ELFT HÍRADÓ

[Szeminárium koordinátor <sem-admin AT szfki.hu>]

SZFI SeminarRobin SelingerKent State University (vendéglátó: Salamon 
Péter)Frank-Read sources in nematic liquid crystals: engineered mechanism for 
heterogeneous defect nucleationThursday, 7 July 2022, 10:00, Bldg 1, 
auditorium,  
https://wigner-hu.zoom.us/j/87329092467?pwd=NlRKWUQ4cks2K3Ara3c5V3BCOC9EUT09  
 Meeting ID: 873 2909 2467  Passcode: 174961The Frank-Read (F-R) source, a 
well-studied concept in metallurgy, is a mechanism by which dislocation loops 
are emitted via repeated heterogeneous nucleation, giving rise to ductility 
in crystalline solids. We demonstrate that the same fundamental mechanism 
enables multiplication of disclination loops in nematic liquid crystals under 
shear. And while F-R sources form randomly in deformed crystals e.g. through 
dislocation pinning by impurities, by contrast we can precisely engineer F-R 
sources in a nematic liquid crystal cell by inscribing anchoring patterns on 
the confining substrates. We discuss possible applications in passive and 
active nematics.  SZFI SeminarJonathan SelingerKent State 
University (vendéglátó: Salamon Péter)Geometry and Mechanics of Disclinations 
in Nematic Liquid CrystalsThursday, 7 July 2022, 10:30, Bldg 1, auditorium,  
https://wigner-hu.zoom.us/j/87329092467?pwd=NlRKWUQ4cks2K3Ara3c5V3BCOC9EUT09  
 Meeting ID: 873 2909 2467  Passcode: 174961In this talk, we present recent 
progress in understanding topological defects in liquid crystals, both 
conventional and active. We emphasize that topology is only one part of the 
theory of topological defects. Beyond topology, we need geometry to 
characterize the orientational properties of defects. We need energy and 
forces to understand the interactions between defects, and the conventional 
and active stimuli acting on them. Further, we need dynamics to understand 
the motion of defects under these forces, in the presence of dissipation. We 
discuss all of these aspects of the theory of defects in both two and three 
dimensions. Minden érdeklődőt szívesen látunk! - Everyone is welcome to 
attend.Róbert Juhászsem-admin AT szfki.hu