Divalent small chains

RNA and the synthetic polynucleotides can be cleaved in the absence of divalent metal ions by basic hydrolysis as shown in Figure C, in which the formation of small oligonucleotides from highly polymeric nucleotide chains is followed. In the absence of divalent metal, the reaction rates are approximately the same for RNA, Poly I, and Poly A. 

For rAn > 1 A and rAn/rMin 2 1.75, i.e. for large divalent cations associated with small trivalent ones, the BaFeF5 structure shows two distinct types of chains a simple one and a branched one185). It should be pointed out that for a ratio rAn/rMui > 2.8 (a and / BaAlF5, BaBF5)186,187), or for larger MIU cations (BaTlFs)188), the structures are no more composed of chains. 

Acylate ions are amphiphilic, and the hydrocarbon chains are able to penetrate fatty (hydrophobic) particles, leaving the surface of the particle ionic. (See Fig. 6-26.) Thus, the particle behaves as a micelle and is readily soluble in water. The sodium and potassium salts of fatty acids are soaps. Soaps have poor detergent properties in hard water because the calcium present in such water causes the micelles to aggregate and precipitate. The divalent calcium ion can act as a bridge between two micelles, but since a micelle is polyvalent, a small amount of calcium relative to the amount of the soap can cause all the micelles to aggregate. 

A number of studies have been reported concerning the solution behavior of some divalent earboxylate complexes ((91) M = Zn, Mn, Pb, Hg, Cd). Krafft points (the Krafft point is the temperature at which micelles become soluble) and critical micelle concentration (cmc) were determined in a variety of long-chain alcohols, and for different earboxylate chain lengths. However, the demonstration of their lyotropic mesomorphism was not clear and it appeared that lamellar phases were induced, although over small ranges of temperature and concentration. 

When a salt of type AY2 is the counterion and Y is the coion) is added to an equilibrated flexible polyelectrolyte chain with a monovalent counterion (Z+), the divalent counterion competitively adsorbs on the polymer backbone by displacing the already adsorbed monovalent counterions. Typical results of this competition and the net effective charge of the polymer are given in Figure 4.13 as functions of the salt concentration Cs, for N = 100 and = 8 X 10 ". As soon as even small amount of divalent counterions are... 

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