Mixed Solid Phases

Combinatorial chemistry has significantly increased the nurnjjers of molecules that can be synthesised in a modern chemical laboratory. The classic approach to combinatorial synthesis involves the use of a solid support (e.g. polystyrene beads) together with a scheme called split-mix. Solid-phase chemistry is particularly appealing because it permits excess reagent to be used, so ensuring that the reaction proceeds to completion. The excess... 

Hicks (H6) and Frazer and Hicks (F3) considered the ignition model in which exothermic, exponentially temperature-dependent reactions occur within the solid phase. Assuming a uniformly mixed solid phase, the one-dimensional unsteady heat-flow equation relates the propellant temperature, depth from the surface, and time by the nonlinear equation ... 

Another mixture problem is how to deal with mixed solid-phase gas hydrates. Both methane and carbon dioxide form structure I gas hydrates. Thus CH4-CO2 gas mixtures will ultimately lead to CH4-CO2 gas hydrates. Equilibria for the simple gas hydrates can be represented by... 

Insofar as the soil solution is concerned, the principal effect of coprecipitation is on the solubility of the elements in the solid. If the soil solution is in equilibrium with a mixed solid phase, for example, the activity in the aqueous phase of an ion that is a minor component of the solid may be significantly smaller than what it would be in the presence of a pure solid phase comprising the ion. This effect can be deduced from Eq. 3.3 after noting that (MJLb) < <... 

The existence of mixed solid phases in which the trace ion lowers its solubility by co-precipitating into another component. 

Kurnik and Reid (1982) also use the Peng-Robinson EOS to correlate their data on the solubility of two pure solids in an SCF solvent. Their results are very sensitive to the value of the binary solidi-solid2 interaction parameter they use. Gopal et al. (1983) found similar results. They show that calculated solid solubilities are dependent on whether the mixture consists of two pure solids or whether the solids have melted and formed a single mixed-solid phase. 

As the temperature is lowered further, additional pure ethyl benzene precipitates out and the liquid becomes richer in toluene, until the eutectic composition and temperature is reached. At this point all the remaining liquid solidifies as two mixed solid phases. 

Surface dissolution of the support and formation of mixed solid phases [10]... 

The value of - the slope of the metal solubility as a function of pH - is often found to be between -0.5 and -0.7 for Cd + and (McBride et al., 1997 Salam and Helmke, 1998 Gray et al., 1999 Sauve et al., 2000). If we take —0.67 as a reasonable value for Cd, then metal solubility will show a 2 3 dependence on soil solution pH. This can be handled by having GEOCHEM-PC consider the formation of a mixed solid phase with a mythical soil ligand, the MSL ... 

Recent reviews discuss the latest developments in DOS, which provide various examples leading to natural-like compound libraries (Cordier et al., 2008 Marcaurelle and Johannes, 2008). The split-mix solid-phase synthesis technology developed by Furka (Furka et al., 1991) is particularly useful for library generation using fhe DOS strategy leading to over a million members of libraries as mixtures. 

MSPD is the next alternative for sample preparation of fruits, vegetables, herbs, cereals, and other plants. It is convenient for liquid and semi-liquid samples. This technique is a multi-residual assay which consists of matrix homogenization with a solid silica phase placed into a short column, as in SPE. Analytes and matrix interferences are retained on the mixed solid-phase material with completely new separation characteristics. Specific elution allows one to obtain analytes after the elimination of matrix compounds via washing steps. This... 

Heidemann RA Wax precipitation modeled with many mixed solid phases, AlCHE J 51(l) 298-308, 2004. 

By definition, iron containing between 0.15 and 1.4 wt.% C is typically referred to as steel.Hence, although we typically think of steel as containing chromium and other metal dopants, some y- and 5-phases of pure iron could also be considered forms of steel. Steels with a carbon concentration of 0.83 wt.% undergo a transformation from austenite into two intimately mixed solid phases at a temperature of 723°C. Although this phase transformation looks like a eutectic, the material above... 

At higher degrees of conversion an additional complication arises. Since it was assumed that the reaction product forms a mixed solid phase with the reactant in which the reaction takes place, a concentration gradient of that reactant will appear, that will change with time. 

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