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Journal Articles

Formation of radioactive cesium microparticles originating from the Fukushima Daiichi Nuclear Power Plant accident; Characteristics and perspectives

Onuki, Toshihiko*; Satou, Yukihiko; Utsunomiya, Satoshi*

Journal of Nuclear Science and Technology, 56(9-10), p.790 - 800, 2019/09

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

Journal Articles

Removal of soluble strontium via incorporation into biogenic carbonate minerals by halophilic bacterium Bacillus sp. strain TK2d in a highly saline solution

Horiike, Takumi*; Dotsuta, Yuma*; Nakano, Yuriko*; Ochiai, Asumi*; Utsunomiya, Satoshi*; Onuki, Toshihiko; Yamashita, Mitsuo*

Applied and Environmental Microbiology, 83(20), p.e00855-17_1 - e00855-17_11, 2017/10

 Times Cited Count:8 Percentile:42.33(Biotechnology & Applied Microbiology)

Radioactive strontium ($$^{90}$$Sr) leaked into the ocean from the Fukushima Daiichi Nuclear Power Plant after the nuclear accident. Since the removal of Sr using general adsorbents is not efficient at high salinity, this study investigated removal of soluble Sr from a saline solution by biogenic carbonate minerals. An isolate, Bacillus sp. strain TK2d, from marine sediment removed more than 99 % of Sr in a saline solution. Sr adsorbed at the cell surface and then carbonate minerals containing Sr developed outside the cells.

Journal Articles

Sorption behavior of Np(V) on microbe pure culture and consortia

Onuki, Toshihiko; Kozai, Naofumi; Sakamoto, Fuminori; Utsunomiya, Satoshi*; Kato, Kenji*

Chemistry Letters, 46(5), p.771 - 774, 2017/05

 Times Cited Count:0 Percentile:100(Chemistry, Multidisciplinary)

The sorption behavior of Np(V) by the microbe consortia and by a single pure culture of Fe reducing bacterium was studied at pH between 3 and 7 in resting cell conditions. The sorption of Np(V) by the Fe reducing bacterium obtained in the inert condition and by the consortia in aerated condition were higher than by the Fe reducing bacterium in aerobic condition at pH below 5, strongly suggesting presence of other mechanism than the adsorption on microbial cell surface, i.e. reduction to Np(IV).

Journal Articles

Radioactive Cs in the estuary sediments near Fukushima Daiichi Nuclear Power Plant

Yamasaki, Shinya*; Imoto, Jumpei*; Furuki, Genki*; Ochiai, Asumi*; Onuki, Toshihiko; Sueki, Keisuke*; Namba, Kenji*; Ewing, R. C.*; Utsunomiya, Satoshi*

Science of the Total Environment, 551-552, p.155 - 162, 2016/05

 Times Cited Count:22 Percentile:23.89(Environmental Sciences)

Cesium-137 ($$^{137}$$Cs) of estuary sediment impacted by the FDNPP was measured. Increasing radioactivity was observed from surface to bottom. 90% of the $$^{137}$$Cs was strongly bound to clay minerals in the estuary sediments. These results suggest that $$^{137}$$Cs is being transported from contaminated paddy fields to the estuary.

Journal Articles

Geochemistry for the Fukushima Dai-ichi Nuclear Power Plant accident; Production, dispersion and migration of radionuclides

Tanaka, Kazuya; Takahashi, Yoshio*; Fukushi, Keisuke*; Utsunomiya, Satoshi*

Chikyu Kagaku, 49(4), p.169 - 171, 2015/12

Many studies have been carried out since the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. This paper introduces the special issue on the FDNPP accident which includes contributions from various fields covering aerosols, soil, forest, river, ocean and application of new analytical technique to samples collected in Fukushima.

Journal Articles

Radioactive Cs in the severely contaminated soils near the Fukushima Daiichi Nuclear Power Plant

Kaneko, Makoto*; Iwata, Hajime; Shiotsu, Hiroyuki; Masaki, Shota*; Kawamoto, Yuji*; Yamasaki, Shinya*; Nakamatsu, Yuki*; Imoto, Jumpei*; Furuki, Genki*; Ochiai, Asumi*; et al.

Frontiers in Energy Research (Internet), 3, p.37_1 - 37_10, 2015/09

The mobility of the aggregates of submicron-sized sheet aluminosilicate in the surface environment is a key factor controlling the current Cs migration in Fukushima.

Journal Articles

Sorption of trivalent cerium by a mixture of microbial cells and manganese oxides; Effect of microbial cells on the oxidation of trivalent cerium

Onuki, Toshihiko; Jiang, M.*; Sakamoto, Fuminori; Kozai, Naofumi; Yamasaki, Shinya*; Yu, Q.; Tanaka, Kazuya; Utsunomiya, Satoshi*; Xia, X.*; Yange, K.*; et al.

Geochimica et Cosmochimica Acta, 163, p.1 - 13, 2015/08

 Times Cited Count:10 Percentile:51.29(Geochemistry & Geophysics)

The association of Ce(III) with the microbial cell surface and the formation of Ce phosphate nano-particles are responsible for suppressing the oxidation of Ce(III) to Ce(IV) in the mixtures.

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:7 Percentile:67.8(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

Effects of CeO$$_{2}$$ nanoparticles on microbial metabolism

Masaki, Shota*; Shiotsu, Hiroyuki; Onuki, Toshihiko; Sakamoto, Fuminori; Utsunomiya, Satoshi*

Chemical Geology, 391, p.33 - 41, 2015/01

 Times Cited Count:5 Percentile:72.27(Geochemistry & Geophysics)

Distinct organic species and intracellular proteins were expressed after exposure of yeast cells to CeNPs. Although cytotoxicity was not caused by CeNPs, the results of the peptide mass fingerprint analysis of the intracellular protein revealed that Eno2p, a glycolysis enzyme, was expressed after the exposure to CeNPs. These results suggest that nanoparticles have the potential to alter microbial metabolism, leading to changes in the compositions of the released substances in the surrounding environment.

Journal Articles

Adsorption of ytterbium onto ${it Saccharomyces cerevisiae}$ fungal cells; A pH-dependent contribution of phosphoryl functional group

Jiang, M. Y.*; Onuki, Toshihiko; Yamasaki, Shinya; Tanaka, Kazuya*; Utsunomiya, Satoshi*

Journal of Radioanalytical and Nuclear Chemistry, 295(3), p.2283 - 2287, 2013/03

 Times Cited Count:3 Percentile:68.66(Chemistry, Analytical)

The adsorption of Ytterbium on the cells of yeast ${it Saccharomyces cerevisiae}$ has been studied by batch type experiment by changing solution pH. The Yb adsorption species on the yeast cell wall of the ${it Saccharomyces cerevisiae}$ was determined by extended X-ray absorption fine structure (EXAFS) spectroscopy combined with a linear combination analysis at various pHs. The results indicated that the contribution of Yb-phosphoryl species was constant between pH 3 and 5, strongly suggesting that most of the Yb was associated with undeprotonated phosphoryl functional groups.

Journal Articles

Post-adsorption process of Yb phosphate nano-particle formation by ${it Saccharomyces cerevisiae}$

Jiang, M. Y.*; Onuki, Toshihiko; Tanaka, Kazuya*; Kozai, Naofumi; Kamiishi, Eigo; Utsunomiya, Satoshi*

Geochimica et Cosmochimica Acta, 93, p.30 - 46, 2012/09

 Times Cited Count:19 Percentile:41.21(Geochemistry & Geophysics)

We have investigated the post-adsorption process of ytterbium (Yb) phosphate nano-particle formation by ${it Saccharomyces cerevisiae}$. We have elucidated the nano particle formation by TEM and EXAFS analyses, that adsorbed Yb reacts on the cell surface with the released pohosphate from inside the cell.

Journal Articles

The "Study on nuclear data by using a high intensity pulsed neutron source for advanced nuclear system" nuclear data project and the characteristics of the neutron beam line for the capture cross section experiments at J-PARC

Kiyanagi, Yoshiaki*; Kino, Koichi*; Furusaka, Michihiro*; Hiraga, Fujio*; Kamiyama, Takashi*; Kato, Kiyoshi*; Igashira, Masayuki*; Katabuchi, Tatsuya*; Mizumoto, Motoharu*; Oshima, Masumi; et al.

Journal of the Korean Physical Society, 59(2), p.1781 - 1784, 2011/08

 Times Cited Count:12 Percentile:35.92(Physics, Multidisciplinary)

The project of the comprehensive nuclear data research for the development of the advanced reactor systems had been executed successfully by eight organizations from 2005 to 2009. In this project, we constructed the pulsed neutron beamline that was aimed to obtain neutron capture cross-sections of long-lived fission products and minor actinides accurately. The energy spectra, spatial distributions, and pulses of the beam were studied by measurements and simulation calculations, and they were found to be consistent with those of the beamline design. In this paper, we present the overview of the project and the properties of the neutron beam provided by this beam line.

Journal Articles

Biological nano-mineralization of Ce phosphate by ${it Saccharomyces cerevisiae}$

Jiang, M.; Onuki, Toshihiko; Kozai, Naofumi; Tanaka, Kazuya; Suzuki, Yoshinori*; Sakamoto, Fuminori; Kamiishi, Eigo*; Utsunomiya, Satoshi*

Chemical Geology, 277(1-2), p.61 - 69, 2010/10

 Times Cited Count:26 Percentile:35.65(Geochemistry & Geophysics)

We have investigated the mechanism underlying Ce sequestration by yeast ${it Saccharomyces cerevisiae}$ after exposure to Ce(III) solution at pH 3, 4, or 5. We found that needle-shaped Ce(III) phosphate nanocrystallites with a monazite structure formed on the yeast cells by exposure to Ce(III) for 42 h, even though the initial solutions did not contain any P species. These results suggest that the sorbed Ce on the cell surfaces reacted with P released from inside the yeast cell, resulting in the formation of Ce(III) phosphate nanocrystallites.

Journal Articles

Anoxic dissolution processes of biotite; Implications for Fe behavior during Archean weathering

Murakami, Takashi*; Ito, Junichi*; Utsunomiya, Satoshi*; Kasama, Takeshi*; Kozai, Naofumi; Onuki, Toshihiko

Earth and Planetary Science Letters, 224(1-2), p.117 - 129, 2004/07

 Times Cited Count:24 Percentile:51.85(Geochemistry & Geophysics)

no abstracts in English

Oral presentation

Biomineralization of REE phosphate nano-minerals by Saccharomyces cerevisiae

Jiang, M.; Onuki, Toshihiko; Kozai, Naofumi; Tanaka, Kazuya; Suzuki, Yoshinori; Utsunomiya, Satoshi*

no journal, , 

We investigated association of Ce with yeast S. cerevisiae at pH of 3, 4, and 5. SEM analysis showed that nano-sized Ce bearing minerals were developed on the cell surface. TEM and SAED analyses showed that the Ce- bearing mineral is monazite.

Oral presentation

Biological nano-mineralization of Yb phosphate by ${it Saccharomyces cerevisiae}$

Onuki, Toshihiko; Jiang, M.; Kamiishi, Eigo*; Utsunomiya, Satoshi*; Tanaka, Kazuya; Kozai, Naofumi; Suzuki, Yoshinori*

no journal, , 

We have investigated the association of heavy REE of Yb with yeast ${it S. cerevisiae}$ after exposure at pH of 3, 4 or 5. A variety of analytical techniques including FESEM-EDS, TEM, ICP-AES, XAFS have been employed to investigate the sequestration mechanism of Yb by yeast as a function of exposure time. Ytterbium concentrations in solutions decrease as the exposure time increases. FESEM, TEM, and XAFS analyses revealed that nano-sized blocky Yb phosphate with amorphous phase formed on the yeast cells surface after 24 h. These results suggest that the sorbed Yb on the cell surfaces reacted with P released from inside of the yeast cell, resulting in the formation of amorphous Yb phosphate.

Oral presentation

SEM observation of biogenic nano-particles

Kozai, Naofumi; Jiang, M.; Utsunomiya, Satoshi*; Kuwabata, Susumu*; Onuki, Toshihiko

no journal, , 

We have observed biogenic nano-particles developed on cell surface of microorganism coated with ionic liquid by SEM. In the sample preparation, the microbial cells were coated with hydrophilic and hydrophobic ionic liquids. The biogenic nano-particles were clearly observed by SEM, when the sample were coated with hydrophilic ionic liquid. On the contrary, the cells were collapsed during SEM observation, when the sample were coated with hydrophobic ionic liquid. These results showed that the coating with hydrophilic ionic liquid is effective for analyzing nano-particles developed on microbial cell surface by SEM.

Oral presentation

Bio-mineralization associated with change in chemical states of heavy elements

Tanaka, Kazuya; Suzuki, Yoshinori*; Jiang, M.*; Utsunomiya, Satoshi*; Onuki, Toshihiko

no journal, , 

no abstracts in English

Oral presentation

Bio-mineralization of heavy elements on microbial cell surface

Onuki, Toshihiko; Tanaka, Kazuya; Jiang, M.; Kozai, Naofumi; Sakamoto, Fuminori; Suzuki, Yoshinori*; Utsunomiya, Satoshi*

no journal, , 

The interaction of heavy elements involving actinides with microorganisms has been studied by experiments. Here, we report the nanoscale mineralization process of REE phosphate on microbial cell surfaces and sorption of REE by biogenic Mn oxide. We found that dissolved Ce was accumulated on the cell surface, and precipitated as nanoscale phosphate mineral, even though no P was added in the solution. The analyses of nanoscale phosphate mineral indicate that the sorbed Ce on the cell surfaces reacted with P released from inside the yeast cell, resulting in the formation of Ce(III) phosphate nanocrystallites of monazite. The biogenic Mn oxide (plus microbial cells) showed large a positive Ce anomaly in acid solution. With increasing pH, the positive Ce anomaly became less pronounced. Furthermore, negative Ce anomalies were observed at a pH of more than 6.5. This anomaly change was caused by organic matters released by bacteria.

Oral presentation

Chemical states abalyses of CuPd nanoparticles formed in spherical shell like structured protein

Suzuki, Yoshinori*; Tanaka, Kazuya; Kogawa, Masashi*; Kamiishi, Eigo*; Utsunomiya, Satoshi*; Onuki, Toshihiko

no journal, , 

We have formed nano-particles of CuPd in ferritin protein. The size and structure of the CuPd formed were analyzed by TEM and EXAFS. TEM-EDS analysis showed the formation of CuPd in ferritin. EXAFS analysis suggests that CuPd is alloy compounds.

40 (Records 1-20 displayed on this page)