Ca oxalate was crystd. in the presence of the anionic surfactant diisooctyl sulfosuccinate, AOT, and the phase compn. of the ppts. (by x-ray diffraction powder patterns and thermal anal.) and their crystal growth morphol. (by SEM and electron diffraction) were detd. In the control systems and in the presence of low concns. of AOT (below the crit. micellar concn., CMC) Ca oxalate monohydrate (CaC2O4·H2O, COM) was the dominant crystal phase. Crystals grown in the presence of C(AOT)\textgreater0.75 CMC were thinner and more elongated than in the controls, indicating preferential adsorption of the surfactant at the 1̅01 and \010\ crystal faces. When the AOT concn. exceeded the crit. micellar concn., the morphol. changes in COM crystals became more intense and the compn. of the ppts. abruptly changed to mixts. of COM and Ca oxalate dihydrate (CaC2O4·(2+x)H2O, x\textless0.5; COD) with a COM/COD ratio up to 50%. The morphol. of the COD crystals was mostly unaffected. The phase change was attributed to preferential adsorption of AOT - as surface aggregates - at the crystal faces of COM with the consequence of strong inhibition of nucleation and crystal growth of this crystal type and growth of the kinetically less favored COD crystals. [on SciFinder(R)]

The results of an extensive study of percolation to verify some theor. predictions about percolation crit. indexes for changes in static and dynamic dielec. properties of a microemulsion a a function of temp. and frequency are presented. The dynamic behavior of the microemulsions was also studied to reveal the mechanisms that are responsible for dielec. polarization of the system. The measurements were made by the time domain dielec. spectroscopy method in the frequency range 105-1010 Hz and at 10-40°. Crit. indexes for cond. and dielec. permittivity have the values s ≈ 1.2 below and t ≈ 1.9 above the percolation threshold. The value for the crit. index s is in agreement with a dynamic percolation picture. This confirms the idea that the mechanism responsible for the temp. dependence of cond. and permittivity has the same origin. The numerical value of t indicates a percolation picture above the threshold; however, it does not provide information about the nature of percolation. The data treatment for the dynamic behavior of the microemulsions was carried out in the time domain in terms of dipole correlation functions. The correlation functions exhibit complex nonexponential relaxation behavior in the percolation region and must be deconvoluted into normal modes and represented as the sum of the simple exponential exp(-t/$\tau$) and nonexponential terms exp[-(t/$\tau$)$\beta$]. The frequency scaling parameters m, p, and u, as well as the stretched parameters in the time window $\beta$, provide information about the microstructure and dynamics of the system. The anal. of their temp. dependence shows the existence of spatial, temporal, and energetic disorder assocd. with anomalous diffusion of charge carriers in the percolation clusters. From a detailed anal. of the time relaxation data spectrum, the mol. dynamic mechanism of dielec. polarization in the percolation region was suggested. [on SciFinder(R)]

Calcium oxalate dihydrate (CaC2O4.(2+x)H2O; COD; x less than or equal to 0.5) does not readily crystallize from electrolytic solutions but appears as a component in crystalluria. In this paper, we review in vitro studies on the factors responsible for its nucleation and growth with special attention given to the role of surfactants. The following surfactants were tested: dodecyl ammonium chloride (cationic), octaethylene mono-hexadecylether (non-ionic), sodium dodecyl sulfate (SDS, anionic), dioctyl sulphosuccinate (AOT, anionic), and sodium cholate (NaC, anionic). The cationic and some of the anionic surfactants (SDS, AOT) induced different habit modifications of growing calcium oxalate crystals by preferential adsorption at different crystal faces. In addition, the anionic surfactants effectively induced crystallization of COD at the expense of COM, the proportion of COD in the precipitates abruptly increasing above a critical surfactant concentration, close to, but not necessarily identical with the respective CMC. A mechanism is proposed, whereby crystallization of COD in the presence of surfactants is a consequence of the inhibition of COM by preferential adsorption of surfactant hemimicelles (two-dimensional surface aggregates) at the surfaces of growing crystals.

The BSO (V. Bansal, D. Shah, and J. O'Connell, 1980) equation was derived as an empirical condition for max. H2O solubilization in microemulsions stabilized by anionic surfactants, in relation to the cosurfactant (alc.) and oil chain lengths. The present study examines, for the 1st time, the applicability of this equation for nonionic microemulsions. By constructing pseudo-ternary phase diagrams and measuring the area of the single phase regions as well as the H2O contents at the boundary, the authors find the solubilization capacity is related directly to the alc. chain length only if the alc. soly. in both the aq. and oleic phases is limited. In addn., the authors try to integrate the concept of chain length compatibility with the competition between the natural curvature and the crit. radius of the interface. The attempt to unify the exptl. results may serve as a guideline for optimization of microemulsion systems. [on SciFinder(R)]

In search for tomorrow's technol. for water-based coatings, Decora Manufg. and The Hebrew University of Jerusalem, have initiated an intensive research program for designing, developing and manufg. new coatings based on crosslinked, room-temp.-cured silicone-epoxy resins. The new water-borne coatings have most exciting characteristics such as: non-stick properties, effective release, high lubricity, corrosion protection and abrasion resistance. The coatings are environmentally friendly and easy to use. These coatings are ideal for marine, agricultural, industrial and maintenance applications. This paper brings quant. measurements related to the dispersion technol. (particle size, stability, shelf-life), to the non-stick properties (deicing, low surface energy, easy-release and non-stick), lubricity, adhesion to substrates, viscosity, dynamic and static friction coeffs. and environmental impact (low VOC, non-toxicity, low-leaching). The coating was tested in various industrial coating systems and was found to exhibit excellent non-stick and release properties. Special attention was given to Zebra Mussels, Quagga Mussels, and other bacterial and algal bioforms. The coating proved to be efficient as foul-release coating with very low biofouling adhesion. The low adhesion applied to many other substances in which foul-release means easy-clean and low wear. [on SciFinder(R)]

A process for the removal of a cholesterol from liq. or liquefiable edibles, by hydrocolloid extractants, preferably galactomannose, is disclosed. [on SciFinder(R)]

The invention provides a water-in-oil microemulsion having a high fire resistance, consisting of mineral oil; at least 50% water; and at least one polyethoxylated nonionic alc. surfactant, the alc. having 12-18 carbon atoms and having attached thereto between 2 and 25 ethoxy groups. [on SciFinder(R)]

A polymorph of aspartame, designated APM II, characterized by X-ray diffraction powder patterns, an IR diffraction pattern, and differential scanning calorimetric patterns, was prepd. Thus, aspartame was crystd. from a pH 5.3 buffer prepd. from potassium hydrogen phthalate and NaOH in H2O at 21° to give APM II. Sweetening compns. contg. APM II are claimed. [on SciFinder(R)]

Fenugreek saponins have improved properties as compared to soybean saponins when used as emulsifiers. Thus, comestible products may contain emulsifying fenugreek saponins selected from tigogenin, neotigogenin, gitogenin, neogitogenin, diosgenin, yamogenin, yuccagenin, and lilagenin. [on SciFinder(R)]

Cationic guar gums of varying molar mass and charge d. were synthesized and tested as flocculants for bentonite suspensions. The gums were fragmented using ammonium persulfate as a degrading agent, followed by pptn. of the products with ethanol. Cationic charge was added to the guar mol. by reacting it with 2,3-epoxypropyltrimethylammonium chloride. Flocculant performance was assessed by detg. the extent of polymer adsorption, by measuring both residual turbidities of the resulting supernatants and the changes in the particles' electrophoretic mobility (EM). Increasing the flocculant charge d. causes the optimal flocculation concn. (OFC), as well as the efficient flocculant concn. range, to be reduced. Above this range restabilization occurs. The OFC (for highly modified guar) is also the concn. at which the particles' EM is zero. It was found that decreasing the mol. wt. of the guar (at the same charge d.) increases the OFC and decreases the electrophoretic mobility of the clay particles in the overdose range. [on SciFinder(R)]

Silicone based surfactants were used as stabilizers for W/O/W double emulsions with unusual mech. stability. W/O/W multiple emulsions contg. several markers were prepd. The entrapped markers were: (1) halide salts, (2) a typical drug, ephedrine hydrochloride, and (3) KNO3 (water sol. fertilizer). Good solute trapping (95% yield of prepn.) with slow release rates through the liq. oil membrane (60% release after 30 days), were obtained. The halides, with the exception of iodide, showed almost the same typical slow release rates to the outer water phase. The release rates of the ephedrine hydrochloride and KNO3 were faster than that of the halides. The results suggested that multiple emulsions based on silicone surfactants can be used as slow release systems for agricultural applications. Up to 20 wt% of the total concn. of the hydrophobic silicone-based emulsifier (E1 - the inner emulsifier) was replaced by Span 80. As a result, water was entrapped in the oil phase, suggesting formation of reverse micelles in the presence of Span 80, explaining, in part, the release kinetics of the halides. The release seems to be composed of three sep. stages: lag time, fast release and "no release". The release mechanism seems to comply, in part, with a transport mechanism involving "reverse micelles" and is also dependent on the hydrophobicity of the marker. The more hydrophobic markers (the drug and iodide) seem to be released also by "direct diffusion of the mol. through the oil" in addn. to their release through the reverse micelles. [on SciFinder(R)]