Abstract: Provided are transaminase mutants and uses thereof. The transaminase mutant is obtained by one or more amino acid mutations occurring in SEQ ID NO: 2 or is a mutant with a conserved amino acid mutation obtained by taking the sequence SEQ ID NO: 1 of a wild-type CvTA transaminase as a reference. Compared with wild-type transaminases, the catalytic activity of the mutant is improved to different degrees, so that the production efficiency of chiral amine compound synthesis may be improved.

Abstract: Provided is a method for synthesizing a chiral amine compound. A transaminase is used to transaminate a ketone substrate under the action of an amino donor, to obtain the chiral amine compound; and the conserved amino acid sequence region of the transaminase at least includes a region 1 (MAGLWCVN) and a region 2 (YNTFFKT). With the transaminase with the specific conserved amino acid sequence region to synthesize a large sterically hindered chiral amine, the enzyme catalytic reaction volume is small, the synthesizing route is short, the product yield is high, a high-cost noble metal is not required for catalysis under the synthesizing conditions, three wastes are reduced, and the production cost is saved.

Abstract: The invention discloses a ternary positive electrode material coated with nitride/graphitized carbon nanosheets and preparation method thereof. The ternary positive electrode material coated with nitride/graphitized carbon nanosheets includes a ternary positive electrode material matrix and a coating layer; the coating layer is composed of nitride and graphitized carbon; and the graphitized carbon is formed in situ in the coating process of the nitride. Compared with a physical mixing method, the in-situ generated carbon layer is connected to the material matrix more tightly, and the formed conductive network is denser. So that the rate performance of the material is improved to the maximum extent. The preparation method is simple and easy to realize industrial production. And the obtained ternary positive electrode material coated with nitride/graphitized carbon nanosheets has excellent rate performance and cycling stability.

Abstract: The invention discloses a continuous hot rolled coil for a high collapse-resistant SEW petroleum casing and a manufacturing method thereof, and belongs to the technical field of hot continuous rolling production. Provided is a continuous hot rolled coil for a high collapse-resistant SEW petroleum casing with low alloy element cost and excellent initial welding property, and a manufacturing method thereof. The production cost of the hot continuous rolled coil is lowered by reducing expensive alloy elements such as Mo and V therein, and strictly controlling the content components of chemical elements such as Cr, Mn and Ti.

Abstract: A method for preparing an amplicon library for detecting the variation in a region to be tested of a target gene of a sample, including the following steps: 1) designing and synthesizing a forward outer primer F1, a forward inner primer F2, and a reverse primer R according to the target region; 2) carrying out a one-step PCR amplification on the sample to be tested using the forward outer primer F1, the forward inner primer F2, and the reverse inner primer R to obtain an amplified product, i.e., the amplicon library of the target region. This one-step library preparation technology can be applied to all second-generation platforms including IonTorrent, illumina and BGI/MGI platforms. Based on the library preparation method, the present invention has developed detection products for SNP, Ins/Del, CNV and methylation of DNA, as well as detection products for s gene fusion and expression of RNA samples.

Abstract: The invention discloses a method for preparing an amplicon library for detecting a low-frequency mutation of a target gene. The invention provides a method for preparing an amplicon library for detecting a low-frequency mutation of a target gene, comprising the following steps: 1) design and synthesize a Barcode primer F1, an forward primer F2, a reverse outer primer R1, and a reverse inner primer R2; 2) perform a one-step PCR amplification on the cfDNA of the sample to be tested using the Barcode primer F1, the forward primer F2, the reverse outer primer R1, and the reverse inner primer R2 to obtain an amplified product, which is a DNA library for an amplicon sequencing. In addition to detect tissue samples, the method can also quickly, easily, sensitively and specifically amplify different target regions of cell free DNA from samples such as blood, urine, and CSF, and efficiently detect mutations as low as 0.1%.

Abstract: The invention discloses a continuous hot rolled coil for a high collapse-resistant SEW petroleum casing and a manufacturing method thereof, and belongs to the technical field of hot continuous rolling production. Provided is a continuous hot rolled coil for a high collapse-resistant SEW petroleum casing with low alloy element cost and excellent initial welding property, and a manufacturing method thereof. The production cost of the hot continuous rolled coil is lowered by reducing expensive alloy elements such as Mo and V therein, and strictly controlling the content components of chemical elements such as Cr, Mn and Ti.

Abstract: A method for preparing polymethylene polyphenyl polycarbamate is provided. The method includes dissolving phenylcarbamate in a water-immiscible organic solvent to form a solution A, formulating an aqueous acid catalyst solution to form a solution B, forming a reaction system comprising an organic phase and an aqueous phase by firstly adding a methylating reagent to the solution B and then mixing the solution A and the solution B, wherein the organic phase comprises phenylcarbamate and the aqueous phase comprises the acid catalyst and the methylating reagent. The method further includes reacting the reaction system under stirring at a reaction temperature of 30° C. to 200° C. and a reaction pressure of 0.05 MPa to 5 MPa to produce a polymethylene polyphenyl polycarbamate product mixture dissolved in the organic phase, and separating the polymethylene polyphenyl polycarbamate product mixture by allowing the organic phase and the aqueous phase to stand still and stratify.

Abstract: A method for preparing polymethylene polyphenyl polycarbamate is provided, which is carried out through the condensation of phenylcarbamate with a methylating reagent under the catalyzation of a phase transfer acid catalyst. The method comprises: dissolving phenylcarbamate in a water-immiscible organic solvent to form a solution A; formulating an aqueous acid catalyst solution to fibrin a solution B; forming a reaction system comprising an organic phase and an aqueous phase by firstly adding a methylating reagent to the solution B and then mixing the solution A and the solution B or by adding the methylating reagent at the same time of mixing the solution A and the solution B or after mixing the solution A and the solution B; reacting the reaction system under stirring at a reaction temperature of 30° C. to 200° C. and a reaction pressure of 0.