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Kubuki S.,Tokyo Metroplitan University | Iwanuma J.,Tokyo Metroplitan University | Akiyama K.,Tokyo Metroplitan University | Mikuni A.,Yamaguchi Prefectural Industrial Technology Institute | Nishida T.,Kinki University
Hyperfine Interactions | Year: 2012

In order to enhance the mechanical strength of Hagi Porcelain (Hagiyaki), one of the oldest and famous potteries in Japan, new preparation condition was examined. Tempered Hagi porcelain, denominated as 'Hagi Porcelain B', was prepared with the Porcelain clay originating from Daido district, Yamaguchi Prefecture, Japan. Structural change of 'Hagi Porcelain B' was investigated by means of 57Fe-Mössbauer spectroscopy, X-ray diffractometry (XRD) and three-point bending test. Mechanical strength of the 'original Hagi Porcelain B' was estimated to be 43.1 MPa by means of the three-point bending test, while much larger value of 104.5 MPa could be achieved when tempered by a chemical modification. Mössbauer spectrum of the 'original Hagi porcelain B' was composed of a paramagnetic doublet and a magnetic sextet due to Fe(III) of γ-Fe 2O 3(maghemite), while only one paramagnetic doublet due to to octahedral Fe(II)O 6 was observed for the 'tempered Hagi Porcelain B' with isomer shift and quadrupole splitting values of 1.13 and 2.15 mm s -1, respectively. It is considered that the absence of magnetic phase causes an increase of the mechanical strength because the maghemite phase has a defect spinel structure. These results indicate that mechanical strength of the 'Hagi porcelain B' could be enhanced by controlling the sintering condition. © 2012 Springer Science+Business Media B.V.


Yamaguchi Y.,Tokyo University of Science | Emoto Y.,Tokyo University of Science, Yamaguchi | Kineri T.,Tokyo University of Science, Yamaguchi | Fujimoto M.,Yamaguchi Prefectural Industrial Technology Institute | And 3 more authors.
Journal of the Australian Ceramic Society | Year: 2012

A well-known gasochromic material is Pt-particle-dispersed tungsten trioxide (Pt/WO 3). Its optical properties could make it effective as a hydrogen-gas sensor. In this study, Pt-nanoparticle-dispersed WO 3 thin films were prepared using the sol-gel process, and their optical and electrical properties dependent on the working environment (i.e., temperature, hydrogen gas concentration, oxygen partial pressure, etc.) were investigated. The Pt/WO 3 thin films prepared at 400°C showed the largest change in optical transmittance and electrical conductivity when exposed to hydrogen gas compared with the films prepared at other temperatures. The optical absorbance and electrical conductivity were found to be dependent on the hydrogen and oxygen gas concentration in the atmosphere because generation and disappearance of W 5+ in the thin films depend on the equilibrium reaction between injection and rejection of H+ into and from the thin films. In addition, the equilibrium reaction is depends on the hydrogen and oxygen gas concentrations.


Yamaguchi Y.,Tokyo University of Science | Kineri T.,Tokyo University of Science, Yamaguchi | Fujimoto M.,Yamaguchi Prefectural Industrial Technology Institute | Mae H.,Yamaguchi Prefectural Industrial Technology Institute | And 2 more authors.
Key Engineering Materials | Year: 2011

Platinum (Pt)nanoparticle-dispersed tungsten trioxide (WO3) thin film is a gasochromic material that changes color from transparent to blue in an H2 gas atmosphere. The electrical conductivity of Pt-nanoparticle-dispersed WO3 is dependent on inserted protons and electrons, though the material is insulator in air, because these electrons and protons work as electrical carriers in WO3. In this study, Pt-nanoparticle-dispersed WO3 thin films were prepared using the sol-gel process, and the optical and electrical properties were evaluated in an atmosphere with or without H2 gas. Pt/WO3 thin films prepared at 400°C showed the largest change in electrical conductivity when exposed to 1% H2 gas compared with thin films prepared at other temperatures. The electrical conductivity of the film was dependent on an H 2 gas concentration in the range from 100 ppm to 1%. Pt/WO 3 thin films prepared by the sol-gel process are expected to be used for H2 gas sensor devices due to the linear relationship between the electrical conductivity and H2 gas concentration. © (2011) Trans Tech Publications, Switzerland.


Yamaguchi Y.,Tokyo University of Science | Emoto Y.,Tokyo University of Science, Yamaguchi | Kineri T.,Tokyo University of Science, Yamaguchi | Fujimoto M.,Yamaguchi Prefectural Industrial Technology Institute | And 3 more authors.
Ionics | Year: 2012

A well-known gasochromic material is Pt particle-dispersed tungsten trioxide (Pt/WO 3). Its optical properties could make it effective as a hydrogen gas sensor. In this study, Pt nanoparticle-dispersed WO 3 thin films were prepared using the sol-gel process, and their optical and electrical properties dependent on the working environment (i. e., temperature, hydrogen gas concentration, oxygen partial pressure, etc.) were investigated. The Pt/WO 3 thin films prepared at 400 °C showed the largest change in optical transmittance and electrical conductivity when exposed to hydrogen gas compared with the films prepared at other temperatures. The optical absorbance and electrical conductivity were found to be dependent on the hydrogen and oxygen gas concentration in the atmosphere because generation and disappearance of W 5+ in the thin films depend on the equilibrium reaction between injection and rejection of H + into and from the thin films. In addition, the equilibrium reaction depends on the hydrogen and oxygen gas concentrations. © 2012 Springer-Verlag.


Imada K.,Yamaguchi University | Tanaka S.,Yamaguchi University | Ibaraki Y.,Yamaguchi University | Yoshimura K.,Yamaguchi Prefectural Industrial Technology Institute | Ito S.,Yamaguchi University
Letters in Applied Microbiology | Year: 2014

There is very little information on the fungistatic or fungicidal effect of visible light. This study investigated the effect of 405-nm light, generated by a light-emitting diode array, on the economically important fungus Botrytis cinerea. The mycelial growth of B. cinerea was inhibited to the greatest extent by light at 405 and 415 nm and was negligibly inactivated at 450 nm, suggesting the presence of a photosensitizing compound that absorbs light mainly at wavelengths of 405-415 nm. Delta-aminolevulinic acid, a precursor of endogenous photosensitizer porphyrins, was used to determine the role of these porphyrins in 405-nm light-mediated photoinactivation of the fungus. Concentration-dependent inhibition of spore germination by delta-aminolevulinic acid and accumulation of singlet oxygen in the spores was observed when the spores were exposed to 405-nm light. These results suggest that the excitation of endogenous porphyrins and subsequent accumulation of singlet oxygen could partially explain the 405-nm light-mediated photoinactivation of B. cinerea. The development of symptoms in detached tomato leaves inoculated with B. cinerea spores was significantly reduced by irradiation with 405-nm light, indicating that 405-nm light has a potential use for controlling plant diseases caused by B. cinerea. © 2014 The Society for Applied Microbiology.


Kamimura A.,Yamaguchi University | Yamamoto S.,Yamaguchi University | Yamada K.,Yamaguchi University | Yamada K.,Yamaguchi Prefectural Industrial Technology Institute
ChemSusChem | Year: 2011

Waste fiber-reinforced plastics (FRP) and unsaturated polyesters were readily depolymerized by subjecting them to a treatment with ionic liquids under heating conditions. The use of microwaves for heating effectively progressed depolymerization, whereas the conventional heating method was ineffective for this purpose. We isolated the monomeric material, phthalic anhydride, by direct distillation from the reaction pot under reduced pressure with yields of more than 90 %. We recovered the glass fibers in a pure form and achieved the effective removal of polystyrene, the linker unit of FRP. Ionic liquids were useful for several iterations of the reaction, and purification of the used ionic liquids was also possible. Thus, we developed a new use of ionic liquids for chemical recycling of waste plastics. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Kamimura A.,Yamaguchi University | Akinari Y.,Yamaguchi University | Watanabe T.,Yamaguchi University | Yamada K.,Yamaguchi Prefectural Industrial Technology Institute | Tomonaga F.,Yamaguchi Prefectural Industrial Technology Institute
Journal of Material Cycles and Waste Management | Year: 2010

We have achieved major improvements in the efficient chemical recycling of waste fiber-reinforced plastics (FRPs). The effects of reduction in the amounts of dimethylaminopyridine (DMAP) used for depolymerization were examined. The treatment of waste FRP in the presence of 1 or 2 wt% DMAP resulted in the successful recovery of monomeric materials that could be employed in the polymerization process to produce recycled plastic. The separation of linker units from glass fiber, however, was unsuccessful. The purity of the recovered monomeric material, when treated with activated charcoal, was improved to about 70%. This resulted in effective decoloration of the recovered monomer. Finally, the purified material, after undergoing repolymerization, provided high-quality recycled plastic comparable to new plastics produced from new monomers. © 2010 Springer Japan.


Yamada K.,Yamaguchi University | Yamada K.,Yamaguchi Prefectural Industrial Technology Institute | Tomonaga F.,Yamaguchi Prefectural Industrial Technology Institute | Kamimura A.,Yamaguchi University
Journal of Material Cycles and Waste Management | Year: 2010

We examined an improved preparation method of recycled unsaturated polyester resin from recovered monomeric materials obtained from the depolymerization of fiber-reinforced plastics (FRPs). The formation of unsaturated polyester progressed smoothly in the presence of catalytic amounts of Ca(OAc)2 and Ti(OBu)4. The quality of the resin was estimated by the durometer hardness test. The strength test of FRP board prepared from recycled resin showed sufficient hardness for practical use (about 94% of the tensile strength of new resin). We examined the recycled resin by using it to mold successfully an actual test product. © 2010 Springer Japan.


Nakazono M.,Yamaguchi University | Yoshiura A.,Yamaguchi University | Mizunuma M.,Yamaguchi Prefectural Industrial Technology Institute | Koganei M.,Yamaguchi University
Journal of Environmental Engineering | Year: 2012

Heat insulation specifications of the fitting which combined a Taiko-shoji with wooden pair glass sash are effective as the way of repairing a traditional wooden house with not only heat insulation performance but also the execution and design as well. In this paper, the insulation performance of Taiko-shoji was examined by indoor experiment, actual house measurement and numerical calculation. The results are as follows. As the result of indoor experiment, the heat resistance value of Taiko-shoji (air space=26mm) was at 1.3 times of single shoji and about 20% of the heat transfer coefficients decreased. As the result of measurement of improved actual house, the average heat resistance value of Taiko-shoji + pair glass was 0.64 m 3 K/W, pair glass only was 0.35 m 3 K/W. The overall heat transfer coefficient of Taiko-shoji + pair glass decreased to 27% of single glass by the numerical calculation. In case that the traditional house with single glass is repaired by Taiko-shoji + pair glass fitting, the validity of these specifications is shown by the simulations.


Yamada S.,Yamaguchi Prefectural Industrial Technology Institute | Tamura T.,Yamaguchi Prefectural Industrial Technology Institute | Mochizuki S.,Yamaguchi University
ICOPE 2015 - International Conference on Power Engineering | Year: 2015

Effect of Reynolds number on the torque and power characteristics of a small straight-bladed vertical axis wind turbine has been investigated experimentally under various wind velocity. The maximum mean torque coefficient and the maximum mean power coefficient increase with increasing Reynolds number based on wind velocity and representative length of wind turbine. The tip speed ratio for the maximum mean torque coefficient is almost independent of Reynolds number. Otherwise, the tip speed ratio for the maximum power coefficient increased as increasing Reynolds number. When the curvature parameter and the solidity represented forms of the wind turbine are same, the wind turbine performance can be successfully explained by the simple analytical functions, namely, the mean torque and the mean power coefficients can be represented well by the logarithmic functions of Reynolds number and quadratic or cubic function of the tip speed ratio. The proposed approximate equations successfully predict the experimental data for the particularly higher tip speed ratio.

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