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Dynamique et rhéologie des fluides complexes (gels, polymères, mousses, colloïdes)
(36) Production(s) de l'année 2019
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A localization transition underlies the mode-coupling crossover of glasses
Auteur(s): Coslovich D., Ninarello A. S., Berthier L.
(Article) Publié:
Scipost Physics, vol. p.77 (2019)
Texte intégral en Openaccess :
Ref HAL: hal-02445176_v1
Ref Arxiv: 1811.03171
DOI: 10.21468/SciPostPhys.7.6.077
WoS: 000505803200006
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
4 Citations
Résumé: We study the equilibrium statistical properties of the potential energy landscape of several glass models in a temperature regime so far inaccessible to computer simulations. We show that unstable modes of the stationary points undergo a localization transition in real space close to the mode-coupling crossover temperature determined from the dynamics. The concentration of localized unstable modes found at low temperature is a non-universal, finite dimensional feature not captured by mean-field glass theory. Our analysis reconciles, and considerably expands, previous conflicting numerical results and provides a characteristic temperature for glassy dynamics that unambiguously locates the mode-coupling crossover.
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Uncovering the dynamic precursors to motor-driven contraction of active gels
Auteur(s): Alvarado Jose, Cipelletti L., Koenderink Gijsje H.
(Article) Publié:
Soft Matter, vol. 15 p.8552-8565 (2019)
Texte intégral en Openaccess :
Ref HAL: hal-02374362_v1
Ref Arxiv: 1812.06484
DOI: 10.1039/c9sm01172b
WoS: WOS:000493519700010
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
1 Citation
Résumé: Cells and tissues have the remarkable ability to actively generate the forces required to change theirshape. This active mechanical behavior is largely mediated by the actin cytoskeleton, a crosslinkednetwork of actin filaments that is contracted by myosin motors. Experiments and active gel theorieshave established that the length scale over which gel contraction occurs is governed by a balancebetween molecular motor activity and crosslink density. By contrast, the dynamics that govern thecontractile activity of the cytoskeleton remain poorly understood. Here we investigate the microscopicdynamics of reconstituted actin–myosin networks using simultaneous real-space video microscopy andFourier-space dynamic light scattering. Light scattering reveals different regimes of microscopicdynamics as a function of sample age. We uncover two dynamical precursors that precede macroscopicgel contraction. One is characterized by a progressive acceleration of stress-induced rearrangements,while the other consists of sudden, heterogeneous rearrangements. Intriguingly, our findings suggest aqualitative analogy between self-driven rupture and collapse of active gels and the delayed rupture ofpassive gels observed in earlier studies of colloidal gels under external loads.
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Nature of excitations and defects in structural glasses
Auteur(s): Scalliet C., Berthier L., Zamponi Francesco
(Article) Publié:
Nature Communications, vol. 10 p. (2019)
Texte intégral en Openaccess :
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Front-Mediated Melting of Isotropic Ultrastable Glasses
Auteur(s): Flenner Elijah, Berthier L., Charbonneau Patrick, Fullerton C.
(Article) Publié:
Physical Review Letters, vol. 123 p.175501 (2019)
Texte intégral en Openaccess :
Ref HAL: hal-02358763_v1
Ref Arxiv: 1903.09108
DOI: 10.1103/PhysRevLett.123.175501
WoS: WOS:000491998300008
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
1 Citation
Résumé: Ultrastable vapor-deposited glasses display uncommon material properties. Most remarkably, upon heating they are believed to melt via a liquid front that originates at the free surface and propagates over a mesoscopic crossover length, before crossing over to bulk melting. We combine swap Monte Carlo with molecular dynamics simulations to prepare and melt isotropic amorphous films of unprecedendtly high kinetic stability. We are able to directly observe both bulk and front melting, and the crossover between them. We measure the front velocity over a broad range of conditions, and a crossover length scale that grows to nearly $400$ particle diameters in the regime accessible to simulations. Our results disentangle the relative roles of kinetic stability and vapor deposition in the physical properties of stable glasses.
Commentaires: 7 pages, 6 figures; accepted for publication in Phys. Rev. Lett. Réf Journal: Phys. Rev. Lett. 123, 175501 (2019)
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Does the Adam-Gibbs relation hold in simulated supercooled liquids?
Auteur(s): Ozawa M., Scalliet C., Ninarello A. S., Berthier L.
(Article) Publié:
The Journal Of Chemical Physics, vol. 151 p.084504 (2019)
Texte intégral en Openaccess :
Ref HAL: hal-02302300_v1
Ref Arxiv: 1905.08179
DOI: 10.1063/1.5113477
WoS: WOS:000483889300020
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
9 Citations
Résumé: We perform stringent tests of thermodynamic theories of the glass transition over the experimentally relevant temperature regime for several simulated glass-formers. The swap Monte Carlo algorithm is used to estimate the configurational entropy and static point-to-set lengthscale, and careful extrapolations are used for the relaxation times. We first quantify the relation between configurational entropy and the point-to-set lengthscale in two and three dimensions. We then show that the Adam-Gibbs relation is generally violated in simulated models for the experimentally relevant time window. Collecting experimental data for several supercooled molecular liquids, we show that the same trends are observed experimentally. Deviations from the Adam-Gibbs relation remain compatible with random first order transition theory, and may account for the reported discrepancies between Kauzmann and Vogel-Fulcher-Tammann temperatures. Alternatively, they may also indicate that even near $T_g$ thermodynamics is not the only driving force for slow dynamics.
Commentaires: 13 pages, 8 figures. Réf Journal: J. Chem. Phys. 151, 084504 (2019)
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Population dynamics in a structured habitat
Auteur(s): Pitard E., Munoz François
(Article) Publié:
Les Dossiers D'agropolis International, vol. 23 p.38-38 (2019)
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