Effective elongation

In a new synthesis of KDO, D-mannose, which has all of the asymmetric carbons, was effectively elongated by a two-carbon unit by condensation of its 6-di-O-isopropylidene furanose derivative with 5-lithio-2,3-dihydro-1,4-dioxin as a key step <89MI 609-02). 

Figure 29. Maximum value of effective elongational viscosity vs. solution con-centration. The extrapolated value o/C 0.064% is indicated by an arrow a-PS-decahydronaphthalene, Mw4 x JO ).

Tamura J, Tokuyoshi M (2004) Synthesis of chondroitin sulfate E hexasaccharide in the repeating region by an effective elongation strategy toward longer chondroitin oligosaccharide. Biosci Biotech Biochem 68 2436-2443... 

Regardless of the monomers from which these various thickeners are made, certain characteristics are common for all. For example, all require neutralization of their carboxylic functionality with base to facilitate effective elongation of the polymer chains. The choice of the neutralizing base can influence the rheology of these polymers in a formulation (Table 2 and Fig. 21) (47,50,55). Because the polymers are optimally cross-linked they will disperse but not fully dissolve. 

Auxin ( 8-indolylacetic acid) is a phytohormone that effects elongation of cells. It is formed in the apex of the plant, especially the germinal shoot, and promotes stretching of the basally located cells. Auxin is also involved in the various tropisms of the plant. 

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