The thermotropic phase behaviour and chain dynamics of the dimyristoylphosphatidylcholine/myristic acid (1:2, mol/mol) mixture at pH 4.0 have been studied with 31P-NMR and spin-label ESR. Broadline proton-dipolar decoupled 31P-NMR spectra show that the system undergoes a transition from a lamellar phase to a non-lamellar phase at 47 degrees C. The 31P-NMR spectrum collapses, from a lamellar pow...

We consider the phase behavior of a symmetric AB diblock, blended with corresponding A and B homopolymers, all of equal chain length. Evaluating the phase diagram in mean-field theory at all compositions of the ternary blend, we find no hexagonal and cubic phases. However, up to three distinct lamellar phases can coexist, one being symmetric and the other two being asymmetric. For strong incomp...

The dilute lamellar phase of the nonionic surfactant C 12EO 5 was doped with goethite (iron oxide) nanorods up to a fraction of 5 vol %. The interaction between the inclusions and the host phase was studied by polarized optical microscopy (with or without an applied magnetic field) and by small-angle X-ray scattering. We find that, when the orientation of the nanorods is modified using the magn...

The characteristic 13-nm lamellar phase that is formed by lipids in the outermost layer of the skin, the stratum corneum (SC), is very important for the barrier function of the skin. To gain more insight into the molecular organization of this lamellar phase, we performed small-angle x-ray diffraction (SAXD) using various lipid mixtures mimicking the lipid composition in SC. In the SAXD pattern...

Phase behavior of distearoylphosphatidylethanolamine dispersed in excess glycerol has been examined by differential scanning calorimetry. Transformation from lamellar-gel to lamellar crystalline phase was found to take place at temperatures near 74.9 degrees C upon cooling and near 76.3 degrees C during heating scans. The transition can also be observed under isothermal conditions at temperatur...

The polymorphic phase behavior of 1-palmitoyl-2-lyso-sn-glycero-3-phosphocholine dispersions in excess water has been studied as a function of temperature and poly(ethylene glycol) (PEG) concentration, using proton dipolar-decoupled 31P NMR spectroscopy and turbidity measurements. The phase behavior was found to depend on both lipid concentration and PEG concentration, and most of the NMR exper...

We propose a model for the liquid-liquid (L(alpha)-->L(alpha(') )) phase transition observed in osmotic pressure measurements of certain charged lamellae-forming amphiphiles. The model free energy combines mean-field electrostatic and phenomenological nonelectrostatic interactions, while the number of dissociated counterions is treated as a variable degree of freedom that is determined self-con...

We consider the relative stability of parallel and perpendicular lamellar layers on corrugated surfaces. The model can be applied to smectic phases of liquid crystals, to lamellar phases of shortchain amphiphiles and to lamellar phases of long-chain block copolymers. The corrugated surface is modelled by having a single q-mode lateral corrugation of a certain height. The lamellae deform close t...

A phenomenological modelling approach has been developed to describe the massive transformation and the formation of lamellar microstructures during cooling in binary g titanium aluminides. The modelling approach is based on a combination of nucleation and growth laws which take into account the specific mechanisms of each phase transformation. Nucleation of massive and lamellar g is described ...

Quantitative nuclear magnetic resonance was used to measure the freezing behaviour of lamellar phases of phosphatidylcholine in water and in solutions of sorbitol. Both solute and solvent were deuterated in different series of experiments to allow the calculation of the partitioning of solute and solvent molecules between the lamellar phase and unfrozen bulk solution. Sorbitol, as well as water...