3194 results about "High activity" patented technology

The invention discloses a high-strength and high-toughness aluminum nitride ceramic and a preparation method thereof, and relates to the technical field of ceramics, a sol-gel method is adopted to coat the surface of aluminum nitride with a stable shell layer to form a core-shell structure, meanwhile, the low lattice mismatch rate of a core-shell interface is utilized to reduce thermal resistance, and toughness and thermal conductivity are both considered; according to the external magnetic field tape casting method, the magnetic dipole moment orientation principle is utilized, an external magnetic field is applied in the tape casting stage, the in-plane mechanical property is improved, and the fracture toughness is improved through the magnetism of aluminum nitride whiskers; a reinforcement is introduced to improve the mechanical property and corrosion resistance of the aluminum nitride ceramic material, multi-granularity powder is compounded, large-particle aluminum nitride powder is used as a sintering and heat-conducting framework material, and high activity provided by submicron particles is utilized to promote sintering, so that the sintering temperature of aluminum nitride can be remarkably reduced, and the performance is greatly improved; and the aluminum nitride substrate expands more application fields on a future packaging circuit.

The invention belongs to the technical field of calcium hydroxide preparation, and particularly relates to a preparation method of calcium hydroxide with high specific surface area, which comprises the following steps: S1, adding triethanolamine and diethanolisopropanolamine into water, and uniformly mixing to obtain an active agent solution; s2, mixing quick lime with an active agent solution, and carrying out digestion reaction to generate a calcium hydroxide coarse material; and S3, sieving and drying the calcium hydroxide coarse material to obtain the calcium hydroxide with the high specific surface area. The specific surface area of calcium hydroxide can be remarkably increased through the active agent solution, meanwhile, the uniformity and sufficiency of the quick lime digestion reaction are optimized, the calcium hydroxide particle aggregation phenomenon is reduced, and finally the calcium hydroxide product with the high specific surface area and the high activity is prepared.

The invention discloses a peptide with a bone strengthening effect as well as a preparation method and application thereof, and relates to the field of biology. The casein is used as a raw material, the high-activity calcium ion chelating peptide and the directional preparation technology thereof are provided, the technology has the advantages of being high in efficiency, low in cost, easy to operate, good in stability and the like, the high-activity calcium ion chelating peptide can be prepared on a large scale, the utilization value of the casein is improved, and a new way is provided for development of functional natural calcium supplement products.

The invention discloses a rare-earth metal arylamine group compound as well as preparation method and application thereof. The invention discloses the rare-earth metal arylamine group compound which is characterized in that a general formula of the rare-earth metal arylamine group compound is (2,6-R12PhNH)5LnLi2(THF)2, wherein Ln is a rear-earth metal selected from one of neodymium, samarium, ytterbium or yttrium; R1 is selected from one of hydrogen, methyl or isopropyl. The rare-earth metal arylamine group compound has the advantages that the rare-earth metal arylamine group compound has a definite structure; raw materials used in the preparation method are simple, easily obtained and cheap; the reaction process is simple and easily operated; the rare-earth metal arylamine group compound product is conveniently purified and the yield of the product is high; the rare-earth metal arylamine group compound has a high activity when acting as a single component catalyst to catalyze a hydrogen phosphine reaction of aldehyde or ketone and phosphite ester; the use amount of the catalyst is less; the yield is high; a substrate has wide universality; a new and simple method is provided for synthesis of a-hydroxyphosphonate.

The invention discloses a high-stability hydroxysteroid dehydrogenase mutant, a co-immobilized enzyme construction method and application. According to the invention, a site-directed mutant library is constructed based on computer-aided design, and mutants with significantly improved thermal stability and greatly improved catalytic efficiency compared with wild type mutants are obtained through screening; meanwhile, a co-immobilized enzyme construction method based on electrostatic adsorption and chemical crosslinking is established, the hydroxysteroid dehydrogenase mutant and lactic dehydrogenase are co-immobilized, the co-immobilized enzyme can still keep high activity under high substrate concentration, and the conversion rate is still maintained to be 90% or above after 30 batches of co-immobilized enzyme are repeatedly used. And an important foundation is laid for industrial application of the hydroxysteroid dehydrogenase.

The invention discloses an inositol dehydrogenase mutant and a preparation method of D-chiral inositol, and belongs to the technical field of genetic engineering. The inositol dehydrogenase mutant is obtained by mutating an amino acid sequence as shown in SEQ ID NO.2 through the following mutations: the 200th amino acid is mutated into C from V, the 234th amino acid is mutated into Q from V, and the 256th amino acid is mutated into E from R. According to the invention, the amino acid sequence of wild type inositol dehydrogenase is mutated to obtain the inositol dehydrogenase mutant which is a high-activity mutant capable of catalyzing conversion of myo-inositol into 2-keto-myo-inositol; therefore, when the inositol dehydrogenase mutant and keto isomerase act together to prepare D-chiral inositol by taking myo-inositol as a substrate, the yield of the D-chiral inositol is effectively improved.

The invention belongs to the technical field of petroleum processing, and particularly relates to a catalyst and a preparation method and application thereof. The raw materials of the catalyst comprise a metal active component, a carrier and an auxiliary agent, the metal active component is sulfides of Mo and Ni elements, the carrier is spherical gamma-Al2O3 of 0.5-1 mm, and the auxiliary agent is P; the carrier is modified by using the metal active component and the auxiliary agent to serve as the catalyst. The high-activity catalyst is synthesized by adopting the strategy of changing the roasting temperature, adding the additive for doping modification and changing the molar ratio of metal active components, the additive is combined with surface aluminum atoms, the framework strength is enhanced, pore channel collapse caused by acid / water erosion is reduced, the water resistance and acid resistance of the catalyst are improved, and the catalytic reaction activity is further improved. The catalyst disclosed by the invention is accurate and controllable in structure, can be synthesized in batches, and can be applied to the co-catalytic hydrogenation process of biomass pyrolytic oil and / or a model compound thereof and petroleum distillate oil and / or VR.

The invention provides high-activity contact type silver powder for photovoltaic conductive silver paste, a preparation method of the high-activity contact type silver powder and the photovoltaic conductive silver paste, and belongs to the technical field of photovoltaic materials. The high-activity contact type silver powder comprises net-shaped polycrystalline spherical silver powder and an active layer wrapping the surface of the net-shaped polycrystalline spherical silver powder. Wherein the reticular polycrystalline spherical silver powder is a spherical aggregate formed by stacking and self-assembling flaky particles with the particle size of 200-600 nm, and the reticular polycrystalline spherical silver powder is of a porous structure; and the active layer is an organic amine compound. The silver powder disclosed by the invention has good conductivity after being sintered, the adhesive force of a fine grid is relatively high, and the assembly has relatively high power output.

The invention discloses an MWW molecular sieve and a preparation method thereof, and the preparation method comprises the following steps: (a) mixing an alkali source, water, an aluminum source, a template agent and a silicon source to form a mixture A; (b) adding nano cellulose into the mixture A to form a mixture B, and pretreating, crystallizing and drying the mixture B to obtain the MWW molecular sieve. The preparation method disclosed by the invention is simple and convenient, easy to industrialize and wide in application prospect, and the MWW molecular sieve with the single-layer structure is prepared. The MWW molecular sieve with a single-layer structure can expose more active sites, promotes diffusion and mass transfer, shows excellent performance in many reaction processes, and particularly shows high activity and stability in a reaction with macromolecules as a substrate.

The invention discloses a lytic bacteriophage for preventing and controlling vibrio in an aquaculture environment. The bacteriophage vBValMR42H belongs to a muscle tail bacteriophage and is insensitive to chloroform, the capsid of the bacteriophage vBValMR42H is free of lipid substances, and the preservation number is GDMCC No: 67434-B1. The bacteriophage has the characteristics of high adsorption speed, short incubation period and high cracking amount, keeps high activity in a wide range of temperature (4-55 DEG C) and pH (2-11), and has strong environmental adaptability. Genome analysis shows that the bacteriophage does not contain virulence factors, antibiotic resistance genes and lyogen related genes, and is high in biological safety. Physical development analysis shows that the method can be divided into a new genus. The bacteriophage R42H has the advantages of high splitting efficiency, good environmental stability, strong specificity, gene safety and the like, and can be used as an ideal biological prevention and control agent for preventing and controlling vibrio alginolyticus diseases in aquaculture.

The invention relates to the technical field of pharmaceutical preparations, in particular to a multiple nano emulsion adjuvant and a preparation method thereof. The multiple nano emulsion adjuvant is prepared from 2.73 to 6.37 g of an oil phase matrix based on 100 g of a raw material system, 0.10 to 0.25 g of a sterol compound; 0.212 to 0.424 g of a nonionic surfactant; 0.00050 to 0.00200 g of a triterpenoid saponin type active adjuvant; 0.010 to 0.020 g of an anionic polymer modifier; 0.005 to 0.015 g of a cationic polymer modifier; 70-90 g of a buffer solution; the total mass of the raw materials is 100 g. The nano emulsion adjuvant prepared by the invention can be stored for 6 months at 2-8 DEG C under a low sterol condition, the particle size change does not exceed + 5%, no crystallization or layering is generated, and the stability of the active adjuvant is remarkably improved.

The invention discloses an environment-friendly and efficient composite metal oxide catalyst, a preparation method thereof and application of the catalyst in flue gas denitration. According to the catalyst, TiO2 serves as a carrier, and metal oxides such as Mn, Fe, W and Mo and various auxiliaries are loaded. The preparation method comprises the steps of dissolving, mixing, precipitating and the like, and process parameters of each step are accurately controlled. The catalyst is activated at the temperature of 50 DEG C, the NO conversion rate at the temperature of 120 DEG C is 96.3% or above, and the catalyst keeps high activity in a wide temperature range of 100-400 DEG C, resists SO2 toxicity, is environmentally friendly and non-toxic, is suitable for flue gas denitration of industrial boilers and the like, and has remarkable advantages compared with the prior art.

The invention discloses a preparation method and application of a mulberry leaf extract with high stability and high activity in a protein food system, and belongs to the field of food processing and nutrition and health. The mulberry leaf extract is prepared by taking mulberry leaves as a raw material through steam explosion and ball milling pretreatment, compound enzyme directional enzymolysis, ultrasonic-assisted extraction, protein-induced sedimentation combined with ultrafiltration membrane selective impurity removal, compound stabilization treatment and drying. The obtained extract is rich in 1-deoxynojirimycin (DNJ) and mulberry leaf polysaccharide, high-polymerization-degree polyphenol is remarkably removed, and high clarity and heat stability are achieved. The DNJ retention rate gt is obtained after the milk is stored at 37 DEG C for 7 days when the milk protein is applied to a milk system; and therefore, the product prepared by the method is obviously superior to the product prepared by the prior art. The extract is pure in flavor and high in biological activity, and can be widely applied to the field of healthy foods such as dairy products and protein beverages.

The invention belongs to the technical field of gene engineering, and particularly relates to a vitamin D3 hydroxylase mutant and application thereof in preparation of 25-hydroxyvitamin D3. According to the invention, the vitamin D3 hydroxylase Vdh-K1 is subjected to directed mutation, so that the vitamin D3 hydroxylase mutants VM, MV and VMV with higher activity are obtained. Compared with parent vitamin D3 hydroxylase Vdh-k1, the activities of the mutants VM, MV and VMV are respectively improved by 2.4 times, 1.6 times and 2.2 times, and when the mutant is used for preparing the 25-hydroxyvitamin D3, the conversion rate and the conversion rate of converting VD3 into the 25-hydroxyvitamin D3 are obviously improved.

The invention discloses a dihydrodaidzein reductase mutant and application of the dihydrodaidzein reductase mutant in synthesis of (3S, 4R)-tetrahydrodaidzein, and belongs to the technical field of biology. According to the mutant, wild-type dihydrodaidzein reductase DHDR is taken as a parent, single-point mutation or combined mutation is carried out, and a DHDR mutant is obtained; the parent site of the single point mutation is one of the 120th site, the 122nd site, the 170th site, the 178th site, the 214th site, the 219th site, the 220th site or the 220th site; the combined mutation adopts two modes: one mode is that a single-point mutation DHDR mutant is taken as a parent, mutation is carried out, and a combined mutation mutant I is obtained; and 2, taking the DHDR combined mutation mutant I as a parent, and performing mutation to obtain a combined mutation mutant II. The DHDR mutant disclosed by the invention is used for synthesizing (3S, 4R)-tetrahydrodaidzein by reducing dihydrodaidzein, and asymmetric reduction with high activity and high stereoselectivity can be realized.

The invention discloses a high-activity injectable self-healing temperature-sensitive hydrogel dressing and a preparation method and application thereof, the high-activity injectable self-healing temperature-sensitive hydrogel dressing is obtained by forming a temperature-sensitive hydrogel through a two-dimensional nano material MXene aqueous solution and F127 under the hydrogen-bond interaction, combining an M2 macrophage source exosome on MXene under the electrostatic adsorption action, and wrapping the MXene through a network structure of the hydrogel. The preparation method is simple, an obtained sample is free of organic solution residues, reaction conditions are mild, operation is convenient, the raw material cost is low, the hydrogel dressing has temperature-sensitive, injectable and self-healing performance, the hydrogel dressing has temperature-sensitive and injectable performance, is sol at normal temperature, forms gel after making contact with skin and is convenient to smear and use on wounds, and experimental results prove that the hydrogel dressing has good application prospects. The hydrogel has good biocompatibility and relatively strong antibacterial performance, and can effectively play anti-inflammatory and vascular regeneration promoting roles in diabetic wounds and promote rapid repair of the diabetic wounds.

The invention relates to the technical field of coating materials, and discloses a pure titanium micro-arc oxidation coating for a vacuum cup and a preparation method thereof.The preparation method comprises the following steps that surface pretreatment is conducted, specifically, a pure titanium vacuum cup inner container workpiece is sequentially subjected to degreasing, acid pickling and ultrasonic cleaning; preparing an electrolyte, namely adding 15-25 parts by weight of a silicon-containing compound, 5-12 parts by weight of metal salt, 3-8 parts by weight of an antibacterial agent and 1-5 parts by weight of a stabilizer into deionized water, and controlling the pH value to be 8.5-10.5; and performing micro-arc oxidation treatment. According to the invention, a silane compound in the micro-arc oxidation electrolyte contains a high-activity silanol group which is subjected to condensation reaction with titanium hydroxyl on the surface of a pure titanium substrate under the action of an electric field to form stable covalent bonding, so that the bonding strength of the coating and the substrate is enhanced; metal ions generated by metal salt electrolysis are co-deposited with titanium ions through plasma discharge, a composite oxide structure is constructed, and micro defects on the surface of a titanium substrate are sealed.

The invention discloses two mycobacterium bacteriophages and application thereof. The two bacteriophages both have a splitting spectrum width and efficient splitting capability, can specifically realize effective splitting of mycobacteria of five specific sequence types, and are further applied to the field of prevention and control of mycobacteria. Specifically, the bacteriophage MP2435 and the bacteriophage MP2451 not only can effectively inhibit the proliferation process of mycobacteria and block the formation of a biofilm of the mycobacteria, but also can efficiently kill the mycobacteria in a milk matrix; meanwhile, the two bacteriophages can still keep relatively high activity under the conditions that the temperature is 37-65 DEG C and the pH value is 3-12, and the bactericidal activity of the bacteriophages can be stably maintained even in acid-base, high-temperature and ultraviolet-containing extreme environments. Through the characteristics, the application scene and application range of the bacteriophage in mycobacterium prevention and control are remarkably widened, and an efficient and stable novel technical means is provided for biological prevention and control of mycobacterium.

This invention relates to a method for using a low-content ruthenium-based catalyst modified with nitrogen and oxygen ligands in the hydrochlorination of acetylene. The invention utilizes 2-pyridine carboxylate as a ligand, commercial activated carbon as a support, trace amounts of ruthenium as the main active component, and water as a solvent. An improved synthesis procedure yields a low-content ruthenium-based catalyst with ruthenium ions coordinated by a modifier and commercial activated carbon as a support, significantly improving catalyst performance while reducing ruthenium content. This catalyst exhibits high activity and vinyl chloride selectivity in the fixed-bed hydrochlorination of acetylene to vinyl chloride, and its low cost makes it highly valuable for industrial applications. The ruthenium loading is 0.1%, and the reaction gas space velocity is 170 h⁻¹. ‑1 V (C2H2) / V (HCl) With a ratio of 1:1.05 and a reaction temperature of 180℃, the acetylene conversion rate can reach 84.3%, the vinyl chloride selectivity is greater than 99%, and the activity remains basically unchanged within 10 hours.

The invention belongs to the field of preparation of nano materials, and discloses a CoP / Co (OH) 2 sea urchin-shaped heterojunction catalyst growing on foamed nickel and a preparation method and application of the CoP / Co (OH) 2 sea urchin-shaped heterojunction catalyst. Alkali cobalt carbonate (CoCH) is used as a precursor, a crystalline phase CoP substrate is generated through a low-temperature phosphating method, then the surface of the crystalline phase CoP substrate is uniformly coated with an amorphous Co (OH) 2 layer through an electro-deposition process, and the self-supporting phosphating / hydroxyl heterogeneous structure catalyst (CoP / Co (OH) 2) is successfully constructed. The obtained CoP / Co (OH) 2 shows excellent complete water splitting performance, and is benefited from the high-activity specific surface area (Cdl = 44.66 mF cm <-2 >) and the interface rapid electron conduction characteristic (Rct = 0.43 omega) of a heterogeneous structure; when two electrodes are assembled to fully decompose water, the cell voltage is only 1.780 V when the current density is 250 mA cm <-2 >, and after continuous operation is carried out for 24 hours, the performance is basically kept unchanged, and the voltage fluctuation ratio is lower than 0.5%. CoP / Co (OH) 2 is prepared into a 2 * 2cm < 2 > self-supporting electrode to construct AEMWE, only 2.08 V cell voltage is needed under the ultrahigh current density of 1A cm <-2 >, the AEMWE can stably run for 250 hours, the attenuation rate is 80 mu V h <-1 >, meanwhile, the hydrogen production efficiency is calculated to reach 96.2% through gas metering and Faraday law, and the engineering potential of the AEMWE in large-scale hydrogen production application is verified.

The invention provides a high-activity chitinase mutant and application thereof in degradation of crustacean waste, and belongs to the technical field of enzyme engineering and agricultural waste conversion. According to the invention, chitinase PbChi from Paenibacillus barengltzii is subjected to molecular modification, and a plurality of chitinase mutants with high activity are successfully constructed by increasing the flexibility of a connexin, changing steric hindrance at a substrate catalytic crack inlet and changing catalytic residues in a beta sheet layer in a catalytic structural domain through calculation design and experimental verification; the chitinase mutant can effectively degrade shrimp shell meal, so that carapace waste is effectively utilized, and the chitinase mutant has a wide application prospect in the biological feed industry.

The invention relates to a low-temperature preparation method of a high-activity chelated zinc fertilizer, and belongs to the technical field of fertilizer chemical industry. Aiming at the problems of chelate decomposition and high energy consumption caused by an existing high-temperature process, ethylene diamine tetraacetic acid is added step by step in a low-temperature environment of 35-45 DEG C: firstly, an initial chelating solution is formed by adding 0.8-1.0 time of theoretical chelating molar weight, and then a sodium hydroxide solution is dropwise added to control the pH to be 3.5-4.5 within 60-120 minutes and is stable; and then supplementing ethylenediaminetetraacetic acid which is 0.1-0.2 time of the theoretical amount, reacting for 60-120 minutes to achieve chelation balance, and finally stirring, aging and naturally cooling. The method obviously improves the chelating efficiency and the product stability, reduces the energy consumption, and is used for preparing the efficient and stable liquid zinc fertilizer.

The application discloses a preparation method of a catalyst for liquid-phase refining of crude octanol, and the preparation method comprises the following steps: (1) mixing pretreated fly ash and pseudo-boehmite, adding deionized water and nitric acid, stirring until a colloid is formed, drying the colloid, mixing the dried colloid with kaolin, and obtaining a carrier through kneading, extrusion molding, drying and calcination; (2) taking a nickel salt, a manganese salt and a zinc salt as active components, taking a calcium salt as an auxiliary component, dissolving the active components and the auxiliary component in deionized water to obtain a salt solution, adding n-hexane into the salt solution and stirring uniformly to prepare an impregnation solution, immersing the carrier in the impregnation solution, and obtaining the catalyst through washing, drying and calcination. The catalyst prepared by the method is mainly used in a liquid-phase refining reaction process of crude octanol, and has high activity stability and selectivity.

The invention discloses a preparation method and application of a high-valence nickel monatomic catalyst, through the synergistic effect of nickel-phenanthroline complexing and inert template anchoring, dense and stable anchoring sites are provided for nickel atoms, atom migration and agglomeration in the high-temperature pyrolysis process are effectively inhibited, and the high-valence nickel monatomic catalyst is prepared. Meanwhile, by combining with an air-inert atmosphere two-step calcination procedure, air pre-oxidation is carried out, and a nickel precursor is stabilized in a carrier framework to prevent the nickel precursor from being reduced into a metal state in subsequent high-temperature inert calcination, so that the nickel precursor is locked in an electron-deficient high valence state, and a nickel-loaded material with the nickel loading capacity of 2.9-9.2 wt% and the nickel loading capacity of 9.2-9.2 wt% is prepared. And the nickel element stably exists mainly in the form of Ni < 3 + > or a higher-valence monatomic form, so that the three-in-one breakthrough of high load, high valence and high stability is realized. When the obtained catalyst activates persulfate, high-valence metal oxygen species are preferentially generated, various new pollutants are degraded, and the catalyst has high activity, selectivity and high stability.

The invention discloses a high-efficiency aerobic fermentation corncob-based biological conditioner and application thereof. Aiming at the common problems of unstable carrier effect, poor environmental adaptability, easiness in inactivation of the microbial inoculum, difficulty in continuously exerting efficacy and the like existing in the existing composting microbial inoculum, the agricultural waste corncob with a porous structure and excellent water-retaining and fertilizer-retaining natural characteristics is pretreated and modified; and the immobilized carrier of the aerobic fermentation inoculant with high activity and high stability is constructed. The carrier matrix can be used for efficiently loading and remarkably improving the expanding culture core aerobic fermentation functional flora to prepare a solid biological conditioner. The corncob-based biological conditioner is applied to the composting process of organic solid wastes, promotes the humification process of organic materials, shortens the composting period, improves the fermentation efficiency of the materials, and effectively improves the resource utilization level of the organic solid wastes.

The invention discloses a high-strength and high-toughness lignin-based liquid crystal elastomer as well as a preparation method and application thereof. A liquid crystal unit is subjected to hydroxyl end-capping modification and then reacts with a high-activity chain extender isocyanate to prepare a liquid crystal-polyurethane prepolymer, and finally the liquid crystal-polyurethane prepolymer is crosslinked with low-molecular-weight lignin, so that the lignin-based liquid crystal elastomer is prepared through a one-pot two-step method. According to the invention, a preparation system of a conventional liquid crystal elastomer by utilizing Michael addition polymerization is changed, a natural microphase separation structure and a strong intermolecular interaction force of polyurethane are utilized, and meanwhile, lignin with good compatibility with a liquid crystal unit is introduced as a covalent cross-linking agent, so that the mechanical properties of the liquid crystal elastomer are greatly improved. The prepared lignin-based liquid crystal elastomer is high in strength and toughness, can be repeatedly processed and utilized, has an ultraviolet aging resistance function and a shape memory function, and overcomes the problem that a traditional liquid crystal elastomer is poor in mechanical property.

The invention discloses PDRN and a preparation method and application thereof.The base sequence of the PDRN is shown as SEQ ID NO1, and the preparation method of the PDRN comprises the following steps that fermentation treatment is conducted through lactobacillus plantarum, and thalli are collected after an obtained fermentation culture solution is centrifuged; and resuspending the obtained thalli, homogenizing and crushing, centrifuging to remove precipitate, concentrating by using a 5kDa hollow fiber membrane, purifying the obtained concentrated solution by using a Q column, and then concentrating and changing the solution to obtain the high-purity PDRN. According to the method, the PDRN is obtained through fermentation of lactobacillus plantarum for the first time, compared with PDRN sourced from salmon or salmon and the like at present, the method is lower in production cost, and a new way is provided for PDRN production. The PDRN obtained by the method disclosed by the invention is high in purity and single in molecular weight, and experiments prove that the PDRN obtained by the method disclosed by the invention has higher activity in the aspects of promoting cell proliferation, promoting collagen generation and the like.

The invention provides a laser crystal heterogeneous bonding method and an optical element, and relates to the technical field of laser, and the method comprises the steps: carrying out the ultra-precise surface treatment of the to-be-bonded surfaces of a laser crystal and a heterogeneous material based on the laser crystal and the heterogeneous material; respectively depositing at least one transition layer on the two to-be-bonded surfaces after surface treatment through a physical or chemical deposition method; the outermost layers of the two transition layers are made of the same material; carrying out ion beam activation treatment on the two surfaces to be bonded on which the transition layers are deposited so as to form high-activity surfaces; and aligning the two activated surfaces to be bonded in a vacuum environment at room temperature and applying pressure, and realizing room-temperature bonding through electrostatic force and chemical bond action to obtain a bonding body of the laser crystal and the heterogeneous material. According to the invention, thermal-mechanical property and chemical property differences among heterogeneous materials are overcome, and high-strength, low-stress and high-optical-quality bonding is realized.

The invention discloses an internal-acid and external-alkali type organic-inorganic hybrid molecular sieve catalyst as well as a preparation method and application thereof, and belongs to the technical field of heterogeneous catalytic materials and chemical processes. According to the catalyst, a hydrogen type Beta molecular sieve is used as an acidic inner core, polyvinylpyrrolidone (PVP) is used as an organic shell, and a unique inner-acid outer-alkali structure is formed. The preparation method comprises the following steps: hydrothermally synthesizing a hydrogen type Beta molecular sieve with a specific silica-alumina ratio, and then coating PVP through surface adsorption. The catalyst is used for catalyzing the condensation of methylal and trioxymethylene under mild conditions (40-70 DEG C and normal pressure) to prepare polyoxymethylene dimethyl ethers (DMMn). The PVP shell covers acidic sites on the outer surface of the molecular sieve to form an external neutral / weak base and internal strong acid microenvironment, so that the secondary side reaction of the product is effectively inhibited, the trioxymethylene conversion rate of more than 98% and the DMMn selectivity of more than 96% can be obtained in the reaction at 50 DEG C and normal pressure, the product distribution can be regulated and controlled, and the traditional Anderson-Schulz-Flory distribution limitation is broken through. The catalyst disclosed by the invention has the advantages of high activity, high selectivity, mild conditions and easiness in separation, and has a good industrial application prospect.

The invention discloses a 7alpha-hydroxysteroid dehydrogenase mutant with improved catalytic activity as well as a coding gene and application thereof, and the amino acid sequence of the 7alpha-hydroxysteroid dehydrogenase mutant is obtained by mutation at one or more sites of the 120th site, the 195th site and the 207th site on the basis of the amino acid sequence shown in SEQ ID NO: 1. According to the 7alpha-HSDH mutant disclosed by the invention, the key site of the 7alpha-HSDH enzyme is modified, so that the mutant with higher activity than that of a wild enzyme is obtained, the efficiency bottleneck in UDCA biosynthesis is effectively broken through, and an efficient and green enzyme catalyst is provided for industrial application.