<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div class="" style="font-family: HelveticaNeue;"><span class="">Dear Soft Matter Colleagues and Friends,</span></div><div class="" style="font-family: HelveticaNeue;"><span class=""><br class=""></span></div><div class=""><div class="" style="font-family: HelveticaNeue;">On Friday 24 March 2023 at 9:30 AM at the UW Faculty of Physics (Pasteura 5, Warsaw; room 1.40) we are hosting a seminar during which</div><div class="" style="font-family: HelveticaNeue; margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;"><font face="HelveticaNeue" class=""><br class=""></font></div><div class="" style="font-family: HelveticaNeue; margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue" class=""><b class="">Michał Bogdan </b>(IChF PAN)</font></div><div class="" style="font-family: HelveticaNeue; margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;"><font face="HelveticaNeue" class=""><br class=""></font></div><div class="" style="font-family: HelveticaNeue; margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue" class="">will give a talk</font></div><div class="" style="font-family: HelveticaNeue; margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;"><font face="HelveticaNeue" class=""><br class=""></font></div><div class="" style="font-family: HelveticaNeue; margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue" class=""><b class=""><span class="" style="font-family: "Helvetica Neue";">Crystallization and topology-induced dynamical heterogeneities in soft granular clusters</span><span class="Apple-tab-span" style="white-space: pre;"> </span></b></font></div><div class="" style="font-family: HelveticaNeue; margin: 0px; font-stretch: normal; line-height: normal;"><b class=""><br class=""></b></div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><span class=""><font face="HelveticaNeue" class=""><b class="">Authors: </b>Michał Bogdan, Mihir Durve, Leon Jurkiewicz, Sauro Succi, Jan Guzowski</font></span></div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><span class=""><font face="HelveticaNeue" class=""><b class=""><br class=""></b></font></span></div><div class="" style="font-family: HelveticaNeue; margin: 0px; font-stretch: normal; line-height: normal;"><b class="">Abstract</b></div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><div class="" style="margin: 0cm; background-color: white;"><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><span class="Apple-tab-span" style="font-family: "Helvetica Neue"; white-space: pre;"> </span>Soft-granular media such as dense emulsions, foams or tissues tend to exhibit either fluid- or solid-like properties depending on the applied stresses. However, the internal dynamics of soft granular systems bound by closed interfaces is poorly understood, while it remains of significant interest in diverse fields ranging from material science (porous materials) and tissue engineering (granular bioinks) to developmental biology (embryos, organoids) and medicine (circulating tumor cell clusters). Here, we report the spontaneous occurrence of crystalline-like hexagonal structures within soft granular clusters which self-organize under external flow. We use a densely packed double emulsion as a model soft granular material to produce clusters of sizes of 20-40 grains (droplets). We find that, optimally, the crystallites emerge under weak flows, when the internal shear stresses slightly agitate the system allowing internal rearrangements. Excessive flows destroy the delicate crystalline structure and lead to constant internal recirculations, i.e., effective fluidization of the granular medium. Upon subjecting the clusters to cycles of constriction and relaxation/expansion, we also find differences between the behaviours of two groups of droplets: those within the inner part of the cluster and those at its rim, with the latter subjected to larger deformations and less frequent rearrangements, effectively acting as an elastic solid-like membrane around the inner fluid-like core. This structural-dynamical heterogeneity appears to be of purely topological origin and as such we expect it to remain universal in various types of soft granular clusters or jets including also cell aggregates, organoids or bioprinted tissues.</div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><br class=""></div></div></div><div class="" style="font-family: HelveticaNeue; margin: 0px; font-stretch: normal; line-height: normal;">We warmly welcome everyone to attend the talk and the Soft Matter Coffee Break after the seminar, held in room 2.63 (2nd floor).</div></div><div class="" style="font-family: HelveticaNeue;"><br class=""></div><div class="" style="font-family: HelveticaNeue;"><div dir="auto" class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div class=""><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue" class="">Maria Ekiel-Jeżewska</font></div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue" class="">Maciej Lisicki</font></div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue" class="">Piotr Szymczak</font></div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue" class="">Panagiotis Theodorakis</font></div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue" class="">Marek Trippenbach</font></div></div></div></div><div class="">
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