Kinetic activity factor

The charge of the critical complex AB naturally is equal to the algebraic sum of the charges of A and B. If, for example, A is a univalent ion and B is a neutral molecule, the critical complex will have a valence of 1. The kinetic activity factor therefore will be independent of the electrolyte content between rather wide limits since /a and fx will vary approximately in the same manner. At larger ionic strengths a more distinct salt effect will be observed since individual differences between A and AB will enter and because /b will no longer be equal to unity. 

In the equation for the electrode reaction rate expressed through overpotential [see Section 3.1, Eq. (61a)], a kinetic activity factor is present ... 

The so-called kinetic activity factor, determined by the activity coefficients of the components and activated complex, was discussed in Section 2.3. 

In the PPF, the first factor Pi describes the statistical average of non-correlated spin fiip events over entire lattice points, and the second factor P2 is the conventional thermal activation factor. Hence, the product of P and P2 corresponds to the Boltzmann factor in the free energy and gives the probability that on<= of the paths specified by a set of path variables occurs. The third factor P3 characterizes the PPM. One may see the similarity with the configurational entropy term of the CVM (see eq.(5)), which gives the multiplicity, i.e. the number of equivalent states. In a similar sense, P can be viewed as the number of equivalent paths, i.e. the degrees of freedom of the microscopic evolution from one state to another. As was pointed out in the Introduction section, mathematical representation of P3 depends on the mechanism of elementary kinetics. It is noted that eqs.(8)-(10) are valid only for a spin kinetics. 

Lie WJ, Homburg CH, Kuijpers TW, Knol EF, Mul FR Roos D, Tool AT Regulation and kinetics of platelet-activating factor and leukotriene C4 synthesis by activated human basophils. Clin Exp Allergy 2003 33 1125-1134. 

McGee M. P., Li L. C. Functional difference between intrinsic and extrinsic coagulation pathways. Kinetics of factor X activation on human monocytes and alveolar macrophages. J Biol Chem 1991 266,8079-85. 

Attempts to polymerise isobutene by free radical catalysis have all failed [16,17] and copolymerisation experiments show that the t-butyl radical has no tendency to add to isobutene. The reasons for these facts are not at all obvious. Evidently, they cannot be thermodynamic and therefore they must be kinetic. One factor is probably that the steric resistance to the formation of polymer brings with it a high activation energy [17], and that the abstraction by a radical of a hydrogen atom from isobutene, to give the methallyl radical, has a much smaller activation energy. This reaction will also be accelerated statistically by the presence of six equivalent hydrogen atoms. 

The transfer of chemical molecules from oil to water is most often a surface area phenomenon caused by kinetic activity of the molecules. At the interface between the liquids (either static or moving), oil molecules (i.e., benzene, hexane, etc.) have a tendency to disperse from a high concentration (100% oil) to a low concentration (100% water) according to the functions of solubihty, molecular size, molecular shape, ionic properties, and several other related factors. The rate of dispersion across this interface boundary is controlled largely by temperature and contact surface area. If the two fluids are static (i.e., no flow), an equilibrium concentration will develop between them and further dispersion across the interface will not occur. This situation is fairly common in the unsaturated zone. 

Enolization and ketonization kinetics and equilibrium constants have been reported for phenylacetylpyridines (85a), and their enol tautomers (85b), together with estimates of the stability of a third type of tautomer, the zwitterion (85c). The latter provides a nitrogen protonation route for the keto-enol tautomerization. The two alternative acid-catalysed routes for enolization, i.e. O- versus Af-protonation, are assessed in terms of pK differences, and of equilibrium proton-activating factors which measure the C-H acidifying effects of the binding of a proton catalyst at oxygen or at nitrogen. 

Selected entries from Methods in Enzymology [vol, page(s)] Sulfonylation reaction, 11, 706 reaction kinetics, 11, 707 second-order rate constants for inactivation of chymotrypsin, trypsin, and acetylcholine esterase by PMSE and related sulfonylat-ing agents, 11, 707 reactivation of PMS-chymotrypsin, 11, 710 as inhibitor [of calcium-activated factor, 80, 674 of cathepsin G, 80, 565 of crayfish trypsin, 80, 639 of elastase, 80, 587 of pro-lylcarboxypeptidase, 80, 465 of protease Re, 80, 691 of protease So, 80, 695 of protein C, 80, 329] proteolysis, 76, 7. 

MICHAELIS-MENTEN KINETICS PREEXPONENTIAL FACTOR ARRHENIUS EQUATION COLLISION THEORY TRANSITION-STATE THEORY ENTROPY OF ACTIVATION PRENYL-PROTEIN-SPECIFIC ENDOPEP-TIDASE... 

Table 3. Temperature range in °C, kinetics, activation energy in kcal/mole and preexponential factor k0 in s l for the first order, in torr/sfor the zero order reaction...

KLC >R0GGE E MOMMERSTEG M, AKKmMAN JWN. Kinetics of platelet-activating factor l-O-alkyl-2-aoetyl-sa-glycerol-3-phosphocholine-induced fibrinogen binding to human platelets. JBiol Chem 261 11071-11076,1986. 

Mills P C, Ng J C, Seawright A A et al 1995 Kinetics, dose response, tachyphylaxis and cross-tachyphylaxis of vascular leakage induced by endotoxin, zymosan-activated plasma and platelet-activating factor in the horse. Journal of Veterinary Pharmacology and Therapeutics 18 204-209... 

The intersection of the reactant and product surfaces (point S) represents the transition state (or activated complex ), and is characterized by a loss of one degree of freedom relative to the reactants or products. The actual electron-transfer event occurs when the reactants reach the transition-state geometry. For bimolecular reactions, the reactants must diffuse through the solvent, collide, and form a precursor complex prior to electron transfer. Hence, disentangling the effects of precursor complex formation from the observed reaction rate can pose a serious challenge to the experimentalist unless this is done, the factors that determine the kinetic activation barrier for the electron-transfer step cannot be identified with certainty. 

There are at least two factors that are likely to contribute to this difference in the intrinsic rate constants for the two pathways. One is that in the ki k-i pathway the nucleophile is a strongly basic alkoxide ion. The strong solvation of such oxyanions is known to reduce their kinetic activity. This reduction is a classic... 

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