– called this point critical weight fraction. – For

– Precipitation is a cheap and simple method to purify/fractionate polysaccharides (Smidsrød & Haug, 1967).

– Precipitation is not possible for all charged polysaccharides, because sometimes the presence of inorganic salts induce the formation of gel (Smidsrød & Haug, 1967).

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– Smidsrød & Haug (1967) observed that the cation effect on precipitation of charged polysaccharides depends much on the type of the polysaccharide charged groups than on its general structure.

– The polysaccharide molecular weight has little importance on its precipitation with salts and ethanol  (Smidsrød & Haug, 1967).

– Mel’nikov, Khan, Lindman, & Jönsson (1999) assumed the dielectric continuum model for the solvent permittivity: the solvent is a structureless medium characterized by its dielectric permittivity only.

– aqueous solution of PRP, using ethanol as cosolvent

– Mel’nikov, Khan, Lindman, & Jönsson (1999) studied the DNA conformation of single stranded DNA in aqueous solution containing a cosolvent. They verified that there were only two DNA conformations: coil and globular. The increase in cosolvent concentration resulted in discrete transition, within a narrow range of solvent concentration. The authors called this point critical weight fraction.

– For various solvents (methanol, ethanol, 1-propanol, 2-propanol, t-butanol and acetone), the conformation of single stranded DNA changes approximately at the same dielectric constant (Mel’nikov, Khan, Lindman, & Jönsson, 1999).

– Reduction in the dielectric constant results in compaction of the DNA chain (Mel’nikov, Khan, Lindman, & Jönsson, 1999).

– DNA condenses when 89-90% of its charged phosphate groups are neutralized. It is also true in presence of cosolvents and salts (Bloomfield, 1996).

– The association between charged macromolecules leads to an increase in the magnitude of its electrostatic potential in the associated state (Picullell, L. & Nilsson, S., 1990).