Resistance, membrane

Mechanism The mechanism of leaching may involve simple physical solution or dissolution made possible by chemical reaction. The rate of transport of solvent into the mass to be leached, or of soluble fraction into the solvent, or of extract solution out of the insoluble material, or some combination of these rates may be significant. A membranous resistance may be involved. A chemical-reaction rate may also affec t the rate of leaching. 

The membrane resistance for CF-EF can be defined by specifying two permeate fluxes as... 

What should be the pressure aeross an ultrafiltration module, in order to achieve a permeate flux of 400 Liter/m -day. The clean membrane resistance is 2.4 X 10 1/m. 

If the pressure drop across a tubular membrane is 2.8 bars, determine the permeat velocity across the membrane module. The thickness and the porosity of the deposit are 2 mm and 40 %, respectively. The average diameter of the partices is 5 microns. The initial membrane resistance is estimated to be 1.7 X 10 1/m. 

Composite aperture-spanning membranes resist electron beam under low-dose conditions A significant increase in the mechanical stability of solid—supported lipid membranes is observed... 

Fig. 1.—Diagrammatic Representation of the Three Steps in the Taste-cell Transduction. Step 1, interaction of stimulus (S) with membrane-bound receptor (R) to form stimulus-receptor complex (SR) step 2, conformational change (SR) to (SR), brought about by interaction of S with R (this change initiates a change in plasma-membrane conformation of taste cells, probably below the level of the tight junction) and step 3, conformational changes of the membrane result in lowered membrane resistance, and the consequential influx on intracellular ionic species, probably Na. This influx generates the receptor potential which induces synaptic vesicular release to the innervating, sensory nerve, leading to the generator potential.

This is not discussed in detail since mechanisms of resistance have been carefully reviewed (Ghannoum and Rice 1999). It was pointed out that resistance has not been associated with modification of the structure. For the 1,2,4-triazoles that have been widely used, their effect is due to inhibition of the synthesis of ergosterol that is the dominant component of fungal cell membranes. Resistance is generally associated with modification of the target enzymes, for example, the epoxidation of squalene (Terbinafine) or 14a-demethylase (Fluconazole). Resistance of Candida albicans to the azole antifungal agent fluconazole demonstrated, however, the simultaneous occurrence of several types of mechanism for resistance (Perea et al. 2001) ... 

Specific cake resistance a ranges from 10 m/kg for easily filtered large particles to lo m/kg for gelatinous cakes. The membrane resistance Rp typically equals 10 to lO" m. Both a and Rp depend on the filtering pressure. 

Equation (20-80) requires a mass transfer coefficient k to calculate Cu, and a relation between protein concentration and osmotic pressure. Pure water flux obtained from a plot of flux versus pressure is used to calculate membrane resistance (t ically small). The LMH/psi slope is referred to as the NWP (normal water permeability). The membrane plus fouling resistances are determined after removing the reversible polarization layer through a buffer flush. To illustrate the components of the osmotic flux model. Fig. 20-63 shows flux versus TMP curves corresponding to just the membrane in buffer (Rfouimg = 0, = 0),... 

Ohmic losses AEohmic originate from (i) membrane resistance, (ii) resistance of CLs and diffusion layers, and (iii) contact resistance between the flow field plates. Although it is common practice to split current-voltage characteristics of an MEA into three regions— kinetic (low currents), ohmic (intermediate currents), and mass transport (high currents) [Winter and Brodd, 2004]—implicit separation of vt Afiohmic is not always straightforward, and thus studies of size and... 

One of the reasons for the small slope of positive wave in curve 1 is the membrane resistance [i in Eq. (2)]. However, the slope is still smaller than the slope of the positive wave in curve 2 even after it has been corrected for the membrane resistance employing R= 1.05 kO cm. The small slope after the correction can be explained by considering that the slope of the positive wave in curve 1 is composed of the slope of the positive wave in curve 2 and that of the final rise in curve 3. The small slopes of the final rise and the final descent in curve 1 are also attributable to the membrane resistance and the composite reactions at two W/LM interfaces. 

In whole tissue or cell monolayer experiments, transcellular membrane resistance (Rm = Pm1) lumps mucosal to serosal compartment elements in series with aqueous resistance (R = P ). The operational definition of Lm depends on the experimental procedure for solute transport measurement (see Section VII), but its magnitude can be considered relatively constant within any given experimental system. Since the Kp range dwarfs the range of Dm, solute differences in partition coefficient dominate solute differences in transcellular membrane transport. The lumped precellular resistance and lumped membrane resistance add in series to define an effective resistance to solute transport ... 

Carbon molecular sieve membranes Resistant to contaminants Intermediate hydrogen flux and selectivity Intermediate hydrogen flux and selectivity High water permeability Pilot-scale testing in low temperature WGS membrane reactor application Need demonstration of long-term stability and durability in practical applications... 

The integral calculates the work done by the membrane resisting the pressure change in the cell. Assuming that the molar volume Vm is constant, the osmotic pressure is given by ... 

Hirst He did when he added noradrenaline. He got a CL response and an increase in membrane resistance. You don t see a cation-selective channel activated by a neuronally released transmitter. 

Tensile membrane behavior requires continuous reinforcement steel to support in-plane stesses. Two-way slabs and flat slabs, with fixed or simple supports, can usually satisfy the requirements for tensile membrane resistance. Design with tensile membrane resistance is the same as for flexural resistance since the moment capacity of the section is used to determine ultimate resistance. Tensile membrane resistance at 8 degree rotation must be at least... 

In many cases, the dynamic amplification factor or the ratio of static load to dynamic load capacity will exceed two. This is because of the concave up shape of the resistance function and the mobilization of membrane resistance at large deflection to thickness ratios. Because of this phenomenon, it is unconservative to assume the blast capacity of polycarbonate glazing to be no less than one half of its static pressure load capacity. 

At very short blast durations, some small area 1-inch thick panes exhibit slightly less blast capacity than panes with larger areas. This occurs because the small panes are acting as linear plates with small deflections under blast loads while the larger panes can mobilize membrane resistance without exceeding the maximum design stress of 9,500 psi. 

Forshaw PJ, Ray DE (1990) A novel action of deltamethrin on membrane resistance in mammalian skeletal muscle and non-myelinated nerve fibres. Neuropharmacology 29 71-81... 

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