Triolein film

Another example, similar to that of the oleic acid oxidation, is provided by the study (Mittelmann and Palmer, 36) of the rate of oxidation of triolein films. Their results will be considered in more detail below, where their mathematical analysis will be discussed. 

Figure 1.1 A standard lipid-containing SPMD with three molecular welds near each end. Note the low interfacial tension causes intimate contact (i.e., the presence of a lipid film on the membrane interior surface) between the triolein and the membrane even where air bubbles exist. Reprinted with permission from the American Petroleum Institute (Huckins et al., 2002a).

A thin film of oil-like material was visible after 28 d on the exterior surfaces of the SPMD membrane. Analysis of this film indicated that the triolein impurities, oleic acid and methyl oleate, were the major constituents. This external lipid film (Petty et al., 1993) appeared to contain imbibed particulates. Although the film was removed from the SPMDs by solvent rinsing and analyzed separately, some lipid-mediated desorption of particle-associated PCBs and subsequent diffusion into the SPMD may have occurred prior to solvent-removal of the film. This observation suggests the potential for SPMD concentrations to reflect both vapor phase concentrations and to a lesser extent, lipid-extracted particulate-associated residues (see Section 3.9.2.). Unfortunately, concentrations of more chlorinated congeners in particulates collected on GFFs from the NIOSH method were often below quantitation limits, because only a small volume of air was sampled (1 m ) using this active method. 

Experiments on similar lines were carried out by Devaux Ann. Meport Smithsonian Inst, 1913, p. 261), Marcelin (J. de Physique, I. 19,1914) and Labrouste Ann. de Phys. xiv. 164,1920). Meanwhile advances in other branches of molecular physics had led to very much more certain values for molecular dimensions, and for triolein. Devaux estimated the thickness of the thinnest film at 10 A. The... 

The table shows that many molecules are far from being symmetrical in shape, a direct confirmation of his theory. We notice incidentally the need for care in calculating the number of molecular layers contained in a thin film by the method of Rayleigh and Devaux, without further consideration. (If for example Devaux had chosen cerotic acid instead of triolein as his test case, he would have found 31 A. as the thickness of the film, whereas the cube root of the volume of a molecule is 31x25 = 9 2 A. Thus, neglecting the shape of the molecule, cerotic acid would have appeared to form a trimolecular layer.)... 

Eight binary systems are reported. Six include cholesterol as one component of the mixed film. The second components in these six films were myristic acid, methyl palmitate, ethyl palmitate, 1,2-dimyristin, 1,2-dimyristoyl-3-lecithin, and l,2-didecanoyl-3-lecithin. In addition, the systems trilaurin-dimyristoyl lecithin and triolein-dimyristoyl lecithin... 

The first recorded observation (Adam, 13) of reaction in a monolayer, made in 1926, describes the oxidation by acid permanganate of a film of oleic acid. The reaction proceeds with expansion of the film, since the double bond in the middle of the chain is converted into a dihydroxy group, which is sufficiently hydrophilic to pull the hydrocarbon chain flat on to the surface of the water. Triolein and erucic and brassidic acids all behave in the same way. Adam also observed (14) that films of 7-hydroxy-stearolac.tone, spread on alkali, hydrolyzed to 7-hydroxystearic acid. 

None of the venoms, however, showed any interaction with films of cholesterol or protein, nor did hydrolysis occur in films of tripalmitin, triolein, cerebron, or sphingomyelin. The reaction with lecithin is highly specific. Not only is it sensitive to the chemical structure of the film, but the reaction rate may also be greatly altered by slight changes in the orientation of the molecules in the film or by changes in the pH of the solution or of the concentration of venom. 

To investigate these, Mittelmann and Palmer (36) made a mathematical study of the oxidation of films of triolein by permanganate. Just... 

For the system of Figure 9.9 interfacial tension as measured by the spinning drop technique fell during the first few minutes of the experiment to 0.05 mN/m, remained there for about half an hour, then increased over a period of 2 h to 0.2 to 0.3 mN/m, not far below the value of 0.4 mN/m obtained at long times for pure triolein with the same surfactant solution. This behavior indicates that the surfactant film at the interface between the drop and surfactant solution shifted from lipophilic to hydrophilic conditions as oleic acid was solubilized, the minimum in tension occurring at the balanced condition (see Figure 9.3). Support for this interpretation was obtained by repeating... 

The interpretation of small SANS data from systems of type D20/NaCl- -decane/triolein-CioE4 showed that the order of the microstructure systematically decreases with increasing triolein content (Fig. 11.8(c) and Table 11.3). However, the value of the amphiphilicity factor [49, 50] /a = —0.65 indicates that the pure triolein microemulsion is still a microemulsion in the narrower sense. The bending constants k and i< obtained from phase diagrams and scattering curves furthermore verify that the rigidity of the amphiphilic film decreases with increasing triolein content (Fig. 11.9). 

Figure 11.9 Bar bending modulus k (a) and bar saddle-splay modulus i< (b) for the systems H20(D20)/NaCI as well as H20/NaCI-n-decane/triolein-CioE4 as a function of 3. With increasing p the bending modulus of the amphiphilic film k decreases, while the saddle-splay modulus i< becomes less negative.

Steareth-16 Steareth-25 Stearyl alcohol Sucrose laurate Sulfated castor oil Tallamide DEA TEA-oleate TEA-stearate Triolein PEG-6 esters surfactant, photo chemicals Sodium myristyl sulfate surfactant, photographic film Cocamidopropyl hydroxysultaine N,N-Dimethyl-N-lauric acid-amidopropyl-N-(3-sulfopropyl)-ammonium betaine N,N-Dimethyl-N-myristyl-N-(3-sulfopropyl)-ammonium betaine N,N-Dimethyl-N-palmityl-N-(3-sulfopropyl)-ammonium betaine N,N-Dimethyl-N-stearyl-N-(3-sulfopropyl)-ammonium betaine... 

Self-excited oscillations have been reported to occur in L-B films of dioleyl lecithin (Y-fihns and Z-films). The films separated equimolar solutions of KCl and NaCl solutions, and also in polytetrafluoroethylene membrane doped with triolein and monolein [3, 4], No satisfactory theory has been proposed so far to explain self-excited oscillations in such systems. However, it has been postulated that such a situation can occur on account of any one of the following factors [5]... 

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