Transport flow coupling

In mammalian systems, some examples of solute transport coupled to either H+ or Na+ flow are known (Jessen et al., 1989), yet most Na+-dependent systems do not appear to substitute H+ for Na+. Until characteristic consensus sequences for Na+ and H+ binding are known, the difference between highly specific Na+ coupling and preferential Na+ coupling remain unclear. 

FORTRAN computer program that predicts the species, temperature, and velocity profiles in two-dimensional (planar or axisymmetric) channels. The model uses the boundary layer approximations for the fluid flow equations, coupled to gas-phase and surface species continuity equations. The program runs in conjunction with CHEMKIN preprocessors (CHEMKIN, SURFACE CHEMKIN, and TRAN-FIT) for the gas-phase and surface chemical reaction mechanisms and transport properties. The finite difference representation of the defining equations forms a set of differential algebraic equations which are solved using the computer program DASSL (dassal.f, L. R. Petzold, Sandia National Laboratories Report, SAND 82-8637, 1982). 

Bidoglio, G. (1994) Coupled Processes in Reaction-Flow Transport of Contaminants. In Chemistry of Aquatic Systems Local and Global Perspectives, G. Bidoglio and W. Stumm, Eds., Kluwer Academic, Dordrecht. 

In membrane separation processes, there is convective flow of the feed solution or suspension from the bulk toward the surface of the membrane, where separation and simultaneous slow diffusion of the rejected particles into the bulk occur because of a concentration difference. This slow back transport, coupled with... 

The flow of electrons through the election transport complexes is coupled to the flow of protons across the inner membrane from the matrix to the intermembrane space. This process raises the matrix pH. In addition, the matrix becomes negatively charged with respect to the intermembrane space. Protons flow passively into the matrix through a channel in the ATP synthase. This flow is coupled to ATP synthesis. 

The terminal oxidase in an energy-transducing, cytochrome-based electron-transport system maintains electron flow by coupling cytochrome oxidation to dioxygen (O2) reduction. Members of this protein class are referred to as cytochrome oxidases they carry out Oj-binding and redox chemistry at transition metal-containing active sites. Although iron is the most commonly used metal and may occur as a protoheme or iron-chlorin species in the protein, this section is concerned only with mitochondrial cytochrome oxidase, which contains 2 mol of Cn and 2 mol of heme a bound Fe per function unit. Biochemistry of the protein will not be considered here, instead the focus will be on the stmcture of the metal centers, on the reactions they catalyze and on models for these centers. 

Gdmez-Hemandez, J.J. and EF Cassiraga, Impact of flow and transport coupling in the upscaling of transport parameters for perfonmnce assessment in the context of nuclear waste disposal, this volume, 2004. 

Brady, A coupled flow-transport-deformation model for underground coal gasification, this volume, 2004. 

IMPACT OF FLOW AND TRANSPORT COUPLING IN THE UPSCALING OF TRANSPORT PARAMETERS FOR PERFORMANCE ASSESSMENT IN THE CONTEXT... 

A COUPLED FLOW-TRANSPORT-DEFORMATION MODEL FOR UNDERGROUND COAL... 

Not all active transport is brought about by the coupling of two transport flows. It can also be the case that a transport flow is coupled to the progress of a chemical reaction, as we shall now discuss. We saw in Section 3 that there was a very close analogy between the formal description of an enzymatically catalysed chemical reaction and the formal description of transport. We can approach Fig. 11 in the same spirit. Consider countertransport, the left-hand figure. Here, B, and B2 can. 

The previous example was calculated with a common numerical model for flow-and conservative transport. The simulation of natural attenuation processes however, requires three-dimensional transport coupled with complex biochemical and chemical reactions. In the following example the numerical model TBC (Transport, Biochemistry and Chemistry Schafer et al., 1998A) is used to simulate natural attenuation processes in a heterogeneous aquifer. 

In the second approach, the spatially homogeneous chemical slow manifold is used, and the method must somehow accoxmt for reaction-transport coupling. For a chemical timescale to be defined as fast in a reactive flow system, the Damkohler number, which is defined as the ratio of the flow timescale tf and the chemical timescale Tc, must be large ... 

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