Abstract: This application discloses a key generation method and apparatus, a device, and a medium. The method includes transmitting a key negotiation request to a consensus node in a blockchain network, to request a key verification parameter; negotiating a collaboration key pair with a second device to obtain a first private key component and a shared public key in the collaboration key pair; signing the key verification parameter by using the first private key component, to obtain a first signature component; generating transaction data according to the first signature component and the key verification parameter; transmitting the transaction data to the second device. The consensus node performs a consensus on the negotiation result data, and after the negotiation result data passes the consensus, submits the negotiation result data to a blockchain of the blockchain network.

Abstract: The present disclosure relates to a nitrogen-doped porous carbon material and a preparation method and use thereof. In the present disclosure, the preparation method of a nitrogen-doped porous carbon material includes the following steps: conducting carbonization on a biomass material to obtain a carbon source; and mixing the carbon source with a potassium 4-aminobenzoate aqueous solution, and drying and conducting calcination in a protective atmosphere sequentially to obtain the nitrogen-doped porous carbon material. In the preparation method, the potassium 4-aminobenzoate is used as a nitrogen source as well as an activator for preparing the nitrogen-doped porous carbon material. Nitrogen doping is simultaneously completed during the activation, and the nitrogen-doped porous carbon material can be prepared through one-step calcination.

Abstract: The invention belongs to the field of cosmetic biotechnology, and specifically relates to an Enterobacter that degrades hyaluronic acid and a cultivation method and application thereof. The Enterobacter sp. CGJ001 of the present invention was deposited in the China General Microbiological Culture Collection Center on Oct. 10, 2019, and the preservation number is CGMCC NO. 18661. The Enterobacter strain can efficiently produce hyaluronidase, and can be used in the process of preparing low molecular hyaluronic acid and oligomeric hyaluronic acid from high molecular hyaluronic acid. The enzyme has high specificity towards hyaluronic acid, excellent thermal stability and pH stability, and is suitable for large-scale industrial application. Thus, it can replace the traditional hyaluronidase extracted from expensive animal tissues. There should be broad application prospects in the fields of medicine and cosmetics.

Abstract: The invention belongs to the field of cosmetic biotechnology, and specifically relates to an Enterobacter that degrades hyaluronic acid and a cultivation method and application thereof. The Enterobacter sp. CGJ001 of the present invention was deposited in the China General Microbiological Culture Collection Center on Oct. 10, 2019, and the preservation number is CGMCC NO. 18661. The Enterobacter strain can efficiently produce hyaluronidase, and can be used in the process of preparing low molecular hyaluronic acid and oligomeric hyaluronic acid from high molecular hyaluronic acid. The enzyme has high specificity towards hyaluronic acid, excellent thermal stability and pH stability, and is suitable for large-scale industrial application. Thus, it can replace the traditional hyaluronidase extracted from expensive animal tissues. There should be broad application prospects in the fields of medicine and cosmetics.

Abstract: The present invention provides a phospholipase D having an amino acid sequence as shown in SEQ ID NO. 1, and further provides a gene sequence encoding phospholipase D, which has a nucleotide sequence as shown in SEQ ID NO. 2. The present invention also provides a method for improving the expression level of phospholipase D by systematically engineering the expression elements. The method comprises screening and replacement of signal peptides, ribosome binding sites and promoters. The constructed recombinant plasmid is transformed into a host cell, and the recombinant strain is capable of successfully expressing phospholipase D. The phospholipase D of the present invention has a good phosphatidyl transferring ability, and can be used for synthesizing the product phosphatidylserine with lecithin and L-serine as substrates. The recombinant strain has good stability of enzyme activity and short fermentation period, which lays the foundation for large-scale industrial production.

Abstract: In view of the existing problems affecting computer performance due to poor CPU cooling, this disclosure provides a motherboard arrangement method for improving the performance of the computer and a motherboard thereof, CPU being arranged on the back side of the circuit board, memory slots, expansion slots, peripheral interfaces and other components being arranged on the front side of the circuit board. The heat generated by CPU is directly transferred into a space between the back side of the motherboard and the corresponding side of the case through the cooling fan, the effective cooling and insulation space is formed in the case. It is easy for air circulation, to exhaust hot air outside the case by the power fan, and to make the cold air outside the case inside to improve the cooling efficiency greatly.

Abstract: The invention belongs to the field of cosmetic biotechnology, and specifically relates to an Enterobacter that degrades hyaluronic acid and a cultivation method and application thereof. The Enterobacter sp. CGJ001 of the present invention was deposited in the China General Microbiological Culture Collection Center on Oct. 10, 2019, and the preservation number is CGMCC NO. 18661. The Enterobacter strain can efficiently produce hyaluronidase, and can be used in the process of preparing low molecular hyaluronic acid and oligomeric hyaluronic acid from high molecular hyaluronic acid. The enzyme has high specificity towards hyaluronic acid, excellent thermal stability and pH stability, and is suitable for large-scale industrial application. Thus it can replace the traditional hyaluronidase extracted from expensive animal tissues. There should be broad application prospects in the fields of medicine and cosmetics.

Abstract: The invention relates to the technical field of industrial biotechnologies, and discloses a keratinase mutant with improved thermal stability and use thereof. The asparagine at position 181, the tyrosine at position 217, and the serine at position 236 in the keratinase derived from Brevibacillus parabrevis (CGMCC No. 10798) are engineered by site-direction mutation, and combined at random to obtain an enzyme with combined mutations. The invention realizes the remarkable improvement of the thermal stability of keratinase, and has good theoretical value and application prospect.

Abstract: The present invention provides a phospholipase D having an amino acid sequence as shown in SEQ ID NO. 1, and further provides a gene sequence encoding phospholipase D, which has a nucleotide sequence as shown in SEQ ID NO. 2. The present invention also provides a method for improving the expression level of phospholipase D by systematically engineering the expression elements. The method comprises screening and replacement of signal peptides, ribosome binding sites and promoters. The constructed recombinant plasmid is transformed into a host cell, and the recombinant strain is capable of successfully expressing phospholipase D. The phospholipase D of the present invention has a good phosphatidyl transferring ability, and can be used for synthesizing the product phosphatidylserine with lecithin and L-serine as substrates. The recombinant strain has good stability of enzyme activity and short fermentation period, which lays the foundation for large-scale industrial production.

Abstract: The invention relates to the technical field of industrial biotechnologies, and discloses a keratinase mutant with improved thermal stability and use thereof. The asparagine at position 181, the tyrosine at position 218, and the serine at position 236 in the keratinase derived from Brevibacillus parabrevis (CGMCC No. 10798) are engineered by site-direction mutation, and combined at random to obtain an enzyme with combined mutations. The invention realizes the remarkable improvement of the thermal stability of keratinase, and has good theoretical value and application prospect.

Abstract: The present invention discloses a directionally modified glucosamine synthase mutant and its application. The amino acid sequence of the glucosamine synthase mutant is as shown in sequence list SEQ ID No. 1, and the nucleotide sequence is as shown in sequence list SEQ ID No. 2. The genetic engineering bacteria of glucosamine synthase is successfully constructed. In order to improve the tolerance of recombinant bacteria against glucosamine, the glucosamine synthase is directionally modified. A glucosamine synthase mutant is selected from the mutant library via high-throughput screening method, the amino acid changes in the mutant induces the spatial conformational change in the enzyme, so as enlarged the region where the enzyme and substrate combines, therefor the combination efficiency of the enzyme and the substrate is increased. The glucosamine synthase of the present invention has various advantages, such as rich in raw material of glucose, and a convenient subsequent extraction.

Abstract: The present invention discloses a directionally modified glucosamine synthase mutant and its application. The amino acid sequence of the glucosamine synthase mutant is as shown in sequence list SEQ ID No. 1, and the nucleotide sequence is as shown in sequence list SEQ ID No. 2. The genetic engineering bacteria of glucosamine synthase is successfully constructed. In order to improve the tolerance of recombinant bacteria against glucosamine, the glucosamine synthase is directionally modified. A glucosamine synthase mutant is selected from the mutant library via high-throughput screening method, the amino acid changes in the mutant induces the spatial conformational change in the enzyme, so as enlarged the region where the enzyme and substrate combines, therefor the combination efficiency of the enzyme and the substrate is increased. The glucosamine synthase of the present invention has various advantages, such as rich in raw material of glucose, and a convenient subsequent extraction.