Cooper Saturated Hydrocarbons

The relation of the constitution of saturated petroleum fractions to their insecticidal efficiency was shown in the case of a single insect species in a previous paper (9). To extend this study the Citrus Experiment Station of the University of California, the Shell Oil Co., and the New York State Agricultural Experiment Station cooperated to include other species and to examine the insecticidal properties of various hydrocarbon compositions derived directly or indirectly from petroleum as well as synthetic hydrocarbons of known constitution. Part of the program planned for the New York Station consisted of ... 

The influence of cholesterol concentration at various temperatures on the thermotropic phase behavior and organization of saturated PE bilayers has been studied by combining DSC, FT-IR, and 31P-NMR. It was found that incorporation of low levels of cholesterol into the bilayer caused a progressive reduction in the temperature, enthalpy, and overall cooperativity of the lipid hydrocarbon chain melting transition... 

The phosphatidylcholines (I) and the phosphatidylglycerols (n) represent typical phospholipid structures, with a polar phosphodiester "headgroup" attached via a diacylglycerol unit to two long hydrocarbon "tails." At low temperatures, the tails of saturated phospholipids with identical acyl chains adopt a conformation in which all (or very nearly all) of the C-C bonds are trans. As the temperature is raised, one observes a phase transition resulting from a cooperative disordering of the hydrocarbon tails — a process which requires 8-10 kcal/mole for two Cig chains. " This order-disorder transition is studied most simply and directly by high-sensitivity DSC. 

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