Enzymatic method for determining oxygen solubility in perfluorocarbon emulsions

An enzymatic method to measure the glucose content in solution was adapted for measurements of oxygen content in oil in water emulsions with a precision of about 1%. The oxygen solubility in concentrated perfluorocarbon in water emulsions at 310.2 K and atmospheric pressure was measured. To study the effect of the perfluorocarbon and of the surfactant in the oxygen solubility, two perfluorocarbons, n-perfluorohexane and perfluorodecalin, in combination with three nonionic surfactants, Lecithin, Span 20 and Pluronic F-68 were used. The concentrations used were 50% (w/v) for the perfluorocarbons and 5% (w/v) for the surfactant. The oxygen solubility is shown to be independent of the surfactant used and dependent only of the perfluorocarbon employed in the emulsions studied.     

The solubility of toluene in aqueous salt solutions

The solubility of toluene has been measured in distilled water, and in various inorganic salt solutions. Values of the Setschenow constant, K(S), which quantify toluene solubility versus salt concentration, have been determined for each salt. Values of K(S) are compared to the activity of water for the salt solutions. Data from this study, consistent with earlier data, suggests that the effects of salts upon toluene solubility are non-additive. This contrasts the additive behavior of inorganic salts upon the solubility of nonpolar organic compounds, such as benzene and naphthalene, reported in the literature. Specific interaction between slightly polar toluene and ions in solution is suggested as a possible explanation for the non-additive effect of salts on the solubility of toluene.     

The solubility of oxygen in highly fluorinated liquids

Solubility of gases, especially oxygen, in fluorocarbons has achieved important status because of the latter's probable utility in artificial blood and liquid breathing, but only diverse data determined by various methods is scattered throughout the literature and company technical reports. One method, gas chromatography, was used to calculate and compare the oxygen and air solubility of a large number of fluorocarbons. Correlations were made between the oxygen solubilities and some of the physical properties of the compounds. Likewise, solubilities calculated using some lower parachor values resulted in a fairly good correlation.     

Dependence of the solubility of atmospheric oxygen in weakly alkaline aqueous solutions on surfactant concentration

The solubility of atmospheric oxygen in solutions of surfactants of different natures at 293 K and pH 8 is determined by gas chromatography. It is found that additives of nonionic surfactants decrease the oxygen content in the solution in the premicellar region and increase its solubility in the micellar region. It is shown that, for anionic surfactants, a decrease in the solubility of O₂ is observed over the entire concentration range.     

The acidity and solubility constants of tetracyclines in aqueous solutions

Solubility measurements over the pH range 2.6–7.6 for tetracycline, chlortetracycline, dimethylchlortetracycline and oxytetracycline are used to determine thermodynamic values for the solubility constant and the first and second acidity constants of these compounds.     

Estimation of aqueous solubility in drug design

The solubility of drugs in water is of central importance in the process of drug discovery and development from molecular design to pharmaceutical formulation and biopharmacy. The ability to estimate the aqueous solubility and other properties of a promising lead compound affecting its pharmacokinetics is a prerequisite to rational drug design, although it has received much less attention than the prediction of drug-receptor interactions. In this review, methods for the estimation of aqueous solubility of organic compounds are described and limited to approaches, which might be used in the early stage of drug design and development.     

The solubility of argon in aqueous solutions of a complex-ion electrolyte

From measurements of the solubility of argon in aqueous solutions of the complexion electrolyte t-[Co(en)₂NCSCl]Br at 25°C, the Setschenow parameter for this system is found to be +0.33₆. Using the scaled-particle theory of the salt effect with this value ofk ₅ and the Waddington crystal radius of the Br^– ion, 1.98 Å, the radius of the complex cation is calculated to be 3.71 Å. This value is in reasonably good agreement with that estimated from scale models of the t-[Co(en)₂-NCSCl]⁺ cation, about 3.9 Å. It is somewhat larger than the radius calculated from various semiempirical equations relating the molal volume of an ion at infinite dilution to its radius; values of r obtained in this manner range from 3.32 to 3.66 Å.Abstracted, in part, from D.P.'s M.S. thesis, June 1971.     

Phase behavior and microstructures of nonionic fluorocarbon surfactant in aqueous systems

The phase behavior and self-assembled structures of perfluoroalkyl sulfonamide ethoxylate, C8F17SO2N(C3H7)(CH2CH2O)20H (abbreviated as C8F 17EO20), a nonionic fluorocarbon surfactant in an aqueous system, has been investigated by the small-angle X-ray scattering (SAXS) technique. The C8F17EO20 forms micelles and different liquid crystal phases depending on the temperature and composition. The fluorocarbon micellar structure induced by temperature or composition change and added fluorocarbon cosurfactant has been systematically studied. The SAXS data were analyzed by the indirect Fourier transformation (IFT) and the generalized indirect Fourier transformation (GIFT) depending on the volume fraction of the surfactant and complemented by plausible model calculations. The C8F17EO20 forms spherical type micelles above critical micelle concentration (cmc) in the dilute region. The micelle tends to grow with temperature; however, the growth is not significant on changing temperature from 15-75 degrees C, which is attributed to the higher clouding temperature of the surfactant (>100 degrees C). On the other hand, the micellar structure (shape and size) is apparently unaffected by composition (1-25 wt %) at 25 degrees C. Nevertheless, addition of fluorocarbon cosurfactant of structure C8F17SO2N(C3H7)(CH2CH2O)H (abbreviated as C8F17EO1) to the semidilute solution of C8F17EO20 (25 wt %) favors micellar growth, which finally leads to the formation of viscoelastic wormlike micelles, as confirmed by rheometry and supported by SAXS. The onset sphere-to-wormlike transition in the structure of micelles in the C8F17EO20/water/C8F17EO1 system is due to the fact that the C8F17EO1 tends to go to the surfactant palisade layer so that the critical packing parameter increases due to a decrease in the effective cross-sectional area of the headgroup. As a result, spherical micelles grow into a cylinder, which after a certain concentration entangle to form a rigid network structure of wormlike micelles.     

碳氟-碳氢表面活性剂混合水溶液在油面上铺展

本文研究RfCONH(CH2)3N(C2H5)2CH3I/CnH2n 1,COONa及RfCOONa/CmH2m 1N(CH3)3Br(Rf=F[CF(CF3)CF2O]2CF(CF3);n=7,8.11,13;m=8,10,12)两类正，负离子碳氟－碳氢表面活性剂混合水溶液在油面上的铺展及对油面的密封性能。研究表明在碳氟表面活性剂中加入异电性碳氢表面活性剂可大大降低碳氟表面活性剂水溶液的铺展浓度，也可使一些因素表面张力较高而不能铺展的碳氟表面活性剂水溶液在油面上铺展。在碳氟表面活性剂中加入异电性碳氢表面活性剂可提高水膜对油面的密封性。若在混合表面活性剂中加入黄原胶，水膜的密封性能更好。     

Ozone solubility in concentrated aqueous solutions of salts

The effect exerted by the concentration of salts (NaCl, Na₂SO₄, and NaNO₃) on the ozone solubility in aqueous solution at 20, 30, and 40°C was studied. The solubility coefficients of ozone were calculated. The Henry constants and the Sechenov coefficients were determined.     

Rate enhancement of Diels-Alder reactions in aqueous perfluorinated emulsions

A marked acceleration property for the Diels-Alder reaction was observed in an aqueous micellar system composed of perfluorohexane and lithium perfluorooctanesulfonate. The reaction rate increased with the concentration of the equimolar mixture of PFH and LiFOS, and the rate in 500 mM PFH and 500 mM LiFOS was about 100-fold greater than that in water without the fluorous field. After completion of the reaction, the products were simply extracted from the aqueous reaction mixture using n-hexane. [reaction: see text].     

The solubility of (14)C-labelled barium carbonate in aqueous systems

The solubility of (14)C-labelled barium carbonate has been determined in basic aqueous solutions with and without added Ba(2+) present and in aqueous solutions containing no added Ba(2+) or OH(-) ions. By use of activity coefficients from the literature, K(sp) has been determined to be 4.0 x 10(-10) +/- 0.5 x 10(-10) at 25 degrees .     

The solubility of disperse dyes in an aqueous sodium dodecyl sulfate solution

Summary The solubilities of the following compounds in an aqueous sodium dodecyl sulfate solution were determined at 25°, 30°, 35° and 40°C: biphenyl, azobenzene, p-chloroazobenzene, p-aminoazobenzene, p-N,N-dimethylaminoazobenzene and p-nitroazobenzene. From the results the thermodynamic parameters for the transfer of the model compounds from water to SDS micellar environment were calculated. The resulting thermodynamic parameters were not so certain, but suggested that with biphenyl, azobenzene and p-chloroazobenzene which seem to be solubilized in the SDS micellar interior the solubilizing process is a result of a favourable increase in entropy, and that with p-aminoazobenzene, p-N, N-dimethylaminoazobenzene and p-nitroazobenzene which seem to be solubilized in the SDS micellar surface the solubilizing process is a result of a favourable decrease in enthalpy. The favourable increase in entropy was explained in terms of iceberg and the favourable decrease in enthalpy in terms of interfacial energy.     

The effect of cyclodextrin mixtures on aqueous solubility of beclomethasone dipropionate

The aim of present study was to evaluate the effect of natural, synthetic cyclodextrins (CDs) and CD mixtures on aqueous solubility of beclomethasone dipropionate (BDP). The phase solubility studies were done in the presence of 6 CDs. Furthermore, aqueous solubility of BDP was tested in the presence of CD mixtures. The solubility of BDP in water was increased by 30, 77, 155 and 30 folds in the solution containing 20%?w/v α-CD, hydroxylpropyl β-CD (HP-β-CD), hydroxypropyl γ-CD (HP-γ-CD) and sulphobutylether β-CD (SBE-β-CD), respectively. CD mixtures had remarkable effect on the aqueous solubility of BDP so that solubility in water increased between 200 and 1,500 times in the presence of different CD mixtures. Further addition of sodium acetate to the solubilisation medium reduced the aqueous solubility. In conclusion, CD complexation was able to improve the aqueous solubility of BDP. The synergistic effect of cyclodextrin mixture was observed.     

Investigation of solubility of microcrystalline cellulose in aqueous NaOH

A cost‐effective and environmentally friendly method to dissolve microcrystalline cellulose (MCC) has been utilized. A detailed investigation of the effects of cellulose amount and solvent (aqueous NaOH) concentration on MCC solubility has been presented. In the experiments, NaOH solutions with concentrations ranging from 3.7 to 18.6 wt% have been employed to dissolve MCC with various weights. The results show that an optimal NaOH concentration range can always be found to give the best solubility of MCC having a certain weight. The solubility monotonically decreases with either the decreasing or increasing of NaOH concentration away from the optimal concentration range. In addition, the optimal concentration range of NaOH for dissolving cellulose has been shown to shrink as the amount of MCC increases. Copyright © 2005 John Wiley & Sons, Ltd.     

The solubility and kinetics of decomposition of ozone in aqueous solutions of nitrates

The influence of the concentration of NaNO₃ on the solubility of ozone in water was studied at 20, 30, and 40°C. The solubility coefficients of ozone were calculated, and the Henry constants and Sechenov coefficients determined. The Sechenov coefficients (K _c ) were found to decrease insignificantly as the temperature increased. The kinetics of dissolved O₃ transformations was analyzed. The decomposition of ozone was described by a pseudofirst-order equation with respect to salt concentration. The rate constant (k _c ) for the decomposition of ozone in the presence of NaNO₃ was found to be 3.5 × 10^?4 l mol^?1 s^?1.     

Steric repulsion between internal aqueous droplets and the external aqueous phase in double emulsions

A theoretical model for analyzing the steric repulsion energy between internal aqueous droplets and the external aqueous phase in double emulsions, which results from the steric interaction between the surfactant molecules adsorbed at the two interfaces, has been established. The steric interaction is dependent on the separation distance between the internal aqueous droplets and the external aqueous phase, the thicknesses of the two adsorbed surfactant layers, and the size of the internal aqueous droplets and the oil globules, all of which determine the extent of the compression of the adsorbed surfactant molecules. The thickness of each of the two surfactant layers have the same effect on the steric repulsion, and stronger steric interaction can be achieved with thicker adsorbed layers, which can effectively prevent coalescence between the internal aqueous droplets and the external aqueous phase. Increasing the internal aqueous droplet size can produce stronger steric repulsion; however, larger oil globules will weaken the steric repulsion, indicating that a more stable double-emulsion system can be achieved by preparing the system with smaller oil globules and larger internal aqueous droplets.