Ternary systems experimental techniques

An experimental complication is the difficulty in effecting molecular interaction between the components. The usual technique for preparing lipid-protein phases in an aqueous environment is to use components of opposite charge. This in turn means that the lipid should be added to the protein in order to obtain a homogeneous complex since a complex separates when a certain critical hydrophobicity is reached. If the precipitate is prepared in the opposite way, the composition of the complex can vary since initially the protein molecule can take up as many lipid molecules as its net charge, and this number can decrease successively with reduction in available lipid molecules. It is thus not possible to prepare lipid— protein—water mixtures, as in the case of other ternary systems, and to wait for equilibrium. Systems were prepared that consisted of lecithin-cardiolipin (L/CL) mixtures with (a) a hydrophobic protein, insulin, and with (b) a protein with high water solubility, bovine serum albumin (BSA). 

An experimental study on the oxidation of alloys containing 0-9 mass% Cr and 0-1 mass% Si in carbon dioxide at 500°C has been reported by [1982Mos], Several experimental techniques were used for this investigation (X-Ray, TEM, SEM, Photoelectron microscopy), fliey studied flic silicon distribution in the alloys and compared the results with theoretical predictions by an oxidation model. An attempt to grow materials with a eutectic composition in this ternary system by directional soUdrfication was made by [1978Hao]. However, the alloys were found to have no eutectic. 

In ord to optimize the applications of SSI technique different problems should be solved with the help of experimental determinations coupled widi some theoretical analysis. It is obvious that the polymer in contact with the supercritical fluid swells (the CO2 dissolves in the polymer) and the extent of swelling depends from the pressure. When the polymer is in contact with the supercritical fluid saturated with the pharmaceutical the solvent again diffuses in the polymer, it swells the polymer and in this way the solubilization of the drug in the polymer is fricilitated. As a consequence in addition to the kinetic problems (diffusion in the polymer matrix) the thermodynamic description of the ternary systems, supa critical fluid, pharmaceutical and polymer, is essential. 

Although as described above fliese alloy systems have been studied by a number of research groups, it is difficult to directly compare one system to another because of differences between sample preparation methods and experimental techniques. Such multielement comparisons do not appear routinely in the literature because flic amount of work involved in sample preparation and testing using traditional one at a time mefliods is prohibitive. Thus, a paper published by Stevens et al. [235] demonstrated flic usefijlness of composition spread preparation and analysis techniques for fuel ceU catalyst research. Furthermore, performance measurements of Pti composition were used to identify more complex ternary or quaternary composition for future studies. 

The experimental technique is that of the unidimensional scan as follows. Series of surfactant-oil-water systems are prepared, all with identical composition (same amounts of surfactant, oil, aqueous phase, and alcohol, typically selected so that the representative point is in the polyphasic region of a ternary diagram, i.e., 3% surfactant and equal proportions of oil and water) and all with the same formulation, with the exception of the scanned variable. This is, in general, the aqueous-phase salinity for ionic systems and the average number of ethylene oxide groups per molecule (EON) if the systems contain an ethoxylated nonionic surfactant mixture. 

Although there is a large number of experimental data (1, 2.,.3) for ternary aqueous electrolyte systems, few equations are available to correlate the activity coefficients of these systems 1n the concentrated region. The most successful present techniques are those discussed by Meissner and co-workers (4 ) and Bromley ( )... 

Emphasis has already been placed on the different experimental methodologies, for instance by Hume-Rothery et al. (1953) who stressed the need to use different complementary techniques in the definition of ternary or more complex systems. The necessity of combining thermal analysis with microscopic techniques was especially highlighted, for example, in the determination of solid liquid equilibria. 

Recently a fairly inexpensive way of high-temperature experimentation has been found to investigate refractory sulfides and related multicomponent systems up to temperatures of nearly 2000 °C using resistance furnaces. These techniques are discussed below and applied to some sulfide systems, in particular of those metals which belong to the VI-B group. The binary systems chromium-sulfur, molybdenum-sulfur, tungsten-sulfur, as well as some other ternary and quaternary systems and their reactions are reviewed and completed within the limits of the new experimental procedure. 

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