American Chemical Society (ACS) Acta Medica Okayama 1932-7447 127 5 2023 Uniform Formation of a Characteristic Nanocomposite Structure of Biogenous Iron Oxide for High Rate Performance as the Anode of Lithium-Ion Batteries 2223 2230 EN Masakuni Takahashi Graduate School of Natural Science and Technology, Okayama University Ryo Sakuma Graduate School of Natural Science and Technology, Okayama University Hideki Hashimoto Graduate School of Natural Science and Technology, Okayama University Tatsuo Fujii Graduate School of Natural Science and Technology, Okayama University Jun Takada Graduate School of Natural Science and Technology, Okayama University Recently, Fe2O3 has been considered as an alternative anode material for lithium-ion batteries (LIBs) owing to its high theoretical capacity (approximately 1000 mA h g-1), low cost, and nontoxicity. However, its rate performance remains poor relative to that of the conventional graphite anode. In this study, Fe2O3-based anodes were prepared through the annealing of biogenous Fe2O3 (L-BIOX) samples produced by an aquatic Fe-oxidizing bacterium. The effect of the annealing temperature on the performance of the synthesized Fe2O3-based material as the anode of an LIB was investigated. Electrochemical measurements revealed that the annealed L-BIOX samples at 300-700 degrees C exhibited higher rate performances than the unannealed material. Particularly, the sample annealed at 700 degrees C exhibited the highest capacity among the synthesized materials and showed a higher performance than the previously reported Fe2O3-based anodes. It exhibited a capacity of 923 mA h g-1 even at a high current density of 2 A g-1. After annealing at 700 degrees C and discharging, the synthesized biogenous material had a uniform nanocomposite structure composed of alpha-Fe2O3 nanoparticles dispersed in an amorphous matrix of Li-Si-P oxide. To form this uniform nanostructure, the solid-state diffusion resistance of the Li+ ions in the active material was reduced, which consequently improved the rate performance of the electrode. Therefore, this study provides substantial insights into the development and improvement of the performance of novel Fe2O3-based nanomaterials as the anode of LIBs. No potential conflict of interest relevant to this article was reported.

American Chemical Society Acta Medica Okayama 2470-1343 7 15 2022 Eco-Benign Orange-Hued Pigment Derived from Aluminum-Enriched Biogenous Iron Oxide Sheaths 12795 12802 EN Katsunori Tamura Graduate School of Natural Science and Technology, Okayama University Yuri Oshima Graduate School of Natural Science and Technology, Okayama University Yuta Fuse Graduate School of Natural Science and Technology, Okayama University Noriyuki Nagaoka Advanced Research Center for Oral and Craniofacial Sciences, Okayama University Tatsuki Kunoh Graduate School of Natural Science and Technology, Okayama University Makoto Nakanishi Graduate School of Natural Science and Technology, Okayama University Tatsuo Fujii Graduate School of Natural Science and Technology, Okayama University Tokuro Nanba Graduate School of Environmental and Life Science, Okayama University Jun Takada Graduate School of Natural Science and Technology, Okayama University Inorganic pigments have been widely used due to their low cost of production, strong hiding power, and chemical resistance; nevertheless, they have limited hue width and chromaticity. To eliminate these disadvantages, we herein propose the use of an ingenious biotemplate technique to produce Al-enriched biogenic iron oxide (BIOX) materials. Spectrophotometric color analysis showed that high levels of Al inclusion on heat-treated BIOX samples produced heightened yellowish hues and lightness. The Al-enriched BIOX sheaths exhibited a stable tubular structure and excellent thermal stability of color tones after heating at high temperatures and repetitive heat treatments. Ultrastructural analysis and mechanical destruction experiments revealed that the highly chromatic orange-hue of these pigments are ascribed probably to an ingenious cylindrical nanocomposite architecture composed of putative Fe-included low crystalline Al oxide regions and hematite particles embedded therein. The present work therefore demonstrates that the bioengineered material can serve as an epochal orange-hued inorganic pigment with low toxicity and marked thermostability that should meet large industrial demand. No potential conflict of interest relevant to this article was reported.

American Chemical Society Acta Medica Okayama 2470-1343 5 42 2020 Preparation and Characterization of Additional Metallic Element-Containing Tubular Iron Oxides of Bacterial Origin 27287 27294 EN Katsunori Tamura Graduate School of Natural Science and Technology, Okayama University Tatsuki Kunoh Graduate School of Natural Science and Technology, Okayama University Makoto Nakanishi Graduate School of Natural Science and Technology, Okayama University Yoshihiro Kusano Department of Applied Chemistry and Biotechnology, Okayama University of Science Jun Takada Graduate School of Natural Science and Technology, Okayama University Biogenic microtubular iron oxides (BIOXs) derived from Leptothrix spp. are known as promising multifunctional materials for industrial applications such as ceramic pigments and catalyst carriers. Here, we report unprecedented BIOX products with additive depositions of various metallic elements prepared by a newly devised "two-step" method using an artificial culture system of Leptothrix cholodnii strain OUMS1; the method comprises a biotic formation of immature organic sheaths and subsequent abiotic deposition of Fe and intended elements on the sheaths. Chemical composition ratios of the additional elements Al, Zr, and Ti in the respective BIOXs were arbitrarily controllable depending on initial concentrations of metallic salts added to reaction solutions. Raman spectroscopy exemplified an existence of Fe-O-Al linkage in the Al-containing BIOX matrices. Time-course analyses revealed the underlying physiological mechanism for the BIOX formation. These results indicate that our advanced method can contribute greatly to creations of innovative bioderived materials with improved functionalities. No potential conflict of interest relevant to this article was reported.

Springer Japan Acta Medica Okayama 1431-0651 15 3 2011 Characterization of an OmpA-like outer membrane protein of the acidophilic iron-oxidizing bacterium, Acidithiobacillus ferrooxidans 403 410 EN Mohammed Abul Manchur Mei Kikumoto Tadayoshi Kanao Jun Takada Kazuo Kamimura An OmpA family protein (FopA) previously reported as one of the major outer membrane proteins of an acidophilic iron-oxidizing bacterium Acidithiobacillus ferrooxidans was characterized with emphasis on the modification by heat and the interaction with peptidoglycan. A 30-kDa band corresponding to the FopA protein was detected in outer membrane proteins extracted at 75A degrees C or heated to 100A degrees C for 10 min prior to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). However, the band was not detected in outer membrane proteins extracted at a parts per thousand currency sign40A degrees C and without boiling prior to electrophoresis. By Western blot analysis using the polyclonal antibody against the recombinant FopA, FopA was detected as bands with apparent molecular masses of 30 and 90 kDa, suggesting that FopA existed as an oligomeric form in the outer membrane of A. ferrooxidans. Although the fopA gene with a sequence encoding the signal peptide was successfully expressed in the outer membrane of Escherichia coli, the recombinant FopA existed as a monomer in the outer membrane of E. coli. FopA was detected in peptidoglycan-associated proteins from A. ferrooxidans. The recombinant FopA also showed the peptidoglycan-binding activity. No potential conflict of interest relevant to this article was reported.

Faculty of Engineering, Okayama University Acta Medica Okayama 0475-0071 25 1 1990 Preparation of ZnO Films by Activated Reactive Evaporation Method 23 35 EN Yoshinari Miura Jun Takada Akiyoshi Osaka Toshio Kawamura 10.18926/15486 Zinc oxide films were prepared on silica glass substrates by the use of an r.f. activated reactive evaporation (ARE) method, and were examined by X-ray diffraction (XRD) and scanning electron micrograph (SEM). XRD measurements indicate that the films were c-axis oriented and that an r.f. plasma of Zn and O was necessary for the ZnO film deposition. Substrate temperature, oxygen gas pressure, evaporation rate, r.f. power and inlet position of oxygen gas effect the c-axis orientation, the growth rate and the microstructure of the films. Optimum conditions for a dense film with a fine texture of the surface and having good crystallinity were as follows: the substrate temperature;400℃, the evaporation rate;5.0(A)/s, the oxygen pressure;2.0x10(-4) Torr, the r.f. power;150 to 200W, and the oxygen gas inlet near the substrate. For the film prepared under the optimum conditions, the standard deviation　σ　of the rocking curve for the (002) diffraction was 1.9deg, smaller than that of the film prepared by using an r.f. sputtering method. No potential conflict of interest relevant to this article was reported.

Faculty of Engineering, Okayama University Acta Medica Okayama 0475-0071 24 1 1989 The Diffusion of Sodium Ions into Tin Oxide Thin Films from Glass Substrates 53 61 EN Akiyoshi Osaka Kiichi Oda Jun Takada Yoshinari Miura 10.18926/15474 Electrical resistance and X-ray photoelectron depth profile analysis are studied for antimony doped tin oxide films developed on silica, alkali-free and sodalime slide glass substrates. The sodium ions diffused from the substrates to the films prevented the crystal growth of rutile type tin oxide in the film, resulting in the high electrical resistance. A diffusion layer has been detected for each film with diffuse profiles of multi valent cations (Sn, Si or Ca) at the interface of the tin oxide film and substrate. A greater amount of sodium atoms have been detected in the film developed on the soda-lime glass while almost no sodium atoms have been found in those on the other substrates. This can be explained by the diffusion of the sodium ions in the substrate due to a drastic hydronium-sodium exchange mechanism under highly acidic conditions during the dipping and drying processes. No potential conflict of interest relevant to this article was reported.

Faculty of Engineering, Okayama University Acta Medica Okayama 0475-0071 26 2 1992 Preparation of Mullite Dispersed Silica Ceramics through Sol-Gel Processing 61 67 EN Akiyoshi Osaka Tokuro Nanba Jun Takada Yoshinari Miura 10.18926/15473 Mullite-dispersed silica ceramics were prepared through sol-gel processing by the use of tetraethoxy silane, aluminium nitrate and aluminium isopropoxide as the Si and Al sources where HCl and HN0(3) were the catalyst. Effect of the starting materials, solvents and catalysts was examined on the gelation time or temperature of mullite precipitation. Apparent activation energy of gelation ranged from 80 to 95kJ/mol. The presence of AI in the sols elongated the gelling time suggesting the formation of chelate bonds between AI and Si-OR or Si-OH bonds. No potential conflict of interest relevant to this article was reported.

Faculty of Engineering, Okayama University Acta Medica Okayama 0475-0071 26 2 1992 Preparation and Characterization of Ti(2)O(3) Films Deposited on Sapphire Substrate by Activated Reactive Evaporation Method 69 75 EN Tatsuo Fujii Tokuro Nanba Akiyoshi Osaka Yoshinari Miura Jun Takada 10.18926/15436 (001)-oriented Ti(2)O(3) films were epitaxially grown on a(001)-face of sapphire single-crystalline substrate by an activated reactive evaporation method. The formation ranges of stoichiometric and nonstoichiometric Ti(2)O(3) films were determined as a function of the substrate temperature (Ts), the oxygen pressure (Po(2)) and the deposition rate. Stoichiometric Ti(2)O(3) films were grown at Ts≧673K under Po(2)≧1.0×10(-4)Torr, which showed the metal-insulator transition with a sharp change in electrical resistivity from 3.5×10(-2) to 2.6×10(-3)Ωcm at 361K. Nonstoichiometric films prepared under less oxidized conditions did not exhibit the transition. The nonstoichiometry of the Ti(2)O(3)films was discussed in terms of excess Ti ions. No potential conflict of interest relevant to this article was reported.

Faculty of Engineering, Okayama University Acta Medica Okayama 0475-0071 41 1 2007 Structure, Morphology and Color Tone Properties of theNeodymium Substituted Hematite 93 98 EN Makoto Nakanishi Tatsuo Fujii Jun Takada 10.18926/14088 Co-precipitation method has been employed to fabricate neodymium substituted hematite with different compositions from the aqueous solution of their corresponding metal salts. Thermal analysis and X-ray diffraction studies revealed the coexistence of Fe(2)O(3) and Nd(2)O(3) phases up to 1050℃ and formation of solid solution phase among them at 1100℃ and above temperatures, which was evidenced by shifting of the XRD peaks. Unit cell parameters and the cell volumes of the samples were found to increase by adding Nd(3+) ions in the reaction process. FESEM studies showed the suppression of particle growth due to the presence of Nd(3+) ions. Spectroscopic measurement evidenced that neodymium substituted hematite exhibited brighter yellowish red color tone than that of pure α-Fe(2)O(3). No potential conflict of interest relevant to this article was reported.

岡山大学環境理工学部 Acta Medica Okayama 1341-9099 2 1 1997 活性化反応蒸着法によるZnO系透明導電膜の作製と物性 121 129 EN Takashi Fujiwara Tatsuo Fujii Tokuro Nanba Jun Takada Yoshinari Miura 10.18926/fest/11614 Zinc oxide films were prepared on silica glass substrates by the use of an r.f. activated reactive evaporation (ARE) method, and were examined by X-ray diffraction (XRD) and scanning electron microscope (SEM). The electrical conductivity of the films and the doping effect of Al ions were also investigated. XRD measurements indicate that the films were c-axis oriented and that an r.f. plasma of Zn and O was necessary for the ZnO film deposition. Substrate temperature, oxygen gas pressure, evaporation rate, r.f. power and Al doping amount affect the c-axis orientation, the growth rate, the microstructure of the films and electrical conductivity. Optimum conditions with a fine texture of the surface and having good ctystallinity as well as good conductivity (≒10(-4)Ω・cm) were as follows : the substrate temperature; 200℃, the total evaporation rate; 1.0Å/s, the oxygen pressure; 2.0×10(-4) Torr, the r.f. power; 250W and the Al evaporation rare ratio; 2～6%. The films with 1.0×10(-3)Ω・cm were prepared at 50℃ for the substrate temperature. No potential conflict of interest relevant to this article was reported.