Month: October 2019

The Department of Chemical and Biomolecular Engineering welcomes Dr. Abhyudai Singh, an Associate Professor in the Departments of Electrical and Computer Engineering, Biomedical Engineering, Mathematical Sciences, and Center for Bioinformatics and Computational Biology.     Dr. Singh’s seminar titled, “Systems Biology in Single Cells:  A Tale of Two Viruses”  will be held in 100 Earle Hall on October 10th from 2:00 to 3:00 pm.

In the noisy cellular environment, expression of genes has been shown to be stochastic across organisms ranging from prokaryotic to human cells. Stochastic expression manifests as cell-to-cell variability in the levels of RNAs/proteins, in spite of the fact that cells are genetically identical and are exposed to the same environment. Development of computationally tractable frameworks for modeling stochastic fluctuations in gene product levels is essential to understand how noise at the cellular level affects biological function and phenotype. I will introduce state-of-the-art computational tools for stochastic modeling, analysis and inferences of biomolecular circuits. Mathematical methods will be combined with experiments to study infection dynamics of two viral systems in single cells.  First, I will show how stochastic expression of proteins results in intercellular lysis time and viral burst size variations in the bacterial virus, lambda phage. Next, I will describe our efforts in stochastic analysis of the Human Immunodeficiency Virus (HIV) genetic circuitry. Our results show that HIV encodes a noisy promoter and stochastic expression of key viral regulatory proteins can drive HIV into latency, a drug-resistant state of the virus.

Abhyudai Singh earned his bachelor’s degree in mechanical engineering from the Indian Institute of Technology in Kanpur, India. He received master’s degrees in both mechanical and electrical & computer engineering from Michigan State University, and a master’s degree in ecology, evolution and marine biology from University of California Santa Barbara (UCSB). After earning his doctoral degree in electrical & computer engineering in 2008, also from UCSB, he completed postdoctoral work in UC San Diego’s Department of Chemistry and Biochemistry. From 2011 to 2017 he was an Assistant Professor in the Departments of Electrical & Computer Engineering, Biomedical Engineering and Mathematical Sciences  at the University of Delaware, and was promoted to Associate Professor in 2017. The research interests of Abhyudai Singh are in dynamics, control, and identification of biomedical systems with applications to systems/synthetic biology and neuroscience.

The Department of Chemical and Biomolecular Engineering welcomes Dr. Connie B. Roth, an Associate Professor in the Department of Physics at Emory University.     Dr. Roth’s seminar titled, “Local Property Changes Near Interfaces in Nanostructured Polymer Blends and Films” will be held in 100 Earle Hall on October 3rd from 2:00 to 3:00 pm.

Nanostructured morphologies with extensive interfaces have become the hallmark of high performance multicomponent materials.  Understanding how local material properties change near interfaces is clearly crucial to designing an optimized morphology to create the correct global macroscopic characteristics desired from an amalgam of these local effects.  Contrary to the traditional textbook paradigm, our group has recently demonstrated that local dynamical properties across polymer domains can become strongly coupled upon welding of two dissimilar polymer interfaces creating broad gradients in local material properties.  Using a localized fluorescence technique, we have investigated how the local glass transition temperature T_g(z) changes across interfaces between two polymers with widely different bulk glass transition temperatures T_g^bulk.  Starting with a single interface between two semi-infinite domains (ΔT_g^bulk ≈ 80 K), we show that broad profiles in local T_g(z) across dissimilar polymer-polymer interfaces are established, spanning hundreds of nanometers and observed to be asymmetric relative to the composition profile.  A key finding of these results is the observation that the broad coupling of dynamics across the dissimilar polymer-polymer interface only occurs if this interface is welded together by annealing to equilibrium.  Efforts to understand what factors during polymer interface formation cause these broad profiles in local T_g(z) find that chain connectivity appears to be surprisingly important.  This is confirmed by measurements near silica substrates with tethered chains where low grafting densities (~10 vol% tethered chains) are observed to cause large +50 K increases in local T_g.  We now explore what property changes take place in multilayer systems during interface annealing using different experimental techniques with the goal of understanding how interfaces mediate dynamical coupling across dissimilar polymer domains.

Connie B. Roth, an Associate Professor of Physics at Emory University, received her Ph.D. and M.Sc. in Physics from the University of Guelph, Canada.  Following postdoctoral positions at Simon Frazier University, Vancouver, and Northwestern University, Chicago, Dr. Roth joined Emory’s faculty in 2007.  Prof. Roth has received a NSF CAREER Award, ACS PRF Doctoral New Investigator grant, was the 2009 recipient of the Division of Polymer Physics (DPOLY) UKPPG Polymer Lecture Exchange from the American Physical Society (APS), and most recently received the 2019 Fellow Award from the North American Thermal Analysis Society.  She is serving as the DPOLY Program Chair for the 2020 APS meeting.