those of S-OH. The transfer characteristics of the up stroke therefore are expected to be somewhat different. The results of the interfacial forces, the transfer properties observed for SA(Cd) monolayers, are shown in Figure 9. The pressure dependencies of the forces during both the up-and down-stroke processes were almost similar to those obtained for S-OH. It was also found that the transfer properties were well elucidated by the dynamic forces.The relationships between the dynamic interfacial forces and the transfer characteristics established in this study were obtained for almost all of the aliphatic molecules that could be transferred uniformly from aqueous subphase onto solid substrates. Therefore it can be concluded that the transfer mechanism of the LB films for both up-and down-stroke processes is rather qualitatively elucidated by the dynamic interfacial force. On the basis of the thermodynamic arguments described in this study, the process having the minimum energy variation prevails against other possible processes.In this study, we have carried out the experiments of the first-layer deposition onto the various hydrophobic substrates. Although the multilayer deposition is done using amphiphilic molecules having various polar and nonpolar groups, the transfer characteristics can be quantitatively analyzed by measuring the dynamic interfacial forces during the processes. ConclusionIn this paper, we investigated the mechanism of LB film transfer from the water surface onto the substrate, experimentally. By varying the surface pressure of the monolayer film ( x ) and the hydrophilic/hydrophobic property contact angle (8,) of the substrate, the transfer ratio ( p ) was measured. It was found that transfer ratio ( p ) changes discretely between 0 and 1 at a critical point of x and 8,. To analyze this transition characteristics of film transfer in more detail, the interfacial force Cr, applied to the substrate was observed during the deposition process. It was found that the value off was almost unchanged with varying a for the case where the film was not transferred onto the substrate. On the other hand, for the case where the film was entirely transferred onto the substrate, the value off linearly increases with x for the up-stroke process of hydrophilic substrate and linearly decreases with a for the down-stroke process of the hydrophobic substrate. These results were thermodynamically analyzed by taking into account the energy variation accompanied with a vertical displacement of the substrate. It is confirmed that the characteristics of LB film transfer are consistent with the thermodynamical principle that the process advances toward a direction of smaller energy variation.The partitioning of 1 -propanol, 2-propano1, 1 -butanol, 2-butanol,2-methyl-2-propanol, 1-butylurea, tert-butylurea, cyclohexanol, 6-caprolactam, 1-hexanol, 1-octanol, and 1-decanol between the micelles of dodecyl-(C12), tetradecyl-(C14), and hexadecyl-(C16) trimethylammonium bromides and the surrounding aqueous phase has been deter...
6445dehydration may be required to account for this. The present study, as shown above, provides us some evidence to indicate the structure of acid sites included in silica-alumina and silica-coated alumina. First, we can conclude that the silica on alumina does not possess such acid sites as found in the silica-alumina catalyst. In other words, silanol attached to AI does not show strong Bransted acidity. This is in agreement with the conclusion by Kawakami et al. on the basis of the quantumchemical cal~ulations.~ They proposed a distorted structure consisting of silicon and aluminum for the strong Bransted acid sites. In the boundary layer between alumina and silica, the species as assumed or the substituted aluminum cation like in zeolite framework could be formed to play the role of the Bransted acid site.Because the electronegativity of the silicon cation (Si4+) is larger than that of the aluminum cation (AI3+), the silicon atom pulls an electron to become negatively charged; in place of that, the hydrogen of hydroxide becomes positively charged, Le., -A I U Si--OH+. Because of the induced effect, silanol attached to aluminum may behave as a weak Bransted acid site. It can be postulated that the distribution of the acid strength is fine due to the discrete structure of deposit silanol. Therefore, the silica monolayer on alumina could catalyze the appropriate reaction effectively. The sharp distribution of the acid site with a homogeneous strength of the acidity may be a characteristic of the material distinguishable from usual mixed oxides. ConclusionsI . Chemical vapor deposition of silicon methoxide on alumina formed the monolayer of silica fully covering the alumina surface. Further deposition of silica is possible; double-layer formation is suspected.2. The silica monolayer does not possess the strong Bransted acidity for the cumene cracking but does possess the weak acidity to catalyze the isomerization of butene and the dehydration of tert-butyl alcohol. The acidity may be created by an induced effect of the assumed species -A I U S i -O H , and a fine distribution of the acidity strength is estimated.The effects of I-propanol, 1-butanol, I-hexanol, and 1 -octanol on the micellization parameters of sodium lauryl sulfate (NaLS) in heavy water (D20) and in aqueous urea solutions, solvent systems with stronger and weaker hydrogen-bonded skeletal structures, respectively, than in ordinary water, have been determined at 25 OC. We have also determined the transfer free energy of an alcohol from H20 to D20 and also to urea solutions by head space gas chromatography. Results show the following: (1) The ability to depress the critical micelle concentration (cmc) increases in going from D20 to H20 to 5 M urea, the direction of decreasing structuredness of the solvent system. (2) The coaggregation equation ( J . Phys. Chem. 1983, 87, 5443), relating the ability to depress the cmc and the ability to increase the micellar degree of ionization to the distribution coefficient of the amphiphilic additive between the m...
use of the ability of a nonionic amphiphile to depress the levorotation of a protein at 546 nm as a measure of the ability to strengthen hydrophobic interaction (HI) in the protein solution, the effect of homologous 1-alkanols (ethanol, propanol, butanol, hexanol, octanol, decanol, dodecanol, tridecanol, tetradecanol, pentadecanol, and hexadecanol) on the optical rotation of /Mactoglobulin (/SLG) has been determined at 25 °C. For the anesthetically active alcohols, we have investigated the effect at concentrations that do not exceed the concentration necessary to anesthetize 50% of subjects (EDgo) and verified the previous conclusion that anesthetic potency is linearly related to the ability to strengthen HI in the protein solution. The ability to strengthen HI depends on the protein concentration and the alcohol chain length. HI increases with decreasing protein concentration. The effect of chain length shows two distinctive regions, the first region from C2 to C12 showing an initial linear increase up to C8 with the ability thereafter tending to level off at dodecanol. In the second region, the ability to strengthen HI increases linearly from C13 to C18. The onset of curvature in the ability to strengthen HI after C8 suggests the size of hydrophobic region to be about C8. HI in the second region is interpreted as probably due to intramolecular bridging of two hydrophobic regions on the surface of the protein. The corresponding strengthening of HI by 1-alkanols in solutions of sodium dodecyl sulfate (SDS) was also determined. The ability to strengthen HI as a function of chain length shows no discontinuity or significant curvature. It is argued that the hydrophobic interaction of anesthetic agents with membrane proteins, forming ionic or hydrophilic channels, is represented by the interaction observed in the first region (C2-C12) in /3LG, thus rationalizing the "cutoff" effect in anesthetic potency in homologous 1-alkanols.
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