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Bunkyō-ku, Japan

Ehara Y.,Tokyo Institute of Technology | Yasui S.,Tokyo Institute of Technology | Ishii K.,Asylum Technology Co | Funakubo H.,Tokyo Institute of Technology
Japanese Journal of Applied Physics

{100}-oriented epitaxial Pb(Zr 0:65Ti 0:35)O 3 films with various film thicknesses from 0.1 to 3 m were grown on (100)cSrRuO 3 == (100)SrTiO 3 and (100)cSrRuO 3 == (100)LaNiO 3 == (001)CaF 2 substrates. The out-of-plane/in-plane lattice parameter ratio of the films on the CaF2 substrates was larger than that on the SrTiO 3 substrates up to 1.1 m film thickness, while (90- α) (α was defined as the internal tilt angle) was almost 0. Results of analysis of Raman spectra and piezoresponse images suggest that the 1.1-m-thick film grown on the (100)cSrRuO 3 == (100)LaNiO 3 == (001)CaF 2 substrate had tetragonal symmetry with a polar-axis orientation. Moreover, the saturation polarization values of the films measured from P-E hysteresis loops correspond to the two Ps values estimated from the thermodynamic theory, assuming the change in the polar direction due to the symmetry change to tetragonal, and from the crystal distortion in tetragonal symmetry. This can be explained by the large compressive stress from the CaF2 substrate having a large thermal expansion coefficient. © 2012 The Japan Society of Applied Physics. Source

Oikawa T.,Tokyo Institute of Technology | Yasui S.,Tokyo Institute of Technology | Watanabe T.,Canon Inc. | Ishii K.,Asylum Technology Co | And 6 more authors.
Japanese Journal of Applied Physics

Films of a high-pressure perovskite phase, Bi(Mg1/2Ti 1/2)O3, were prepared on (111)c-oriented SuRuO 3-coated (111)Pt/TiO2/SiO2/(100)Si substrates. The perovskite Bi(Mg1/2Ti1/2)O3films had a (111) one-axis orientation, because their constituent grains were epitaxially grown on (111)c -oriented perovskite SrRuO3ones. The remanent polarization and piezoelectric constant measured at an applied electric field of 600 kV/cm were about 30°C/cm2 and 40 pm/V, respectively. A remarkable phase transition was not observed from room temperature to 350°C in a (111) one-axis-oriented Bi(Mg1/2Ti 1/2)O3film, suggesting that the Curie temperature of this film is above 350°C. © 2013 The Japan Society of Applied Physics. Source

Higashi T.,Toyo University | Nakajima Y.,Toyo University | Kojima M.,Toyo University | Ishii K.,Asylum Technology Co | And 3 more authors.
Chemical Physics Letters

We investigated the effects of amino acid poly-l-tyrosine (PLT) molecule decoration on the surface properties and electron transport of single-walled carbon nanotubes (SWCNTs) compared to the effects of deoxyribonucleic acid (DNA) molecule decoration. Both types of molecules had a similar effect on CNT surfaces; both were applied to tubes as charges, and increased their zeta potential. From the FET characteristics, we found that PLT molecule and DNA molecule decoration have quite different effects on the conduction mechanism of CNTs, which indicates that they are induced by different binding mechanisms. © 2010 Elsevier B.V. All rights reserved. Source

Yoshimoto K.,University of Tsukuba | Yoshimoto K.,The Interdisciplinary Center | Nishio M.,University of Tsukuba | Sugasawa H.,Asylum Technology Co | And 3 more authors.
Journal of the American Chemical Society

To examine the adsorption behavior of antibody fragments (Fab-) directly immobilized on a gold surface through S-Au linkage, analyses by surface plasmon resonance (SPR), fluorometry, and atomic force microscopy (AFM) with an excellent blocking technique by the consecutive treatments of longer-poly(ethylene glycol) (PEG) (MW = 5k) and shorter-PEG (MW = 2k), abbreviated as mixed-PEG layer formation, were performed. The results of the SPR analysis suggest that the adsorption-induced inactivation of the antigen-binding activity of Fab- took place gradually on the gold surface, where the activity disappeared almost completely at 60 min after Fab- immobilization. In contrast, in the case of Fab- coimmobilized by the mixed-PEG layer, 70% of the initial antigen-binding activity of the Fab- was retained even 60 min after the construction of the hybrid surface. Using fluorescein-labeled Fab- (FL-Fab-), fluorescence measurement of the constructed surface was carried out. The fluorescence of the FL-Fab- without any blocking agent on the gold surface was gradually quenched and finally decreased to 40% of the initial intensity 60 min after Fab- immobilization. The decrease in the fluorescence intensity is considered to be caused by the change in the distance between the fluorophores labeled on the Fab- and the gold surface, due to the energy transfer from the fluorophores to the gold surface. In contrast, 75% of the initial intensity was observed on the Fab-/mixed-PEG coimmobilized surface. The results obtained from the SPR and fluorometric analyses correlated well with each other; thus, the surface-induced inactivation of the antigen-binding functionality was presumably due to the conformational and/or orientation change of Fab- on the gold surface. AFM studies provided direct information on the time-dependent decrease in the height of the immobilized Fab- on the gold surface. In contrast, the coimmobilization of densely packed mixed-PEG tethered chains around the Fab- on the gold surface suppressed the decrease in the height of Fab-, presumably indicating that the conformational and/or orientation change of Fab- was suppressed by the coimmobilized mixed-PEG layer. The new findings obtained in this study are expected to be useful for the improvement of the antibody fragment method and, thus, for the construction of high-performance immuno-surfaces. © 2010 American Chemical Society. Source

Yamada T.,Nagoya University | Yamada T.,Japan Science and Technology Agency | Shibata T.,Nagoya University | Ishii K.,Asylum Technology Co | And 4 more authors.
Japanese Journal of Applied Physics

Ferroelectric and piezoelectric Bi4Ti3O12 was epitaxially grown on TiO2(101) with a(b)-axis orientation by pulsed laser deposition (PLD). Owing to the strong growth anisotropy indigenous to bismuth-layered perovskites including Bi4Ti3O 12, it grew rapidly along the a- and b-axes and slowly along the c-axis. Therefore, at low deposition temperatures below 700 °C, Bi 4Ti3O12 nuclei did not merge with each other along the c-axis during the growth, which resulted in the formation of the nanowall-like structure. It was found that the width of nanowalls decreased with decreasing deposition temperature, which implies that the surface diffusivity of PLD species plays a role in changing the width of nanowalls. It was also found that the interval of nanowalls can be effectively controlled by adjusting the oxygen pressure during the deposition. © 2013 The Japan Society of Applied Physics. Source

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