Internal particle behavior

A few reactor models have recently been proposed (30-31) for prediction of integral trickle-bed reactor performance when the gaseous reactant is limiting. Common features or assumptions include i) gas-to-liquid and liquid-to-solid external mass transfer resistances are present, ii) internal particle diffusion resistance is present, iii) catalyst particles are completely externally and internally wetted, iv) gas solubility can be described by Henry s law, v) isothermal operation, vi) the axial-dispersion model can be used to describe deviations from plug-flow, and vii) the intrinsic reaction kinetics exhibit first-order behavior. A few others have used similar assumptions except were developed for nonlinear kinetics (27—28). Only in a couple of instances (7,13, 29) was incomplete external catalyst wetting accounted for. 

Carboxy- and amino-functionaUzed polystyrene nanoparticles have been synthesized by the miniemulsion process using styrene and the functional monomers acrylic acid (AA) or 2-aminoethyl methacrylate hydrochloride (AEMH) as functional comonomers [30,31]. By changing the amount of the comonomer, different surface densities of the charged groups could be realized. Since a fluorescent dye was incorporated inside the nanoparticles, the uptake behavior of different cell Unes could be determined as a function of the surface functionalization [30,31]. It was found that, in general, the uptake of the nanoparticles into the cells increases with increasing functionality on the particle s surface. For HeLa cells, for example, the internalized particle amount was up to sixfold better for carboxy-functionaUzed polystyrene (PS) nanoparticles than for non-functionalized PS particles. For amino functionalized PS nanoparticles, an up to 50-fold enhanced uptake could be detected. In order to investigate the actual uptake pathway into HeLa cells, positively... 

GASFLOW models geometrically complex containments, buildings, and ventilation systems with multiple compartments and internal structures. It calculates gas and aerosol behavior of low-speed buoyancy driven flows, diffusion-dominated flows, and turbulent flows dunng deflagrations. It models condensation in the bulk fluid regions heat transfer to wall and internal stmetures by convection, radiation, and condensation chemical kinetics of combustion of hydrogen or hydrocarbon.s fluid turbulence and the transport, deposition, and entrainment of discrete particles. 

Liang, J. C., Chiu, M. H. (2003). Using dynamic representations to diagnose students conceptions of the behavior of gas particles. Paper presented at the International Conferenee on Seienee Mathematies Learning, Taipei, Taiwan, R.O.C. 

Atoms are the fundamental building blocks of chemistry, but are atoms made of other, still smaller particles It turns out that atoms do have internal structures. Furthermore, the internal structure of atoms of one particular element differs from that of every other element. These differences in structure are what make the chemishy of one element different from that of any other. The rich diversity of chemical behavior results from the different internal structures of atoms of different elements. 

To construct a model which will give behavior similar to another bed, for example, a commercial bed, all of the dimensionless parameters listed in Eqs. (37) or (39) must have the same value for the two beds. The requirements of similar bed geometry is met by use of geometrically similar beds the ratio of all linear bed dimensions to a reference dimension such as the bed diameter must be the same for the model and the commercial bed. This includes the dimensions of the bed internals. The dimensions of elements external to the bed such as the particle return loop do not have to be matched as long as the return loop is designed to provide the proper external solids flow rate and size distribution and solid or gas flow fluctuations in the return loop do not influence the riser behavior (Rhodes and Laussman, 1992). 

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