5results about How to "The preparation method is safe" patented technology

The application discloses a preparation method and application of a pyridine derivative compound, belongs to the technical field of chemical synthesis, and has the structural formula as shown in the following formula: wherein the R1 group is one of 4-CH3, 4-OCH3, 4-F, 4-Cl and 4-Br; the R2 group is one of -C5H9 and -C6H 11 ; and the R3 group is one of 3-F, 3-H and 3-CH3. The pyridine derivative compound prepared by the application has a pyridine ring as a structural center and has very important medicinal value and is widely applied in the fields of antitumor, anticancer, antibacterial and other biological medicines.

The invention belongs to the technical field of biological enzyme engineering, and particularly relates to a glycosyl transferase mutant and application thereof in synthesis of rebaudioside M. According to the invention, site-directed mutagenesis is carried out on an amino acid sequence SEQ ID NO.1 of wild type glycosyl transferase, and mutants: I29M, L149C and F374C are obtained through screening; the invention also provides a nucleic acid sequence for coding the mutant, an expression vector and a recombinant strain which are used for catalytically converting rebaudioside D to prepare rebaudioside M, and the conversion rate is obviously improved. Experimental results show that under optimized reaction conditions, the mutant can increase the conversion rate of converting rebaudioside D into rebaudioside M to 100%, which is increased by more than 30% compared with a wild type, and the mutant has significant industrial application value.

The application discloses diatomite-derived silicon-carbon negative electrode material and a preparation method thereof and application in lithium ion batteries, and belongs to the technical field of lithium ion battery negative electrode materials. The method discloses the diatomite and the pitch as raw materials by adopting magnesium heat treatment, and the diatomite-derived silicon-carbon negative electrode material is obtained through specific composite process and calcination treatment. The method can uniformly coat the carbon material on the inner and outer surfaces of the porous micron-sized silicon negative electrode, solves the technical problems of the existing silicon-carbon negative electrode material nano-particle agglomeration and the carbon material coating only on the outer surface, and achieves the beneficial effects of further improving the conductivity and structural stability of the composite material.

According to the europium-doped sodium lithium phosphate photoluminescence material and the preparation method thereof, the preparation raw materials and the preparation method are simple, safe and low in cost, a powder sample shows good characteristics of the photoluminescence material, a photoluminescence signal has high sensitivity and stability, and the photoluminescence signal has high sensitivity and stability by adopting the heating temperature of 650-700 DEG C and the heating time of 8-10 h. Higher photoluminescence sensitivity can be obtained; the total photoluminescence response of the synthesized europium-doped sodium lithium phosphate photoluminescence material fluctuates less than 3% within 24 h after irradiation, and the lowest detection limit is 0.68 [mu] Gy, which reaches the international advanced level. According to the invention, the problems of low sensitivity and poor stability of most photoluminescence materials at present can be solved, and a solid guarantee is provided for the accuracy of the material applied to nuclear radiation dose monitoring and traceability.

The application discloses a one-pot preparation method of 3,4,5-trifluorobromobenzene. In an organic solvent, 2,6-difluoroaniline is used as raw material to obtain the product 3,4,5-trifluorobromobenzene through three steps of bromination, diazotization and fluorination at a certain temperature. The method has the advantages of multiple raw material sources, obvious cost advantage, safety and convenience, high total yield, less waste and the like, and is beneficial to industrialization.