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The preparation of carboxymethyl (CM)-Cassia tora gum (CTG) with monochloroacetic acid and sodium hydroxide was investigated under different reaction conditions. The carboxymethylation reaction was studied with respect to the degree of substitution of CM-CTG. The variables studied were the concentration of reactants, methanol-water ratio (solvent), reaction time, and reaction temperature. Carboxymethylation of CTG increased its solubil-ity in cold water and the stability of its paste to microorganisms. Regardless of the degree of substitution of these products, their aqueous solutions were characterized by non-Newtonian pseudoplastic behavior. Determination of the rheological properties of CM-CTGThe rheological properties were determined with a Brookfield digital viscometer (model RVTD, Stough-Correspondence to: V. Kumar (vineetkmadan@yahoo.co.in) or P. L. Soni (sonipl@icfre.org).

We propose a general strategy to stabilize the fixed points of nonlinear oscillators with augmented dynamics. By using this scheme, either the unstable fixed points of the oscillatory system or a new fixed point of the augmented system can be stabilized. The Lyapunov exponents are used to study the dynamical properties. This scheme is illustrated with a chaotic Lorenz oscillator coupled through an external linear dynamical system. The experimental demonstration of the proposed scheme to stabilize the fixed points is also presented.