摘要：

X-Ray diffraction studies have been carried out on some lipids of various chemical compositions: two monoglycerides (glyceryl-monodecanoate and glyceryl-monododecanoate), several phospholipids (synthetic di-palmitoyllecithin, egg lecithin, lysolecithin derived from the latter, egg phosphatidylethanolamine) and sphingolipids (sphingomyelin and cerebrosides isolated from beef brain) have been studied. The structure of these lipid-water systems depends on concentration and temperature: crystalline phases are formed at low temperatures, whereas higher temperatures and high lipid content promote the formation of liquid-crystalline phases. At low lipid content and high temperature, only lysolecithin forms a micellar solution in water; for the other lipids, a suspension of a liquid-crystalline phase in excess water is observed. Four liquid-crystalline phases, already described in other soap or lipid systems, have been observed here. 1. (a) A lamellar phase occurs in the following systems: water-monoglyceride (monodecanoate: 25 °C; monododecanoate: 45 °C); water-sphingomyelin (45 °C); water-cerebrosides (72 °C); water-phosphatidylethanolamine (20 °C); water-egg lecithin (5 to 35 °C) and anhydrous lecithin at high temperature. 2. (b) A hexagonal phase, made of a regular array of lipid cylinders, is observed in the water-lysolecithin system at 35 °C. 3. (c) An inverted hexagonal phase (cylinders made of water) occurs in the water-phosphatidylethanolamine system at 55 °C. 4. (d) A cubic phase is observed in anhydrous lecithin at high temperature. The structural parameters of these phases and the polymorphism of the various lipids are discussed.

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