• 日時:2023年2月21日(火)16:00-
    講師:Armand Barbot (京都大学大学院 情報学研究科)
    題目:Study of plasticity in amorphous and crystalline materials using atomic scale simulations

    要旨: This seminar will focus on two main topics: (a) the study of plasticity and shear bands in metallic glasses, and (b) the multi-scale modeling of plasticity in crystalline materials using machine learning algorithms. (a) In a first part, we will focus on the study of plasticity in metallic glasses. The understanding of plasticity in metallic glasses is nowadays a very active research field. Produced for the first time in the sixties, metallic glasses are promising materials thanks to their very high yield strength. However, they also have the defect of being brittle. This high brittleness is explained by the formation of shear bands in which plasticity concentrates in the first stage of the deformation. Using atomic simulations and a new method developed to measure the local hardness of these simulated materials, we will study the importance of rejuvenation in the formation of shear bands and in particular the influence of the preparation and size of the system. We will also look at the evolution of the shear band width with the applied stress and compare it with an analytical model. (b) In the second part, we will focus on the nucleation of thermally activated heterogeneous dislocations. The nucleation of thermally activated heterogeneous dislocations is the dominant mechanism of plasticity for crystals smaller than 100-200nm such as metallic or semiconductor nano-pillars or nano-films. Nucleation is thus an essential phenomenon for the understanding and control of mechanical properties at the nanoscale, and thus, for example, to allow the miniaturization of electronic components subjected to high stress and temperature. This mechanism also plays an important role in the understanding and modeling of crack propagation, as nucleations blunt the crack tips, thus slowing down their propagation speed. Although this phenomenon can be reproduced in numerical simulations at the atomic scale, its implementation in Discrete Dislocation Dynamics (DDD) simulations, allowing to simulate materials on larger size and time scales, is still missing. We propose here approaches based on the use of machine learning algorithms to allow the implementation of these nucleations in DDD simulations based on results obtained with atomic scale simulations.
  • 日時:2023年1月5日(木)16:00-
    講師:John Russo (Sapienza Università di Roma, Italy)
    題目:Water is a (half) empty liquid
    要旨:It is becoming increasingly clear that water’s structure has enough empty space to accommodate a second liquid at high pressure.

    Exploiting this analogy, we classify water together with a larger group of liquids, aptly named Empty Liquids, whose constituents arrange in a random network through reversible bonds [1]. These bonds can be physically realized with a variety of interactions, such as hydrogen bonding, lock-and-key interactions, DNA base pairing, hydrophobic, dipolar, and even entropic interactions. Materials that fall in the category of empty liquids go from patterned colloidal particles, clays, DNA wireframe origamis, all the way down to atoms, like silicon.
    In this seminar we make the case that water is a Half-Empty liquid, which, on top of the typical empty liquid’s behaviour, can display complex properties such as thermodynamic and dynamic anomalies, the possibility of liquid–liquid phase transitions, and the crystallization of open crystalline structures. Finally, we will try to answer the age-old question whether amorphous glasses are half-empty too [2].
    [1] J. Russo, F. Leoni, F. Martelli, F. Sciortino, Rep. Prog. Phys. 85, 016601 (2022)
    [2] F. Martelli, F. Leoni, F. Sciortino, J. Russo, J. Chem. Phys. 153, 104503 (2020)
  • 日時:2022年12月20日(火)13:00-
    講師:Dr. Yukio Kajihara (Hiroshima Univ.)
    題目:Understanding the specific heat of liquids by focusing on critical fluctuations

    要旨:How to understand specific heat of liquids ? The equipartition theorem is the main principle regarding the specific heat of materials. The isochoric specific heats Cv are, 1.5R (R: gas constant) for monoatomic gases, 2.5R for diatomic molecular gases, and 3R for elemental solids (Dulong-Petit law): The concept of "degree of freedom" can universally interpret the specific heat of gases and solids irrespective of materials. What about liquids, then ? Liquids have higher specific heats than gases and solids, which is explained by the concept that they can have various "configurations" and thus have an extra degree of freedom compared to solids and gases. However, to be honest, it is unclear what kind of "configuration" contributes to specific heat and to what extent. Meanwhile, when we look at the wide range of temperature-pressure dependence of Cv of liquid (fluid) water [1], we notice a simple fact: Two distinct rises are seen and they characterize the overall feature of Cv of water. The one in the high temperature region is topped by the critical point of the liquid-gas phase transition (LGT), and is clearly due to the critical fluctuation of LGT. The fact that critical fluctuation increase the specific heat is a fundamental concept described in textbooks. The other one in the low-temperature region extends to the top of the low-pressure supercooled region, and it is reasonable to recognize that it is due to the critical fluctuation associated with the liquid-liquid phase transition (LLT), which is proposed to have a critical point in the supercooled region. In other words, it is possible to construct a framework for interpreting the specific heat of liquids by considering the critical fluctuations associated with these two phase transitions as the entity of "configuration".
    In the talk, I will introduce the detail of this framework while showing our experimental results on "dynamical fluctuations" of water [2]. Critical fluctuation of LLT differs from that of LGT in several respects, and it is important to discuss them in an organized manner. The final goal of the framework proposed here is to develop a unified concept of disordered materials, including glass transition liquids. I would be happy to share this final goal with you !
    [1] W. Wagner and A. Pruss, J. Phys. Chem. Ref. Data 31, 387 (2002)
    [2] Y. Kajihara et al., arXiv 2111.06589
  • 日時:2022年10月6日(木)13:30-
    講師:Anupam Sengupta (the University Luxembough)
    題目: Microbial Active Matter
    要旨:Understanding how microbes interface, exchange and communicate with their local surroundings is central to the grand quest for a theory of microbial ecology. From simple to complex fluids, from compliant to rigid environments, microbes inhabit plethora of dynamic settings spanning vastly different structures, internal energies, and interacting cues. Currently we lack a biophysical framework that could explain, generalize, and crucially, predict the if-s, the how-s, and the why-s of the microbe-environment feedbacks. Research in our lab aims to fill this gap by interfacing soft and active matter physics with microbiology and genetic engineering, often with generous support of 3D microfabrication, automation, quantitative imaging and machine learning tools. Using vignettes from our recent works in bacterial and phytoplankton systems [1-4],we will see microbes – under ecologically relevant settings – in an active matter framework, and discuss their individual and collective traits (behavior and physiology) in the context of microbial adaptation to changing environments. I will highlight the generality of our results across populations and taxa, touching upon concepts of emergent intelligence associated with the active microbial matter at collective scales. I will conclude by showcasing some of our recent efforts to leverage the microbes- mechanics-materials nexus in understanding functions of microbes associated with specific cancer types, and more broadly, to harness the biophysical feedbacks for the next generation of bioremediation and diagnostic tools.
    [1] Sengupta, Carrara, & Stocker, Nature 543, 555-558, 2017 [2] Sengupta, Dhar, Danza, Ghoshal, Müller, Kakavand, Science Advances (in press) [3] You, Pearce, Sengupta, Giomi, Physical Review X 8, 031065, 2018 [4] Sengupta, Frontiers in Physics 8, 2020 [5] Dhar, Thai, Ghoshal, Giomi, & Sengupta, Nature Physics 18, 945-951, 2022


  • 日時:2019年5月27日(月)10:30-
    講師:Armand Barbot (Ecole Normale Superieure, France)
      題目: Characterization of shear bands and plasticity in model glasses at the atomic scale

  • 日時:2018年9月18日(火)13:30-
    講師:藪中俊介氏 (京都大学 福井謙一記念研究センター)  
    題目: 二元混合系中の選択的溶媒和効果を持つ塩で構成された電気二重層:

  • 日時:2018年6月12日(火)13:30-
    講師:藤谷洋平氏 (慶応大学)
      題目: Drag coefficient of a circular liquid domain in a flat fluid
    membrane a bit close to the demixing critical point

  • 日時:2017年9月8日(金)14:00-
    講師:Ram Adar (School of Physics and Astronomy, Tel Aviv University, Israel)
      題目: Bjerrum pairs in ionic solutions: a Poisson-Boltzmann approach

  • 日時:2017年4月26日(水)16:00-
    場所:基礎物理学研究所 研究棟・講義室 K206 (場所に注意)
    講師:Subhadeep Roy (Earthquake Research Institute, University of Tokyo)
      題目: Fracture in Different Scales: A Statistical Mechanical Approach

  • 日時:2017年2月21日(火)13:30-
    講師: 高江 恭平氏 (東京大学)
      題目:Ferroelectric glass of spheroidal dipoles with impurities

  • 日時:2016年12月7日(水)15:00-
    場所:基礎物理学研究所 研究棟・講義室 K206 (場所に注意)
    講師:Anael Lemaitre (NAVIER, URM 8205, Ecole des Ponts, IFSTTAR, CNRS, UPE, France)
      題目:Anomalous phonon scattering and elastic correlations in amorphous solids

  • 日時:2016年11月28日(月)13:30-
    講師:Lee, Kuang-Wu (Friedrich-Alexander-University, Erlangen, Germany)
      題目:Mesoscopic Simulation of Nematic Liquid Crystals in Microfluidics

  • 日時:2016年9月29日(木)16:00-
    講師:植松 祐輝氏 (九州大学理学研究院化学部門)  

  • 日時:2016年3月15日(火)13:00-
    講師:Tatsuya Ishiyama (石山 達也氏) (Graduate School of Science and Engineering, University of Toyama )  
    題目:Molecular Dynamics Study of Structure and Spectroscopy at Liquid Interface

  • 日時:2015年12月8日(火)13:00-
    講師:Itsuo Hanasaki (花崎 逸雄氏) (Tokyo University of Agriculture and Technology)  
    題目:Applied statisitical mechanics for engineering: from molecular dynamics and coarse-graining
    to big data analysis of fluctuation measurements and single-particle characterization

  • 日時:2015年11月17日(火)13:00-
    講師:Tsuyoshi Yamaguchi (山口 毅氏) (Nagoya University)
      題目:Theory on dynamics of electrolyte solutions: Interplay between dynamics of bound pairs and ionic atmosphere

  • 日時:2015年11月13日(金)17:00-
    講師:Kyohei Takae (高江 恭平氏) (University of Tokyo) 
    題目:Water in a Capacitor: Structure, Fluctuation, and Response

  • 日時:2015年6月16日(火)13:00-
    講師:Takuya Sugimoto (Graduate School of Life and Environmental Sciences, University of Tsukuba) 
    題目:Aggregation Rates of Charged Colloidal Particles in a Couette Flow: Trajectory Analysis with Non-linear Poisson-Boltzmann Solution

  • 日時:2015年6月2日(火)13:30
    講師:Hayato Shiba (芝 隼人)(The University of Tokyo) 
    題目:Membrane simulation - elasticity, surface tension, and some applications

  • 日時:2015年1月20日(火)15:00
    講師:Toshiki Mima (美馬 俊喜氏)(The University of Tokyo) 
    題目:Molecular dynamics simulation of fluids in nanopores

  • 日時:2014年11月18日(火)10:30
    講師:Jack F. Douglas (National Institute of Standards and Technology)
    題目:Cooperative Motion and Structural Relaxation in Glass-Forming Materials

  • 日時:2014年11月11日(火)13:00
    講師:Hiroaki Yoshida (Toyota Central R&D Labs.)
    題目:Analysis of electrokinetic transports of nano-confined electrolyte solutions by means of the molecular dynamics simulations

  • 日時:2014年8月27日(水)13:30
    講師:Anael Lemaitre (Laboratoire Navier (UMR 8205), Universite Paris-Est, France)
    題目:Structural relaxation is a scale-free process

  • 日時:2014年5月14日(水)15:30
    講師:Mohammad Reza Mozaffari (University of Qom, Qom, Iran )
    題目:Pair interaction between colloidal particles in nematic liquid crystal

  • 日時:2014年4月21日(月)13:30-
    講師:清水 涼太郎(東京大学生産技術研究所)

  • 日時:2014年2月12日(水)13:30-

  • 日時:2013年11月15日(月)16:00
    講師:AMiha Ravnik (Faculty of Mathematics and Physics, University of Ljubliana, Centre of Excellence NAMASTE, Slovenia)
    題目:Topological superstructure in nematic liquid crystal colloids

  • 日時:2013年4月22日(月)13:30
    講師:Dr. Flavio Romano (Department of Chemistry, University of Oxford, UK JSPS Fellowship, University of Tokyo)
    題目:OxDNA: a coarse-grained model for simulations of DNA

  • 場所:理学部5号館413号室
    講師:Jure Dobnikar (Department of Chemistry, University of Cambridge and Jozef Stefan Institute, Ljubljana, Slovenia)
    題目:Field-induced self-assembly of suspended colloidal membranes

  • 日時:2012年11月14日(水)16:00
    講師:Paddy Royall ((Bristrol University, UK)
    題目:Colloidal and metallic liquids out of equilibrium : linking structure and kinetics

  • 日時:2012年9月11日(火)14:30
    講師:Francesca Serra (イタリア ミラノ大学 9/7-12/6まで相転移に滞在)
    題目:Memory from topology: an experimental point of view

  • 日時:2012年7月12日(木)10:30
    場所:理学部5号館413号室 講師:波多野 恭弘氏 (東京大学 地震研究所)
    題目:Granular friction in a wide range of shear rates

  • 日時:7月11日(水)15:30
    講師:Nasser Mohieddin Abukhdeir (Japan Society for the Promotion of Science Visiting Fellow* National Institute of Advanced Industrial Science and Technology (AIST) Tsukuba, Ibaraki Prefecture, Japan)
    題目:Formation and Dynamics of Smectic-A Liquid Crystals

  • 日時:2012年7月10日(火)13:30
    講師:貞包 浩一朗氏 (KEK)
    題目:The shear effects on a mixture of water / organic solvent / antagonistic salt

  • 日時:2012年4月23日(月)16:00
    講師:Daniel Beysens (CEA and ESPCI, Paris, France)
    題目:Adsorption on colloids and flocculation

  • 講師:小山岳人 氏(独立行政法人海洋研究開発機構)
    場所:5号館 401号室

  • 講師:下川智嗣 准教授(金沢大学理工研究域)
    場所:5号館 401号室

  • 日時:2010年9月3日(金)午後3時-
    講師: Didier R. Long (Laboratoire Polymeres et Materiaux Avances: CNRS/Rhodia; Rhodia Reserches et Technologies, France)
    題目: Slow domains percolation in polymer melts and blends close to the glass transition: a unifying concept regarding bulk dynamics, dynamics in the vicinity of interfaces, and the physical properties of nanocomposites

  • 日時:2010年4月13日(火) 14:00〜br> 場所:理学部5号館401号室br> 講演者:川崎 猛史(相転移PD)br> 題目:ブラウン動力学法による3次元コロイド分散系のガラス転移と結晶化br>br>
  • 日時:2009年1月21日(木)15時30分-
    講師:Prof. Turab Lookman (Theoretical Division, Los Alamos National Laboratory, Los Alamos, USA)
    題目:Microstructure and glassy phenomena for ferroelastic transitions in two and three dimensions using strain pseudo-spin models

  • 日時:2009年4月21日(火)17時-
    講演者:川崎 猛史 氏 (東京大学生産技術研究所田中研D3)
    題目: 3次元コロイドガラスにおける秩序構造と動的不均一性

  • 日時:2009月3月10日(火)13時30分-
    場所:理学部5号館401号室 講演者:齋藤 国靖 氏 (京都大学基礎物理学研究所D1)
    題目: ナノクラスター衝突のぬれ転移

  • 日時:2008年9月12日(金)16:00-
    講演者:貞包 浩一郎 氏 (吉川研究室D2)
    題目: 溶媒和効果による水/有機溶媒混合系の長距離秩序

  • 日時:2008年9月12日(金)
    講演者:井口 奈津希 氏 (吉川研究室M2)