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Journal Articles

Neutron diffraction study on the deuterium composition of nickel deuteride at high temperatures and high pressures

Saito, Hiroyuki*; Machida, Akihiko*; Hattori, Takanori; Sano, Asami; Funakoshi, Kenichi*; Sato, Toyoto*; Orimo, Shinichi*; Aoki, Katsutoshi*

Physica B; Condensed Matter, 587, p.412153_1 - 412153_6, 2020/06

 Times Cited Count:1 Percentile:23.44(Physics, Condensed Matter)

The site occupancy of deuterium (D) atoms in face-centered-cubic nickel (fcc Ni) was measured along a cooling path from 1073 to 300 K at an initial pressure of 3.36 GPa via in situ neutron powder diffraction. Deuterium atoms predominantly occupy the octahedral (O) sites and slightly occupy the tetrahedral (T) sites of the fcc metal lattice. The O-site occupancy increases from 0.4 to 0.85 as the temperature is lowered from 1073 to 300 K. Meanwhile, the T-site occupancy remains c.a. 0.02. The temperature-independent behavior of the T-site occupancy is unusual, and its process is not yet understood. From the linear relation between the expanded lattice volume and D content, a D-induced volume expansion of 2.09(13) ${AA $^{3}$/D}$ atom was obtained. This value is in agreement with the values of 2.14-2.2 ${AA $^{3}$/D}$ atom previously reported for Ni and Ni$$_{0.8}$$ Fe$$_{0.2}$$ alloy.

Journal Articles

Crystal and magnetic structures of double hexagonal close-packed iron deuteride

Saito, Hiroyuki*; Machida, Akihiko*; Iizuka, Riko*; Hattori, Takanori; Sano, Asami; Funakoshi, Kenichi*; Sato, Toyoto*; Orimo, Shinichi*; Aoki, Katsutoshi*

Scientific Reports (Internet), 10, p.9934_1 - 9934_8, 2020/06

 Times Cited Count:0 Percentile:0(Multidisciplinary Sciences)

Neutron powder diffraction profiles were collected for iron deuteride (FeDx) while the temperature decreased from 1023 to 300 K for a pressure range of 4-6 GPa. The $$varepsilon$$' deuteride with a double hexagonal close-packed (dhcp) structure, which coexisted with other stable or metastable deutrides at each temperature and pressure condition, formed solid solutions with a composition of FeD$$_{0.68(1)}$$ at 673 K and 6.1 GPa and FeD$$_{0.74(1)}$$ at 603 K and 4.8 GPa. Upon stepwise cooling to 300 K, the D-content x increased to a stoichiometric value of 1.0 to form monodeuteride FeD$$_{1.0}$$. In the dhcp FeD$$_{1.0}$$ at 300 K and 4.2 GPa, dissolved D atoms fully occupied the octahedral interstitial sites, slightly displaced from the octahedral centers in the dhcp metal lattice, and the dhcp sequence of close-packed Fe planes contained hcp-stacking faults at 12%. Magnetic moments with 2.11 $$pm$$ 0.06 B/Fe-atom aligned ferromagnetically in parallel on the Fe planes.

Journal Articles

Hexagonal close-packed iron hydride behind the conventional phase diagram

Machida, Akihiko*; Saito, Hiroyuki*; Hattori, Takanori; Sano, Asami; Funakoshi, Kenichi*; Sato, Toyoto*; Orimo, Shinichi*; Aoki, Katsutoshi*

Scientific Reports (Internet), 9(1), p.12290_1 - 12290_9, 2019/08

 Times Cited Count:7 Percentile:63.65(Multidisciplinary Sciences)

Hexagonal close-packed iron hydride, hcp FeHx, is absent from the conventional phase diagram of the Fe-H system, although hcp metallic Fe exists stably over extensive temperature ($$T$$) and pressure ($$P$$) conditions, including those corresponding to the Earth's inner core. ${{it In situ}}$ X-ray and neutron diffraction measurements at temperatures ranging from 298 to 1073 K and H pressures ranging from 4 to 7 GPa revealed that the hcp hydride was formed for FeH$$_{x}$$ compositions when $$x < 0.6$$. Hydrogen atoms occupied the octahedral interstitial sites of the host metal lattice both partially and randomly. The hcp hydride exhibited a H-induced volume expansion of 2.48(5) $AA $^{3}$$/H-atom, which was larger than that of the face-centered cubic (fcc) hydride. The hcp hydride showed an increase in $$x$$ with $$T$$, whereas the fcc hydride showed a corresponding decrease. The present study provides guidance for further investigations of the Fe-H system over an extensive $$x$$-$$T$$-$$P$$ region.

Journal Articles

Observation of dynamics and modification of solid surface using a picosecond soft X-ray laser

Nishikino, Masaharu; Kawachi, Tetsuya; Hasegawa, Noboru; Ishino, Masahiko; Minami, Yasuo*; Suemoto, Toru*; Onishi, Naofumi*; Ito, Atsushi*; Sato, Katsutoshi*; Faenov, A.*; et al.

X-Ray Lasers and Coherent X-Ray Sources; Development and Applications XI (Proceedings of SPIE, Vol.9589), p.958902_1 - 958902_7, 2015/09

Journal Articles

A Laser-plasma-produced soft X-ray laser at 89 eV generates DNA double-strand breaks in human cancer cells

Sato, Katsutoshi*; Nishikino, Masaharu; Kawachi, Tetsuya; Shimokawa, Takashi*; Imai, Takashi*; Teshima, Teruki*; Nishimura, Hiroaki*; Kando, Masaki

Journal of Radiation Research, 56(4), p.633 - 638, 2015/07

 Times Cited Count:1 Percentile:8.43(Biology)

While X-ray laser is expected to be widely applied to biomedical studies, this has not been achieved to date and its biological effects such as DNA damage have not been evaluated. As a first step for its biological application, we developed a culture cell irradiation system using laser-plasma soft X-ray laser and investigated whether the soft X-ray laser is able to induce the DNA double strand breaks (DSBs) in living cells or not. The human adenocarcimona cell line A549 was irradiated with the soft X-ray laser at a photon energy of 89 eV and then the repair focus formation of the DSBs was assessed by immunofluorescence staining with anti-phosphorylated DNA-PKcs antibody. As a result, the phosphorylated DNA-PKcs foci were clearly identified even with just a single shot of the soft X-ray laser. In this study, we successfully demonstrated for the first time that soft X-ray laser at 89 eV induced the DNA double strand breaks in living cells.

Journal Articles

True Boundary for the formation of homoleptic transition-metal hydride complexes

Takagi, Shigeyuki*; Iijima, Yuki*; Sato, Toyoto*; Saito, Hiroyuki; Ikeda, Kazutaka*; Otomo, Toshiya*; Miwa, Kazutoshi*; Ikeshoji, Tamio*; Aoki, Katsutoshi*; Orimo, Shinichi*

Angewandte Chemie; International Edition, 54(19), p.5650 - 5653, 2015/05

 Times Cited Count:27 Percentile:70.75(Chemistry, Multidisciplinary)

Journal Articles

Site occupancy of interstitial deuterium atoms in face-centred cubic iron

Machida, Akihiko; Saito, Hiroyuki; Sugimoto, Hidehiko*; Hattori, Takanori; Sano, Asami; Endo, Naruki*; Katayama, Yoshinori; Iizuka, Riko*; Sato, Toyoto*; Matsuo, Motoaki*; et al.

Nature Communications (Internet), 5, p.5063_1 - 5063_6, 2014/09

 Times Cited Count:34 Percentile:81.72(Multidisciplinary Sciences)

Iron hydride FeH$$_x$$, is thermodynamically stable only at high hydrogen pressure of several GPa. To investigate the hydrogenation process and hydrogen state in iron hydride, it is necessary to carry out the in-situ measurement under high pressure and high temperature. In this study, we performed the in-situ neutron diffraction measurement of Fe-D system using the high pressure neutron diffractometer PLANET in the MLF, J-PARC, and determined the deuterium occupying sites and occupancies in fcc-FeD$$_x$$. We found the minor occupation of tetrahedral sites under high pressure and high temperature. We considered the mechanism of the minor occupation based on the Quantum-mechanical calculation.

Journal Articles

Unusual sevenfold coordination of Ru in complex hydride Na$$_{3}$$RuH$$_{7}$$; Prospect for formation of [FeH$$_{7}$$]$$^{3-}$$ anion

Takagi, Shigeyuki*; Ikeshoji, Tamio*; Matsuo, Motoaki*; Sato, Toyoto*; Saito, Hiroyuki; Aoki, Katsutoshi; Orimo, Shinichi*

Applied Physics Letters, 103(11), p.113903_1 - 113903_4, 2013/09

 Times Cited Count:9 Percentile:42.59(Physics, Applied)

Journal Articles

Formation process of perovskite-type hydride LiNiH$$_{3}$$; ${it In situ}$ synchrotron radiation X-ray diffraction study

Sato, Ryutaro*; Saito, Hiroyuki; Endo, Naruki; Takagi, Shigeyuki*; Matsuo, Motoaki*; Aoki, Katsutoshi; Orimo, Shinichi*

Applied Physics Letters, 102(9), p.091901_1 - 091901_4, 2013/03

 Times Cited Count:21 Percentile:70.12(Physics, Applied)

Journal Articles

Density-functional study of perovskite-type hydride LiNiH$$_{3}$$ and its synthesis; Mechanism for formation of metallic perovskite

Takagi, Shigeyuki*; Saito, Hiroyuki; Endo, Naruki; Sato, Ryutaro*; Ikeshoji, Tamio*; Matsuo, Motoaki*; Miwa, Kazutoshi*; Aoki, Katsutoshi; Orimo, Shinichi*

Physical Review B, 87(12), p.125134_1 - 125134_6, 2013/03

 Times Cited Count:9 Percentile:44.68(Materials Science, Multidisciplinary)

Journal Articles

Formation of an Fe-H complex anion in YFe$$_{2}$$; Adjustment of imbalanced charge by additional Li as an electron donor

Matsuo, Motoaki*; Saito, Hiroyuki; Machida, Akihiko; Sato, Ryutaro*; Takagi, Shigeyuki*; Miwa, Kazutoshi*; Watanuki, Tetsu; Katayama, Yoshinori; Aoki, Katsutoshi; Orimo, Shinichi*

RSC Advances (Internet), 3(4), p.1013 - 1016, 2013/01

 Times Cited Count:16 Percentile:53.51(Chemistry, Multidisciplinary)

Journal Articles

Application of laser plasma X-ray beam in radiation biology

Nishikino, Masaharu; Sato, Katsutoshi; Hasegawa, Noboru; Ishino, Masahiko; Kawachi, Tetsuya; Imazono, Takashi; Numasaki, Hodaka*; Teshima, Teruki*; Nishimura, Hiroaki*

X-Ray Lasers 2010; Springer Proceedings in Physics, Vol.136, p.301 - 306, 2011/12

Temporal sequences of physical and physicochemical stage of actions in biological systems irradiated with energetic radiation take place with in the order of picoseconds. The short duration of laser produced plasma source could be used as a new source in contrast to conventional X-ray sources in investigating the mechanism of the affect of radiation on biological cells. We have started to develop a focused X-ray beam irradiation system for use in studying radiobiological effects on cells, and demonstrated a preliminary study of radiation effect on culture cells irradiated with laser produced plasma Ka X-rays and the X-ray laser.

Journal Articles

Measurement of DNA double-strand break yield in human cancer cells by high-current, short-duration bunches of laser-accelerated protons

Yogo, Akifumi; Sato, Katsutoshi; Nishikino, Masaharu; Maeda, Takuya*; Sakaki, Hironao; Hori, Toshihiko*; Ogura, Koichi; Nishiuchi, Mamiko; Teshima, Teruki*; Nishimura, Hiroaki*; et al.

Japanese Journal of Applied Physics, 50(10), p.106401_1 - 106401_7, 2011/10

 Times Cited Count:8 Percentile:37.66(Physics, Applied)

Journal Articles

Development of laser plasma X-ray microbeam irradiation system and radiation biological application

Sato, Katsutoshi; Nishikino, Masaharu; Numasaki, Hodaka*; Kawachi, Tetsuya; Teshima, Teruki*; Nishimura, Hiroaki*

Denki Gakkai Rombunshi, C, 130(10), p.1800 - 1805, 2010/10

no abstracts in English

Journal Articles

$${gamma}$$-H2AX and phosphorylated ATM focus formation in cancer cells after laser plasma X irradiation

Sato, Katsutoshi; Nishikino, Masaharu; Okano, Yasuaki*; Oshima, Shinsuke*; Hasegawa, Noboru; Ishino, Masahiko; Kawachi, Tetsuya; Numasaki, Hodaka*; Teshima, Teruki*; Nishimura, Hiroaki*

Radiation Research, 174(4), p.436 - 445, 2010/10

 Times Cited Count:16 Percentile:53.54(Biology)

Usefulness of laser-plasma X-ray pulse for medical and radiation biological studies was investigated and compared with that of conventional sources such as those obtained from a linear accelerator. A cell irradiation system was developed which uses Copper-K$${alpha}$$ (8 keV) lines from an ultra-short high intensity laser to produce plasma. The absorbed dose of the 8 keV laser-plasma X-ray pulse was accurately estimated with Gafchromic EBT film. When the cells were irradiated with approximately 2 Gy of laser plasma X-ray, the circular regions on $${gamma}$$-H2AX positive cells could be clearly identified. Moreover, the number of $${gamma}$$-H2AX and phosphorylated ataxia telangiectasia mutated (ATM) foci induced by 8 keV laser plasma X-ray were comparable to those induced by 4MV X-ray. These results indicate that the laser plasma X-ray source can be useful for radiation biological studies.

Journal Articles

Application of laser produced plasma K$$alpha$$ X-ray probe in radiation biology

Nishikino, Masaharu; Sato, Katsutoshi; Hasegawa, Noboru; Ishino, Masahiko; Oshima, Shinsuke*; Okano, Yasuaki*; Kawachi, Tetsuya; Numasaki, Hodaka*; Teshima, Teruki*; Nishimura, Hiroaki*

Review of Scientific Instruments, 81(2), p.026107_1 - 026107_3, 2010/02

 Times Cited Count:22 Percentile:70.29(Instruments & Instrumentation)

An X-ray generation and exposure system dedicated for radiation biology is developed. An X-ray pulse of 8.0 keV in energy as short as 1 ps is generated with a fs-laser pulse, and sample cells are irradiated through a specially designed cell dish with a silicon nitride membrane. DNA double-strand breaks in a nucleus of a human caner cell are caused by X-ray irradiation, and similar DNA breaks are obtained to those with the conventional X-ray source. This result demonstrates feasibility of radiobiological study with a single burst of X-rays shining on a single cell specimen.

Journal Articles

Application of laser-accelerated protons to the demonstration of DNA double-strand breaks in human cancer cells

Yogo, Akifumi; Sato, Katsutoshi; Nishikino, Masaharu; Mori, Michiaki; Teshima, Teruki*; Numasaki, Hodaka*; Murakami, Masao*; Demizu, Yusuke*; Akagi, Takashi*; Nagayama, Shinichi*; et al.

Applied Physics Letters, 94(18), p.181502_1 - 181502_3, 2009/05

 Times Cited Count:95 Percentile:94.5(Physics, Applied)

Journal Articles

Development of a single-crystal X-ray diffraction system for hydrostatic-pressure and low-temperature structural measurement and its application to the phase study of quasicrystals

Watanuki, Tetsu; Machida, Akihiko; Ikeda, Tomohiro*; Omura, Ayako*; Kaneko, Hiroshi; Aoki, Katsutoshi; Sato, Taku*; Tsai, A. P.*

Philosophical Magazine, 87(18-21), p.2905 - 2911, 2007/06

 Times Cited Count:42 Percentile:87.78(Materials Science, Multidisciplinary)

We have constructed a single-crystal synchrotron X-ray diffraction system to precisely study the structure under hydrostatic pressure conditions at low temperatures and applied it to a study on the phase transition phenomena of a Cd-Yb periodic approximant and a Cd-Yb quasicrystal. Four phases were newly observed for the 1/1 approximant crystal in a $$P-T$$ span up to 5.2 GPa and down to 10 K. The innermost part of the atomic clusters of Cd$$_{4}$$ tetrahedra exhibited various orientational ordering sensitively depending on pressure and temperature. High pressure diffraction measurements using a highly parallel synchrotron X-ray beam and a hydrostatically compressed single crystal enabled us to detect the weak diffractions due to the subtle structural changes.

Journal Articles

Pressure-induced phase transitions in the Cd-Yb periodic approximant to a quasicrystal

Watanuki, Tetsu; Machida, Akihiko; Ikeda, Tomohiro*; Aoki, Katsutoshi; Kaneko, Hiroshi; Shobu, Takahisa; Sato, Taku*; Tsai, A. P.*

Physical Review Letters, 96(10), p.105702_1 - 105702_4, 2006/03

 Times Cited Count:28 Percentile:77.14(Physics, Multidisciplinary)

The phase study of a Cd-Yb 1/1 approximant crystal over a wide pressure and temperature range is crucial for the comparison study between periodic and quasi-periodic crystals. The Cd4 tetrahedra, the most inner part of the atomic clusters, exhibited various structural ordering in the orientation sensitive to pressure and temperature. Five ordered phases appeared in a P-T span up to 5.2 GPa and down to 10K. The propagation direction of ordering alternated from [110] to $$<$$111$$>$$ at about 1.0 GPa and again to [110] at 3.5-4.3 GPa. The primarily ordered phases that appeared by cooling to 210-250K between 1-5.2 GPa further transformed to finely ordered ones at 120-155K. In addition to the original short-range type interaction, a long-range type interaction was likely developed under pressure to lead to the primary ordering of Cd4 tetrahedra. Coexistence of the two different type interactions is responsible for the complicated phase behavior.

JAEA Reports

Evaluation of dose attenuation factor of armored car against radiation accidents

Sato, Tatsuhiko; Fujii, Katsutoshi; Murayama, Takashi; Sakamoto, Yukio; Yamaguchi, Yasuhiro; Sato, Yukio*; Soma, Nobuyuki*; Fujisaki, Noboru*; Hara, Satoshi*; Aikawa, Yukio*; et al.

JAERI-Tech 2002-028, 20 Pages, 2002/03

JAERI-Tech-2002-028.pdf:5.01MB

Tokyo Fire Department developed an armored car against radiation accidents. Dose attenuation factors of the radiation shields had been determined by a simple estimation, and a more precise evaluation was required. By request from Tokyo Fire Department, a precise evaluation of the dose attenuation factor was carried out. The evaluation was done by a Monte Carlo radiation transport simulation code MCNP4B. Benchmark experiments using neutron and gamma ray sources were also performed for ensuring the evaluation method. As a result, it was found out that doses of neutron and gamma ray were attenuated to approximately 10% and 25% by the thickest shield, respectively. These values were close to the ones which had already obtained by the simple estimation.

58 (Records 1-20 displayed on this page)