Physicochemical modeling

Figure 5.3-19. Deterministic models based on physicochemical models according to the type... 

D., Smith, 1. R., Sore, N. E., Wilks, T.. Development of a new physicochemical model for brain penetration and its application to the design of centrally acting H2 receptor histamine antagonists. J. Med. Chem. 1988, 31, 656-671. 

JB Dressman, D Fleisher, GL Amidon. Physicochemical model for dose-dependent drug absorption. J Pharm Sci 73 1274-1279, 1984. 

The models which we have developed can be classified as follows. Some are intended to represent physicochemical processes and properties by mimicking quantitatively concepts which have become accepted by chemists in general. A simple example would be the transfer of electronic charge between two atoms of differing electronegativities. Other models are statistical in nature. We have applied parameters quantified by the physicochemical models to series of chemical data. The relationships thus derived by various statistical techniques, and their form, is such that they are readily applicable to the task of quantifying the evaluation process in EROS. Further discussion of these points is a major feature of this article. 

The next two sections deal with physicochemical models for the thermochemical and electronic effects which are used in the evaluations. This work is fairly well progressed. However, there are other effects which we are fully aware influence reactivity appreciably, but which we have so far investigated to only a limited degree. These include solvent and steric effects. We refer to these topics only briefly later in this article. 

A kinetic model based on the Flory principle is referred to as the ideal model. Up to now this model by virtue of its simplicity, has been widely used to treat experimental data and to carry out engineering calculations when designing advanced polymer materials. However, strong experimental evidence for the violation of the Flory principle is currently available from the study of a number of processes of the synthesis and chemical modification of polymers. Possible reasons for such a violation may be connected with either chemical or physical factors. The first has been scrutinized both theoretically and experimentally, but this is not the case for the second among which are thermodynamic and diffusion factors. In this review we by no means pretend to cover all theoretical works in which these factors have been taken into account at the stage of formulating physicochemical models of the process... 

The solution of the problems of the first kind implies an in depth consideration of the formation of a multiblock copolymer macromolecule at the interphase boundary. This process may be described in the framework of the above-discussed physicochemical model as follows. 

Several different physicochemical models have been proposed to predict and explain the retention behavior in liquid-solid chromatography. The models can be divided into two groups depending on the assumptions made concerning the fundamental mechanism of the chromatographic process. The two assumptions are as follows ... 

The combined score from the fingerprint and physicochemical models was the best to confirm a logical trend from lead optimization to launched drugs. Indeed, as shown in Figure 13.4, the best scored compounds were checked for the phase in which they belonged and the average scores suggested that, as a trend, compounds predicted as promiscuous are found more often in the lead optimization phase than... 

Physicochemical Model. In constructing the GDF model, it is assumed that gasification at the solid regressing surface is driven by conductive heat feedback from a two-stage flame occurring in the gas phase (see Figure 1). This solid-to-gas phase step is generally endo-... 

Whatever the detailed physicochemical model of the interface, most models of the air-water exchange flux are written as the product of two factors, one describing the physics, the other the chemistry. What are these factors ... 

I. K. Karpov, Physicochemical Modeling by Computer in Geochemistry, Nauka, Sib. Otd., Novosibirsk, USSR, 1981. 

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