Monovalent cation effects

Multivalent cations affect phase behavior, hence, optimal salinity, more than the effect of an equal molar quantity of monovalent cations and the multivalent to monovalent cation effectiveness ratio increases with decreasing surfactant concentration. Consequently, ion exchange during a chemical flood can influence... 

Monovalent cations are compatible with CMC and have Httle effect on solution properties when added in moderate amounts. An exception is sUver ion, which precipitates CMC. Divalent cations show borderline behavior and trivalent cations form insoluble salts or gels. The effects vary with the specific cation and counterion, pH, DS, and manner in which the CMC and salt are brought into contact. High DS (0.9—1.2) CMCs are more tolerant of monovalent salts than lower DS types, and CMC in solution tolerates higher quantities of added salt than dry CMC added to a brine solution. 

Luciferase-catalyzed luminescence of luciferin. Odontosyllis luciferin emits light in the presence of Mg2+, molecular oxygen and luciferase. The relationship between the luminescence intensity and the pH of the medium shows a broad optimum (Fig. 7.2.8). The luminescence reaction requires a divalent alkaline earth ion, of which Mg2+ is most effective (optimum concentration 30 mM). Monovalent cations such as Na+, K+, and NH have little effect, and many heavy metal ions, such as Hg2+, Cu2+, Co2+ and Zn2+, are generally inhibitory. The activity of crude preparations of luciferase progressively decreases by repeated dialysis and also by concentrating the solutions under reduced pressure. However, the decreased luciferase activity can be completely restored to the original activity by the addition of 1 mM HCN (added as KCN). The relationship between the concentration of HCN and the luciferase activity is shown in Fig. 7.2.9. Low concentrations of h and K3Fe(CN)6 also enhance luminescence, but their effects are only transient. 

The running of parallel reactions of hydrolysis, ammonolysis and depolymerization of apple pectin in aqueous solution of ammonia (IM) at 25 C were investigated. It was examined the effects of monovalent cations (Na, K", NH4 ) and divalent cations (Ca, Mg ) when they were added as chloride salts. It was found that the relative rates of the above mentioned reactions, depend on the nature and concentration of the added salts as well. The chlorides of sodium, potassium and calcium accelerate hydrolysis and depolymerization, while magnesium chloride delays these reactions. Ammonolysis was increased in cases of ammonium chloride addition. 

In such systems as (M, Mj (i/2))X (M, monovalent cation Mj, divalent cation X, common anion), the much stronger interaction of M2 with X leads to restricted internal mobility of Mi. This is called the tranquilization effect by M2 on the internal mobility of Mi. This effect is clear when Mj is a divalent or trivalent cation. However, it also occurs in binary alkali systems such as (Na, K)OH. The isotherms belong to type II (Fig. 2) % decreases with increasing concentration of Na. Since the ionic radius of OH-is as small as F", the Coulombic attraction of Na-OH is considerably stronger than that of K-OH. 

Quantitative calculations of the IMECs of the C=C stretching and C-H bending bands confirmed this trend (Table 1). Furthermore, for Ca2+ and Mg2+ cations the IMEC values exceed those for the free molecules, while for the Na+ ions there is little effect. This indicates a stronger polarization of the C=C bond in ji-complexes of propene with bivalent than with monovalent cations. As follows from Table 1 the IMECs of the C-H stretching vibrations of propene adsorbed by different cations are strongly decreased in comparison with the free molecule. The ratio of the IMECs for C=C and C-H stretching bands is increased for propene adsorbed by Mg2+ cations in comparison with the ratio obtained for the free molecule. 

A similar effect was observed earlier in [5] for ethene adsorption by X zeolite modified with bivalent cations of Cd and Ca. The C-H stretching bands, which are intense for free ethene, are not detectable at low pressure, while the normally forbidden C-H deformation and C=C stretching bands are the strongest in the spectrum. Further, ethene is weakly adsorbed by monovalent cations such as K, Na or Li and the relative intensities of C-H stretching bands are very strong. 

The effects of Li+ upon hematopoiesis have been proposed to be due to two different systems modification of the activity of the membrane Na+/K+-ATPase, and the inhibition of adenylate cyclase. Monovalent cation flux, in particular Na+ transport, is known to influence the differentiation and proliferation of hematopoietic stem cells. For instance, ouabain, an effective inhibitor of the membrane Na+/K+-ATPase, blocks the proliferation of lymphocytes and has been shown to attenuate the Li+-induced proliferation of granulocyte precursors [208]. Conversely, Li+ can reverse the actions of amphotericin and monensin, which mediate Na+ transport and which inhibit CFU-GM, CFU-E, and CFU-MK colony formation in the absence of Li+ [209]. Therefore, the influence of Li+ upon normal physiological cation transport—for example, its influence upon Na+/K+-ATPase activity—may be partly responsible for the observed interference in hematopoiesis. 

The variation of the associated cation has also been investigated for 5-halo-salicylaldehyde thiosemicarbazone compounds [105]. The favouring of the low spin configuration for both (cation) [Fe(5-Br-thsa)2] and (cation) [Fe(5-Cl-thsa)2] follows the order of the associated cations Na+>-Li+>K+>NH4+ even though the effect of variation of the monovalent cation is not very pronounced. Overall the low spin state is favoured to the greater extent in the salts of the 5-chloro derivative. On the other hand, the Zn2+ salt of this derivative, which crystallises as a sesqui hydrate, shows a more extended transition in the range 80-300 K [105]. 

Because soda-glass membranes contain a high proportion of sodium ions, they exhibit a marked response to sodium ions in solution. The effect becomes increasingly significant as the hydrogen ion activity decreases, i.e. at high pH, and it is sometimes referred to as the alkaline error. At pH 12, the error is about 0.3 of a pH unit if the solution is 0.1 M with respect to sodium ions, and 0.7 of a pH unit if the solution is 1 M in sodium ions. Other monovalent cations such as lithium and potassium have a similar but smaller effect. By replacing the sodium in... 

Addition of Lewis acids under the form of monovalent or divalent metal ions produces similar effects,5 as shown in Figure 4.7. Analysis of the reactions metal ion and C02 reaction orders suggests the mechanism depicted in Scheme 4.7 for monovalent cations. The carbene-like adduct is stabilized, in this case by addition of one metal ion and one C02 molecule. 

Lithium remains our most effective treatment for reducing the frequency and severity of recurrent affective episodes, but, despite extensive research, the underlying biological basis for the therapeutic efficacy of this drug remains unknown. Lithium is a monovalent cation with complex physiological and pharmacological effects within the brain. By virtue of the ionic properties it... 

Lithium is a monovalent cation that inhibits several steps in phos-phoinositide metabolism, as well as many second and third messengers, including G proteins and protein kinases. Recent evidence suggests that lithium ultimately stimulates neurite growth, regeneration, and neurogenesis, which is likely related to its therapeutic effect (Coyle et al. 2003 Kim et al. 2004). 

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