Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Tokunaga, Kohei; Takahashi, Yoshio*; Kozai, Naofumi
Journal of Nuclear and Radiochemical Sciences (Internet), 23, p.14 - 19, 2023/00
Tanaka, Nobuyuki; Sawada, Shinichi*; Yamaki, Tetsuya*; Kodaira, Takahide*; Kimura, Takehiro*; Nomura, Mikihiro*
Chemical Engineering Science, 237, p.116575_1 - 116575_11, 2021/06
Times Cited Count：1 Percentile：5.78(Engineering, Chemical)We have been developing the ion exchange membranes by a radiation grafted polymerization method to improve HI concentration performance for Electro-electrodialysis (EED) in the thermochemical water-splitting hydrogen production iodine-sulfur process. In this work, the crosslinking structures were introduced to the ion exchange membranes. The proton conductivity (
), transport number (t
), and water permeation factor (
) of these crosslinked ion exchange membranes were measured and the effect of crosslinks to these performance indexes were investigated. The introduction of crosslinks was found to improve the selectivity of H
and water transport (increase of t and decrease of ), although the somewhat decreased. The EED model that we established to discuss the permeation mechanism of EED system was used to theoretically analyze the effect of crosslink on the performance indexes. Based on this analysis of measurement results, the introduction of the crosslink was found to little affect the absorbed amount of HIx solution and H diffusion coefficient in the tested membranes, whereas it could lead to decrease I
diffusion coefficient. The results of and t could reflect these effects. In addition, we found the fact that crosslink can inhibit the swelling due to the absorption of the HIx solution. As a result, the value decreased owing to the introduction of crosslink.
Kusaka, Ryoji
Journal of Nuclear and Radiochemical Sciences (Internet), 20, p.28 - 31, 2020/06
Miyamoto, Yutaka; Yasuda, Kenichiro
Journal of Nuclear and Radiochemical Sciences (Internet), 18, p.13 - 15, 2018/07
A sequential separation technique using an anion-exchange column developed in the previous works have the potential to completely separate picograms of Am from the lanthanides using mixtures of acetic acid, hydrochloric acid, and nitric acid as the eluents, without any functional ligands or special columns. This experimental result implies that ultra-trace actinides, including Am, Pu, U, and Th in environmental samples can be sequentially separated by combination of these mixed-media eluents and an anion exchange column.
Kamiji, Yu; Onuki, Kaoru; Kubo, Shinji
Proceedings of 5th International Conference on Chemical and Biological Sciences (ICCBS 2018) (USB Flash Drive), p.51 - 54, 2018/03
As one of the evaluation of corrosion resistance of structural materials for HI decomposition environment in the iodine-sulfur (IS) thermochemical water-splitting process, we fabricated a HI decomposer which produce practical corrosion environment for the corrosion test using test specimens and examined corrosion resistance of test specimens made of Hastelloy C-276. In the corrosion test, dry HI as the feed gas were used to realize practical environment with copresence of no steam. The experiments were carried out at 500
C and atmospheric pressure for 100h in total. Corrosion rates were evaluated from the weight change of each specimen after exposure. Test specimens set in the catalyst layer suffered relatively severe corrosion (
0.75 mm/y) in comparison with those set before the catalyst layer ( 0.52 mm/y).
Shiga, Motoyuki
Reference Module in Chemistry, Molecular Sciences and Chemical Engineering (Internet), 22 Pages, 2018/00
Nuclear quantum effects are important in molecular systems containing light elements such as hydrogen. For example large zero vibration and proton tunneling in hydrogen bonded systems originate from nuclear quantum effects. We herein describe path integral molecular dynamics (PIMD) where nuclear quantum effects are taken into account based on imaginary time path integral theory. PIMD provides numerically exact solutions for quantum statistics of complex molecular systems in thermal equilibrium. Centroid and ring polymer molecular dynamics are extensions to provide approximate quantum dynamics. Combination with ab initio electronic structure calculations enables simulation of the whole entity of many-electron many-nuclei systems.
Booth, S. G.*; Uehara, Akihiro*; Chang, S.-Y.*; La Fontaine, C.*; Fujii, Toshiyuki*; Okamoto, Yoshihiro; Imai, Takahito*; Schroeder, S. L. M.*; Dryfe, R. A. W.*
Chemical Science, 8(12), p.7954 - 7962, 2017/12
Times Cited Count：33 Percentile：72.1(Chemistry, Multidisciplinary)The two-phase Brust-Schiffrin synthesis of alkane thiol protected metal nanoparticles has been shown to undergo significantly different processes dependent on the precursor species and reactant conditions. In this work X-ray absorption spectroscopy is used in conjunction with liquid/liquid electrochemistry in order to highlight the significance of B
r; to the reaction mechanism. We propose that the observed behavior of [AuBr
]; species described herein explain a deviation in reported behavior present in the current literature. The reported mechanistic understanding should enable a nanoparticle synthesis with a higher yield and reduce size polydispersity.
Kaneko, Masashi; Watanabe, Masayuki; Miyashita, Sunao*; Nakashima, Satoru*
Journal of Nuclear and Radiochemical Sciences (Internet), 17, p.9 - 15, 2017/03
Density functional calculations were applied to the complexation of Eu(III) and Am(III) ions with phosphinic acid (O-donor) and dihiophosphinic acid (S-donor) from the viewpoint of the bonding nature of valence orbitals in metal ion. Two and four conformers for S-donor and O-donor complexes, respectively were optimized. Their stabilization energies by complex formation toward [M(H
O)
]
were estimated. As the result, the energies reproduced the experimental Am(III)/Eu(III) selectivity that O-donor ligand preferably coordinates to Eu(III) ion, whereas S-donor ligand selectively coordinates to Am(III) ion. Focused on the bonding natures of d and f-orbital electrons, it was indicated that the d-orbital electrons in both Eu and Am complexes participate in the covalency as bonding-type nature and have the almost same contribution. Meanwhile, the contribution of the f-orbital electrons was different between Eu and Am complexes and indicated that in the case of S-donor complex, non-bonding type and bonding type contributions were observed for Eu and Am complexes, respectively and in the case of O-donor complex, bonding type and anti-bonding type contributions were observed for Eu and Am complexes, respectively. This result suggested that the bonding natures of d-orbital electrons contribute to the geometrical similarity of molecular structures for Eu and Am complexes and the bonding natures of f-orbital electrons contribute to the difference in the selectivity of Eu and Am ions.
Segawa, Tomoomi; Fukasawa, Tomonori*; Huang, A.-N.*; Yamada, Yoshikazu; Suzuki, Masahiro; Fukui, Kunihiro*
Chemical Engineering Science, 153, p.108 - 116, 2016/10
Times Cited Count：7 Percentile：26.31(Engineering, Chemical)The influence of the heating method and rate on the morphology of CuO powders synthesized from Cu(NO
)
3HO aqueous solutions by denitration was investigated. The median diameter of the obtained powder was found to decrease as the heating rate increased, independent of the heating method. The microwave heating method remarkably reduced the particle size and enhanced the irregularity and disorder of the shape and surface of the particles, which were found to be more widely distributed. In contrast, the microwave hybrid heating method yielded the most spherical particles with the smoothest surface. It was also found that this heating method sharpened the particle size distribution and had higher energy efficiency than the MW method. Numerical simulations also indicated a difference in the energy efficiency between these two methods. The simulations also revealed that the hybrid method could heat the whole reactor more uniformly with a lower microwave output.
Vela, S.*; Deumal, M.*; Shiga, Motoyuki; Novoa, J.*; Ribas-Arino, J.*
Chemical Science, 6(4), p.2371 - 2381, 2015/04
Times Cited Count：32 Percentile：68.19(Chemistry, Multidisciplinary)The magnetic properties of molecule-based magnets are commonly rationalized by considering only a single nuclear configuration of the system under study, usually X-ray crystal structure. Here, by means of a computational study in which the results obtained using such a static approach and those obtained by explicitly accounting for thermal fluctuations are compared, we uncover that the serious limitations of the static perspective when dealing with magnetic crystals whose radicals undergo wide-amplitude motions. As a proof of concept, these limitations are illustrated for magnetically bistable 1,3,5-trithia-2,4,6-triazapentalenyl (TTTA) material. The discovery that a single X-ray structure is not adequate enough to interpret the magnetic properties of TTTA is also expected to be decisive in other organic magnets with dominant exchange interactions propagating through labile 
networks.
Jinno, Satoshi; Fukuda, Yuji; Sakaki, Hironao; Yogo, Akifumi; Kanasaki, Masato; Kondo, Kiminori; Faenov, A. Y.; Skobelev, I. Yu.*; Pikuz, T.; Boldarev, A. S.*; et al.
Progress in Ultrafast Intense Laser Science XI; Springer Series in Chemical Physics, Vol.109, p.215 - 233, 2015/00
Clusters formed in supersonic gas expansion through a three-staged conical nozzle have been verified by measuring the angular distribution of the light scattered from cluster target. The size distirbutions of the clusters are calculated based on the Mie theory. The reliability of the size measurement is verified to be an experimental error of 10% using standard particles. The mean sizes of CO
clusters for the cases of CO/H and CO/He mixed-gas targets are estimated to be 0.26 
m and 0.22 m, respectively. For the CO/H, the cluster density is estimated to be 5.5 
clusters/cm
by measuring the attenuation of the laser beam intensity. Furthermore, total gas density profiles are obtained via the Abel inversion from the phase shift of the light passing through the target using an interferometer. The variation of the cluster mass fraction along the radial direction of the target is almost constant, which is consistent with a Boldarev's model.
Itakura, Ryuji; Hosaka, Koichi*; Yokoyama, Atsushi; Ikuta, Tomoya*; Kannari, Fumihiko*; Yamanouchi, Kaoru*
Progress in Ultrafast Intense Laser Science XI; Springer Series in Chemical Physics, Vol.109, p.23 - 42, 2015/00
We investigate the multichannel dissociative ionization of ethanol in intense laser fields by the photoelectron-photoion coincidence momentum imaging and identify separately the ionization and subsequent electronic excitation in ethanol. From the energy correlation between a photoelectron and a fragment ion, we reveal the amount of the internal energy gained by ethanol cations from the laser field varies depending on the respective ionization and electronic excitation pathways.
Nb and 
Ta as homologues of element 105, Db, on cation exchanger in HF/HNO solutionKasamatsu, Yoshitaka*; Toyoshima, Atsushi; Tome, Hayato*; Tsukada, Kazuaki; Asai, Masato; Haba, Hiromitsu*; Nagame, Yuichiro
Journal of Nuclear and Radiochemical Sciences (Internet), 13(1), p.9 - 12, 2013/06
Adsorption behavior of the group-5 elements, Nb and Ta, on cation-exchange resin was studied in mixed solution of HF and HNO as a model experiment of their heavier homologue, element 105 (dubnium, Db). Chemical reactions of these elements in the cation exchange rapidly reached the equilibrium. It was found that distribution coefficients of Nb and Ta decrease with increasing the fluoride ion concentration in the studied range of 10
- 10
M. Clear difference between Nb and Ta was observed in the variations of the distribution coefficients against the fluoride ion concentration. This would originate from their different chemical species of fluoride complexes. We propose the cation-exchange experiment of Db based on the present experimental results to understand its fluoride complex formation.
I and 
Cs in soil samples and a simplified calculation of cascade summing corrections for volume sourceAsai, Masato; Kaneya, Yusuke*; Sato, Tetsuya; Tsukada, Kazuaki; Oe, Kazuhiro; Sato, Nozomi; Toyoshima, Atsushi
Journal of Nuclear and Radiochemical Sciences (Internet), 12(1), p.5 - 10, 2012/06
To measure radioactivities in soil contaminated by the accident of the Fukushima Daiichi Nuclear Power Plant, efficiency calibration of Ge detectors for I, Cs, and 
Cs in volume sources was investigated. 
-ray detection efficiencies for these nuclei were determined precisely using standard soil samples containing Cs, Cs, 
Hf, and 
Zr. These standard sources were prepared by admixing radioactive solutions with soil, and point sources were made from the same solutions to determine their radioactivity concentrations. Cascade summing corrections for rays of Cs in soil samples were evaluated experimentally. To easily calculate the cascade summing corrections for volume sources, we examined a simplified method using averaged efficiencies, and evaluated its validity through a comparison of the calculated correction factors with the experimental ones.
Toyoshima, Atsushi
Journal of Nuclear and Radiochemical Sciences, 12(1), p.A1 - A6, 2012/05
Chemical studies of rutherfordium (Rf) and nobelium (No) recently carried out at JAEA are reviewed. Anion-exchange behavior of Rf in HF and HNO mixed solution was studied together with short-lived Zr and Hf isotopes using an automated chemistry apparatus. It was found that the hexafluoro complex of Rf is present in the solutions under the given conditions where the same complexes of Zr and Hf are existing. The formation constant of the Rf complex was evaluated to be at least one order of magnitude smaller than those of Zr and Hf. Oxidation experiments of No
was conducted in 0.1 M 
-hydroxyisobutyric (-HIB) acid using a newly developed electrolytic column chromatography apparatus on an atom-at-a-time scale. The result clearly demonstrated that stable No is successfully oxidized to the trivalent state, No, which is held in the -HIB solution.
Nakahara, Masaumi; Nomura, Kazunori
Chemical Engineering Science, 66(4), p.740 - 746, 2011/02
Times Cited Count：8 Percentile：26.43(Engineering, Chemical)Counter current experiments in a single cycle solvent extraction system were carried out with centrifugal contactors to study flow rate reductions in extraction solvent and stripping solution with a dissolver solution of irradiated mixed oxide fuel. Uranium and Pu leaked to the raffinate with a 15% decrease in the extraction solvent flow rate, which brought about an accumulation of U and Pu in the co-decontamination section. On the other hand, a 15% decrease in the stripping solution flow rate did not affect the stripping of U and Pu so greatly.
Usuda, Shigekazu*; Magara, Masaaki; Esaka, Fumitaka; Yasuda, Kenichiro; Kokubu, Yoko; Lee, C. G.; Miyamoto, Yutaka; Suzuki, Daisuke; Inagawa, Jun; Sakurai, Satoshi; et al.
Journal of Nuclear and Radiochemical Sciences, 11(2), p.A5 - A9, 2011/01
In the analysis of IAEA safeguards environmental samples, isotope ratios of ultra-trace amounts of uranium and plutonium in samples taken from nuclear facilities are determined to detect undeclared nuclear materials and activities. In order to keep and enhance the reliability of the measurement results, validation of analytical methods and estimation of measurement uncertainty in such ultra-trace analysis should be properly done in accordance with worldwide standards. In this paper, the current activities on achievement of QA/QC (quality assurance and quality control) and estimation of measurement uncertainty in the ultra-trace analysis at a clean chemistry laboratory (CLEAR) of JAEA are reported.
Toyoshima, Atsushi; Kasamatsu, Yoshitaka*; Tsukada, Kazuaki; Asai, Masato; Ishii, Yasuo; Tome, Hayato*; Nishinaka, Ichiro; Sato, Tetsuya; Nagame, Yuichiro; Sch
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 
Rf. It is suggested that the stability of the RfCl
2(TOPO) complex is lower than that of the corresponding species of the homologues.
Miyamoto, Yutaka; Yasuda, Kenichiro; Magara, Masaaki; Kimura, Takaumi; Usuda, Shigekazu*
Journal of Nuclear and Radiochemical Sciences, 10(2), p.7 - 12, 2009/12
With combination of a single anion-exchange column and mixed-media of CHCOOH and other acids (HCl and/or HNO), 50 ng of U, Th, Pb, and lanthanides were sequentially separated. All of the elements were recovered more than 95%, and the decontamination factor was more than 100. This separation technique reduces separation time and simplified the complicated traditional processes without any special reagents and equipments.
Nagame, Yuichiro; Haba, Hiromitsu*
Encyclopedia of Chemical Sciences, Engineering and Technology Resources (Internet), 76 Pages, 2008/00
This article gives a brief summary of the reported syntheses and nuclear properties of the transactinide elements as well as chemical investigation of those elements. Experimental techniques of single atom detection after in-flight separation with electromagnetic separators have made a breakthrough in production and identification of new transactinide nuclides. Development of automated rapid chemical separation techniques based on one atom-at-a-time scale has also considerably contributed to the progress of chemical studies of the transactinide elements. Some key experiments exploring new frontiers of the production and chemical characterization of the transactinide elements as well as the state of the art in these experimental studies are demonstrated. Prospects of extending nuclear and chemical studies of the heaviest elements in near future are shortly considered.
