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Mao, W.; Gao, S.*; Gong, W.; Bai, Y.*; Harjo, S.; Park, M.-H.*; Shibata, Akinobu*; Tsuji, Nobuhiro*
Acta Materialia, 256, p.119139_1 - 119139_16, 2023/09
Times Cited Count：5 Percentile：90.35(Materials Science, Multidisciplinary)Transformation-induced plasticity (TRIP)-assisted steels exhibit an excellent combination of strength and ductility due to enhanced strain hardening rate associated with deformation-induced martensitic transformation (DIMT). Quantitative evaluation on the role of DIMT in strain hardening behavior of TRIP-assisted steels and alloys can provide guidance for designing advanced materials with strength and ductility synergy, which is, however, difficult since the phase composition keeps changing and both stress and plastic strain are dynamically partitioned among constituent phases during deformation. In the present study, tensile deformation with 
neutron diffraction measurement was performed on an Fe-24Ni-0.3C (wt.%) TRIP-assisted austenitic steel. The analysis method based on stress partitioning and phase fractions measured by neutron diffraction was proposed, by which the tensile flow stress and the strain hardening rate of the specimen were resolved into factors associated with each phase, i.e., the austenite matrix, deformation-induced martensite, and the transformation rate of DIMT after differentiation, and then the role of each factor in the global strain hardening behavior was discussed. In addition, the plastic strain partitioning between austenite and martensite was indirectly estimated using the dislocation density measured by diffraction profile analysis, which constructed the full picture of stress and strain partitioning between austenite and martensite in the material. The results suggested that both the transformation rate and the phase stress borne by the deformation-induced martensite played important roles in the global tensile properties of the material. The proposed decomposition analysis method could be widely applied to investigating mechanical behavior of multi-phase alloys exhibiting the TRIP phenomenon.
Chong, Y.*; Gholizadeh, R.*; Tsuru, Tomohito; Zhang, R.*; Inoue, Koji*; Gao, W.*; Godfrey, A.*; Mitsuhara, Masatoshi*; Morris, J. W. Jr.*; Minor, A. M.*; et al.
Nature Communications (Internet), 14, p.404_1 - 404_11, 2023/02
Times Cited Count：6 Percentile：93.59(Multidisciplinary Sciences)Interstitial oxygen embrittles titanium, particularly at cryogenic temperatures, which necessitates a stringent control of oxygen content in fabricating titanium and its alloys. Here, we propose a structural strategy, via grain refinement, to alleviate this problem. Compared to a coarse-grained counterpart that is extremely brittle at 77K, the uniform elongation of an ultrafine-grained (UFG) microstructure (grain size 
2.0 
m) in Ti-0.3wt.%O was successfully increased by an order of magnitude, maintaining an ultrahigh yield strength inherent to the UFG microstructure. This unique strength-ductility synergy in UFG Ti-0.3wt.%O was achieved via the combined effects of diluted grain boundary segregation of oxygen that helps to improve the grain boundary cohesive energy and enhanced 
dislocation activities that contribute to the excellent strain hardening ability. The present strategy could not only boost the potential applications of high strength Ti-O alloys at low temperatures, but could also be applied to other alloy systems, where interstitial solution hardening results into an undesirable loss of ductility.
neutron diffraction and electron microscopy studyZheng, R.*; Gong, W.; Du, J.-P.*; Gao, S.*; Liu, M.*; Li, G.*; Kawasaki, Takuro; Harjo, S.; Ma, C.*; Ogata, Shigenobu*; et al.
Acta Materialia, 238, p.118243_1 - 118243_15, 2022/10
Times Cited Count：17 Percentile：93.62(Materials Science, Multidisciplinary)Liu, B.*; Feng, R.*; Busch, M.*; Wang, S.*; Wu, H.*; Liu, P.*; Gu, J.*; Bahadoran, A.*; Matsumura, Daiju; Tsuji, Takuya; et al.
ACS Nano, 16(9), p.14121 - 14133, 2022/09
Times Cited Count：49 Percentile：98.33(Chemistry, Multidisciplinary)Liu, M.*; Gong, W.; Zheng, R.*; Li, J.*; Zhang, Z.*; Gao, S.*; Ma, C.*; Tsuji, Nobuhiro*
Acta Materialia, 226, p.117629_1 - 117629_13, 2022/03
Times Cited Count：45 Percentile：99.49(Materials Science, Multidisciplinary)Mao, W.; Gao, S.*; Bai, Y.*; Park, M.-H.*; Shibata, Akinobu*; Tsuji, Nobuhiro*
Journal of Materials Research and Technology, 17, p.2690 - 2700, 2022/03
Times Cited Count：9 Percentile：83.6(Materials Science, Multidisciplinary)Metastable austenitic steels having ultrafine grained (UFG) microstructures can be fabricated by conventional cold rolling and annealing processes by utilizing the deformation-induced martensitic transformation during cold rolling and its reverse transformation to austenite upon annealing. However, such processes are not applicable when the austenite has high mechanical stability against deformation-induced martensitic transformation, since there is no sufficient amount of martensite formed during cold rolling. In the present study, a two-step cold rolling and annealing process was applied to an Fe-24Ni-0.3C metastable austenitic steel having high mechanical stability. Prior to the cold rolling, a repetitive subzero treatment and reverse annealing treatment were applied. Such a treatment dramatically decreased the mechanical stability of the austenite and greatly accelerated the formation of deformation-induced martensite during the following cold rolling processes. As a result, the grain refinement was significantly promoted, and a fully recrystallized specimen with a mean austenite grain size of 0.5 mm was successfully fabricated, which exhibited both high strength and high ductility.
Cs concentrations in east Japanese riversTsuji, Hideki*; Ishii, Yumiko*; Shin, M.*; Taniguchi, Keisuke*; Arai, Hirotsugu*; Kurihara, Momo*; Yasutaka, Tetsuo*; Kuramoto, Takayuki*; Nakanishi, Takahiro; Lee, S*; et al.
Science of the Total Environment, 697, p.134093_1 - 134093_11, 2019/12
Times Cited Count：17 Percentile：59.38(Environmental Sciences)To investigate the main factors that control the dissolved radiocesium concentration in river water in the area affected by the Fukushima Daiichi Nuclear Power Plant accident, the correlations between the dissolved Cs concentrations at 66 sites normalized to the average Cs inventories for the watersheds with the land use, soil components, topography, and water quality factors were assessed. We found that the topographic wetness index is significantly and positively correlated with the normalized dissolved Cs concentration. Similar positive correlations have been found for European rivers because wetland areas with boggy organic soils that weakly retain Cs are mainly found on plains. However, for small Japanese river watersheds, the building area ratio in the watershed strongly affected the dissolved Cs concentration.
Kurihara, Momo*; Yasutaka, Tetsuo*; Aono, Tatsuo*; Ashikawa, Nobuo*; Ebina, Hiroyuki*; Iijima, Takeshi*; Ishimaru, Kei*; Kanai, Ramon*; Karube, Jinichi*; Konnai, Yae*; et al.
Journal of Radioanalytical and Nuclear Chemistry, 322(2), p.477 - 485, 2019/11
Times Cited Count：2 Percentile：21.58(Chemistry, Analytical)We assessed the repeatability and reproducibility of methods for determining low dissolved radiocesium concentrations in freshwater in Fukushima. Twenty-one laboratories pre-concentrated three of 10 L samples by five different pre-concentration methods (prussian-blue-impregnated filter cartridges, coprecipitation with ammonium phosphomolybdate, evaporation, solid-phase extraction disks, and ion-exchange resin columns), and activity of radiocesium was measured. The z-scores for all of the Cs results were within 
2, indicating that the methods were accurate. The relative standard deviations (RSDs) indicating the variability in the results from different laboratories were larger than the RSDs indicating the variability in the results from each separate laboratory.
neutron diffraction study on the deformation of a TRIP-assisted multi-phase steel composed of ferrite, austenite and martensiteLavakumar, A.*; Park, M. H.*; Gao, S.*; Shibata, Akinobu*; Okitsu, Yoshitaka*; Gong, W.; Harjo, S.; Tsuji, Nobuhiro*
IOP Conference Series; Materials Science and Engineering, 580, p.012036_1 - 012036_6, 2019/09
Times Cited Count：3 Percentile：83.68(Engineering, Mechanical)Oe, Kazuhiro*; Attallah, M. F.*; Asai, Masato; Goto, Naoya*; Gupta, N. S.*; Haba, Hiromitsu*; Huang, M.*; Kanaya, Jumpei*; Kaneya, Yusuke*; Kasamatsu, Yoshitaka*; et al.
Journal of Radioanalytical and Nuclear Chemistry, 303(2), p.1317 - 1320, 2015/02
Times Cited Count：10 Percentile：64.63(Chemistry, Analytical)A new technique for continuous dissolution of nuclear reaction products transported by a gas-jet system was developed for superheavy element (SHE) chemistry. In this technique, a hydrophobic membrane is utilized to separate an aqueous phase from the gas phase. With this technique, the dissolution efficiencies of short-lived radionuclides of 
Mo and 
W were measured. Yields of more than 80% were observed for short-lived radionuclides at aqueous-phase flow rates of 0.1-0.4 mL/s. The gas flow-rate had no influence on the dissolution efficiency within the studied flow range of 1.0-2.0 L/min. These results show that this technique is applicable for on-line chemical studies of SHEs in the liquid phase.
Tachi, Yukio; Yotsuji, Kenji; Suyama, Tadahiro; Ochs, M.*
Journal of Nuclear Science and Technology, 51(10), p.1191 - 1204, 2014/10
Times Cited Count：21 Percentile：84.18(Nuclear Science & Technology)The integrated sorption and diffusion (ISD) model for compacted bentonites was developed based on the consistent combination of (1) the porewater chemistry model, (2) the thermodynamic sorption model (TSM), and (3) the diffusion model based on the electrical double layer (EDL) theory. This ISD model was successfully tested for various actinides with a complex chemistry (Np(V), Am(III), U(VI) under conditions where carbonate complexes are formed), by using published diffusion and sorption data (
, 
, 
) as a function of partial montmorillonite density. Quantitative agreements were observed as same as monovalent cations (Cs
, Na), anions (Cl
, I, TcO
) previously reported. The ISD model could be therefore seen to be able to predict sorption and diffusion behavior of various complex radionuclides in compacted bentonites.
/Md
reduction potential studied with flow electrolytic chromatographyToyoshima, Atsushi; Li, Z.*; Asai, Masato; Sato, Nozomi; Sato, Tetsuya; Kikuchi, Takahiro; Kaneya, Yusuke; Kitatsuji, Yoshihiro; Tsukada, Kazuaki; Nagame, Yuichiro; et al.
Inorganic Chemistry, 52(21), p.12311 - 12313, 2013/11
Times Cited Count：5 Percentile：23.58(Chemistry, Inorganic & Nuclear)The reduction behavior of mendelevium (Md) was studied using a flow electrolytic chromatography apparatus. By applying appropriate potentials on the chromatography column, the more stable Md is reduced to Md. The reduction potential of the Md + e 
Md couple was determined to be -0.160.05 V vs. a normal hydrogen electrode.
Nakatsuji, Satoru*; Kuga, Kentaro*; Kimura, Kenta*; Satake, Ryuta*; Katayama, Naoyuki*; Nishibori, Eiji*; Sawa, Hiroshi*; Ishii, Rieko*; Hagiwara, Masayuki*; Bridges, F.*; et al.
Science, 336(6081), p.559 - 563, 2012/05
Times Cited Count：114 Percentile：95.24(Multidisciplinary Sciences)Frustrated magnetic materials can remain disordered to the lowest temperatures. Such is the case for Ba
CuSb
O
, which is magnetically anisotropic at the atomic scale but curiously isotropic on mesoscopic length and time scales. We find that the frustration on the triangular lattice is imprinted in a nanostructured honeycomb lattice of Cu ions that resists a coherent static Jahn-Teller distortion. The resulting two-dimensional random-bond spin-1/2 system on the honeycomb lattice has a broad spectrum of spin-dimer like excitations and low-energy spin degrees of freedom that retain.
Tachi, Yukio; Nakazawa, Toshiyuki*; Ochs, M.*; Yotsuji, Kenji; Suyama, Tadahiro; Seida, Yoshimi; Yamada, Norikazu*; Yui, Mikazu
Radiochimica Acta, 98(9-11), p.711 - 718, 2010/11
Times Cited Count：25 Percentile：84.21(Chemistry, Inorganic & Nuclear)Diffusion and sorption of radionuclides in compacted bentonite are the key processes in the safe geological disposal. The effects of carbonate and salinity on Np(V) diffusion and sorption in compacted montmorillonite were investigated by experimental and modeling approaches. Effective diffusion coefficients () and distribution coefficients () of Np in montmorillonite compacted to dry density of 800 kg/m
were measured under four conditions with different salinities (0.05/0.5 M NaCl) and carbonate concentrations (0/0.01 M NaHCO
). The for carbonate-free conditions decreased as salinity increased, and those for carbonate conditions showed the opposite dependency. The decreased by one order of magnitude under high carbonate condition. Diffusion and sorption behaviors were interpreted by coupling the thermodynamic aqueous speciation, the thermodynamic sorption model based on ion exchange and surface complexation, and the diffusion model based on electrical double layer theory in narrow pores. The mechanistic model could be useful in predicting the sorption and diffusion behavior of complex species in compacted systems.
Tachi, Yukio; Yotsuji, Kenji; Suyama, Tadahiro; Ochs, M.*; Yui, Mikazu
JAEA-Research 2009-069, 83 Pages, 2010/03
JAEA-Research-2009-069.pdf:14.56MB
This report presents the prototype model/database for integrated sorption and diffusion (ISD2009) in bentonite systems as basis for performance assessment (PA) of geological disposal. The sorption model is based on a relatively simple 1-site surface complexation/diffuse layer model in combination with 1-site ion exchange model. The model parameters for surface chemistry/sorption are evaluated based on existing datasets for Na-montmorillonite, which covers key geochemical conditions, in consistent way. The diffusion model based on homogeneous pore structure and electrical double layer theory was developed and coupled with batch-based sorption model, then was validated by using data in compacted montmorillonite. The sorption and diffusion models were also tested by applying data in bentonite systems. The model and related parameters developed for key radionuclides such as Cs, Np(V), Ni, Am, etc. are integrated to ISD2009 database, which could be useful in future PA exercise.
Onuki, Toshihiko; Aoyagi, Hisao*; Kitatsuji, Yoshihiro; Samadfam, M.; Kimura, Yasuhiko; Purvis, O. W.*
Journal of Environmental Radioactivity, 77(3), p.339 - 353, 2004/08
Times Cited Count：16 Percentile：34.04(Environmental Sciences)no abstracts in English
Ando, Toshinari*; Isono, Takaaki; Kato, Takashi; Koizumi, Norikiyo; Okuno, Kiyoshi; Matsui, Kunihiro; Martovetsky, N.*; Nunoya, Yoshihiko; Ricci, M.*; Takahashi, Yoshikazu; et al.
IEEE Transactions on Applied Superconductivity, 12(1), p.496 - 499, 2002/03
Times Cited Count：5 Percentile：35.09(Engineering, Electrical & Electronic)no abstracts in English
across the interface between aqueous and nitrobenzene solutions in the presence of Octyl(phenyl)-N,N-diisobutylcarbamoyl-methyl-phosphine oxide (CMPO)Ying, M.*; Kitatsuji, Yoshihiro; Kimura, Takaumi; Yoshida, Zenko
Journal of Nuclear and Radiochemical Sciences, 2(1-2), p.11 - 15, 2001/12
no abstracts in English
Kato, Takashi; Tsuji, Hiroshi; Ando, Toshinari; Takahashi, Yoshikazu; Nakajima, Hideo; Sugimoto, Makoto; Isono, Takaaki; Koizumi, Norikiyo; Kawano, Katsumi; Oshikiri, Masayuki*; et al.
Fusion Engineering and Design, 56-57, p.59 - 70, 2001/10
Times Cited Count：17 Percentile：74.85(Nuclear Science & Technology)no abstracts in English
Al conductor with stainless steel conduitKoizumi, Norikiyo; Takahashi, Yoshikazu; Nakajima, Hideo; Tsuchiya, Yoshinori; Matsui, Kunihiro; Nunoya, Yoshihiko; Ando, Toshinari; Hiyama, Tadao; Kato, Takashi; Isono, Takaaki; et al.
Teion Kogaku, 36(8), p.478 - 485, 2001/08
no abstracts in English
