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78 巻, 4 号
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石山 新太郎, 馬場 祐治, 藤井 亮, 中村 勝, 今堀 良夫2014 年 78 巻 4 号 p. 137-141
発行日: 2014年
公開日: 2014/04/01
ジャーナル フリーTo prevent vaporization damage of BNCT (Boron Neutron Capture Therapy) lithium target during operation, direct synthesis of Li3N thin layer on lithium target surface was demonstrated in 0.1 MPa N2 gas at temperature below 548 K and the following conclusions were derived; (1) Synthesis of Li3N thin layer on lithium surface was confirmed after nitridation at 276~548 K with surface contamination by oxygen and carbon. (2) Rapid nitridation over 1~5 mass%/min was observed above Li melting temperature, whereas slow reaction under 0.02~0.5 mass%/min below melting temperature. (3) During nitridation, removal of oxygen contamination on Li3N thin layer is taken place by nitrogen below Li melting temperature.
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上田 哲也, 長尾 昌樹, 池尾 直子, 鷲尾 宏太, 木下 昭人, 加藤 晃, 向井 敏司2014 年 78 巻 4 号 p. 142-148
発行日: 2014年
公開日: 2014/04/01
ジャーナル フリーWeight reduction is effective for improving fuel efficiency of automobiles. Although magnesium is widely recognized as the lightest structural metal, applications for the automobile are limited because of the relatively low ductility, toughness, impact resistance and fatigue resistance. The aim of this research was to evaluate the impact energy absorption capability of a magnesium alloy pipe by a numerical simulation. First of all, finite element (FE) analysis of impact compression of magnesium alloy pipes was performed to design the shape of anvils for a dynamic compression experiment. The compression tests were conducted at a high strain rate on two Mg alloys, AZ31 and Mg-0.6Y, to examine the deformation response. The load-displacement data obtained were compared with the results of FE analysis to validate the simulation. The FE analysis revealed that the AZ31 pipe fractured at an early stage of deformation, while the Mg-0.6Y pipe fractured at about 90% compressed. As a result, Mg-0.6Y pipe exhibited lower yield strength, but a higher absorption energy capability than AZ31 pipe due to a weakened basal texture.
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釘屋 奈都子, 永田 和宏, 北田 正弘2014 年 78 巻 4 号 p. 149-158
発行日: 2014年
公開日: 2014/04/01
ジャーナル フリーThe manufacturing technique of steel chains used for four Japanese armatures from the end of Muromachi to the Edo period has been investigated. The chains used in Kusazuri (tasset) and two types of Kote (guntlet) were composed of steel rings in round and oval shapes while those used in Kusarikatabira (chainmail) was only round. As for the former ones, round rings were connected by oval rings. The diameter of steel wire of rings was about 1 mm. The steel wire was produced from steel plate with the carbon content of 0.11 to 0.40 mass%. Steel was forge-and-welded twice to make in plate and was cut in a bar. The steel bar was drawn into standardized wires by die with the draft percentage of about 25% and annealed. Drawing of standardized wire followed by annealing was repeated several times to make a wire for armatures. The crystal grains in wires were elongated in axial direction and the aspect ratio of grain in oval rings was larger than that in round rings. A wire was rolled around a stick and cut by chisel to make rings.
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坂本 広太, 小宮谷 真司, 高原 豊文, 住佐 太, 大津 直史2014 年 78 巻 4 号 p. 159-162
発行日: 2014年
公開日: 2014/04/01
ジャーナル フリーTo evaluate the antibacterial performance of photocatalytic coating, Japan Industrial Standard (JIS) committee has suggested the standard testing conditions for quantitative evaluation. However, these conditions had been constructed based on the experimental consideration from the coating formed on a glass substrate. In this study, to check the applicability of the JIS conditions to the coating on a titanium (Ti) substrate, the change of the survival rate of Escherichia coli (E. coli) on the Ti surface was evaluated. We confirmed that the decrease of microorganisms caused by dryness and UV-light were effectively suppressed by the use of these conditions. Furthermore, when testing the antibacterial performance of an anodic TiO2 layer on a Ti substrate, its performance could be evaluated clearly. In conclusion, we confirmed that the survival rate of E. coli on the Ti substrate could be evaluated by using the experimental conditions described in the JIS.
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大口 友里恵, 赤堀 俊和, 服部 友一, 福井 壽男, 新家 光雄2014 年 78 巻 4 号 p. 163-169
発行日: 2014年
公開日: 2014/04/01
ジャーナル フリーBeta-type Ti-29Nb-13Ta-4.6Zr(TNTZ), which is a recently developed biomedical titanium alloys, shows a relatively low Young's modulus of around 60 GPa when subjected to a solution treatment. However, our focus in this study was on the practical applications of TNTZ in vivo because its mechanical strength decreases with solution treatment progress. Therefore, we investigated the effect of fine particle bombarding process (FPB) on the mechanical properties of TNTZ subjected to a cold-swaging treatment in order to maintain its relatively low Young's modulus and to improve its mechanical properties. The relative bone contact ratios between the cancellous bones of Japanese white rabbits and column-shaped TNTZ samples subjected to FPB were also evaluated.
The microstructure of cold-swaged TNTZ showed a single beta-phase with a marble-like structure. Moreover, its Vickers hardness did not increase remarkably with changes in its diameter, although the average diameter of the beta-grains of solutionized TNTZ ranged from 5.0 to 20 μm, depending on the increase in the holding time of the solution treatment. The Vickers hardness and Young's modulus of TNTZ subjected to FPB increased at the edge of the specimen surface to be around 70% and 15%, respectively, more than those of cold-swaged TNTZ. Further, the fatigue strength of TNTZ subjected to FPB became significantly higher than that of cold-swaged TNTZ in the high-cycle fatigue life region. Lastly, TNTZ with a rough surface texture (Ra: 0.65 μm) showed a relative bone contact ratio of more than 80% after undergoing FPB; this value was significantly higher than that of cold-swaged TNTZ with a very smooth surface texture (Ra: 0.07 μm).
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倉科 佑太, 濱野 拓巳, 宮田 昌悟, 小茂鳥 潤, 小山 尹誉2014 年 78 巻 4 号 p. 170-176
発行日: 2014年
公開日: 2014/04/01
ジャーナル フリーIn this study, we investigated the growth response of chondrocytes on a metallic cell culture device with different microtopographies. Two different topographies were generated on 316L stainless steel by fine particle peening (FPP) treatment using either glass or alumina shot particles. Glass particles provided surface of micro asperities at low frequency spacing, whereas alumina provided surface micro asperities at high frequency spacing. Calf chondrocytes were seeded and cultured on both treated and smooth stainless steel surfaces. The cells were then counted. Based on the results, the FPP-treated surfaces showed better cell proliferation and denser filopodia compared to the polished surface, indicating that the micro asperities on the surface of the plate encouraged cell proliferation and adhesion. The number of cells observed on the FPP-treated surface depended on the shape of the asperities formed by FPP treatment, and alumina-treated surface had the highest cell counts. Cell distribution assay indicated that cells growing on the alumina-treated surface migrated easily. In addition, when the alumina-treated surface was used as a cell culture dish to incubate chondrocytes, cell proliferation was similar to that of obtained using polymeric culture dishes, demonstrating that FPP-treated surfaces are appropriate for use in cell culture dishes.
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