dimensional images using an image scanner and a computer. Using this system, the growth and decay processes of the streamer in cyclohexane were investigated. © 1999 Scripta Technica, Electr Eng Jpn, 128(4): 9–15, 1999     

Thermally stimulated current and thermally stimulated charge distribution in electron‐beam‐irradiated PMMA

The relationship between the external current J_ter(t), the conduction current J_c(x, t), and the displacement current ϵ∂E(x, T)/∂t of an electron‐beam‐irradiated PMMA is discussed in terms of measurements of the thermally stimulated current (TSC) and the thermally stimulated space charge distribution (TS‐SCD). ϵ∂E(x, T)/∂t is calculated from TS‐SCD measurements obtained with an improved pulsed electroacoustic (PEA) system. By virtue of the conservation of charge, J_c(x, t) is easily calculated from the measured J_ter(t) and the calculated ϵ∂E(x, T)/∂t. In this report, an approach to the conduction current analysis using the theory of conservation of charge is described and an analysis of the conduction current in an electron‐beam‐irradiated PMMA is introduced as a typical example. © 1999 Scripta Technica, Electr Eng Jpn, 128(2): 1–6, 1999     

Overexpression of the fanconi anemia group C gene (FAC) protects hematopoietic progenitors from death induced by Fas-mediated apoptosis

Fanconi anemia is a rare, inherited disorder characterized by bone marrow failure, congenital malformations, and cancer susceptibility. The group C Fanconi anemia gene, FAC, identified by expression cloning methods, encodes a protein of unknown function that may be involved in the response to apoptotic stimuli. Hematopoietic progenitor cells from Fac knock-out mice are hypersensitive to IFN-gamma, a molecule that can induce apoptosis through up-regulation of the Fas death receptor. In this study, we used FAC-overexpressing transgenic mice to examine the relationship between FAC and Fas-triggered cell death. Hematopoietic progenitors from FAC-transgenic mice were up to 10-fold less sensitive to the cytolytic effect of Fas-ligation. Our experiments implicate FAC in the regulation of apoptosis mediated by the Fas death receptor.     

Hyperspectral mapping-combining cathodoluminescence and X-ray collection in an electron microprobe

An optical spectrometer has been integrated into a JEOL 8900R electron microprobe, which allows simultaneous collection of light, X-ray, and electron signals. The cathodoluminescence signal is collected from a monocular eyepiece, which is integrated into the electron optics of the electron microprobe. The optical acquisition is synchronized with the stage motion. X-ray lines of major elements are collected using an energy dispersive spectrometer, X-ray lines of minor elements are collected using wavelength dispersive spectrometers, and the secondary and backscattered electron signals are collected using standard detectors. In mapping mode of operation the different signals are collected at each pixel with map sizes typically ranging from 1 million to 10 million pixels. This represents a significant amount of data from which the major correlations and associations in the map can be determined. Summing over a small number of channels and examining only a subset of the complete wavelength range are the strategies that have been developed to reduce the size of the data handled. The application of this mapping technique is demonstrated with two examples, zircons and refractory bricks. Zircons with various degrees of metamictization have been characterized, and inclusions differentiated using a combination of cathodoluminescence and X-ray maps. Examination of refractory bricks reveals subtle chemical changes in the spinel grains.     

Component spatial pattern analysis of chemicals by use of two-dimensional electro-optic terahertz imaging

We demonstrate a method of chemical mapping by using the transillumination terahertz (THz) images obtained by two-dimensional electro-optic THz imaging. The images and spectral data were measured between 0.1 and 1.0 THz. An experimental sample consisting of three chemicals was prepared, with one in two concentrations. By introducing the component spatial pattern analysis based on the least-squares method, the chemical composition, spatial distribution, and difference in concentration were clearly determined.     

Non-ignition of an ejected flame through a gap greater than the quenching distance

When a gap is greater than the quenching distance, the flame from an explosion inside a chamber can pass through the gap, but it will not always ignite an outside combustible mixture. There is a non-ignition gap distance, greater than the quenching distance, below which ignition will not occur, and above which it will. The present paper presents experimental determinations of non-ignition gap distances for different values of several parameters (gap width, number of gaps, and chamber volume) for various rectangular gaps with a wide range of lengths. A rectangular gap has three dimensions. One of these is here referred to as the gap distance, the others being gap width and gap length; diagramme definitions of the terms are given. The gap distance for non-ignition varies with the values chosen for the other two dimensions. It increases as the gap width decreases. But when gap length is varied for gap widths over 4.0 cm, the non-ignition gap distance first increases with increasing gap length, and then levels off. A second increase may occur or not, depending on other parameters. In particular, any given sectional gap area (fixed values for gap width and gap distance) may be subdivided, giving rise to multi-layered gaps. Experiment establishes that such subdivision is available as a method of preventing ignition of an outside combustible mixture, since ignition may occur through a single gap of given area and not through a subdivided multi-layered gap of the same area. At multi-layered gaps, one gap flame is far in advance of the others. Other gap flames are either soon extinguished within the gap, or advance a short distance without emerging. It seems permissible to consider the resultant as one flame for analysis. The magnitude of the non-ignition gap distance for multi-layered gaps is proportional to ut, u being the ejection velocity of the flame from the gap, and t the time taken for the flame to pass from the jet origin to the gap exit.     

Resistance to gentamicin and vancomycin in enterococcal strains isolated from retail broiler chickens in Japan

A total of 137 Enterococcus strains isolated from chicken meat were subjected to antimicrobial susceptibility tests. Strains with the vanCl gene were isolated from seven of nine samples of chicken meat processed in Japan and from all chickens from China and Brazil between July 2001 and April 2002. The pulsed-field gel electrophoresis (PFGE) patterns of the isolates were distinguishable from each other, suggesting that VanCl-type vancomycin-resistant Enterococcus is preferentially colonized in broiler chickens in these countries. The incidence of high-level gentamicin resistant (HLGR) enterococci that harbored the aac(6')-le-aph(2")-la or aph(2')-Id gene varied among the countries from which the chickens originated (Japan, 2 of 65; China, 11 of 43; Brazil, 6 of 29). Moreover, the PFGE patterns of the HLGR strains were distinguishable from each other, except for two strains obtained from chickens from Brazil. The results suggest that HLGR Enterococcus is highly prevalent in broiler chickens.     

Solar coal gasification

A preliminary evaluation of the technical and economic feasibility of solar coal gasification has been performed. The analysis indicates that the medium-Btu product gas from a solar coal-gasification plant would not only be less expensive than that from a Lurgi coal-gasification plant but also would need considerably less coal to produce the same amount of gas. A number of possible designs for solar coal-gasification reactors are presented. These designs allow solar energy to be chemically stored while at the same time coal is converted to a clean-burning medium-Btu gas.     

Inhibitory effects of Enterococcus strains obtained from a probiotic product on in vitro growth of Salmonella enterica serovar enteritidis strain IFO3313

Enterococcus faecium and Enterococcus gallinarum strains were isolated from a commercial probiotic product and the effects of these strains on the growth of Salmonella enterica serovar Enteritidis strain IFO3313 were investigated. Viable cell counts of Salmonella Enteritidis in mixed cultures with the probiotic product isolate of E. faecium were significantly (P < 0.05) lower than those in pure cultures after 6, 8, and 24 h when the cultures were incubated in heart infusion broth at 37 and 41 degrees C. Significant differences in viable cell counts of Salmonella Enteritidis in mixed cultures with the probiotic product isolate of E. gallinarum and those in pure cultures were also observed after 8 and 24 h at 37 and 41degrees C. Similar observations were shown in mixed cultures of Salmonella Enteritidis with the reference strains of E. faecium GIFU8355 and E. gallinarum ATCC 49573. Significant differences in viable cell counts of these enterococcal strains were not shown among pure and mixed cultures with Salmonella Enteritidis. The pH values in pure and mixed cultures were 7.0 or 7.5 throughout the experiments. E. faecium strains were found to harbor the genes encoding enterocins A and B and showed inhibitory zones with a diameter of 4 to 6 mm against growth of Salmonella Enteritidis in the enterocin production assays. However, the E. gallinarum strains possessed neither of the enterocin genes tested and exhibited no inhibition zone in the enterocin production assays. These results indicated that enterococcal strains exhibit inhibitory effects on the growth of Salmonella Enteritidis and these effects were due to both enterocin and nonenterocin factors.