Updated on 2026/06/11

Information

 

写真a

 
IWASHITA TOMOYA
 
Organization
Faculty of Science Department of Chemistry Assistant Professor
Graduate School of Sciences Department of Chemistry(Concurrent)
School of Sciences Department of Chemistry(Concurrent)
Title
Assistant Professor
Contact information
メールアドレス

Degree

  • 博士(理学) ( 2025.3 Kyushu University )

Research Interests・Research Keywords

  • Research theme: Clarifying the role of solvation in solute diffusion and the freezing process of water droplets.

    Keyword: 液体論、拡散係数、凍結、水分活性、分子動力学シミュレーション

    Research period: 2025.4 - Present

Papers

  • Decomposition of friction coefficients to analyze hydration effects on a C<sub>60</sub>(OH)<sub>n</sub> Reviewed International journal

    Iwashita, T; Uematsu, Y; Terazima, M; Akiyama, R

    JOURNAL OF CHEMICAL PHYSICS   161 ( 24 )   2024.12   ISSN:0021-9606 eISSN:1089-7690

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Journal of Chemical Physics  

    To analyze hydration effects on macromolecular diffusion, the friction coefficients of macromolecules were examined using molecular dynamics simulations with an all-atom model. In the present study, a method was introduced to decompose the molecular friction coefficient into the contributions for each site on the macromolecule. The method was applied to several fullerenols in ambient water. The friction coefficients for the hydrophilic part, such as the OH group, were larger than those for the hydrophobic part, such as the C. The hydration effect did not depend only on the kind of functional group but also on the surface roughness. This approach would be useful in explaining the experimentally observed large changes in diffusion coefficients of proteins that were accompanied by conformation changes.

    DOI: 10.1063/5.0241914

    Web of Science

    Scopus

    PubMed

  • Usefulness of higher-order system-size correction for macromolecule diffusion coefficients: A molecular dynamics study Reviewed International journal

    Iwashita, T; Nagao, M; Yoshimori, A; Terazima, M; Akiyama, R

    CHEMICAL PHYSICS LETTERS   807   2022.11   ISSN:0009-2614 eISSN:1873-4448

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Chemical Physics Letters  

    Yeh and Hummer's simplified estimation method has often been adopted to obtain diffusion coefficients for solute molecules using molecular dynamic simulation. However, the simplified formula is not necessarily valid when a small basic cell is used. Therefore, we conducted molecular dynamics simulations of aqueous protein solution to estimate the diffusion coefficient for the infinite dilution limit. We confirmed a deviation from the simplified formula in the simulation data and rationalized the discrepancy based on the unsimplified formula.

    DOI: 10.1016/j.cplett.2022.140096

    Web of Science

    Scopus

Presentations

  • MDを用いたフラレノール表面のOH基の露出による拡散係数低下の分析

    第19回分子科学討論会  2025.9 

  • 分子動力学法を用いた巨大分子の拡散係数への溶媒和効果の解析手法の開発

    第47回溶液化学シンポジウム  2025.10 

MISC

  • 分子動力学シミュレーションを用いた巨大分子の拡散係数における水和効果の評価法

    岩下 智哉 ; 植松 祐輝 ; 寺嶋正秀 ; 秋山, 良

    2026.3

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    Authorship:Lead author  

    DOI: https://doi.org/10.14943/lowtemsci.84.75

Research Projects

  • 液滴の光共振特性を活用した「光分子効果」の定量的解明

    2025.9 - 2026.9

    九州大学 理学研究院若手支援令和1号資金 

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    Grant type:Donation

  • 氷結核生成から探る、水の多形を踏まえた水分活性の分子論的解明

    Grant number:25K23596  2025.7 - 2027.3

    Grants-in-Aid for Scientific Research  Grant-in-Aid for Research Activity Start-up

    岩下 智哉

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    Grant type:Scientific research funding

    「水分活性(Aw)」は、水溶液の性質を包括的に記述できる熱力学的指標として食品・生物学などの分野で広く用いられている。しかし、Awが意味する物理化学的描像は依然として未解明である。この問題の解明は、「水のポリアモルフィズム(水の多形)」の熱力学的挙動の理解のほか、食品衛生法における食品の保存基準の科学的裏付けにも波及効果を持つ。本研究では、真空中液滴の氷結を実験的題材として、Awの物理化学的描像の解明という課題に対し、分子動力学シミュレーションも活用した、実験と理論の融合的アプローチで挑む。その中で、水のポリアモルフィズムという視点を取り入れ、Awの分子論的意味を明らかにすることを目指す。

    CiNii Research

Class subject

  • 構造・量子化学実験

    2025.4 - Present   Winter quarter

  • 基本操作法

    Second semester

Outline of Social Contribution and International Cooperation activities

  • ESSP, a research experience program for high school students. In the program, participants were assigned research topics, conducted experiments and discussions, and ultimately presented their findings at a research presentation session.

Social Activities

  • ESSP、高校生を対象とした研究体験プログラム。研究テーマを提示したうえで実験および考察を行ってもらい、最終的に研究報告会でプレゼンテーションを実施してもらった。

    Role(s):Advisor, Organizing member

    2025.8

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    Audience:High school students

    Type:Seminar, workshop