Bulletin of the American Physical Society
63rd Annual Meeting of the APS Division of Fluid Dynamics
Volume 55, Number 16
Sunday–Tuesday, November 21–23, 2010; Long Beach, California
Session LL: Mini-Symposium on Microhydrodynamics of Lipid Bi-layer Membranes |
Hide Abstracts |
Chair: Petia Vlahovska, Brown University Room: Long Beach Convention Center 202A |
Monday, November 22, 2010 3:35PM - 4:01PM |
LL.00001: Dynamic Coarse-grained Modeling of Lipid Bilayer Membranes Invited Speaker: A coarse-grained approach capturing features at the level of of individual lipid molecules is presented for the study of dynamic phenomena related to bilayer membranes. The model takes into account molecular interactions between lipids, hydrodynamic coupling, and thermal fluctuations. The model is parameterized to have bending elasticity, compression moduli, and shear viscosity comparable to experimentally studied bilayer membranes. To carry-out simulation studies using the model, new stochastic computational methods are introduced based on fluctuating hydrodynamics. Using this approach, specific simulation results are presented which characterize how molecular level interactions contribute to bilayer mechanics (stiffness, tension, compressibility), bilayer rheology (shear viscosity, normal stress differences), and the mobility of bilayer embedded particles (single and pair diffusivity tensors). Applications of the bilayer model and computational methods to problems in cell biology are also discussed. [Preview Abstract] |
Monday, November 22, 2010 4:01PM - 4:27PM |
LL.00002: Composition dynamics in lipid bilayer membranes over long length and time scales Invited Speaker: We present a stochastic phase-field model for multicomponent lipid bilayers, which explicitly accounts for the quasi-two-dimensional hydrodynamic environment unique to a thin fluid membrane immersed in aqueous solution. Dynamics over a wide range of length scales (from nanometers to microns) for durations up to seconds and longer are readily accessed and provide a direct comparison to fluorescence microscopy measurements in ternary lipid/cholesterol mixtures. Simulations of phase separation kinetics agree with experiment and elucidate the role of hydrodynamics in the coarsening process. [Preview Abstract] |
Monday, November 22, 2010 4:27PM - 4:53PM |
LL.00003: Single vesicle dynamics in various flows: Experiment versus theory Invited Speaker: Dynamics of a single vesicle in shear, elongation, and general flows is investigated experimentally. Phase diagram of three vesicle dynamical states is obtained experimentally in both shear and general flows. The new control parameter, the ratio of the vorticity to the strain rate $\omega/s$, allows following an experimental path, which scans across the whole phase diagram with a single vesicle. Surprisingly, all three states and transitions between them are obtained on the same vesicle and at the same viscosity of inner and outer fluids. We reveal the physical nature of the key dynamical state, coined by us trembling, which shows up in intrinsic shape instability on each cycle resulted in periodical bursting of higher order harmonics depending on the value of the control parameter proportional to $\omega/s$. The dynamics of trembling state is compared with dynamics of a vesicle a time-dependent elongation flow, where the wrinkling instability was discovered, and similar features are identified. Quantitative comparison with recently proposed models and numerical simulations for vesicle dynamics is reviewed. [Preview Abstract] |
Monday, November 22, 2010 4:53PM - 5:19PM |
LL.00004: Vesicles in a shear and Poiseuille flows Invited Speaker: Vesicles, capsules and Red Blood Cells (RBCs) under flow are subject to considerable attention from theoretical, numerical and experimental point of views. Understanding their motions and dynamics is essential both at the fundamental level as a branch of biocomplex fluids, and at the technological level, such as the lab-on-chip technologies, targeted drug delivery, and blood flow diseases. First, we describe the dynamics of individual biomimetic (vesicles and capsules) and biological entities (RBCs) under a simple shear flow, and overview the current state of the knowledge. Comparison with available experiments will be provided. We then discuss the non-trivial rheology of dilute vesicle suspensions and results from experiments involving oscillatory shear with non-zero mean shear rate. Finally, we address a longstanding puzzle in the blood microcirculatory research: why do red blood cells adopt a non-symmetrical shape (called slipper shape) even in a symmetric flow? Our work shows that the symmetric shape is unstable in flow conditions encountered in microvasculature. Moreover, by adopting a slipper shape, the RBC acquires higher flow efficiency than the symmetric (parachute) shape. The extension of this study to a collection of cells will be outlined. [Preview Abstract] |
Monday, November 22, 2010 5:19PM - 5:45PM |
LL.00005: Deformation and stability of lipid membranes in electric fields Invited Speaker: The challenges and recent advances in the theoretical modeling of lipid membrane dynamics in electric fields will be overviewed. Vesicle shapes and the stability and poration of lipid bilayers will be discussed in relation to the complex electromechanics of membranes: First, the lipid membrane is an insulating shell impermeable to ions. Second, it is essentially a two-dimensional incompressible-fluid sheet; under stress lipid membranes store elastic energy in bending, while membranes made of cross-linked polymers are more likely to be stretched and sheared. Third, lipid membranes are extremely soft and they are easily bent by the thermal noise. I will show how the dynamical coupling of interface charging, membrane deformation, lipid density redistribution, and fluid motion gives rise to rich and sometimes surprising behavior of lipid membranes in electric fields. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700