Effect of monovalent

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. 

Figure 4.10 The effect of monovalent, divalent and trivalent counterions on the hydration state of neutralized poly(acrylic acid). Based on Ikegami (1964).

Lessard, J. G. Fragata, M., Micropolarities of lipid bilayers and micelles. 3. Effect of monovalent ions on the dielectric constant of the water-membrane interface of unilamellar phosphatidylcholine vesicles, J. Phys. Chem. 90, 811-817 (1986). 

Lambrechts SA, Aalders MC, Langeveld-Klerks DH, Khayali Y, Lagerberg JW (2004) Effect of monovalent and divalent cations on the photoinactivation of bacteria with meso-substituted cationic porphyrins. Photochem Photobiol 79 297-302. 

The object of the present investigation was to study systematically the effect of monovalent cations on the lattice vibrations in the synthetic zeolites Linde A and Linde X. It was reasoned that mid-infrared spectroscopy might yield information on cation siting in these zeolites. 

A. Aroti, E. Leontidis, M. Dubois, and T. Zemb. Effects of monovalent anions of the Hofmeister series on DPPC lipid bilayers part I Swelling and in-plane equations of state. Biophys../., 93(5) 1580-1590, 2007. 

Recently, Schultes Spasic, Mohanty and Bartel studied in exquisite detail the effects of monovalent and divalent cations on the conformation order of random RNA sequences [115, 116]. These authors investigated the following questions Can arbitrary RNA sequences fold into a unique structure Is this is an evolutionary property of RNA sequences [115, 116] Schultes et al. utilized biochemical tools, such as lead ion induced cleavage, ultracentrifugation, and gel electrophoretic mobility, to probe the structure of evolved and random RNA sequences [115, 116]. 

Some other recent studies have been concerned with the effects of monovalent cations. Hiraoka and Sugai (1984) showed that one Na(I) ion binds to a specific site in a-lactalbumin, presumably the Ca(II) binding site. The bound Na(I) stabilizes the native form of the protein. Hiraoka and Sugai (1985) reported that both Na(I) and K(I) stabilize the nativelike state of a-lactalbumin. However, the conformational change induced by these ions, from the partially unfolded apo form to the native form, is slow compared to that brought about by Ca(II). 

Marini FP, Arnow P, Lampen JO. The effect of monovalent cations on the inhibition of yeast metabolism by nystain. J General Microbiol 1961. 

To combine the effects of monovalents and divalents, UTCHEM uses the concept of effective salinity, which is defined as... 

House, W.A., The role of surface complexation in the dissolution kinetics of silica Effects of monovalent and divalent ions at 25 °C, J. Colloid Interf. Sci., 163, 379, 1994. 

Effect of Monovalent Ions on Cucumber Softening Rates... 

Kinsky SC. Alterations in the permeability of Neurospora crassa due to polyene antibiotics. J Bacteriol 1961 82 889-897. Marini FP, Arnow P, Lampen JO. The effect of monovalent cations on the inhibition of yeast metabolism by nystatin. J Gen Microbiol 1961 24 51-62. 

The conformational stability of biomolecules is greatly dependent on the solvent species. It is also affected by coexisting solutes such as salts (e.g., NaCl). The salt effects [47, 48, 49] on the solubility and the conformational stability of proteins in aqueous solutions are experimentally known to follow the order called the Hofmeister series. The series for anions is [S04 > CHsCOO" > Cl > Br > NOa" > CIOJ > 1 > CNS ], and that for cations is [(CH3)4N+ > NH > Rb+,K+,Na+, Cs+ > Li+ > Mg + > Ca + > Ba +j. In each of these series, the species to the left decrease the solubility of proteins and stabilize their native structures. The species to the right, on the contrary, increase the solubility and cause destabilization of the native structures. Though the Hofmeister series is not valid for acidic and basic proteins [50, 51], it is generally applicable to neutral proteins. The series, except for divalent cations, is also applicable to the other neutral substances such as benzene [52]. That is, the effects of monovalent ions on the solubility of various neutral substances follow the Hofmeister series. The microscopic mechanisms of these experimentally known properties, however, have not been elucidated yet. 

The effects of monovalent electrolytes on gel time have been reviewed by Mookeijee and Niyogi (219), who reported results on silicic add sols at pH 2.7 where the salt e ect is less marked, whereas most previous work was done at higher pH. The effects of cations to accelerate gelling increased in the order Li, Na, and K and of anions in the order NOj, Cl, Br, and I. For some unexplained reason I" had about fivefold the effect of NOj. The effects were directly proportional to... 

This entry addresses specific ion effects in thin films with thicknesses in the nano- to micrometer range and focuses on the effect of monovalent cations and anions on the structure of thin films. First, thin organic adsorbed films, so-called polyelectrolyte multilayers (PEMs) which are prepared by sequential adsorption of polyanions and polycations on a charged surface [10], are presented. Second, thin liquid (aqueous) films are discussed. These are thin layers of a continuous phase through which the dispersed phase (bubbles, droplets, solid particles) of colloidal dispersions such as foams, emulsions, and suspensions interacts. Both PEMs and liquid films have one thing in common The amount as well as the type of ions plays a central role in determining the properties of such thin films. 

So far, for PEMs mainly the effects of monovalent ions are reported, which follow more or less the Hofmeister series. It is stUl unclear if this simple image as illustrated in Fig. 1 can be generalized to other ion types. Another open question is If the polarizability [25] or rather the ion hydrophobicity [17] presents the decisive parameter. 

Figure 5 shows the effects of monovalent and a divalent cation on the initial foam height of a C14-SME [20]. Again, the effects of water hardness are also shown in the same graph. In soft water, the magnesium and anunonium salts... 

The effect of monovalent and divalent salts on the solubility of these hydrophobically associating polymers (HAPs) is similar to that of ionic surfactants. An increase in salt content decreases solubility. With increasing salinity, the hydrocarbon chains are forced into closer proximity to the point where the subtle balance between hydrophobic associative forces and hydrophilic hydration forces breaks down, and phase separation results. Divalent cations have a larger effect on decreasing polymer solubility than do alkaline earth or monovalent cations. This is particularly so when the polymer contains anionic functionality such as acrylate or sulfonate. Another interesting phenomena occurs in mixed salts with certain polymer compositions when the ratio of divalent to monovalent cation is varied. A window of solubility is observed similar to that found with anionic surfactant solutions. 

Loosley-Millman M, Rand BR, Parsegian VA. (1982) Effects of monovalent ion binding and screening on measured electrostatic forces between charged phospholipid bilayers. BiophysJ40 221-232. 

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