Development of Reference Shunt for Short‐Time Alternating High Current Tests and Study of Measuring System

Short‐circuit tests for power circuit breakers and others require alternative short‐time current measurement, from a few kA to over several tens kA. However, the reference measurement system as a national standard or a specified secondary standard instrument to directly perform comparative test as a complete calibration test in high current class has not yet been established globally. The Japan Short‐Circuit Testing Committee (hereinafter referred to as “JSTC”) has therefore developed a shunt resistor that can be used as a standard instrument for high current measurement. Reference system using this shunt resistor is also considered by JSTC. The performance of the newly developed shunt resistor has been checked through several methods, such as resistance measurement, high power current test, high frequency current test, temperature rise test, and interference test. The results of the tests proved satisfactory performance. Resistance of the shunt resistor before and after the tests was invariant and stable. This makes the shunt resistor adequate for a reference in practical use. In addition, evaluation of uncertainty of the whole reference system including this shunt resistor satisfactorily fulfills the requirements of IEC 62475 edition 1.0, 2010.     

Physical Properties of Soy Bean and Broad Bean 11S Globulin Gels Formed by Transglutaminase Reaction

Physical properties of transglutaminase-induced glycinin and legumin gels were compared with thermally induced gels. Results of deformation tests showed that transglutaminase-induced gels were more rigid and elastic than thermally induced gels. From creep compliance tests, all elastic moduli and viscosities except Newtonian viscosity were higher for transglutaminase-induced gels. Electron micrographs revealed that network structures of transglutaminase-induced gels were composed of larger unit particles forming more developed strands and clusters. More rigid and elastic gels were formed from glycinin as compared to legumin by both gelling methods.     

Preparation and characterization of glass composite using metal particles coated with semiconductive SnO2 fine particles obtained via sol—gel method

SnO₂—glass composites are promising materials for nitrogen-fireable thick film resistor systems. However, the SnO₂—glass composite has many undesirable properties which should be improved for industrial application, such as a high electrical resistivity and a large negative temperature coefficient of electrical resistance. This work was undertaken to make a survey of the methods for improvement in the electrical properties of the SnO₂—glass composites. The effect of the addition of Cu particles, with a large positive temperature coefficient of electrical resistance, on the electrical properties of SnO₂—glass composites has been investigated. Cu particles have been coated with semiconductive SnO₂ fine particles by hydrolysing tin and antimony ethoxides then firing. The coated particles have been applied as conductive components in the glass composite. Using SnO₂-coated Cu particles, Cu and SnO₂ particles are homogeneously dispersed in a glass matrix, and the electrical properties of the glass composites largely depend on the volume fraction of Cu in the glass composite. The volume fraction of Cu in the glass composite is determined by a Cu/SnO₂ volume ratio in the coated particles. From the experimental evidence, it is thought feasible to produce the glass composite having well-controlled electrical properties by the suitable selection of the Cu/SnO₂ ratio in the coated particles. This revised version was published online in July 2006 with corrections to the Cover Date.     

Non-linear analysis of nitrogen cycle in aquatic ecosystems

In this paper, s mathematical model of the nitrogen cycle in aquatic ecosystems is proposed for studying eutrophication in bodies of water. It is presented that for some parameter values all equilibrium states of the system become unstable and a stable limit cycle appears. This is explained by a Hopf bifurcation. The conditions under which the Hopf bifurcation occurs are obtained by the detailed analysis of the model. Some results of numerical computations are also presented.     

Thermal Gelation Mechanism of Legumin from Broad Beans

The legumin formed a gel through formation of soluble aggregates and their juncture. Electron microscope studies indicated the legumin molecules associated to form strands. These strands then formed network-like structures, finally resulting in gel formation. The thickness of those strands and network constituents was irregular (8.3 to 36 nm). A presumed process of thermal legumin gelation was hypothesized. A comparison of gelation behaviors in legumin and in glycinin was also studied.     

Measurement of soft X-ray absorption spectra and elemental analysis in local regions of mammalian cells using an electronic zooming tube

Direct measurement of absorption spectra for minute areas (2 μm ×2 μm) in a dried mammalian cell was attempted using X-ray contact images of a whole cell. The wavelength region used ranged from 1.5 to 10 nm covering the absorption edges of the major cellular elements. The measurements were achieved taking advantage of synchrotron radiation as a tuneable light source and an electronic zooming tube as an X-ray detector with a high spatial resolution. The spectra in every intracellular area exhibited marked absorption changes at the absorption edges of carbon, nitrogen and oxygen, while minor but significant changes for iron and calcium were observed, particularly in the cytoplasmic areas. These results reveal the different spatial distributions of the constituent elements in a cell.     

Image contrast enhancement of Ni/YSZ anode during the slice‐and‐view process in FIB‐SEM

Focused ion beam‐scanning electron microscopy (FIB‐SEM) is a widely used and easily operational equipment for three‐dimensional reconstruction with flexible analysis volume. It has been using successfully and increasingly in the field of solid oxide fuel cell. However, the phase contrast of the SEM images is indistinct in many cases, which will bring difficulties to the image processing. Herein, the phase contrast of a conventional Ni/yttria stabilized zirconia anode is tuned in an FIB‐SEM with In‐Lens secondary electron (SE) and backscattered electron detectors. Two accessories, tungsten probe and carbon nozzle, are inserted during the observation. The former has no influence on the contrast. When the carbon nozzle is inserted, best and distinct contrast can be obtained by In‐Lens SE detector. This method is novel for contrast enhancement. Phase segmentation of the image can be automatically performed. The related mechanism for different images is discussed.     

Apparent Heat Transfer in a Forced Convection Oven and Properties of Baked Food

Parameters for expressing the heating performance and baking results of sponge cakes dependent on heating performance in a forced convection oven were studied. The heating performance of a forced convection oven may be expressed by the apparent heat transfer coefficient which was measured at various air temperatures and velocities. Both the air velocity and temperature of the circulating air affected the apparent heat transfer coefficient in a forced convection oven and determined the final properties of the baked food. The effects of these parameters on sponge cakes baked in the forced convection oven were observed.     

TEXTURAL PROPERTIES OF STARCH GELS FILLED WITH COLLAGEN AND CHITIN

Chitin and collagen powders were added as fillers to various starches (potato, sweet potato, kudzu, corn, wheat, and mung bean), heated at 100C for 10 min with stirring to make a hot paste and allowed to gel quiescently at 5C for 2 h in order to investigate the effects of the filler particle on the texture of the gels. The parameters of hardness, cohesiveness and adhesiveness were determined instrumentally and compared. The filler particles of collagen and chitin were effective in increasing hardness of corn starch gels but had no effects on hardness of the potato, sweet potato, kudzu, wheat and mung bean starch gels except at the lower starch concentrations. Cohesiveness was increased slightly in all starch gels by addition of collagen whereas chitin addition only increased the cohesiveness of sweet potato and mung bean starch gels. Collagen and chitin addition increased adhesiveness all of starch gels, but the intensity of the effect was most remarkable for collagen. The observed differences in effects was apparently due to differences in the interactions between starches and filler particles arising from differences in the surface properties of the filler particles.