Interference internal diffusivities

The interfacial pd selectivity coefficient, the factor multiplying a is determined by the ratio K /K, by the activity coefficient ratio, and by the mobility ratio, when the internal diffusion potential contribution is added. Clearly interferences should correlate with the ratio K /1C, which can be determined from salt extraction coefficients K KX/K K for a series of positive drugs, using common anion salts. This result is well documented in the literature (7,8). A curious correlation for N-based drugs studied by us and by Freiser ( ) is a trend in selectivity... 

Measurements by interference microscopy are, under favorable conditions, capable of yielding both internal diffusivities and apparent diffusivities based on overall sorption rates. The former tend to approach the values obtained from microscopic measurements while the latter yield values similar to those obtained by other macroscopic methods. Of necessity these studies have been carried out in large zeolite crystals. One may expect that smaller crystals may be less defective, although the influence of surface resistance may be expected to be greater. The extent to which these conclusions are applicable to the small zeolite crystals generally used in commercial zeolite catalysts and adsorbents remains an open question. 

Fig. 17 Transient concentration profiles in y-direction (i.e., along 8-ring channels) measured by interference microscopy for a adsorption and b desorption of methanol in a large crystal of ferrierite for pressure steps 5 -> 10 and 10 5 mbar. The form of the profiles shows that both surface resistance and internal diffusion (along the 8-ring chan-...

Logarithmic Reaction Kinetics Logarithmic reaction kinetics are most often associated with low-temperature service tests, the initial stages of oxidation of certain materials, and with thick scale behavior where internal scale cavities or precipitates interfere with diffusion mechanisms [3]. The rate equation describing logarithmic reaction kinetics (Fig. 3) is... 

The Liesegang phenomenon [521], which is a striking nonequilibrimn effect (not only) in laboratory chemistry, describes the formation of periodic precipitation bands of internal reaction products the effect can involve periodicity in time and space and depends on the interference of diffusion, supersaturation, nucleation and growth. The collapse and reformation of supersatnration is of importance, in the sense of an overshoot of a partial process. 

Gas-sensing electrodes differ from ion-selective electrodes in that no species in solution can interfere with the electrode response as only gases can diffuse through the membrane. However, it should be noted that any gas which causes a pH change in the internal electrolyte solution will affect electrode response. 

As a consequence of the collective motion of the neutral system across the homogeneous magnetic field, a motional Stark term with a constant electric field arises. This Stark term inherently couples the center of mass and internal degrees of freedom and hence any change of the internal dynamics leaves its fingerprints on the dynamics of the center of mass. In particular the transition from regularity to chaos in the classical dynamics of the internal motion is accompanied in the center of mass motion by a transition from bounded oscillations to an unbounded diffusional motion. Since these observations are based on classical dynamics, it is a priori not clear whether the observed classical diffusion will survive quantization. From both the theoretical as well as experimental point of view a challenging question is therefore whether quantum interference effects will lead to a suppression of the diffusional motion, i.e. to quantum localization, or not. 

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