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Journal Articles

Apparent diffusion coefficients of Cs and I in hardened cement paste using mineral admixtures

Mihara, Morihiro; Harasawa, Shuichi*; Torii, Kazuyuki*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 26(1), p.15 - 23, 2019/06

Hardened cement pastes (HCPs) of water/cement ratio (W/C) 50% and 30% using fly ash (FA), blast furnace slag (BFS) and silica fume (SF) for 28 days were prepared. Apparent diffusion coefficients (D$$_{a}$$) of Cs and I in HCPs were obtained using electron probe microanalysis. For Cs, BFS and SF contributed to a reduction of D$$_{a}$$ for W/C=50% and 30%, respectively. For I, BFS reduced D$$_{a}$$ for W/C=50%, however a significant reduction in D$$_{a}$$ for W/C=30% was not observed. Using SF enhanced sorption of Cs on HCP, and using BFS slightly improved sorption of Cs on HCP. It was also confirmed that the pore structures of HCP using SF and BFS were connected by fine pores. It was therefore considered that using SF and BFS contributes to the reduction of D$$_{a}$$ in HCP.

Journal Articles

Extraction behavior of rutherfordium as a cationic fluoride complex with a TTA chelate extractant from HF/HNO $$_{3}$$ acidic solutions

Yokoyama, Akihiko*; Kitayama, Yuta*; Fukuda, Yoshiki*; Kikunaga, Hidetoshi*; Murakami, Masashi*; Komori, Yukiko*; Yano, Shinya*; Haba, Hiromitsu*; Tsukada, Kazuaki; Toyoshima, Atsushi*

Radiochimica Acta, 107(1), p.27 - 32, 2019/01

 Times Cited Count:1 Percentile:58.8(Chemistry, Inorganic & Nuclear)

Journal Articles

Radiocesium distribution in aggregate-size fractions of cropland and forest soils affected by the Fukushima nuclear accident

Koarashi, Jun; Nishimura, Shusaku; Atarashi-Andoh, Mariko; Matsunaga, Takeshi*; Sato, Tsutomu*; Nagao, Seiya*

Chemosphere, 205, p.147 - 155, 2018/08

 Times Cited Count:9 Percentile:35.67(Environmental Sciences)

There is little understanding of how soil aggregation can affect the mobility and bioavailability of $$^{137}$$Cs in soils. To explore this, soil samples were collected at seven sites under different land-use conditions in Fukushima and were separated into four aggregate-size fractions. The fractions were then analyzed for $$^{137}$$Cs content and extractability and mineral composition. In forest soils, aggregate formation was significant, and $$^{137}$$Cs was largely associated with large-sized aggregates. In contrast, there was less aggregation in agricultural field soils, and most of $$^{137}$$Cs was in the clay- and silt-sized fractions. Across all sites, the $$^{137}$$Cs extractability was higher in the large-sized aggregate fractions than in the clay-sized fractions. The results demonstrate that large-sized aggregates are a significant reservoir of potentially mobile and bioavailable $$^{137}$$Cs in organic-rich (forest and orchard) soils.

Journal Articles

Synergistic extraction equilibrium of lanthanide(III) Ions with benzoylacetone and a neutral ligand in an ionic liquid

Hatakeyama, Mizuki*; Nishiyama, Yoshio*; Nagatani, Hirohisa*; Okamura, Hiroyuki; Imura, Hisanori*

Solvent Extraction Research and Development, Japan, 25(2), p.79 - 89, 2018/00

 Times Cited Count:4 Percentile:62.09(Chemistry, Multidisciplinary)

The synergistic extraction of trivalent lanthanide ions (Ln(III)) with benzoylacetone (Hba) and trioctyphosphine oxide (TOPO) in an ionic liquid (IL), 1-butyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide ([Bmim][Tf$$_{2}$$N]), has been investigated. The extractability of Ln(III) with Hba was significantly enhanced in the presence of TOPO. The composition and extraction constants of the extracted species for each Ln(III) were determined by 3-dimensional equilibrium analysis. It was found that all Ln(III) were extracted as cationic ternary complexes such as Ln(ba)$$_{2}$$(TOPO)$$_{2}$$$$^{+}$$ or Ln(ba)(TOPO)$$_{4}$$$$^{2+}$$ with Hba and TOPO. Furthermore, the formation constants of the cationic ternary complexes in the IL indicate that Lu(ba)(TOPO)$$_{4}$$$$^{2+}$$ is the most stable complex in the IL.

Journal Articles

Ionic liquid extraction of metal(II, III) complexes with macrocyclic and chelating ligands

Okamura, Hiroyuki

Bunseki Kagaku, 66(7), p.531 - 532, 2017/07

This paper summarizes the author's doctoral thesis on analytical chemistry. In this study, the ionic liquid (IL) extraction of various metal(II, III) complexes with macrocyclic and anionic chelating ligands has been investigated to clarify the solvent effect of ILs and to demonstrate the specificity and superiority of the IL extraction systems over conventional ones. The evaluation of the extraction equilibrium of Eu(III) with 2-thenoyltrifluoroacetone (Htta) in 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C$$_{n}$$mim][Tf$$_{2}$$N]) and time-resolved laser-induced fluorescence spectroscopy revealed the specific solute-solvent interactions between Eu(tta)$$_{3}$$ and [C$$_{n}$$mim][Tf$$_{2}$$N]. The IL synergistic extraction with Htta and ${it cis}$-dicyclohexano-18-crown-6 was developed. The extractability of lighter lanthanides(III) was remarkably enhanced by a synergistic effect of crown ethers. A macrocyclic ligand (H$$_{2}$$$$beta$$DA18C6) composed of diaza-18-crown-6 and two 4-acyl-5-pyrazolones was synthesized for the extraction of Sr(II). The extraction performance of H$$_{2}$$$$beta$$DA18C6 was significantly enhanced only in [C$$_{n}$$mim][Tf$$_{2}$$N] by the intramolecular cooperative effect.

Journal Articles

Role of Tf$$_{2}$$N$$^{-}$$ anions in the ionic liquid-water distribution of europium(III) chelates

Okamura, Hiroyuki; Aoyagi, Noboru; Shimojo, Kojiro; Naganawa, Hirochika; Imura, Hisanori*

RSC Advances (Internet), 7(13), p.7610 - 7618, 2017/01

 Times Cited Count:10 Percentile:43.57(Chemistry, Multidisciplinary)

The role of bis(trifluoromethanesulfonyl)imide (Tf$$_{2}$$N$$^{-}$$) anions in the ionic liquid-water distribution systems of the Eu(III) chelates with 2-thenoyltrifluoroacetone (Htta) was investigated by the liquid-liquid distribution and time-resolved laser-induced fluorescence spectroscopy (TRLFS). The effect of the ionic liquids on the distribution constant of Eu(tta)$$_{3}$$ was evaluated by the regular solution theory. The distribution constant of Eu(tta)$$_{3}$$ in 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C$$_{n}$$mim][Tf$$_{2}$$N]) was increased dramatically by the solvation effects of Eu(tta)$$_{3}$$ in [C$$_{n}$$mim][Tf$$_{2}$$N]. TRLFS for [Eu(tta)$$_{3}$$(H$$_{2}$$O)$$_{3}$$] synthesized revealed that the Eu(tta)$$_{3}$$ chelate was almost completely dehydrated in a series of [C$$_{n}$$mim][Tf$$_{2}$$N]. The Eu(tta)$$_{3}$$ chelate exists as di- or tri-hydrates in 1-ethyl-3-methylimidazolium perchlorate ([C$$_{2}$$mim][ClO$$_{4}$$]) containing 20 M water, whereas mono-hydrated chelate was formed in [C$$_{2}$$mim][Tf$$_{2}$$N, ClO$$_{4}$$] in the presence of 0.50 M Tf$$_{2}$$N$$^{-}$$ and 20 M water. These results show that the coordinated water molecules of [Eu(tta)$$_{3}$$(H$$_{2}$$O)$$_{3}$$] were replaced by the Tf$$_{2}$$N$$^{-}$$ anions. In fact, an anionic adduct, [Eu(tta)$$_{3}$$(Tf$$_{2}$$N)]$$^{-}$$, was observed by electrospray ionization mass spectrometry in the presence of [C$$_{4}$$mim][Tf$$_{2}$$N].

Journal Articles

Local fields at nonmagnetic impurity sites in a perovskite $${rm La_{0.7}Ca_{0.3}MnO_3}$$

Sato, Wataru*; Komatsuda, Sayaka*; Osa, Akihiko; Sato, Tetsuya; Okubo, Yoshitaka*

Hyperfine Interactions, 237(1), p.113_1 - 113_6, 2016/12

 Times Cited Count:2 Percentile:29.15

The magnetic hyperfine field and electric field gradient at the$$^{111}$$Cd($$leftarrow$$ $$^{rm 111m}$$Cd) and $$^{rm 111}$$Cd($$leftarrow$$$$^{rm 111}$$In) probe nuclei introduced in a perovskite manganese oxide $${rm La_{0.7}Ca_{0.3}MnO_{3}}$$ ($$T_C$$ $$sim$$ 250 K) were measured for the study of the local magnetism and structure by means of time-differential perturbed angular correlation spectroscopy. In the ferromagnetic phase at 77 K, a very slight supertransferred magnetic hyperfine field (SMHF) ($$<$$ 0.014 T) combined with a well-defined electric field gradient was observed at the nonmagnetic $$^{111}$$Cd nucleus on the La/Ca A site. This observation suggests that the large magnetic hyperfine field ($$B_{hf}$$ = 6.9 T) measured, in our previous work, at the $$^{140}$$Ce probe nucleus on the A site originates from the contribution of a 4$$f$$ spin oriented by the SMHF from adjacent Mn ions.

Journal Articles

Year-round variations in the fluvial transport load of particulate $$^{137}$$Cs in a forested catchment affected by the Fukushima Daiichi Nuclear Power Plant accident

Matsunaga, Takeshi; Nakanishi, Takahiro; Atarashi-Andoh, Mariko; Takeuchi, Erina; Muto, Kotomi; Tsuzuki, Katsunori; Nishimura, Shusaku; Koarashi, Jun; Otosaka, Shigeyoshi; Sato, Tsutomu*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 310(2), p.679 - 693, 2016/11


 Times Cited Count:5 Percentile:38.13(Chemistry, Analytical)

Particulate $$^{137}$$Cs in stream water was collected continuously for two years in order to assess the long-term trend of the $$^{137}$$Cs discharge from the forest environment. Sampling was conducted from December 2011 to December 2013 in a mountainous stream, which received the $$^{137}$$Cs from the Fukushima Daiichi Nuclear Power Plant accident. A seasonal increase in fluvial transport load of particulate $$^{137}$$Cs associated with suspended solids (SS) was observed in August and September when rainfall was abundant. The particulate $$^{137}$$Cs concentration decreased at a faster rate than the rate due to radioactive decay. This decrease might be resulted from redistribution of the easily eroded and polluted soil surface due to heavy rain events such as typhoons. These findings indicate that the particulate $$^{137}$$Cs load was subject to the inter-annual variations in rainfalls, and decreased gradually over a long period of time due to a decrease in $$^{137}$$Cs concentration in SS.

Journal Articles

Preparation and evaluation of an astatine-211-labeled sigma receptor ligand for $$alpha$$ radionuclide therapy

Ogawa, Kazuma*; Mizuno, Yoshiaki*; Washiyama, Koshin*; Shiba, Kazuhiro*; Takahashi, Naruto*; Kozaka, Takashi*; Watanabe, Shigeki; Shinohara, Atsushi*; Odani, Akira*

Nuclear Medicine and Biology, 42(11), p.875 - 879, 2015/11

 Times Cited Count:15 Percentile:30.88(Radiology, Nuclear Medicine & Medical Imaging)

Journal Articles

Proton order-disorder phenomena in a hydrogen-bonded rhodium-$$eta$$$$^{5}$$-semiquinone complex; A Possible dielectric response mechanism

Mitsumi, Minoru*; Ezaki, Kazunari*; Komatsu, Yuki*; Toriumi, Koshiro*; Miyato, Tatsuya*; Mizuno, Motohiro*; Azuma, Nobuaki*; Miyazaki, Yuji*; Nakano, Motohiro*; Kitagawa, Yasutaka*; et al.

Chemistry; A European Journal, 21(27), p.9682 - 9696, 2015/06

 Times Cited Count:5 Percentile:74.13(Chemistry, Multidisciplinary)

Journal Articles

Production and separation of astatine isotopes in the $$^7$$Li + $$^{nat}$$Pb reaction

Nishinaka, 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:7 Percentile:33.59(Chemistry, Analytical)

Production cross sections of astatine isotopes $$^{207-211}$$At in the 29-57 MeV $$^7$$Li induced reaction with $$^{nat}$$Pb target have been measured by $$alpha$$- and $$gamma$$-ray spectrometry. Excitation functions of production cross sections have been compared with a statistical model calculation to study the reaction mechanism of $$^7$$Li + $$^{nat}$$Pb. Considerably small experimental cross sections of $$^{210}$$At and $$^{209}$$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.

Journal Articles

A Passive collection system for whole size fractions in river suspended solids

Matsunaga, Takeshi; Nakanishi, Takahiro; Atarashi-Andoh, Mariko; Takeuchi, Erina; Tsuzuki, Katsunori; Nishimura, Shusaku; Koarashi, Jun; Otosaka, Shigeyoshi; Sato, Tsutomu*; Nagao, Seiya*

Journal of Radioanalytical and Nuclear Chemistry, 303(2), p.1291 - 1295, 2015/02

 Times Cited Count:3 Percentile:63.46(Chemistry, Analytical)

An innovative, yet simple method for the passive collection of radioactive materials in river water has been developed and validated. The method employes large filter vessels, containing multiple cartridge filters. River water is led to the system naturally using a drop of the riverbed by hose from upstream. This method makes long-term, unmanned monitoring possible. In addition to regular radioactivity analyses, this method provides an opportunity for the characterization of suspended materials based on its ample collection quantities (more than several tens of grams). This method may also be applicable to sediment-bound chemicals.

Journal Articles

Extraction of astatine isotopes for development of radiopharmaceuticals using a $$^{211}$$Rn-$$^{211}$$At generator

Maeda, Eita*; Yokoyama, Akihiko*; Taniguchi, Takumi*; Washiyama, Koshin*; Nishinaka, Ichiro

Journal of Radioanalytical and Nuclear Chemistry, 303(2), p.1465 - 1468, 2015/02

 Times Cited Count:7 Percentile:33.59(Chemistry, Analytical)

The $$^{211}$$At isotope has gathered attention as a promising $$alpha$$-emitter for radionuclide therapy. We report the dependence of the distribution ratio of astatine on the concentration of HCl, and on the polarity of the organic solvent. The results will be useful for development of the $$^{211}$$Rn-$$^{211}$$At generator.

Journal Articles

Intramolecular cooperative effect of a macrocyclic receptor bearing $$beta$$-diketone fragments on the extraction of strontium into an ionic liquid

Okamura, Hiroyuki; Naganawa, Hirochika; Imura, Hisanori*; Shimojo, Kojiro

Proceedings of 20th International Solvent Extraction Conference (ISEC 2014), p.1046 - 1051, 2014/09

Journal Articles

Highly selective synergism for the extraction of lanthanoid(III) ions with $$beta$$-diketones and trioctylphosphine oxide in an ionic liquid

Okamura, Hiroyuki; Takagi, Hitomi*; Isomura, Taku*; Morita, Kotaro*; Nagatani, Hirohisa*; Imura, Hisanori*

Analytical Sciences, 30(3), p.323 - 325, 2014/03

 Times Cited Count:22 Percentile:26.33(Chemistry, Analytical)

Journal Articles

Simultaneous saccharification and fermentation from ionic liquid-pretreated biomass using ionic liquid-tolerant yeast mutant

Ninomiya, Kazuaki*; Omote, Sayuri*; Sato, Katsuya; Narumi, Issey*; Shimizu, Nobuaki*

JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 115, 2014/03

Journal Articles

Sorption of Eu(III) on granite; EPMA, LA-ICP-MS, batch and modeling studies

Fukushi, Keisuke*; Hasegawa, Yusuke*; Maeda, Koshi*; Aoi, Yusuke*; Tamura, Akihiro*; Arai, Shoji*; Yamamoto, Yuhei*; Aosai, Daisuke*; Mizuno, Takashi

Environmental Science & Technology, 47(22), p.12811 - 12818, 2013/11

 Times Cited Count:13 Percentile:53.51(Engineering, Environmental)

Eu(III) sorption on granite was examined by the combined microscopic and macroscopic approaches. Polished thin sections of the granite were reacted with solutions containing 10 $$mu$$M of Eu(III) and analyzed using EPMA and LA-ICP-MS. The Eu enrichment up to 6 wt.% was observed on most of the biotite grains. The Eu-enriched parts commonly lose K, which is the interlayer cation of biotite, indicating that the sorption mode is cation exchange in the interlayer. Batch Eu(III) sorption experiments on granite and biotite powders were conducted. The macroscopic sorption behavior of biotite was consistent with that of granite. The obtained sorption edges can be reproduced reasonably by the modeling considering single-site cation exchange reactions. Granite is complex mineral assemblages. However, the combined microscopic and macroscopic approaches revealed that elementary reactions by single phase can be representative for the bulk sorption reaction in complex mineral assemblages.

Journal Articles

Assessment of olfactory nerve by SPECT-MRI image with nasal thallium-201 administration in patients with olfactory impairments in comparison to healthy volunteers

Shiga, Hideaki*; Taki, Junichi*; Washiyama, Koshin*; Yamamoto, Jumpei*; Kinase, Sakae; Okuda, Koichi*; Kinuya, Seigo*; Watanabe, Naoto*; Tonami, Hisao*; Koshida, Kichiro*; et al.

PLOS ONE (Internet), 8(2), p.e57671_1 - e57671_8, 2013/02

 Times Cited Count:12 Percentile:32.88(Multidisciplinary Sciences)

Journal Articles

FACS-based screening for yeast clone highly expressing cellulase

Ninomiya, Kazuaki*; Nomura, Tomoyo*; Sato, Katsuya; Narumi, Issei; Shimizu, Nobuaki*

JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 108, 2013/01

Journal Articles

Specific cooperative effect of a macrocyclic receptor for metal ion transfer into an ionic liquid

Okamura, Hiroyuki; Ikeda, Atsushi*; Saito, Takumi*; Aoyagi, Noboru; Naganawa, Hirochika; Hirayama, Naoki*; Umetani, Shigeo*; Imura, Hisanori*; Shimojo, Kojiro

Analytical Chemistry, 84(21), p.9332 - 9339, 2012/11

 Times Cited Count:22 Percentile:31.05(Chemistry, Analytical)

111 (Records 1-20 displayed on this page)