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Complex Fluids 2007
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Modeling Liquid Crystal Materials and
Processes in Biological Systems
CSIC Building (#406),
Seminar Room 4122.
Directions: home.cscamm.umd.edu/directions
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Modeling Liquid Crystal Materials and Processes in
Biological Systems
Professor
Alejandro Rey
McGill University
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Abstract:
Liquid crystal phases are found in DNA, proteins,
lipids and polysaccharides. Frozen-in, chiral liquid
crystal ordering also occurs in solid biocomposites
such as insect cuticle, muscle, plant cell walls and
collagen, where the helicoid structure is believed
to arise by self-assembly processes. Spinning of
silk fibers by spiders is another biological polymer
process that relies on liquid crystal self-assembly.
I will discuss the progress and challenges of
modeling in three such applications: (1) Biological
helicoids form by directed self-assembly. Theory and
computer simulation of chiral phase ordering show
that the directed self-assembly process reproduces
the natural structures. The computational results
shed light on the role of chiral ordering on the
formation of helicoidal monodomains. (2) Spinning of
spider silk involves a complex sequence of phase
transitions that includes nematic phase ordering in
the duct section of the spinning apparatus.
Simulation of phase ordering under capillary
confinement replicates the observed structures found
in Nephila clavipes and other orb-weavers. The
computational results shed light on the role of
defect textures in the fiber spinning process. (3)
Biological membranes are smectic liquid crystals
that display fexoelectricity, or coupling between
electric fields and curvature. Models based on
smectic elasticity and polarization thermodynamics
are used to derive the electroelastic shape
equation, whose solution gives the membrane shape
under external fields. The theoretical results shed
light on the various ways electric fields affect
membrane shape and functioning.
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