宮崎 司*; 宮田 登*; 有馬 寛*; 吉良 弘*; 大内 啓一*; 笠井 聡*; 津村 佳弘*; 青木 裕之
Langmuir, 37(32), p.9873 - 9882, 2021/08
We investigated the structure of the crystalline adsorption layer of poly(vinyl alcohol) (PVA) in hot water by neutron reflectivity in two cases: when the adsorption layer is exposed on the substrate by leaching the upper bulk layer and when it is deeply embedded between a relatively thick PVA film and substrate. In both cases, the PVA adsorption layer consists of three layers on the Si substrate. The bottom layer, consisting of amorphous chains that are strongly constrained on the substrate, is not swollen even in hot water at 90C. The middle layer, consisting of amorphous chains that are much more mobile compared with those in the bottom layer, has no freedom to assume a crystalline form. Only the molecular chains in the top layer are crystallizable in the adsorption layer, leading to a heterogeneous layered structure in the film thickness direction. This layered structure is attributed to the crystallizable chains of PVA during the formation of the adsorption layer driven by hydrogen bonding. However, the structure and dynamics in the adsorption layer may differ in both cases because the molecular chains in the vicinity of the surface seem to be affected by surface effects even in the adsorption layer.
阿久津 和宏*; 吉良 弘*; 宮田 登*; 花島 隆泰*; 宮崎 司*; 笠井 聡*; 山崎 大; 曽山 和彦; 青木 裕之
Polymers (Internet), 12(10), p.2180_1 - 2180_10, 2020/10
A large background scattering originating from the sample matrix is a major obstacle for fine-structure analysis of a nanometric layer buried in a bulk material. As polarization analysis can decrease undesired scattering in a neutron reflectivity (NR) profile, we performed NR experiments with polarization analysis on a polypropylene (PP)/perhydropolysilazane-derived SiO (PDS)/Si substrate sample, having a deep-buried layer of SiO to elucidate the fine structure of the nano-PDS layer. This method offers unique possibilities for increasing the amplitude of the Kiessig fringes in the higher scattering vector (Qz) region of the NR profiles in the sample by decreasing the undesired background scattering. Fitting and Fourier transform analysis results of the NR data indicated that the synthesized PDS layer remained between the PP plate and Si substrate with a thickness of approximately 109 ;. Furthermore, the scattering length density of the PDS layer, obtained from the background subtracted data appeared to be more accurate than that obtained from the raw data. Although the density of the PDS layer was lower than that of natural SiO, the PDS thin layer had adequate mechanical strength to maintain a uniform PDS layer in the depth-direction under the deep-buried condition.
和泉 篤士*; 首藤 靖幸*; 柴山 充弘*; 吉田 鉄生*; 宮田 登*; 宮崎 司*; 青木 裕之
Macromolecules, 53(10), p.4082 - 4089, 2020/05
The interfacial structure of a hexamethylenetetramine-cured phenolic resin on a silica surface was investigated by the complementary use of X-ray and neutron reflectivity (XRR and NR, respectively). The contrast-variation technique was applied using DO for the NR analysis in which the coherent neutron scattering length density (SLD) largely changed owing to the DO absorption of the dry phenolic resin and the hydrogen-to-deuterium exchange of phenolic hydroxyl groups. The XRR profile indicated no clear interfacial structure in terms of the mass density, whereas the NR profile indicated the presence of an interfacial nanolayer on the native silica surface according to the SLD. The thickness of the interfacial layer was 1-2 nm, which was independent of the thickness of the bulk resin layer. The formation of the interfacial layer on the silica surface could be caused by preferential adsorption of the novolac resin on the silica surface via strong hydrogen bonding between phenolic units in the novolac resin and silica surface comprising silanol and silyl ether groups resulting in interfacial cross-link inhomogeneity of the phenolic resin on the silica surface in the thickness direction. To the best of our knowledge, this is the first report of an experimental elucidation of the buried interfacial structure between the phenolic resins on the silica surface at a nanometer level.
宮崎 司*; 宮田 登*; 吉田 鉄生*; 有馬 寛*; 津村 佳弘*; 鳥飼 直也*; 青木 裕之; 山本 勝宏*; 金谷 利治*; 川口 大輔*; et al.
Langmuir, 36(13), p.3415 - 3424, 2020/04
We investigated in detail the structures in the poly(vinyl alcohol) (PVA) adsorption layers on a Si substrate, which remained on the substrate after immersing the relatively thick 30 - 50 nm films in hot water, by neutron reflectometry under humid conditions. For the PVA with a degree of saponification exceeding 98 mol %, the adsorption layer exhibits a three-layered structure in the thickness direction. The bottom layer is considered to be the so-called inner adsorption layer that is not fully swollen with water vapor. This may be because the polymer chains in the inner adsorption layer are strongly constrained onto the substrate, which inhibits water vapor penetration. The polymer chains in this layer have many contact points to the substrate via the hydrogen bonding between the hydroxyl groups in the polymer chain and the silanol groups on the surface of the Si substrate and consequently exhibit extremely slow dynamics. Therefore, it is inferred that the bottom layer is fully amorphous. Furthermore, we consider the middle layer to be somewhat amorphous because parts of the molecular chains are pinned below the interface between the middle and bottom layers. The molecular chains in the top layer become more mobile and ordered, owing to the large distance from the strongly constrained bottom layer; therefore, they exhibit a much lower degree of swelling compared to the middle amorphous layer. Meanwhile, for the PVA with a much lower degree of saponification, the adsorption layer structure consists of the two-layers. The bottom layer forms the inner adsorption layer that moderately swells with water vapor because the polymer chains have few contact points to the substrate. The molecular chains in the middle layer, therefore, are somewhat crystallizable because of this weak constraint.
宮崎 司*; 宮田 登*; 浅田 光則*; 津村 佳弘*; 鳥飼 直也*; 青木 裕之; 山本 勝宏*; 金谷 利治*; 川口 大輔*; 田中 敬二*
Langmuir, 35(34), p.11099 - 11107, 2019/08
We investigated the swelling behaviors of poly(vinyl alcohol) (PVA) films deposited on Si wafers with water vapor, which is a good solvent for PVA for elucidating structural and dynamical heterogeneities in the film thickness direction. Using deuterated water vapor, structural and dynamical differences in the thickness direction can be detected easily as different degrees of swelling in the thickness direction by neutron reflectivity. Consequently, the PVA film with a degree of saponification exceeding 98 mol % exhibits a three-layered structure in the thickness direction. It is considered that an adsorption layer consisting of molecular chains that are strongly adsorbed onto the solid substrate is formed at the interface with the substrate, which is not swollen with water vapor compared with the bulk-like layer above it. The adsorption layer is considered to exhibit significantly slower dynamics than the bulk. Furthermore, a surface layer that swells excessively compared with the underneath bulk-like layer is found. This excess swelling of the surface layer may be related to a higher mobility of the molecular chains or lower crystallinity at the surface region compared to the underneath bulk-like layer. Meanwhile, for the PVA film with a much lower degree of saponification, a thin layer with a slightly lower degree of swelling than the bulk-like layer above it can be detected at the interface between the film and substrate only under a high humidity condition. This layer is considered to be the adsorption layer composed of molecular chains loosely adsorbed onto the Si substrate.
河村 聖子; 服部 高典; Harjo, S.; 池田 一貴*; 宮田 登*; 宮崎 司*; 青木 裕之; 渡辺 真朗; 坂口 佳史*; 奥 隆之
Neutron News, 30(1), p.11 - 13, 2019/05
日本の中性子散乱施設の特徴のひとつとして、循環型冷凍機のように頻繁に使われる試料環境(SE)機器は各装置の担当者が整備していることが挙げられる。装置担当者は、ユーザー実験の際、装置自体だけでなく、これらのSE機器の運用も行う。このような運用には、SE機器を装置にあわせて最適化できユーザーの要求を直接きくことができるというメリットがある。一方で、MLFのSEチームは、より高度なSE機器を使った実験を可能にするため、共通のSE機器を整備している。本レポートでは、最近のMLFにおけるSE機器の現状が紹介される。中性子装置BL11, BL19, BL21, BL17で用いられるSE機器と、SEチームによって最近整備された機器に焦点をあてる。
塚崎 克和*; 宮崎 直幸*; 松本 淳; 長江 成典*; 米村 重信*; 田ノ上 拓自*; 岩崎 憲治*; 竹市 雅俊*
Proceedings of the National Academy of Sciences of the United States of America, 111(45), p.16011 - 16016, 2014/11
Fat and Dachsous cadherins regulate cell polarity and proliferation via their heterophilic interactions at intercellular junctions. Their ectodomains are unusually large because of the repetitive EC domains, which raises questions of how they fit in regular intercellular spaces. Cadherins typically exhibit a linear topology through the binding of Ca to the linker between the EC domains. Our electron microscopic observations of mammalian Fat4 and Dachsous1 ectodomains, however, revealed that, while their N-terminal regions exhibit a linear configuration, the C-terminal regions are kinked with multiple hairpin-like bends. Notably, certain EC-EC linkers in Fat4 and Dachsous1 lost Ca-binding amino acids. When such non-Ca-binding linkers were substituted for a normal linker in E-cadherin, the mutant E-cadherins deformed more extensively than the wild-type molecule. To simulate cadherin structures with non-Ca-binding linkers, we used the elastic network model and confirmed that bent configurations can be generated by deformation of the non-Ca-binding linkers. These findings suggest that Fat and Dachsous self-bend due to the loss of Ca-binding amino acids from specific EC-EC linkers, and therefore adapt to confined spaces.
槙原 亜紀子*; 横瀬 保*; 土屋 義久*; 宮崎 良雄*; 阿部 浩之; 新藤 浩之*; 海老原 司*; 丸 明史*; 森川 剛一*; 久保山 智司*; et al.
IEEE Transactions on Nuclear Science, 60(1), p.230 - 235, 2013/02
デジタル回路において放射線耐性を飛躍的に向上させる技術として既に確立されているRadiation Hardening By Design (RHBD)技術の一つであるSOIトランジスタペアをカレントミラー回路等のアナログ回路にも拡大可能であることを検証した。具体的にはそのアナログ回路を適用したPLL回路を実際に作製し、TIARAサイクロトロン加速器を用いてイオン照射を実施した。その結果すぐれた耐放射線性を有することを確認した。