Chemical Expansion and Change in Lattice Constant of Y‐Doped BaZrO3 by Hydration/Dehydration Reaction and Final Heat‐Treating Temperature

Knowledge of thermal behavior of electrolyte is important for fuel cell fabrication. In this study, using high‐temperature X‐ray diffraction analysis (HT‐XRD) and thermo‐mechanical analysis (TMA), a systematic investigation of lattice constants was performed on Y‐doped BaZrO₃, which is a promising candidate for electrolyte in protonic ceramic fuel cells. The results revealed that a chemical expansion was observed between 300°C and 450°C during the heating process in HT‐XRD, and was attributed to the dehydration of BZY. Furthermore, it was found that the lattice constants of the samples doped with Y, Sm, Eu, and Dy were larger for the ones finally heat‐treated at 1600°C for sintering than those heat‐treated at 1300°C for synthesizing. The similar behavior was not observed in Sc‐doped samples.     

A competitive particle swarm optimizer and its application to wireless sensor networks

In this paper, a simple competitive particle swarm optimizer for finding plural acceptable solutions is proposed. In the proposed algorithm, particles are divided into plural groups corresponding to the required number of solutions. The groups simultaneously search for solutions in their own priority search regions. These regions prevent the different groups from searching for the same solutions. The proposed algorithm can effectively find desired plural acceptable solutions without introducing complex judgments for convergences to each solution and without increasing the number of search iterations. Also, the proposed algorithm can easily control distances between these solutions by adjusting a single additional parameter. Through numerical experiments, the effectiveness of the proposed algorithm is verified. In addition, the proposed algorithm is applied to a problem in wireless sensor networks. It is shown that obtained results can contribute to prolonging lifetime of such networks. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

On the structural origin of the catalytic properties of inherently strained ultrasmall decahedral gold nanoparticles

A new mechanism for reactivity of multiply twinned gold nanoparticles resulting from their inherently strained structure provides a further explanation of the surprising catalytic activity of small gold nanoparticles. Atomic defect structural studies of surface strains and quantitative analysis of atomic column displacements in the decahedral structure observed by aberration corrected transmission electron microscopy reveal an average expansion of surface nearest neighbor distances of 5.6%, with many strained by more than 10%. Density functional theory calculations of the resulting modified gold d-band states predict significantly enhanced activity for carbon monoxide oxidation. The new insights have important implications for the applications of nanoparticles in chemical process technology, including for heterogeneous catalysis.     

The Na(+)-K(+)-ATPase beta 1 subunit is associated with the HK alpha 2 protein in the rat kidney

The Na-K-ATPase beta 1 subunit acts as the beta subunit for the HK alpha 2 protein in the rat kidney. The colonic H(+)-K(+)-ATPase is a member of the P-type ATPases, and has been shown to contribute to potassium transport by the mammalian kidney and colon. The P-type ATPases often consist of an alpha subunit that contains the catalytic site and a beta subunit that participates in regulation of enzyme activity and targeting of the enzyme to the plasma membrane. The cDNA of the alpha subunit (HK alpha 2) has been cloned and the HK alpha 2 protein has been isolated from the rat kidney and colon. However, a unique beta subunit for the colonic H(+)-K(+)-ATPase has not been described. To determine if one of the known beta subunits present in the kidney might act as the beta subunit for the colonic H(+)-K(+)-ATPase, microsomes enriched in the colonic H(+)-K(+)-ATPase were isolated using an HK alpha 2-specific antibody (AS 31.7) and the Minimac magnetic separation system. Immunoblots of rat kidney microsomal protein isolated with antibody AS 31.7 were probed with antibodies directed against the gastric HK beta subunit, Na(+)-K(+)-ATPase alpha 1, and Na(+)-K(+)-ATPase beta 1 subunits. A band of the appropriate size was detected with Na(+)-K(+)-ATPase beta 1-specific antibodies, but not those directed against HK beta 1. These data suggest that Na(+)-K(+)-ATPase beta 1 could be the beta subunit for the colonic H(+)-K(+)-ATPase in the kidney.     

Influence of thermal properties of zirconia shroud on analysis of PHEBUS FPT0 bundle degradation test with ICARE2 code

In the FPT0 test of the PHEBUS/FP program, it was observed that the fraction of liquefied UO₂ reached 50%, which is much larger than the expected maximum value of 20%. Most of the post-test analyses with various computer codes underpredicted the bundle temperature during a late phase and could not reproduce such a large core degradation. In most of the previous analyses, the shroud thermal conductivity evaluated based on the Pears' ZrO₂ specific heat data and the thermal diffusivity measured by JAERI was used. However, recent thermal property data books adopt a lower specific heat than measured by Coughlin and King's at high temperature. The present analyses with ICARE2 showed that the FPT0 bundle behavior could be mostly reproduced by using the shroud thermal conductivity based on Coughlin and King's. If the present calculation is assumed to be correct enough, the shroud thermal conductivity at high temperature could be smaller than the current evaluation based on the Pears' data. Since the shroud thermal conductivity has thus a strong effect on the bundle behavior, further measurement and evaluation of the thermal properties of the shroud are highly recommended.     

Gene therapy by in vivo interferon-gamma gene transfer to murine bladder tumor

For the clinical application of the cytokine gene therapy, the antitumor effects of systemic administration of Interferon-gamma (IFN-gamma) and those of in vivo direct IFN-gamma gene transfer to the tumors of mouse bladder carcinoma (MBT2) were compared. After the subcutaneous inoculation of MBT2 cells into mice, 10(2), 10(3) or 10(4) units of IFN-gamma were injected intraperitoneally (i.p.) or subcutaneously (s.c.). Neither i.p. nor s.c. injection of IFN-gamma resulted in tumor suppression or prolonged the survival time of tumor-bearing mice. The effect of in vivo direct IFN-gamma gene transfer by a retrovirus vector to MBT2 tumors was also evaluated. After the subcutaneous inoculation of MBT2 cells into mice, a virus culture supernatant containing IFN-gamma gene was injected into the same tumor site once a day for 3 days. In 50% of the mice in the treatment groups with IFN-gamma gene induction, no tumor formation was observed. Tumor-free survival and actuarial survival in the treatment groups were significantly longer than those in the control group. These results showed the possibility of in vivo direct IFN-gamma gene transfer into tumors and were encouraging for the execution of tumor cell-targeted IFN-gamma gene therapy against human bladder cancer.     

Nanosized Au Particles as an Efficient Cocatalyst for Photocatalytic Overall Water Splitting

The effect of the photodeposition of gold particles onto several photocatalysts on the photocatalytic activities was studied. The photocatalytic activities of K₄Nb₆O₁₇, Sr₂Nb₂O₇, KTaO₃ NaTaO₃, and NaTaO₃ doped with La for water splitting were improved when gold particles were deposited. The latter were nanoparticles, consistent with their surface plasmon absorption. The nanosized gold particle functioned as an efficient cocatalyst for photocatalytic water splitting by assisting H₂ evolution.     

Liquid flow in impeller region of an unbaffled agitated vessel with an angularly oscillating impeller

The characteristics of a liquid flow were studied in the impeller region of an unbaffled agitated vessel with an angularly oscillating impeller whose unsteady rotation proceeds while periodically reversing its direction at a set angle. The measurement of the velocity of the liquid flow was performed by particle tracking velocimetry (PTV), abreast of that of the torque of the shaft to which the impeller was attached. When a disk turbine impeller with six flat blades was used with variations in operating conditions, such as the frequency and amplitude of impeller angular oscillation, a series of images obtained during one oscillation cycle were analyzed to characterize the internal and discharge streams inside and outside the impeller rotational region. Energy data were inferred on the basis of the circumferential and radial velocities of an internal flow. Results showed that although the total head provided to the liquid by the impeller blades is almost similar, independent of the amplitude of impeller angular oscillation, namely, the acceleration of its movement, the transformation of energy from the pressure head to the velocity head is more efficient at a larger amplitude. In addition, the discharge flow was characterized in terms of volumetric flow rates calculated from the radial and axial velocities. The operation at a smaller amplitude was shown to transform the flow more successfully from the radial direction to the upward and downward axial directions near the vessel wall.