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2. AC Electromagnetic Field Controls the Biofilms on the Glass Surface by Escherichia coli & Staphylococcus epidermidis Inhibition Effect

Author

Aoyama, Natsu, primary, Kanematsu, Hideyuki, additional, Barry, Dana M., additional, Miura, Hidekazu, additional, Ogawa, Akiko, additional, Kogo, Takeshi, additional, Kawai, Risa, additional, Hagio, Takeshi, additional, Hirai, Nobumitsu, additional, Kato, Takehito, additional, Yoshitake, Michiko, additional, and Ichino, Ryoichi, additional

Published
2023
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11. Impedance Characteristics of Monolayer and Bilayer Graphene Films with Biofilm Formation and Growth

Author

Nakagawa, Ryoichi, primary, Saito, Kai, additional, Kanematsu, Hideyuki, additional, Miura, Hidekazu, additional, Ishihara, Masatou, additional, Barry, Dana M., additional, Kogo, Takeshi, additional, Ogawa, Akiko, additional, Hirai, Nobumitsu, additional, Hagio, Takeshi, additional, Ichino, Ryoichi, additional, Ban, Masahito, additional, Yoshitake, Michiko, additional, and Zimmermann, Stefan, additional

Published
2022
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15. Detection of Biofilm Formation on Material Surfaces by Ag + Coating.

Author

Kogo, Takeshi, Sugi, Kazufumi, Kanematsu, Hideyuki, Kai, Hotaka, Ogawa, Akiko, Hirai, Nobumitsu, Takahashi, Toshiyuki, and Kato, Takehito

Subjects
GENTIAN violet, SURFACES (Technology), ALKALI metal ions, BIOFILMS, IRON ions
Abstract

The evaluation of biofilm formation is important, given the ubiquity and problematic nature of biofilms in industrial and medical settings, as well as in everyday life. Basically, biofilms are formed on substrates. Therefore, it is essential to consider the properties of the substrates during biofilm evaluation. The common dye staining method to evaluate biofilm formation requires a short evaluation time and enables the evaluation of a large area of the sample. Furthermore, it can be easily determined visually, and quantitative evaluation is possible by quantifying color adsorption. Meanwhile, the dye staining method has the problem of adsorption even on substrate surfaces where no biofilm has formed. Therefore, in this study, we focused on Ag+ reduction reaction to devise a novel biofilm evaluation method. Ag+ is highly reductive and selectively reacts with organic substances, such as saccharides, aldehydes, and proteins contained in biofilms, depositing as metallic Ag. First, to simply evaluate biofilm formation, we used a glass substrate as a smooth, transparent, and versatile oxide material. We observed that the amount of Ag deposited on the substrate was increased proportionally to the amount of biofilm formed under light irradiation. Upon comparing the Ag deposition behavior and adsorption behavior of crystal violet, we discovered that for short immersion times in AgNO3 solution, Ag deposition was insufficient to evaluate the amount of biofilm formation. This result suggests that the Ag reduction reaction is more insensitive than the crystal violet adsorption behavior. The results of the Ag deposition reaction for 24 h showed a similar trend to the crystal violet dye adsorption behavior. However, quantitative biofilm evaluation using the proposed method was difficult because of the Ag+ exchange with the alkali metal ions contained in the glass substrate. We addressed this issue by using the basic solution obtained by adding an ammonia solution to aqueous AgNO3. This can cause Ag+ to selectively react with the biofilm, thus enabling a more accurate quantitative evaluation. The optimum was determined at a ratio of distilled water to aqueous ammonia solution of 97:3 by weight. This biofilm was also evaluated for materials other than ceramics (glass substrate): organic material (polyethylene) and metal material (pure iron). In the case of polyethylene, a suitable response and evaluation of biofilm formation was successfully achieved using this method. Meanwhile, in the case of pure iron, a significantly large lumpy deposit of Ag was observed. The likely reason is that Ag precipitation occurred along with the elution of iron ions because of the difference in ionization tendency. It could be concluded that the detection of biofilm formation using this method was effective to evaluate biofilm formation on materials, in which the reduction reaction of [Ag(NH3)2]+ does not occur. Thus, a simple and relatively quantitative evaluation of biofilms formed on substrates is possible using this method. [ABSTRACT FROM AUTHOR]

Published
2022
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25. Biofilm Formation of a Polymer Brush Coating with Ionic Liquids Compared to a Polymer Brush Coating with a Non-Ionic Liquid

Author

Kanematsu, Hideyuki, primary, Oizumi, Atsuya, additional, Sato, Takaya, additional, Kamijo, Toshio, additional, Honma, Saika, additional, Barry, Dana, additional, Hirai, Nobumitsu, additional, Ogawa, Akiko, additional, Kogo, Takeshi, additional, Kuroda, Daisuke, additional, Sano, Katsuhiko, additional, Tsunashima, Katsuhiko, additional, Lee, Seung-Hyo, additional, and Lee, Myeong-Hoon, additional

Published
2018
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28. 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

29. 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

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