Showing papers by "Joke A. Bouwstra published in 1992"
TL;DR: In this paper, wide-angle X-ray diffraction measurements were performed as a function of temperature and hydration on human stratum corneum, and the results confirmed results obtained with small-angle diffraction (Bouwstra et al., J. Invest. Dermatol., 97 (1991b) 1005-1012).
258 citations
TL;DR: In this article, the effect of a series of alkyl-azones (N-alkylazocycloheptane-2-one) on the structure of human stratum corneum has been studied by small angle X-ray scattering.
42 citations
01 Aug 1992
TL;DR: In this paper, a three-phase region L1 + L2 + D was found for the DDAB/dodecane/water system with respect to phase behavior and emulsion stability.
Abstract: The DDAB/dodecane/water system has been studied with respect to phase behavior and emulsion stability, and the effects from added electrolytes have been investigated. The repeat distance in the lamellar liquid crystalline phase has been measured by X-ray scattering. Electron microscopy pictures of the lamellar phase reveal that thermodynamically unstable vesicles are formed in the pure phase, introducing a reduction in repeat distance. At low salinity and surfactant concentrations, a three-phase region L1 + L2 + D is found. Emulsions prepared in this three-phase region are extremely stable against coalescence. Upon addition of electrolytes, this three-phase equilibrium disappears and is replaced by a new three-phase region L1 + L2 + F and a reduction in emulsion stability is obtained. This reduction has been discussed with respect to several factors, including the change in curvature obtained for the surfactant film when electrolytes are added. At constant salinities, however, the existence of a hexagonal phase does not influence the stability of the emulsions.
10 citations
TL;DR: The morphology of the structures formed after hydration of lipid films of cholesteryl hemisuccinate/dipalmitoylphosphatidylcholine (CHEMS/DPPC) was investigated in low ionic strength solutions and confirmed the hypothesis by Hauser (Biochim.
8 citations
TL;DR: In this article, four synthetic surfactants, consisting of alkyi chains of either 16 or 18 carbon units, with a polar head of either three or seven ethylene oxide units were studied using thermal analysis in both hydrated and non-hydrated states.
7 citations
01 Jan 1992
TL;DR: In this paper, the formation of vesicles from single-chain surfactants, i.e. polyoxyethylene alkyl ethers, has been discussed, and it was shown that stable vesicle can only be obtained from those surfactant which from liquid state bilayers and which possess a relative small hydrophilic head group compared to the alkyal chain.
Abstract: In this paper the forming of vesicles from single chain surfactants, i.e. polyoxyethylene alkyl ethers, has been discussed. The alkyl chain of the surfactants varied between 10 and 18, while the number of oxyethylene units varied between 3 and 7. Stable vesicles could only be prepared from those surfactants which from liquid state bilayers and which possess relative small hydrophilic head group compared to the alkyl chain. No vesicles could be prepared from surfactants which form gel-state bilayers. However after addition of cholesterol it was possible to prepare vesicles from all the surfactants under study. This is probably due to a decrease in interfacial area per “surfactant/cholesterol” molecule and to an increase in the mobility of the alkyl chains present in bilayers in the gel-state. The former has been confirmed by phase diagram studies of the system H2O + C12EO6 (60% m/m)/cholesterol (40% m/m).
4 citations