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Journal Articles

Thermally altered subsurface material of asteroid (162173) Ryugu

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:30 Percentile:96.42(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 $$^{circ}$$C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 $$^{circ}$$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.

Journal Articles

Role of filamentous fungi in migration of radioactive cesium in the Fukushima forest soil environment

Onuki, Toshihiko; Sakamoto, Fuminori; Kozai, Naofumi; Namba, Kenji*; Neda, Hitoshi*; Sasaki, Yoshito; Niizato, Tadafumi; Watanabe, Naoko*; Kozaki, Tamotsu*

Environmental Science; Processes & Impacts, 21(7), p.1164 - 1173, 2019/07

 Times Cited Count:10 Percentile:47.07(Chemistry, Analytical)

The fate of radioactive Cs deposited after the Fukushima nuclear power plant accident and its associated radiological impacts are largely dependent on its mobility from surface soils to forest ecosystems. We measured the accumulation of radioactive Cs in the fruit bodies of wild fungi in the forest at Iidate, Fukushima, Japan. The transfer factors (TFs) of radioactive Cs from soil to the fruit bodies of wild fungi were between 10 $$^{-2}$$to 10$$^{2}$$, a range similar to those reported for the fruit bodies collected in Europe after the Chernobyl accident and in parts of Japan contaminated by nuclear bomb test fallout. Comparison of the TFs of the wild mushroom and that of the fungal hyphae of 704 stock strains grown on agar medium containing nutrients and radioactive Cs showed that the TFs of wild mushroom were lower. TF was less than 0.1 after addition of the minerals zeolite, vermiculite, phlogopite, smectite, or illite of 1% weight to the agar medium. These results indicate that the presence of minerals decrease Cs uptake by fungi grown in the agar medium.

Journal Articles

The Surface composition of asteroid 162173 Ryugu from Hayabusa2 near-infrared spectroscopy

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:233 Percentile:99.75(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.

Journal Articles

Mineralogical control of the size distribution of stable Cs and radiocesium in riverbed sediments

Tanaka, Kazuya; Watanabe, Naoko*; Yamasaki, Shinya*; Sakaguchi, Aya*; Fan, Q.*; Takahashi, Yoshio*

Geochemical Journal, 52(2), p.173 - 185, 2018/00

 Times Cited Count:9 Percentile:45.19(Geochemistry & Geophysics)

We analyzed riverbed sediments collected at two sites, Yamakiya and Kuroiwa, in Fukushima after the Fukushima accident. The size distributions of K, Rb, and $$^{133}$$Csreflected the mineralogy of sediments, where primary host minerals for these alkali elements would be biotite, K-feldspar, and clay minerals. Silt-size fractions contained high $$^{133}$$Cs and $$^{137}$$Cs concentrations possibly due to adsorption on clay minerals. Their concentrations decreased with particle size at the Yamakiya site. In contrast, coarse and very coarse sand fractions from the Kuroiwa site showed higher $$^{133}$$Cs and $$^{137}$$Cs concentrations in comparison to fine - medium sand fractions. The coarse sand fractions contained many weathered biotite grains. Overall, the size distributions of $$^{133}$$Cs and $$^{137}$$Cs were similar in the sediments, suggesting that the Fukushima-derived radiocesium was distributed into each particle size fraction in response to the distribution of the stable Cs that was controlled by mineralogical composition.

Journal Articles

Ligand exchange adsorption and coordination structure of Pd on $$delta$$-MnO$$_{2}$$ in NaCl solution

Tanaka, Kazuya; Tanaka, Masato*; Watanabe, Naoko*; Tokunaga, Kohei*; Takahashi, Yoshio*

Chemical Geology, 460, p.130 - 137, 2017/06

 Times Cited Count:7 Percentile:31.94(Geochemistry & Geophysics)

Pd is highly accumulated in ferromanganese nodules and crusts relative to its concentration in seawater but the mechanism by which Pd(II) is incorporated remains poorly understood. We investigated the local coordination structure of Pd(II) adsorbed on $$delta$$-MnO$$_{2}$$, using X-ray absorption fine structure spectroscopy. X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analyses indicated that Pd was adsorbed on $$delta$$-MnO$$_{2}$$ through ligand exchange, from Cl coordination to O coordination. Furthermore, curve fitting of EXAFS spectra demonstrated the formation of two different inner-sphere complexes, bidentate-mononuclear and bidentate-binuclear complexes, and this finding was supported by density functional theory calculations. The formation of inner-sphere complexes is reasonable given the relatively large distribution coefficients obtained from adsorption experiments.

Journal Articles

Simultaneous recovery and separation of rare earth elements in ferromanganese nodules by using ${{it Shewanella putrefaciens}}$

Fujimoto, Jun*; Tanaka, Kazuya; Watanabe, Naoko*; Takahashi, Yoshio*

Hydrometallurgy, 166, p.80 - 86, 2016/12

 Times Cited Count:6 Percentile:32.43(Metallurgy & Metallurgical Engineering)

We examined recovery of REEs in Fe-Mn nodules by using ${{it Shewanella putrefaciens}}$ (Fe-reducing bacterium). In this method, Fe-Mn nodule decomposition and REE recovery were achieved simultaneously in a single solution system. Fe-Mn nodules were reductively decomposed in NaCl solution under anaerobic conditions with daily addition of sodium lactate as an electron donor. During the decomposition of Fe-Mn nodule, REEs released from the Fe-Mn nodule were adsorbed on bacterial cells. Of the conditions studied here, the best REE adsorption rates were obtained with 0.5M NaCl solution at pH7 with daily addition of 1 mmol sodium lactate.

Journal Articles

Root endophytic bacteria of a $$^{137}$$Cs and Mn accumulator plant, ${{it Eleutherococcus sciadophylloides}}$, increase $$^{137}$$Cs and Mn desorption in the soil

Yamaji, Keiko*; Nagata, Satoshi*; Haruma, Toshikatsu*; Onuki, Toshihiko; Kozaki, Tamotsu*; Watanabe, Naoko*; Namba, Kenji*

Journal of Environmental Radioactivity, 153, p.112 - 119, 2016/03

 Times Cited Count:19 Percentile:56.13(Environmental Sciences)

Of the 463 strains that we isolated, 107 (23.1%) produced the siderophores. We found $$^{137}$$Cs and Mn desorption concomitant with Al and Fe desorption. These results suggest that root endophytes of $$^{137}$$Cs accumulator plant produce siderophores, resulting in the desorption of $$^{137}$$Cs from the contaminated soil collected at Fukushima, Japan.

Journal Articles

Effect of minerals on accumulation of Cs by fungus ${{it Saccaromyces cerevisiae}}$

Onuki, Toshihiko; Sakamoto, Fuminori; Yamasaki, Shinya*; Kozai, Naofumi; Shiotsu, Hiroyuki; Utsunomiya, Satoshi*; Watanabe, Naoko*; Kozaki, Tamotsu*

Journal of Environmental Radioactivity, 144, p.127 - 133, 2015/06

 Times Cited Count:9 Percentile:27.95(Environmental Sciences)

The accumulation of Cs by unicellular fungus of ${{it Saccaromyces cerevisiae}}$ in the presence of minerals has been studied to elucidate the role of microorganisms in the migration of radioactive Cs in the environment. In the presence of minerals in the agar medium, the radioactivity in the yeast cells was in the order of mica $$>$$ smectite, illite $$>>$$ vermiculite, phlogopite, zeolite. This order is inversely correlated to the ratio of the concentration of radioactive Cs between the minerals and the medium solution. These results strongly suggest that the yeast accumulates radioactive Cs competitively with minerals.

Journal Articles

Dipole tracer migration and diffusion tests in fractured sedimentary rock at Horonobe URL

Tanaka, Shingo*; Yokota, Hideharu; Ono, Hirokazu; Nakayama, Masashi; Fujita, Tomoo; Takiya, Hiroaki*; Watanabe, Naoko*; Kozaki, Tamotsu*

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 6 Pages, 2015/05

Journal Articles

$$^{52}$$Fe translocation in barley as monitored by a Positron-Emitting Tracer Imaging System (PETIS); Evidence for the direct translocation of Fe from roots to young leaves via phloem

Tsukamoto, Takashi*; Nakanishi, Hiromi*; Uchida, Hiroshi*; Watanabe, Satoshi; Matsuhashi, Shimpei; Mori, Satoshi*; Nishizawa, Naoko*

Plant & Cell Physiology, 50(1), p.48 - 57, 2009/01

 Times Cited Count:85 Percentile:90.06(Plant Sciences)

Journal Articles

Report on ITPA meetings, 24

Idomura, Yasuhiro; Yoshida, Maiko; Yagi, Masatoshi*; Tanaka, Kenji*; Hayashi, Nobuhiko; Sakamoto, Yoshiteru; Tamura, Naoki*; Oyama, Naoyuki; Urano, Hajime; Aiba, Nobuyuki; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 84(12), p.952 - 955, 2008/12

no abstracts in English

Journal Articles

Deoxymugineic acid increases Zn translocation in Zn-deficient rice plants

Suzuki, Motofumi*; Tsukamoto, Takashi*; Inoue, Haruhiko*; Watanabe, Satoshi; Matsuhashi, Shimpei; Takahashi, Michiko*; Nakanishi, Hiromi*; Mori, Satoshi*; Nishizawa, Naoko*

Plant Molecular Biology, 66(6), p.609 - 617, 2008/04

 Times Cited Count:135 Percentile:95.28(Biochemistry & Molecular Biology)

Journal Articles

Application of real time PCR for the quantitative detection of radiation-induced genomic DNA strand breaks

Yamauchi, Emiko*; Watanabe, Ritsuko; Oikawa, Miyoko*; Fujimoto, Hirofumi*; Yamada, Akinori*; Saito, Kimiaki; Murakami, Masahiro*; Hashido, Kazuo*; Tsuchida, Kozo*; Takada, Naoko*; et al.

Journal of Insect Biotechnology and Sericology, 77(1), p.17 - 24, 2008/02

The frequency of single strand breaks (SSBs) occurring on both strands of the pBR322 plasmid DNA region flanked by a pair of primers used for polymerase chain reaction (PCR) amplifications was determined after irradiation with $$^{137}$$Cs $$gamma$$-rays. We refined that real time PCR is suitable for the detection and quantitative analysis of SSBs caused by $$gamma$$-ray irradiation. The utility of this approach was also supported by the comparison of the practical experimental data with the Monte Carlo simulation. The potential application of this PCR method for the detection of genomic DNA damage was also confirmed.

Journal Articles

Mutational reconstructed ferric chelate reductase confers enhanced tolerance in rice to iron deficiency in calcareous soil

Ishimaru, Yasuhiro*; Kim, S.*; Tsukamoto, Takashi*; Oki, Hiroyuki*; Kobayashi, Takanori*; Watanabe, Satoshi; Matsuhashi, Shimpei; Takahashi, Michiko*; Nakanishi, Hiromi*; Mori, Satoshi*; et al.

Proceedings of the National Academy of Sciences of the United States of America, 104(18), p.7373 - 7378, 2007/05

 Times Cited Count:127 Percentile:93.41(Multidisciplinary Sciences)

Journal Articles

$$^{52}$$Fe translocation from the roots to the ear of rice using a Positron Emitting Tracer Imaging System (PETIS)

Tsukamoto, Takashi*; Nakanishi, Hiromi*; Watanabe, Satoshi; Matsuhashi, Shimpei; Nishizawa, Naoko*; Mori, Satoshi*

JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 124, 2007/02

no abstracts in English

Journal Articles

$$^{52}$$Mn translocation in barley monitored using a positron-emitting tracer imaging system

Tsukamoto, Takashi*; Nakanishi, Hiromi*; Kiyomiya, Shoichiro*; Watanabe, Satoshi; Matsuhashi, Shimpei; Nishizawa, Naoko*; Mori, Satoshi*

Soil Science and Plant Nutrition, 52(6), p.717 - 725, 2006/12

 Times Cited Count:34 Percentile:62.52(Plant Sciences)

Journal Articles

Biosynthesis and secretion of mugineic acid family phytosiderophores in zinc-deficient barley

Suzuki, Motofumi*; Takahashi, Michiko*; Tsukamoto, Takashi*; Watanabe, Satoshi; Matsuhashi, Shimpei; Yazaki, Junshi*; Kishimoto, Naoki*; Kikuchi, Shoshi*; Nakanishi, Hiromi*; Mori, Satoshi*; et al.

Plant Journal, 48(1), p.85 - 97, 2006/10

 Times Cited Count:162 Percentile:95.76(Plant Sciences)

Journal Articles

Rice plants take up iron as an Fe$$^{3+}$$-phytosiderophore and as Fe$$^{2+}$$

Ishimaru, Yasuhiro*; Suzuki, Motofumi*; Tsukamoto, Takashi*; Suzuki, Kazumasa*; Nakazono, Mikio*; Kobayashi, Takanori*; Wada, Yasuaki*; Watanabe, Satoshi; Matsuhashi, Shimpei; Takahashi, Michiko*; et al.

Plant Journal, 45(3), p.335 - 346, 2006/02

 Times Cited Count:521 Percentile:99.64(Plant Sciences)

Oral presentation

Real time monitoring of transportation of the metal elements from root to shoot of rice plant using PETIS

Nakanishi, Hiromi*; Tsukamoto, Takashi*; Nishizawa, Naoko*; Mori, Satoshi*; Watanabe, Satoshi; Matsuhashi, Shimpei

no journal, , 

no abstracts in English

Oral presentation

2nd investigation and research on depth distribution in soil of radionuclides released by accident of Fukushima Dai-ichi Nuclear Power Station, TEPCO, 3; Soil characterization and sorption-desorption experiments of Cs and I

Tanaka, Shingo; Sato, Haruo; Okuma, Seichi*; Watanabe, Naoko*; Kozaki, Tamotsu*; Sato, Seichi*; Abe, Hironobu; Niizato, Tadafumi; Aoki, Kazuhiro

no journal, , 

no abstracts in English

25 (Records 1-20 displayed on this page)