Comparison of salt effects

Another crude model, this time for estimating the strength of tyrosyl-carboxylate interactions, was proposed by Wetlaufer (1956), who showed (1) a qualitatively weak interaction in the miscibility of phenol and aqueous sodium acetate solution, but (2) on the basis of the comparison of the solubility of tyrosine in sodium chloride and sodium acetate solutions, a maximum association constant no greater than 0.10 (assumed binary association) between tyrosine and acetate. By a comparison of salt effects... 

COMPARISON OF SALT EFFECTS. In order to illustrate the effect of dissolved salts on the solubility of both volatile strong electrolytes and neutral species, conditional Henry s law constants Kh, K h are defined for the two solute types such that ... 

Kotze AF, Leeuw BJ, Luessen HL, Boer AG, Verhoef JC, Junginger HE (1998) Comparison of the effect of different chitosan salts and N-trimethyl chitosan chloride on the permeability of intestinal epithelial cells (Caco-2). J Control Release 51 35—46. 

Many of the investigations are carried out at low temperatures and/or at pH values deviating somewhat from neutrality. It has earlier been emphasized that the influence from factors such as temperature, pressure, pH, concentrations, ionic strength, and salt effects must be considered when pressure effects are discussed. This is because conditions that are optimal to one enzyme may be intolerable to another. After all, we are dealing with enzymes from microorganisms, cold-blooded, and warm-blooded animals. Such complications make comparison of pressure effects on enzymes nearly meaningless. 

For comparison with these data, the types of salt effects that have been observed for model protein and polypeptide systems that achieve true thermodynamic equilibrium in solution can be summarized into three classes ... 

In 1965 Bawn and co-workers (2) reported a comparison of the effects of changing the gegenion from SbCl6 to PF6 using trityl and tropylium salts as initiators. These workers made their study in bulk polymerizations at 25° and 50°C. Some of their results at 50 °C. on the effect of gegenion on conversion and rate are shown in Table I. Using... 

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). 

In a comparison of the effect of different salts on the transfer of DNA to nylon (Hybond-N and GeneScreen) and nitrocellulose (BA45) membranes, Allefs et al. (1990) observed that NH4CI or NH4OAC yielded twice as much signal as 10 X SSC, 1 M NaCI or 1 M NaOAc. 

Biswas S, Talukder G, Sharma A. 1999a. Comparison of clastogenic effects of inorganic selenium salts in mice in vivo as related to concentrations and duration of exposure. 12 361-368. 

A comparison of the effect of the 3-benzoyl group and the reported ineffectiveness of the 3-acetyl group, of equally strong electron withdrawing power, on selective reduction of the pyridine ring of pyridine quaternary compounds causes speculation. It would be of interest to determine whether the effect is steric by comparison with a pyridine quaternary salt containing the 3-COC(CH3)3 group. 

Becker DJ, OngembaL-N andHENQUiN J-C (1994) Comparison of the effects of various vanadium salts on fflucose homeostasis in streptozotocin-diabetic rats. Eur J Pharmacol 260 169-175. 

Zinc chloride also showed a catalytic effect (Figure 13) but was not as effective as the potassium catalyst. Kinetic analysis of the rate data gave average values for b of 0.37 and 0.35 at 500 and 1000 psi, respectively, and average values for K of 0.0015 and 0.0039 (Table IV). Figure 13 also shows a direct comparison of relative effectiveness of the zinc and potassium salt catalysts. 

Figure 3 A comparison of the effects of freezing and salt exposure at room temperature on the haemolysis of erythrocytes. Salt concentrations corresponding to decreasing temperatures are indicated constructed from data by Lovelock ...

Lithium salts when used as additives also increase the grafting yields for the same reaction, lithium perchlorate being more efficient that lithium nitrate (Table VII ). A comparison of the effectiveness of acid versus lithium perchlorate in the same grafting reaction Is shown in Table VIII, the salt being more effective than acid only at the lower monomer concentrations l.e. 25%. 

Arumugam, G., Khan, S., and Heiden, P. (2009) Comparison of the effects of an ionic liquid and other salts on the properties of electrospun fibers, 2-poly(vinyl alcohol). Macromol. Mater. Eng., 294, 45-53. 

A careful, direct comparison of the effectiveness of PEG s, gl3 es, crowns, crypts, and ammonium salts as PTC s has been done by Stott, Bradshaw, and Parish. These workers examined the nucleophilic substitution reaction of -nitrobenzyl bromide in chloroform with aqueous sodium thiocyanate, and found the following relative rates 18-crown-6 (1.44), dibenzo-18-crown-6 (1.00), crypt 222 (5.10), tetrabutylammonlum perchlorate (1.29), decaglyme (1.41), and PEG 20,000 (0.83). The author s conclusion that the onium salts and PEG are the catalysts of choice is made obvious by their observation that the crypts cost 30-150/g, 18-crown-6 1.00/g, Adogen 464 (an ammonium salt) 2.8c/g, and Carbowax 20M 3.2c/g. 

E. Czerska, H. Al-Baranzi, J. Casamento, et al., Comparison of the effect of elf fields on cnayc oncogene expression in normal and transformed human cells, In Transection of the Bioelectromagnetic Society, Thirteenth Annual Meeting 1991. Salt Lake City, UT, B-2-14. 

Technology Description To achieve precipitation, acid or base is added to a solution to adjust the pH to a point where the constituents to be removed have their lowest solubility. Chemical precipitation facilitates the removal of dissolved metals from aqueous wastes. Metals may be precipitated from solutions as hydroxides, sulfides, carbonates, or other soluble salts. A comparison of precipitation reagents is presented in Table 7. Solid separation is effected by standard flocculation/ coagulation techniques. 

Complexed arenediazonium salts are stabilized against photochemical degradation (Bartsch et al., 1977). This effect was studied in the former German Democratic Republic in the context of research and development work on diazo copying processes (Israel, 1982 Becker et al., 1984) as well as in China (Liu et al., 1989). The comparison of diazonium ion complexation by 18-crown-6 and dibenzo-18-crown-6 is most interesting. Becker at al. (1984) found mainly the products of heterolytic dediazoniation when 18-crown-6 was present in photolyses with a medium pressure mercury lamp, but products of homolysis appeared in the presence of dibenzo-18-crown-6. The dibenzo host complex exhibited a charge-transfer absorption on the bathochromic slope of the diazonio band. Results on the photo-CIDNP effect in the 15N NMR spectra of isotopically labeled diazonium salts complexed by dibenzo-18-crown-6 indicate that the primary step is a single electron transfer. 

Similarly, concepts of solvation must be employed in the measurement of equilibrium quantities to explain some anomalies, primarily the salting-out effect. Addition of an electrolyte to an aqueous solution of a non-electrolyte results in transfer of part of the water to the hydration sheath of the ion, decreasing the amount of free solvent, and the solubility of the nonelectrolyte decreases. This effect depends, however, on the electrolyte selected. In addition, the activity coefficient values (obtained, for example, by measuring the freezing point) can indicate the magnitude of hydration numbers. Exchange of the open structure of pure water for the more compact structure of the hydration sheath is the cause of lower compressibility of the electrolyte solution compared to pure water and of lower apparent volumes of the ions in solution in comparison with their effective volumes in the crystals. Again, this method yields the overall hydration number. 

BJ Aungst, NJ Rogers, E Shefter. (1988). Comparison of nasal, rectal, buccal, sublingual, and intramuscular insulin efficacy and the effects of a bile salt absorption promoter. J Pharmacol Exp Therap 244 23-27. 

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