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Home > Research > Talks & Conferences > Talks Given at LIPhy

Invited Talks

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These talks are given by invited speakers at LIPhy. The intended audience is the whole LIPhy. A large general introduction intended for non-specialist is usually provided.

Typical talk duration is around one hour and includes about 15 mn of questions. The talks are scheduled usually every Monday at 2PM. The place is at the conference room, second floor.

Access to the lab can be obtained by calling Nadine D’Andréa or Chantal Reignier through the intercom at the main entrance.

Agenda

  • Monday 25 January 2016 14:00-15:30 - Christophe Le Clainche - Institute for Integrative Biology of the Cell (I2BC), B3S, CNRS, Gif-sur-Yvette

    Regulation of Actin Assembly and Mechanotransduction in Cell-Matrix Adhesion Complexes: A Biochemical Study of the Talin-Vinculin Complex

    Résumé : Cell migration is involved in many physiological and pathological processes. Force is produced by the growth and the contraction of the actin cytoskeleton. To produce force, these actin networks must be anchored to the extracellular matrix (ECM) by adhesion complexes. These structures contain transmembrane integrins that mechanically couple the ECM to the intracellular actin cytoskeleton via actin binding proteins (ABPs). This system acts as a molecular clutch that controls force transmission across adhesion complexes. This molecular clutch is a complex interface made of multiple layers of regulated protein-protein interactions. The multiple activities of the ABPs present in these structures play a critical role in the dynamics of this interface. In addition to the control of actin filament binding and polymerization, these proteins sense and respond to the force applied by the actomyosin cytoskeleton to adjust the anchoring strength.
    Our goal is to determine the molecular mechanisms by which these ABPs cooperate to control the mechanical coupling between the actin cytoskeleton and cell-matrix adhesion.
    To study these ABPs, our laboratory combines the measurement of actin polymerisation kinetics in fluorescence spectroscopy, single actin filament observations in TIRF microscopy and the reconstitution of actin-based mechanosensitive processes on micropatterned surfaces.
    Our results showed that vinculin controls actin filament elongation. More recent results revealed that talin also regulates actin polymerisation in response to integrin binding (unpublished data). In addition, we have developed a microscopy assay with pure proteins in which the self-assembly of cables, made of actin, myosin and alpha-actinin, controls the association of vinculin to a talin-micropatterned surface in a reversible manner. This in vitro reconstitution revealed the mechanism by which a key mechanosensitive molecular switch senses and controls the connection between adhesion complexes and the actomyosin cytoskeleton.



    contact: Jocelyn Etienne

    Lieu : LIPhy, conference room - 140 Avenue de la Physique 38402 Saint Martin d’Hères


  • Monday 8 February 2016 14:00-15:30 - Andreas HEUER - Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster, Münster, Germany

    Understanding the Properties of Supercooled Liquids and Glasses in Terms of Their Potential Energy Landscape

    Résumé : Glass-forming systems display many fascinating properties such as the dramatic increase of relaxation time upon cooling or the presence of dynamic heterogeneities. Furthermore, upon strong external perturbations, as applied in microrheological or shear experiments, a characteristic response is observed. I start with a short review of some of these key features.
    Then I will introduce the concept of the potential energy landscape (PEL) which constitutes a general theoretical framework to capture many of these effects and to elucidate their underlying physical mechanisms. A few interesting applications will be discussed. First, it is shown how several dynamic equilibrium properties can be expressed in terms of the distribution of minima and barriers of the PEL as well as an elastic coupling between different regions of the supercooled liquid. Second, the thermodynamic as well as dynamic effects, observed for the microrheological perturbation, can be fully understood in terms of an effective temperature. This observation is a consequence of the statistical properties of the underlying PEL. The resulting scaling properties hold up to temperature significantly below the glass transition temperature. Third, the outcome of shear simulations for glasses can be related to the hopping dynamics in an appropriately defined PEL.



    contact: Kirsten Martens

    Lieu : LIPhy, conference room - 140 Avenue de la Physique 38402 Saint Martin d’Hères


  • Friday 11 March 2016 11:00-12:00 - Sébastien Balme - Institut Européen des Membranes, Université de Montpellier II

    Nanopores uniques fonctionnalisés pour la réalisation de diode-ioniques, nanovalves et la capture de molécule unique

    Résumé : La fonctionnalisation chimique des nanopores dit « solid-state » ouvre des perspectives très intéressantes. En effet, elle rend possible la synthèse nanopore unique permettant de mimer les canaux biologiques mais aussi de proposer un control idéal pour des études fondamentales du transport des électrolytes simples (ion), complexes (ADN, Protéine, poly-électrolyte) ou de nanoparticules. L’objectif de cette présentation sera de présenter mes activités relevant de cette thématique. Nous discuterons de la conception de nanopores unique, leurs designs et leurs fonctionnalisations afin de contrôler précisément leurs propriétés (diamètre, surface, sélectivité, activité…). Dans un premier temps, il sera discuté du transport d’électrolyte simple dans un nanopore non chargé et hydrophobe. Ensuite, il sera développé, des travaux sur la conception de diodes ioniques modifiable par l’adsorption de poly-électrolyte ou la capture de protéines ainsi que de nanovalves stimulables par le pH. Enfin, seront abordé des études visant à comprendre l’influence de la surface des nanopores sur la capture et le transport de biomacromolécules (ADN, protéines) et nanoparticules. Ces dernières études sont cruciales pour le développement de compteur Coulter nanométrique.



    contact: Lionel Bureau

    Lieu : LIPhy, conference room - 140 Avenue de la Physique 38402 Saint Martin d’Hères


  • Monday 14 March 2016 14:00-15:30 - Valessa Barbier - Université Paris-Est de Créteil

    A New Polymeric Scaffold for Biomimetic Applications

    Résumé : In the framework of research projects aimed at designing polymers with biomimetic features, we have developed a new polymeric scaffold, dubbed OCD for Oligomers from Cyclopropane Dicarboxylates monomers. They have geminal substituants located on every third carbon along a polymethylene backbone and are obtained by Anionic Ring Opening Polymerization using a phosphazene base to generate in situ the polymerisation initiator.
    Biomimetic nano-objets have been designed such as synthetic membranes made by the self-assembly of amphiphilic liquid crystal (LC) PEG-OCD block copolymers. Crown-ethers substituted OCDs have also been developed as potential biological membrane permeabilizers. Cation-selective pores within model bilipidic membranes, as well as an anti-proliferative effect towards cancer cells have been observed. More recently, a new family of glycopolymers have been synthesized by post-modification of an OCD scaffold using the thiol-ene radical addition and their interactions with carbohydrate-binding proteins have been investigated.
    To conclude, the use of OCDs to design biomimetic surfaces will be discussed.



    contact: Delphine Débarre

    Lieu : LIPhy, conference room - 140 Avenue de la Physique 38402 Saint Martin d’Hères


  • Monday 21 March 2016 14:00-15:30 - Andreea PASC - SRSMC, Nancy

    Bioactive Amphiphiles and Materials: Synthesis, Physicochemical Properties, and Applications

    Résumé : Molecularly organized systems (i.e. monolayers, vesicles, gels, solid lipid nanoparticles) are presented as colloidal tools to structure and functionalize inorganic surfaces or to design hybrid materials. Three examples will be detailed:
    - functional microdomains embedded in supported lipid membranes to study the dynamic adhesion of macrophages in microfluidic devices.
    - biomimetic supported silica membranes and engineering of self-standing polymeric membranes for ion conduction
    - stimuli-responsive colloids templating silica materials for the delivery of drugs, enzymes or bacteria.
    The seminar will be given in French



    contact: Lionel Bureau

    Lieu : LIPhy, conference room - 140 Avenue de la Physique 38402 Saint Martin d’Hères


  • Monday 4 April 2016 14:00-15:30 - Sofia BIAGI - Dipartimento di Fisica, Sapienza-Universita di Roma, Italy and LIPhy

    Simulations of Dense Polymer Brushes: Zooming in the Mesoscale

    Résumé : Polymer brushes are versatile media: they are used to regulate adhesion properties of surfaces, for colloid stabilization, and since the recent discovery that the inner surface of various mammalian organs is coated by densely grafted macromolecules (the lumen of blood vessels, for example), the investigation is targeted also to biomedical applications.
    By means of a coarse-graining method (Dissipative Particle Dynamics) we simulate the mesoscale dynamics of a flexible homodisperse polymer brush subdue to a simple liquid parabolic flow in slit pore geometry. We report that the system displays flow inversion at the brush interface and we associate such phenomenon to collective polymer dynamics: a wave propagating over the brush surface. Moreover, a striking similarity is observed between our passive polymer brush and active microswimmers (precisely, the Taylor’s swimmer).



    contact: Chaouqi Misbah

    Lieu : LIPhy, conference room - 140 Avenue de la Physique 38402 Saint Martin d’Hères


  • Monday 25 April 2016 14:00-15:30 - Fabien MONTEL - MSC Paris/ENS Lyon, France

    Transport Through the Nuclear Pore Complex: Crowding and Plasticity

    Résumé : The nuclear pore complex is the unique gateway between the nucleus and the cytoplasm of the cells. It ensures both directional and selective transport of nucleic acids and proteins. Its detailed mechanism is still highly debated and in particular its ability to react to very different environments. Using two different single-molecule techniques we studied the influence of external control parameters (molecular crowding and development stage) on its structure and dynamics. We used a near field optics technique to quantify the effect of the molecular crowding of the pore on the transport through native and mimetic pores. De Gennes-Brochard model for polymer injection is extended and the critical pressure for cargo translocation is measured to extract the free energy of translocation in different conditions. Our results obtained using optical super-resolution indicate that development impacts the internal diameter of the nuclear pore complex. This effect can be recapitulated by a change in transcriptional activity. We also observe and quantify a 2D phase transition from a dense and amorphous structure to the large scale crystallization of the pores on a square lattice during development.



    contact: Aurélie Dupont

    Lieu : LIPhy, conference room - 140 Avenue de la Physique 38402 Saint Martin d’Hères


  • Monday 9 May 2016 14:00-15:30 - François-Xavier COUDERT - CNRS & Chimie ParisTech

    Molecular Simulation of Soft Porous Crystals

    Résumé : A large number of Metal–Organic Frameworks (MOFs) exhibit deformations of large amplitude induced by physical or chemical stimuli. These materials, termed Soft Porous Crystals, undergo swelling, pore opening/closing, and structural transitions under changes of temperature, mechanical stress, guest adsorption, electric fields, etc. They have attracted a lot of attention from materials scientists, who explore their potential practical applications (e.g. as sensors or nanoswitches) and try to engineer crystals with targeted properties.
    Our team has built a “toolbox” of theoretical approaches to shed light into these materials’ properties, and in particular to address the interplay between the phenomena of adsorption, deformation and reactivity of these materials. Such tools include molecular simulation methods and algorithms for the understanding of the mechanical and hydrothermal stability of these materials, as well as thermodynamic models to understand the adsorption-induced structural transitions, and the coadsorption and separation properties of Soft Porous Crystals. We strive to use these various methods to provide a coherent description of Soft Porous Crystals from the unit cell scale all the way to the behavior of the whole crystal.



    contact: Cyril Picard

    Lieu : LIPhy, conference room - 140 Avenue de la Physique 38402 Saint Martin d’Hères


  • Monday 30 May 2016 14:00-15:30 - Marcus Hauser - Otto Von Guericke Universität, Magdeburg, Germany

    Migratory Behaviour of Physarum Polycephalum Microplasmodia

    Résumé : The motility of amoeboid cells of the plasmodial slime mould Physarum polycephalum was studied experimentally. Analysis of their trajectories and of their mean square displacements reveal two characteristic types of behaviour. Whereas free migration of cells is observed for long time intervals (above 300 s), at short time intervals (of up to 100 s) the motility is due to changes in the cell shape induced by the peristaltic pumping of protoplasm through the cell. We observed that high propagation velocities are correlated with both, episodes of straight motion and an elongated cell shape. Furthermore, the patterns of cell thickness oscillations (that provide for the intracellular peristaltic pumping of protoplasm) also changed as a function of the propagation velocity of the cell.



    contact: Philippe Peyla

    Lieu : LIPhy, conference room - 140 Avenue de la Physique 38402 Saint Martin d’Hères


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  • Wednesday 16 December 2015 10:00-17:00 - plusieurs intervenants

    Journée speckle

    Résumé : *Erik Geissler (DLS et diffusion cohérente des X) ;
    *Romain Pierrat - ESPCI (diffusion optique simple/multiple dans les milieux désordonnés + aspects dynamiques) ;
    *Vincent Favre Niccolin - I.Néel (imagerie par diffraction cohérente des X)

    Lieu : salle de lecture


  • Wednesday 6 July 2016 08:30-18:00 -

    Workshop depinning vs yielding

  • Friday 24 June 2016 14:00-15:30 - Emanuela Del Gado - Georgetown University, Washington DC, USA

    Gelation and Densification of Cement Hydrates: A Soft Matter in Construction

    Résumé : Abstract: 5-8 % of the global human CO2 production comes from the production of cement, concrete main binder. The material strength emerges through the development, once in contact with water, of calcium-silicate-hydrate (C-S-H) gels that literally glue together the final compound. Current industrial research aims at exploring alternative and more environmentally friendly chemical compositions while enhancing rheology and mechanics, to overcome the many technological challenges and guarantee concrete standards. Identifying the fundamental mechanisms that control the gel properties at the early stages of hydration and setting is crucial, although challenging, because of far-from-equilibrium conditions, closely intertwined to the evolution of the chemical environment, that are a hallmark of cement hydration.
    I will discuss a recently developed statistical physics approach, which allows us to investigate the gel formation under the out-of-equilibrium conditions typical of cement hydration and the role of the nano-scale structure in C-S-H mechanics upon hardening. Our approach, combining Monte Carlo and Molecular Dynamics simulations, unveils for the first time how some distinctive features of the kinetics of cement hydration can be related to the nano-scale effective interactions and to the changes in the morphology of the gels. The novel emerging picture is that the changes of the physico-chemical environment, which dictate the evolution of the effective interactions, specifically favor the gel formation and its continuous densification. Our findings provide new handles to design properties of this complex material and an extensive comparison of numerical findings for the hardened paste with experiments ranging from SANS, SEM, adsorption/desorption of N2 and water to nano-indentation provide new, fundamental insights into the microscopic origin of the properties measured.
    K. Ioannidou, R.J.-M. Pellenq and E. Del Gado, Controlling local packing and growth in calcium-silicate-hydrate gels, Soft Matter 10, 1121 (2014)
    E. Del Gado, K. Ioannidou, E. Masoero, A. Baronnet, R. J.-M. Pellenq, F. J. Ulm and S. Yip, A soft matter in construction - Statistical physics approach for formation and mechanics of C—S—H gels in cement, Eur. Phys. J. - ST 223, 2285 (2014).
    K. Ioannidou, K.J. Krakowiak, M. Bauchy, C.G. Hoover, E. Masoero, S. Yip, F.-J. Ulm, P. Levitz, R.J.-M. Pellenq and E. Del Gado, The mesoscale texture of cement hydrates , PNAS 113, 2029 (2016)
    K. Ioannidou, M. Kanduc, L. Li, D. Frenkel, J. Dobnikar and E. Del Gado, The crucial effect of early-stage gelation on the mechanical properties of cement hydrates, Nature Communications (2016), to appear.



    contact: Kirsten Martens

    Lieu : LIPhy, conference room - 140 Avenue de la Physique 38402 Saint Martin d’Hères


  • Wednesday 10 November 14:00-17:30 - Nicolas Cuny

    PhD Nicolas Cuny

    Résumé : Dérivations de modèles constitutifs: de la microstructure à la rhéologie des suspensions denses molles
    Jury:

    • Madame Catherine Barentin, Professeur Université Lyon 1
    • Monsieur Ludovic Berthier, Directeur de Recherche CNRS, Université de Montpellier
    • Monsieur Michel Cloitre, Directeur de Recherche CNRS, ESPCI Paris
    • Monsieur Vincent Démery, Maître de conférence, ESPCI Paris
    • Monsieur Pierre Saramito, Directeur de Recherche CNRS, Université Grenoble-Alpes
    • Monsieur Gilles Tarjus, Directeur de Recherche CNRS, Sorbonne Université

    Lieu : Salle de conférence LIPhy


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