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OKUZONO Tohru

    Graduate School of Pharmaceutical Sciences Department of Physical Chemistry of Colloid and Polymer　Associate Professor
Contact： okuzonophar.nagoya-cu.ac.jp
Last Updated :2025/04/25

Researcher Information

URL

J-Global ID

Research Interests

  • シミュレーション   コロイド   ソフトマター   

Research Areas

  • Natural sciences / Mathematical physics and basic theory
  • Natural sciences / Bio-, chemical, and soft-matter physics

Education

  •        -   Kyushu University  Graduate School of Sciences  Department of Physics

Association Memberships

  • American Chemical Society   日本液晶学会   高分子学会   日本物理学会   日本薬学会   

Published Papers

Books etc

  • 監修)中村, 浩; 山中, 淳平; 執筆)奥薗, 透 (Contributor第１章５ 荷電粒子によるコロイド結晶形成シミュレーション; 第２章３ 枯渇引力によるコロイド結晶形成・凝集体成長シミュレーション)シーエムシー出版 2020/05 9784781315027 v, 251p, 図版21p
  • (編集)米持, 悦生; 近藤, 伸一; 山中, 淳平; (執筆)山中, 淳平; 奥薗, 透; 豊玉, 彰子 (Contributor序章１物理量と単位 ２物理量の数学的取り扱い ３よく使う数学のまとめ; 第２章１エネルギー ２自発的な変化)廣川書店 2017/04 9784567223706 vii, 377p
  • 東京大学工学教程編纂委員会; 大岩, 顕; 奥薗, 透; 松野, 俊一; 岡, 隆史; 有田, 亮太郎 (Contributor１ ベクトル空間 ２ スカラー場、ベクトル場、テンソル場)丸善出版 2016/12 9784621301012 xi, 172p
  • Kinoshita, Shuichi (ed); Junpei Yamanaka; Tohru Okuzono; Akiko Toyotama (ContributorChapter 5 Colloidal Crystals)Elsevier 2013 9780123970145 vii, 263 p.
  • 製剤への物理化学[第2版]
    廣川書店 2012 
    共著

MISC

Research Grants & Projects

  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2021/04 -2024/03 
    Author : 山中 淳平; 奥薗 透; 豊玉 彰子
     
    サブミクロンからミクロンサイズの構造周期を持つ、ダイヤモンド型の結晶格子は、可視および赤外光を閉じ込める「完全フォトニック結晶」として働くことが知られ、実用化が待望されている。本研究では、最近開発した「2次元の負荷電コロイド結晶」を第1層とし、その上に正・負の荷電コロイド粒子を交互積層する新規手法を用い、数層以上の繰り返し単位を持つ、シート状ダイヤモンド格子を構築する。本研究では粒子間の相互作用と摩擦力を最適化することで、光学特性評価が可能な、一辺がmm以上の断面を持つ格子を作製するための方法論を確立する。 令和３年度は、粒子間静電相互作用と摩擦力の調節による２層目構造の大面積化を検討した。表面修飾が容易なシリカ粒子（市販）を一層目として用いた。また、カチオン性のシランカップリング剤を用い、正電荷を導入したシリカ粒子を２層目粒子に用いた。顕微鏡観察により１、２層目を識別するため、２層目粒子には赤色蛍光色素を導入した。各層の粒子サイズは500nmおよび1μmの２種類とした。 まず、基板の表面電荷数を最適化し、１層目粒子（負に荷電）のコロイド結晶を、mm オーダーの領域に渡って吸着させることに成功した。次に、２層目粒子の吸着位置に対する添加塩濃度依存性を検討し、２層目粒子の規則性（ボンド配向パラメーター）が完全に規則的な場合の９０％に達する積層構造を得た。現状ではおよそ100μm四方に渡って規則的に２層目が吸着した構造が得られている。 このほか、界面活性剤や高分子を添加して粒子表面を修飾し、粒子間の摩擦力を調整する手法を検討しているが、複数の粒子を橋渡しして凝集を生じる場合があり、濃度条件などを改善する必要がある。 また、当初は２年目以降に計画していたが、平面波展開法によるバンド構造の計算を開始した。単層ダイヤモンドのフォトニックバンドの周波数域と粒径、屈折率の関係について、予備的な結果を得た。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2018/04 -2022/03 
    Author : Okuzono Tohru
     
    A mechanism of diffusiophoresis with chemical reaction on a charged colloidal particle has been proposed. A theoretical model that describes the dynamics of a colloidal particle and surrounding weak electrolyte solutions has been constructed. It has been shown theoretically and numerically that the phoretic motion emerges as a response to the concentration gradient of the electrolyte. It has also been shown that the symmetry breaking of the surface charge distribution due to concentration gradients generates the force which leads to the directional motion of the particle. In a system with no electrolyte concentration gradient, a constant velocity applied to the particles results in an electrostatic force in the direction of that velocity, which reduces the apparent viscosity.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2018/04 -2021/03 
    Author : Toyotama akiko
     
    Colloidal systems have been widely studied as a crystallization model for atomic systems. However, the distinction between a universal phenomenon that can be modeled with colloids and a phenomenon peculiar to colloids that is not found in atomic systems is not always be clear. Here, we studied using a depletion-attracting colloidal system in which attractive force acts between colloidal particles with coexistence of polymer. In the system, the interaction is completely opposite (attractive or repulsive) on the presence or absence of depletant inside and outside the crystal structure. Then, we focused on an influence of the particle size on the crystal shape. The crystal shapes significantly varied depending on the particle size. For the smaller particles, the crystals were more significantly facetted, while larger particles formed less ordered aggregates. The observed change in the crystal phase was explainable in terms of decreases in attraction energy on increasing the particle size.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2017/04 -2020/03 
    Author : Yamanaka Junpei
     
    Assemblies of small numbers of colloidal particles (colloidal clusters) have attracted considerable attention as (i) models to study atomic and molecular clusters, and (ii) structural units for higher order structure. Particularly, regular tetrahedral clusters are of interest, because they are units of diamond lattices, which act as perfect photonic crystals. Thus far, we have studied the colloidal clustering via Coulomb attraction between oppositely charged colloidal particles. However, frictional forces acting between the particles prevented formation of regular tetrahedral clusters with a good symmetry. Here, we tuned the frictional force by tuning the magnitude of Coulomb force. The optimum conditions to form the regular clusters were examined. Base on the present results, the space experiment on colloidal clusters will be performed in the International Space Station in 2020.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2012/04 -2015/03 
    Author : YAMANAKA Junpei; OKUZONO Tohru; TOYOTAMA Akiko
     
    We examined clustering of oppositely charged binary colloidal particles. Optimum conditions were examined for the formations of tetrahedral clusters (particle size ratio, concentration ratio, charge number, etc). We also found that clustering of polystyrene (PS) and silica particles, both of which were negatively charged, could be controlled by additions of cationic surfactant cetylpyridinium chloride (CPC); Because of the absorption of the CPC molecules, the charge number of the PS and silica particles decreased with increasing CPC concentration (Csurf) and inverted to be positive after passing through the isoelectric point (Csurf = Ciep). The hydrophobic PS particles had much lower Ciep than that of hydrophilic silica particles. When Csurf was in the region between their Ciep’s, the PS and silica particles were charged oppositely, resulted in the clustering. Constructions of higher organizations of clusters are in progress.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2006 -2010 
    Author : DOI Masao; OKUZONO Tohru; YAMAGUCHI Tetsuo
     
    We have studied drying processes of polymer solutions on solid substrates, theoretically and experimentally, focusing on the mechanism of formation of the thin films, and prediction and control of the film shape. We have found a criterion on the formation of a thin gel-like layer on the surface of the solution, taking the elastic effect on the evaporation rate of the solvent into consideration. We have also found the initial condition dependencies of the shape of films and that the vapor distribution in air affects the shaping of deposit. We have proposed some methods for controlling shape of the film made by drying.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2006 -2010 
    Author : OHTA Takao
     
    In order to establish a new research field, the management group of Grant-in-Aid for Scientific Research on Priority Area "Creation of non-equilibrium soft matter physics: Structure and dynamics of mesoscopic systems" has been responsible for conducting four subgroups of the network project, i.e., "Molecular dynamics in structure-forming dense polymer systems", "Dynamics of mesoscopic structural transitions", "Dynamics of non-equilibrium structure", and "Theories and modeling". The public participation research which consisted of more than 50 groups has been led by the management group as well. For the purpose of promoting the network activity, the management group organized various kinds of meetings, symposiums, and workshops. The management group also kept the website of the network and prepared several reports.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2006 -2009 
    Author : OKUZONO Tohru
     
    The condition that a skin phase appears at the free surface of polymer solution in the drying process has been clarified theoretically. A theoretical expression for the evaporation rate including the elastic effect due to gelation has been obtained. A simple model has been proposed which describes drying processes of polymer droplets on a solid substrate. This model enables a theoretical prediction concerning the shape of polymer film deposited after drying. Numerical simulations of multi-droplet systems have been performed. The results show the existence of interference effects among the droplets.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2001 -2003 
    Author : OHTA Takao; NONOMURA Makiko; SAKAMOTO Kunimochi; MIMURA Masayasu; IMAI Masayuki; KOBAYASI Ryo
     
    We have carried out theoretical analysis and development of numerical method for studying various macroscopic and microscopic pattern formation in material sciences. In particular, we have investigated both numerically and analytically (1) structural transitions of mesophases in block copolymer melts (2) ordering dynamics of charged colloidal particles (3) dynamics of grain boundaries (4) domains dynamics of reactive phase separating systems and (5) formation of bacteria colony with chemotacsis. Some of these works have been performed in collaboration with experimentalists. Together with these studies, we have also developed fundamental theories of interface/grain boundary dynamics by means of singular perturbation and reduction method.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2001 -2003 
    Author : OHTA Takao; NONOMUARA Makiko
     
    We have carried out theoretical analysis and numerical simulations of mesoscopic domain formation and its kinetics in block copolymers. Phase separation competing with chemical reactions in also studied. In this case, periodic domain structures undergo a coherent propagation The subjects which we have investigated are listed as follows (1)structural transitions of mesophases in block copolymer melts. We have applied the mode expansion method to study the kinetics of transitions which involve so called gyroid structure (2)ordering dynamics of rod-coil copolymers where the elastic interaction in rod-rich domains plays a crucial role. (3)domains dynamics of reactive phase separating system, in which a Hopf bifurcation appears by changing the parameters. As a result, coherent motion of periodic domains emerges. This is the first step of the fusion of physics of soft materials and physics for from equilibrium.
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2001 -2002 
    Author : 奥薗 透
     
    3成分の化学反応系における相分離現象を記述するモデルを提案し、それに基づく数値シミュレーションを行った。このモデルは、相分離における自己組織構造が伝搬する最も簡単かつ本質を捉えたモデルであると考えられ、有限波数でHopf分岐を示すことが特徴である。このモデルに対する2次元のシミュレーションを行った結果、進行するラメラ構造および進行するヘキサゴナル構造が現れることが示された。また、進行するラメラ構造および進行するヘキサゴナル構造の出現は、それぞれ超臨界および亜臨界の分岐現象であることが数値的に明らかとなった。 進行するラメラ構造に関して、分岐点近傍において、モデル方程式から逓減摂動法により、振幅方程式を導出した。この振幅方程式の進行波解の安定性解析を行うことにより、進行波は安定に存在し得るが、定在波は安定に存在し得ないことが示された。 このモデルに含まれるパラメータのひとつ(化学反応速度定数)を外部から時間的に振動させるシミュレーションも行った。その結果、Hopf分岐曲線とTuring分岐曲線が交わる点の近傍で、ラメラおよびヘキサゴナル構造をもった定在波が存在することが示された。これらの動的構造は外部から振動させるときの振動数などの外部パラメータによって変化し、時間的に不規則な動的構造を示すパラメータ領域が存在することがわかった。また、一様振動解の線形安定性解析により、それらのシミュレーション結果の一部を説明することができた。
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2000 -2001 
    Author : 久保 泉; 宮村 修; 鈴木 孝至; 伊澤 義雄; 山西 正道; 奥園 透; 高橋 徹; 久保 泉
     
    量子原理に基づく情報処理の研究を進めるにあたり、我々は二つの側面から研究を進めてきた。一つは情報処理に必要な処理系の数理モデルであり、もう一つは物理系と素子を想定しての基本的な素子動作の研究である。昨年度は数理モデルでの成果が主であったが、今年度は特に後者についてさまざまな成果が得られたので、今回はこの素子動作研究について報告する。 想定した物理系は、微小共振器中での励起子と光子との相互作用の系であり、これは通常用いられている二準位系のモデルに帰着することができる。この系の特徴は、一つは微小半導体系であるため素子としての拡張性にすぐれていること、二つめは電場を印加することによってラビ振動のスイッチングの可能性が期待できること、さらに光による制御素子であることの3つである。さらに光子と励起子との相互作用にともなうラビ振動はすでに観測されており、この系が全く非現実的であるというわけではない。以上のことからこの系に着目し、量子計算素子の可能性を調べるために、二準位系モデルを用いて数値計算を行うことで、素子の基本的動作について調べた。 数値計算の結果、一素子については、ラビ振動のスイッチング動作と時間による位相操作によって任意のユニタリー変換を構築できることがわかった。これは光を用いた素子という観点からみると非常に大きな成果だと言える。現状で調べられている光制御による素子は、位相変化が光の振動数と同程度の速さで変化するため、現在の制御技術では位相変化が速すぎて操作が非常に困難だからである。二素子に関しては、二素子がお互い励起子状態である場合にかぎりなんらかの相互作用があると考え、第一近似として双極子双極子相互作用を想定して、二準位モデルに組み込んだ。その結果、基本的なCNOT動作をすることがわかった。さらにデモンストレーションとして、グローバーの検索アルゴリズムを実行させ、基本的な動作を確認することもできた。このように素子の基本動作と制御を明らかにしたことは、これらの動作や操作を認知処理系に組み込んだ具体的な処理系のモデルを構築するにあたって、最初の足がかりとなるものである。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 1997 -1999 
    Author : MIURA Masayasu; SAKAMOTO Kunimochi; FUNAKI Naohisa; OHTA Takao; KIMURA Masato; OKUZONO Tohru
     
    Towards mathematical understanding of melting, solidification and growth processes in material sciences, we have carried theoretical research from experiments, modeling and complementarily computer analysis. Since the head investigator had moved from the university of Tokyo to Hiroshima University at the second year of the research term, some investigators had to he altered from the original members but there was no trouble to carry out the research plan. Mimura has mainly studied pattern formation arising in nonlinear non equilibrium systems. In particular, has investigated dendritic patterns in biological and chemical systems, in order to reveal the universality in mechanism of such patterns in natural sciences. Ohta has studied dynamics of micro phase separation, as the basic theory in polymer science. Ishikawa has experimentally studied dendritic growth in material process and in particular, and has studied the effect of micro gravity on growth of colloid crystal. Oharu has developed nonlinear semi group theory to extend basic theory of free boundary problems. Funaki has studied interfacial dynamics from probabilistic approach. Matano, Yanagida and Kimura have investigated analytically and numerically mean curvature equations which describe interfaces. Yamada and Kusano have developed numerical methods to solve reaction-diffusion systems on a sphere. Tsujikawa and Mimura has studied growth process in biological systems by using singular limit methods. Sakamoto has developed singular perturbation methods and established the internal layer theory in higher dimensions. Onda has made fractalization of the surface of shapes and has obtained super water -repellent surfaces from theoretic and experimenrtal standing points. Ishimura has analyzed spiral patterns which arises in growth process in materials by using curvature flow theory. Okuzono has analyzed dynamics of two phase flow in droplet dissipative systems. Ueyama has given theoretical understanding of self-replication process in reaction-diffusion systems by using computer aided analysis. The above results have been reported in several conferences inside and outside of Japan. Most of them were talked at the Applied Mathematics Meeting in Japan which is held every year and were published in their proceedings.
  • 弱電解質の拡散によって駆動される荷電コロイドのダイナミクス
    名古屋市立大学：
    Author : 奥薗 透; 山中淳平

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