Thermal stability of reinforced Nb3Sn composite superconductor under cryocooled conditions

Several types of reinforced Nb₃Sn wires have been developed to prevent reduction of superconducting properties by applying a strong electromagnetic force. To fabricate a cryocooled magnet using those reinforced wires, we experimentally measured the minimum quench energy (MQE) under cryocooled conditions of some reinforced Nb₃Sn wires. As a result, it became clear that thermal stability expressed as MQE was controlled by the temperature margin between the temperature of the operating condition and the transition temperature from superconductivity to normal. Using the FEM analysis, it was realized that the cause of the decline in thermal stability for the reinforced wires was the low thermal conductivity of the reinforced materials.     

Determination of three dimensional in situ stress from core discing based on analysis of principal tensile stress

To determine all of the components of in situ stress from core discing, both the directions and magnitudes of the principal in situ stresses must be determined for a disc of a given thickness. In this study, we analyzed the direction and magnitude of tensile stress below an HQ core stub for 11 core lengths using stress conditions under which core discing is likely to occur. First, based on an analysis of the direction of tensile stress below the core stub, we propose a method for determining directions of in situ stress from the height distribution at the periphery of the end surface of a disc. This method can be used with a disc of any thickness. Next, based on an analysis of the magnitude of tensile stress in the central part of a core, we propose a linear criterion for core discing, which can be applied to a core of any length. This criterion was in good agreement with an empirical formula obtained previously in laboratory experiments. By combining information on the direction of in situ stress and the linear criterion for core discing, we propose a method for determining all of the components of in situ stress from core discing under the assumption that vertical stress is given by the overburden stress. Finally, these methods were applied to discs obtained from a field where hydraulic fracturing was performed to measure horizontal stresses. The results showed that the azimuths of the principal stresses estimated from core discing were consistent with those of the principal horizontal stresses determined by hydraulic fracturing and that while the magnitudes of the principal horizontal stresses estimated from core discing showed a large scatter, they were similar to those determined by hydraulic fracturing.     

Development of 170 GHz/500 kW gyrotron

A development of 170GHz/500kW level gyrotron was carried out as R&D work of ITER. The oscillation mode is TE_31,8. In a short pulse experiment, the maximum power of 750kW was achieved at 85kV/40A. The efficiency was 22%. In the depressed collector operation, 500kW/36%/50ms was obtained. The maximum efficiency of 40% was obtained at P_RF=470kW whereas the power decrease by the electron trapping was observed. Pulse extension was done up to 10s at P_RF=170kW with the depressed collector operation. The power was limited by the temperature increase of the output window.     

A new voltage control equipment using fuzzy inference

Power system control equipment needs higher sensitivity and operational reliability. Advanced voltage control equipment is needed for reducing the frequency of tap changes and improving the characteristics (the relationship between the actual voltage and reference voltage) of the voltage to meet today's power system requirements. However, these objectives are in a trade-off relationship. Studies of voltage control derived from a knowledge base suitable for electric power systems can satisfy these objectives using fuzzy inference. Compared with corresponding conventional equipment, the new equipment improved the deviation of 30 min average voltage of 30 percent. This paper describes the design concept of new voltage control equipment using fuzzy inference. In addition, field test results are described along with rules of fuzzy inference, membership functions, and the deviation of 30 min average voltage through detailed simulation.     

Direct Spectroscopic Determination of Europium(Ⅱ) Concentration During Europium(Ⅲ) Electro-Reduction in Hydrochloric Acid Medium

UV-Vis spectroscopy was used to directly determine the concentration of Eu(Ⅱ) during electroreduction of Eu(Ⅲ) in hydrochloric acid medium. Electroreduction was carried out in a flow type electrolyzer with glassy carbon cathode at the constant potential of -800 mV vs. Ag/AgCl. The effects of oxygen and concentration of hydrochloric acid on the system were investigated. For 0.01 mol·L-1 hydrochloric acid, calibration curves for Eu(Ⅱ) absorption bands at 248 and 320 nm were constructed. Molar absorption coefficients were estimated to be 2016 and 648 L·mol-1·cm-1, respectively. The absorbance strongly decreased with decrease in pH of the solution, whereas concentration of chloride had only a negligible effect.     

Alzheimer’s Disease Animal Models: Elucidation of Biomarkers and Therapeutic Approaches for Cognitive Impairment

Alzheimer’s disease (AD) is an age-related and progressive neurodegenerative disorder. It is widely accepted that AD is mainly caused by the accumulation of extracellular amyloid β (Aβ) and intracellular neurofibrillary tau tangles. Aβ begins to accumulate years before the onset of cognitive impairment, suggesting that the benefit of currently available interventions would be greater if they were initiated in the early phases of AD. To understand the mechanisms of AD pathogenesis, various transgenic mouse models with an accelerated accumulation of Aβ and tau tangles have been developed. However, none of these models exhibit all pathologies present in human AD. To overcome these undesirable phenotypes, APP knock-in mice, which were presented with touchscreen-based tasks, were developed to better evaluate the efficacy of candidate therapeutics in mouse models of early-stage AD. This review assesses several AD mouse models from the aspect of biomarkers and cognitive impairment and discusses their potential as tools to provide novel AD therapeutic approaches.     

Simple chemical syntheses of TAG monohydroperoxides

For the purpose of synthesizing standards to be used in the quantification of TAG hydroperoxides, three TAG (1,2-dioleoyl-3-palmitoylglycerol, 1-oleoyl-2-linoleoyl-3-palmitoylglycerol, and triolein) monohydroperoxides were chemically synthesized as authentic specimens. TAG were prepared by using a simple condensation in pyridine of glycerol and the corresponding acid chlorides. These TAG were then converted into monohydroperoxides by a photosensitized peroxidation. The synthesized monohydroperoxides were analyzed by normal-phase and RP-HPLC. The results of normal-phase HPLC analysis showed that monohydroperoxides from a corresponding TAG were a mixture of regioisomers. In RP-HPLC, however, the regioisomers of monohydroperoxides were not separated and gave a single peak, which may improve the sensitivity for the detection of TAG monohydroperoxides. In this study TAG monohydroperoxide standards were synthesized; these will be useful for the study of yet unknown biological and pathological roles of TAG hydroperoxides.     

Isotachophoretic analysis of surfactants

The qualitative and quantitative determination of anionic surfactants (sodium and lithium alkylsulfate, sodium dodecylbenzenesulfonate, sodium di-2-ethylhexyl sulfosuccinate, sodium and lithium perfluoroalkylcarboxylate, and lithium perfluorooctanesulfonate) were investigated by a capillary tube isotachophoresis using a potential gradient detector. The leading electrolyte solution was the mixture of acetonitrile and aqueous solution of histidine buffer containing calcium chloride. The terminating electrolyte solution was the aqueous solution of sodium octanoate. These electrolytes were effective for the analysis of the mixtures of strongly acidic surfactants.     

Effect of pressure on phase transition and morphology of bulk poly(trans-1,4-butadiene)

The effect of pressure on the melting, solid-solid transition, and crystallization of poly(trans-1,4-butadiene) (PTBD) was investigated using the pressure range of 1–3000 kg/cm². D.t.a. measurements showed that, the melting and transition temperatures increase with increasing pressure, whose pressure coefficients are 38°C per 1000 kg/cm² and 22°C per 1000 kg/cm², respectively. These values were in fairly close agreement with those calculated from the Clausius-Clapeyron equation. Morphological studies using electron microscope and small-angle X-ray scattering method revealed that, the samples crystallized with relatively small supercoolings under normal or high pressure, are formed of distinct lamellae 400–800 Å thick. The lamellar thickness was inappreciably dependent on crystallization pressure. The significant effect of pressure on crystallization was recognized in a tendency of the crystallinity to increase, with increasing crystallization pressure. This pressure effect was explained by the mechanism that, the increased pressure might make the packing of molecular chains in liquid, more dense and that the secondary crystallization might be accelerated, to increase the lateral dimensions of lamellae.     

Link Prediction based on Structural Properties of Online Social Networks

Question-Answering Bulletin Boards (QABB), such as Yahoo! Answers and Windows Live QnA, are gaining popularity recently. Questions are submitted on QABB and let somebody in the internet answer them. Communications on QABB connect users, and the overall connections can be regarded as a social network. If the evolution of social networks can be predicted, it is quite useful for encouraging communications among users. Link prediction on QABB can be used for recommendation to potential answerers. Previous approaches for link prediction based on structural properties do not take weights of links into account. This paper describes an improved method for predicting links based on weighted proximity measures of social networks. The method is based on an assumption that proximities between nodes can be estimated better by using both graph proximity measures and the weights of existing links in a social network. In order to show the effectiveness of our method, the data of Yahoo! Chiebukuro (Japanese Yahoo! Answers) are used for our experiments. The results show that our method outperforms previous approaches, especially when target social networks are sufficiently dense.