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Iyota, Muneyoshi*; Matsuda, Tomoki*; Sano, Tomokazu*; Shigeta, Masaya*; Shobu, Takahisa; Yumoto, Hirokatsu*; Koyama, Takahisa*; Yamazaki, Hiroshi*; Semba, Yasunori*; Ohashi, Haruhiko*; et al.
Journal of Manufacturing Processes, 94, p.424 - 434, 2023/05
Times Cited Count：3 Percentile：83.33(Engineering, Manufacturing)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：97.1(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.
Watanabe, Tamaki*; Toyama, Takeshi*; Hanamura, Kotoku*; Imao, Hiroshi*; Kamigaito, Osamu*; Kamoshida, Atsushi*; Kawachi, Toshihiko*; Koyama, Ryo*; Sakamoto, Naruhiko*; Fukunishi, Nobuhisa*; et al.
Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1105 - 1108, 2019/07
Upgrades for the RIKEN heavy-ion linac (RILAC) involving a new superconducting linac (SRILAC) are currently underway at the RIKEN radioactive isotope beam factory (RIBF). It is crucially important to develop nondestructive beam measurement diagnostics. We have developed a beam energy position monitor (BEPM) system which can measure not only the beam position but also the beam energy simultaneously by measuring the time of flight of the beam. We fabricated 11 BEPMs and completed the position calibration to obtain the sensitivity and offset for each BEPMs. The position accuracy has been achieved to be less than 
0.1 mm by using the mapping measurement.
Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; Matsuoka, Moe*; et al.
Science, 364(6437), p.272 - 275, 2019/04
Times Cited Count：262 Percentile：99.73(Multidisciplinary Sciences)The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is believed to be a primitive carbonaceous object. The Near Infrared Spectrometer (NIRS3) on Hayabusa2 acquired reflectance spectra of Ryugu's surface to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micron was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.
Watanabe, Tamaki*; Imao, Hiroshi*; Kamigaito, Osamu*; Sakamoto, Naruhiko*; Fukunishi, Nobuhisa*; Fujimaki, Masaki*; Yamada, Kazunari*; Watanabe, Yutaka*; Koyama, Ryo*; Toyama, Takeshi*; et al.
Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.49 - 54, 2018/08
no abstracts in English
Fujita, Shunya*; Abe, Yutaka*; Kaneko, Akiko*; Chonan, Fuminori*; Yuasa, Tomohisa*; Yamaki, Tatsunori*; Segawa, Tomoomi; Yamada, Yoshikazu
Proceedings of 25th International Conference on Nuclear Engineering (ICONE-25) (CD-ROM), 8 Pages, 2017/07
From the observation results, in the process of flushing, the behaviors leading to flushing were classified divided into three types. First type is that first generation bubble from heating leads to flushing. Second type is that nucleate boiling continues during heating and stop, finally single bubble generates and leads to flushing. Third type is defined that gradual evaporation occurs without bubbles. It was revealed that the total quantities of heat released by flushing are approximately equal when assuming the flushing mechanism, it can be triggered that a large amount of micro bubbles are instantaneously generated and grew.
Li + 
Pb reactionNishinaka, Ichiro; Yokoyama, Akihiko*; Washiyama, Koshin*; Maeda, Eita*; Watanabe, Shigeki; Hashimoto, Kazuyuki; Ishioka, Noriko; Makii, Hiroyuki; Toyoshima, Atsushi; Yamada, Norihiro*; et al.
Journal of Radioanalytical and Nuclear Chemistry, 304(3), p.1077 - 1083, 2015/06
Times Cited Count：9 Percentile：60.27(Chemistry, Analytical)Production cross sections of astatine isotopes 
At in the 29-57 MeV Li induced reaction with Pb target have been measured by 
- and 
-ray spectrometry. Excitation functions of production cross sections have been compared with a statistical model calculation to study the reaction mechanism of Li + Pb. Considerably small experimental cross sections of 
At and 
At compared with the calculation were clearly observed at incident energies higher than 44 MeV, indicating that the effects of breakup reaction play a role. A chemical separation of astatine from an irradiated lead target has been studied with a dry-distillation method. A complementary way to produce astatine isotopes has been developed.
Unno, Masayoshi*; Ishikawa, Kumiko*; Kusaka, Katsuhiro*; Tamada, Taro; Hagiwara, Yoshinori*; Sugishima, Masakazu*; Wada, Kei*; Yamada, Taro*; Tomoyori, Katsuaki; Hosoya, Takaaki*; et al.
Journal of the American Chemical Society, 137(16), p.5452 - 5460, 2015/04
Times Cited Count：28 Percentile：64.15(Chemistry, Multidisciplinary)Phycocyanobilin, a light-harvesting and photoreceptor pigment in higher plants, algae, and cyanobacteria, is synthesized from biliverdin IX (BV) by phycocyanobilin:ferredoxin oxidoreductase (PcyA) via two steps of two-proton-coupled two-electron reduction. We determined the neutron structure of PcyA from cyanobacteria complexed with BV, revealing the exact location of the hydrogen atoms involved in catalysis. Notably, approximately half of the BV bound to PcyA was BVH
, a state in which all four pyrrole nitrogen atoms were protonated. The protonation states of BV complemented the protonation of adjacent Asp105. The "axial "water molecule that interacts with the neutral pyrrole nitrogen of the A-ring was identified. His88 N
was protonated to form a hydrogen bond with the lactam O atom of the BV A-ring. His88 and His74 were linked by hydrogen bonds via H
O. These results imply that Asp105, His88, and the axial water molecule contribute to proton transfer during PcyA catalysis.
Yamaki, Tatsunori*; Abe, Yutaka*; Kaneko, Akiko*; Segawa, Tomoomi; Kawaguchi, Koichi; Yamada, Yoshikazu; Fujii, Kanichi*
Journal of Nuclear Science and Technology, 52(2), p.241 - 250, 2015/02
Times Cited Count：3 Percentile：25.64(Nuclear Science & Technology)In the Microwave Heating de-nitration method developed in Japan, a mixed solution of uranyl nitrate and plutonium nitrate recovered from the spent fuel in the reprocessing plant is converted directly to mixed oxide (MH-MOX) powder. This MH-MOX powder is utilized to fabricate MOX fuel with UO
powder for FBR. The MH method is accompanied with transient boiling phenomena such as overflow and flushing. Toward high-speed and high-capacity conversion by MH-method in the future, it is required to avoid overflow and flushing and to understand optimal design conditions for design and operation. At the first step for these objectives, basic knowledge of transient boiling phenomena by the MH-method has been acquired with using distilled water. It was observed that generation of singular bubble triggered flushing and distilled water just before flushing was superheated by a temperature 10 degrees centigrade higher than boiling temperature. Based on these results, it is clarified that the occurrence criteria of flushing correlate with absorbed power in the water and released power from the water surface.
Yamaki, Tatsunori*; Abe, Yutaka*; Kaneko, Akiko*; Segawa, Tomoomi; Kawaguchi, Koichi; Yamada, Yoshikazu
Proceedings of the 22nd International Conference on Nuclear Engineering 2014 (ICONE-22), Vol.2A, p.V02AT09A011_1 - V02AT09A011_10, 2014/07
Uranium and plutonium mixed nitrate solution of the spent nuclear fuel is converted to uranium and plutonium mixed oxide (MOX) powder by the microwave heating direct denitration method in co-conversion process of the nuclear fuel cycle. The cylindrical denitration vessel can be expected to realize high-speed and high-capacity processing against traditional shallow vessel. However, flushing and overflow phenomena of solution have been confirmed in cylindrical vessel. Thus, It is required to be clarified that the generation condition and generation mechanism of flushing phenomena during microwave heating for the safety of the operating condition and the optimum design of the equipment. The craiteria of flushing phenomena and the relationship between the released power by evaporation and the absorbed power in water is confirmed by the experimental results from the microwave heating. It is found that the flow structure is changed and the outer surface is heated according to the increase of the concentration of KCl by the microwave heating experiment with using the KCl solution and KCl jelly as a simulated solution of the uranium and plutonium mixed nitrate solution.
Kondo, Hiroaki*; Yamada, Tetsuji*; Chino, Masamichi; Iwasaki, Toshiki*; Katata, Genki; Maki, Takashi*; Saito, Kazuo*; Terada, Hiroaki; Tsuruta, Haruo*
Tenki, 60(9), p.723 - 729, 2013/09
no abstracts in English
Nakasone, Akari*; Fujiwara, Masayuki*; Fukao, Yoichiro*; Biswas, K.; Rahman, A.*; Yamada, Maki*; Narumi, Issei; Uchimiya, Hirofumi*; Ono, Yutaka
Plant Physiology, 160(1), p.93 - 105, 2012/09
Times Cited Count：12 Percentile：38.47(Plant Sciences)-ray pre-irradiation graftingKoshikawa, Hiroshi; Yamaki, Tetsuya; Asano, Masaharu; Maekawa, Yasunari; Yamaguchi, Susumu*; Yamamoto, Kazuya*; Asazawa, Koichiro*; Yamada, Koji*; Tanaka, Hirohisa*
Proceedings of 12th International Conference on Radiation Curing in Asia (RadTech Asia 2011) (Internet), p.240 - 241, 2011/06
The anion-exchange membranes (AEM) for fuel cells were prepared by the radiation-induced graft polymerization of chloromethylstyrene into poly(ethylene-co-tetrafluoroethylene) (ETFE) films and subsequent quaternization of the grafts with trimethylamine. When the AEM were treated in 1M-KOH and washed with N-saturated water, the membranes with chloride form can be converted quantitatively to hydroxide form. However, the hydroxide form was easily converted to the bicarbonate form by the treatment in non-bubbled (CO dissolved) water. When we introduced the crosslinkers in polymer grafts, which is proved to be very effective in the proton conducting PEM having a poly(styrenesulfonic acid) grafts, the grafted AEM with both chloride and hydroxide forms showed only slight decrease of water uptake. It should be noted that AEM with hydroxide form showed very high tendency to absorb water.
potentially mediates the response to synthetic auxin, 2,4-dichlorophenoxyacetic acid, in 
Nakasone, Akari; Yamada, Maki*; Kiyosue, Tomohiro*; Narumi, Issei; Uchimiya, Hirofumi*; Ono, Yutaka
Journal of Plant Physiology, 166(12), p.1307 - 1313, 2009/08
Times Cited Count：4 Percentile：13.01(Plant Sciences)Tsuchiya, Kunihiko; Hoshino, Tsuyoshi; Kawamura, Hiroshi; Mishima, Yoshinao*; Yoshida, Naoaki*; Terai, Takayuki*; Tanaka, Satoru*; Munakata, Kenzo*; Kato, Shigeru*; Uchida, Munenori*; et al.
Nuclear Fusion, 47(9), p.1300 - 1306, 2007/09
Times Cited Count：23 Percentile：61.91(Physics, Fluids & Plasmas)no abstracts in English
Sm(,n) cross section with laser-Compton scattering rays and the photon difference methodHara, Kaoru; Harada, Hideo; Kitatani, Fumito; Goko, Shinji*; Hohara, Shinya*; Kaihori, Takeshi*; Makinaga, Ayano*; Utsunomiya, Hiroaki*; Toyokawa, Hiroyuki*; Yamada, Kawakatsu*
Journal of Nuclear Science and Technology, 44(7), p.938 - 945, 2007/07
Times Cited Count：40 Percentile：91.81(Nuclear Science & Technology)no abstracts in English
Tsuchiya, Kunihiko; Hoshino, Tsuyoshi; Kawamura, Hiroshi; Mishima, Yoshinao*; Yoshida, Naoaki*; Terai, Takayuki*; Tanaka, Satoru*; Munakata, Kenzo*; Kato, Shigeru*; Uchida, Munenori*; et al.
Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2007/03
no abstracts in English
SmHara, Kaoru; Harada, Hideo; Kitatani, Fumito; Goko, Shinji*; Hohara, Shinya*; Kaihori, Takeshi*; Makinaga, Ayano*; Utsunomiya, Hiroaki*; Toyokawa, Hiroyuki*; Yamada, Kawakatsu*; et al.
EUR-22794-EN, p.65 - 68, 2007/00
Neutron capture cross sections of the unstable nuclei 
Sm (t
=90yr) are the fundamental data for the nuclear transmutation, since the Sm is one of radioactive fission products in the nuclear waste. On the other hand, the branching point nucleus Sm is important for characterizing the slow neutron capture process (s-process) nucleosynthesis in the AGB stars. The cross sections of the inverse Sm(,n)Sm reaction were measured with the laser-Compton scattering (LCS) rays at 8.3-12.4 MeV. Quasi-monochromatic beams of LCS photons irradiated an enriched Sm
O
sample. The emitted neutrons were detected with a 4
neutron detector consisting of 20 
He proportional counters embedded in a polyethylene moderator. The 
Au(,n) reaction cross sections were also measured as a standard. In the data analysis, the (,n) cross sections are deduced with two methods. The present data for Sm and Au are compared with the previous data compiled in the IAEA document and the calculation with a nuclear reaction code TALYS. The neutron capture cross sections for Sm in the keV-MeV energy range are evaluated with the present photonuclear data for Sm as constraint in the statistical model calculations.
TiO pebble bed under neutron pulse operationTsuchiya, Kunihiko; Kikukawa, Akihiro*; Hoshino, Tsuyoshi; Nakamichi, Masaru; Yamada, Hirokazu*; Yamaki, Daiju; Enoeda, Mikio; Ishitsuka, Etsuo; Kawamura, Hiroshi; Ito, Haruhiko; et al.
Journal of Nuclear Materials, 329-333(Part2), p.1248 - 1251, 2004/08
Times Cited Count：10 Percentile：55.63(Materials Science, Multidisciplinary)no abstracts in English
Kambara, Toyozo; Uno, Hidero; Shoda, Katsuhiko; Hirata, Yutaka; Shoji, Tsutomu; Kohayakawa, Toru; Takayanagi, Hiroshi; Fujimura, Tsutomu; Morita, Morito; Ichihara, Masahiro; et al.
JAERI 1045, 11 Pages, 1963/03
no abstracts in English
