Pressure, relationship with activity

ANS I would disagree with your statement that elastance cannot be used to describe both the passive and active relationship between pressure and volume. If it were possible to examine the ventricle at a specific time in systole and measure the mechanical properties, you will find that that elastance has increased from its diastolic value. We could show this using our flow pulse technique where within 30 ms we were able to withdraw 1-2 ml of volume. We typically observe a large decrease in pressure, more so than we would see during diastole. That is, it is a stiffer appearing ventricle. 

In the osmotic pressure method, the activity of the solvent in the dilute solution is restored to that of the pure solvent (i.e., unity) by applying a pressure m on the solution. According to a well-known thermodynamic relationship, the change in activity with pressure is given by... 

Most members of the imidazolylphenylpyridazinone series have been found to produce dose-related increases in myocardial contractility that were associated with minor increases in heart rate and decreases in systemic arterial blood pressure. Studies of structure-activity relationships in this class have been published [25-27]. 

This area is a development in the usage of NDDO models that emphasizes their utility for large-scale problems. Structure-activity relationships (SARs) are widely used in the pharmaceutical industry to understand how the various features of biologically active molecules contribute to their activity. SARs typically take the form of equations, often linear equations, that quantify activity as a function of variables associated with the molecules. The molecular variables could include, for instance, molecular weight, dipole moment, hydrophobic surface area, octanol-water partition coefficient, vapor pressure, various descriptors associated with molecular geometry, etc. For example, Cramer, Famini, and Lowrey (1993) found a strong correlation (r = 0.958) between various computed properties for 44 alkylammonium ions and their ability to act as acetylcholinesterase inhibitors according to the equation... 

The volatility of agent VX is relatively low (vapor pressure 0.0007 mm HG (DA, 1974 MacNaughton and Brewer, 1994). A vapor concentration of 10.5 mg/m has been reported for a temperature of 25°C (DA, 1974) (although not adequately described in the reference, this is presumably the saturation concentration above a pure liquid). Because VX does not absorb UV radiation above 290 mn (Rewick et al., 1986), photodegradation is not a significant environmental fate process. Based on structure-activity relationships, VX is predicted to react in the troposphere with photochemically produced hydroxyl radicals, with a half-hfe estimated to be 0.24 days (Atkinson, 1987). 

In keeping with this method, several approaches have been developed to document methods and dose-response relationships for irritation in humans. This work suggests that, at least for nonreactive compounds such esters, aldehydes, ketones, alcohols, carboxylic acids, aromatic hydrocarbons, and pyridine, the percentage of vapor pressure saturation of a compound is a reasonable predictor of its irritant potency. Specific physical properties of molecules predict overall irritation potential. This work is based on the identification of irritant thresholds for homologous series of specific agents. Quantitative structure-activity relationships derived from such work suggests a reasonable model to explain mucosal irritation. 

Chen N, Yang H, Niu J, Liu S (2013) Determination of kinetic parameters and structure-activity relationships of ginsen-osides as inhibitors of cyclin-dependent kinase 5/p25 using ultra-pressure liquid chromatography with triple quadrupole tandem mass spectrometry. Rapid Commun Mass Spectrom 27 985-992... 

Where and LH are the corresponding activation energy and enthalpy of phase transition and the coefficient defines the maximum probability that molecules will cross the interface between the liquid and SCF (vapor) phases. This simple relationship can explain the behavior of the mass transfer coefficient in Figure 15 when it is dominated by the interfacial resistance. Indeed, increases with temperature T according to Eq. (49) also, both parameters E and A// should decrease with increase of pressure, since the structure and composition of the liquid and vapor phases become very similar to each other around the mixture critical point. The decrease of A/f with pressure for the ethanol-C02 system has been confirmed by interferometric studies of jet mixing described in Section 3.2 and also by calorimetric measurements described by Cordray et al. (68). According to Eq. (43) the diffusion mass transfer coefficient may also increase in parallel with ki as a result of more intensive convection within the diffusion boundary layer. 

For in-situ experiments most commonly used microscopic and spectroscopic techniques are environmental transmission electron microscopy (E-TEM) [207-209], In-situ vibrational spectroscopic [210-212], ambient pressure X-ray photoelectron spectroscopy [206,210,213], X-ray absorption spectroscopy [213,214-217], and Raman spectroscopy [218]. Making use of this in-situ experiments, the solar fuel generation processes will get a new dimension to the state-of-the-art beliefs. Moreover, the catalysts structure, coverage and composition also change with time, the combination of ultrafast of in-situ spectroscopic techniques reveal the structure and catalytic activity relationships (See Table 7) [217]. 

For purposes of developing general equations for the thermodynamic properties of electrolyte solutions, it is useful to recalculate experimental values to a single reference pressure. This allows experimental data for different solution properties (e.g., activities, enthalpies, and heat capacities) whose relationships with each other are defined on an isobaric basis, to be considered in the overall regression... 

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