Activity coefficient analytical representation

Up to this point, GIPF expressions have been formulated for only one type of biological activity - the inhibition of reverse transcriptase (RT), the enzyme that promotes the reverse transcription of genomic RNA into double-stranded DNA, a key step in the replication of the human immunodeficiency virus, HIV [82, 87]. Analytical representations were obtained for the anti-HIV potencies of three families of RT inhibitors the correlation coefficients are between 0.930 and 0.952. We are currently investigating the effects of applying the GIPF approach to certain portions of the molecules rather than their entireties. This might reveal the source of the activity, or alternatively, indicate it to be delocalized. 

Analytical representation of the excess Gibbs energy of a system impll knowledge of the standard-state fugacities ft and of the frv. -xt relationshi Since an equation expressing /, as a function of x, cannot recognize a solubili limit, it implies an extrapolation of the /i-vs.-X[ curve from the solubility I to X) = 1, at which point /, = This provides a fictitious or hypothetical va for the fugadty of pure species 1 that serves to establish a Lewis/ Randall 1 for this species, as shown by Fig. 12.21. ft is also the basis for calculation of activity coefficient of species 1 ... 

The Hiickel equation (41.13), appropriately adjusted to give 7m, has been frequently employed for the analytical representation of activity coefficient values as a function of the ionic strength of the solution, and various forms of the Debye-HOckel and Br nsted equations have been used for the purpose of extrapolating experimental results. Some instances of such applications have been given earlier ( 39h, 39i), and another is described in the next section. 

Equilibrium phenomena of liquid and vapour phases of binary and ternary mixtures, as well as the analytical and graphic representation of the equilibrium of the two phases have been discussed in the introduction written b) Hausen. The introduction also contains discussion of the thermodynamic basis of phase equilibria, definitions of the characteristic concepts of the activity coefficient and the fugacity as well as equations that represent phase equilibria. More references can be found in the papers quoted in the next section entitled "References on the Thcrmodjmamics of the Liquid-Vapour Equilibrium . 

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