Hill solution composition

Figure 16.3. Enthalpy-composition diagrams of some salt solutions. Several other diagrams are in the compilation of Landolt-Bomstein, IV 4b, 1972, pp. 188-224. (a) sodium sulfate/water (b) magnesium sulfate/water (after Chemical Engineers Handbook, 1963 edition, McGraw-Hill, New York) (c) sodium carbonate/water.

The modification of Schreinemakers wet residue method which was used in this part of the investigation is that instead of analyzing the wet residue, a complex is prepared of known composition and the solution only is analyzed. This again gives two points on the diagram the solution point on the curve and the complex point which replaces the wet residue point. Hill and Ricci (7) claim that the complex method is as accurate or more accurate than the residue method if algebraic extrapolation of the tie-lines is used. 

The most unpredictable process in X-ray structure determination is the crystallization of the candidate protein into a form suitable for X-ray diffraction. Each protein requires a unique set of conditions to form crystals. Typically 100 mg of highly purified protein is required to determine the conditions that result in usable crystals of 0.1 to 0.3 mm size, although a size of 0.3 to 0.8 mm is preferred. The occurrence of crystals and the rate of crystallization are influenced by many factors such as protein purity, the solvent, concentration of added precipitants, pH, temperature, and the presence of ions and cofactors. The protein solution at a concentration of typically 5 to 20 mg/ml is allowed to slowly reach supersaturation by the removal of or by changing the composition of the solvent by liquid-liquid diffusion or vapor diffusion methods. Microscale methods have been developed to explore several crystallization conditions simultaneously using minimum amounts of the purified protein sample. Recently, use of the zero gravity atmosphere in space has been explored as a means of facilitating crystallization (Eisenberg and Hill, 1990 Branden and Tooze, 1991 Tomasselli et al, 1991). 

In 1957 Hill introduced a binary solution theory based on an analysis of the semigrand partition function in which the pressure P, temperature T, and number of solvent particles, Nj, are held fixed (10, 11). In this section, we extend his derivation to a four-component system containing solvent (component 1), two polymers (components 2 and 3) and protein (component 4). The objective of the calculation is to derive expressions for the chemical potentials of all components. Later, by equating the chemical potentials of each component in each phase, we will determine the composition of each phase and hence the protein partition coefficient which is defined to be the ratio of protein compositions in the top and bottom phases. 

Small batches ( 10 g) of powders were prepared by the glycine-nitrate process (GNP) [5], Appropriate amounts of metal salts (barium-, cerium-, yttrium-, and zirconyl nitrates, ammonium cerium [IV] nitrate, and barium acetate were [Alfa Aesar, Ward Hill, MA]) and glycine were dissolved in deionized water. The solution was heated on a hot plate in a stainless steel beaker until a sufficient amount of solvent had evaporated allowing the precursor to ignite. The resulting ash was sieved (100-mesh) and calcined for 20 min to 30 min at 1,200°C to produce the desired single-phase perovskite. Additional material was obtained commercially (Praxair). The following compositions were synthesized ... 

The Fluctuation Theory of Solutions—also known as Fluctuation Solution Theory, Kirkwood-Buff Theory, or simply Fluctuation Theory— provides an elegant approach relating solution thermodynamics to the underlying molecular distributions or particle number fluctuations. Here, we provide the background material required to develop the basic theory. More details can be found in standard texts on thermodynamics and statistical mechanics (Hill 1956 Munster 1970). Indeed, the experienced reader may skip this chapter completely, or jump to Section 1.2. A list of standard symbols is also provided in the Prolegomenon to aid the reader, and we have attempted to use the same set of symbols and notations in all subsequent chapters. Throughout this work we refer to a collection of species (1, 2, 3,...) in a systan of interest. We consider this to represent a primary solvent (1), a solute of interest (2), and a series of additional cosolutes or cosolvents (3,4,...) which may also be present in the solution. However, other notations such as A/B or u/v is also used in the various chapters. All summations appearing here refer to the set of thermodynamically independent components (n in the mixture unless stated otherwise. Derivatives of the chemical potentials with respect to composition form a central component of the theory. The primary derivative of interest here is defined as... 

Coupling agent n. A chemical capable of reacting with both the reinforcement and the resin matrix of a composite material to form or promote a stronger bond at the interface. The agent may be apphed from the gas phase or a solution to the reinforcing fiber, or added to the resin, or both. Harper CA (ed) (2002) Handbook of plastics, elastomers and composites, 4th edn. McGraw-Hill, New York. 

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