Exchange constants

Here iC is the intrinsic anisotropy constant due to the crystalline anisotropy. After the demagnetization in the longest direction, k is the shape-dependent constant (for an infinite cylinder k = 1.38), M is the exchange constant, and R the particle radius. An infinite cylinder with only shape anisotropy gives... 

Under equiUbrium or near-equiUbrium conditions, the distribution of volatile species between gas and water phases can be described in terms of Henry s law. The rate of transfer of a compound across the water-gas phase boundary can be characterized by a mass-transfer coefficient and the activity gradient at the air—water interface. In addition, these substance-specific coefficients depend on the turbulence, interfacial area, and other conditions of the aquatic systems. They may be related to the exchange constant of oxygen as a reference substance for a system-independent parameter reaeration coefficients are often known for individual rivers and lakes. 

The anion-exchanger concentration is shown not to influence strongly the exchange constants. It indicates that there is no either the extractant or compound formed in the organic phase self-association. 

In order to determine the solvation numbers and the exchange constants it is assumed that one (Lys HBr)n residue consists of two parts, namely, the ionic group (numbered 2) and the less polar remainder of the molecule (numbered 1). Plotting... 

The equilibrium constant (exchange constant) for this equilibrium is given by... 

Example SHELL AND TUBE HEAT EXCHANGER DYNAMIC MODEL WITH 8 FINITE DIFFERENCE ELEMENTS CONSTANT HTM=20,HMS=20 HEAT EXCHANGE CONSTANTS... 

Steady-State Heat Exchanger Constant U=1.5 Heat transfer coefficient [kJ/s m2 K] Constant CP=4.18 Specific heat capacity [kJ/kg K] Constant WH=8.5 Mass flow rate of hot fluid [kg/s] Constant WC=4.17 Mass flow rate,cold fluid [kg/s] Constant TCIN = 323 Inlet cold water temp.[K] Constant TCOUT = 343 Outlet cold water temp. [K]... 

The activities fi may be calculated in different ways (e.g., Appelo and Postma, 1993) and, in collecting exchange constants from the literature, care must be taken to note the method used. By the Gaines-Thomas convention, the activity... 

The original ion-exchange treatment was developed for competition between reactive and inert monoanions, but Chaimovich, Quina and their coworkers have extended it to competition between mono and dianions (Cuccovia et al., 1982a Abuin el al., 1983a). The ion-exchange constant for exchange between thiosulfate dianion and bromide monoanion is not dimensionless as in (7) but depends on salt concentration, and the formalism was developed for analysing micellar effects upon reaction of dianionic nucleophiles, e.g. thiosulfate ion. 

The ion-exchange constants, K, in (7) should be related to the individual mass action constants, K land Ky, and this seems to be correct, based on limited evidence and some major approximations (Bunton et al., 1983a). A recent and more detailed data analysis shows that the value of the ion-exchange constant is consistent with values of the individual constants (Rodenas and Vera, 1985). 

CTAC1, CTABr, CTAOH + OH . k /ky, 0.01. Kinetic data analysed using either independent binding or ion exchange constants. IE and M A... 

One can improve upon the TF model by incorporating two-electron effects into P nlpl as the approximate, local Dirac exchange energy functional (cx is the Dirac exchange constant)... 

Addition of 81-SH to 80-SS-81 led to formation of the homodisulfide compounds and an equilibrium, with an exchange constant of 1.8, was established. The presence of the templating (D)Pro(L)Val(D)Val tri-peptide in this mixture, shifted the equilibrium dramatically and the formation of the homodisulfide 80-SS-80 was amplified with a Keq=32. Since the templating tri-peptide was supported on polymer beads, the isolation of receptor 80-SS-80 (in 97% purity) was achieved easily by extraction of the beads. The formation of multiple hydrogen bonds between the template and the components of the DCL, led to the isolation of the best possible receptor available from the building blocks present in the equilibrated mixture. 

The ion exchange method, (28, 80) which consists in determining the ion exchange constants of a complexed and uncomplexed transition metal cation versus a non-complex forming reference cation, leading to the determination of... 

At all but very high temperatures it is necessary to employ the complete equation because the vibrational frequencies for all these molecules are quite high. (Notice at room temperature u(H2) 21, and u(HI) 11). Harmonic oscillator rigid rotor calculated equilibrium constants are shown in Fig. 4.4. As expected the low temperature limiting value, while bounded, is significantly different from unity. At extremely high temperature Equation 4.95 applies and the isotope exchange constant is... 

Henry constant (mmol-L -bar ) acidity constant of the couple (C02-Bicarbonate) composition of gas in A (%) liquid-gas exchange constant (day ) standard deviation of the variable A... 

A pseudophase ion exchange model has been applied to reactions in micellar systems with varying success (1-7). According to this model, the distribution of nucleophile is considered to depend on the ion-exchange equilibrium between the nucleophile and the surfactant counterion at the micelle surface. This leads to a dependence on the ion-exchange constant (K g) as well as on the degree of dissociation (a) of the surfactant counterion. The ion exchange (IE) model has recently been extended to oil in water microemulsions (8). 

The theory of glass membranes with two layers characterized by different ion exchange constants and different mobilities of the exchanged ions was developed by Conti and Eisenman [61]. Assuming a stationary state they obtained (3.4.1) or (3.4.4) expanded by an expression that is a function of the cation concentration at the boundary between the two membrane phases and their mobilities. This term can be considered constant. 

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