Diffusion influence

Szabo A, Shoup D, Northrup S H and McCammon J A 1982 Stochastically gated diffusion-influenced reactions J. Chem. Phys. 77 4484-93... 

Most descriptions of the dynamics of molecular or particle motion in solution require a knowledge of the frictional properties of the system. This is especially true for polymer solutions, colloidal suspensions, molecular transport processes, and biomolecular conformational changes. Particle friction also plays an important role in the calculation of diffusion-influenced reaction rates, which will be discussed later. Solvent multiparticle collision dynamics, in conjunction with molecular dynamics of solute particles, provides a means to study such systems. In this section we show how the frictional properties and hydrodynamic interactions among solute or colloidal particles can be studied using hybrid MPC-MD schemes. 

K. Tucci and R. Kapral, Mesoscopic model for diffusion-influenced reaction dynamics, J. Chem. Phys. 120, 8262 (2004). 

Explain how each factor in Fick s law of diffusion influences gas exchange... 

Here we give a brief account of some unimolecular processes other than isomerization. No detailed description of bimolecular processes will be offered, except to remark that (1) the knowledge gained from the unimolecular processes is often useful in interpreting the bimolecular processes and (2) in some cases, the bimolecular processes resemble normal diffusion-influenced reactions in the condensed phase. 

The analysis of gas absorption proceeding exponentially under experimental conditions provides the gas solubility [C ] and the value of kL a. As a rule of thumb, this value should be approximately ten-fold larger than the rate of a subsequent chemical reaction in order to eliminate diffusion influences on the latter reaction [41]. 

For those readers requiring further information on the factors effecting the kinetic versus diffusion control of the SSP process, this has been reported by several authors (for example, kinetic aspects [4, 8, 20] and diffusion-influenced aspects [5-7, 9, 11-13, 15]). 

The relatively simple spectral and kinetic behavior of 10-CPT in methanol-water mixtures can be described by a well-developed reversible diffusion influenced two-step model (Scheme 1). We successfully applied this scheme in the experimental and theoretical studies of reversible ESPT processes in solution. 

Dr. Kapo How does diffusion influence the kinetics of solution ... 

Petersen, E. E. Chem. Eng. Sci. 20 (1965) 587. A general criterion for diffusion influenced chemical reactions in porous solids. 

The picture is different for the bulkier tert-butyl alcohol the kinetics of its adsorption at room temperature are markedly retarded with increasing crystallite sizes of HZSM-5 and they exhibit a t12 dependence (t is the time after adsorption) (see Fig. 3c of ref. 8d). This is symptomatic of a diffusion-influenced process. 

Right Profiles of decrease in F(t)/F(0) for intraparticle diffusion-influenced zero-order reaction with spherical immobilized enzyme particles packed in the reactor operated under a constant conversion policy (x = 0.99). Enzyme activity decays as E(t)/E(0) = exp ( kd t). 

At s = 0 the concentration corrections in Eq. (3.667) become the rates of excitation quenching by any partner that does not belong to a given couple (reactant pair). These bachelors compete for an excitation with the reactants in a couple when they move apart for a while between successive recontacts. Similar results were obtained with the many-particle theory of diffusion-influenced reactions based on the revised superposition approximation and became known as MPK1 [51]. The authors were the first who managed to obtain concentration corrections to the IET result for the kinetics of reversible energy transfer. In a subsequent modification of their theory, named MPK3 [126], the same authors reached the full correspondence with MET. 

Berg s work [120] was chronologically the first theory of a diffusion-influenced reversible reaction that was later on reproduced and analyzed by Agmon and... 

The coupling of kinetics with intra- and extraparticle transport has been the traditional focus of chemical reaction engineering major accomplishments have been admirably summarized by Aris [10]. The effectiveness factor and Thiele parameter of diffusion-influenced catalyst particles represent a balance between their reactive and diffusive properties. In this section, we shall concentrate on the latter. 

This chapter presents generalized and approximate formulae, which enable calculation of the conversion in solid catalyst materials in cases where both reaction and diffusion influence the overall conversion rate. The conversion mainly depends on the following three aspects ... 

Liou, J. S., Balakotaiah, V., and Luss, D., Dispersion and diffusion influences on yield in complex reaction networks. AIChE J. 35, 1509 (1989). 

Bujan-Nunez MC, Lopez-Quintela MA. (2004) Enhancement of the recollision rate in diffusion-influenced reactions in an inhomogeneous medium. J Chem Phys 121 886-889. 

Northrup SH, Allison SA, McCammon JA. Brownian dynamics simulation of diffusion-influenced biomolecular reactions. J. Chem. Phys. 1984 80 1517-1524. 

A. Szabo, J. A. McCammon, S. H. Northrup and D. Shoup, Stochastically gated diffusion influenced reactions, J. Chem. Phys., 77 (1982) 4484-4493. 

S. A. Allison, J. A. McCammon and J. J. Sines, Brownian dynamics of diffusion influenced reactions - inclusion of intrinsic reactivity and gating, J. Phys. Chem., 94 (1990) 7133-7136. 

Reactions that are strongly diffusion influenced benefit from intraparticle convection. This is because the supply of primary reagents can now be driven by bulk diffusion. Furthermore, reversible reactions of the type A + B 5= C + D will show an additional benefit because the reaction products will be swept from the pzulicle interior by convection, when otherwise their greater accumulation would reverse (and therefore hinder) the local rate of reaction. 

Fredrickson3 has formulated expressions for the concentration depolarization of fluorescence in the presence of molecular rotation. A theoretical examination of diffusion influenced fluorescence quenching by nearest possible quenching neighbours in liquids has been made35. A modified version of Smoluchowski - Collins - Kimball formulation of the Stern - Volmer equations has been matched with experimental data for quenching of anthraquinone derivatives by N,N-dimethyl- -toluidine. Another paper discusses this work on the basis of the kinetics of partly diffusion controlled reactions3 . 

Northrup, S. H., S. A. Allison and J. A. McCammon. (1984). Brownian dynamics simulations of diffusion influenced bimolecular reactions. J Chem. Phys. 80 1517. 

In general a is not equal to a due to back diffusion, caused by non-zero pressure at the permeate side, or to contributions of non-separative mechanisms to the total flow and concentration polarisation on feed or the permeate side. Also the presence of surface diffusion influences the ideal separation factor. 

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