The effect of salt concentration

Next, the effect of salt concentration was evaluated. Figure 7.7 shows SEC analysis of AIC incubated for 24 h at 30°C in phosphate buffer pH 7.2 containing various amounts of NaCl. AIC incubated in the absence of NaCl (panel A)... 

Knowing how ion conduction is determined by the interplay between the dielectric constant and viscosity, the dependence of ion conductivity on different variables that are of practical interest can be explained consistently. Extensive studies have been carried out on the effects of salt concentration, solvent composition, and temperature on ion conductivity in... 

The cloud point may be regarded as a limit of solubility, since the turbidity produced is due to HPMC precipitating from solution. Equation (2) was used to determine the effect of salt concentration on the cloud point. Thus,... 

The original equation for salt effect in vapor-liquid equilibrium, proposed by Furter (7) and employed subsequently by Johnson and Furter (8), described the effect of salt concentration on equilibrium vapor composition under the condition of a fixed ratio of the two volatile components in the liquid phase. The equation, derived from the difference in effects of the salt on the chemical potentials of the two volatile components, with simplifying approximations reduces to the form... 

Figure 6. The effect of salt concentration on adsorption capacity for...

Figure 17 presents the results of an FTIR spectroscopic study of the effect of salt concentration on the cmt of 70 mM SDS. As Mantsch et al. (4) have shown in similar work with alkali hexadecylsulfates, the cmt can be related to the sudden increase in frequency of the v9 CH2 bands as a function of temperature. The large increase in the gauche conformer content of the methylene chains of the surfactant tails as they "melt" at the cmt is responsible for this frequency shift. The effect of added salt is to raise the cmt of SDS, which is the cause of the "salting out" of this ionic surfactant at any given temperature. The cmt values, taken as the midpoint of the discontinuities in the frequency-temperature plots, agree well with those obtained by other means (14,54). 

In order to explore the effect of salt concentration on the stability of the active enzyme, the enzymatic activity was determined under standard conditions of 4 M NaCl after exposure of the enzyme for various times to various salt concentrations. If the transition of the enzyme between the active form, Ea, and the inactive form is very slow as compared to the time of the assay (as is the case in AMDH for various lower salt concentrations), the distribution of enzyme molecules between the active and inactive states during the assay reflects that distribution at the end of the preincubation period. For this case, Eq. (2) is reduced to... 

It is tempting to try to explain the halophilic features of ADHFR even in the absence of a detailed kinetic scheme for this enzyme, assuming that the main features of the kinetic scheme of the non-halophilic enzymes hold true also for the halophilic enzyme. The salt concentration might have an effect on the rates of binding or dissociation of the various substrates or on the rate of the hydride transfer reaction. Because, as we saw, the hydride transfer reaction is largely dependent on the protonation of Asp-27, it becomes the rate-limiting step at pH values higher than the pKa of this residue. The effect of salt concentration on the steady-state turnover can be ex-... 

Systematic studies on micellar size and structure have been published for poly(styrene-h-acrylic acid) (PS-PAAc) [7, 8], poly(styrene-fr-sodium acrylate) (PS-PAAcNa) [9], or quaternized poly(styrene-h-4-vinyl-pyridine) (PS-P4VPMeI) [10, 11]. It was concluded that the polyelectrolyte chains in the micellar corona are almost fully stretched [8]. The effect of salt concentration was investigated by Guenoun et al. on poly(f-butylstyrene-fr-sodium styrene sulfonate) (PtBS-PSSNa) who observed a weak decrease of micellar size and aggregation number when the salt concentration was increased beyond 0.01 mol/1 [12]. Using small-angle neutron scattering (SANS), the authors could provide additional support for the rod-like conformation of the polyelectrolyte chains in the micellar corona [13]. 

Zheng JP, Jow TR. The effect of salt concentration in electrolytes on the maximum energy storage for double layer capacitors. Journal of the Electrochemical Society 1997 144(7) 2417-2420. 

The effect of salt concentration on the force is presented in Fig. 3 for a Hamaker constant of 0.5 x 10 20 J. As the salt concentration increases, the force between plates at constant surface potential becomes more attractive at large distances. 

According to the polyelectrolyte character of ODNs, the effect of salt concentration on adsorption should be considered. Indeed, the ionic strength affects (i) the electrostatic interactions between the ODN and the adsorbent and (ii) the lateral repulsive electrostatic interactions between adsorbed ODNs. 

Several mechanistic retention modes in isocratic conditions are described. The effect of salt concentration on HIC at sufficient high ionic strength (/) can be described as... 

FIGURE 14.14. The effect of salt concentration on the degree of extraction of DNA from the aqueous phase into the organic phase. The extraction was performed under the following conditions 10 mM Tris-HCl buffer, pH 8, DNA 50 gAnl, 2C16QA 10 mM and 2-ethylhexylalcohol 5% (v/v) [22]. 

In this paper, we show that the average size is primarily controlled 1 pH, and we show that important limitations are imposed by increasing solubility at high initial salt concentration due to the lower resultant pH. We investigate the effect of salt concentration and of added acid on the final average size, polydispersity, and yield. We use these colloids to make PICA particles and make a comparison with the commercially available colloids. 

The effects of salt concentration on the acid titration curve for wool are illustrated in Fig. 8. The broad isoelectric region observed in the absence of salt becomes less apparent with increasing salt concentration,... 

It would be of interest to test these hypotheses by examining the methanogens and thermophiles for the presence of FAS and acyl transferases and studying the effect of salt concentration, low pH and high temperature on their activities and on those of the mevalonate enzyme system. It may be noted that preliminary studies with M. thermo-autotrophicum have revealed the presence of a functional FAS producing fatty acids for acylation only of membrane proteins (Pugh and Kates, unpublished data). 

The effect of temperature on fluorescence has been studied, as has the effect of salt concentration and water-soluble conjugated polymers. A method for the quantification of ssDNA dsDNA is described, as well as kinetics of mismatch hybridization and the kinetics of collision in short ss-nucleic acids. Fluorescence quenching of Cy-5 labelled oligonucleotides by poly(phenylene ethynylene) particles has been shown to be a more sensitive method than excitation of the Cy-5 fluorophore. An ultrasensitive method for the detection of DNA uses highly fluorescent conjugated nanoparticles, and detection limits below IfM were achieved. DNA transport through a carbon nanotube has also been observed using fluorescence microscopy. " ... 

Electrolyte concentration in solutions can affect the degree of swelling as the osmotic pressures between the external and internal solutions decrease with an increase of the electrolyte concentration (8,12,23,24). When the degree of cross-linking of the resin is lower, the effect of salt concentration variation is more considerable. Ion-exchange resins are generally more swollen by strongly polar solvents than by less polar ones. 

Figure 5. Effect of pH and sodium chloride concentration on the adsorption of phosphate from a solution with an initial concentration of 340 (jM of phosphate and a goethite concentration of 3.1 g/1. Insets show the calculated values for the effects of salt concentration on the electric potential in the plane of phosphate adsorption. The concentration of sodium chloride was O.OIM, O.IM, and l.OM [40].

In terms of equation (1), this would mean a normal distribution of log (Kj). However, it is also possible that there would be heterogeneity in the term of equation(l). Evidence for this is obtained from a study of the effect of salt concentration on adsorption of anions. Fig. 10 shows that there are effects of salt concentration on phosphate sorption by a soil. These effects are analogous to those on phosphate sorption by goethite at low pH, increasing salt concentration decreases sorption at higher pH it increases sorption. There is thus an intermediate pH at which salt concentration has no effect. The value of this point of zero salt effect decreases with increasing sorption as would be expected. However, it occurs at a higher pH than the point of zero salt effect on pH (Fig.ll). 

Gll. Goodman, M., and Wolfe, H., Precipitin production in chickens. VIII. A comparison of the effect of salt concentration on precipitate formation of pheasant, owl and chicken antisera. J. Immunol. 69, 423-434 (1952). 

Rojas OJ, Claesson PM, Muller D, Neuman RD. The effect of salt concentration on adsorption of low charge density polyelectrolytes and interactions between polyelectrolyte coated surfaces. J Colloid Interface Sci 1998 205 77— 88. 

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