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Publications (en anglais)

  1. Articles scientifiques
  2. Livres
  3. Mémoires

 

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1. Articles scientifiques

  •  

    Flexoelectric fluid membrane vesicles in spherical confinement

    Niloufar Abtahi, Lila Bouzar, Nadia Saidi-Amroun, Martin Michael Müller

    Résumé     Plus d'infos

    EPL, 131(1): 18001, 2020. Cf. aussi arXiv:2006.04475.

     


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    Isometric bending requires local constraints on free edges

    Jemal Guven, Martin Michael Müller, Pablo Vázquez-Montejo

    While the shape equations describing the equilibrium of an unstretchable thin sheet that is free to bend are known, the boundary conditions that supplement these equations on free edges have remained elusive. Intuitively, unstretchability is captured by a constraint on the metric within the bulk. Naïvely one would then guess that this constraint is enough to ensure that the deformations determining the boundary conditions on these edges respect the isometry constraint. If matters were this simple, unfortunately, it would imply unbalanced torques (as well as forces) along the edge unless manifestly unphysical constraints are met by the boundary geometry. In this article, we identify the source of the problem: not only the local arc-length but also the geodesic curvature need to be constrained explicitly on all free edges. We derive the boundary conditions which follow. In contrast to conventional wisdom, there is no need to introduce boundary layers. This framework is applied to isolated conical defects, both with deficit as well, but more briefly, as surplus angles. Using these boundary conditions, we show that the lateral tension within a circular cone of fixed radius is equal but opposite to the radial compression, and independent of the deficit angle itself. We proceed to examine the effect of an oblique outer edge on this cone perturbatively demonstrating that both the correction to the geometry as well as the stress distribution in the cone kicks in at second order in the eccentricity of the edge.

     Fermer     Plus d'infos

    Math. Mech. Solids, 24: 4051, 2019. Cf. aussi arXiv:1904.05855.

     


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    Helical Superstructure of Intermediate Filaments

    Lila Bouzar, Martin Michael Müller, René Messina, Bernd Nöding, Sarah Köster, Hervé Mohrbach, Igor M. Kulić

    Résumé     Plus d'infos

    Phys. Rev. Lett., 122: 098101, 2019. Cf. aussi arXiv:1803.04691.

     


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    Vesicle dynamics in confined steady and harmonically modulated Poiseuille flows

    Zakaria Boujja, Chaouqi Misbah, Hamid Ez-Zahraouy, Abdelilah Benyoussef, Thomas John, Christian Wagner, Martin Michael Müller

    We present a numerical study of the time-dependent motion of a membrane vesicle in a channel under an imposed flow. In a Poiseuille flow the shape of the vesicle depends on the flow strength, the mechanical properties of the membrane, and the width of the channel. In a wide parameter region, the emerging snaking shape shows an oscillatory motion like a swimmer flagella even though the flow is stationary. We quantify this behavior by the amplitude and frequency of the oscillations of the vesicle's center of mass. The influence of an amplitude modulation of the imposed flow on the dynamics and shape of the snaking vesicle is also investigated. We find that this modulation---when sufficiently small---induces a modulation in amplitude and frequency of the center of mass of the snaking vesicle. For large modulation amplitudes transitions to static shapes are observed.

     Fermer     

    Phys. Rev. E, 98: 043111, 2018. Cf. aussi arXiv:1810.04500.

     


  •  

    Confining a fluid membrane vesicle of toroidal topology in an adhesive hard sphere

    Lila Bouzar, Ferhat Menas, Martin Michael Müller

    We discuss how the equilibrium shapes of a confined toroidal fluid membrane vesicle change when an adhesion between membrane and confining sphere is taken into account. The case without adhesion was studied in Ref. [1]. Different types of solution were found and assembled in a phase diagram as a function of area and reduced volume of the membrane. Depending on the degree of confinement the vesicle is either free, in contact along a circle (contact-circle solutions) or on a surface (contact-area solutions). All solutions without adhesion are up-down symmetric. When the container is adhesive, the phase diagram is altered and new kinds of solution without up-down symmetry are found. For increasing values of adhesion the region of contact-circle solutions shrinks until it vanishes completely from the phase diagram.

     Fermer     Plus d'infos

    IOP Conf. Series: MSE, 186: 012021, 2017.

     


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    Squeezed helical elastica

    Lila Bouzar, Martin Michael Müller, Pierre Gosselin, Igor M. Kulić, Hervé Mohrbach

    Résumé     Plus d'infos

    Eur. Phys. J. E, 39: 114, 2016. Cf. aussi arXiv:1606.03611.

     


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    How bio-filaments twist membranes

    Julien Fierling, Albert Johner, Igor M. Kulić, Hervé Mohrbach, Martin Michael Müller

    Résumé     

    Soft Matter, 12: 5747, 2016.

     


  •  

    Toroidal membrane vesicles in spherical confinement

    Lila Bouzar, Ferhat Menas, Martin Michael Müller

    We investigate the morphology of a toroidal fluid membrane vesicle confined inside a spherical container. The equilibrium shapes are assembled in a geometrical phase diagram as a function of scaled area and reduced volume of the membrane. For small area the vesicle can adopt its free form. When increasing the area, the membrane cannot avoid contact and touches the confining sphere along a circular contact line, which extends to a zone of contact for higher area. The elastic energies of the equilibrium shapes are compared to those of their confined counterparts of spherical topology to predict under which conditions a topology change is favored energetically.

     Fermer     Plus d'infos

    Phys. Rev. E, 92: 032721, 2015. Cf. aussi arXiv:1509.00765.

     


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    Non-linear buckling and symmetry breaking of a soft elastic sheet sliding on a cylindrical substrate

    Norbert Stoop, Martin Michael Müller

    Résumé     Plus d'infos

    Int. J. Non-Linear Mech., 75: 115, 2015. Cf. aussi arXiv:1503.05030.

     


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    Crunching Biofilament Rings

    Julien Fierling, Martin Michael Müller, Hervé Mohrbach, Albert Johner, Igor M. Kulić

    We discuss a curious example for the collective mechanical behavior of coupled non-linear monomer units entrapped in a circular filament. Within a simple model we elucidate how multistability of monomer units and exponentially large degeneracy of the filament's ground state emerge as a collective feature of the closed filament. Surprisingly, increasing the monomer frustration, i.e., the bending prestrain within the circular filament, leads to a conformational softening of the system. The phenomenon, that we term polymorphic crunching, is discussed and applied to a possible scenario for membrane tube deformation by switchable dynamin or FtsZ filaments. We find an important role of cooperative inter-unit interaction for efficient ring induced membrane fission.

     Fermer     Plus d'infos

    Europhys. Lett., 107(6): 68002, 2014. Cf. aussi arXiv:1408.6787.

     


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    Confotronic dynamics of tubular filaments

    Osman Kahraman, Hervé Mohrbach, Martin Michael Müller, Igor M. Kulić

    Résumé     Plus d'infos

    Soft Matter, 10(16): pp. 2836-2847, 2014. Cf. aussi arXiv:1312.3106.

     


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    Whirling skirts and rotating cones

    Jemal Guven, J. A. Hanna, Martin Michael Müller

    Steady, dihedrally symmetric patterns with sharp peaks may be observed on a spinning skirt, lagging behind the material flow of the fabric. These qualitative features are captured with a minimal model of traveling waves on an inextensible, flexible, generalized-conical sheet rotating about a fixed axis. Conservation laws are used to reduce the dynamics to a quadrature describing a particle in a three-parameter family of potentials. One parameter is associated with the stress in the sheet, aNoether is the current associated with rotational invariance, and the third is a Rossby number which indicates the relative strength of Coriolis forces. Solutions are quantized by enforcing a topology appropriate to a skirt and a particular choice of dihedral symmetry. A perturbative analysis of nearly axisymmetric cones shows that Coriolis effects are essential in establishing skirt-like solutions. Fully non-linear solutions with three-fold symmetry are presented which bear a suggestive resemblance to the observed patterns.

     Fermer     

    New J. Phys., 15: 113055, 2013. Cf. aussi arXiv:1306.2619.

     


  •  

    Myotubularin and PtdIns3P remodel the sarcoplasmic reticulum in muscle in vivo

    Leonela Amoasii, Karim Hnia, Gaëtan Chicanne, Andreas Brech, Belinda Simone Cowling, Martin Michael Müller, Yannick Schwab, Pascale Koebel, Arnaud Ferry, Bernard Payrastre, Jocelyn Laporte

    Résumé     

    J. Cell Sci., 126(8): 1806, 2013.

     


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    Dipoles in thin sheets

    Jemal Guven, J. A. Hanna, Osman Kahraman, Martin Michael Müller

    Résumé     Plus d'infos

    Eur. Phys. J. E, 36: 106, 2013. Cf. aussi arXiv:1212.3262.

     


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    Fluid membrane vesicles in confinement

    Osman Kahraman, Norbert Stoop, Martin Michael Müller

    Résumé     Plus d'infos

    New J. Phys., 14: 095021, 2012.

     


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    Petal shapes of sympetaleous flowers: the interplay between growth, geometry and elasticity

    Martine Ben Amar, Martin Michael Müller, Miguel Trejo

    The growth of a thin elastic sheet imposes constraints on its geometry such as its Gaussian curvature KG. In this paper, we construct the shapes of sympetalous bell-shaped flowers with a constant Gaussian curvature. Minimizing the bending energies of both the petal and the veins, we are able to predict quantitatively the global shape of these flowers. We discuss two toy problems where the Gaussian curvature is either negative or positive. In the former case the axisymmetric pseudosphere turns out to mimic the correct shape before edge curling; in the latter case, singularities of the mathematical surface coincide with strong veins. Using a variational minimization of the elastic energy, we find that the optimal number for the veins is either four, five or six, a number which is deceptively close to the statistics on real flowers in nature.

     Fermer     Plus d'infos

    New J. Phys., 14: 085014, 2012. Choisi pour les Highlights of 2012.

     


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    Morphogenesis of membrane invaginations in spherical confinement

    Osman Kahraman, Norbert Stoop, Martin Michael Müller

    Résumé     Plus d'infos

    Europhys. Lett., 97(6): 68008, 2012. Cf. aussi arXiv:1201.2518.

     


  •  

    Conical instabilities on paper

    Jemal Guven, Martin Michael Müller, Pablo Vázquez-Montejo

    Résumé     Plus d'infos

    J. Phys. A: Math. Theor., 45(1): 015203, 2012. Cf. aussi arXiv:1107.5008.

     


  •  

    Interface-mediated interactions: Entropic forces of curved membranes

    Pierre Gosselin, Hervé Mohrbach, Martin Michael Müller

    Particles embedded in a fluctuating interface experience forces and torques mediated by the deformations and by the thermal fluctuations of the medium. Considering a system of two cylinders bound to a fluid membrane we show that the entropic contribution enhances the curvature-mediated repulsion between the two cylinders. This is contrary to the usual attractive Casimir force in the absence of curvature-mediated interactions. For a large distance between the cylinders, we retrieve the renormalization of the surface tension of a flat membrane due to thermal fluctuations.

     Fermer     Plus d'infos

    Phys. Rev. E, 83(5): 051921, 2011. Cf. aussi arXiv:1011.1221.

     


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    Self-Contact and Instabilities in the Anisotropic Growth of Elastic Membranes

    Norbert Stoop, Falk K. Wittel, Martine Ben Amar, Martin Michael Müller, Hans J. Herrmann

    Résumé     Plus d'infos

    Phys. Rev. Lett., 105(6): 068101, 2010. Cf. aussi arXiv:1007.1871.

     


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    Cell Model Approach to Membrane Mediated Protein Interactions

    Martin Michael Müller, Markus Deserno

    Résumé     Plus d'infos

    Prog. Theor. Phys. Suppl., 184: pp. 351-363, 2010.

     


  •  

    Hamiltonian formulation of surfaces with constant Gaussian curvature

    Miguel Trejo, Martine Ben Amar, Martin Michael Müller

    Résumé     Plus d'infos

    J. Phys. A: Math. Theor., 42(42): 425204, 2009.

     


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    Local Membrane Mechanics of Pore-Spanning Bilayers

    Ingo Mey, Milena Stephan, Eva K. Schmitt, Martin Michael Müller, Martine Ben Amar, Claudia Steinem, Andreas Janshoff

    The mechanical behavior of lipid bilayers spanning the pores of highly ordered porous silicon substrates was studied by local indentation experiments as a function of surface functionalization, lipid composition, solvent content, indentation velocity, and pore radius. Solvent-containing nanoblack lipid membranes (nano-BLMs) as well as solvent-free pore-spanning bilayers were imaged by fluorescence and atomic force microscopy prior to force curve acquisition, which allows distinguishing between membrane-covered and uncovered pores. Force indentation curves on pore-spanning bilayers attached to functionalized hydrophobic porous silicon substrates reveal a predominately linear response that is mainly attributed to prestress in the membranes. This is in agreement with the observation that indentation leads to membrane lysis well below 5% area dilatation. However, membrane bending and lateral tension dominates over prestress and stretching if solvent-free supported membranes obtained from spreading giant liposomes on hydrophilic porous silicon are indented.

     Fermer     Plus d'infos

    J. Am. Chem. Soc., 131(20): pp. 7031-7039, 2009.

     


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    Elasticity Mapping of Pore-Suspending Native Cell Membranes

    Bärbel Lorenz, Ingo Mey, Siegfried Steltenkamp, Tamir Fine, Christina Rommel, Martin Michael Müller, Alexander Maiwald, Joachim Wegener, Claudia Steinem, Andreas Janshoff

    The mechanics of cellular membranes is governed by a non-equilibrium composite framework consisting of the semiflexible filamentous cytoskeleton and extracellular matrix proteins linked to the lipid bilayer. While elasticity information of plasma membranes has mainly been obtained from whole cell analysis, techniques that allow to address local mechanical properties of cell membranes are desirable to learn how their lipid and protein composition is reflected in the elastic behavior on local length scales. Here, we introduce an approach based on basolateral membranes of polar epithelial Madin-Darby canine kidney (MDCK) II cells, prepared on a highly ordered porous substrate that allows elastic mapping on a submicrometer length scale. A strong correlation between the density of actin filaments and the measured membrane elasticity is found. Spatially resolved indentation experiments carried out with atomic force and fluorescence microscope permit to relate the supramolecular structure to the elasticity of cellular membranes. It is shown that the elastic response of the pore-spanning cell membranes is governed by the local bending modules rather than the lateral tension.

     Fermer     Plus d'infos

    Small, 5(7): pp. 832-838, 2009.

     


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    Conical Defects in Growing Sheets

    Martin Michael Müller, Martine Ben Amar, Jemal Guven

    Résumé     Plus d'infos

    Phys. Rev. Lett., 101(15): 156104, 2008. Cf. aussi arXiv:0807.1814.

     


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    How paper folds: bending with local constraints

    Jemal Guven, Martin Michael Müller

    Résumé     Plus d'infos

    J. Phys. A: Math. Theor., 41(5): 055203, 2008. Cf. aussi arXiv:0712.0978.

     


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    Contact lines for fluid surface adhesion

    Markus Deserno, Martin Michael Müller, Jemal Guven

    Résumé     Plus d'infos

    Phys. Rev. E, 76(1): 011605, 2007. Cf. aussi cond-mat/0703019.
    Choisi pour le Virtual Journal of Biological Physics Research.

     


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    Balancing torques in membrane-mediated interactions: Exact results and numerical illustrations

    Martin Michael Müller, Markus Deserno, Jemal Guven

    Résumé     Plus d'infos

    Phys. Rev. E, 76(1): 011921, 2007. Cf. aussi cond-mat/0702340.
    Choisi pour le Virtual Journal of Biological Physics Research.

     


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    Aggregation and vesiculation of membrane proteins by curvature-mediated interactions

    Benedict J. Reynwar, Gregoria Illya, Vagelis A. Harmandaris, Martin Michael Müller, Kurt Kremer, Markus Deserno

    Résumé     Plus d'infos

    Nature 447(7143): pp. 461-464, 2007.

     


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    How to determine local elastic properties of lipid bilayer membranes from atomic-force-microscope measurements: A theoretical analysis

    Davood Norouzi, Martin Michael Müller, Markus Deserno

    Measurements with an atomic force microscope (AFM) offer a direct way to probe elastic properties of lipid bilayer membranes locally: provided the underlying stress-strain relation is known, material parameters such as surface tension or bending rigidity may be deduced. In a recent experiment a pore-spanning membrane was poked with an AFM tip, yielding a linear behavior of the force-indentation curves. A theoretical model for this case is presented here which describes these curves in the framework of Helfrich theory. The linear behavior of the measurements is reproduced if one neglects the influence of adhesion between tip and membrane. Including it via an adhesion balance changes the situation significantly: force-distance curves cease to be linear, hysteresis and nonzero detachment forces can show up. The characteristics of this rich scenario are discussed in detail in this article.

     Fermer     Plus d'infos

    Phys. Rev. E, 74(6): 061914, 2006. Cf. aussi cond-mat/0602662.
    Choisi pour le Virtual Journal of Biological Physics Research.

     


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    Mechanical Properties of Pore-Spanning Lipid Bilayers Probed by Atomic Force Microscopy

    Siegfried Steltenkamp, Martin Michael Müller, Markus Deserno, Christian Hennesthal, Claudia Steinem, Andreas Janshoff

    Résumé     Plus d'infos

    Biophys. J., 91(1): pp. 217-226, 2006.

     


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    Interface mediated interactions between particles -- a geometrical approach

    Martin Michael Müller, Markus Deserno, Jemal Guven

    Résumé     Plus d'infos

    Phys. Rev. E, 72(6): 061407, 2005. Cf. aussi cond-mat/0506019.
    Choisi pour le Virtual Journal of Biological Physics Research.

     


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    Geometry of surface-mediated interactions

    Martin Michael Müller, Markus Deserno, Jemal Guven

    Résumé     Plus d'infos

    Europhys. Lett., 69(3): pp. 482-488, 2005. Cf. aussi cond-mat/0409043.

     


 

 

2. Livres

 

  • New Trends in the Physics and Mechanics of Biological Systems
    Lecture Notes of the Les Houches Summer School, vol. 92 (Oxford University Press, 2011),
    éd. par Martine Ben Amar, Alain Goriely, Martin Michael Müller et Leticia Cugliandolo.

    Chapitre 9 :
    The physics of the cell membrane
    Martin Michael Müller et Martine Ben Amar.

 

 


 

 

3. Mémoires

  • Theoretical examinations of interface mediated interactions between colloidal particles, mémoire (2004).
  •  

  • Theoretical studies of fluid membrane mechanics, thèse de doctorat (2007).


  • Symmetry breaking in bioelasticity, thèse d'habilitation à diriger des recherches (2015).

 

 

 
     

 

     © Martin Michael Müller