著者

翠川 裕 仲井 正昭 翠川 薫 新家 光雄

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.80, no.3, pp.165-170, 2016 (Released:2016-02-25)

参考文献数

10

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A novel method for detecting antimicrobial activity using an innate property of the Salmonella bacteria, namely, the ability of Salmonella to produce hydrogen sulfide (H2S) was developed in this study. The effectiveness of the method was evaluated by comparing the antibacterial activity of copper to that of aluminum. Salmonella was inoculated over the entire surface of deoxycholate hydrogen sulfide lactose (DHL) agar plates that included Ammonium ferric citrate (C6H8FeN). Approximately 25 μL of cupric chloride (CuCl2, 1% weight ratio) solution or aluminum chloride (AlCl3, 1% weight ratio) solution was added to the center of the medium. The surface of the medium was covered with plastic PET (polyethylene terephthalate) material to induce an anaerobic state. Salmonella was cultured under anaerobic conditions at 310 K (37℃) for 86.4 ks (24 h). The antibacterial activity of copper was determined by observing the medium surface color change due to iron sulfide (FeS) formation, which was caused by the production of H2S by Salmonella; blackness indicated presence of newly formed FeS. A quantitative evaluation of copper's antimicrobial activity was performed using a gradient of CuCl2 concentrations; results were compared with those of the present standard method, Kirby-Bauer disk diffusion method on the Mueller Hinton medium. Finally, in order to evaluate the antibacterial activity of metals, Salmonella was inoculated on DHL agar plates. Subsequently, Japanese coins (1 yen, 5 yen, 10 yen, 50 yen, 100 yen and 500 yen coins) were placed on the agar and cultured at 310 K for 86 ks. Salmonella cultured in the presence of AlCl3 produces black color, while no blackening is observed with CuCl2, suggesting that copper possesses an antibacterial property against Salmonella. CuCl2 suppresses H2S production by Salmonella, as Cu2+ forms a transparent circle or ellipse (new halo) around the point at which CuCl2 had has been plated. The size of the new halo increases in direct proportion to the concentration of CuCl2. The halo is no longer visible at 0.034 mg of CuCl2 in our method, while the halo disappears with 4.34 mg of CuCl2 in the Kirby-Bauer method. Therefore, the present method is 129 times more sensitive than the standard method, suggesting increased usefulness and effectiveness in testing antibacterial activity. No FeS-dependent black circle is formed under any of the coins, with the exception of the 1-yen coin, which contains aluminum and no copper. Therefore, the copper-containing coins have an antibacterial effect.

著者

赤堀 俊和 新家 光雄 仲井 正昭 堤 晴美 野崎 隆宏 堀畑 聡 鈴木 亨 曽根 圭司

出版者

一般社団法人 軽金属学会

雑誌

軽金属 (ISSN:04515994)

巻号頁・発行日

vol.58, no.11, pp.604-610, 2008-11-30 (Released:2008-12-30)

参考文献数

13

被引用文献数

1

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Binary titanium alloys containing Nb or Ta, which are allergy-free and non-toxicity elements, were fabricated, and then the possibility of their application to various music instruments made of brass was investigated by the evaluation of corrosion characteristics, elastic modulus-density ratio (E/ρ), resonance frequency (f) and internal friction (Q−1) . The practical models of the mouthpieces of the trumpets made of the binary titanium alloys were also fabricated by precision casting method in order to compare directly with the sound characteristics of those made of brass and commercially pure Ti. The critical current density for the passivation of the Ti–Nb and Ti–Ta system alloys is approximately 40% lower than that of brass and nearly equal to or a little higher than that of commercially pure Ti. The Q−1 of the Ti–Nb and Ti–Ta system alloys with α″ phase drastically increase. The E/ρ and f of the Ti–Nb and Ti–Ta system alloys exhibit a positive relationship. The sound characteristics of practical mouthpieces of trumpets for a bass instrument can be controlled by changing the E/ρ and f of the alloys.

著者

新家 光雄 仲井 正昭 劉 恢弘 稗田 純子 趙 研 東 健司 上杉 徳照 石本 卓也 今野 豊彦 佐藤 和久 赤堀 俊和

出版者

名城大学

雑誌

基盤研究(A)

巻号頁・発行日

2012-04-01

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β型低弾性率Ti-29Nb-13Ta-4.6Zr合金(TNTZ)およびTi-Cr系合金につき、特にユビキタス元素である酸素(O)に注目し、従来では脆化をもたらすと考えられてきた高O濃度としたり、CrおよびO量を制御することにより、ω相、α”マルテンサイトあるいは双晶を適切に誘起すること、さらには超塑性歪加工、微粒子衝突やキャビテーションピーニングを施すことにより、両合金の高強度・高延性化、高疲労強度化、自己ヤング率調整機能の付与を達成した。TNTZでは、単結晶を用いて変形挙動を解析し、同合金単結晶が塑性的には異方性を示す、弾性的には等方性を示すことを見出した。