Effect on transport

Hollander, D. and Ruble, P.E., P-Carotene intestinal absorption bile, fatty acid, pH, and flow rate effects on transport, Am. J. Physiol, 235, E686, 1978. 

Microstructure Effects on Transport in Reverse Microemulsions John Texter... 

Many research compounds are poorly soluble in water. When very lipophilic molecules precipitate in the donor wells, it is possible to filter the donor solution before the PAMPA sandwich is prepared. On occasion, the filtered donor solution contains such small amounts of the compound that determination of concentrations by UV spectrophotometry becomes impractical. One strategy to overcome the precipitation of the sample molecules in the donor wells is to add a cosolvent to the solutions (Section 7.4.4). It is a strategy of compromise and practicality. Although the cosolvent may solubilize the lipophilic solute molecule, the effect on transport may be subtle and not easy to predict. At least three mechanisms may cause Pe and membrane retention (%R) values to alter as a result of the cosolvent addition. To a varying extent, all three mechanisms may simultaneously contribute to the observed transport ... 

Suggested examples for quick evaluation of the pH effect on transport in different regions of the intestine include ... 

Borup, R. et al., Fuel composition effects on transportation fuel cell reforming, Catal. Today, 99, 263,2005. 

Elabd, Y. A., Walker, C. W. and Beyer, F. L. 2004. Triblock copolymer ionomer membranes. Part 11. Structure characterization and its effects on transport properties and direct methanol fuel cell performance. Journal of Membrane Science 231 181-188. 

Cortis A, Chen Y, Scher H, Berkowitz B (2004) Quantitative characterization of pore-scale disorder effects on transport in homogeneous granular media. Phys Rev E 70, 041108, DOl 10.1103/PhysRevE.70.041108... 

D Khossravi. Drug-surfactant interactions effect on transport properties. J Int Pharm 155 179-190, 1997. 

Grapefruit Juice, Apple Juice, and Orange Juice Effects on Transporters... 

These authors were the first FGSE workers to make extensive use of the concept of free volume 42,44) and its effect on transport in polymer systems. That theory asserts that amorphous materials (liquids, polymers) above their glass transition temperature T contain unoccupied volume randomly distributed and in parcels of sufficient size to permit jumps of small molecules — and of polymer jumping segments — to take place. Since liquids have a fractional free volume fdil typically greater than that, f, of polymers, the diffusion rate both of diluent molecules and (uncrosslinked and unentangled) polymer molecules should increase with increasing diluent volume fraction vdi,. The Fujita-Doolittle expression 43) describes this effect quantitatively for the diluent diffusion ... 

FIGURE 15-36 Control of glycogen synthesis from blood glucose in myocytes. Insulin affects three of the five steps in this pathway, but it is the effects on transport and hexokinase activity, not the change in glycogen synthase activity, that increase the flux toward glycogen. 

This treatment assumes that the forces between molecules in relative motion are related directly to the thermodynamic properties of the solution. The excluded volume does indeed exert an indirect effect on transport properties in dilute solutions through its influence on chain dimensions. Also, there is probably a close relationship between such thermodynamic properties as isothermal compressibility and the free volume parameters which control segmental friction. However, there is no evidence to support a direct connection between solution thermodynamics and the frictional forces associated with large scale molecular structure at any level of polymer concentration. 

In addition to specific carrier features, a number of external factors may also have marked effects on transport rates. The nature of the membrane phase (in particular for liquid or supported liquid [6.10b] membranes) influences the distribution equilibria as well as the stability and selectivity of the complex in the membrane and the cation exchange rates at the interfaces. The nature of the coextracted anion affects transport via a (cationic complex-anion) pair (Fig. 10) simply by modifying the amount of salt extracted into the membrane this amount decreases with higher hydration energy and lower lipophilicity of the anion (for example, chloride compared with picrate). The concentration of salt in the aqueous phase will, of course, affect the amount extracted into the membrane and therefore the transport rates (for illustrations of these effects see for instance [6.1]). 

Reappraisal of the mucosal epithelial space associated with the surface of Hymenolepis diminuta and its effect on transport parameters. Journal of Parasitology, 70 516-21. 

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