Equilibrated concentration

Apical membrane Na+/H+ exchange (via NHE3) and bicarbonate reabsorption in the proximal convoluted tubule cell. Na+/K+ ATPase is present in the basolateral membrane to maintain intracellular sodium and potassium levels within the normal range. Because of rapid equilibration, concentrations of the solutes are approximately equal in the interstitial fluid and the blood. Carbonic anhydrase (CA) is found in other locations in addition to the brush border of the luminal membrane. 

The problem with working with separatory funnels is that the separation is generally not complete. Each component has an equilibration concentration in each layer. If we were to draw off the bottom layer and dry it to recover the red dye, we would find it still contaminated with the other component, the blue dye. Repeated washings with fresh lower layer would eventually leave only insignificant amounts of contaminating red dye in the top layer, but would also remove part of the desired blue compound. Obviously, we need a better technique to achieve a complete separation. 

In our example, we separated a purple mixture made up of a polar red dye and a nonpolar blue dye. Adding this mixture to a separatory funnel containing water and hexane and shaking vigorously will produce two colored layers. The upper (hexane) layer will contain the blue (nonpolar) dye. The lower (water) layer will attract the red (polar) dye. Opening the stopcock can draw off the water layer containing the red dye (see Fig. 1.2). Evaporation of the water will yield the more polar red dye. In a similar manner, we can recover the blue dye from the hexane layer left in the separatory funnel. The problem with working with separatory funnels is that the separation is not complete each component has an equilibration concentration in each layer. 

Diffusion tends to equilibrate concentration differences between two reservoirs upon contact fluorine concentration profiles develop at the boundary of the two compartments as a function of time. Studies of the distribution of this trace element in archaeological samples such as bones, teeth or flints allow to gain some age information on the excavated objects of a burial site. The presented technique using beams of accelerated protons allows to measure fluorine diffusion profiles with an excellent space resolution. The surface exposure duration was deduced by the same method for Antarctic meteorites. 

The equilibrated concentration of HDEHP dimer, (HG)2E, can be estimated from the initial HDEHP dimer concentration, (HG 1, and the... 

Two passive processes move water through membranes diffusion and hydrodynamic flow. A semipermeable membrane is a membrane that will allow certain molecules (i.e., water) or ions to pass through it by diffusion. If the concentrations of a substance for which the membrane is impermeable are different on the two sides of the membrane, then water will be transported to equilibrate concentrations, for example, a stream of water toward the higher concentration is driven by osmotic pressure. 

The kinetic equation for the adjustment of receptor occupancy (pt) by a pre-equilibrated concentration of an antagonist [B] with rate of offset k2 upon addition of a fast-acting agonist [A] was derived by Paton and Rang [1] as... 

Pieces of mesocarp tissue were isolated from cucumbers and placed in a brine to give an equilibrated concentration of 0.6% acetic acid, 200 ppm SO (for preservation), and varying concentrations of calcium ion from 1 to 16 rtiM. After equilibration, the degree of pectin methylation in the mesocarp tissue was measured (24) and the concentration of free carboxyl groups in the tissue calculated. The concentration of calcium bound by the tissue was calculated as the difference in calcium concentration between the mesocarp tissue and brine solution as determined by a colorimetric procedure (37, 38). These data were used to construct a Scatchard plot to analyze both the moles of calcium bound per carboxyl group in the tissue and the affinity of calcium binding. 

The equilibrated concentration ratio of the oxidized and reduced forms of a redox protein [ Poxleq/PredleqC— p) >6 obtained, c.g., by spectroscopy, then the E can be evaluated... 

To guarantee a spatially equilibrated concentration in each channel as a result of diffusive mixing between laminar streams, the two flows must spend a sufficiently long time in the serpentine channel that equilibrium is reached. An analytical solution for the concentration at any time in one dimension can give the approximate time required to reach the equilibrium state ... 

With reference to (Strub et al. 2000, 2001), Toyoshima et al. (2008) have re-examined the fluoride complexation of Rf in mixed HF/HNO3 solutions by determining %ads values for Rf and correlating them with the relationship between and %ads for Zr and Hf as in (Haba et al. 2004). The variation of the values of Zr and Hf under static conditions and values of Rf from column chromatography as a function of the equilibrated concentration of free ([F ]eq) is shown in O Fig. 20.21a. The solid, dashed, and dotted curves are results of theoretical calculations by Haba et al. in which the log is related to the formation constants... 

Distribution coefficients, of Zr and Hf under static conditions and those of Zr, Hf, and Rf from column chromatography as a function of the equilibrated concentration of ((NOs leq) at fixed [F ]eq = 3.0 x 10 M. Linear relationships of the log Ka versus log [N03 ]eq for Rf and the homologs are indicated by the solid and dashed lines, respectively (Reproduced with the permission of Oldenbourg Wissenschaftsveriag, Miinchen, (Toyoshima et al. 2008))... 

Figure 3.25. Schematic of a gravimetric instrument to measure multicomponent gas adsorption equilibria. Concentrations of the sorptive gas mixture supplied are assumed to be known. After equilibration, concentrations of the sorptive gas components are determined in a gas chromatograph or mass spectrometer [3.16, 3.20, 3.41],...

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