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Journal Articles

Density functional theory study of solute cluster growth processes in Mg-Y-Zn LPSO alloys

Itakura, Mitsuhiro; Yamaguchi, Masatake; Egusa, Daisuke*; Abe, Eiji*

Acta Materialia, 203, p.116491_1 - 116491_9, 2021/01

 Times Cited Count:7 Percentile:87.55(Materials Science, Multidisciplinary)

Solute cluster in LPSO alloys plays a key role in their idiosyncratic plastic behavior such as kink formation and kink strengthening. Identifying the atomistic details of the cluster structure is a prerequisite for any atomistic modeling of LPSO alloys aiming for their improved strength and ductility, but there have been uncertainty about interstitial atom in the cluster. While density functional theory calculations have shown that inclusion of interstitial atom is energetically favorable, it has been unclear how the extra atom is provided, how much of the cluster have interstitial atoms, and what kind of element they are. In the present work we use density functional theory calculations to investigate the growth process of the solute cluster, specifically that of Mg-Y-Zn LPSO alloy, to determine the precise atomistic structure of solute cluster. We show that a pair of an interstitial atom and a vacancy is spontaneously created when a certain number of solute atoms are absorbed into the cluster, and all the full-grown cluster should include interstitial atom. We also show that interstitial atom is either Mg or Y atom, while Zn interstitial atom is extremely rare. These knowledge greatly simplifies atomistic modeling of solute clusters in Mg-Y-Zn alloy. Owing to the vacancies emitted from the cluster, vacancy density should be over-saturated in regions where solute clusters are growing, and the increased vacancy density accelerates cluster growth.

Journal Articles

Characterization of two types of cesium-bearing microparticles emitted from the Fukushima accident via multiple synchrotron radiation analyses

Miura, Hikaru*; Kuribara, Yuichi; Yamamoto, Masayoshi*; Sakaguchi, Aya*; Yamaguchi, Noriko*; Sekizawa, Oki*; Nitta, Kiyofumi*; Higaki, Shogo*; Tsumune, Daisuke*; Itai, Takaaki*; et al.

Scientific Reports (Internet), 10, p.11421_1 - 11421_9, 2020/07

 Times Cited Count:10 Percentile:72.45(Multidisciplinary Sciences)

Journal Articles

Hierarchically self-organized dissipative structures of filler particles in poly(styrene-$$ran$$-butadiene) rubbers

Yamaguchi, Daisuke; Yuasa, Takeshi*; Sone, Takuo*; Tominaga, Tetsuo*; Noda, Yohei*; Koizumi, Satoshi*; Hashimoto, Takeji*

Macromolecules, 50(19), p.7739 - 7759, 2017/10

 Times Cited Count:8 Percentile:37.66(Polymer Science)

We elucidated the spatial distribution of filler particles in cross-linked poly(styrene-$$ran$$-butadiene) rubbers (SBR) developed under a typical fillers/rubbers compounding process as one of dissipative structures formed under a stress field imposed on the given system. The dispersion state of the fillers in SBR was clarified on the basis of hierarchical structures consisting of five structure levels. More specifically, it has the following characteristics depending on the specific interactions: Small, compact clusters build up compact mass-fractal structures, while large, loose clusters build up open mass-fractal structures.

Journal Articles

Contrast variation by dynamic nuclear polarization and time-of-flight small-angle neutron scattering, 1; Application to industrial multi-component nanocomposites

Noda, Yohei*; Koizumi, Satoshi*; Masui, Tomomi*; Mashita, Ryo*; Kishimoto, Hiromichi*; Yamaguchi, Daisuke; Kumada, Takayuki; Takata, Shinichi; Oishi, Kazuki*; Suzuki, Junichi*

Journal of Applied Crystallography, 49(6), p.2036 - 2045, 2016/12

 Times Cited Count:14 Percentile:74.72(Chemistry, Multidisciplinary)

Journal Articles

Hierarchical structure in microbial cellulose; What happens during the drying process

Zhao, Y.; Koizumi, Satoshi; Yamaguchi, Daisuke; Kondo, Tetsuo*

European Physical Journal E, 37(12), p.129_1 - 129_12, 2014/12

 Times Cited Count:7 Percentile:34.15(Chemistry, Physical)

Journal Articles

Nanoscale structures of radiation-grafted polymer electrolyte membranes investigated via a small-angle neutron scattering technique

Sawada, Shinichi; Yamaguchi, Daisuke; Putra, A.; Koizumi, Satoshi*; Maekawa, Yasunari

Polymer Journal, 45(8), p.797 - 801, 2013/08

 Times Cited Count:9 Percentile:32.81(Polymer Science)

The nanoscale structures of graft-type polymer electrolyte membranes based on poly(ethylene-co-tetrafluoroethylene) (ETFE) films were investigated using a small-angle neutron scattering (SANS) technique. For comparison, SANS measurements were also performed on two precursor materials, the original ETFE film and polystyrene (PS)-grafted films. The SANS profiles of the grafted films showed shoulder peaks at a d-spacing of approximately 30 nm, which were attributed to the PS grafts introduced into the amorphous phases between the ETFE lamellar crystals. In the ETFE PEMs, the spacing of the polystyrene sulfonic acid (PSSA) grafts and ETFE crystals increased because the graft regions were enlarged by the volume of the attached sulfonic acid groups. Interestingly, the graft / crystal stack spacing in the PEMs did not increase from the dry- to fully-hydrated states. This finding implies restricted water absorption in the PSSA grafts between the ETFE lamellar crystals.

Journal Articles

Tolerance of anhydrobiotic eggs of the tardigrade ${it Ramazzottius varieornatus}$ to extreme environments

Horikawa, Daiki*; Yamaguchi, Ayami*; Sakashita, Tetsuya; Tanaka, Daisuke*; Hamada, Nobuyuki*; Yukuhiro, Fumiko*; Kuwahara, Hirokazu*; Kunieda, Takekazu*; Watanabe, Masahiko*; Nakahara, Yuichi*; et al.

Astrobiology, 12(4), p.283 - 289, 2012/04

 Times Cited Count:23 Percentile:70.77(Astronomy & Astrophysics)

We examined the hatchability of hydrated and anhydrobiotic eggs of the tardigrade ${it Ramazzottius varieornatus}$ to hatch after ionizing irradiation (helium ions), extremely low and high temperatures, and high vacuum. Anhydrobiotic eggs (50% lethal dose; 1690 Gy) were substantially more radioresistant than hydrated ones (50% lethal dose; 509 Gy). Anhydrobiotic eggs also have a broader temperature resistance compared with hydrated ones. Over 70% of the anhydrobiotic eggs treated at high and low temperatures, but all of the hydrated eggs failed to hatch. After exposure to high vacuum conditions, the hatchability of the anhydrobiotic eggs was comparable to that of untreated control eggs.

Journal Articles

Aspect-ratio-dependent phase transitions and concentration fluctuations in aqueous colloidal dispersions of charged platelike particles

Yamaguchi, Daisuke; Miyamoto, Nobuyoshi*; Fujita, Takako*; Nakato, Teruyuki*; Koizumi, Satoshi; Ota, Noboru*; Yagi, Naoto*; Hashimoto, Takeji

Physical Review E, 85(1), p.011403_1 - 011403_15, 2012/01

 Times Cited Count:19 Percentile:75.27(Physics, Fluids & Plasmas)

Phase transition of aqueous colloidal dispersions of charged plate-like particles of niobate nanosheets were investigated as a function of the aspect ratio ($$r_{rm asp}$$) and particle volume concentration ($$theta$$$$_{rm P}$$) by small-angle neutron scattering and small-angle X-ray scattering. The results elucidated the following three pieces of evidence: (1) the macroscopic phase separation of the dispersions into an isotropic phase and a liquid crystalline phase (LC) under the condition of (a) varying $$r_{rm asp}$$ at a constant $$theta$$$$_{rm P}$$ = 0.01, and of (b) varying $$theta$$$$_{rm P}$$ (0.01 $$leq$$ $$theta$$$$_{rm P}$$ $$leq$$ 0.025) at a constant $$r_{rm asp}$$ = 2.5$$times$$10$$^{-3}$$. (2) the $$r_{rm asp}$$-induced phase transition of the LC phase from a nematic phase to a highly periodic layered phase upon increasing r under the condition (a). (3) the LC phase having remarkable concentration fluctuations of the particles which are totally unexpected for the conventional lyotropic molecular LC but which are anticipated to be general for the plate-like colloidal particles.

Journal Articles

Azimuthal correlations of electrons from heavy-flavor decay with hadrons in $$p+p$$ and Au+Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Aramaki, Y.*; et al.

Physical Review C, 83(4), p.044912_1 - 044912_16, 2011/04

 Times Cited Count:8 Percentile:51.82(Physics, Nuclear)

Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled $$p+p$$ collisions. Here we extend these studies to two particle correlations where one particle is an electron from the decay of a heavy flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interaction between heavy quarks and the quark-gluon matter. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to $$p+p$$ collisions.

Journal Articles

Proton resonance elastic scattering in inverse kinematics on the medium heavy nucleus $$^{68}$$Zn

Imai, Nobuaki*; Hirayama, Yoshikazu*; Ishiyama, Hironobu*; Jeong, S.-C.*; Miyatake, Hiroari*; Watanabe, Yutaka*; Makii, Hiroyuki; Mitsuoka, Shinichi; Nagae, Daisuke*; Nishinaka, Ichiro; et al.

European Physical Journal A, 46(2), p.157 - 160, 2010/11

 Times Cited Count:3 Percentile:29.84(Physics, Nuclear)

Journal Articles

Correlation between the averaged internal structure and the coercive force of neodymium-iron-boron (Nd-Fe-B) sintered magnets investigated by small-angle neutron scattering

Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*

Proceedings of 21st International Workshop on Rare-Earth Permanent Magnets and their Applications (REPM 2010), p.161 - 164, 2010/08

We performed small-angle neutron scattering (SANS) measurements of Nd-Fe-B sintered magnets to get information on the averaged internal microstructure of Nd-Fe-B sintered magnets including the interfacial structure which is a key parameter to achieve a high-coercivity Dy-free Nd-Fe-B sintered magnet. SANS patterns from the Nd-Fe-B sintered magnets measured with a two-dimensional detector of a small-angle neutron scattering spectrometer SANS-J-II in the research reactor JRR-3 were sensitive to the sintering and annealing condition of the samples. These results indicate that the SANS measurement is a promising tool to investigate the correlation between the coercivity and the internal microstructure of Nd-Fe-B sintered magnets.

Journal Articles

A Combined method of small-angle neutron scattering and neutron radiography to visualize water in an operating fuel cell over a wide length scale from nano to millimeter

Iwase, Hiroki; Koizumi, Satoshi; Iikura, Hiroshi; Matsubayashi, Masahito; Yamaguchi, Daisuke; Maekawa, Yasunari; Hashimoto, Takeji

Nuclear Instruments and Methods in Physics Research A, 605(1-2), p.95 - 98, 2009/06

 Times Cited Count:31 Percentile:89.51(Instruments & Instrumentation)

We constructed an in-situ and simultaneous observation method as a result of combination between ultra-small-angle neutron scattering and neutron imaging (radiography). With this novel technique, we are able to visualize water distribution or transportation, occurring from micro to macro length scales in a polymer electrolyte fuel cell (PEFC). At a sample position of SANS-J-II at JRR-3, we installed a neutron imaging camera in order to construct an in-situ and simultaneous observation method by USANS and neutron imaging with monochromatized cold neutrons. In addition, in order to selectively observe MEA in a running PEFC by using the in-situ and simultaneous observation method, we need to replace carbon separators which cause strong small-angle scattering as a noise. To reduce this strong background, we replaced the carbon separators with the aluminium ones. As a result, the background scattering was minimized (1/10) as compared to before.

JAEA Reports

Collection of URL measurement data in 2007 at the Horonobe Underground Research Laboratory Project

Yamazaki, Masanao; Funaki, Hironori; Yamaguchi, Takehiro*; Niinuma, Hiroaki; Fujikawa, Daisuke; Sanada, Hiroyuki; Hiraga, Naoto; Tsusaka, Kimikazu

JAEA-Data/Code 2008-023, 136 Pages, 2008/11

JAEA-Data-Code-2008-023.pdf:17.08MB

This report summarizes the measurements data acquired at the Ventilation Shaft, the East Shaft and the drifts in 2007 based on the Observational Construction Program. The report summarizes for the purpose of the followings: sharing the investigation and measurements data, preventing the loss of them and acquisition the basic data for carrying out the Observational Construction Program.

Journal Articles

Imaging of translocation of $$^{62}$$Zn from the roots to the shoots in Zn/Cd hyperaccumulator ${it Thlaspi caerulescens}$ by PETIS

Sekimoto, Hitoshi*; Kawachi, Naoki; Watanabe, Satoshi; Yamaguchi, Yoshie*; Ozawa, Toyoaki*; Shima, Daisuke*; Ishikawa, Sayuki*; Fujimaki, Shu; Suzui, Nobuo; Ishii, Satomi; et al.

JAEA-Review 2008-055, JAEA Takasaki Annual Report 2007, P. 108, 2008/11

JAEA Reports

Measurement plan and observational construction program on drift excavation at the Horonobe Underground Research Laboratory Project

Yamazaki, Masanao; Yamaguchi, Takehiro; Funaki, Hironori; Fujikawa, Daisuke; Tsusaka, Kimikazu

JAEA-Research 2008-068, 45 Pages, 2008/09

JAEA-Research-2008-068.pdf:3.76MB

This report summarizes the measurement plan during construction of the underground facility based on the design in advance and the observational construction program for feedback measurements data into design and construction on subsequent steps. This report also describes about design and construction management program for contractor of underground facilities.

Journal Articles

Morphological and scattering studies of binary mixtures of block copolymers; Cosurfactant effects observed in the parameter space of temperature, blend composition, and molecular weight ratio

Fran$c{c}$ois, C.*; Yamaguchi, Daisuke; Hashimoto, Takeji

Macromolecules, 41(13), p.4828 - 4837, 2008/07

 Times Cited Count:22 Percentile:58.16(Polymer Science)

Thermoreversible order-order transitions between various morphologies occurring on binary mixtures of diblock copolymers were investigated by using small-angle X-ray scattering. The complex morphological behaviors observed here can be understood on the basis of two key features of the binary blends: the co-surfactant effect and the possibility for the chemical junctions of the shorter diblock to migrate away from the interface as segregation power decreases. As a summary of this series of studies, a three-dimensional phase diagram was constructed in the parameter space of overall volume fraction of polystyrene block in the mixture, the ratio of the degree of polymerization of long asymmetric diblock chain to that of short symmetric diblock chain and temperature. Such a phase diagram illustrates that the cosurfactant effect opens perspectives in tailoring morphologies of self-assembled, nano-structured materials.

Journal Articles

Investigation of self-assembled fractal porous-silica over a wide range of length scales using a combined small-angle scattering method

Yamaguchi, Daisuke; Mayama, Hiroyuki*; Koizumi, Satoshi; Tsujii, Kaoru*; Hashimoto, Takeji

European Physical Journal B, 63(2), p.153 - 163, 2008/05

The fractal dimensions of specific porous silica materials were investigated by a wide-q observation using ultra-small-angle neutron scattering technique. In order to control the fractal dimension of porous silica material, flaky particles made of alkylletene dimer (AKD) were employed as moulds and silica matrix was formed by sol-gel process. After the solidification of the silica matrix, the original AKD moulds were completely burnt away at high temperature (ca. 930K) and became pores having a particular fractal dimension. The fractal dimension of the pores was changeable by the compression of the AKD mould at different ratio during the sample preparation. We found that the fractal structure obtained in this study was distinctly different from those of ordinary silica aerogels.

Journal Articles

Investigation of self-assembled fractal porous-silica over a wide range of length scales using a combined small-angle scattering method

Yamaguchi, Daisuke; Mayama, Hiroyuki*; Koizumi, Satoshi; Tsujii, Kaoru*; Hashimoto, Takeji

European Physical Journal B, 63(2), p.153 - 163, 2008/05

 Times Cited Count:12 Percentile:49.68(Physics, Condensed Matter)

The unique structure of a set of self-assembled porous silica materials was characterized through a combined small-angle scattering (CSAS) method using small- and ultra-small angle neutron scattering as well as small-angle X-ray scattering. The porous silica specimens investigated were prepared by a sol-gel method under the presence of alkylketene dimer (AKD) template particles and through calcination, which leads to the development of porous silica having a mass-fractal structure over length scales from 10nm to 10$$mu$$m. Furthermore, the specimens posses a hierarchical structure, which consist of a fractal porous structure, and also contain primary silica particles less than 10 nm in size, which form a continuous silica matrix. To characterize these complex structures, observation over a broad range of length scales is indispensable. We propose a CSAS technique that serves this purpose well.

Journal Articles

Bacterium organizes hierarchical amorphous structure in microbial cellulose

Koizumi, Satoshi; Zhao, Y.; Tomita, Yoko*; Kondo, Tetsuo*; Iwase, Hiroki; Yamaguchi, Daisuke; Hashimoto, Takeji

European Physical Journal E, 26(1-2), p.137 - 142, 2008/05

 Times Cited Count:48 Percentile:84.7(Chemistry, Physical)

no abstracts in English

JAEA Reports

Effects of overpack corrosion on redox potential of bentonite pore water under geological disposal environment; Important parameter acquisition and a preliminary ${it E}$h analysis (Contract research)

Otsuka, Ichiro; Taki, Hiroshi*; Yamaguchi, Tetsuji; Iida, Yoshihisa; Yamada, Fumika; Inada, Daisuke*; Tanaka, Tadao

JAEA-Research 2008-043, 101 Pages, 2008/03

JAEA-Research-2008-043.pdf:6.24MB

The influence of carbon steel overpack corrosion on redox potential (${it E}$h) of bentonite pore water under geological disposal environment was investigated. The thermodynamics data of corrosion products, the corrosion rate of carbon steel, and the information on cathode reactions were acquired by experiments and literature survey. We conducted preliminary analysis of ${it E}$h, ascertained the validity of Phreeq C and identified important points on the analysis. Results were summarized as follows. (1) Thermodynamic data of Fe$$^{2+}$$, FeOH$$^{+}$$, Fe(OH)$$_{2}$$(aq), Fe(OH)$$_{3}$$$$^{-}$$, Fe(OH)$$_{4}$$$$^{2-}$$, Fe$$^{3+}$$, FeS$$_{2}$$(pyrite), FeCO$$_{3}$$(siderite),Fe(OH)$$_{2}$$(s), Fe$$_{3}$$O$$_{4}$$(magnetite), Fe(cr) were determined by literature survey. The solubility product of Fe$$_{2}$$CO$$_{3}$$(OH)$$_{2}$$ was determined experimentally, and thermodynamic data were estimated. (2) The corrosion rate of carbon steel was obtained as a function of pH and sulfide ion concentration. (3) After corrosion tests of carbon steel, no CH$$_{4}$$, HS$$^{-}$$ and H$$_{2}$$S, the reduction product of CO$$_{3}$$$$^{2-}$$ and SO$$_{4}$$$$^{2-}$$,were not detected in liquid and gas phases. (4) Preliminary analysis showed that the redox couple changed as HS$$^{-}$$(aq)/SO$$_{4}$$$$^{2-}$$, CH$$_{4}$$(aq)/CO$$_{3}$$$$^{2-}$$, H$$_{2}$$(aq)/H$$_{2}$$O during the evaluation period. After 1000 years, ${it E}$h attained about -500 to -600 mV (vs. NHE) or -750 mV controlled by CH$$_{4}$$(aq)/CO$$_{3}$$$$^{2-}$$,or H$$_{2}$$(aq)/H$$_{2}$$O, respectively.

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