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Amekura, Hiroshi*; Chettah, A.*; Narumi, Kazumasa*; Chiba, Atsuya*; Hirano, Yoshimi*; Yamada, Keisuke*; Yamamoto, Shunya*; Leino, A. A.*; Djurabekova, F.*; Nordlund, K.*; et al.
Nature Communications (Internet), 15, p.1786_1 - 1786_10, 2024/02
Times Cited Count:0 Percentile:0.00Injecting high-energy heavy ions in the electronic stopping regime into solids can create cylindrical damage zones called latent ion tracks. Although these tracks form in many materials, none have ever been observed in diamond, even when irradiated with high-energy GeV uranium ions. Here we report the first observation of ion track formation in diamond irradiated with 2-9 MeV C fullerene ions. Depending on the ion energy, the mean track length (diameter) changed from 17 (3.2) nm to 52 (7.1) nm. High resolution scanning transmission electron microscopy (HR-STEM) indicated the amorphization in the tracks, in which -bonding signal from graphite was detected by the electron energy loss spectroscopy (EELS).
Okazaki, Hiroyuki*; Idesaki, Akira*; Koshikawa, Hiroshi*; Matsumura, Daiju; Ikeda, Takashi*; Yamamoto, Shunya*; Yamaki, Tetsuya*
Journal of Physical Chemistry C, 127(49), p.23628 - 23633, 2023/12
Times Cited Count:0 Percentile:0.00(Chemistry, Physical)Shibata, Motoki*; Nakanishi, Yohei*; Abe, Jun*; Arima, Hiroshi*; Iwase, Hiroki*; Shibayama, Mitsuhiro*; Motokawa, Ryuhei; Kumada, Takayuki; Takata, Shinichi; Yamamoto, Katsuhiro*; et al.
Polymer Journal, 55(11), p.1165 - 1170, 2023/11
Times Cited Count:1 Percentile:39.87(Polymer Science)Kawasaki, Ikuto; Takeuchi, Kazuharu*; Fujimori, Shinichi; Takeda, Yukiharu; Yamagami, Hiroshi; Yamamoto, Etsuji; Haga, Yoshinori
Physical Review B, 108(16), p.165127_1 - 165127_9, 2023/10
Takeda, Yukiharu; Pospil, J.*; Yamagami, Hiroshi; Yamamoto, Etsuji; Haga, Yoshinori
Physical Review B, 108(8), p.085129_1 - 085129_10, 2023/08
Times Cited Count:0 Percentile:0.00(Materials Science, Multidisciplinary)Nakagawa, Hiroshi; Yamamoto, Naoki*
Life (Internet), 13(2), p.318_1 - 318_15, 2023/02
Times Cited Count:1 Percentile:32.25(Biology)Incoherent neutron scattering and terahertz spectroscopy have approximately the same energy range of measurement. Since both techniques are used to study the dynamics of proteins and hydrated water, it is important to review the advantages and disadvantages of both techniques and the relevant literature. To the best of our knowledge, there is no review of both methods, and we believe that this review is of high value.
Tomotsune, Yusuke; Yajima, Mayumi; Okuno, Hiroshi; Yamamoto, Kazuya
Rodo Anzen Eisei Kenkyu, 16(1), p.29 - 43, 2023/02
During the first year of the accident at the Fukushima Daiichi Nuclear Power Station caused by the Great East Japan Earthquake in March 2011, a total of about 45,000 employees of Japan Atomic Energy Agency (JAEA) left their original workplaces to engage in telephone counseling, assistance of temporary return, and environmental monitoring. In particular, the staff who worked on the telephone counseling service, which directly contacted the residents, suffered from the stress associated with emotional labor. Systematic mental health care to the staff who engaged in these tasks was provided them in the Nuclear Fuel Cycle Engineering Laboratories of the JAEA. This paper considers this activity as a concrete example of "support for supporters" and discusses the mental health of the staff who provide support to the residents in a nuclear disaster.
Iwamoto, Osamu; Iwamoto, Nobuyuki; Kunieda, Satoshi; Minato, Futoshi; Nakayama, Shinsuke; Abe, Yutaka*; Tsubakihara, Kosuke*; Okumura, Shin*; Ishizuka, Chikako*; Yoshida, Tadashi*; et al.
Journal of Nuclear Science and Technology, 60(1), p.1 - 60, 2023/01
Times Cited Count:75 Percentile:99.99(Nuclear Science & Technology)Shimokita, Keisuke*; Yamamoto, Katsuhiro*; Miyata, Noboru*; Arima-Osonoi, Hiroshi*; Nakanishi, Yohei*; Takenaka, Mikihito*; Shibata, Motoki*; Yamada, Norifumi*; Seto, Hideki*; Aoki, Hiroyuki; et al.
Langmuir, 38(41), p.12457 - 12465, 2022/10
Times Cited Count:0 Percentile:0.00(Chemistry, Multidisciplinary)Yamamoto, Shingo*; Fujii, Takuto*; Luther, S.*; Yasuoka, Hiroshi*; Sakai, Hironori; Brtl, F.*; Ranjith, K. M.*; Rosner, H.*; Wosnitza, J.*; Strydom, A. M.*; et al.
Physical Review B, 106(11), p.115125_1 - 115125_5, 2022/09
Times Cited Count:0 Percentile:0.00(Materials Science, Multidisciplinary)We have studied the microscopic magnetic properties, the nature of the 130 K phase transition, and the ground state in the recently synthesized compound CeRhGa by use of Ga nuclear quadrupole resonance (NQR). The NQR spectra clearly show an unusual phase transition at K, yielding a splitting of the high-temperature single NQR line into two well-resolved NQR lines, providing evidence for two crystallographically inequivalent Ga sites. The NQR frequencies are in good agreement with fully relativistic calculations of the band structure. Our NQR results indicate the absence of magnetic or charge order down to 0.3 K. The temperature dependence of the spin-lattice relaxation rate shows three distinct regimes, with onset temperatures at and 2 K. The temperature-independent , observed between and 2 K, crosses over to a Korringa process, , below 2 K, which evidences a rare two-ion Kondo scenario: The system evolves into a dense Kondo coherent state below 2.0 and 0.8 K probed by the two different Ga sites.
Ohshima, Hiroyuki; Morishita, Masaki*; Aizawa, Kosuke; Ando, Masanori; Ashida, Takashi; Chikazawa, Yoshitaka; Doda, Norihiro; Enuma, Yasuhiro; Ezure, Toshiki; Fukano, Yoshitaka; et al.
Sodium-cooled Fast Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.3, 631 Pages, 2022/07
This book is a collection of the past experience of design, construction, and operation of two reactors, the latest knowledge and technology for SFR designs, and the future prospects of SFR development in Japan. It is intended to provide the perspective and the relevant knowledge to enable readers to become more familiar with SFR technology.
Tang, J.*; Seo, O.*; Rivera Rocabado, D. S.*; Koitaya, Takanori*; Yamamoto, Susumu*; Namba, Yusuke*; Song, C.*; Kim, J.*; Yoshigoe, Akitaka; Koyama, Michihisa*; et al.
Applied Surface Science, 587, p.152797_1 - 152797_8, 2022/06
Times Cited Count:7 Percentile:73.94(Chemistry, Physical)The hydrogen absorption and diffusion mechanisms on cube-shaped Pd nanoparticles (NPs) which are important hydrogen-storage materials were studied using X-ray photoelectron spectroscopy and DFT calculations. In the surface region, hydrogen absorption showed almost similar behavior regardless of the NPs size. It was found that the octahedral sites are more favorable than the tetrahedral sites for hydrogen occupation. We also clarified that the hydrogen atoms absorbing on the smaller-sized Pd NPs diffuse to the subsurface more actively because of the weakened Pd-H bond by the surface disordering, which plays an important role in hydrogen adsorption at a low H pressure.
Fujimori, Shinichi; Takeda, Yukiharu; Yamagami, Hiroshi; Pospil, J.*; Yamamoto, Etsuji; Haga, Yoshinori
Physical Review B, 105(11), p.115128_1 - 115128_6, 2022/03
Times Cited Count:0 Percentile:0.00(Materials Science, Multidisciplinary)Yamamoto, Naoki*; Nakanishi, Masahiro*; Rajan, R.*; Nakagawa, Hiroshi
Biophysics and Physicobiology (Internet), 18, p.284 - 288, 2021/12
Water is an indispensable solvent for living things. 60% of our body is composed of water, the lack of which causes lots of fatal problems. It has also been known that protein function is performed only when it accompanies water molecules around the surface, i.e. hydration water molecules. Therefore, it is essential to understand how water and biological component interact with each other in the view point of structure and dynamics. Freezing is a fundamental and simple phenomenon of water, and thus can be used as a probe for the purpose. Furthermore, preservation of cells and proteins under low temperature is crucial for numerous applications, which in turn triggers a myriad of undesirable consequences because of the freezing.
Fujimori, Shinichi; Takeda, Yukiharu; Yamagami, Hiroshi; Yamamoto, Etsuji; Haga, Yoshinori
Electronic Structure (Internet), 3(2), p.024008_1 - 024008_8, 2021/06
Okuno, Hiroshi; Sato, Sohei; Kawakami, Takeshi; Yamamoto, Kazuya; Tanaka, Tadao
Journal of Radiation Protection and Research, 46(2), p.66 - 79, 2021/06
The nuclear accident at the Fukushima Daiichi Nuclear Power Station (NPS) of Tokyo Electric Power Company (TEPCO) was a typical one of the disastrous damages that induced evacuation of the residents around the NPS, which was triggered by the hugest earthquake and associated tsunami. This paper summarized early responses of the Japan Atomic Energy Agency (JAEA), especially of its Nuclear Emergency Assistance and Training Center (NEAT) to the off-site emergencies associated with the TEPCO's Fukushima Daiichi NPS. The paper addressed activities of emergency preparedness of the NEAT before 2011 in relevant to the TEPCO's Fukushima Daiichi NPS, the situation of the NEAT on March 11, 2011, and its early responses to the related off-site emergencies including those caused by the accident at the TEPCO's Fukushima Daiichi NPS. The paper also discussed issues associated with complex disasters.
Yamamoto, Naoki*; Kofu, Maiko; Nakajima, Kenji; Nakagawa, Hiroshi; Shibayama, Naoya*
Journal of Physical Chemistry Letters (Internet), 12(8), p.2172 - 2176, 2021/03
Times Cited Count:9 Percentile:66.28(Chemistry, Physical)Hydration water plays a crucial role for activating the protein dynamics required for functional expression. Yet, the details are not understood about how hydration water couples with protein dynamics. A temperature hysteresis of the ice formation of hydration water is a key phenomenon to understand which type of hydration water, unfreezable or freezable hydration water, is crucial for the activation of protein dynamics. Using neutron scattering, we observed a temperature-hysteresis phenomenon in the diffraction peaks of the ice of freezable hydration water, whereas protein dynamics did not show any temperature hysteresis. These results show that the protein dynamics is not coupled with freezable hydration water dynamics, and unfreezable hydration water is essential for the activation of protein dynamics.
Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.
Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03
Times Cited Count:44 Percentile:96.99(Astronomy & Astrophysics)Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.
Okuno, Hiroshi; Yamamoto, Kazuya
JAEA-Review 2020-066, 32 Pages, 2021/02
The International Atomic Energy Agency (abbreviated as IAEA) has been implementing the Asian Nuclear Safety Network (abbreviated as ANSN) activities since 2002. As part of this effort, Topical Group on Emergency Preparedness and Response (abbreviated as EPRTG) for nuclear or radiation disasters was established in 2006 under the umbrella of the ANSN. Based on the EPRTG proposal, the IAEA conducted 23 Asian regional workshops in the 12 years from 2006 to 2017. Typical topical fields of the regional workshops were nuclear emergency drills, emergency medical care, long-term response after nuclear/radiological emergency, international cooperation, national nuclear disaster prevention system. The Japan Atomic Energy Agency has produced coordinators for EPRTG since its establishment and has led its activities since then. This report summarizes the Asian regional workshops conducted by the IAEA based on the recommendations of the EPRTG.
Amekura, Hiroshi*; Toulemonde, M.*; Narumi, Kazumasa*; Li, R.*; Chiba, Atsuya*; Hirano, Yoshimi*; Yamada, Keisuke*; Yamamoto, Shunya*; Ishikawa, Norito; Okubo, Nariaki; et al.
Scientific Reports (Internet), 11(1), p.185_1 - 185_11, 2021/01
Times Cited Count:13 Percentile:75.47(Multidisciplinary Sciences)We report the track formation of 10 nm in diameter in silicon irradiated with 6 MeV C, i.e., much lower energy than the previously reported energy threshold.