Species-specific regions

The physicocheimcal basis for separation is the primary focus of Chapter 3. Separation happens via species-specific force driven relative displacement of molecules of one species in relation to other species into species-specific region in the separation system. Particles of different sizes/ properties similarly undergo relative displacements. To develop this perspective. Chapter 3 (Section 3.1) identifies various external forces and chemical potential gradient based... 

We have now developed a quantitative understanding of the movement of specific molecular species (or particles) in a given direction at a particular speed under the action of a negative chemical potential gradient and/or external forces. Suppose a mixture to be separated is located in a closed container identified as the separation system and subjected to a particular force (or forces). It should now be possible to follow the displacement characteristic of each species in the mixture. For chemical solutions, such displacements are conveniently studied by following the spatial and temporal variations of concentration of any species we seek to find out how Q varies with time t and the spatial coordinates x, y, z. Development of species-specific regions necessary for the separation of a mixture can then be observed first by considering the relative spatial locations of concentration maxima of each individual species. 

The study of biochemical natural products has also been aided through the application of two-dimensional GC. In many studies, it has been observed that volatile organic compounds from plants (for example, in fruits) show species-specific distributions in chiral abundances. Observations have shown that related species produce similar compounds, but at differing ratios, and the study of such distributions yields information on speciation and plant genetics. In particular, the determination of hydroxyl fatty acid adducts produced from bacterial processes has been a successful application. In the reported applications, enantiomeric determination of polyhydroxyl alkanoic acids extracted from intracellular regions has been enabled (45). 

A. Bubert, S. Kohler, and W. Goebel, The homologus and heterologous regions within the lAP-gene and genus-specific and species-specific identification of Listeria by polymera.se chain-reaction. Appl. Environ. Microbiol.. 5S 2632 (1992). 

Shastry, M., Nielsen, J., Ku, T., Hsu, M. J., Liberator, P., Anderson, J., Schmatz, D., and Justice, M. C. (2001). Species-specific inhibition of fungal protein synthesis by sordarin Identification of a sordarin-specificity region in eukaryotic elongation factor 2. Microbiology 147, 383-390. 

It is useful at this point to differentiate among the ways in which we can define equilibrium. In a classic sense (e.g., Pitzer and Brewer, 1961 Denbigh, 1971), a system is in equilibrium when it occupies a specific region of space within which there is no spontaneous tendency for change to occur. In this case, which we will call complete equilibrium, all possible chemical reactions are in equilibrium. Assuming complete equilibrium, for example, we can predict the distribution of dissolved species in a sample of river water, if the water is not supersaturated with respect to any mineral. 

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