Supercritical drying of SiO2-TiO2 sol-pillared clays

The interlayers of montmorillonite clay were pillared with silica-titania sol particles by ion exchange in aqueous solutions. The water in the pillared clay was substituted with ethanol which was in turn extracted with CO₂ under supercritical conditions. This drying procedure avoids the formation of liquid-vapour interfaces which give rise to shrinkage of the swelled pillared structure. Highly porous structures with well developed card-house structures resulted. The pore structure was investigated and compared with that of samples prepared by conventional air-drying procedures.     

SAW velocity measurement of crystals and thin films by the phasevelocity scanning of interference fringes

We present principle and application of a novel noncontact velocity measurement of surface acoustic waves (SAW) on crystals and thin films using laser interference fringes scanned at the phase velocity of SAW. The scanning interference fringes (SIF) are produced by intersecting two laser beams with a frequency difference. The SAW velocity within the laser beam spot is measured as the ratio of observed SAW frequency and predetermined wave number of the SIF. The frequency measurement can be quite precise because of a large number of generated SAW carriers and amplitude enhancement effect. The SAW velocity measurement is free from the water loading effect accompanying the leaky SAW measurements. This principle was successfully applied to evaluate Si ₃N₄ and SiO₂ films deposited on Si (001) surface     

Detection of proliferating cell nuclear antigen (PCNA) in peripheral blood mononuclear cells and sera of patients with malignant lymphoma

The proximity of farms to badger setts was compared between farms that had experienced a tuberculosis breakdown and those that had not, over the 6 year period from 1988 to 1993. The data were derived from a badger removal study conducted in East Offaly County in the Republic of Ireland. Badger removal began in 1989 and continued through 1993; by the end of 1990, approximately 80% of all badgers caught in the 6 year period had been removed. All badgers were examined, grossly, for evidence of tuberculosis. Tuberculosis status of the approximately 900 study herds was based on the results of the single intradermal comparative skin test and/or lesions of bovine tuberculosis. All herds were tested at least once annually. The number of herds experiencing bovine tuberculosis declined over the period, particularly in the years 1992 and 1993. The data on farm and badger sett location were stored and analysed, initially, in a geographical information system. Owing to the badger removal programme, the distance between the barn yard of a typical farm and the nearest occupied badger sett increased, by about 300 m year-1, and by about 600 m year-1 to the closest infected sett. In bivariate analyses, in the years 1988 and 1989, the risk of tuberculosis declined with increasing distance to a badger sett containing one or more tuberculous badgers. In multivariable logistic regression analyses, year and the average number of cattle tested per farm per year were controlled. A second identical analysis was conducted to control for the repeated observations on the same herds using generalised estimating equations. In both analyses, the risk of a multiple reactor tuberculosis breakdown decreased for herds at least 1000 m away from an infected badger sett, and increased as the number of infected badgers per infected sett increased. Despite the significantly reduced risk of a breakdown with increasing distance to infected badger setts, the relationship was not strong (sensitivity and specificity of the model in the low 70% range) and explained only 9-19% of tuberculosis breakdowns.     

Corneal epithelial basement membrane after experimental anterior stromal puncture in guinea pigs: immunohistochemical study

We investigated alterations in the immunolocalization of the components of epithelial basement membrane (BM), type IV collagen, and laminin in guinea pigs subjected to anterior stromal puncture (ASP) of the cornea performed with a standardized needle. Localization of BM components beneath the corneal epithelium was indicated by laminin immunoreactivity. The BM was interrupted by needle punctures immediately after ASP. During healing, type IV collagen immunoreactivity was detected transiently in the BM of some of the ASP-treated corneas, but no reactivity was observed in normal epithelial BM. Development of type IV collagen immunoreactivity was probably caused by an alteration of the alpha-chains or by an unmasking of the antigenicity of this collagen type, which may be related to an increase in the adhesiveness of the epithelium following ASP.     

A new system for the electrodeposition coatings based on TV-methacryloylcarbamate

N-Methacryloylcarbamate (N-MAC), which is an original monomer of Nippon Paint, is a heterofunctional monomer which has a polymerizable double bond and an acylcarbamate group in the same molecule. It has four characteristic properties, which have been developed for use in coatings. These are: a molecular weight that can be controlled easily by the amount of radical initiator used irrespective of the kind of acylcarbamate; the reactivity of the acylcarbamate group in the polymer is lower with an alcohol than in a monomer. However, the reactivity of the acylcarbamate group in the polymer with alcohol is much higher than that of carbamate group with alcohol; a curing temperature dependent on the kind of acylcarbamate group; and an acylcarbamate group that can react with a low nucleophilic active hydrogen such as that of a secondary alcohol. An electrodeposition paint has been developed from these properties since the activated acylcarbamate group in the N-MAC polymer makes it possible to design a low temperature crosslinking system, the flexibility in design of the main resin with respect to the active hydrogen makes it possible to improve the storage stability because of high reactivities of N-MAC polymer with active hydrogen compounds, and a core/shell structure makes it possible to make low temperature crosslinking compatible with good storage stability.     

Calculation of magnetic near field generated by the contact discharge of an ESD gun

An ESD (electrostatic discharge) testing is specified in the IEC 61000‐4‐2, in which the detailed waveform of the discharge current injected by an ESD gun is prescribed. However, due to lack of understanding of the discharge process, it is difficult to confirm whether or not the IEC current waveform can be injected onto actual equipment. We thus previously proposed an equivalent circuit model for the ESD gun based on its geometrical structure, and showed decisive factors for the discharge current. In this study, in order to confirm the feasibility of the above equivalent circuit model, we measured with a 6‐GHz wide‐band digital oscilloscope the discharge current through an SMA connector and the resultant magnetic near field for the contact discharge of an ESD gun. As a result, we found that both measured waveforms approximately agree with those calculated from our equivalent circuit model. We then measured with respect to charge voltages the magnetic near fields for the contact discharge of the ESD gun to the ground, which revealed that the measured waveform around the first peak is in fair agreement with the calculated one. Furthermore, we found that the magnetic field peak increases with increasing charge voltage, whose dependence can be predicted from our equivalent model. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(1): 17–24, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20194     

Thermoelectric Properties of Ca3Co4-x Ga x O9+δ Prepared by Thermal Hydro-decomposition

The polycrystalline samples of Ca₃Co_4-x Ga _x O_9+δ (0 ≤ x ≤ 0.15) were prepared by a simple thermal hydro-decomposition method. The high density ceramics were fabricated using a spark plasma sintering technique. The crystal structure of calcined powders was characterized by x-ray diffraction. The single phase of Ca₃Co_4-x Ga _x O_9+δ was obtained. The scanning electron micrograph illustrated the grain alignment perpendicular to the direction of the pressure in the sintering process. The evidence from x-ray absorption near edge spectra were used to confirm the oxidation state of the Ga dopant. The thermoelectric properties of the misfit-layered of Ca₃Co_4-x Ga _x O_9+δ were investigated. Seebeck coefficient tended to decrease with increasing Ga content due to the hole-doping effect. The electrical resistivity and thermal conductivity were monotonically decreased with increasing Ga content. The Ga doping of x = 0.15 showed the highest power factor of 3.99 × 10^-4 W/mK² at 1,023 K and the lowest thermal conductivity of 1.45 W/mK at 1,073 K. This resulted in the highest ZT of 0.29 at 1,073 K. From the optical absorption spectra, the electronic structure near the Fermi level show no significant change with Ga doping.