Graded evolution of anisotropic microstructure during sintering from crystal-oriented powder compact

Anisotropic sintering, including shrinkage and grain growth, was examined for c-axis-oriented (Sr,Ca)₂NaNb₅O₁₅ (SCNN) ceramics, which were prepared by colloidal processing under a magnetic field. In the c-axis-oriented SCNN powder compact, shrinkage and grain growth along the c-axis were higher than those along the a-axis. The anisotropic microstructural development was clearly associated with anisotropic sintering shrinkage. X-ray diffraction, scanning electron microscopy, and energy back scattering diffraction showed that the grain growth of oriented particles by including random grains contribute to the development of the oriented microstructure. Finally, the highly crystal-oriented SCNN ceramics with a densified microstructure were obtained through anisotropic sintering. These results clearly showed the potential to develop a well-defined anisotropic microstructure during sintering by designing and controlling the particle packing structure in a powder compact.     

Vapor absorption by LiBr aqueous solution in vertical smooth tubes

Heat and mass transfer in a falling film vertical in-tube absorber was studied experimentally with LiBr aqueous solution. The presented results include the effect of solution flow rate, solution subcooling and cooling water temperature on the absorption in a smooth copper tube 16.05 mm I.D. and 400 mm long. The experimental data in the previous report for a 1200-mm-long tube was also re-examined and compared. It was demonstrated by the observation of the flow in the tube that the break down of the liquid film into rivulets leads to deterioration of heat and mass transfer at lower film Reynolds number or in longer tubes. An attempt to evaluate physically acceptable heat and mass transfer coefficients that are defined with estimated temperature and concentration at the vapor–liquid interface was also presented.     

Preparation of pyrochlores. A1−xHxTaO3·nH2O (A=Na,K)

Pyrochlores of A_1?xH_xTaO₃·nH₂O (A=Na,K) were prepared under the hydrothermal conditions. The values of x for these compounds were increased from 0.3 to 0.5 for A=Na and from 0.2 to 0.5 for A=K by treatment with the distilled water. The compounds with x<0.5 were decomposed to a mixture of NaTaO₃ and Na₂Ta₄O₁₁ for A=Na, or to a mixture of KTaO₃ and a tetragonal tungsten bronze phase, and those with x=0.5 to a single phase of A₂Ta₄O₁₁ at elevated temperatures. Below the decomposition temperatures, defect pyrochlores with oxygen vacancies, $\text{A}{}_{\mathrm{<mtext>1?</mtext><mtext>x</mtext>}}\text{TaO}{}_{\mathrm{<mtext>3?</mtext><mtext>x</mtext><mtext>2</mtext>}}$, were produced. They were hygroscopic, and in the case of A=K and x=0.5 the original phase was recovered by leaving in air for several hours.     

Antigenic and genetic diversities of Babesia ovata in persistently infected cattle

Exploring the antigenic and genetic diversities of Babesia ovata, we obtained several field isolates from grazing cattle in the Okushiri island, Japan. Parasite isolation was greatly facilitated by using bovine red blood cell-substituted SCID mice (Bo-RBC-SCID mice), into which the blood samples of the cattle were inoculated. Isolates from different individuals within a herd of cattle were compared in immunoblot analysis with an anti-B. ovata serum and also in Southern blot analysis with a probe for the small subunit ribosomal RNA gene. In both analyses, the isolates exhibited banding patterns that were significantly different from each other. We were also able to obtain a series of parasite isolates from a single cow in different seasons of a nine months period, including winter when active vector ticks were not in the field environment. Different seasonal isolates showed different banding patterns in both immunoblot and Southern blot analyses. By contrast, these analyses detected little difference among the parasites that had been passed various times in Bo-RBC-SCID mice, where no specific immune responses should be generated. These results indicate that individual animals within a herd of cattle were infected with antigenically and genetically diversified populations of B. ovata, and that the parasites could persistently infect a single animal with dynamic change in their predominant subpopulations.     

66/77-kV C-GIS using composite insulation in SF6 gas

A second-generation model of cubicletype gas-insulated switchgear (C-GIS) with composite insulation incorporating SF₆ gas has been developed. The design does not require a gas process in field assembly; it has high reliability and its installation is more rapid; and a further reduction in size is achieved. The design principles are described in detail.     

Carcinosarcoma of the rectosigmoid colon: report of a case

We report an unusual case of carcinosarcoma of the colon. An 80-year-old woman was admitted to our hospital with lower abdominal pain. Computed tomography showed a large pelvic mass, 18cm in maximal diameter, and barium enema and colonoscopy both showed a type-2 tumor in the sigmoid colon. We performed Hartmann's procedure with resection of the ileocolic segment. Immunohistochemical stains of the resected specimen revealed that most of the tumor consisted of spindle cell sarcoma with neural and muscle differentiation, while only the superficial area of an ulcerated lesion contained adenocarcinoma positive for carcinoembryonic antigen. The patient died of a fast-growing recurrent pelvic tumor 6 months postoperatively. Our experience of this case and our review of eight other cases in the English literature indicate that wide resection provides the best chance of cure, but careful postoperative follow-up is essential.     

FDTD analysis of switching characteristics in magnetooptic functional devices using magnetostatic surface waves

Collinear magnetooptic interaction with magnetostatic surface waves (MSSW) can be used for wavelength‐selective switches, wavelength filters, and frequency shifters in wavelength‐division‐multiplexed (WDM) photonic networks and optical processing systems. The switching efficiency can be improved with a multilayer waveguide structure. To investigate the dynamic switching characteristics, the FDTD method was employed. The mode conversion between TE and TM mode was successfully demonstrated with FDTD simulation. The filtering characteristics were also evaluated. The FDTD results were compared with the result from the coupled mode theory, and good agreement was obtained. Switching of an optical pulse was also demonstrated by the FDTD method. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(1): 40–47, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20501     

Twin-Related Tetragonal Variants in Yttria Partially Stabilized Zirconia

Crystals of yttria partially stabilized zirconia were grown by the arc-image floating-zone technique and studied by transmission electron microscopy. Crystals annealed at 1700°C consist of tetragonal precipitates and a cubic matrix. The platelike domains in a precipitate are twin-related tetragonal variants stacked alternately parallel to the (011) twin plane. The axial relations between the tetragonal precipitate and the cubic matrix are [100]_tetragonal|[100]_cubic, [011]_tetragonal|[011]_cubic.     

Inhibition by dexamethasone of human neutrophil apoptosis in vitro

The efficacy of collagen-sponge to reduce postoperative scar formation was investigated in 65 Japanese white rabbits that received laminectomy in the 7th and 8th thoracic vertebra. The defect after laminectomy was filled by collagen-sponge in 25 rabbits, by free fat in 20 rabbits, and by nothing in 20 rabbits as controls. The animals were sacrificed 2, 4, 8 and 12 weeks and additional 5 rabbits of which defects were filled with collagen-sponge were sacrificed after 24 weeks. All the defects were examined histologically. At 4 weeks after laminectomy, the defects filled by collagen-sponge showed that fibrous tissue had invaded into the sponge, but there was no remarkable adhesion to the dura mater. At 8 weeks, the defect with collagen sponge showed foaming cells, and no thickening of the dura mater was observed. At 12 weeks, the grouping of foaming cells was partially replaced by fat cells. At 24 weeks, most of the foaming cells were replaced by fat cells, and the defect was then similar to that filled by free fat at 12 weeks. In contrast, the defect with no interposed membrane was already filled with fibrous tissue at 4 weeks, and adhesion to the dura mater was observed. Although the free-fat graft at 12 weeks postoperatively showed no remarkable adhesion around the dura mater, infiltration of fat tissue into the spinal canal was observed in 2 of 5 rabbits. These results indicated that collagen-sponge can be utilized as a new biomaterial to effectively prevent scar formation after laminectomy.