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The apparent molar volume and the apparent molar adiabatic compressibility of the sugar-based surfactants methyl 6- O-octanoyl-α- d-glucopyranoside (α-MOnG), methyl 6- O-octanoyl-β- d-glucopyranoside (β-MOnG), and octyl β- d-glucoside were measured over a wide concentration range. Also, the aggregation number of their micelles was determined from the Debye plot using static light scattering data. It was found that the micellar aggregation number for α-MOnG is 179 at 35 °C, which is 1.5 times larger than that for β-MOnG, suggesting that the anomerism of the head group influences the packing of the monomers during micelle formation. [ABSTRACT FROM AUTHOR]

The density of a highly viscous polyelectrolyte solution was measured using both pycnometers and oscillating-tube densimeters in parallel to elucidate the difficulties inevitably involved when an oscillating tube is employed for density measurements of viscous liquids. It was confirmed that the oscillating-tube densimeter gives too high values for viscous liquids, and the deviation increases with the increase in the viscosity of liquids. The analysis of adiabatic compressibilities of sodium hyaluronate (NaHy) solutions, as estimated from density and ultrasound velocity data of the same solution, suggests that the disaccharide unit of the NaHy chain is less hydrated than the sum of its component monosaccharide residues. [ABSTRACT FROM AUTHOR]

The adsorption of bovine serum albumin (BSA) onto an anionic monolayer of sodium docosylsulfate (SDocS) spread at the air/water interface was studied by ellipsometry. The adsorption behavior of BSA was estimated from the observed changes in phase differences and in the ratio of reflection coefficients. The dynamic process of BSA adsorption was measured after the injection of BSA solution into the aqueous substrate of SDocS monolayer. The gentle stirring of the substrate solution for 10 min was found to be enough to make the solution homogeneous without damaging the monolayer. The adsorption characteristics of BSA onto a negatively charged surface was compared with that onto a positively charged surface previously reported. The amount of adsorption depended on time and showed a maximum with an initial rapid rise, followed by gradual decrease toward the ultimate equilibrium value. The amount and time of the maximum adsorption depended on the concentration of BSA added to the aqueous substrate. Separate radiotracer measurement, usingS-labeled SDocS monolayer, which is insoluble by itself, revealed that SDocS is solubilized into the bulk solution when BSA is added to the aqueous substrate. [ABSTRACT FROM AUTHOR]

The adsorption of bovine serum albumin (BSA) onto a cationic monolayer (N,N-dimethyl-N,N-dialkylammonium chloride) spread at the air/water interface was studied by ellipsometry. Both thicknesses and refractive indices of the BSA layer adsorbed at the monolayer/solution interface are estimated from the observed change in phase difference and the ratio of reflection coefficients. The amount of adsorption of BSA resembles a Langmuir type isotherm. The adsorption changes with pH asymmetrically with respect to the pH of maximum adsorption, which was calculated to be 5.06 ± 0.47 mg/m. The amount of maximum adsorption implies that the BSA molecule adsorbs to the surface in a mode intermediate between 'side-on' and 'end-on'. [ABSTRACT FROM AUTHOR]

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We carried out an electrolysis by changing the temperature from −80°C to room temperature in order to create a dynamic condition in the electrode. No neutron emission was observed from the palladium and the titanium electrodes in counting intervals from 28.6 ms to 267 h. The upper limit on neutron emission we obtained in palladium was 3.1·10 counts/d-d pairs/s for the counting interval of 124 h at 99.7% confidence level. [ABSTRACT FROM AUTHOR]

Equilibrium vapor pressure of water was measured for ionic surfactant-water binary systems as a function of water content over the temperature range 5-11°C. The measurement of x-ray powder diffraction has also been performed to characterize the microscopic structures of these two-component systems. Examined surfactants were the homologs of sodium alkyl sulfate and alkyltrimethylammonium bromide. It was found that dodecyl and decyl sulfate formed solid di-and trihydrate respectively, while octyl sulfate and the cationic surfactants formed lyotropic liquid crystal instead. The x-ray long spacing of the liquid crystals scarcely varied with water content.Enthalpy of vaporization was calculated for both solid hydrates and lyotropic liquid crystals. [ABSTRACT FROM AUTHOR]