We have synthesized a homologous series of saturated 1,2-di-O-n-acyl-3-O-( -D-galactopyranosyl)-sn-glycerols with oddand even-numbered hydrocarbon chains ranging in length from 10 to 20 carbon atoms, and have investigated their physical properties using differential scanning calorimetry (DSC), X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy. The DSC results show a com...

Interfaces between lamellar and disordered phases, and grain boundaries within lamellar phases, are investigated employing a simple Landau free energy functional. The former are examined using analytic, approximate methods in the weak segregation limit, leading to density profiles which can extend over many wavelengths of the lamellar phase. The latter are studied numerically and exactly. We fi...

Ceramides were isolated from the pig stratum corneum (SC) and mixed in varying molar ratios with either cholesterol or with cholesterol and free fatty acids. The phase behavior of the mixtures was studied by small-(SAXD) and wide-angle (WAXD) X-ray diffraction. Ceramides alone did not exhibit a long range ordering. Upon addition of cholesterol to ceramides, lamellar phases were formed and a hex...

An entropically stabilized cetylpyridinium chloride, hexanol, and heavy brine lyotropic lamellar phase subjected to shear flow has been observed here by small angle neutron scattering to undergo collapse of smectic order above a threshold shear rate. The results are compared with theories predicting that such a lamellar phase sheared above a critical rate should lose its stability by a loss of ...

– We study the relaxation modes of an interface between a lyotropic lamellar phase and a gas or a simple liquid. The relaxation is found to be qualitatively different from those of both simple liquids and single-component smectic-A liquid crystals. It is governed by a non-inertial, diffusive mode whose decay rate increases quadratically with wavenumber, |ω| = Aq. The coefficient A depends on th...

We measure diffusion coefficients in the lamellar phase of the nonionic binary system C(12)EO(6)/H(2)O using fluorescence recovery after photobleaching. The diffusion coefficient across the lamellae shows an abrupt increase upon approaching the lamellar-isotropic phase transition. We interpret this feature in terms of defects connecting the surfactant structure. An estimation of the defect dens...

The phase behavior of bovine brain sphingomyelin in water has been determined by polarizing light microscopy, differential scanning calorimetry, and X-ray diffraction. Lamellar phases, in which water is intercalated between sheets of lipid molecules arranged in the classical bilayer fashion, are present over much of the phase diagram. An order-disorder transition separates the high temperature,...