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坂口 佳史*; 高田 慎一; 川北 至信; 藤村 由希; 近藤 啓悦
Journal of Physics; Condensed Matter, 35(41), p.415403_1 - 415403_11, 2023/10
被引用回数：0 パーセンタイル：0(Physics, Condensed Matter)It is well-known that eutectic gold-silicon (Au-Si) alloys exhibit anomalous melting point depression, which is more than 1000 
C from the melting point of elemental Si (1414 C). The melting point depression in eutectic alloys is generally explained in terms of a decrease of the free energy by mixing. However, it is difficult to understand the anomalous melting point depression only from the stability of the homogeneous mixing. Some researchers suggest that there are concentration fluctuations in the liquids, where the atoms are inhomogeneously mixed. In this paper, we measure the small-angle neutron scattering (SANS) of Au
Si
(eutectic composition) and Au
Si
(off-eutectic composition) at temperatures from room temperature to 900 C in both solid and liquid states to observe such concentration fluctuations directly.
大平 征史*; 片島 拓弥*; 内藤 瑞*; 青木 大輔*; 吉川 祐介*; 岩瀬 裕希*; 高田 慎一; 宮田 完二郎*; Chung, U.-I.*; 酒井 崇匡*; et al.
Advanced Materials, 34(13), p.2108818_1 - 2108818_9, 2022/01
被引用回数：13 パーセンタイル：89.15(Chemistry, Multidisciplinary)DNA duplexes are ideal crosslinkers for building such gels because of their excellent sequence addressability and flexible tunability in bond energy. However, the mechanical responses of most DNA gels are complicated and unpredictable. The melting curve analysis of the DNA gels reveals the good correspondence between the thermodynamic potentials of the DNA crosslinkers and the presimulated values by DNA calculators. Stress-relaxation tests and dissociation kinetics measurements show that the macroscopic relaxation time of the DNA gels is approximately equal to the lifetime of the DNA crosslinkers over 4 orders of magnitude from 0.1-2000 s. Furthermore, a series of durability tests find the DNA gels are hysteresis-less and self-healable after the applications of repeated temperature and mechanical stimuli.
長尾 道弘*; Kelley, E. G.*; Faraone, A.*; 齋藤 真器名*; 依田 芳卓*; 黒葛 真行*; 高田 慎一; 瀬戸 誠*; Butler, P. D.*
Physical Review Letters, 127(7), p.078102_1 - 078102_7, 2021/08
被引用回数：21 パーセンタイル：87.71(Physics, Multidisciplinary)Membrane viscosity is a fundamental property that controls molecular transport and structural rearrangements in lipid membranes. Given its importance in many cell processes, various experimental and computational methods have been developed to measure the membrane viscosity, yet the estimated values depend highly on the method and vary by orders of magnitude. Here we investigate the molecular origins of membrane viscosity by measuring the nanoscale dynamics of the lipid acyl tails using X-ray and neutron spectroscopy techniques. The results show that the membrane viscosity can be estimated from the structural relaxation times of the lipid tails.
原田 雅史*; 高田 慎一; 岩瀬 裕希*; 梶谷 修司*; 門浦 弘明*; 金谷 利治*
ACS Omega (Internet), 6(23), p.15257 - 15263, 2021/06
被引用回数：19 パーセンタイル：77.12(Chemistry, Multidisciplinary)The ionomers distributed on carbon particles in the catalyst layer of polymer electrolyte fuel cells (PEFCs) govern electrical power via proton transport and oxygen permeation to active platinum. Thus, ionomer distribution is a key, to PEFC performance. This distribution is characterized by ionomer adsorption and deposition onto carbon during the catalyst-ink coating process; however, the adsorbed and deposited ionomers cannot easily be distinguished in the catalyst layer. Therefore, we identified these two types of ionomers based on the positional correlation between the ionomer and carbon Particles. From fitting with a model for a fractal aggregate of polydisperse core-shell spheres we determined the adsorbed-ionomer thickness on the carbon particle to be 51 angstrom land the deposited-ionomer amount for the total ionomer to be 50%. Our technique for ionomer differentiation can be used to optimally design PEFC catalyst layers.
Kumar, S.*; Saha, D.*; 高田 慎一; Aswal, V. K.*; 瀬戸 秀紀
Applied Physics Letters, 118(15), p.153701_1 - 153701_7, 2021/04
被引用回数：6 パーセンタイル：50.26(Physics, Applied)We report the pathways to suppress or enhance the protein adsorption on nanoparticles and thereby control the stability of the nanoparticle-protein complexes with the help of selective additives. This has been achieved by tuning the electrostatic interaction between the nanoparticles and proteins, in the presence of surfactant and multivalent counterions. The preferential binding of the proteins with the surfactant and multivalent ions induced charge reversibility of nanoparticles can lead to adsorption of an otherwise non-adsorbing protein and vice versa. The findings are demonstrated for anionic silica nanoparticles and two globular proteins [lysozyme (cationic) and bovine serum albumin (BSA) (anionic)] as model systems, in the presence of two ionic surfactants [anionic sodium dodecyl sulfate (SDS) and cationic dodecyltrimethylammonium bromide (DTAB)], and ZrCl
as multivalent salt.
Pallbo, J.*; 今井 正幸*; Gentile, L.*; 高田 慎一; Olsson, U.*; Sparr, E.*
Frontiers in Physiology (Internet), 11, p.592117_1 - 592117_13, 2020/12
被引用回数：6 パーセンタイル：39.96(Physiology)In this paper we investigate interactions between an aggregating peptide and phospholipid membranes, focusing on the nanometer-scale structures of the aggregates formed, as well as on the effect on the aggregation process. As a model system, we use the small amyloid-forming peptide named NACore, which is a fragment of the central region of the protein alpha-synuclein that is associated with Parkinson's disease. We find that phospholipid vesicles readily associate with the amyloid fibril network in the form of highly distorted and trapped vesicles that also may wet the surface of the fibrils.
Singh, H.*; Ray, D.*; Kumar, S.*; 高田 慎一; Aswal, V. K.*; 瀬戸 秀紀
Physical Review E, 102(6), p.062601_1 - 062601_11, 2020/12
被引用回数：10 パーセンタイル：73.47(Physics, Fluids & Plasmas)The interaction of nanoparticles with surfactants is extensively used in a wide range of applications from enhancing colloidal stability to phase separation processes as well as in the synthesis of noble functional materials. The interaction is highly specific depending on the charged nature of the surfactant. In the case of nonionic surfactants, the micelles adsorb on the surface of nanoparticles. The adsorption of nonionic surfactant C12E10 as a function of surfactant concentration for two different sizes of anionic silica nanoparticles (16 and 27 nm) has been examined using dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The study on different-sized nanoparticles shows that the lower curvature enhances the packing fraction whereas the loss of surface-to-volume ratio suppresses the fraction of adsorbed micelles with the increase in the nanoparticle size.
野田 昂志*; 土肥 侑也*; 太田 豊*; 高田 慎一; 高野 敦志*; 松下 裕秀*
Journal of Polymer Science, 58(15), p.2098 - 2107, 2020/08
被引用回数：8 パーセンタイル：36.57(Polymer Science)A four-branched cage-shaped poly(ethylene oxide) (4C-PEO) was prepared by a coupling reaction at very dilute condition between two kinds of end-functional four-armed star-shaped PEOs having amino and 
-hydroxysuccinimide groups on their four ends, followed by purification using 
-cyclodextrin (-CD). The raw coupling reaction product shows multiple peaks including various high molecular weight multimeric products in size-exclusion chromatography measurements, while the product after -CD purification shows a single peak eluted slightly earlier than the precursor star PEOs. These results suggest that the targeted 4C-PEO polymer was successfully isolated through the -CD purification. Small-angle neutron scattering (SANS) measurements of the final product in dilute solution were conducted, and its chain conformation was evaluated from the scattering profile in comparison with linear and star polymers.
Gupit, C. I.*; Li, X.*; Maekawa, Ryosuke*; Hasegawa, Naoki*; 岩瀬 裕希*; 高田 慎一; 柴山 充弘*
Macromolecules, 53(4), p.1464 - 1473, 2020/02
被引用回数：15 パーセンタイル：62.25(Polymer Science)The present work involved a systematic analysis of both the structural and rheological properties of Nafion dispersions carefully prepared using a standard procedure, ranging from dilute (0.1 wt %) to highly concentrated (30 wt %) conditions. Small-angle X-ray scattering confirmed the cylindrical structure of Nafion in dispersion and the unique interactions of Nafion particles acting as polyelectrolytes. Three different scaling relationships involving the zero-shear viscosities of the Nafion dispersions were determined for specific concentration regimes. However, at the upper concentration limit of approximately 30 wt %, the viscosity greatly deviated from these scaling relationships and significant shear thinning was observed. Simultaneous analyses using rheology and small-angle neutron scattering determined fully isotropic spatial correlations on a length scale of less than 60 nm, even when high shear was applied.
-lactoglobulin吉田 亨次*; 禪院 知寛*; Fujiyoshi, Ayako*; 真田 雄介*; 山口 敏男*; Murata, Kunihiko*; 高田 慎一; 廣井 孝介; 竹清 貴浩*; 吉村 幸浩*
Journal of Molecular Liquids, 293, p.111477_1 - 111477_9, 2019/11
被引用回数：8 パーセンタイル：43.54(Chemistry, Physical)Differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), small-angle neutron scattering (SANS) measurements, and scanning and transmission electron microscope (SEM and TEM) of -lactoglobulin (-LG) are performed in alkyl (methyl, ethyl, and propyl) ammonium nitrate ionic liquids (RAN-ILs)-water mixtures at 25-100C. The addition of these RANs decreased the thermal denaturation temperature of -LG, and the effect is larger with an increase of the hydrophobic part of the cation of the ILs. In ethyl ammonium nitrate (EAN) and propyl ammonium nitrate (PAN) mixtures, the fractal aggregate structure of -LG was found after the thermal denaturation occurred. These results are similar to those of alcohol-water mixtures. The nanoheterogeneous structure of the RAN-water mixture which consists of the hydrophobic and hydrophilic parts might affect the aggregation structure of -LG.
金子 文俊*; 河口 達也*; Radulescu, A.*; 岩瀬 裕希*; 森川 利明*; 高田 慎一; 西浦 正芳*; Hou, Z.*
Review of Scientific Instruments, 90(9), p.093906_1 - 093906_6, 2019/09
被引用回数：3 パーセンタイル：17.59(Instruments & Instrumentation)Small angle neutron scattering (SANS) is a versatile and convenient method to investigate the higher order structure of molecular assembly systems. However, the more complicated a system of interest, the more difficult the interpretation in the SANS profile. In order to increase the reliability of structural analysis on a complicated system, it is desirable to obtain different kinds of structural information from the same sample simultaneously. Polarized infrared spectroscopy is able to provide information about the molecular structure, concentration, and orientation of each chemical species in a system. In order to utilize these advantages of polarized infrared spectroscopy, a simultaneous measurement system was built by incorporating a Fourier transform infrared (FTIR) spectrometer into a time-of-flight small angle neutron scattering instrument covering a wide Q range.
金子 文俊*; Radulescu, A.*; 岩瀬 裕希*; 高田 慎一; 西浦 正芳*; Hou, Z.*
Macromolecular Symposia, 386(1), p.1900008_1 - 1900008_5, 2019/08
被引用回数：0 パーセンタイル：0.14(Polymer Science)Syndiotactic polystyrene (sPS) forms cocrystals with a wide range of chemical species from low-mass molecules to polymeric compounds, such as polyethylene glycols. Although the sPS lattice has been confirmed to accept linear compounds, such as n-alkanes and n-fatty acids, branched molecules have not been regarded as guests until now. To investigate whether sPS can adopt branched molecules as guests, cocrystallization using three types of monoacid triacylglycerols (TAGs) with relatively short acyl chains, tricaprin, trilaurin, and trimyristin has been attempted. Moreover, the sPS films subjected to the guest exchange procedure have been investigated via X-ray diffraction, Fourier transform infrared spectroscopy, and simultaneous small- and wide-angle neutron scattering. The results showed that sPS forms the monoclinic delta clathrate cocrystal with all the three TAGs.
岩瀬 裕希*; 河合 里紗*; 守島 健*; 高田 慎一; 吉村 倫一*; 柴山 充弘*
Journal of Colloid and Interface Science, 538, p.357 - 366, 2019/03
被引用回数：13 パーセンタイル：41.52(Chemistry, Physical)We found that the wormlike micelles were oriented in the direction of the flow due to elongation and that changes to the precursor of the wormlike micelles did not affect the shear thickening. As a precursor structural change of shear thinning, the wormlike micelles elongated while maintaining their orientation. We found that an increase in the molecular curvature of the 12-2-12 due to the introduction of a spacer-group contributed to the unusual rheological behaviors of the wormlike micelles in a solution under shear flow.
鈴木 淳市; 大沼 正人*; 松本 貴裕*
Journal of the Physical Society of Japan, Vol.70, Supplement A, p.303 - 305, 2001/05
光るシリコンとして注目されるポーラスシリコンの発光メカニズムを解明するため、中性子及びX線小角散乱実験を行った。その結果、以下のことを明らかにした。ポーラスシリコンは、約2nmのシリコン微結晶より構成される。微結晶表面には、約0.1nmの水素・重水素層がある。微結晶サイズは、ポロシティーの増大に伴い、線型的に減少する。微結晶表面終端水素の種類は、微結晶の構造に影響を及ぼさない。ポーラスシリコンの発光特性は、これらの構造特性に対応し、シリコンの量子サイズ効果と表面フォノンを考慮したエネルギーバンドモデルにより説明できる。
前田 安*; D.Rogers*; O.Song*; 鈴木 淳市; 森井 幸生; 武井 弘次*
Journal of Applied Physics, 79(3), p.1819 - 1821, 1996/02
被引用回数：1 パーセンタイル：8.28(Physics, Applied)中性子小角散乱により、Co-12at.% Cr-2at.% Ta薄膜の微細磁気構造を観察した。中性子散乱強度には、数ナノメートルの大きさに相当する磁気散乱ピークが観測された。この結果は、高密度磁気記録に適当な微細で均一なCo高濃度成分の存在を示唆する。
武井 弘次*; 鈴木 淳市; 前田 安*; 森井 幸生
IEEE Transactions on Magnetics, 30(6), p.4029 - 4031, 1994/11
被引用回数：10 パーセンタイル：66.36(Engineering, Electrical & Electronic)高密度磁気記録材料Co-22at.%Crにおいて組成分離に伴う微細磁気構造が存在することを中性子散乱により明らかにした。組成分離は150Cから400Cの作成基板温度で顕著となる。200Cの基板温度では10nm程度の最も微細な磁気ドメイン構造が観測され、より高密度な磁気記録材料としての応用の可能性を示す。
Pr sans entraineur par l'echange d'ion夏目 晴夫
日本原子力学会誌, 4(11), p.758 - 765, 1962/00
抄録なし
前川 康成
no journal, ,
Radiation-induced grafting technique was applied to the development of proton- and anion-conducting electrolyte membranes (PEM and AEM) for hydrogen- and alkaline hydrated hydrazine-fuel cells. The graft-type PEM and AEM could solve the currently most concerned problems, conductivity and mechanical properties at low and high relative humidities (RH), respectively for a PEM and alkaline durability for a AEM. The hierarchical structures of ETFE-PEM and ETFE-AEM were investigated using small angle X-ray and neutron scattering (SAXS and SANS). The grafted ETFE membranes were characterized as being composed of conducting graft domains around ETFE lamellar crystals with a period of 20-30 nm and well-connected crystallite network domains with a d-range of 200-300 nm. The well-connected ion-channels around ETFE lamellar crystals and crystallite domains should be origin of high conductivity and mechanical properties of both graft-type PEM and AEM.
岡 弘; 丹野 敬嗣; 大塚 智史; 矢野 康英; 皆藤 威二; 大沼 正人*
no journal, ,
9Cr-ODS鋼被覆管の量産プロセス(熱間等方圧プレス(HIP)、熱間押出、熱間鍛造)の各加工熱処理段階でのナノ組織変化について評価した。加工熱処理により残留相の割合は減少し、ナノ粒子の数密度は低下した。残留相の形成はナノ粒子によるピン止め効果によると考えられている。したがって、加工熱処理がナノ粒子の数密度・サイズに影響し、残留相割合を減少させたものと考えられる。
元川 竜平; 小林 徹; 遠藤 仁*; 鈴木 伸一; 矢板 毅; 塩飽 秀啓
no journal, ,
The aim of this study is to elucidate a hierarchical structure of Zr(NO
)(2TBP) in octane, formed in an organic phase of the biphasic solvent extraction system, where TBP is tri-n-butyl phosphate. The combined method of extended X-ray adsorption fine structure (EXAFS) and small-angle scattering (SAS), exhibiting a good compatibility in the viewpoint of observing length scale, were employed in this study. EXAFS and SAS are capable of covering the length scales from 0.1-1 nm and 1-100 nm, respectively, reflecting a single coordination structure of Zr(NO)(2TBP) complex and its self-assembly. Note that we need to combine the data obtained for both methods in order to proceed with our understandings of the overall hierarchical structure. In this paper, we would like to report the overall picture of the self-assembled structure into a wide length scale and introduce an original insight into the treatment of EXAFS and SAS profiles.
