Outros  

• Aula Inaugural Do Programa De Engenharia Mecânica (COPPE- UFRJ)


• 19 de março de 2012, Centro de Tecnologia, Bloco G, sala 122
  Fonte: Prof. Fernando Duda (UFRJ)

  DNA in Flow

  Prof. Eric S.G. Shaqfeh
  Departments of Chemical and Mechanical Engineering
  Stanford University, Stanford CA 94305

  Within the last 20 years, the use of microscopy to visualize DNA chains in flow as pioneered by Chu and co-workers has revolutionized our understanding the fluid flows of long chain hydrocarbons or “polymers”. These flows are critical to the processing of plastics for molded parts, coatings, and even food. Rather than simply postulating models for polymers in various “strong” flow fields (i.e. those that create significant molecular deformation), researchers can now directly examine the conformational statistics of a molecule in flow far from equilibrium. Combining these experimental studies with computational molecular models, researchers have an extremely powerful tool to probe the physics in the molecular dynamics.

  In this presentation, I will review the state of research in single DNA dynamics studies in flow including a variety of important flow fields and I will discuss outstanding questions that have developed in this research. I will also introduce and discuss a few relatively new applications of single molecule microscopy involving DNA dynamics in micro-post arrays, as scaffolds for molecular wires and in non-dilute solution. All of these examples indicate that the applications of examining polymer dynamics “one molecule at a time” are burgeoning and will play an important role in the study of polymeric liquids in the foreseeable future.

  LOCAL: Centro de Tecnologia, Bloco G, sala 122 
  DATA: 19/03/2012 
  HORÁRIO: 14:00h 
  Maiores informações: Fernando Duda (duda@mecanica.ufrj.br)

  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).

  Eric has been married to Terhilda Garrido for 28 years, and they have two children, Stefan, 23 and Elena, 18.

  
   

   

• Seminário em Engenharia Mecânica ARTHUR PALMEIRA RIPPER NETO- (COPPE-UFRJ)


• 21 de março de 2012, Centro de Tecnologia, Bloco G, sala 122
  Fonte: Prof. Fernando Duda (UFRJ)

  Platelet Margination in the Microcirculation

  Prof. Eric S.G. Shaqfeh
  Departments of Chemical and Mechanical Engineering
  Stanford University, Stanford CA 94305

  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 at least 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.

  LOCAL: Centro de Tecnologia, Bloco G, sala 122 
  DATA: 21/03/2012 
  HORÁRIO: 10:00h 
  Maiores informações: Fernando Duda (duda@mecanica.ufrj.br)

  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).

  Eric has been married to Terhilda Garrido for 28 years, and they have two children, Stefan, 23 and Elena, 18.

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