4 research outputs found
A continuous isotropic-nematic liquid crystalline transition of F-actin solutions
The phase transition from the isotropic (I) to nematic (N) liquid crystalline
suspension of F-actin of average length m or above was studied by local
measurements of optical birefringence and protein concentration. Both
parameters were detected to be continuous in the transition region, suggesting
that the I-N transition is higher than 1st order. This finding is consistent
with a recent theory by Lammert, Rokhsar & Toner (PRL, 1993, 70:1650),
predicting that the I-N transition may become continuous due to suppression of
disclinations. Indeed, few line defects occur in the aligned phase of F-actin.
Individual filaments in solutions of a few mg/ml F-actin undergo fast
translational diffusion along the filament axis, whereas both lateral and
rotational diffusions are suppressed.Comment: 4 pages with 4 figures. Submitted to Physical Review Letter
Kinetic pathways of the Nematic-Isotropic phase transition as studied by confocal microscopy on rod-like viruses
We investigate the kinetics of phase separation for a mixture of rodlike
viruses (fd) and polymer (dextran), which effectively constitutes a system of
attractive rods. This dispersion is quenched from a flow-induced fully nematic
state into the region where the nematic and the isotropic phase coexist. We
show experimental evidence that the kinetic pathway depends on the overall
concentration. When the quench is made at high concentrations, the system is
meta-stable and we observe typical nucleation-and-growth. For quenches at low
concentration the system is unstable and the system undergoes a spinodal
decomposition. At intermediate concentrations we see the transition between
both demixing processes, where we locate the spinodal point.Comment: 11 pages, 6 figures, accepted in J. Phys.: Condens. Matter as
symposium paper for the 6th Liquid Matter Conference in Utrech