Effect of Na+ concentration

Table V. Effect of Na+ Concentrations on the Binding of Ca2+ or Mg2 to PS Vesicles and on Rates of Aggregation ...

Figure 3. Effect of Na+ concentration on bubble—bubble coalescence at 125 °C (open circles represent conditions under which no coalescence took place at the maximum pressure imposed).

Figure 4.42. Ethylene epoxidation on Ag/p"-Al203.101 Steady-state effect of catalyst potential on the selectivity to ethylene oxide at various levels of gas-phase dichloroethane (a) and 3-dimensional representation of the effect of dichloroethane concentration, catalyst potential and corresponding Na coverage on the selectivity to ethylene oxide (b).101 Reprinted with permission from Academic Press.

Protective effect of Na and K against inactivation of Na/K ATPase by high concentrations of 2-mercaptoethanol at high temperatures. Biochim. Biophys. Acta 821, 115-120. 

The circulation conditions obtained in the small laboratory cell cannot be attained in a full-scale cell. The effects of Na+ diffusion to the membrane and non-uniformity in its intracell concentration cannot be entirely eliminated, and a greater decrease in current efficiency will tend to occur at high current densities. 

The X-ray diffraction peaks observed in the range of 3°-10° for the modified clays disappear in the rubber nanocomposites. photographs show predominantly exfoliation of the clays in the range of 12 4 nm in the BIMS. Consequently, excellent improvement in mechanical properties like tensile strength, elongation at break, and modulus is observed by the incorporation of the nanoclays in the BIMS. Maiti and Bhowmick have also studied the effect of solution concentration (5, 10, 15, 20, and 25 wt%) on the properties of fluorocarbon clay nanocomposites [64]. They noticed that optimum properties are achieved at 20 wt% solution. At the optimized solution concentration, they also prepared rubber/clay nanocomposites by a solution mixing process using fluoroelastomer and different nanoclays (namely NA, 10A, 20A, and 30B) and the effect of these nanoclays on the mechanical properties of the nanocomposites has been reported, as shown in Table 4 [93]. 

In the literature, there are several reports that examine the role of conventional fillers like carbon black on the autohesive tack (uncured adhesion between a similar pair of elastomers) [225]. It has been shown that the incorporation of carbon black at very high concentration (>30 phr) can increase the autohesive tack of natural and butyl rubber [225]. Very recently, for the first time, Kumar et al. [164] reported the effect of NA nanoclay (at relatively very low concentration) on the autohesive tack of BIMS rubber by a 180° peel test. XRD and AFM show intercalated morphology of nanoclay in the BIMS rubber matrix. However, the autohesive tack strength dramatically increases with nanoclay concentration up to 8 phr, beyond which it apparently reaches a plateau at 16 phr of nanoclay concentration (see Fig. 36). For example, the tack strength of 16 phr of nanoclay-loaded sample is nearly 158% higher than the tack strength of neat BIMS rubber. The force versus, distance curves from the peel tests for selected samples are shown in Fig. 37. 

Fig. 24. Effect of cation concentration on cinnamaldehyde wave im- 0.1 M lithium hydroxide solutions containing various amounts of neutral salts, experimental points for (1) Li+ (2) Na+ (3) Rb+ (4) Cs+ (5) N(CH8)4+ (6) N(C2H5)4+ theoretical curve for the treatment given by Kastening and HoUeck...

Counterion binding is not a well defined quantity, with various experimental techniques weighing the ion distribution slightly differently. Thermodynamic methods (e.g. ion activities or osmotic coefficients) monitor the free counterion concentration, transport methods (e.g. ion self diffusion or conductivity) the counterions diffusing with the micelle, and spectroscopic methods (e.g. NMR) the counterions in close contact with the micelle surface. Measurement of the effect of Na+ counterions on the symmetric S-O stretching modes would also be expected to be highly dependent on the distance of the counterion from the micelle surface (similar to the NMR method). 

Thus, online measurements of composition are usually limited to some overall property. A typical example is pH, defined as the absolute value of the logarithm of the molar concentration (or, more exactly, activity) of hydrogen ion pH can be measured by exploiting the electric potential established between two proper electrodes immersed in the sample fluid, usually a glass membrane electrode and a reference electrode [15], Notwithstanding the temperature dependence and the alkaline error (at high pH, a marked sensitivity to the effect of Na+ and of other monovalent... 

As two planar phyllosilicate surfaces approach one another, hydrated counterions that may be interposed between the surfaces must lose waters of hydration upon compression by the two approaching surfaces [23]. This loss of hydration water has been credited for the oscillatory behavior discussed in Sec. I. C. The nature of the counterion as well as its concentration impact this behavior. Pashley and Quirk [51] reported on the effect of Na, Ca, and La on the hydration pressure observed between two mica surfaces in a force balance apparatus. They noted that the hydration pressure could be fit to a double-exponential with two characteristic decay lengths... 

The effect of Na+ on the stability of water-in-oil emulsions is exercised mainly through its influence on sodium caseinate. It has been shown that as the surface concentration of casein on oil droplets is increased, the oil-in-water emulsion becomes less susceptible to flocculation/coalescence in the presence of electrolyte. Added NaCl broadens the droplet size distribution at a low casein content (0.25%) but causes this effect at a high casein content (0.5%) only when CaCl2 is added (Dickinson et al., 1984). 

The method of equilibrium foam film allows to study the ( -potential at various aspects by means of the microinterferometric technique (see Chapter 2). For instance, to determine cpo at electrolyte solution/air interface (no surfactant) which is very hard to realise experimentally to find the origin of the surface charge in this case [186,187] to find the isoelectric points at the solution/air interface [173,188] to study the effect of the concentration of various kinds of surfactants [95,100,189,190] ionic effects influence of Na+... 

Whereas most studies have focused on fhe effects of NA on lipid metabohsm, the action of NA on carbohydrate metabohsm is less well understood. After acute NA administration, glucose concentrations have been reported to decrease [435], rise [436] or remain unaltered [437] in rats and humans. Results of glucose tolerance tests after acute NA intake have also been inconsistent [438, 439]. Chronic administration of NA has consistenfly resulted in deterioration of glucose tolerance and elevation of fasting blood glucose concentrations in normal humans [439-441] and impairment of glycemic control in NIDDM patients [440]. These effects are contrary to expectations based on the glucose-FA cycle of Randle and coworkers [38, 39]. If reduction of hpolysis and NEFA availability reduces oxidation... 

The effect of NaOH concentration on the ion transport and rheological properties of the Nafion ion exchange membranes may be attributable to some variation in the ionic domain structure in the presence of NaOH. Therefore, it is extremely Important to understand the ionic domain structure under these conditions. The anomalous behavior of Na" " ion transport as a function of NaOH concentration is seen more frequently in bilayer Nafion membranes in which one layer is treated with diamine and also in perfluorinated carboxylic ion exchange membranes. Several mechanisms have been proposed to explain their ion transport results including water absorption, transport of hydroxide ion tunneling, ion pairing mechanisms, etc. (54-56). As the ion transport properties are beyond the scope of this review, no detailed discussion will be presented. 

Figure 8.20. Effect of NaCI concentration on the c-axis spacing of Na" -saturated smectites having different total layer charge (number labeling curves is the layer charge per unit cell) and percentage of charge in tetrahedral sites (value in brackets). (Adapted from P. G. Slade et al. 1991. Crystalline swelling of smectite samples in concentrated NaCI solutions in relation to layer charge. Clays Clay Min. 39 234-238.)...

DSC, reported that SCN, another chaotropic anion, stabilizes BSA in the same conditions. It is known that SCN binds strongly to BSA [191]. We observed [195] that Ca2+ and Mg2+ decrease QD and Tm of ribulose 1,5-diphosphate carboxylase (Rubisco) to a limited extent but in a definite and steady way as their concentration increases over the ionic strength range 0-0.3 mol/L Na+ and NH+4 had an opposite effect. In the case of Rubisco, specificity of the effect of Ca2+ and Mg2 + is supported by the fact that these cations are known to bind to the protein and to affect its enzymatic activity by inducing structural changes. Specific effects of Na+ and Ca2+ are also observed by DSC on the heat stability of a-lactalbumin [190] they result in a linear increase of QD with the cation/protein molar ratio up to 1, followed by a plateau (Fig. 7). 

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