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1,061 results on '"Miyakawa, T."'

4. Inhomogeneous interface dipole effect at the Schottky junctions of PdCrO2 on β-Ga2O3(2¯01) substrates.

Author

Miyakawa, T., Harada, T., Ito, S., and Tsukazaki, A.

Subjects
*SCHOTTKY effect, *TRANSMISSION electron microscopes, *SCHOTTKY barrier, *GUM arabic, *ELECTRON affinity, *PHOTOELECTRON spectroscopy
Abstract

We report the lateral and vertical electrical conduction properties of PdCrO2 thin films grown on insulating Al2O3 (001) and conducting β-Ga2O3 (2 ¯ 01) substrates. The c-axis oriented PdCrO2 films on the both substrates showed metallic temperature dependence of in-plane resistivity down to 2 K. In PdCrO2/β-Ga2O3 vertical devices, rectifying current density–voltage (J–V) characteristics revealed the formation of a Schottky barrier at the PdCrO2/β-Ga2O3 interface. The Schottky barrier height (SBH) of 1.2–1.8 eV, evaluated by J–V characteristics, is significantly larger than 0.8 eV expected from the usual Mott–Schottky relation based on the electron affinity of β-Ga2O3 (4.0 eV) and the work function of PdCrO2 (4.8 eV) determined by ultraviolet photoelectron spectroscopy. The enhanced SBH at the PdCrO2/β-Ga2O3 interface indicates the existence of interface dipoles, as in the case of PdCoO2/β-Ga2O3. Besides, we observed a large difference of the SBH between the J–V measurements (1.2–1.8 eV) and capacitance measurements (2.0–2.1 eV). While the SBH is definitely enhanced by the interface dipole effect, the level of enhancement at the PdCrO2/β-Ga2O3 interface is rather inhomogeneous, different from that at the PdCoO2/β-Ga2O3. In fact, two typical types of interfaces were found by a high-angle annular dark-field scanning transmission electron microscope, which would be the origin of the inhomogeneous SBH. Further understanding of the interface formation between delafossite oxides and β-Ga2O3 (2 ¯ 01) will improve the performance of Ga2O3 Schottky junctions as a power diode available at high temperatures. [ABSTRACT FROM AUTHOR]

Published
2020
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10. Long-distance polarizing microscope system combined with solenoid-type magnet for microscopy and simultaneous measurement of physical parameters.

Author

Kinoshita, Y., Miyakawa, T., Xu, X., and Tokunaga, M.

Subjects
*POLARIZING microscopes, *PHYSICAL measurements, *MAGNETS, *SUPERCONDUCTING magnets, *MICROSCOPY
Abstract

We have developed a long-distance polarizing microscope system combined with a solenoid-type superconducting magnet. By inserting an infinity-corrected objective lens into the magnet, direct or polarizing microscope images are observed in magnetic fields of up to 12 T at various temperatures down to 2 K. Through magneto-optical measurements in the transmission geometry, the local magnetization process of a transparent magnet is evaluated in areas of 10 × 10 µm2. This system enables simultaneous measurements of other physical properties over a wide range of temperatures and magnetic fields. The basic principle of the proposed long-distance microscopy can be applied to imaging experiments in various research fields, particularly biology and chemistry. [ABSTRACT FROM AUTHOR]

Published
2022
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34. Squamous metaplasia of Pagetʼs disease

Author

Miyakawa, T., Togawa, Y., Matushima, H., Nakamura, H., Kamada, N., Momota, Y., Tochigi, N., Nikaido, T., Shinkai, H., and Utani, A.

Published
2004

44. Molecular Dynamics Simulation of Myopathy-related Mutant FHL1 in Water and Analysis of Structure Stabilization.

Author

Takeuchi, H., Okajima, H., Itoga, H., Nobuoka, K., Yamada, H., Miyakawa, T., Morikawa, R., Hayashi, Y. K., and Takasu, M.

Subjects
MOLECULAR dynamics, ZINC-finger proteins, MUSCLE weakness, MOLECULAR models, IODINE isotopes
Abstract

Mutations in the FHL1 gene can cause X-linked hereditary myopathy, which causes one of the rarest intractable diseases. The age of the disease onset is quite variable from early infancy to adulthood, and the patients show progressive muscle weakness and atrophy. The FHL1 protein is constituted by four and a half LIM domains. Each LIM domain contains two zinc fingers, which contribute to the structural stability of the LIM domain. A change in the cysteine or histidine residues in the 2nd LIM domain (LIM2) is closely associated with the disease severity. Therefore, LIM2 is suggested to have an essential role in maintaining the structure of FHL1. In this study, molecular dynamics simulation was performed on molecular models consisting of LIM1 and LIM2 of wild and mutant FHL1. We calculated the extent of distortion of zinc finger structure and measured the distance between zinc atom and Cα atom of zinc-coordinated residues. Our analysis showed that the correlation between these two quantities is larger in the mutants associated with severe myopathy. [ABSTRACT FROM AUTHOR]

Published
2019
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46. Structure and Hydrogen Bonds of γS-crystallin and γS-G18V Studied by Molecular Dynamics Simulation.

Author

Ozawa, A., Yamada, H., Mori, S., Noguchi, Y., Miyakawa, T., Morikawa, R., and Takasu, M.

Subjects
HYDROGEN bonding, MOLECULAR dynamics, PROTEIN analysis, CRYSTAL structure, GLYCINE, TEMPERATURE effect
Abstract

The γS-crystallin protein maintains transparency and increases the reflection index of the eye lens. Here, γS-G18V, a mutant of γS-crystallin, was studied, in which the 18th residue, glycine, is replaced by valine. This mutation is associated with childhood-onset cortical cataract. Mutated γS-crystallin forms cross-links with other proteins in the eye lens and leads to aggregation at a temperature lower than that for γS-crystallin. In this study, structural analysis of γScrystallin and γS-G18V was performed by molecular dynamics simulation. It was found that cysteine residues around the area where the mutation is introduced are arranged at the solvent side with less hydrogen bonds than in the case of γS-WT. [ABSTRACT FROM AUTHOR]

Published
2017
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