Papers by Author: Shin Ichi Hirano

Abstract: Blood Pond Hell (Chinoike Jigoku) is located in the hot spring town of Beppu, in Kyushu Island of Japan, and features a unique hot, acidic, red-coloured pond. This study aimed to investigate the microbial diversity in this unique extreme environment and eventually to isolate useful acidophilic microbes. The initial PCR (using bacteria-or archaea-specific primers) on environmental samples detected the presence of bacteria, but not archaea. The following random sequencing analysis confirmed the presence of a large bacterial diversity at the site (123 clones comprising 18 bacterial and 1 archaeal genera), including those closely related to known autotrophic and heterotrophic acidophiles (Acidithiobacillus sp., Sulfobacillus sp., Alicyclobacillus sp.). Nonetheless, successive enrichment cultivation with Fe (III) under oxygen depletion lead to isolation of previously non-detected archaeal (Sulfolobus sp.) colonies on solid media. Two isolates showing Fe (III) reduction ability were named Sulfolobus sp. GA1 and GA2. The isolates were also found to reduce highly toxic Cr (VI) to less toxic/soluble Cr (III), demonstrating their potential utility in metal bioremediation.

Abstract: The effect of poly ammonium acrylate (PAA-NH4) dispersant on the dispersibility of Pb(Zr,Ti)O3 (PZT) slurries and the piezoelectric properties of resultant PZT sintered bodies was investigated for the establishment of environmentally friendly aqueous processing. The dispersion state and viscosity of PAA-NH4-added PZT aqueous slurries strongly depended on the slurry pH. Well-dispersed PZT slurries with negligibly small Pb2+ dissolution were obtained in the alkaline side due to the electrostatic steric hindrance effect of adsorbed polyelectrolyte dispersant molecules with a high dissociation ratio of carboxylic acid groups. The homogeneous dense microstructure and the enhancement of the piezoelectric properties of PZT ceramic bodies were achieved by preparing the aqueous PZT slurry with an optimum amount of dispersant.

Abstract: The catalytic and electrical properties of an electrochemical NOx reduction system were investigated. A power above 3.5W/cm2 reduced more than 60% of NOx to N2 over the (La,Sr)CoO3-α/Ce0.9Gd0.1O1.95/Pt laminated system in a temperature range of 450°C to 650°C. O2- transportation removed the oxygen around the cathode layer through the Ce0.9Gd0.1O1.95 electrolyte layer, then NO was able to decompose to N2 at the cathode. This ceria-based system exhibited stable NOx reduction with respect to electrical power, regardless of operating temperature.