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Your search keyword '"Sugimura, Hiroyuki"' showing total 221 results
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221 results on '"Sugimura, Hiroyuki"'

2. Interaction between substrate and probe in liquid metal Ga: Experimental and theoretical analysis

Author

Amano, Ken-ichi, Tozawa, Kentaro, Tomita, Maho, Nakano, Hiroshi, Murata, Makoto, Abe, Yousuke, Utsunomiya, Toru, Sugimura, Hiroyuki, and Ichii, Takashi

Subjects
Condensed Matter - Soft Condensed Matter, Condensed Matter - Mesoscale and Nanoscale Physics, Physics - Applied Physics, Physics - Chemical Physics
Abstract

Understanding the interaction between two bodies in a liquid metal is important for developing metals with high stiffness, strength, plasticity, and thermal stability. We conducted atomic force microscopy measurements in liquid Ga and performed a theoretical calculation in which the statistical mechanics of a simple liquid containing a quantum effect was used. The experiment and theory showed unusual behaviours in the interactions between the probe and substrate in the liquid metal. In the interactions, there were relatively numerous oscillations and large amplitudes. Furthermore, the interaction ranges were relatively long. From the theoretical calculations, we found an asymmetric property that when the probe is solvophilic and the substrate is solvophobic, the interaction tends to be repulsive; when the solvation affinities are exchanged, the interaction tends to be attractive in the close position. Our findings will be useful for understanding and controlling dispersion stabilities of nanoparticles and chemical reactions in liquid metals.

Published
2022

6. Molecular-Resolution Imaging of Ionic Liquid/Alkali Halide Interfaces with Varied Surface Charge Densities via Atomic Force Microscopy

Author

Bao, Yifan, Nishiwaki, Yuto, Kawano, Touma, Utsunomiya, Toru, Sugimura, Hiroyuki, and Ichii, Takashi

Abstract

When in contact with charged solid surfaces, ionic liquids (ILs) are known to form solvation structures consisting of alternating cation and anion layers. This phenomenon is considered to originate from the adsorption layer of counterions overcompensating the surface charge, so-called overscreening. However, the response of these layers to surfaces with near-zero or extremely high surface charge density (σ) remains inadequately understood. Here, we probe the solvation structure of ILs on alkali halide surfaces with varied surface orientations: nearly zero-charged RbI(100) and highly charged RbI(111), by employing frequency modulation atomic force microscopy with atomic resolution. Two commonly used ILs are examined in this study: 1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([C3mpyr][NTf2]) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][NTf2]). On RbI(100) surfaces with near zero σ, we observe alternating cation and anion layers, diverging from the previously proposed monolayer model for IL/alkali halide(100) interfaces. These results support the argument that overscreening occurs under low σ, even approaching zero, and reconcile conflicting experimental conclusions about low σ systems. On RbI(111) surfaces with high σ, we identify solvation structures consisting of two consecutive counterion layers. This structure aligns with the theoretically predicted crowding; a phenomenon rarely observed in commonly used ILs due to typically unreachable σ in electrochemical IL/electrode systems. Our findings indicate that alkali halide(111) surfaces are potentially valuable for exploring the crowding phenomenon in ILs, addressing the current scarcity of experimental observations.

Published
2024
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7. Association between acute myocardial infarction-to-cardiac rupture time and in-hospital mortality risk: a retrospective analysis of multicenter registry data from the Cardiovascular Research Consortium-8 Universities (CIRC-8U)

Author

Yoneyama, Kihei, Ishibashi, Yuki, Koeda, Yorihiko, Itoh, Tomonori, Morino, Yoshihiro, Shimohama, Takao, Ako, Junya, Ilari, Yuji, Yoshioka, Koichiro, Kunishima, Tomoyuki, Inami, Shu, Ishikawa, Tetsuya, Sugimura, Hiroyuki, Kozuma, Ken, Sugi, Keiki, Yoshino, Hideaki, and Akashi, Yoshihiro J.

Published
2021
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12. Successful Transvenous Implantation of a Permanent Pacemaker in a Patient with Situs Inversus with Dextrocardia Supported by Preceding Three-dimensional Computed Tomography: A Case Report

Author

Nomura, Aina, primary, Otani, Naoyuki, additional, Kokubun, Atsuhiko, additional, Mizuguchi, Satoshi, additional, Kawamoto, Shun, additional, Tomoe, Takashi, additional, Kitahara, Keijiro, additional, Sugiyama, Takushi, additional, Horie, Yasuto, additional, Sugimura, Hiroyuki, additional, and Yasu, Takanori, additional

Published
2024
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20. Examination of anticoagulant performance of airless hemodialysis circuit Arch Loop

Author

Kamiyama, Takuma, primary, Yamaguchi, Takeshi, additional, Nozawa, Yusuke, additional, Arisaka, Yasuhiro, additional, Fujiwara, Shinri, additional, Akaki, Show, additional, Oyamada, Ryo, additional, Kaneko, Yoshiro, additional, Sasaki, Yumi, additional, Aida, Takanobu, additional, Murayama, Mio, additional, Ueno, Asuka, additional, Hoshiai, Megumi, additional, Horie, Yasuto, additional, Sugimura, Hiroyuki, additional, Yasu, Takanori, additional, and Kawamoto, Shinya, additional

Published
2023
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24. Effects of pitavastatin on walking capacity and CD34+/133+ cell number in patients with peripheral artery disease

Author

Arao, Kenshiro, Yasu, Takanori, Endo, Yasuhiro, Funazaki, Toshikazu, Ota, Yoshimi, Shimada, Kazunori, Tokutake, Eiichi, Naito, Naoki, Takase, Bonpei, Wake, Minoru, Ikeda, Nahoko, Horie, Yasuto, Sugimura, Hiroyuki, Momomura, Shin-ichi, Kawakami, Masanobu, and Investigators of the Anti-Arteriosclerosis and Lipid Lowering with Pitavastatin Evaluation Study in Nippon (ALPEN)

Published
2017
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25. Surface potential and local conductivity measurements of micropatterned aromatic monolayers covalently attached to n-Si(111) via Si-C and Si-O bonds

Author

Garcia, Maria Carmela T., Utsunomiya, Toru, Ichii, Takashi, and Sugimura, Hiroyuki

Abstract

The surface potentials and local conductivity of self-assembled monolayers (SAMs) formed using aromatic molecules covalently bonded to n-type silicon (111) via Si–C and Si–O bonds were measured using Kelvin probe force microscopy (KPFM) and conductive AFM (CAFM). Surface potential measurements were done using micropatterned SAMs with hexadecyl SAM as a reference to eliminate surface potential variations due to the cantilever tips. Micropatterning was conducted via vacuum ultraviolet photolithography at λ = 172 nm. Ellipsometry, X-ray photoelectron spectroscopy, static water contact angle and atomic force microscopy tests show that the aromatic SAMs were well-organized despite the short molecular lengths of the precursors. KPFM results show that Si–C bonded SAMs have higher surface potentials compared to Si–O SAMs, which is in agreement with dipole moments estimated by Molecular Orbital Package semi-empirical computations. CAFM scans showed conductive domains for the aromatic SAM regions, and Si–O SAMs exhibited a higher current than Si–C SAMs.

Published
2022

27. Chemical Etching of Silicon Assisted by Graphene Oxide in an HF–HNO₃ Solution and Its Catalytic Mechanism

Author

Kubota, Wataru, Utsunomiya, Toru, Ichii, Takashi, and Sugimura, Hiroyuki

Subjects
Anions, Silicon, Transfer reactions, Etching, Defects
Abstract

Chemical etching of silicon assisted by various types of carbon materials is drawing much attention for the fabrication of silicon micro/nanostructures. We developed a method of chemical etching of silicon that utilizes graphene oxide (GO) sheets to promote the etching reaction in a hydrofluoric acid–nitric acid (HF–HNO₃) etchant. By using an optimized composition of the HF–HNO₃ etchant, the etching rate under the GO sheets was 100 times faster than that of our HF–H₂O₂ system used in a previous report. Kinetic analyses showed that the activation energy of the etching reaction was almost the same at both the bare silicon and GO-covered areas. We propose that adsorption sites for the reactant in the GO sheets enhance the reaction frequency, leading to a deeper etching in the GO areas than the bare areas. Furthermore, GO sheets with more defects were found to have higher catalytic activities. This suggests that defects in the GO sheets function as adsorption sites for the reactant, thereby enhancing the etching rate under the sheets.

Published
2021

39. Effect of additive metal salt on ionic liquid/Li4Ti5O12 electrode interfaces investigated by atomic force microscopy.

Author

Bao, Yifan, Kitta, Mitsunori, Ichii, Takashi, Utsunomiya, Toru, and Sugimura, Hiroyuki

Abstract

Ionic liquids (ILs) form layered solvation structures at IL/electrode interfaces relevant to many electrochemical applications. Recently, we observed a partially disturbed solvation structure at the 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI-TFSI)/spinel lithium titanate oxide (Li4Ti5O12, LTO) electrode interface containing Li-salt and considered the Li+-ion transfer occurring at the interface as one plausible reason for this partial destruction. In this study, we investigated EMI-TFSI/LTO(111) interfaces with the addition of K-salt or Mg-salt by frequency modulation atomic force microscopy utilizing a quartz tuning fork. It is assumed that no ion-transfer occurs at these two interfaces. The laterally consecutive solvation structures were observed at both interfaces, which strongly supported our hypothesis. Additionally, a kink in the solvation structure was observed at the interface containing Mg-salt. These results offer a comprehensive understanding of the perplexing IL/electrode interfaces with an addition of metal salt. [ABSTRACT FROM AUTHOR]

Published
2022
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49. Is the Prognosis Favourable in Patients without Cardiogenic Shock on Admission Following Acute Myocardial Infarction in the Left Main Trunk?

Author

Morioka, Hidemi, primary, Koeda, Yorihiko, additional, Itoh, Tomonori, additional, Morino, Yoshihiro, additional, Mizutani, Tomohiro, additional, Ako, Junya, additional, Nakano, Masataka, additional, Yoshioka, Koichiro, additional, Ikari, Yuji, additional, Inami, Shu, additional, Sakuma, Masashi, additional, Taguchi, Isao, additional, Ishikawa, Tetsuya, additional, Sugimura, Hiroyuki, additional, Sugi, Keiki, additional, Matsumoto, Kazuo, additional, Mitarai, Takanobu, additional, Kunishima, Tomoyuki, additional, Akashi, Yoshihiro J., additional, Nomura, Takahiro, additional, Kohzuma, Ken, additional, Fukushi, Kei, additional, and Yoshino, Hideaki, additional

Published
2020
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