Diffusion, generally

Zeohte ciyst lite diffusivities for sorbed gases range from 10" to lO" " cmVs. These diffusivities generally show a strong increase with the adsorbate concentration that is accounted for by the Darken thermodynamic correction factor... 

The addition of defoamers can restore some of this lost strength, but only to a certain point. The defoaming mechanism usually relies upon diffusion of gas bubbles together in the liquid adhesive to form larger bubbles, which, in turn, rise to the surface and break. Diffusion generally decreases with increasing viscosity and stops when the gel point is reached, i.e., when the viscosity approaches infinity, accordingly ... 

The Mallard-Le Chatelier development for the laminar flame speed permits one to determine the general trends with pressure and temperature. When an overall rate expression is used to approximate real hydrocarbon oxidation kinetics experimental results, the activation energy of the overall process is found to be quite high—of the order of 160kJ/mol. Thus, the exponential in the flame speed equation is quite sensitive to variations in the flame temperature. This sensitivity is the dominant temperature effect on flame speed. There is also, of course, an effect of temperature on the diffusivity generally, the dif-fusivity is considered to vary with the temperature to the 1.75 power. 

The effects of broth viscosity on k a in aerated stirred tanks and bubble columns is apparent from Equations 7.37 and 7.41, respectively. These equations can be applied to ordinary non-Newtonian liquids with the use of apparent viscosity as defined by Equation 2.6. Although liquid-phase diffusivity generally decreases with increasing viscosity, it should be noted that at equal temperatures, the gas diffusivities in aqueous polymer solutions are almost equal to those in water. 

O Burnt, pungent, diamine O Pungent, penetrating and diffusive, generally described as nauseating, but in extreme dilution, warm, "burnt", smoky, of very poor tenacity... 

When the catalyst is a porous solid, most of the surface area of the catalyst is the surface area of the inner surface of the pores. Therefore, most of the reaction proceeds in the pore. Gas molecules are transferred to the outer surface of the catalyst by diffusion. Generally speaking, the diffusion is faster than the diffusion inside the pores. Gas molecules collide with the inner wall of the pore before they collide with another molecule for the porous catalyst having an average pore radius rp of a few nm. Such diffusion is called Knudsen diffusion and its diffusion constant D is given by ... 

The diffusion of the sulfur molecules in the pores of the catalyst would be assumed to be mainly influenced by molecular diffusion. This type of diffusion generally occurs in the liquid phase. Since the same liquid was used in both the cases, the coefficient of diffusion would be assumed to be the same. 

After making these adjustments for diffusion in sediments, the mass balance and vertical concentration patterns of nonconservative solutes in saturated sediments can be described by the following one-dimensional advective-diffusive general diagenetic equation (GDE) (Berner, 1980 Aller, 2001 Jprgensen and Boudreau, 2001) ... 

The mass balance and vertical concentration patterns of nonconservative solutes in saturated sediments can be described by the one-dimensional advective-diffusive general diagenetic equation (GDE). 

The latter form is the basic equation of diffusion generally identified as Fick s first law, formulated in 1855 [13]. Fick s first law, of course, can be deduced from the postulates of irreversible thermodynamics (Section 3.2), in which fluxes are linearly related to gradients. It is historically an experimental law, justified by countless laboratory measurements. The convergence of all these approaches to the same basic law gives us confidence in the correctness of that law. However, the approach used here gives us something more. 

Finite diffusion — Finite (sometimes also called -> limited) diffusion situation arises when the -> diffusion layer, which otherwise might be expanded infinitely at long-term electrolysis, is restricted to a given distance, e.g., in the case of extensive stirring (- rotating disc electrode). It is the case at a thin film, in a thin layer cell, and a thin cell sandwiched with an anode and a cathode. Finite diffusion causes a decrease of the current to zero at long times in the - Cottrell plot (-> Cottrell equation, and - chronoamperometry) or for voltammetric waves (see also - electrochemical impedance spectroscopy). Finite diffusion generally occurs at -> hydrodynamic electrodes. 

Elderly patients and people with chronic renal insufficiency are most susceptible to the neurotoxic effects of aciclovir confusion, hallucinations, dizziness, irritabihty, ataxia, tremor, myoclonus, and seizures. The symptoms usually occur within 3 days of the start of therapy and resolve within 5 days after withdrawal. Plasma aciclovir concentrations do not correlate with symptoms. Lumbar puncture and CT scans of the head are essentially unremarkable. The most common electroencephalographic abnormality is diffuse generalized slowing of brain wave activity. 

Correlation factors for vacancy diffusion generally take values of between 0.5 and 0.8. 

The techniques used for restricted and steady-state diffusion generally involve the use of a diaphragm cell. This method has the disadvantage that the cell has first to be calibrated with a system with a known diffusion coefficient, and for systems with relatively slow diffusivities each run may require an inconveniently long time. 

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