Josephson plasma resonance in Bi2Sr2CaCu2O8+δ under parallel magnetic field

Josephson plasma resonance in under-doped Bi ₂ Sr ₂ CaCu ₂ O ₈₊ single crystals has been observed when magnetic field is applied parallel to the ab plane and its vicinity. The resonance mode splits into two branches at higher and lower temperature regions, and a definite gap appears in the temperature region between them. As the magnetic field is tilted from the ab plane, these branches come closer and finally merge to a single mode. This leads to a general interpretation that the resonance mode observed in a parallel field may be due to continuous extension of the c axis plasma mode. However, splitting of the mode as well as the peculiar temperature dependence of the resonance field, the line shape, and its intensity strongly imply that these behaviors may originate from the inherent resonance modes in parallel field. In particular, the high temperature mode fields goes even higher in temperature beyond the zero field resonance as the field increases, suggesting that a new explanation may be required for the case of parallel magnetic field.     

Determination of dioxins and polychlorinated biphenyls in breast milk, maternal blood and cord blood from residents of Tohoku, Japan

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) are bioaccumulative chemicals that are considered to be toxic contaminants based on several epidemiological studies. To elucidate exposure levels of these chemicals in the present study, concentrations of PCDD/DFs, dioxin-like PCBs (DL-PCBs) and PCBs in breast milk, maternal blood and cord blood obtained from the same participants registered in a birth cohort study in Tohoku, Japan, were measured. Congener-specific analysis revealed several differences in minor congeners of these compounds among the three specimen types, although major congeners were detected in the specimens. The toxicity equivalence quantity concentrations (1998 WHO-TEF) and PCBs in breast milk, maternal blood and cord blood on the whole and on a lipid basis were in the order of breast milk > maternal blood > cord blood. Pearson's correlation coefficients of TEQs and total PCBs among the three specimens were high, with the correlation coefficient of TEQ between breast milk and maternal blood being the highest (r=0.94, p<0.001). On the other hand, the TEQ between breast milk and cord blood was the lowest (r=0.79, p<0.001). Pearson's correlation coefficient between the TEQ and PCBs in each specimen was also high (r=0.82-0.95, p<0.001). The associations of chemical concentrations with maternal age, parity, fish intake, BMI and the rate of body weight increase during pregnancy were analyzed with multiple linear regression analysis. TEQ concentrations and PCBs were negatively associated with parity (p<0.05), and maternal age was positively associated with PCBs (p<0.05). However, the associations with BMI and fish intake during pregnancy were not significant. These results suggest that parity is an important factor affecting the concentrations of dioxins and PCBs in these specimens.     

Role of hydrogen environment induced hydrogen embrittlement of Ti–8Al–1Mo–2V alloy

Structural analysis by mean of metallographic, SEM fractographic and TEM replica technique including acoustics-emission studies have been carried out on Ti–8Al–1Mo–2V alloy specimen tested at room temperature in gaseous hydrogen environment. The result provided evidences of the presence of face centred cubic titanium hydride at the fracture surfaces, with discontinuous nature of crack propagation. The present work confirmed that an essentially continuous path of β phase is necessary for the occurrence of slow crack growth in gaseous hydrogen. Metallographic and fractographic observation leave little doubt that cracks propagates along the α–β interface rather than through stable α phase.     

Improvement of response characteristics of TiO2 humidity sensors by simultaneous addition of Li2O and V2O5

Porous TiO₂ ceramics were prepared by adding various amounts of Li₂O and V₂O₅ and the humidity sensitivity of the resulting ceramics was investigated by means of electrical measurements, scanning electron microscopy and mercury intrusion porosimetry. Simultaneous addition of Li₂O and V₂O₅ to TiO₂ enabled sintering at temperatures as low as 700 °C and also decreased the impedance of the ceramics. Furthermore, in the ceramics including these additives simultaneously, excellent humidity sensitivity as well as good response characteristics were observed. The microstructures of these ceramics depended on the firing temperature and the amount and ratio of Li₂O/V₂O₅, and optimum humidity sensitivity was observed for the sample including both 0.25 mol% Li₂O and 0.75 mol% V₂O₅ fired at 700 °C. These results indicated that the humidity sensitivity and its response characteristics were closely related to the microstructure, and that improving the uniformity of microstructure is important for improving humidity sensitivity and its response characteristics.     

Molecular characterization of the PEX5 gene encoding peroxisomal targeting signal 1 receptor from the methylotrophic yeast Pichia methanolica

In this study, we describe the molecular characterization of the PEX5 gene encoding the peroxisomal targeting signal 1 (PTS1) receptor from the methylotrophic yeast Pichia methanolica. The P. methanolica PEX5 (PmPEX5) gene contains a open reading frame corresponding to a gene product of 646 amino acid residues, and its deduced amino acid sequence shows a high similarity to those of Pex5ps from other methylotrophic yeasts. Like other Pex5ps, the PmPex5p possesses seven repeats of the TPR motif in the C-terminal region and three WXXXF/Y motifs. A strain with the disrupted PEX5 gene (pex5Delta) lost its ability to grow on peroxisome-inducible carbon sources, methanol and oleate, but grew normally on glucose and glycerol. Disruption of PmPEX5 caused a drastic decrease in peroxisomal enzyme activities and mislocalization of GFP-PTS1 and some peroxisomal methanol-metabolizing enzymes in the cytosol. Expression of the PmPEX5 gene was regulated by carbon sources, and it was strongly expressed by peroxisome-inducible carbon sources, especially methanol. Taken together, these findings show that PmPex5p has an essential physiological role in peroxisomal metabolism of P. methanolica, including methanol metabolism, and in peroxisomal localization and activation of methanol-metabolizing enzymes, e.g. AOD isozymes, DHAS and CTA.     

Image‐Based Crack Detection for Real Concrete Surfaces

In this paper, we introduce a novel image‐based approach to detect cracks in concrete surfaces. Crack detection is important for the inspection, diagnosis, and maintenance of concrete structures. However, conventional image‐based approaches cannot achieve precise detection since the image of the concrete surface contains various types of noise due to different causes such as concrete blebs, stain, insufficient contrast, and shading. In order to detect the cracks with high fidelity, we assume that they are composed of thin interconnected textures and propose an image‐based percolation model that extracts a continuous texture by referring to the connectivity of brightness and the shape of the percolated region, depending on the length criterion of the scalable local image processing techniques. Additionally, noise reduction based on the percolation model is proposed. We evaluated the validity of the proposed technique by using precision recall and receiver operating characteristic (ROC) analysis by means of some experiments with actual concrete surface images. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Design Estimation of the Hybrid Power Source Railway Vehicle based on the Multiobjective Optimization by the Dynamic Programming

The power source of hybrid railway vehicles consists of both generation and energy storage devices. The hybrid vehicles have a high degree of freedom in the system design because they have different power sources. Therefore, it is difficult to establish generalized design methods of the power system. Various patterns of device capacities of generation and energy storage equipments are available for the hybrid vehicle. And various types of power control strategies are also selectable. With this background, this paper proposes a globally searched design estimation method for hybrid vehicles, which is based on multiobjective optimization by dynamic programming. The proposed method enables us to globally clarify the optimal candidates in accordance with various railway lines from a wide search domain. This results in various design concepts of the hybrid vehicles. Then, this paper confirms that the proposed method provides effective design guidelines for the conceptual design of the hybrid vehicles. Therefore the proposed method is useful for the design problem of hybrid vehicles that have a higher degree of freedom compared to electric railway vehicles. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Model for predicting performance of cooling fans for thermal design of electronic equipment (Modeling and evaluation of effects from electronic enclosure and inlet sizes)

This study describes the performance of cooling fans in terms of the P–Q curve and the maximum flow rate under various environmental conditions. It focuses on the relationship between fan performance and configuration factors such as the electronic enclosure. The presence of an enclosure wall increased the pressure characteristic of the fan performance. The presence of a narrow inlet decreased the flow rate. When the inlet area of the enclosure became smaller than twice the fan flow area, the flow rate was decreased. The maximum flow rate depended on the ratio of the inlet area to the fan flow area. A model for predicting pressure rise and flow rates in the enclosure is proposed. The model is used in a thermal analysis of a PCB model set in an enclosure. © 2011 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.20347     

Coupled-wave analysis of vector holograms: effects of modulation depth of anisotropic phase retardation

The diffraction properties of thick vector holograms were analyzed with the use of a simple coupled-wave theory. Two eigenpolarizations in the holograms were determined based on the dielectric perturbation, and diffraction efficiencies for the polarizations were calculated by applying the Kogelnik method. The results were compared with those simulated by the finite-difference time-domain method. As a result, it was demonstrated that the diffraction efficiencies calculated by the two methods are in good agreement for any incident polarization when the modulation depth of the anisotropic phase retardation is substantially smaller than the mean retardation. In addition, we confirmed that coupled-wave analysis provides reasonable accuracy for relatively large modulation in the case of Bragg incidence with eigenpolarization.     

Phase Transition of Josephson Vortices Under High Magnetic Fields up to 30 T in Heavily Overdoped YBa2Cu3O7−δ Single Crystals

We have measured the temperature and the magnetic-field dependences of the resistivity, ρ(T) and ρ(H), under magnetic fields parallel to the ab planes up to 30 T for fully oxidized YBa₂Cu₃O_7?δ single crystals. Above 11 T, ρ(T) showed a kink structure and successively a gradual transition toward the zero-resistivity. Below 9 T, the resistive transition was continuous. These results indicate the appearance of a slush regime.