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Journal Articles

Radiocesium distribution in the sediments of the Odaka River estuary, Fukushima, Japan

Hagiwara, Hiroki; Nakanishi, Takahiro; Konishi, Hiromi*; Tsuruta, Tadahiko; Misono, Toshiharu; Fujiwara, Kenso; Kitamura, Akihiro

Journal of Environmental Radioactivity, 220-221, p.106294_1 - 106294_9, 2020/09

 Times Cited Count:0 Percentile:100(Environmental Sciences)

Journal Articles

Mineral composition characteristics of radiocesium sorbed and transported sediments within the Tomioka river basin in Fukushima Prefecture

Hagiwara, Hiroki; Konishi, Hiromi*; Nakanishi, Takahiro; Fujiwara, Kenso; Iijima, Kazuki; Kitamura, Akihiro

Journal of Environmental Radioactivity, 211, p.106042_1 - 106042_10, 2020/01

 Times Cited Count:1 Percentile:100(Environmental Sciences)

Journal Articles

Sensitivity of charged particle activation analysis for long-lived radioactive nuclide determination

Oshima, Masumi*; Yamaguchi, Yurie*; Asai, Masato; Tsukada, Kazuaki; Goto, Jun*; Bamba, Shigeru*; Bi, C.*; Morimoto, Takao*

Journal of Nuclear Science and Technology, 56(9-10), p.866 - 872, 2019/09

 Times Cited Count:1 Percentile:58.8(Nuclear Science & Technology)

Sensitivity of charged particle activation analysis with 8 MeV proton beam was studied for determination of 35 long-lived radioactive nuclides. Reaction cross sections for those nuclides were estimated with ALICE-91 code and isomer yield ratios were estimated from those of neighboring isotopes by taking into account their spins and parities. It was found that the proposed charged particle activation analysis should show high sensitivity for the determination of several hardly measurable nuclides with long half-lives such as $$^{135}$$Cs, $$^{244}$$Pu, $$^{129}$$I, $$^{126}$$Sn, $$^{93}$$Mo, $$^{107}$$Pd, $$^{236}$$U, $$^{248}$$Cm, and $$^{237}$$Np.

Journal Articles

Dynamic nuclear self-polarization of III-V semiconductors

Koizumi, Mitsuo; Goto, Jun*; Matsuki, Seishi*

Journal of Semiconductors, 39(8), p.082001_1 - 082001_5, 2018/08

Dynamic nuclear self-polarization (DYNASP) is a phenomenon observed in III-V semiconductors. When electrons of the valence band of a semiconductor are optically excited to the conduction band, a relaxation process of the conduction electrons induces a large nuclear polarization to suddenly occur below a critical temperature. Extending the original theoretical work of Dyakonov et al., we examined the effect of spin distribution of valence electrons excited by the circularly polarized light and the effect of external magnetic field on the phenomenon of the nuclear self-polarization. We found that the nuclear polarization is achieved even above the critical temperatures by the effect of electron polarization and of the external magnetic field. To investigate the phenomenon experimentally, we constructed an apparatus for low-temperature experiments.

Journal Articles

Production of $$^{13}$$N-labeled nitrogen gas tracer for the imaging of nitrogen fixation in soybean nodules

Ishii, Satomi; Igura, Masato*; Yin, Y.-G.; Hung, N. V. P.*; Suzui, Nobuo; Kawachi, Naoki; Koyanagi, Atsushi*; Oyama, Takuji*; Fujimaki, Shu

JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 98, 2014/03

Journal Articles

Analysis of the effect of O$$_{2}$$ partial pressure on nitrogen fixation in soybean plant using positron-emitting tracer

Hung, N. V. P.; Ishii, Satomi; Suzui, Nobuo; Kawachi, Naoki; Yin, Y.-G.; Koyanagi, Atsushi; Oyama, Takuji*; Fujimaki, Shu

JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 99, 2014/03

The impacts of oxygen in rhizosphere on the symbiotic nitrogen fixation in real-time was evaluated under various O$$_{2}$$ partial pressure. Soybean nodules were treated with mixed gas containing N$$_{2}$$ labeled with a radioisotope $$^{13}$$N and various concentrations of O$$_{2}$$, and the nitrogen fixation activity in the nodules was visualized by the positron-emitting tracer imaging system (PETIS). The results showed that under normal condition the nitrogen fixation ability of soybean plant was higher compared to that of under the other conditions (0% O$$_{2}$$ and 10% O$$_{2}$$). There was no significant difference in the nitrogen fixation activity between 0% O$$_{2}$$ and 10% O$$_{2}$$.

Journal Articles

Dynamic nuclear self-polarization for measurements of nuclear magnetic moments

Koizumi, Mitsuo; Goto, Jun*; Matsuki, Seishi*; Nakamura, Shoji

Nuclear Instruments and Methods in Physics Research B, 317(Part B), p.689 - 692, 2013/12

 Times Cited Count:1 Percentile:86.68(Instruments & Instrumentation)

Dynamic nuclear self-polarization (DYNASP) is a phenomenon that is observed in the III-V semiconductors. When electrons in the valence band of a semiconductor are optically excited to the conduction band, quite large nuclear polarization suddenly occurs below a critical temperature. This phenomenon was theoretically predicted by Dyakonov and Perel. Our recent work predicted that the electrons excited by circularly polarized laser enhance nuclear polarization near the critical temperature. The mechanism of such a large nuclear polarization would be useful for measurements of nuclear magnetic moments of unstable nuclides. However, the experiment on DYNASP can be found only in a conference report. In order to confirm the phenomenon, we have started the study of DYNASP. Preparation of experiments on DYNASP is in progress. In this paper, we describe the present status of the study of nuclear polarization by using DYNASP from the theoretical and experimental aspects.

Journal Articles

Quantitative analysis of the initial transport of fixed nitrogen in nodulated soybean plants using $$^{15}$$N as a tracer

Hung, N. V. P.*; Watanabe, Shiori*; Ishikawa, Shinji*; Otake, Norikuni*; Sueyoshi, Kuni*; Sato, Takashi*; Ishii, Satomi; Fujimaki, Shu; Oyama, Takuji*

Soil Science and Plant Nutrition, 59(6), p.888 - 895, 2013/12

 Times Cited Count:4 Percentile:79.38(Plant Sciences)

Journal Articles

Excitation functions for production of Rf isotopes in the $$^{248}$$Cm + $$^{18}$$O reaction

Murakami, Masashi*; Goto, Shinichi*; Murayama, Hirofumi*; Kojima, Takayuki*; Kudo, Hisaaki*; Kaji, Daiya*; Morimoto, Koji*; Haba, Hiromitsu*; Kudo, Yuki*; Sumita, Takayuki*; et al.

Physical Review C, 88(2), p.024618_1 - 024618_8, 2013/08

 Times Cited Count:11 Percentile:33.76(Physics, Nuclear)

Production cross sections of Rf isotopes in the $$^{248}$$Cm + $$^{18}$$O reaction were measured at the beam energy range of 88.2 to 101.3 MeV by use of a gas-filled recoil ion separator. The excitation functions of $$^{260}$$Rf, $$^{261a}$$Rf, and $$^{262}$$Rf were obtained together with those of spontaneously fissioning nuclides which have few-second half-lives and have been assigned to $$^{261b}$$Rf and a longer-lived state of $$^{262}$$Rf. The excitation function of few-second spontaneously fissioning nuclide exhibited the maximum cross section at the $$^{18}$$O beam energy of 94.8 MeV. The shape of the excitation function was almost the same as that of $$^{261a}$$Rf, whereas it was quite different from those of $$^{260}$$Rf and $$^{262}$$Rf. A few-second spontaneously fissioning nuclide previously reported as $$^{261b}$$Rf and $$^{262}$$Rf observed in$$^{248}$$Cm + $$^{18}$$O reaction was identified as $$^{261b}$$Rf.

Journal Articles

Effect of nitrate on nodulation and nitrogen fixation of soybean

Oyama, Takuji; Fujikake, Hiroyuki*; Yashima, Hiroyuki*; Tanabata, Sayuri*; Ishikawa, Shinji*; Sato, Takashi*; Nishiwaki, Toshikazu*; Otake, Norikuni*; Sueyoshi, Kuni*; Ishii, Satomi; et al.

Soybean Physiology and Biochemistry, p.333 - 364, 2011/11

no abstracts in English

Journal Articles

Fluorido complex formation of element 104, rutherfordium (Rf)

Ishii, Yasuo; Toyoshima, Atsushi; Tsukada, Kazuaki; Asai, Masato; Li, Z.*; Nagame, Yuichiro; Miyashita, Sunao*; Mori, Tomotaka*; Suganuma, Hideo*; Haba, Hiromitsu*; et al.

Bulletin of the Chemical Society of Japan, 84(9), p.903 - 911, 2011/09

 Times Cited Count:14 Percentile:50.57(Chemistry, Multidisciplinary)

The cation-exchange behavior of element 104, rutherfordium (Rf), was investigated together with its lighter group-4 homologues Zr and Hf, and the tetravalent pseudo-homologue Th in HF/HNO$$_{3}$$ mixed solution. The results demonstrate that distribution coefficients ($$K_{d}$$) of Rf in HF/0.10 M HNO$$_{3}$$ decrease with increasing concentration of the fluoride ion [F$$^{-}$$], indicating the consecutive formation of fluorido complexes of Rf. We also measured the $$K_{d}$$ values of Rf and the homologues as a function of the hydrogen ion concentration [H$$^{+}$$]. The log $$K_{d}$$ values decrease linearly with an increase of log [H$$^{+}$$] with slopes between -2.1 and -2.5. This indicates that these elements are likely to form the same chemical compounds: mixture of [MF]$$^{3+}$$ and [MF$$_{2}$$]$$^{2+}$$ (M = Rf, Zr, Hf and Th) in the studied solution. It is also ascertained that sequence in the fluoride complex formation is Zr $$sim$$ Hf $$>$$ Rf $$>$$ Th.

Journal Articles

Design of a 4$$pi$$ LaBr$$_{3}$$(Ce) spectrometer for neutron capture cross section measurements

Goto, Jun*; Harada, Hideo; Kitatani, Fumito; Nagai, Yasuki; Oshima, Masumi; Segawa, Mariko; Toh, Yosuke

Journal of the Korean Physical Society, 59(2), p.1585 - 1588, 2011/08

 Times Cited Count:2 Percentile:77.61(Physics, Multidisciplinary)

A 4$$pi$$ LaBr$$_{3}$$(Ce) spectrometer was designed for the measurements of neutron capture cross sections using a prompt $$gamma$$-ray spectroscopic method with a time-of-flight technique. An optimum configuration for the 4$$pi$$ LaBr$$_{3}$$(Ce) spectrometer was adopted from four possible configurations based on comparison of simulated performance and cost of construction. Further simulations were performed to demonstrate performance of the 4$$pi$$ LaBr$$_{3}$$(Ce) spectrometer.

Journal Articles

Dynamic nuclear self-polarization with circularly polarized light

Koizumi, Mitsuo; Goto, Jun*; Matsuki, Seishi*

Journal of Applied Physics, 110(1), p.013911_1 - 013911_8, 2011/07

 Times Cited Count:2 Percentile:88.61(Physics, Applied)

Lattice nuclei of III-V type semiconductors can be self-polarized through the contact hyperfine interaction with optically excited electrons on the conduction band at low temperatures. The effect of electrons excited with circularly polarized light is introduced to the theoretical prediction of self-polarization. We found that the degree of nuclear polarization is enhanced in comparison with the use of un-polarized light. The direction of the nuclear polarization is controlled by the orientation of the electron polarization. A hysteresis phenomenon appears in the nuclear polarization when varying the degree of electron polarization.

Journal Articles

Regulation of root nodule formation in leguminous plants

Ito, Sayuri; Fujimaki, Shu; Kato, Taichi*; Otake, Norikuni*; Sueyoshi, Kuni*; Oyama, Takuji*

Nitrogen assimilation in plants, p.205 - 214, 2010/07

Journal Articles

Extraction of chromatographic behavior of Rf, Zr, and Hf in HCl solution with styrenedivinylbenzene copolymer resin modified by TOPO (trioctylphosphine oxide)

Toyoshima, Atsushi; Kasamatsu, Yoshitaka*; Tsukada, Kazuaki; Asai, Masato; Ishii, Yasuo; Tome, Hayato*; Nishinaka, Ichiro; Sato, Tetsuya; Nagame, Yuichiro; Sch$"a$del, M.; et al.

Journal of Nuclear and Radiochemical Sciences, 11(1), p.7 - 11, 2010/06

The extraction behavior of rutherfordium (Rf) into trioctylphosphine oxide (TOPO) from 2.0 - 7.0 M HCl solution was studied together with that of the homologues Zr and Hf. The extracted yields of Rf, Zr, and Hf increased with an increase of HCl concentration, and the sequence of their extraction was Zr $$>$$ Hf $$geq$$ Rf. It is suggested that the stability of the RfCl$$_{4}$$$$cdot$$2(TOPO) complex is lower than that of the corresponding species of the homologues.

Journal Articles

Imaging of the nodule function in leguminous plants who utilize nitrogen gas in the air as nutrition

Fujimaki, Shu; Ishii, Satomi; Oyama, Takuji*

Hoshasen To Sangyo, (124), p.32 - 35, 2009/12

The nodule is a symbiotic organ developed on roots of leguminous plants which have been infected with rhizobia, a group of soil bacteria. The plants with nodules can obtain nitrogen nutrition as ammonia converted from nitrogen gas in the air by rhizobia in the nodules. This function, "symbiotic nitrogen fixation", plays a fundamental role in the food production in the world. Recently, we reported that we have successfully visualized the symbiotic nitrogen fixation in soybean plants non-invasively using a positron-emitting tracer imaging system (PETIS) and nitrogen-13-labelled nitrogen gas tracer. In this article, this study is described with the scientific and social backgrounds.

Journal Articles

The Production of $$^{13}$$N-labeled nitrogen gas tracer and the imaging of nitrogen fixation in soybean nodules

Ishii, Satomi; Suzui, Nobuo; Ito, Sayuri; Ishioka, Noriko; Kawachi, Naoki; Matsuhashi, Shimpei; Otake, Norikuni*; Oyama, Takuji*; Fujimaki, Shu

JAEA-Review 2009-041, JAEA Takasaki Annual Report 2008, P. 106, 2009/12

Journal Articles

Real-time imaging of nitrogen fixation in an intact soybean plant with nodules using $$^{13}$$N-labeled nitrogen gas

Ishii, Satomi; Suzui, Nobuo; Ito, Sayuri; Ishioka, Noriko; Kawachi, Naoki; Otake, Norikuni*; Oyama, Takuji*; Fujimaki, Shu

Soil Science and Plant Nutrition, 55(5), p.660 - 666, 2009/10

 Times Cited Count:10 Percentile:64.11(Plant Sciences)

Journal Articles

Adsorption of Db and its homologues Nb and Ta, and the pseudo-homologue Pa on anion-exchange resin in HF solution

Tsukada, Kazuaki; Haba, Hiromitsu*; Asai, Masato; Toyoshima, Atsushi; Akiyama, Kazuhiko*; Kasamatsu, Yoshitaka; Nishinaka, Ichiro; Ichikawa, Shinichi; Yasuda, Kenichiro; Miyamoto, Yutaka; et al.

Radiochimica Acta, 97(2), p.83 - 89, 2009/02

 Times Cited Count:20 Percentile:17.57(Chemistry, Inorganic & Nuclear)

Anion-exchange chromatography of element 105, dubnium (Db), produced in the $$^{248}$$Cm($$^{19}$$F, 5n)$$^{262}$$Db reaction is investigated together with the homologues Nb and Ta, and the pseudo-homologue Pa in 13.9 M hydrofluoric acid (HF) solution. The distribution coefficient (K$$_{d}$$) of Db on an anion-exchange resin is successfully determined by running cycles of the 1702 chromatographic column separations. The result clearly indicates that the adsorption of Db on the resin is significantly different from that of the homologues and that the adsorption of anionic fluoro complexes of these elements decreases in the sequence of Ta $$approx$$ Nb $$>$$ Db $$geq$$ Pa.

Journal Articles

The Production of $$^{13}$$N-labeled nitrogen gas for imaging of nitrogen fixation by soybean nodule

Ishii, Satomi; Suzui, Nobuo; Ishioka, Noriko; Kawachi, Naoki; Matsuhashi, Shimpei; Otake, Norikuni*; Oyama, Takuji*; Fujimaki, Shu

JAEA-Review 2008-055, JAEA Takasaki Annual Report 2007, P. 111, 2008/11

91 (Records 1-20 displayed on this page)