A5040029910- Liquid Crystal Research Advancements
- Erythrocyte Function and Pathophysiology
- Blood properties and coagulation
- Surfactants and Colloidal Systems
- Lipid Membrane Structure and Behavior
- Material Dynamics and Properties
- DNA and Nucleic Acid Chemistry
- Bacteriophages and microbial interactions
- Nanopore and Nanochannel Transport Studies
- Fluid Dynamics and Thin Films
- Digital Imaging for Blood Diseases
- Electrostatics and Colloid Interactions
- Digital Holography and Microscopy
- Rheology and Fluid Dynamics Studies
- Fluid Dynamics and Heat Transfer
- Granular flow and fluidized beds
- Microfluidic and Bio-sensing Technologies
- Vibration and Dynamic Analysis
- Mass Spectrometry Techniques and Applications
- Advanced Physical and Chemical Molecular Interactions
- Nanotechnology research and applications
- Molecular Communication and Nanonetworks
- Underwater Vehicles and Communication Systems
- Advanced Materials and Mechanics
- Field-Flow Fractionation Techniques
California Polytechnic State University
2016-2021
Brown University
2014
University of Colorado Boulder
2010-2011
University of California, Davis
2010
University of California, Los Angeles
2008-2009
The human red blood cell (RBC) membrane, a fluid lipid bilayer tethered to an elastic 2D spectrin network, provides the principal control of cell’s morphology and mechanics. These properties, in turn, influence ability RBCs transport oxygen circulation. Current mechanical measurements rely on external loads. Here we apply noncontact optical interferometric technique quantify thermal fluctuations RBC membranes with 3 nm accuracy over broad range spatial temporal frequencies. Combining this...
The membranes of human red blood cells (RBCs) are a composite fluid lipid bilayer and triangular network semiflexible filaments (spectrin). We perform cellular microrheology using the dynamic membrane fluctuations RBCs to extract elastic moduli this membrane. By applying known osmotic stresses, we measure changes in constants under imposed strain thereby determine nonlinear properties find that nonlinearities shear modulus tensed RBC can be well understood terms simple wormlike chain model....
Many soft-matter and biophysical systems are composed of monomers that reversibly assemble into rod-like aggregates. The aggregates can then order liquid-crystal phases if the density is high enough, ordering promotes increased growth Systems display coupled aggregation include wormlike micelles, chromonic liquid crystals, DNA RNA, protein polymers fibrils. Coarse-grained molecular models capture key features common to many different lacking; in particular, roles monomer aspect ratio...
We study experimentally and theoretically the hydrodynamic interaction of pairs circular inclusions in two-dimensional, fluid smectic membranes suspended air. By analyzing their Brownian motion, we find that radial mutual mobilities identical are independent size but angular coupling becomes strongly dependent when radius exceeds a characteristic length. These observations described well for arbitrary inclusion separations by model generalizes Levine-MacKintosh theory point-force response...
Hydrodynamic interactions play an important role in biological processes cellular membranes, a large separation of length scales often allowing such membranes to be treated as continuous, two-dimensional (2D) fluids. We study experimentally and theoretically the hydrodynamic interaction pairs inclusions two-dimensional, fluid smectic liquid crystal films suspended air. Such are ideal systems for performing controlled experiments they mechanically stable, highly uniform structure, have...
We study the microrheology of nanoparticle shells [A. D. Dinsmore et al., Science 298, 1006 (2002)] and viral capsids [I. L. Ivanovska Proc. Natl. Acad. Sci. U.S.A. 101, 7600 (2004)] by computing mechanical response function thermal fluctuation spectrum a viscoelastic spherical shell that is permeable to surrounding solvent. determine analytically damped dynamics bend compression modes coupled solvent both inside outside sphere in zero Reynolds number limit. identify fundamental length time...
We discuss the effects of external stress on thermal denaturation homogeneous DNA. Pulling double-stranded DNA at each end exerts a profound effect denaturation, or melting, long segment this molecule. transition stretching force applied to opposite ends DNA, including full consideration consequences excluded volume, analysis which is greatly simplified in case. find that three dimensions heat capacity acquires logarithmic dependence reduced temperature.
Thin fluid membranes embedded in a bulk of different viscosity are fundamental interest as experimental realizations quasi-two-dimensional fluids and models biological membranes. We have probed the hydrodynamics thin by active microrheology using small tracer particles to observe highly anisotropic flow fields generated around rigid oscillating post inserted into freely suspended smectic liquid crystal film that is surrounded air. In general, at distances more than few Saffman lengths from...
We have measured the temperature driven denaturing, or melting transition in poly d(A)-poly d(T) DNA oligomers of various lengths different buffer conditions. Our findings are clear disagreement with two state, reaction kinetics model, and we find that so-called zipper where denaturing proceeds through opening duplex at ends describes well dependence average number open base pairs. Analysis length parameters however suggest bubble formation is important transition, thermodynamic limit,...
Many soft-matter and biophysical systems are composed of monomers which reversibly assemble into rod-like aggregates. The aggregates can then order liquid-crystal phases if the density is high enough, ordering promotes increased growth Systems that display coupled aggregation include wormlike micelles, chromonic liquid crystals, DNA RNA, protein polymers fibrils. Coarse-grained molecular models capture key features common to many different lacking; in particular, role monomer aspect ratio...