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論文

Release behavior of radionuclides from MOX fuels irradiated in a fast reactor during heating tests

田中 康介; 佐藤 勇*; 大西 貴士; 石川 高史; 廣沢 孝志; 勝山 幸三; 清野 裕; 大野 修司; 浜田 広次; 所 大志郎*; et al.

Journal of Nuclear Materials, 536, p.152119_1 - 152119_8, 2020/08

 被引用回数:0 パーセンタイル:0.01(Materials Science, Multidisciplinary)

照射済高速炉MOX燃料の加熱試験(2773K, 2973K及び3173K)により放出したFP等が沈着したサンプリングパーツにおける核種分析結果に基づき、高速炉MOX燃料からのFP等の放出挙動を評価した。その結果、FP核種の放出速度は、従来の軽水炉燃料で得られている知見と同等または低い値となる傾向を示した。また、燃料組成については、先行研究結果で得られた軽水炉燃料におけるデータのばらつきの範囲内にあることがわかった。

論文

Improvement of steam generator tube failure propagation analysis code LEAP for evaluation of overheating rupture

内堀 昭寛; 柳沢 秀樹*; 高田 孝; 栗原 成計; 浜田 広次; 大島 宏之

Journal of Nuclear Science and Technology, 56(2), p.201 - 209, 2019/02

 被引用回数:0 パーセンタイル:0.01(Nuclear Science & Technology)

ナトリウム冷却高速炉の蒸気発生器において、伝熱管破損時のナトリウム-水反応現象の影響による破損伝播の発生有無を評価することが重要な課題となっている。本研究では、既存の伝熱管破損伝播解析コードにおいて高温ラプチャ型破損伝播を評価対象に含めるため、これに対応する解析手法を開発した。液体ナトリウム中水蒸気噴出試験を解析し、同解析手法の適用性を確認した。

報告書

蒸気発生器における伝熱管破損時長時間事象進展解析コードLEAP-IIIの開発

内堀 昭寛; 柳沢 秀樹*; 高田 孝; 栗原 成計; 浜田 広次; 大島 宏之

JAEA-Research 2017-007, 61 Pages, 2017/07

JAEA-Research-2017-007.pdf:4.3MB

ナトリウム冷却高速炉の蒸気発生器に対する安全評価では、伝熱管破損時のナトリウム-水反応現象の影響による破損伝播の発生有無と水リーク率を評価することが必要である。既往研究において、ウェステージ型破損伝播を伴う長時間事象進展解析コードLEAP-IIが開発されたが、将来炉の新型SGでは水・蒸気系の高温・高圧化が指向されていることから、高温ラプチャ型破損伝播も評価対象に含めることが重要な課題となっている。そこで、本研究では高温ラプチャの発生有無を評価する解析モデルを構築し、LEAP-IIコードへ導入した。本解析モデル導入後の解析コードをLEAP-IIIとした。本解析モデルの機能確認として、伝熱管群の存在する体系におけるナトリウム-水反応試験を対象とした解析を実施した。本解析では水リーク管周辺における模擬伝熱管で高温ラプチャが発生する結果が得られ、解析モデルが正しく機能し、なおかつ保守的な評価結果を与えることを確認した。

論文

Poly(ether ether ketone) (PEEK)-based graft-type polymer electrolyte membranes having high crystallinity for high conducting and mechanical properties under various humidified conditions

濱田 崇; 長谷川 伸; 深沢 秀行*; 澤田 真一; 越川 博; 宮下 敦巳; 前川 康成

Journal of Materials Chemistry A, 3(42), p.20983 - 20991, 2015/11

 被引用回数:32 パーセンタイル:70.95(Chemistry, Physical)

燃料電池の本格普及のため、低加湿下でのプロトン導電率と高加湿下での機械強度を併せ持つ電解質膜が不可欠である。本研究は、膜強度の高いポリ(エーテルエーテルケトン) (PEEK)に着目し、放射線グラフト重合により高いイオン交換容量(IEC)を有するPEEK-グラフト型電解質膜(PEEK-PEM)を合成することで、導電率と機械的強度の両立を目指した。IEC=3.08mmol/gのPEEK-PEMは、80$$^{circ}$$Cにおいて、低加湿下(相対湿度30%)でナフィオンと同等の導電率、高加湿下(相対湿度100%)で1.4倍の引張強度(14MPa)を示した。さらに、PEEK-PEM (IEC=2.45mmol/g)を用いて作製した燃料電池は、高加湿下(相対湿度100%)でナフィオンと同等、低加湿下(相対湿度30%)でナフィオンの2.5倍の最大出力密度を示した。X線回析からPEEK-PEMは、グラフト重合中、結晶性が増加するため、高いIECを持つPEEK-PEMにおいても、高い機械的強度を示すことが明らかとなった。

論文

Welding technology on sector assembly of the JT-60SA vacuum vessel

芝間 祐介; 岡野 文範; 柳生 純一; 神永 敦嗣; 三代 康彦; 早川 敦郎*; 佐川 敬一*; 持田 務*; 森本 保*; 濱田 崇史*; et al.

Fusion Engineering and Design, 98-99, p.1614 - 1619, 2015/10

 被引用回数:4 パーセンタイル:33.51(Nuclear Science & Technology)

現在、建設中のJT-60SA装置では、高さ6.6m、大半径5mの二重壁トーラス構造で真空容器(150tons)を製作する。容器を10個のセクターに分割して製作し、これら分割セクターの製作が2014年に完了した。製作したセクターを現地で接続する段階にあり、この接続の初期では、セクターを直接突き合わせて溶接接続する。二つのセクター間を溶接接続するためには、溶接に必要な目違いやギャップの許容量を把握するという課題がある。他方、現地の組み立てでは、これらの許容量を満足するように管理されなければならない。本報告では、真空容器の最終セクターを含む組立方法の詳細について報告する。更に、分割製作されたセクターを直接接続する溶接技術、最終セクターの部分モックアップ溶接試験の結果を議論するとともに、現地製作の現状も報告する。

論文

The Development of a non-destructive analysis system with negative muon beam for industrial devices at J-PARC MUSE

反保 元伸*; 濱田 幸司*; 河村 成肇*; 稲垣 誠*; 伊藤 孝; 小嶋 健児*; 久保 謙哉*; 二宮 和彦*; Strasser, P.*; 吉田 剛*; et al.

JPS Conference Proceedings (Internet), 8, p.036016_1 - 036016_6, 2015/09

We developed a low-background muonic X-ray measurement system for nondestructive elemental depth-profiling analysis. A test experiment was performed using a multi-layered sample (34-$$mu$$m Al/140-$$mu$$m C/70-$$mu$$m Cu/500$$mu$$m LiF) and characteristic muonic X-rays from $$mu$$C, $$mu$$Cu, and $$mu$$F in the sample were successfully identified. A comparison was made between the relative intensity of the characteristic muonic X-rays and simulated muon depth profiles for several muon implantation energies.

論文

First-principles study of electronic and magnetic structures of CoFeB|Ta and CoFe|TaB heterostructures

濱田 智之*; 大野 隆央*; 前川 禎通

Molecular Physics, 113(3-4), p.314 - 318, 2014/07

 被引用回数:3 パーセンタイル:11.05(Chemistry, Physical)

The electronic and magnetic structures of the CoFeB|Ta and CoFe|TaB heterostructures were investigated from first principles in an attempt to clarify the effect of the Ta layer on the energetic stability and magnetisation of the heterostructures, which are used in magnetic random access memory devices.

論文

Implementation of the DFT+U method and constrained DFT calculations for $$U$$ and $$J$$ within a Pseudopotential formalism; Application to FeO and LaVO$$_{3}$$

濱田 智之*; 大野 隆央*; 前川 禎通

Journal of the Korean Physical Society, 62(12), p.2155 - 2159, 2013/06

 被引用回数:3 パーセンタイル:27.38(Physics, Multidisciplinary)

A first-principles density theory (DFT)+U method based on the pseudopotential (PP) method was developled to enable $$a$$ - $$priori$$ prediction of electronic structures of strongly-correlated electronic structures (SCES) systems. The method determines the radius of the localized electron orbitals of a SCES system and the Hubbard parameteres ${it U}$ and ${it J}$ for the electrons and calculates the electronic structure of the system by using the rotationally-invariant DFT + U method and using the determined radius and parameters. The electronic structure of FeO in the anti-ferromagnetic state was calculated by using the method, and the method could describe the electronic structure of FeO correctly, producing an insulating ground state for FeO with an indirect band gap of 1.88 eV.

論文

Tolerance of anhydrobiotic eggs of the tardigrade ${it Ramazzottius varieornatus}$ to extreme environments

堀川 大樹*; 山口 理美*; 坂下 哲哉; 田中 大介*; 浜田 信行*; 行弘 文子*; 桑原 宏和*; 國枝 武和*; 渡邊 匡彦*; 中原 雄一*; et al.

Astrobiology, 12(4), p.283 - 289, 2012/04

 被引用回数:23 パーセンタイル:68.9(Astronomy & Astrophysics)

クマムシの乾燥休眠状態である卵の孵化率について、宇宙空間の特徴的な極限環境要因である放射線(Heイオン線),極低温,高真空に対する耐性を調べた。その結果、50%が孵化できない線量が約500Gy, -196度に曝されても70%以上が孵化し、6$$times$$10$$^{-5}$$Paの高真空においた後でも孵化することができることがわかった。以上の結果から、宇宙空間であってもクマムシの耐性能力により、乾眠状態であるならば、存在できる可能性が示唆された。

論文

Evaluation of the relative biological effectiveness of carbon ion beams in the cerebellum using the rat organotypic slice culture system

吉田 由香里*; 鈴木 義行*; Al-Jahdari, W. S.*; 浜田 信行*; 舟山 知夫; 白井 克幸*; 加藤 弘之*; 坂下 哲哉; 小林 泰彦; 中野 隆史*

Journal of Radiation Research, 53(1), p.87 - 92, 2012/02

 被引用回数:8 パーセンタイル:42.05(Biology)

To clarify the relative biological effectiveness (RBE) values of carbon ion (C) beams in normal brain tissues, a rat organotypic slice culture system was used. The cerebellum was dissected from 10-day-old Wistar rats, cut parasagittally into approximately 600-$$mu$$m-thick slices and cultivated using a membrane-based culture system with a liquid-air interface. Slices were irradiated with 140 kV X-rays and 18.3 MeV/amu C-beams (linear energy transfer = 108 keV/$$mu$$m). After irradiation, the slices were evaluated histopathologically using hematoxylin and eosin staining, and apoptosis was quantified using the TdT-mediated dUTP-biotin nick-end labeling (TUNEL) assay. Disorganization of the external granule cell layer (EGL) and apoptosis of the external granule cells (EGCs) were induced within 24 h after exposure to doses of more than 5 Gy from C-beams and X-rays. In the early postnatal cerebellum, morphological changes following exposure to C-beams were similar to those following exposure to X-rays. The RBEs values of C-beams using the EGL disorganization and the EGC TUNEL index endpoints ranged from 1.4 to 1.5. This system represents a useful model for assaying the biological effects of radiation on the brain, especially physiological and time-dependent phenomena.

論文

Radiation-induced ICAM-1 expression via TGF-$$beta$$1 pathway on human umbilical vein endothelial cells; Comparison between X-ray and carbon-ion beam irradiation

清原 浩樹*; 石崎 泰樹*; 鈴木 義行*; 加藤 弘之*; 浜田 信行*; 大野 達也*; 高橋 健夫*; 小林 泰彦; 中野 隆史*

Journal of Radiation Research, 52(3), p.287 - 292, 2011/03

 被引用回数:14 パーセンタイル:51.62(Biology)

Radiation-induced intercellular adhesion molecule-1 (ICAM-1) expression on endothelial cells was investigated with the use of an inhibitor of transforming growth factor-beta1 (TGF-$$beta$$1) receptor kinase (SB431542) and the effects of X-ray and carbon-ion beam were compared. Expression of ICAM-1 was increased by X-ray and carbon-ion beam irradiation and decreased significantly with SB431542 after both irradiations. The expression of ICAM-1 by 2 Gy of carbon-ion beam irradiation was 6.7 fold higher than that of non-irradiated cells, while 5 Gy of X-ray irradiation increased the expression of ICAM-1 by 2.5 fold. According to ICAM-1 expression, the effect of carbon-ion beam irradiation was about 2.2, 4.4 and 5.0 times greater than that of the same doses of X-ray irradiation (1, 2 and 5 Gy, respectively). The present results suggested that radiation-induced ICAM-1 expression on human umbilical vein endothelial cells (HUVE cells) was, at least partially, regulated by TGF-$$beta$$1. Carbon-ion beam induced significantly higher ICAM-1 expression than X-ray.

論文

Anhydrobiosis-associated nuclear DNA damage and repair in the Sleeping Chironomid; Linkage with radioresistance

Gusev, O.*; 中原 雄一*; Vanyagina, V.*; Malutina, L.*; Cornette, R.*; 坂下 哲哉; 浜田 信行*; 黄川田 隆洋*; 小林 泰彦; 奥田 隆*

PLoS ONE (Internet), 5(11), p.e14008_1 - e14008_9, 2010/11

 被引用回数:49 パーセンタイル:75.31(Multidisciplinary Sciences)

これまでに、クリプトビオシス状態(体内の水分をほぼ完全に失っても生命を維持できる状態)のネムリユスリカは放射線耐性が上昇していることを明らかにしてきた。その原因として考えられてきたトレハロースによる生体分子保護機構に加えて、今回、高いDNA修復能力と活性酸素除去機構を発見した。コメットアッセイを用いて、クリプトビオシス状態でも70GyのHeイオンを浴びた幼虫と同程度の損傷(DNA切断)を負っていること、蘇生後約4日間でほぼ完全にこの損傷が修復できることがわかった。また、遺伝子発現解析により、クリプトビオシス誘導時には、DNA修復や活性酸素除去,シャペロンにかかわる遺伝子の発現が上昇することが明らかとなった。

論文

Distinct response of irradiated normal human fibroblasts and their bystander cells to heavy-ion radiation in confluent cultures

浜田 信行*; 岩川 眞由美*; 今留 香織*; 舟山 知夫; 坂下 哲哉; 楚良 桜*; Ni, M.*; 今井 高志*; 小林 泰彦

Journal of Radiation Research, 50(Suppl.A), P. A118, 2009/05

There is significant evidence for radiation-induced bystander effects; however, little information exists on the bystander effect of energetic heavy ions. Here we compared heavy-ion response of irradiated and bystander fibroblasts in confluent cultures. Bystander cells manifested a more transient apoptotic response and delayed p53 phosphorylation than irradiated cells did. More than half of the genes whose expression changed in bystander cells was downregulated, and most of the genes upregulated in irradiated cells were downregulated in bystander cells. The data highlight the distinct response of irradiated and bystander cells.

論文

Heavy-ion-induced bystander killing of human lung cancer cells; Role of gap junctional intercellular communication

原田 耕作*; 野中 哲生*; 浜田 信行*; 桜井 英幸*; 長谷川 正俊*; 舟山 知夫; 柿崎 竹彦*; 小林 泰彦; 中野 隆史*

Cancer Science, 100(4), p.684 - 688, 2009/04

 被引用回数:54 パーセンタイル:75.81(Oncology)

The aim of the present study was to clarify the mechanisms of cell death induced by heavy-ion irradiation focusing on the bystander effect in human lung cancer A549 cells. In microbeam irradiation, each of 1, 5 and 25 cells under confluent cell conditions was irradiated with 1, 5 or 10 particles of energetic carbon ions, and then the surviving fraction of the population was measured by a clonogenic assay in order to investigate the bystander effect of heavy-ions. In this experiment, the limited number of cells (0.0001-0.002%, 5-25 cells) under confluent cell conditions irradiated with 5 or 10 carbon ions resulted in an exaggerated 8-14% increase in cell death by clonogenic assay. However, these overshooting responses were not observed under exponentially growing cell conditions. Furthermore, these responses were inhibited in cells treated with an inhibitor of gap junctional intercellular communication (GJIC), whereas these were markedly enhanced by the addition of a stimulator of GJIC. The present results suggest that bystander cell killing by heavy-ions was induced mainly by direct cell-to-cell communication, such as GJIC, which might play important roles in the bystander responses.

論文

Ceramide induces myogenic differentiation and apoptosis in ${it Drosophila}$ Schneider cells

河村 英将*; 立井 一明*; 野中 哲生*; 大日方 英*; 服部 友保*; 小川 愛*; 風間 秀子*; 浜田 信行*; 舟山 知夫; 坂下 哲哉; et al.

Journal of Radiation Research, 50(2), p.161 - 169, 2009/03

 被引用回数:7 パーセンタイル:27.07(Biology)

Cells exposed to genotoxic stress, such as ionizing radiation and DNA damaging reagents, either arrest the cell cycle to repair the genome, or undergo apoptosis, depending on the extent of the DNA damage. DNA damage also has been implicated in various differentiation processes. It has been reported that $$gamma$$-ray exposure or treatment with DNA-damaging agents could induce myogenic differentiation in ${it Drosophila}$ Schneider cells. However, the mechanism underlying this process has been poorly understood. In this study, exposure of Schneider cells to X-rays or energetic carbon ion beams caused increase of TUNEL-positive cells and conversion of round-shaped cells to elongated cells. Both upregulation of genes related to myogenesis and increase of myosin indicate that the radiation-induced morphological changes of Schneider cells were accompanied with myogenic differentiation. Because the intracellular ceramide was increased in Schneider cells after exposure to X-ray, we examined whether exogenous ceramide could mimic radiation-induced myogenic differentiation. Addition of membrane-permeable C$$_{2}$$-ceramide to Schneider cells increased apoptosis and expression of myogenic genes. These results suggest that ceramide plays important roles in both apoptosis and the radiation-induced myogenic differentiation process.

論文

Energetic heavy ions overcome tumor radioresistance caused by overexpression of Bcl-2

浜田 信行*; 原 孝光*; 大村 素子*; 舟山 知夫; 坂下 哲哉; 楚良 桜; 横田 裕一郎; 中野 隆史*; 小林 泰彦

Radiotherapy and Oncology, 89(2), p.231 - 236, 2008/11

 被引用回数:23 パーセンタイル:59.17(Oncology)

Overexpression of Bcl-2 is frequent in human cancers and has been associated with the radioresistance. Here we investigated the potential impact of heavy ions on Bcl-2 overexpressing tumors. Bcl-2 cells (Bcl-2 overexpressing HeLa cells) and Neo cells (neomycin resistant gene-expressing HeLa cells) exposed to $$gamma$$-rays or heavy ions were assessed for the clonogenic survival, apoptosis and cell cycle distribution. Whereas Bcl-2 cells were more resistant to $$gamma$$-rays and helium ions (16.2 keV/$$mu$$m) than Neo cells, heavy ions (76.3-1610 keV/$$mu$$m) gave the comparable survival regardless of Bcl-2 overexpression. Carbon ions (108 keV/$$mu$$m) decreased the difference in the apoptotic incidence between Bcl-2 and Neo cells, and prolonged G$$_{2}$$/M arrest that occurred more extensively in Bcl-2 cells than in Neo cells. High-LET heavy ions overcome tumor radioresistance caused by Bcl-2 overexpression, which may be explained at least in part by the enhanced apoptotic response and prolonged G$$_{2}$$/M arrest. Thus, heavy-ion therapy may be a promising modality for Bcl-2 overexpressing radioresistant tumors.

論文

The Small-molecule Bcl-2 inhibitor HA14-1 sensitizes cervical cancer cells, but not normal fibroblasts, to heavy-ion radiation

浜田 信行*; 片岡 啓子*; 楚良 桜*; 原 孝光*; 大村 素子*; 舟山 知夫; 坂下 哲哉; 中野 隆史*; 小林 泰彦

Radiotherapy and Oncology, 89(2), p.227 - 230, 2008/11

 被引用回数:9 パーセンタイル:31.78(Oncology)

This is the first study to demonstrate that the small-molecule Bcl-2 inhibitor HA14-1 renders human cervical cancer cells and their Bcl-2 over expressing radioresistant counterparts, but not normal fibroblasts, more susceptible to heavy ions. Thus, Bcl-2 may be an attractive target for improving the efficacy of heavy-ion therapy.

論文

A LET-dependent decrease in the apoptotic response of normal human fibroblast cultures to isosurvival doses of $$gamma$$-rays and energetic heavy ions

浜田 信行*; Ni, M.*; 舟山 知夫; 坂下 哲哉; 楚良 桜*; 中野 隆史*; 小林 泰彦

宇宙生物科学, 22(2), p.41 - 45, 2008/10

Biological effectiveness varies with the linear energy transfer (LET) of ionizing radiation. Plentiful evidence has been presented demonstrating that at physically equivalent doses, high-LET energetic heavy ions are more cytotoxic and genotoxic than low-LET photons like X-rays and $$gamma$$-rays. Notwithstanding, its potential impact at isosurvival doses is yet to be characterized. Here we investigated the cell-killing effectiveness of $$gamma$$-rays (0.2 keV/$$mu$$m) and five different beams of heavy ions with LET ranging from 16.2 to 1610 keV/$$mu$$m in confluent cultures of normal human fibroblasts. The relative biological effectiveness based on the dose giving 10% clonogenic survival peaked at 108 keV/$$mu$$m. In cultures exposed to the 10% survival doses, the yield of apoptotic cells escalated with time postirradiation but declined with LET. Our results imply that the cell death mode differs with LET at isosurvival levels.

論文

Heavy-ion microbeam irradiation induces bystander killing of human cells

浜田 信行*; 原 孝光*; 大村 素子*; Ni, M.*; 舟山 知夫; 坂下 哲哉; 楚良 桜*; 中野 隆史*; 小林 泰彦

宇宙生物科学, 22(2), p.46 - 53, 2008/10

Significant evidence indicates that ionizing radiation causes biological effects in nonirradiated bystander cells having received signals from directly irradiated cells. There is little information available hitherto as to the bystander effect of energetic heavy ions; however, our previous work has shown that in confluent cultures of normal human fibroblast AG01522 cells, targeted exposure of 0.0003% of cells to microbeams of 18.3 MeV/u $$^{12}$$C (103 keV/$$mu$$m) and 13.0 MeV/u $$^{20}$$Ne (375 keV/$$mu$$m) ions can similarly cause almost 10% decreases in the clonogenic survival, and twofold increments in the incidence of apoptosis whose temporal kinetics varies between irradiated and bystander cells. Using this experimental system, here we further report that bystander responses of AG01522 cells to 17.5 MeV/u 20Ne ions (294 keV/$$mu$$m) are consistent with those to 18.3 MeV/u $$^{12}$$C and 13.0 MeV/u $$^{20}$$Ne ions. We also demonstrate that such bystander-induced reductions in the survival are less pronounced and occur independently of Bcl-2 overexpression in human cervical cancer HeLa cells.

論文

Exposure of normal human fibroblasts to heavy-ion radiation promotes their morphological differentiation

楚良 桜*; 浜田 信行*; 原 孝光*; 舟山 知夫; 坂下 哲哉; 横田 裕一郎; 中野 隆史*; 小林 泰彦

宇宙生物科学, 22(2), p.54 - 58, 2008/10

Here we investigated the potential impact of energetic heavy ions on fibroblast differentiation. The differentiation pattern was morphologically determined at days 3 and 5 after exposure to graded dose of $$gamma$$-rays (0.2 keV/$$mu$$m) or carbon ions (18.3 MeV/u, 108 keV/$$mu$$m). The cells irradiated with higher doses progressed toward later differentiation stages as time goes postirradiation, but underwent fewer cell divisions. Thus, radiation exposure accelerated morphological differentiation, for which carbon ions were more effective than $$gamma$$-rays. The relative biological effectiveness of carbon ions for differentiation was higher than that for the clonogenic survival, and this was the most case for terminally differentiated cells that may not divide any more. The results are suggestive of the distinct mechanism underlying inactivation of clonogenic potential between radiation qualities, such that the contribution of the differentiation to heavy ion-induced reductions in the survival is greater than to those induced by photons. Such accelerated differentiation could be a protective mechanism that minimizes further expansion of aberrant cells.

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