著者

新家 光雄 武田 淳仁 赤堀 俊和 戸田 裕之 鈴木 亨 渡邊 勝美 山下 正文 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.55, no.12, pp.642-645, 2005 (Released:2006-02-24)

参考文献数

8

被引用文献数

1

著者

高城 健 岡田 義清 白壁 和彦 古橋 廣崇 榎本 真悟 谷知 正章 丸田 紘史 安武 優一 栗原 千枝 戸田 裕之 東山 正明 渡辺 知佳子 髙本 俊介 冨田 謙吾 清水 邦夫 永尾 重昭 三浦 総一郎 穂苅 量太

出版者

消化器心身医学研究会

雑誌

消化器心身医学 (ISSN:13408844)

巻号頁・発行日

vol.23, no.1, pp.2-5, 2016 (Released:2016-09-01)

参考文献数

29

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近年,心的外傷後ストレス障害(post-traumatic stress disorder: PTSD)と過敏性腸症候群(irritable bowel syndrome: IBS)の関連性が指摘されており,一方で精神疾患と腸内細菌との関連性が指摘されている。また,IBSでは腸管粘膜における脳由来神経栄養因子(brain-derived neurotrophic factor: BDNF)の発現が増加するとの報告もある。今回我々は,本学で開発されたPTSD動物モデルを用い,腸内細菌叢や腸管粘膜におけるBDNF発現の変化について検討した。シャトル箱を用いてラットに逃避不能の電撃を負荷すると,後の行動観察でラットはPTSD,学習性無力(learned helplessness: LH),indeterminateのいずれかの行動パターンを呈することが判明した。行動パターンによって腸内細菌叢の構成が異なり,PTSD群ではBacteroidetes,LH群ではProteobacteriaの割合が増加する傾向がみられた。またLH群では,近位結腸のBDNF発現が増加する傾向がみられた。これらの変化がmicrobiota-gut-brain axisに関連し,行動変化や消化管機能に影響を与えている可能性がある。

著者

古賀 農人 戸田 裕之 木下 学 吉野 相英

出版者

一般社団法人 日本エンドトキシン・自然免疫研究会

雑誌

エンドトキシン・自然免疫研究 (ISSN:24341177)

巻号頁・発行日

vol.22, pp.30-34, 2019 (Released:2019-11-06)

参考文献数

4

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Most of the current depression drugs have been developed based on the monoamine hypothesis. However, about 30% of patients indicate resistance to medication, and patients with relatively mild depression get only a small benefit from antidepressants. In addition, although an increase in monoamine concentration in synaptic gaps by monoamine transporter inhibition occurs within a relatively short time, it takes about six weeks to show an antidepressant effect in actual clinical settings. There are cases in which an antidepressant effect is observed for drugs that do not regulate the amount of monoamine. These facts suggest the presence of a variety of pathophysiologies in depression and depressive symptoms. Recently, a relationship between the onset of depression and the expression levels of immune-related molecules such as cytokines in the blood and the brain derived from patients with depression has been pointed out. Although there is so far no medication targeting neuroinflammation, many recent studies have shown that inflammation is not negligible and a significant factor in the pathogenesis of depression. Therefore, it is meaningful to focus on inflammation for elucidating the pathogenesis and developing medications. In this paper, we describe the pathogenesis pathways known to be involved in the inflammation, the serotonin hypothesis, hypothalamic-pituitary-adrenal axis hypothesis, and neurodegeneration/neurogenesis hypothesis and describe the applications to therapy and preventions based on them.

著者

水谷 京平 戸田 裕之 綿貫 雅敏 杉浦 協司 竹下 裕市

出版者

公益社団法人 日本鋳造工学会

雑誌

鋳造工学 全国講演大会講演概要集

巻号頁・発行日

vol.162, pp.96-96, 2013

著者

小林 正和 杉浦 協司 竹下 裕市 戸田 裕之

出版者

公益社団法人 日本鋳造工学会

雑誌

鋳造工学 (ISSN:13420429)

巻号頁・発行日

vol.86, no.3, pp.209-215, 2014

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<p>  The feasibility of applying the fluidized bed furnace to the solution and aging treatments of aluminum alloys was assessed by examining concerns such as the efficiency of heat treatments and delay of quenching, together with its merits such as the shortening of heat treatment and the possibility of high temperature heat treatments.</p><p>  It was concluded that this method realizes high efficiency of heat treatments, which is comparable to that attainable with the combination of a salt bath and oil bath. By suppressing the delay time within 20 to 30sec. after the removal of works from the fluidized bed furnace, no degradation in mechanical properties occurs. The allowable delay time is dependent on the work size. The solution treatment time can be shortened to 60min. or below. Good mechanical properties were obtained even with a short solution treatment time of 15min. depending on the size and thickness of the work. This also enables suppression of pore growth at the same time. In addition, high temperature heat treatment at around ternary eutectic temperatures was realized by precise temperature control, thereby realizing superior mechanical properties and shorter heat treatment time.</p>

著者

桑水流 理 寺西 正輝 小林 正和 戸田 裕之

出版者

公益財団法人 高輝度光科学研究センター

雑誌

SPring-8/SACLA利用研究成果集 (ISSN:21876886)

巻号頁・発行日

vol.9, no.6, pp.383-390, 2021-11-29 (Released:2021-10-29)

参考文献数

16

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板状の介在物粒子を含むアルミニウム鋳造合金の疲労破壊挙動を放射光 CT および大規模有限要素解析により検証した。疲労亀裂は主として介在物と母相の界面剥離から生じた。界面剥離と介在物粒子の破損はほぼ同時に多数発生し、多数の空隙を生じさせた。単一の亀裂の進展速度は遅く、多数の空隙が合体することで、亀裂は進展した。材料表面では Al 母相の塑性ひずみが蓄積し易く、Al 母相のひずみ硬化による応力増加が、材料表面近傍での介在物の破損を生じさせた。

著者

アギアル デ ソウザ ヴィニシウス 桑水流 理 何 惠安 戸田 裕之 小林 正和

出版者

一般社団法人 日本機械学会

雑誌

M&M材料力学カンファレンス

巻号頁・発行日

vol.2013, pp._OS0311-1_-_OS0311-3_, 2013

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The objective of this study is to evaluate the stress/strain distribution on a cast aluminum alloy (AC4CH-T6) employing image based nonlinear elasto-plastic finite element analysis. The numerical analysis was performed to simulate a uni-axial tension test. The geometry of the finite element model includes an aluminum matrix, silicon and inter-metallic particles which were obtained by the synchrotron X-ray micro-computed tomography (XMCT) technique. In order to create a proper finite element mesh, the Standard Triangle Language (STL) generated from the XMCT segmented volume was treated to remove geometric and structural irregularities. Results are discussed in terms of the number of elements necessary to accurately represent the stress/strain fields and the necessary computational time to simulate the problem. Additionally, results enabled visualizing the stress/strain distributions, stress concentration, and the stress/strain evolution on the three solids of interest.

著者

松村 圭悟 アギアルデソウザ ヴィニシウス 桑水流 理 小林 正和 戸田 裕之

出版者

一般社団法人 日本機械学会

雑誌

M&M材料力学カンファレンス

巻号頁・発行日

vol.2014, pp._OS1204-1_-_OS1204-3_, 2014

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The crack initiation mechanism of cast aluminum alloy was addressed to quantitatively evaluate the fatigue strength. The synchrotron radiation microtomography was employed to visualize the three-dimensional damage around pores and Si particles. Two types of specimens were prepared for the low cycle fatigue test. The temperature of solution treatment was different, and it yields a difference in the shape of Si particles. After a certain cycles of fatigue, a catastrophic damage around many Si particles happened and they connected to each other so as to form a crack. The scanning electron microscopy after the test showed that the type of damage was the break of long Si particles or the interface debonding around round Si particles.

著者

桑水流 理 松村 圭悟 アギアルデソウザ ヴィニシウス 小林 正和 戸田 裕之

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.64, no.11, pp.570-575, 2014

被引用文献数

4

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The crack initiation mechanism of cast aluminum alloy was addressed to quantitatively evaluate the fatigue strength. We employed the synchrotron radiation microtomography to visualize the three-dimensional damages around pores and silicon particles. Two types of specimens underwent a low-cycle fatigue test. The temperature of solution treatment was different, and it yielded a difference in the shape, size and distribution of silicon particles. After a certain cycles of fatigue, a catastrophic damage around many silicon particles occurred, and they connected to each other so as to form a crack especially within the high stressed region around a relatively large pore. The scanning electron microscopy after the test showed that the type of damage was the breakage of long-shaped silicon particles or the aluminum–silicon interface debonding of round silicon particles. The high temperature solution treatment facilitated the interface debonding by the enlargement of silicon particles.

著者

山田 隆介 戸田 裕之 竹内 晃久 ベーゼル 靖子

出版者

公益社団法人 日本鋳造工学会

雑誌

鋳造工学 (ISSN:13420429)

巻号頁・発行日

vol.89, no.1, pp.10-16, 2017

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<p>  A single-distance phase retrieval technique was applied to the contrast-enhanced phase-sensitive imaging of micro segregation in die-cast aluminum alloy. Contrast between regions with and without micro segregation, spatial resolution and signal-to-noise ratio were evaluated to clearly differentiate micro segregations whose density difference from the matrix aluminum is small, making it difficult to visualize and differentiate them using ordinary absorption-contrast imaging. Since spatial resolution more or less drops during the phase retrieval process, a combination of the high-contrast phase-contrast imaging and the high-resolution absorption-contrast imaging was applied to reveal 3D microstructure/fracture relationship in an in-situ tensile test. Each phase-contrast image was registered with a corresponding absorption-contrast image to examine the positional relationship between the fracture path and micro segregation. A sectioning technique was also applied to identify the source of density difference. The results confirmed that three-dimensionally connected bands of micro segregations provide a preferential path for fracture in the die-cast aluminum alloy investigated. The observations suggest that the control of the 3D spatial distribution of micro segregation bands is of crucial importance for enhancing mechanical properties effectively even if its elimination is physically difficult.</p>

著者

寺西 正輝 桑水流 理 小林 正和 戸田 裕之

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.84, no.863, pp.18-00028, 2018 (Released:2018-07-25)

参考文献数

23

被引用文献数

1

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Fatigue crack in cast aluminum alloys subject to low-cycle fatigue is initiated mainly by the fracture of Si particles. To investigate the mechanism of Si particle fracture, we carried out the geometrical measurements and finite element analysis for a lot of Si particles in their actual geometrical configuration. The synchrotron X-ray CT was used for the geometrical measurement and the image-based finite element modeling. The fracture of Si particles were detected as a source of crack initiation from the CT images captured during the fatigue test. The large-scale voxel finite element model contains the outer surface, pores, Si and intermetallics. The number of elements was about 150 million. Two cycles of loading were calculated. The finite element analysis and its post-processing were performed on the supercomputers by the massively-parallel computing. The result of finite element analysis showed that the first principal stress was concentrated around the aligned or gathered Si particles, and the gradual increase by cyclic loading in the stress of the Si particles appeared near the outer surface and pores. Moreover, the result of geometrical measurements showed that the volume, shape index and adjacency index of each Si particle could be used to evaluate the likelihood of particle fracture. The probability of particle fracture was statistically evaluated with respect to those geometrical and mechanical parameters. The relationship between mechanical and geometrical parameters were also examined. As the result, the criteria of fractured Si particle was proposed by using the combination of geometrical and mechanical parameters.

著者

澤田 健一 戸田 裕之 長谷川 晃

出版者

一般社団法人電子情報通信学会

雑誌

電子情報通信学会ソサイエティ大会講演論文集

巻号頁・発行日

vol.1995, no.1, 1995-09-05

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ダークリトン(暗いソリトン)は、明るいソリトンに比べて光増幅器雑音をはじめとする線形波や隣接ソリトンとの相互作用の影響が少ないため、より伝送容量が増大できると考えられている。我々は、前回対称駆動マッハーツェンダー変調器によるダークソリトン通信用光源について報告した。今回、この光源を用いたダークソリトン通信の検出方法の比較検討を行ったので報告する。

著者

戸田 裕之 山本 信 小林 正和 小林 俊郎 Qian Lihe 上杉 健太朗

出版者

社団法人日本材料学会

雑誌

学術講演会講演論文集

巻号頁・発行日

vol.56, pp.85-86, 2007-05-18

著者

赤堀 俊和 新家 光雄 原田 雅章 武田 淳仁 戸田 裕之 桂 成基 竹内 力 福井 壽男

出版者

日本金属学会

雑誌

日本金屬學會誌 = Journal of the Japan Institute of Metals (ISSN:00214876)

巻号頁・発行日

vol.69, no.1, pp.96-102, 2005-01-20

被引用文献数

1