Interactions of glass with the living world: impact of nanoheterogeneity
Himanshu Jain, PhD
Friday, September 25, 2020
Fluidity, jamming and glassy behavior in biological tissues
Dapeng Bi, PhD
Friday, October 16, 2020
Cells must move through tissues in many important biological processes, including embryonic development, cancer metastasis, and wound healing. Often these tissues are dense and a cell's motion is strongly constrained by its neighbors, leading to glassy dynamics. Although there is a density-driven glass transition in particle-based models for active matter, these cannot explain liquid-to-solid transitions in confluent tissues, where there are no gaps between cells and the packing fraction remains fixed and equal to unity. I will demonstrate the existence of a new type of rigidity transition that occurs in confluent tissue monolayers at constant density. The onset of rigidity is governed by a model parameter that encodes single-cell properties such as cell-cell adhesion and cortical tension. I will also introduce a new model that simultaneously captures polarized cell motility and multicellular interactions in a confluent tissue and identify a glassy transition line that originates at the critical point of the rigidity transition. This work suggests an experimentally accessible structural order parameter that specifies the entire transition surface separating fluid tissues and solid tissues. Finally, I will discuss recent work using a culture of human lung epithelial tissue to compare a newly discovered mode of fluidization of jammed cells ñ the unjamming transition (UJT) ñ with the canonical epithelial-to-mesenchymal transition (EMT).
Drop Generation in Electro-Coflows
Josefa Guerrero-Millan, PhD
Friday, October 30, 2020
Controlled generation of micron and sub-micron sized drops continues to be of strong interest for the scientific community due to the variety of applications in many different fields. Microfluidics allows the precision manipulation of small volume of fluids and it is used in areas like microanalysis, point-of-care detection and diagnostics, in vitro disease and tissue modeling, and organic synthesis, among others. In our experiments, we use glass-based microfluidics, where 3D flows travel in coaxially aligned glass capillaries producing emulsion drops. In addition to the hydrodynamic stresses, we use electrical stresses to force the drop formation. The presence of charge in the interface of the liquids adds another control parameter in the drop production process. In this talk, we present a qualitative study of jet structure and droplet formation in the different electrohydrodynamic spraying regimes when the hosting media is a flowing dielectric liquid.
Seminar series organizers: Dr. Trinanjan Datta (email@example.com), Dr. Shaobin Miao (firstname.lastname@example.org), Dr. José A. Jiménez (email@example.com), Dr. Abdul Malmi-Kakkada (firstname.lastname@example.org).
Seminar series sponsored by: Augusta University Research Institute, College of Science and Mathematics, Department of Chemistry and Physics