The kinetics of a diffusing particle near a reversible trap may be described by an extension of the Feynman-Kac equation to the case of reversible binding, which can occur within a finite reaction sphere. We obtain the Green's function solution for the Laplace transform of this equation when the particle is initially either bound or unbound. We study the solution in the time-domain by either in...

The problem of wave-front propagation for the n-dimensional reaction-diffusion system involving Kolmogorov-Petrovskii-Piskunov kinetics and the diffusion transport with a finite velocity has been considered. By using a scaling procedure we have given an asymptotic derivation of the equation governing the evolution of a reaction front in the long-time large-distance limit. It has been found that...

In the present work, the usefulness of dried activated sludge has been investigated for the removal of copper ions from aqueous solutions. Kinetic data and equilibrium sorption isotherms were measured in batch conditions. The influence of initial pH, metal concentration and copper salt nature on the metal removal kinetics has been studied. Copper uptake was time contact, initial copper concentr...

In this paper, we report our numerical simulation on the electronic-optical properties of the phosphorescent organic light emitting diodes (PHOLEDs) devices. In order to calculate the electrical and optical characteristics such as the transport behavior of carriers, recombination kinetics, and emission property, we undertake the finite element method (FEM). Our model includes Poisson’s equation...

A master equation approach is developed to find the rate-limiting steps in biopolymer folding, where the folding kinetics is described as a linear combination of basic kinetic modes determined from the eigenvalues and eigenvectors of the rate matrix. Because the passage of a rate-limiting step is intrinsically related to the folding speed, it is possible to probe and to identify the rate-limiti...

The use of ultrasound to enhance the transport phenomena in food processes has been well recognised in recent times. The objective of this study was to evaluate the effect of sonication on hydration rate and pasting profile of navy beans. The hydration kinetics for control and ultrasound assisted soaking was mathematically described using mechanistic (Fickian diffusion) and empirical (Peleg's e...

The aim of the present work was to investigate the ability of Cocopeat to remove of lead (II) from aqueous solutions. The effects of different parameters such as particle size, adsorbent dosage, pH, contact time, agitation speed and concentration on the removal process has been investigated. The maximum removal of lead ion (92.5%) took place in the pH range of 4 contact time in 30 minutes a...

The nonlinear dynamical system modeling the immobilized enzyme kinetics with Michaelis-Menten mechanism for an irreversible reaction without external mass transfer resistance is considered. Laplace transform homotopy perturbation method is used to obtain the approximate solution of the governing nonlinear differential equation, which consists in determining the series solution convergent to the...

The controlling kinetics of the water solubility of two synthesized mono azo naphthalimide based disperse dyestuffs in the presence of two different dispersing agents namely Irgasol DAM and lyoprint EV agents at various temperatures were investigated. An exponential rate equation was found to describe the dissolution process. The addition of Irgasol DAM and Lyoprint EV dispersing agents increas...

A moving, solidifying interface that grows by the instantaneous adsorption of a diffusing solute is described by the classic one-sided “Stefan problem” [15, 19]. More generally, the behavior of precipitate growth can depend on both surface kinetics and bulk drift of the depositing species. We generalize the Stefan problem and its interface boundary condition to explicitly account for both surfa...