Gradient effects

In resting muscle the high concentration of ADP does not decrease the proton gradient effectively and the high membrane potential slows electron transport. ADP, formed when ATP is hydrolyzed by myosin ATPase during contraction, may stimulate electron transport. However, the concentration of ATP (largely as its Mg salt) is buffered by its readily reversible formation from creatine phosphate catalyzed in the intermembrane space, and in other cell compartments, by the various isoenzymes of creatine kinase (reviewed by Walliman et al., 1992). 

The standard wall function is of limited applicability, being restricted to cases of near-wall turbulence in local equilibrium. Especially the constant shear stress and the local equilibrium assumptions restrict the universality of the standard wall functions. The local equilibrium assumption states that the turbulence kinetic energy production and dissipation are equal in the wall-bounded control volumes. In cases where there is a strong pressure gradient near the wall (increased shear stress) or the flow does not satisfy the local equilibrium condition an alternate model, the nonequilibrium model, is recommended (Kim and Choudhury, 1995). In the nonequilibrium wall function the heat transfer procedure remains exactly the same, but the mean velocity is made more sensitive to pressure gradient effects. 

Velocity hydraulic conductivity x hydraulic gradient effective soil porosity... 

Reinjection of coproduced groundwater through the use of wells is commonly used to return the water to the same aquifer and to set up hydraulic barriers in an effort to contain the plume. Injection wells are commonly used in conjunction with withdrawal systems to enhance the recovery of hydrocarbons. Injecting water at appropriate locations will create a pressure ridge to increase the hydraulic gradient effectively toward the withdrawal point. Normally, the water pumped from the recovery wells is used as the injection water and is injected, without treatment. This method provides an economical way of handling the produced water, as well as being beneficial to the recovery effort. 

Xu C, Wu T, Batteas JD, Drain CM, Beers KL, Easolka MJ (2006) Surface-grafted block copolymer gradients effect of block length on solvent response. Appl Surf Sci 252 2529-2534... 

Sass, J. K., Neff, H., Moskovits, M., and Holloway, S. 1981. Electric field gradient effects on the spectroscopy of adsorbed molecules. J. Phys. Chem. 85 621-23. 

This technique eliminates almost all pressure gradient effects found in the other techniques. This is achieved by suspending the rubber bag (containing explosive to be pressed) in the fluid so that it is not in contact with any surface while it is being compressed (Figure 3.3). Isostatic pressing is used for high-performance... 

The expression for the stress tensor (6.7) allows us to investigate the non-linear with respect to velocity gradient effects. We use the normal co-ordinates (1.13) to write equation (6.7) in the form... 

In the higher voltage domain, the concentration-gradient effects are less pronounced due to the large effect of the electric field. In this case, the very-high-field forms of the hopping transport equation can be used with... 

M. Mate, J. H. Fendler, J. J. Ramsden, J. Szalma, and Z. Florvolgyi, Eliminating surface pressure gradient effects in contact angle determination of nano- and microparticles using a film balance, Langmuir 14, 6501-6504 (1998). 

As pointed out by Brevet and Girault [17], this analysis shows that the discussion of SHG data from liquid/liquid interfaces must be cognisant of the possible contributions from the bulk and from field gradients at the interface. However, in the liquid/liquid case, the changes in optical constants from one bulk phase to the other will normally be less marked than that observed in airAiquid experiments. Of course in the limit of the same optical constants for the two phases, there would be no gradient effects but there would also be no reflection. 

Surface tension gradient effects add to the better known phenomena of density-gradient-driven convection, concentration-gradient-driven diffusion and electrical-potential-gradient-driven ion migration, which appear in the existing theory of cells and electrodes. The potential difference of a working cell is affected by all the near electrode effects mentioned here. The experimental and analytical difficulty is to separate the variables. Indeed the fluid mechanical effects stir the electrochemical reaction, and make cause and effect difficult to discern. 

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