Multivalent banks

Sequential protocols in which one starts with a range of multivalent banks, and works towards higher affinities with monovalent libraries, mutational libraries or extension libraries, derived from the enriched clones, have been shown to be highly effective (e g. Refs. 33, 85 and 94). This and the evolutionary approach in highly mutagenic E. coli hosts over many selection rounds (e.g. Ref. 41) will surely influence further experimental design. 

A. Dondoni, M. Kleban, X. Hu, A. Marra, and H. D. Banks, Glycoside-clustering round calixarenes toward the development of multivalent carbohydrate ligands. Synthesis and conformational analysis of calix[4]arene O- and C-glycoconjugates, J. Org. Chem., 67 (2002) 4722 -733. 

It is apparent from the table that the phase behavior of the system under discussion is much more sensitive to the multivalent cation concentration at low surfactant concentrations than at high surfactant concentrations. This means that the exact ionic composition of the brine in the surfactant bank is more critical near the end of a chemical flood than it is in the beginning. It means also that the effect of ion exchange on the phase behavior and, hence, on the oil displacing activity of the surfactant-brine-oil system becomes more pronounced as the chemical flood proceeds. 

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