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We consider the problems of correct finding of normal quasisolutions of operator equations whose operator is a superposition of linear and nonlinear operators. The nonlinear operator is a modulo operation. In the case where the linear operator is completely continuous, we establish sufficient conditions for the regularization parameter guaranteeing the convergence of the solution of regularized problem to the quasisolution of the exact operator equation depending on the error of the linear operator of the problem. [ABSTRACT FROM AUTHOR]

Guar gum is a polymer that is widely used as a gelling agent for technological liquids in the petroleum industry. In this work, we have studied the potential for the environmentally friendly biodegradation of guar gum by enzymes of basidiomycetes for efficient disposal of oil industry wastes. We compared the enzymatic activity against guar gum of seven basidiomycete strains for the first time, namely Trametes hirsute MT-24.24, Lactarius necator, T. hirsute MT-17.24, Schizophyllum commune MT-33.01, Fomes fomentarius MT-4.05, Fomitopsis pinicola MT-5.21, and T. versicolor It-1. This comparison showed that the preparation based on the Fomitopsis pinicola MT-5.21 fungal mycelium at a concentration of 0.05% provides the most efficient decomposition of a hydraulic fracturing fluid containing guar gum. By varying the enzyme concentration in this fluid, it is possible to control the decrease in its viscosity over time. The developed enzyme preparation is an efficient and environmentally friendly guar gum biodegrader and can serve for processing waste fracturing fluids based on polysaccharides in order to reuse water resources. [ABSTRACT FROM AUTHOR]