P. T. C. So | Searcharxiv

arXiv1993

Pressure Induced Hydration Dynamics of Membranes

Pressure-jump initiated time-resolved x-ray diffraction studies of dynamics of the hydration of the hexagonal phase in biological membranes show that (i) the relaxation of the unit cell spacing is non-exponential in time; (ii) the Bragg peaks shift smoothly to their final positions without significant broadening or loss in crystalline order. This suggests that the hydration is not diffusion limited but occurs via a rather homogeneous swelling of the whole lattice, described by power law kinetics with an exponent $ β= 1.3 \pm 0.2$.

cond-mat↗

arXiv1992

Pressure Induced Topological Phase Transitions in Membranes

Some highly unusual features of a lipid-water liquid crystal are revealed by high pressure x-ray diffraction, light scattering and dilatometric studies of the lamellar (bilayer $L_α$) to nonlamellar inverse hexagonal ($H_{II}$) phase transition. (i) The size of the unit cell of the $H_{II}$ phase increases with increasing pressure. (ii) The transition volume, $ΔV_{bh}$, decreases and appears to vanish as the pressure is increased. (iii) The intensity of scattered light increases as $ΔV_{bh}$ decreases. Data are presented which suggest that this increase is due to the formation of an intermediate cubic phase, as predicted by recent theoretical suggestions of the underlying universal phase sequence.

cond-mat↗