Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session R16: Glassy Dynamics: From Simple Models to Biological Tissues IILive
|
Hide Abstracts |
Sponsoring Units: GSNP DSOFT Chair: Patrick Charbonneau, Duke University |
Thursday, March 18, 2021 8:00AM - 8:12AM Live |
R16.00001: Impact of adhesion on the shape and rearrangements of biomimetic emulsions in static and dynamical packings Lorraine Montel, Iaroslava Golovkova, Elie Wandersman, Alexis Michel Prevost, Thibault Bertrand, Léa-Laetitia Pontani During morphogenesis, cells differentiate and reorganize to acquire their shape and function. In addition to biological cues, the mechanical properties of cells and their interactions are essential to this process. Yet, in biological systems, it is challenging to isolate the role of one parameter. We developed adhesive emulsions as a simpler and more controlled model system to study the role of adhesion in tissue mechanics. We can thus extract the sole contribution of adhesion to the organization of soft particles assemblies. |
Thursday, March 18, 2021 8:12AM - 8:24AM Live |
R16.00002: Assessing the connection between cellular rearrangements and local structure using information in models of biological tissues. Indrajit Tah, Tristan Sharp, Andrea Liu, Daniel Sussman The global dynamics of cells in dense confluent epithelial tissues are linked strongly to global structural properties. During embryonic development, cancer invasion and wound healing, such tissues can undergo a transition from a solid-like jammed state to a fluid-like unjammed state that is predicted by an average of cell shape. We push this further to use structural information to predict the mobility of individual cells, identifying a linear combination of local structural features, "softness," that is strongly predictive of cell rearrangements. We use an information-theoretic measure to quantify the extent to which softness determines impending topological rearrangements and combine it with isoconfigurational ensemble results to show that softness captures nearly all of the information about rearrangements that is obtainable from structure. This information is large in the solid phase of the model and decreases rapidly as state variables are varied into the fluid phase. |
Thursday, March 18, 2021 8:24AM - 8:36AM Live |
R16.00003: Local rotational dynamics reveals strain dependence in amorphous particle packings Dong Wang, Nima Nejadsadeghi, Anil Misra, Yan Li, Shashi Shekhar, Joshua Dijksman Glassy dynamics in amorphous packings is commonly probed by quantifying various nonaffine displacement metrics such as D2min, χ4, Okubo-Weiss etc. While the rigidity-inducing proliferation of steric hindrance makes such metrics interesting, it also makes these metrics difficult to interpret. Particle rotations are much less sensitive to steric hindrance and other confinement effects. We study the dynamics of rotations in sheared amorphous quasi-two-dimensional disk packings at various friction coefficients and packing densities. We demonstrate that even for round particles, particle rotations display the hallmarks of glassy dynamics. Studying rotations offers a few advantages: the diffusive nature of rotational dynamics evidences imminent shear jamming already after a few percent transient strain, in the absence of any measurable pressure. Additionally, the spatially varying rotation dynamics is correlated and can be quantified with a well-studied spatial autocorrelation measure called Moran’s I. Such analysis show the emergence of clusters of anticorrelated motion. Our work suggests that particle rotation dynamics is an essential field to consider in the understanding of amorphous material mechanics. |
Thursday, March 18, 2021 8:36AM - 8:48AM Live |
R16.00004: Direct experimental evidence for the Gardner transition in a colloidal glass Eric Schwen, Meera Ramaswamy, Danilo Liarte, Itai Cohen A major breakthrough in relating glass formation and jamming has been the identification of the Gardner transition. This phase transition occurs as glassy systems are compressed toward a jammed state and corresponds to a marginal phase where single energy basins split into a complex hierarchy of metastable subbasins. While the Gardner transition has been confirmed analytically for mean-field systems in infinite dimensions, evidence from simulations and experiments in three dimensions is limited. Here, we present experiments aimed at directly observing the predicted metastable states of the Gardner phase in a colloidal glass. We use a compression cell mounted on a confocal microscope to repeatedly compress a binary colloidal glass and induce shifts between metastable states. By precisely locating and tracking particles, we identify particle subcages for different metastable states of the same glass. These results will concretely establish whether the Gardner transition can be seen in a three-dimensional glass and repeated experiments determine the volume fraction at which the Gardner transition takes place. Our experiments help to lay the groundwork for further investigations into the rich phenomenology of the metastable glass. |
Thursday, March 18, 2021 8:48AM - 9:00AM Live |
R16.00005: Glassy dynamics in the hard matrix model Jaron Kent-Dobias, Veit Elser We introduce the hard matrix model (HMM) which consists of an orthogonal matrix exploring an energy landscape proportional to its 1-norm. In its low-temperature phase it is confined to a harmonic well around a matrix whose entries all have the same magnitude. These ground states are proportional to Hadamard matrices, which are useful in statistics and coding theory but are combinatorially hard to enumerate or even produce. Any hopes that gradient descent on the HMM would find new Hadamards are dashed by the observed numerics: beginning at moderate size, the ground state is never found from a high-temperature quench and dynamic timescales grow superexponentially with inverse temperature. We describe our progress toward understanding these phenomena and speculate on the relevance of the HMM to structural glasses. |
Thursday, March 18, 2021 9:00AM - 9:12AM Live |
R16.00006: Non-Equilibrium Universal Features of Annealing and Aging in Granular Piles, Paula Gago, Stefan Boettcher We explore the compaction dynamics of a granular pile after a hard quench from a liquid into the glassy regime. First, we establish that the otherwise athermal granular pile during tapping exhibits annealing behavior comparable to glassy polymer or colloidal systems. The pile undergoes a glass transition and “freezes” into different non-equilibrium glassy states for different annealing speeds, starting from the same initial equilibrium state. Then, we quench the system instantaneously to below the glass transition regime to study the ensuing aging dynamics. In this classical aging protocol, the density increases (i.e., the potential energy of the pile decreases) logarithmically over several decades in time. Instead of system-wide, thermodynamic measures, we identify the intermittent, irreversible events (“quakes”) that actually drive the glassy relaxation process. We find that the event rate decelerates hyperbolically, which explains the observed increase in density when the integrated contribution to the downward displacements is evaluated. We argue that such a hyperbolically decelerating event rate is consistent with a log-Poisson process, also found as a universal feature of aging in many thermal glasses. (Accepted in PNAS, see https://arxiv.org/abs/2010.01991.) |
Thursday, March 18, 2021 9:12AM - 9:24AM Live |
R16.00007: The Distribution of Distances to Instabilities of Jammed Packings of Frictionless Spheres Under Load Horst-Holger Boltz, Ding Xu, Ning Xu, Andrea Liu We study an athermal, jammed packing of frictionless soft spheres to revisit the contribution of local (fold) instabilities to the vibrational density of states D(ω). For low frequencies, they result in a power-law behaviour D(ω)~ωα. We show that we can infer this exponent α from a careful inspection of incipient instabilities under shear and pressure load exploiting the fact that the underlying statistics has to take the form of an extreme value distribution. Taking into account shear- and compression-stable packings, we gather some physical insight into the meaning of α and its dependence on finite-size effects and preparation protocol. |
Thursday, March 18, 2021 9:24AM - 9:36AM Live |
R16.00008: Mechanism of Clogging in Microfluidic Devices Abigail Wilson, Sydney W Holway, Thomas Coons, Jeffrey S. Guasto, Tim Atherton
|
Thursday, March 18, 2021 9:36AM - 9:48AM Not Participating |
R16.00009: Direct Measurements of the Complexity of the Sphere Packing Energy Landscape Valerie Beale, Eric Corwin Granular systems have complex and high dimensional potential energy landscapes. By directly characterizing this landscape we can gain statistical insight into material properties. We approximate this landscape as that of frictionless spheres and characterize their energy landscape by enumerating the local minima found within randomly chosen small volumes. Inspired by the mark-recapture method often used in estimation of populations, we repeatedly minimize a family of slightly perturbed harmonic soft sphere packings to determine the density and sizes of the minima found within that volume. We report on the complexity and statistical properties of the energy landscape as a function of the distance from jamming and comment on the relation to the theorized Gardner transition in jamming. |
Thursday, March 18, 2021 9:48AM - 10:00AM Live |
R16.00010: Elasto-plasticity Mediates Avalanche Dynamics in Supercooled Liquids Below the Mode-Coupling Temperature Rahul N Chacko, François P Landes, Giulio Biroli, Olivier Dauchot, Andrea Liu, David Reichman Athermal glasses under quasi-static shear respond elastically to local yield events. The resulting strain field can trigger additional rearrangements, resulting in an avalanche of yield events, as encapsulated in elasto-plastic models [1]. Similar avalanche dynamics have been observed in simulations of deeply supercooled liquids. In this talk, we show that this scenario of elastically-triggered avalanches applies to the dynamics of a model two-dimensional supercooled liquid below the mode-coupling temperature. As the temperature is increased past the mode-coupling temperature, this elastic signature vanishes, suggesting a transition to a different avalanche dynamics at higher temperatures. |
Thursday, March 18, 2021 10:00AM - 10:12AM Live |
R16.00011: Dionysian Hard Sphere Packings are Mechanically Stable at Vanishingly Low Densities Robert Dennis, Eric Corwin High strength-to-weight ratio materials can be constructed by either maximizing strength or minimizing weight. Tensegrity structures and aerogels take very different paths to achieving high strength-to-weight ratios but both rely on internal tensile forces. In the absence of tensile forces, removing material eventually destabilizes a structure. Nevertheless, we construct hard sphere packings that have asymptotically zero density and yet maintain finite strength, thus achieving an unbounded strength-to-weight ratio. These constructions, which we call Dionysian, have positive bulk and shear moduli and are linearly resistant to every applied deformation, both internal and external. By demonstrating that there is no lower bound on the density of stable structures, this work allows for the construction of arbitrarily lightweight high-strength materials. |
Thursday, March 18, 2021 10:12AM - 10:24AM On Demand |
R16.00012: Monte Carlo Suite for the Atomistic Simulation of Polymer-Based Interfacial and Nanocomposite Systems Miguel Herranz, Pablo Ramos, Daniel Martinez Fernandez, Javier Benito, Nikos Karayiannis, Manuel Laso We present a Monte Carlo (MC) protocol for the atomistic simulation of polymer-based systems. It is built around chain-connectivity-altering moves [1], cluster detection/displacement algorithms [2] and identity-exchange transitions. We demonstrate its efficiency by applying it on diverse systems varying from athermal linear chains under extreme, tube- or plate-like confinement, polymer nanocomposites with spherical and cylindrical fillers of varied concentration and size, and blends of polymeric and monomeric substances. Confinement can be realized through the presence of flat orthogonal, cylindrical or spherical surfaces [3]. The proposed MC suite has general applicability and can readily incorporate different potentials for non-bonded pair-wise interactions and chain stiffness in simulations of multi-body, 2-D or 3-D systems. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700