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Journal Articles

Successive phase transitions in $$R_{3}$$Ir$$_{4}$$Sn$$_{13}$$ ($$R$$: La and Ce) investigated using neutron and X-ray diffraction

Nakazato, Seiya*; Iwasa, Kazuaki*; Hashimoto, Daisuke*; Shiozawa, Mami*; Kuwahara, Keitaro*; Nakao, Hironori*; Sagayama, Hajime*; Ishikado, Motoyuki*; Ohara, Takashi; Nakao, Akiko*; et al.

JPS Conference Proceedings (Internet), 30, p.011128_1 - 011128_6, 2020/03

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:7 Percentile:38.76(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

Design of play specific to the saddle type interface and its implementation

Yokota, Sho*; Chugo, Daisuke*; Hashimoto, Hiroshi*; Kawabata, Kuniaki

Proceedings of 25th IEEE International Symposium on Robot and Human Interactive Communication, p.910 - 911, 2016/08

The purpose of this paper is to experimentally investigate specific ranges of play (software backlash, deadzone) on the saddle type interface for the personal mobility (PM), and to implement them into the control scheme.

Journal Articles

Washout of clay-rich gouge in a pregrouted fault zone and increase of groundwater inflow during tunnel excavation in Neogene siliceous mudstone (Horonobe, Japan)

Ishii, Eiichi; Hashimoto, Yuta; Inagaki, Daisuke*

Proceedings of 10th Asian Regional Conference of International Association for Engineering Geology and the Environment (IAEG ARS 2015) (USB Flash Drive), 4 Pages, 2015/09

This manuscript describes unpredicted inflow which occurred during tunnel excavation for a permeable fault zone with clay-rich gouge although the fault zone was pregrouted. Some observational evidence indicates that the gouge was increasingly washed out into the tunnel through the rockbolts penetrating the gouge and the boundary between the shotcrete and the gouge on the excavation side wall during excavation. The resultant piping/erosion of the gouge probably accelerated groundwater flow from the outer aquifer of the pregrouted zone to the tunnel. After an excavation outcrop exposing the fault zone was temporarily shotcreted, major inflow occurred from the nucleated flow channel in the fault zone, breaking the shotcrete. When a fault zone including such clay-rich gouge is pregrouted, washout of the gouge during tunnel excavation should be fully cared because the gouge itself is not cemented by pre-grouting due to its low-porosity.

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:20 Percentile:70.08(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:17 Percentile:71.93(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

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:90.25(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.

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:59.12(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:11 Percentile:48.05(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:42 Percentile:82.79(Chemistry, Physical)

no abstracts in English

Journal Articles

New insight into hierarchical structures of carbon black dispersed in polymer matrices; A Combined small-angle scattering study

Koga, Tadanori*; Hashimoto, Takeji; Takenaka, Mikihito*; Aizawa, Kazuya; Amino, Naoya*; Nakamura, Masao*; Yamaguchi, Daisuke; Koizumi, Satoshi

Macromolecules, 41(2), p.453 - 464, 2008/01

 Times Cited Count:96 Percentile:94.57(Polymer Science)

Using a combined ultra-small-angle and small-angle scattering method of neutrons and X-rays, we investigated hierarchical structures of carbon black (CB) highly loaded in polyisoprene (PI) and poly-(styrene-random-butadiene) copolymer (SBR) under mechanical field (defined respectively as CB/PI and CB/SBR) as well as in toluene under a sonic field (defined as CB/toluene). Comparison of the scattering profiles from CB/PI and CB/SBR with CB/toluene clarified that (1) the smallest structure elements of CB in PI and SBR were composed of the several unbreakable units bounded together by polymer chains (defined as "dispersible units") and (2) sizes and shapes of the dispersible units depended on the polymer matrix. (3) Moreover, the enlarged size of the dispersible unit in PI was found to enlarge the upper cutoff length of the mass-fractal structure in PI, while the mass-fractal dimensions themselves remained unchanged between PI and SBR.

Journal Articles

Work of plant data acquisition system for "MONJU"

Hashimoto, Daisuke*; Komatsu, Keiichi*; Eguchi, Kenji*; Morizono, Koji

FAPIG, (175), p.23 - 28, 2007/07

The fast breeder reactor "MONJU" (hereafter "MONJU") is equipped with the system called "MONJU Integrated Data Acquisition System (MIDAS)" to effectively acquire, accumulate and analyze relevant real-plant process data gathered from the system start-up test. At present, "MONJU" has been suspended due to a sodium leak accident that occurred in 1995. However, the main part of remodeling construction to prevent sodium leaks was completed in May, 2007 and "MONJU" is highly expected to resume its operations, stepping into the practical testing phase. In this situation, "MIDAS" has been replaced with an upgraded version before the system start-up test was resumed. This paper describes overview of the new "MIDAS" system.

Journal Articles

Hierarchical structure of niobate nanosheets in aqueous solution

Yamaguchi, Daisuke; Miyamoto, Nobuyoshi; Koizumi, Satoshi; Nakato, Teruyuki*; Hashimoto, Takeji

Journal of Applied Crystallography, 40(s1), p.s101 - s105, 2007/04

 Times Cited Count:19 Percentile:85.33(Chemistry, Multidisciplinary)

no abstracts in English

Journal Articles

Tandem analyzer crystals system doubles counting rate for Bonse-Hart ultra-small-angle neutron-scattering spectrometer

Yamaguchi, Daisuke; Koizumi, Satoshi; Motokawa, Ryuhei; Kumada, Takayuki; Aizawa, Kazuya; Hashimoto, Takeji

Physica B; Condensed Matter, 385-386(2), p.1190 - 1193, 2006/11

 Times Cited Count:15 Percentile:58.07(Physics, Condensed Matter)

A new tandem analyzing system was introduced on Bonse-Hart ultra-small angle neutron scattering (USANS) spectrometer. In the normal setup of USANS it consumes a considerable time to take a scattering profile of whole q-range (2$$times$$10$$^{-4}$$ nm$$^{-1}$$ $$<$$ q $$<$$ 7$$times$$10$$^{-2}$$ nm$$^{-1}$$, where q denotes magnitude of scattering vector) due to the step scan system, in which the scattering waves from the sample and having different q are measured step by step. To overcome this difficulty two analyzer channel-cut silicon perfect crystals were settled in tandem and each of them diffracted the scattering wave of different q. In consequence, a simultaneous detection at two different q positions was realized and the measurement time was reduced to half.

Journal Articles

Focusing and Polarized Neutron ultra-small-angle scattering spectrometer (SANS-J-II) at research reactor JRR3, Japan

Koizumi, Satoshi; Iwase, Hiroki; Suzuki, Junichi; Oku, Takayuki; Motokawa, Ryuhei; Sasao, Hajime*; Tanaka, Hirokazu; Yamaguchi, Daisuke; Shimizu, Hirohiko; Hashimoto, Takeji

Physica B; Condensed Matter, 385-386(2), p.1000 - 1006, 2006/11

 Times Cited Count:38 Percentile:81.73(Physics, Condensed Matter)

no abstracts in English

Oral presentation

Design of bone-targeted labeled oligoaspartate with $$^{99m}$$Tc and $$^{186/188}$$Re

Kiyota, Sachiko*; Uehara, Tomoya*; Ishii, Daisuke*; Akizawa, Hiromichi*; Hashimoto, Kazuyuki; Arano, Yasushi*

no journal, , 

no abstracts in English

Oral presentation

Small angle neutron scattering observation of liquid crystalline sol of niobate nanosheets

Miyamoto, Nobuyoshi; Yamaguchi, Daisuke; Nakato, Teruyuki*; Koizumi, Satoshi; Hashimoto, Takeji

no journal, , 

The structure of liquid crystalline sols of niobate nanosheets was observed by USANS, SANS, and USAXS as the function of the average lateral size L and the volume fraction $$phi$$ of the nanosheets. The nanosheets sols were obtained by a reaction of K$$_{4}$$Nb$$_{6}$$O$$_{17}$$ crystals with propylammonium followed by washing with water. The sol was ultrasonicated for 10-180 min and diluted to yield the series of the samples with different L and $$phi$$. At q$$>$$ 0.1, the peaks due to the lamellar structure of the liquid crystal were observed in the scattering curves. The basal spacing was ca. 40 nm, independent of L, at $$phi$$ = 3.6 vol % and it decreased with decreasing $$phi$$. The scattering curves at 0.01 $$<$$ q $$<$$ 0.1 depended largely on L, or the form factor of the nanosheets. At q $$<$$ 0.01 nm$$^{-1}$$, the power law of q$$^{-2.5}$$ was observed independent of L, indicating the presence of the liquid crystalline domains with mass fractal structure.

Oral presentation

Observation and analysis of the niobate nanosheet solution

Yamaguchi, Daisuke; Miyamoto, Nobuyoshi; Koizumi, Satoshi; Nakato, Teruyuki*; Hashimoto, Takeji

no journal, , 

The exfoliated K$$_{4}$$Nb$$_{6}$$O$$_{17}$$ nanosheets in the aqueous solutions were observed by (ultra-) small-angle neutron and X-ray scattering (SANS, USANS and USAXS). A comprehensive measurement revealed the assembled structure of nanosheets in wide range of q, from 3$$times$$10$$^{-4}$$ nm$$^{-1}$$ to 1 nm$$^{-1}$$, where q is the magnitude of scattering vector. The details of liquid crystalline structure formed by [Nb$$_{6}$$O$$_{17}$$]$$^{4-}$$ nanosheets, which was reflected on the scattering at higher q region ($$>$$3$$times$$10$$^{-2}$$ (nm$$^{-1}$$)), largely depend on the nanosheet lateral dimension or its volume fraction. On the other hand, at lower q region ($$<$$1$$times$$10$$^{-2}$$ (nm$$^{-1}$$)), the scattering profile shows a power law scattering of which index is -2.5 regardless of the nanosheet lateral dimension or its volume fraction, suggesting that at large scale nanosheets take similar mass fractal distribution.

Oral presentation

Structure analysis of liquid crystalline nanosheet of niobate, 1

Yamaguchi, Daisuke; Miyamoto, Nobuyoshi; Koizumi, Satoshi; Nakato, Teruyuki*; Hashimoto, Takeji

no journal, , 

no abstracts in English

54 (Records 1-20 displayed on this page)