Solid insulated switchgear and investigation of its mechanical and electrical reliability

SF₆ gas is widely employed in medium‐voltage switchgear because of its high insulation reliability and down‐sizing ability. However, SF₆ gas was placed on the list of greenhouse gases under the Kyoto Protocol in 1997. Since then, research on low‐SF₆ or SF₆‐free insulation has been carried out actively. Therefore, we focused on solid materials with higher dielectric strength than SF₆, and we have now developed solid insulated switchgear (SIS) that uses molding of all main circuits. A new epoxy casting material is used which contains a large amount of spherical silica and a small amount of rubber particles. This new material has high mechanical strength, high thermal resistance, high toughness, and also high dielectric strength because of direct molding of the vacuum bottle, as well as reduced size and high reliability. This paper describes the technology of the new epoxy casting material which makes possible SIS. In addition, mechanical and electrical reliability tests of SIS using a new epoxy resin were performed, and the effectiveness of the developed material and the mechanical and electrical reliability of the SIS were verified. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 174(4): 28–36, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21057     

The influence of organization of LbL films containing a silsesquioxane polymer on the electrochemical response of dopamine

This paper describes the construction, evaluation, and application of an electrochemical sensor for the determination of dopamine (DA) in the presence of ascorbic acid (AA) and uric acid (UA). Satisfactory results were achieved for the simultaneous determination of DA and UA, it was verified that it is possible to detect AA in the presence of DA, but high concentrations of AA interfere in detection of DA. The sensor was constructed using the layer-by-layer (LbL) technique with the modification of the surface of indium tin oxide coated glass (ITO) substrate with nanostructured films comprising a 3-n-propylpyridinium silsesquioxane polymer (SiPy⁺Cl^?) and nickel(II) tetrasulfophthalocyanine (NiTsPc). Using the square wave voltammetry technique (SWV), the LbL modified electrodes produced at different pHs (pH 2 and 8) were used to determine DA in the presence UA, and the electrochemical responses of the electrodes were compared. It was observed that the electrodes with the highest concentration of monomeric species showed the highest current intensity and the lowest peak potential for the DA and UA analytes in analysis of DA and UA, individually and simultaneously, with peak potential separation of 460 mV versus Ag/AgCl. Applying SWV, a linear dynamic range of 10–99 μmol L^?1 and 100–900 μmol L^?1 with detection limit of 16.8 μmol L^?1 and 58.3 μmol L^?1 was obtained for DA and UA, respectively. The method has good selectivity and sensitivity, and it was successfully applied to the simultaneous determination of DA and UA in spiked human urine sample.     

钢制防屈曲约束支撑的开发

作为消能减震部件,要求防屈曲约束支撑的滞回曲线稳定.开发了两块腹板式钢制防屈曲约束支撑SUB-H和螺栓组装式钢制防屈曲约束支撑SUB-X.结合开发试验,提出了SUB的结构设计公式.静态和动态荷载试验证明,SUB具有较高的安全性和精度,大型试验证明SUB在高轴力状态下也具有良好的滞回性能.     

Flocculating activity of cross-linked poly-gamma-glutamic acid against bentonite and Escherichia coli suspension pretreated with FeCl3 and its interaction with Fe3+

Cross-linked poly-gamma-glutamic acid (C-L gamma-PGA) at 5 microg/ml flocculated bentonite suspension pretreated with polyaluminum chloride (PAC) at 2 microg/ml Al3+-PAC to a transparency of approximately 30% after 30 min and more than 90% after 4 h, while Al3+ concentration in the upper phase of the suspension decreased with incubation time. When pretreated with FeCl3 at 16 microg/ml Fe3+-FeCl3, similar results were obtained. In the case of Escherichia coli suspension, the combination of C-L gamma-PGA and FeCl3 demonstrated a more marked flocculating activity with a satisfactory transparency occurring after 30 min of treatment, accompanied by a decrease in residual Fe3+ concentration. In the above two suspensions pretreated with FeCl3, small visible floats appeared in the early stage of incubation. These floats were found to be due to the direct interaction between FeCl3 and C-L gamma-PGA, indicating the formation of a water-insoluble complex. After allowing the suspension to stand for a long time, elemental analysis and inductively coupled plasma spectroscopy of the precipitates produced suggested that not only the complex was formed due to the interaction between Fe3+ in FeCl3 and COO- in the C-L gamma-PGA molecule, but also Fe2O3 and Fe(OH)3 might be entrapped in this complex. This could be applied to scavenge metal ions including Fe3+ from polluted water.     

Acid-base equilibria inside amine-functionalized mesoporous silica

Acid-base equilibria and effective proton concentration inside a silica mesopore modified with a trimethyl ammonium (TMAP) layer were studied by steady-state fluorescence experiments. The mesoporous silica with a dense TMAP layer (1.4 molecules/nm(2)) was prepared by a post grafting of N-trimethoxysilylpropyl-N,N,N-trimethylammonium at surfactant-templated mesoporous silica (diameter of silica framework =3.1 nm). The resulting TMAP-modified mesoporous silica strongly adsorbed of anionic fluorescence indicator dyes (8-hydroxypyrene-1,3,6-trisulfonate (pyranine), 8-aminopyrene-1,3,6-trisulfonate (APTS), 5,10,15,20-tetraphenyl-21H,23H-porphinetetrasulfonic acid disulfuric acid (TPPS), 2-naphthol-3,6-disulfonate (2NT)) and fluorescence excitation spectra of these dyes within TMAP-modified mesoporous silica were measured by varying the solution pH. The fluorescence experiments revealed that the acid-base equilibrium reactions of all pH indicator dyes within the TMAP-modified silica mesopore were quite different from those in bulk water. From the analysis of the acid-base equilibrium of pyranine, the following relationships between solution pH (pH(bulk)) and the effective proton concentration inside the pore (pH(pore)) were obtained: (1) shift of pH(pore) was 1.8 (ΔpH(pore)=1.8) for the pH(bulk) change from 2.1 to 9.1 (ΔpH(bulk)=7.0); (2) pH(pore) was not simply proportional to pH(bulk); (3) the inside of the TMAP-modified silica mesopore was suggested to be in a weak acidic or neutral condition when pH(bulk) was changed from 2.0 to 9.1. Since these relationships between pH(bulk) and pH(pore) could explain the acid-base equilibria of other pH indicator dyes (APTS, TPPS, 2NT), these relationships were inferred to describe the effective proton concentration inside the TMAP-modified silica mesopore.     

A phase-field simulation of uranium dendrite growth on the cathode in the electrorefining process

The uranium dendrite growth on the cathode during the pyroprocessing of uranium is investigated using a novel phase-field model, in which electrodeposition of uranium and zirconium from the molten-salt is taken into account. The threshold concentration of zirconium in the molten salt demarcating the dendritic and planar growth is then estimated as a function of the current density. Moreover, the growth process of both the dendritic and planar electrodeposits has been demonstrated by way of varying the mobility of the phase field, which consists of the effect of attachment kinetics and diffusion.     

Evaluation of the single yeast cell's adhesion to ITO substrates with various surface energies via ESEM nanorobotic manipulation system

Cell-surface adhesion force is important for cell activities and the development of bio materials. In this paper, a method for in situ single cell (W303) adhesion force measurement was proposed based on nanorobotic manipulation system inside an environment scanning electron microscope (ESEM). An end effector was fabricated from a commercial atomic force microscope (AFM) cantilever by focused ion beam (FIB) etching. The spring constant of it was calibrated by nanomanipulation approach. Three kinds of hydrophilic and hydrophobic ITO plates were prepared by using VUV-irradiation and OTS coating techniques. The shear adhesion strength of the single yeast cell to each substrate was measured based on the deflection of the end effector. The results demonstrated that the cell adhesion force was larger under the wet condition in the ESEM environment than in the aqueous condition. It also showed that the cell adhesion force to hydrophilic surface was larger than that to the hydrophobic surface. Studies of single cell's adhesion on various plate surfaces and environments could give new insights into the tissue engineering and biological field.     

Examination of original plant of mulberry bark extract, a natural food additive, based on composition of the constituents

Mulberry bark extract, a natural food additive, is described as a "root bark extract from Morus bombycis" (Japanese name: Yamaguwa) in the Notice (1996) relating to existing food additives used in Japan. The results of analyses by LC/UV and LC/MS suggested that the Mulberry bark extract products that were tested were actually made from the root bark of Morus alba (Japanese name: Maguwa) or its hybrid species, because the compositions of the constituents in the products are more similar to those in the extracts of the dried root bark of M. alba and hybrid species that are cultivated in Japan than to those of M. bombycis. In addition, the constituents of the food additive products were different from those of the natural medicine Mori Cortex products ('Souhakuhi' in Japanese) made from the root bark of mulberry grown in China, and which is described as being derived from M. alba in the Japanese pharmacopoeia. These results were also corroborated by Principal Component Analysis using the peak areas of LC/MS analysis as explanatory variables. After this study, it was decided that Mulberry bark extract is one of the existing food additives that should be excluded from the list this year in Japan.     

Brewer's yeast cell wall affects microbiota composition and decreases Bacteroides fragilis populations in an anaerobic gut intestinal model

Brewer's yeast cell wall (BYC) has been reported to have prebiotic activity that improves the microbiotal composition of the human gut. To understand the precise effect of BYC on gut microbiota and its metabolism, we used a three-stage continuous-flow reactor system that mimicked the environment of the large intestine. The reactor system was able to maintain the bacterial community stably for a week. The Bacteroides fragilis population decreased drastically after the addition of BYC into this system while the number of Lactobacillus was stably maintained. In addition, propionate and acetate levels increased drastically. This metabolic change correlated with an increase in a number of specific operational taxonomic units annotated to the genus Veillonella and Megasphaella. These results suggest that BYC affects the composition of microbiota in an in vitro model system.