Sustainable permeability

Figure 10.13 Relationship between specific air demand and sustainable permeability for submerged membrane MBRs (Judd, 2006).

Lester, H. A. Analysis of sodium and potassium redistribution during sustained permeability increases at the innervated face of Electrophorus electroplaques. J. Gen. Physiol. 72, 847—862 (1978). 

The guarded hot-plate method can be modified to perform dry and wet heat transfer testing (sweating skin model). Some plates contain simulated sweat glands and use a pumping mechanism to deUver water to the plate surface. Thermal comfort properties that can be deterrnined from this test are do, permeabihty index (/ ), and comfort limits. PermeabiUty index indicates moisture—heat permeabiUty through the fabric on a scale of 0 (completely impermeable) to 1 (completely permeable). This parameter indicates the effect of skin moisture on heat loss. Comfort limits are the predicted metaboHc activity levels that may be sustained while maintaining body thermal comfort in the test environment. 

The warming up of the mat is performed by the so-called steam shock effect [173,219]. A prerequisite for this is the high permeability of the particle or fiber mat. Higher moisture contents of the face layers and spraying of water sustain this effect. 

Pitt, C. G., Jeffcoat, A. R., Zweidinger, R. A., and Schindler, A., Sustained drug delivery systems. I. The permeability of poly(e-caprolactone), poly(DL-lactic acid), and their copolymers, J. Biomed. Mater. Res., 13. 497-507, 1979. 

The electrophysiological experiments reported here and done with patch-clamp techniques support this idea. The external application of MTX to isolated cardiac myocytes caused a sustained inward current which was carried by Ca . MTX did not increase the voltage-dependent Ca channel current, and both the time dependence and voltage dependence of the MTX-induced current were clearly different from those of the usual Ca channel current. These results suggest that the MTX-induced steady current is different from the usual voltage-dependent Ca channel current, and that this is possibly a current which flows through a new type of Ca -permeable channel. Tbe steady current described here may be responsible for the highly enhanced Ca influx induced by MTX and could account for the excitatory action of MTX on smooth and cardiac muscles. 

Figure 5. The critical absolute permeability necessary to sustain the stability of a static foam as a function of liquid saturation. Calculations are for the constant-charge electrostatic model.

In addition, the authors suggest that all such systems must have a semi-permeable active boundary (membrane), an energy transduction apparatus and (at least) two types of functionally interdependent macromolecular components (catalysts and records). Thus, the phenomenon of life requires not only individual self-replication and self-sustaining systems, but it also requires of such individual systems the ability to develop a characteristic, evolutionary dynamic and a historical collectivist organisation. 

Increased tolerance to copper was observed in fathead minnows after prolonged exposure to sublethal concentrations, but tolerance was not sustained on removal to clean water. Copper tolerance in fathead minnows is attributed to increased production of metallothioneins (Benson and Birge 1985). Copper tolerance in rainbow trout seems dependent on changes in sodium transport and permeability (Lauren and McDonald 1987a). 

The number of wells manifolded to an individual pump primarily reflects the depth to groundwater, but is also in part dependent on the pump size. In low-permeability formations, wells are typically pumped dry. As long as the pumps sustain sufficient vacuum to all wells at the intake depth, LNAPL eventually enters the well and is evacuated. In higher-permeability formations, fluid is pumped consistently from each well at a maximum rate. In both low- and high-permeability formations, individual pumps work harder to pump from greater depths. Decreasing... 

Keywords Colon Controlled release Sustained release Rat Single-pass perfusion Recirculation Closed loop Carrier-mediated transport Passive transport Membrane permeability P-glycoprotein Paracellular pathway Transcellular pathway... 

In sum, the natural tendency will be for sodium, calcium, and chloride ions to flow into the neuron and for potassium ions to flow out, and in so doing to reduce the membrane potential to zero. In reality, this is not so easy. The plasma membrane of the neuron is not very permeable to these ions. If it were, it would be impossible to sustain concentration gradients across it. The rate of passive diffusion of these ions across this membrane is very slow, though not zero, and different for each ion. So how do ions get across the neuronal plasma membrane rapidly There are two ways gated channels and active transport by pumps. 

The electrical potential across a LB film of dioleoyl-lecithin deposited onto a fine-pore membrane, imposed between equimolar aqueous solutions of NaCl and KC1, was reported to exhibit rhythmic and sustained pulsing or oscillations of electrical potential between the two solutions. These oscillations were attributed to the change of permeability of Na+ and K+ ions across the membrane, which originated from the phase transition of lecithin. 

All targets in these tests were secured to a post located in 4 ft of water. Targets were suspended from the post by a rope so that the targets were approximately 1 ft from the seafloor. For initial tests, a target was constructed using a commercially available TNT simulant. The simulant consists of TNT coated onto particles of sand, but the quantity of TNT in the simulant is insufficient to sustain a detonation. This target was placed inside a water-permeable fabric bag and was affixed to the pole as previously described. 

The kitchen of a fast food restaurant is characterized by islands of automation, with well defined subprocesses focused on producing a certain kind of output, coordinated by a crew chief The principal advantage of a fast food restaurant is consistency and fast delivery. The dedicated subunits are designed to perform a certain type of process (assay) at a high rate with very little room for change. Economically, this model is difficult to sustain unless each assay type has sufficient demand to justify the existence of dedicated space, equipment and personnel. It is also not as efficient as a secondary screening model. For assays that are routinely, but not always, requested then this model is very appropriate (e.g., CACO-2 permeability, microsomal stability). However, for the more costly and complex assays that are requested less often, the cost of dedicated people and equipment is hard to justify and as a result the assay has to come off the menu. This is why most fast food restaurants have a relatively limited menu, including mostly foods that are simple to prepare. 

Re-injection into the subsurface is the most often used technique to dispose of geothermal waste heat. The cooled-down fluids, after having fulfilled their tasks in the power generation cycle (or in the direct-use application), can be reinjected into the same geothermal reservoir from which the hot fluid has been produced. The fluid re-injection can help to sustain reservoir pressure, which otherwise would decrease during production. For the re-injection, however, additional wells must be drilled and - if required by the rock permeability at depth - the fluid must... 

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