Elsevier Science B.V.Acta Medica Okayama0167-577X65142011Effect of varying the ratio of matrix/dispersoid particle size on the piezoresistivity of alumina/carbon-black composite ceramics21972200ENAkiraKishimotoYutoTakagawaTakashiTeranishiHidetakaHayashiAlumina/carbon-black composite ceramics with different percolation thresholds were fabricated by changing the size ratio of constituent particles. The dependence of resistivity on pressure was established for each sample. The compositional dependence of resistivity can be explained by percolation theory. The percolation threshold decreases with increasing alumina/carbon-black particle size ratio. The pressure dependence of the resistivity increases as the composition approaches the percolation threshold. When the relative composition at the percolation threshold is fixed, the sensitivity increases with increasing matrix/dispersoid initial particle size ratio.No potential conflict of interest relevant to this article was reported.Acta Medica Okayama13691988Studies on the acid-base properties of the AIBr3-NaBr melts26062608ENHidetakaHayashiNHayashiZTakeharaAKatagiri<p>The acid-base properties of the ZnBr[2]-NaBr melts at 623 K were investigated on the basis of the electromotive force measurements of a zinc-zinc concentration cell. The following two chemical equilibria were postulated to describe the acid-base character of the melts ZBnr[2]+Br[-]=ZnBr[3][-] K[1] ZnBr[3][-]+Br[-] =ZnBr[4][2+] K[2] The equilibrium constants K[1] and K[2], were determined to be 5.0~10, and 1.0~10[2], respectively, at 623 K</p>No potential conflict of interest relevant to this article was reported.Acta Medica Okayama14021993Codeposition of a-alumina particles from acid copper sulfate bath362365ENHidetakaHayashiShin-yaIzumiIsaoTari<p>The purpose of this work is to elucidate the factors affecting the codeposition of a-alumina particles with copper from
an acid copper sulfate bath. The effect of current density and particle concentration in the bath on the amount of codeposited
a-alumina were determined. In order to evaluate the surface-chemical properties of the particles, the zeta-potential
of a-alumina particles in the plating bath was determined by means of the streaming potential method. The amounts of
adsorbed Cu 2+ and SO2( from the plating bath were also determined. The amount of codeposited a-alumina particles was
found to be greater than those reported in literature, in spite of the negative zeta-potential values of a-alumina. This
indicates that the electrostatic interaction between the particles and the cathode is not the essential factor of the codeposition
process. It is considered that the amount of adsorbed Cu 2+ on the a-alumina particle plays an important role in the
codeposition behavior.</p>
No potential conflict of interest relevant to this article was reported.Acta Medica Okayama14021993Studies on the acid-base properties of the ZnBr2NaBr molten salt system386389ENHidetakaHayashiKiyofumiUnoZen-ichiroTakeharaAkiraKatagiri<p>The acid-base properties of the ZnBr2-NaBr melts at 623 K were investigated on the basis of the electromotive force
measurements of a zinc-zinc concentration cell. The following two chemical equilibria were postulated to describe the
acid-base character of the melts.</p>No potential conflict of interest relevant to this article was reported.Elsevier Science LtdActa Medica Okayama0272-88423442008Improvement of piezoresistance properties of silicon carbide ceramics through co-doping of aluminum nitride and nitrogen845848ENAkiraKishimotoYasuyukiOkadaHidetakaHayashiThe piezoresistance coefficient was measured on co-doped silicon carbide ceramics. Evaluation samples of alpha-silicon carbide ceramics were first fabricated by glass capsule HIP method using powder mixture of silicon carbide and aluminum nitride with various ratios. The resultant aluminum nitride added silicon carbide ceramics were doped with nitrogen by changing the post-HIP nitrogen gas pressure. The lattice parameter increased with the amount of adding aluminum nitride indicating that the incorporated aluminum substituted smaller silicon atoms. After post-HIP treatment, lattice parameter then decreased with nitrogen gas pressure. The piezoresistive coefficient increased with the addition of aluminum nitride, it further increased with the nitrogen doping pressure.No potential conflict of interest relevant to this article was reported.