Chemical Engineering Seminar
Roseanna N. Zia is an Assistant Professor of Chemical Engineering at Stanford University. She received her Ph.D. from the California Institute of Technology in Mechanical Engineering in 2011 with Professor John F. Brady, for development of theory in colloidal hydrodynamics and microrheology. Zia subsequently conducted post-doctoral study of colloidal gels at Princeton University, in collaboration with Professor William B. Russel. Zia began her faculty career at Cornell in January 2013, then subsequently moved her research group to Stanford University in 2017. Dr. Zia’s research includes developing micro-continuum theory for structure-property relationships of flowing suspensions, elucidating the mechanistic origins of the colloidal glass transition, and microscopic modeling of reversibly bonded colloidal gels, which resulted in discovery that gel aging is actually ongoing but very slow phase separation and the finding that mechanical yield of colloidal gels is actually a non-equilibrium phase transition, triggered by changes in osmotic pressure. More recently she is developing models of biological cells, examining biological processes orchestrated by colloidal-scale forces. Dr. Zia’s work has been recognized by several awards, including the NSF BRIGE Award, the NSF CAREER Award, the Publication Award from the Society of Rheology, the Office of Naval Research (ONR) Young Investigator award, the ONR Director of Research Early Career Award, the Engineering Sonny Yau (’72) Teaching Award, and the PECASE Award. In addition, Zia serves as an Associate Editor for the Journal of Rheology, on the Advisory Boards of the journal Physics of Fluids and AIChE Journal.
The frontier in operational mastery of biological cells arguably resides at the interface between biology and colloid physics: cellular processes that operate over colloidal length scales, where continuum fluid mechanics and Brownian motion underlie whole-cell scale behavior. It is at this scale that much of cell machinery operates and is where reconstitution and manipulation of cells is most challenging. This operational regime is centered between the two well-studied limits of structural and systems biology: the former focuses on atomistic-scale spatial resolution with little time evolution, and the latter on kinetic models that abstract space away. Colloidal hydrodynamics modeling bridges this divide by unifying the disparate length and time-scales of solvent-molecule and colloidal dynamics, and may hold a key to numerous open questions in biological cell function. I will discuss our physics-based computational model of a biological cell, where biomolecules and their interactions are physically represented, individually and explicitly. With it, we study a model process: translation elongation. We find that Brownian self-diffusion alone is insufficient to recover experimentally measured elongation rates but accounting for other colloidal forces improves agreement.