Kinetic Model For Formation Research Articles

J/ψproduction in relativistic heavy ion collisions from a multiphase transport model

Using A Multi-Phase Transport (AMPT) model, we study J/psi production from interactions between charm and anti-charm quarks in initial parton phase and between D and Dbar mesons in final hadron phase of relativistic heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC). Including also the inverse reactions of J/psi absorption by gluons and light mesons, we find that the net number of J/psi from the parton and hadron phases is smaller than that expected from the superposition of initial nucleon-nucleon collisions, contrary to the J/psi enhancement predicted by the kinetic formation model. The production of J/psi is further suppressed if one includes the color screening effect in the parton phase. We have also studied the dependence of J/psi production on the charm quark mass and the effective charm meson mass.

Kinetic Model of Metallocarbohedrene Formation in Arc Plasma Generator

A kinetic model of the formation of stable metal-carbon clusters, which have been designated metallocarbohedrenes, is developed. The metals chosen for the theoretical analysis were titanium and zirconium. An optimum starting composition of composite electrodes was found. The fullerene and Met-Car yields for different metal-to-carbon mass ratios were determined. The maximum yield of Ti8C12 was 0.4% while the maximum yield of Zr8C12 was 0.6%. The theoretical mass spectra of carbon and metallocarbon clusters were explored.

Role of cyclization in the degree-of-polymerization distribution of hyperbranched polymers

A kinetic model of formation of hyperbranched polymers by step polyaddition of a BA f monomer including cyclization was developed. Reactions between acyclic-acyclic and acyclic-cyclic molecules and cyclization within acyclic molecules were considered. For cyclization within isomers of an x-mer, a bridging function between linear and spherical structures was used. Fractions of cyclic x-mers are predicted to increase with increasing degree of polymerization x and overall conversion of B groups. High fractions of cyclics were found in poly[2,2-bis(hydroxymethyl)propanoic acid] (poly (dimethylolpropionic acid)) by mass spectroscopy (ESI/FT MS) in a reasonable agreement with the model.

Disaggregation of Particles with Biospecific Interactions in Shear Flow

The disaggregation of biospecifically interacting particles in shear flow is studied on the basis of kinetic modeling of formation and breakup of ligand–receptor bonds. The reaction rate theory is employed to improve earlier estimations of the critical force required to separate the surfaces. A chain of particles connected through ligand–receptor bonds responds to an external load as a contorted elastic rod. The breakup of the many-particle aggregate is attributed to the rupture of the backbone rod-like chain of particles. The theoretical model is found to be in good agreement with our experimental data on disaggregation of particles of latex immunoconjugates and blood platelets in shear flow.

Kinetic Model for Formation of Aromatics in the High Temperature Chlorination of Methane1

ABSTRACT A detailed thermochemical kinetic model consisting of 165 reversible reactions has been developed to describe catalyzed polymerization of methane under adiabatic conditions. The model, an extension of that previously proposed (Weissman and Benson, 1984, 1989), was tested against available experimental data for CH3C1 pyrolysis in the absence and presence of CH4 in the temperature range 1260-1310 K (Weissman and Benson, 1984). Predictions of major product yields are reasonable although predictive inadequacies are discussed. Product distributions in the CH4/CI2 reaction were studied as a function of inlet/mixing temperature (To = 750-900 K), reactor pressure (PR = 1.0 —5.0 atmospheres) and CH4:C1, mole ratio (1.0-2.0). Product distribution is shown to be a strong function of inlet temperature and reactanl mole ratio. Choice of these parameters define the “window” of accessible reaction conditions experimentally available for useful product formation. Commercially attractive C2 yields (C2 H 2, C2H4),...

Kinetics of Formation of Quasi-Monodisperse Micelles

A new kinetic model of formation of quasi-monodisperse micelles is proposed, preserving the main relaxation features of the polydisperse micellers. Two kinds of co-existing monodisperse micelles are considered: q-micelles and p-micelles. During the fast process some of p-micelles. releasing Δp = p - q monomers, transform into q-micelles (or vice versa). During the slow relaxation process the micelles destroy or form to reach the final equilibrium. Expressions for the relaxation times of these two processes and for the concentrations of the free monomers and the micelles are obtained by means of an asympotic method. The solutions in the inner time domain (fast process) and the outer one (slow process) are matched and thus an uniformly valid solution is found. The quasi-monodisperse model is consistent with the polydisperse one if thc q- and p-micelles have equal equilibrium concentrations and Δp is the width of the miceller size distribution.