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187 results on '"Hirai, Nobumitsu"'

56. Biofilm Formation Behaviors on Graphene byE. coliandS. epidermidis

Author

Kanematsu, Hideyuki, primary, Sato, M, additional, Shindo, Kodai, additional, Barry, Dana M., additional, Hirai, Nobumitsu, additional, Ogawa, Akiko, additional, Kogo, Takeshi, additional, Utsumi, Yuichi, additional, Yamaguchi, Akinobu, additional, Ikegai, Hajime, additional, and Mizunoe, Yoshimitsu, additional

Published
2017
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58. Fabrication of Porous Solidified Materials from Blast Furnace Slag Using Hydrothermal Hot-pressing Method and Measurement of Thermal Conductivity of Solidified Materials

Author

Hirai, Nobumitsu, Maeda, Soichiro, Katsuyama, Shigeru, and Tanaka, Toshihiro

Subjects
value-added materials, blast furnace slag, hydrothermal, porosity, thermal conductivity
Abstract

To produce insulating construction materials using hydrothermal reaction from blast furnace slag (BF slag) such as air-cooled, air granulated, and water-cooled slags, we investigated the fabrication of porous solidified materials from BF slag by a hydrothermal hot-pressing method. The thermal conductivity of the solidified materials was also investigated. The experimental conditions were; hydrothermal holding time from 0 to 120 min, hydrothermal temperature from 250 to 350°C, hydrothermal pressure from 20 to 80 MPa, and slag powder sizes less than 15 μm, 39±24 μm, 84±21 μm, 178±72 μm, 375±125 μm and more than 500 μm. It was found that growth of the hydrothermally reacted phase led to a higher density and higher thermal conductivity of the solidified materials. It was noteworthy that the thermal conductivity of the hydrothermal solidified materials became smaller when the size of the slag powder was larger. This was because the more porous structure introduced into the solidified materials resulted in a lower density of the solidified materials. It was also found that glassy slag such as water-cooled and air granulated slags can be solidified even if the size of the slag powder was more than 500 μm.

Published
2009

61. Microscopic Structure and Discharging Properties of Mechanically-Milled Positive Active Material PbO2 with an Addition of Sb in Lead-Acid Battery

Author

Tanaka Toshihiro, Rin Reimei, Katsuyama Shigeru, and Hirai Nobumitsu

Subjects
Battery (electricity), Materials science, Mechanical Engineering, Metals and Alloys, Analytical chemistry, Electron microprobe, Redox, Industrial and Manufacturing Engineering, law.invention, Magazine, law, Electrode, Materials Chemistry, Cyclic voltammetry, Capacity loss, Lead–acid battery
Abstract

PbO2 powder, which is active positive-electrode material in the lead-acid battery, was mechanically milled with Sb2O3 powder. It is well known that Sb contained in the grid of the lead-acid battery is useful for the protection of the premature capacity loss. The results of the X-ray diffraction and EPMA (Electron Probe Micro Analyzer) showed that the alloying between PbO2 and Sb2O3 proceeded during the milling process. The position of the reduction peak in the CV (Cyclic Voltammetry) curve shifted to the lower potential and the intensity of the reduction peak increased with an increase of the scanning speed of the potential. The intensity of the reduction peak in the CV curve for the electrode constructed from PbO2 powder added with Sb2O3 was much reduced compared to that for the electrode constructed from PbO2 powder. The result of EPMA showed that the reduction reaction from PbO2 to PbSO4 proceeded more rapidly in the electrode constructed from PbO2 powder added with Sb2O3, and that Sb was not detected in PbSO4 particles. The above phenomena observed in the electrode constructed from PbO2 powder added with Sb2O3 seem to be concerned with the protection of the premature capacity loss of the lead-acid battery.

Published
2007

70. Biofilm Formation Behaviors on Graphene by E. coli and S. epidermidis

Author

Kanematsu, Hideyuki, Sato, M, Shindo, Kodai, Barry, Dana M., Hirai, Nobumitsu, Ogawa, Akiko, Kogo, Takeshi, Utsumi, Yuichi, Yamaguchi, Akinobu, Ikegai, Hajime, and Mizunoe, Yoshimitsu

Abstract

The formation of biofilm on graphene materials was investigated in this study. Two kinds of laboratory biofilm reactors were used to produce biofilms artificially on glass specimens (on the laboratory scale). One of them was a loop-type and the biofilms were measured by Raman spectroscopy. The other one was the static immersion test in a culture containing bacteria. The biofilm formation was evaluated by using crystal violet. We expected that the graphene would have a strong resistance against biofilm formation. However, on the contrary, graphene tended to become more sensitive to biofilm formation when the portion of graphene increased. When we come to think about the future application for graphene, it should not be used for biomaterials, but as sensor for infectious diseases.

Published
2017

88. In Situ EC-AFM Observation on Pb Electrodes in Sulfuric Acid Solution with or without Lignin.

Author

Tabayashi, Daiji, Hirai, Nobumitsu, Shiota, Masashi, and Tamaka, Toshihiro

Subjects
*ELECTROLYTIC oxidation, *ATOMIC force microscopy, *VOLTAMMETRY, *LEAD, *SULFURIC acid, *LIGNINS, *ELECTROCHEMICAL analysis
Abstract

Surface morphologies of Pb electrodes in sulfuric acid solution with or without lignin at -20°C during anodic oxidation have been investigated by using in situ EC-AFM combined with cyclic voltammetry (CV). Whether the lignin is added or not in the solution, it was found at -20°C that the precipitation of lead sulfate crystals occurs immediately after supersaturation of dissolved Pb2+ ions at the anodic oxidation peak on CV. It was also found that the number of lead sulfate crystals formed on the Pb electrode after anodic oxidation decreases and the crystal size becomes larger when the lignin is added in the solution. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2003
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