Platelet Margination in the Microcirculation
Prof. Eric S.G. Shaqfeh
Departments of Chemical and Mechanical Engineering
Stanford University, Stanford CA 94305
Local: Centro de Tecnologia, Bloco G, sala 122
Data: 21/03/2012
Hora: 10h
Maiores informações: Fernando Duda (This email address is being protected from spambots. You need JavaScript enabled to view it.)
Abstract: It is well known that individual vesicles or liposomes (i.e. fluid enclosed by a lipid bilayer membrane suspended in a second fluid) are characterized by a remarkable dynamics in flow. For vesicles that are “near spheres” this dynamics includes at least 5 different types of orbits in shear flow that are functions of the viscosity ratio between the inner and outer fluid as well as the Capillary number based on the bending modulus. However, this dynamics becomes even more rich as the reduced volume falls below about 0.65 where now there are atleast three equilibrium shapes (prolates, discocytes, and stomatocytes) which are linearly stable. It is therefore not surprising that a suspension of vesicles is characterized by fascinating collective behavior as well. I will discuss our recent development of a numerical code (based on Loop subdivision) which allows the Stokes flow simulation of non-dilute suspensions of vesicles and capsules at essentially any value of the reduced volume. We will then use these numerical simulations to examine a very important naturally occurring consequence of the interactions in these suspensions -- hemostasis in the small vessels. Hemostasis relies on naturally occurring blood particles such as platelets being concentrated near the vessel walls. The adhesion of platelets to an injured vessel site is a critical initial stage for the formation of a platelet plug to stop bleeding. Any reduction of hematocrit and/or flow rate can both slow down the margination of platelets toward the vessel wall and in turn hamper the formation of the platelet plug. The resulting coagulopathy can be life-threatening, so understanding this process, which we shall demonstrated is an inherently fluctuation-induced hydrodynamic process, is critical to developing therapies for the mitigation of these coagulopathies.
Biographical information: Eric Shaqfeh is the Lester Levi Carter Professor and Department Chair of Chemical Engineering at Stanford University. He joined Stanford’s faculty in 1990 after earning a B.S.E. summa cum laude from Princeton University (1981), and a M.S. (1982) and Ph.D. (1986) from Stanford University. In 2001 he received a dual appointment and became Professor of Mechanical Engineering. He is most recently (as of 2004) a faculty member in the Institute of Computational and Mathematical Engineering at Stanford.
Shaqfeh’s current research interests include non-Newtonian fluid mechanics (especially in the area of elastic instabilities, and turbulent drag reduction), nonequilibrium polymer statistical dynamics (focusing on single molecules studies of DNA), and suspension mechanics (particularly of fiber suspensions and particles/vesicles in microfluidics). He has authored or co-authored over 170 publications and has been an Associate Editor of the Physics of Fluids since 2006.
Shaqfeh has received the APS Francois N. Frenkiel Award 1989, the NSF Presidential Young Investigator Award 1990, the David and Lucile Packard Fellowship in Science and Engineering 1991, the Camile and Henry Dreyfus Teacher--Scholar Award 1994, the W.M. Keck Foundation Engineering Teaching Excellence Award 1994, the 1998 ASEE Curtis W. McGraw Award, and the 2011 Bingham Medal from the Society of Rheology. A Fellow of the American Physical Society, he has held a number of professional lectureships, most recently the Merck Distinguished Lectureship, Rutgers (2003), the Corrsin Lectureship, Johns Hopkins (2003) and the Katz Lectureship, CCNY (2004). He was also the Hougen Professor of Chemical Engineering at the University of Wisconsin (2004) and the Probstein Lecturer at MIT (2011).
