Directional transport

At very high dopant concentrations, transport occurs direcdy between the dopant molecules. The polymer acts only as a binder in most cases. Taking TPD-doped PVK as an example, at low TPD concentrations the hole mobihty first decreases from 3 x 10 cm /Vs to 10 cm /Vs with increasing TPD concentration, because TPD molecules act as hole traps (48,49). At higher TPD concentrations, new direct transport channels between the TPD molecules open up and the hole mobihty increases to lO " cm /Vs for ca 60% TPD doping (Table 1, entries 9—11) (48,49). In this case, there is no evidence for unusual interaction between TPD and PVK that affects the hole transport process. 

Arrangements to direct transporters to reduce consumption if it is impossible to prevent a gas emergency developing. 

In addition, some COg is directly transported by hemoglobin in the form of carbamate (—NHCOO ). Free a-amino groups of Hb react with COg reversibly ... 

The NHR contains also the conserved Calcineurin docking site, PxlxIT, required for the physical interaction of NEAT and Calcineurin. Dephosphorylation of at least 13 serines residues in the NHR induces a conformational change that exposes the nuclear localization sequences (NLS), allowing the nuclear translocation of NEAT. Rephosphorylation of these residues unmasks the nuclear export sequences that direct transport back to the cytoplasm. Engagement of receptors such as the antigen receptors in T and B cells is coupled to phospholipase C activation and subsequent production of inositol triphosphate. Increased levels of inositol triphosphate lead to the initial release of intracellular stores of calcium. This early increase of calcium induces opening of the plasma membrane calcium-released-activated-calcium (CRAC) channels,... 

This discussion suggests a rapid and relatively direct transport of organic material vertically through the ocean water column. However, this transport is not efficient and under "average" ocean conditions (primary productivity = 100 g C/m per year and water... 

A small flux is shown between the land and atmosphere. This represents the transport of dust particles to the atmosphere (F28) and the deposition of these particles back on land either as dry deposition or associated with atmospheric precipitation (F82). Similarly, fluxes that represent the transport of seasalt from the surface ocean to the atmosphere (Fss) and the deposition of soluble (F85) and insoluble (F81) atmospheric forms are also shown. As already discussed for the river fluxes, the insoluble particulate flux is represented as a direct transport of P to the sediment reservoir. 

The emf of the cell, contrary to that in the absence of a liquid junction, depends on the transference numbers. Such cells are usually identified as concentration cells with presence of transference, the second one in the electrolyte concentration cell classification list. This system, as has been seen, contains a liquid junction across which it is possible for direct transport of ions to occur. 

DHT may occur over different tryptophan forms in proteins as they quite often have inhomogeneously broadened electronic spectra [31]. A very interesting case of DHT is described between two indole rings in bichromophoric solutes tryptophan dipeptide [32]. Such directed transport allows to correctly interpret spectral properties of dipeptide and other multichromophoric solutes. The theory of inductive-RET in solutions with inhomogeneous spectral broadening is given in Ref. [33]. In more detail, DHT mechanism will be explained in Sect. 2.2 (vide infra). 

Ungell, and P. Artursson. pH-dependent bi-directional transport of weak basic drugs across Caco-2 monolayers, submitted. 

A. H., Meijer, D. K., Heterologous expression of various P-glycoproteins in polarized epithelial cells induces directional transport of small (type 1) and bulky (type 2) cationic drugs, J. Pharmacol. Exp. Ther. 1998, 286, 321— 327. 

MDRl-directional transport ratio (B/A)/(A/B). b Passive permeability flO cm/s). 

There are three types of mass transport processes within a microfluidic system convection, diffusion, and immigration. Much more common are mixtures of three types of mass transport. It is essential to design a well-controlled transport scheme for the microsystem. Convection can be generated by different forces, such as capillary effect, thermal difference, gravity, a pressurized air bladder, the centripetal forces in a spinning disk, mechanical and electroosmotic pumps, in the microsystem. The mechanical and electroosmotic pumps are often used for transport in a microfluidic system due to their convenience, and will be further discussed in section 11.5.2. The migration is a direct transport of molecules in response to an electric field. In most cases, the moving... 

Recently, the importance of large particle formation and their subsequent rapid transport to abyssal depths of the oceans have been invoked as a mechanism to explain the distribution of several oceanic variables [60]. These studies have shown that there exists a direct transport path between sea surface and sea floor and that the sea floor can no longer be considered remote from the surface. This transport path may become significant for... 

The direct transport of absorbed drugs into systemic circulation, effectively by-passing the first-pass effect of the liver and gastrointestinal tract Lower enzymatic activity compared to the gastrointestinal tract or liver Amenability to self-medication, which increases patient compliance Possibility of pulsatile delivery of some drugs to simulate the biorhythmic release of these drugs Lower risk of overdosage Achievement of controlled release... 

Dekkers, D. W. C., Comfuiius, P., Schroit, A. J., Bevers, E. M. andZwaal, R. F. A., 1998, Transbilayer movement ofNBD-labeled phospholipids in red blood ceU membranes outward-directed transport by the multidrug resistance protein 1 (MRPl). Biochemistry,... 

Water motion in the ocean is the result of two general phenomena, advection and turbulence. Advection causes water to experience large-scale net displacement (directed transport), whereas turbulent mixing involves the random motion of water molecules... 

Active transporters are thought to play an important role in the pharmacokinetics of drugs, not only because they can regulate the permeability of drugs as substrate-specific efflux or influx pumps, but also because of their widespread presence across in vivo membrane systems, from the intestinal epithelia to the BBB. Generally speaking, the absorption direction transporters tend to have narrower substrate specificity than the excretion direction transporters. Active transporters also play a significant role in biliary and renal excretion. 

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