Water site isolation

The use of direct electrochemical methods (cyclic voltammetry Pig. 17) has enabled us to measure the thermodynamic parameters of isolated water-soluble fragments of the Rieske proteins of various bci complexes (Table XII)). (55, 92). The values determined for the standard reaction entropy, AS°, for both the mitochondrial and the bacterial Rieske fragments are similar to values obtained for water-soluble cytochromes they are more negative than values measured for other electron transfer proteins (93). Large negative values of AS° have been correlated with a less exposed metal site (93). However, this is opposite to what is observed in Rieske proteins, since the cluster appears to be less exposed in Rieske-type ferredoxins that show less negative values of AS° (see Section V,B). 

Site isolation technology A method that attempts to isolate wastes and contaminated soils and sediments from their surrounding environments. Site isolation technologies include the use of barriers and clay caps to isolate landfills from contaminating surrounding groundwater, surface water, air, sediments, and soils. 

The isolated H2O molecules could be bound to the lattice by hydrogen bonds. The bonding between isolated water molecules and the icelike lattice is likely to occur at points where the crystalline structure presents protionic defects (empty or doubly occupied bonding sites). 

In a set of experiments designed to test site-isolation within the polystyrene matrix, Farrall and Frechet (1978) attempted to prepare the monoalkylated product of 1,4-butanedithiol. Large amounts of double coupling (dialkylation) were observed when the chloromethylated polystyrene used was reacted with excess sodium methoxide and 1,4-butanedithiol in DMF. Double coupling could be reduced substantially (to less than 5%) by employing a three-phase system consisting of (/iBu)4N OH" and 1,4-butanedithiol in a benzene-water solvent. 

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