Abstract: The present invention relates to a preparation and purification method for cationic quaternary ammonium salt of sodium hyaluronate in homogeneous medium. By adding a homogeneous solvent and a sodium hyaluronate solid to a vessel, heating the vessel until the contents are dissolved to form a homogeneous system, adding an aqueous solution of 2,3-epoxypropyltrimethylammonium chloride (GTA) to the homogeneous system, then adding a base catalyst, and stirring at a preset temperature to carry out a graft reaction, a graft product is obtained wherein 2,3-epoxypropyltrimethylammonium chloride is grafted to the oxygen atom of the hydroxymethyl group of sodium hyaluronate. By using the method, a graft product wherein 2,3-epoxypropyltrimethylammonium chloride is grafted to the oxygen atom of the hydroxymethyl group of sodium hyaluronate is obtained. Addition of salts is avoided during the reaction, a grafting yield up to 0.69 is obtained, and coagulation occurred to the product is effectively solved.

Abstract: The present disclosure relates to a charging guidance method for fast charging loads based on an adjustable and graded charging service fee, including: establishing a fast charging load prediction model based on a trip chain and a Monte Carlo method to predict a fast charging demand and a spatial-temporal trajectory change of a user trip; deciding a charging location based on a weighted user charging location decision model, and calculating a fast charging load of each charging station; constructing a regional graded charging service fee adjustment model with a minimum sum of absolute values of voltage deviations of nodes in the distribution network in a region as an optimization objective, and optimizing and adjusting the charging service fee; and determining an optimal user charging location under fast charging loads by using the weighted user charging location decision model based on the adjusted charging service fee.

Abstract: The present invention relates to a preparation method for acetylated sodium hyaluronate, which pertains to the field of organic chemical synthesis, characterized in that, the preparation method includes the following steps: in the protective atmosphere of inert gas, subjecting a hyaluronate and an acetic anhydride to a catalytic reaction in an organic solvent with a catalyst added, adding a water absorbent during the reaction, obtaining a reaction liquid, subjecting a reaction liquid to post treatment, separation, purification, and drying to obtain a product. A too high or too low degree of substitution is effectively avoided in the present invention, so as to obtain a product with a degree of substitution of acetyl groups ranging from 2.7 to 3.2, with mild reactive materials and reacting conditions, and simple separation and purification steps.