Jump rate constant

The jump rate constants reported in our previous work [88] were calculated using Eq. (20). Within the harmonic approximation, the difference in... 

Another direct effect is that high penetrant concentrations can increase polymer chain mobility (plasticization), thereby increasing the diffusion coefficient [1], An indirect effect concerns relative sorption among different sorption states. From microscopic reversibility [22], the ratio of equilibrium solubilities within different sorption states equals the ratio of jump rate constants between them. 

Next it is necessary to assign relative sorption probabilities and jump rate constants to the jump network. The distributions of solubility coefficients [calculated by Eq. (48)] and rate constants are required. First, a cumulative solubility coefficient distribution is calculated equals the prob-... 

The final step in obtaining a diffusion coefficient is to simulate the dynamics of a penetrant molecule on the network of sorption states and rate constants. Analogous to the frozen positions of voids and channels in a glassy polymer, the relative sorption probabilities and jump rate constants typically remain constant throughout the diffusion simulation. For uniform rate constants on an ordered lattice, it is possible to solve the dynamics analytically. For the disordered network found for voids through a polymer matrix, a numerical solution is required. 

The amount of time that elapses between penetrant jumps thus depends explicitly on the instantaneous sorption state population and on the distribution of jump rate constants out of occupied states. 

With M = He, experimeuts were carried out between 255 K aud 273 K with a few millibar NO2 at total pressures between 300 mbar aud 200 bar. Temperature jumps on the order of 1 K were effected by pulsed irradiation (< 1 pS) with a CO2 laser at 9.2- 9.6pm aud with SiF or perfluorocyclobutaue as primary IR absorbers (< 1 mbar). Under these conditions, the dissociation of N2O4 occurs within the irradiated volume on a time scale of a few hundred microseconds. NO2 aud N2O4 were monitored simultaneously by recording the time-dependent UV absorption signal at 420 run aud 253 run, respectively. The recombination rate constant can be obtained from the effective first-order relaxation time, A derivation analogous to (equation (B2.5.9). equation (B2.5.10). equation (B2.5.11) and equation (B2.5.12)) yield... 

The equilibrium binding constant for this 1 1 association is Xu = ki/lLi. The Xu values were measured spectrophotometrically, and the rate constants were determined by the T-jump method (independently of the X,j values), except for substrate No. 6, which could be studied by a conventional mixing technique. Perhaps the most striking feature of these data is the great variability of the rate constants with structure compared with the relative insensitivity of the equilibrium constants. This can be accounted for if the substrate must undergo desolvation before it enters the ligand cavity and then is largely resolvated in the final inclusion complex. ... 

K = 63 M 1, Kb = 1.4M-1)47 lithium-7 (K = 14 M 1 K" = 0.5 M 1) 49) and for cesium-133 (K, st 50 M-1, K = 4M 1)S0). In the case of sodium-23, transverse relaxation times could also be utilized to determine off-rate constants k ff = 3 x 105/sec k"ff = 2x 107/sec47,51). Therefore for sodium ion four of the five rate constants have been independently determined. What has not been obtained for sodium ion is the rate constant for the central barrier, kcb. By means of dielectric relaxation studies a rate constant considered to be for passage over the central barrier, i.e. for jumping between sites, has been determined for Tl+ to be approximately 4 x 106/sec 52). If we make the assumption that the binding process functions as a normalization of free energies, recognize that the contribution of the lipid to the central barrier is independent of the ion and note that the channel is quite uniform, then it is reasonable to utilize the value of 4x 106/sec for the sodium ion. 

The entries were reconstructed for Eq. (3-30) from the rate constant values of kI = 0.406 s l and k 1 = 383 L mol"1 1 from Ref. 2. One calculation is for the reaction starting with A alone, and the other for a concentration-jump experiment with a two-fold dilution of a solution made up to have an original concentration of A of 2.84 X... 

Competition reactions ad eosdem, 106 ad eundem, 105 (See also Reactions, trapping) Competitive inhibitor, 92 Complexation equilibria, 145-148 Composite rate constants, 161-164 Concentration-jump method, 52-55 Concurrent reactions, 58-64 Consecutive reactions, 70, 130 Continuous-flow method, 254—255 Control factor, 85 Crossover experiment, 112... 

The most significant results obtained for complexes of iron(II) are collected in Table 3. The data derive from laser Raman temperature-jump measurements, ultrasonic relaxation, and the application of the photoperturbation technique. Where the results of two or three methods are available, a gratifying agreement is found. The rate constants span the narrow range between 4 x 10 and 2 X 10 s which shows that the spin-state interconversion process for iron(II) complexes is less rapid than for complexes of iron(III) and cobalt(II). 

Relaxation Experiments (Jump Changes of Concentration of Oxygen, Temperature and Humidity) and Rate Constants of Respective Elementary Reaction Steps 482... 

RELAXATION EXPERIMENTS (JUMP CHANGES OF CONCENTRATION OF OXYGEN, TEMPERATURE AND HUMIDITY) AND RATE CONSTANTS OF RESPECTIVE ELEMENTARY REACTION STEPS... 

The difference between the chemiluminescence response of polyisoprene and cellulose on jump changes of atmosphere from nitrogen to oxygen (cf. Figure 16 and Figure 17) is probably due to the fact that the rate constant /y < 4 for... 

Reactions of eh with H and OH were once considered diffusion-controlled see, however, Elliot et al. (1990). The rate constants, 2.5—3.0 x 1010 M-1s 1 (see Table 6.6), are high. In both cases, a vacancy exists in the partially filled orbitals of the reactants into which the electron can jump. Thus, hydrogen formation by the reaction eh + H may be visualized in two steps (Hart and Anbar, 1970) eh + H—H, followed by H + H20— OH" This reaction has no isotope effect, which is consistent with the proposed mechanism. The rate of reaction with OH is obtained from the eh decay curve at pH 10.5 in the absence of dissolved hydrogen or oxygen, where computer analysis is required to take into account some residual reactions. At higher pH (>13), OH exists as O- and the rate of eh + O—"02 has been measured as 2.2 x 1010 M-1s-1. 

Stress-Jump Experiments. The results of stress-jump experiments for HM-HEC monolayers with various compositions are shown in Table II, where the relaxation rate constants, ctRT, were calcu-... 

Their q-values, either calculated from the experimental conditions or chosen for best fit, and their corresponding relaxation rate constants, obtained from separate stress-jump experiments, are listed in Table III. 

Table 2 Rate constants for the binding of ethidium bromide to DNA assuming the mechanism shown in Scheme 2 determined in temperature jump (TJ) or stopped flow (SF) experiments...

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