172 results about "Secondary growth" patented technology

A seed coating composition is disclosed. The seed coating composition has a first protective polymer film coating, which is non-phytotoxic, maintains oxygen exchange properties, and is hygroscopic. The seed coating composition also has a secondary growth augmentation coating. Also disclosed is a method for coating seeds with a first protective polymer film coating and a secondary growth augmentation coating.

A catalyst for an integrated supported carbon modular sieve comprises an integrated beehive cordierite, a carbon-nano tube and an HZSM-5 modular sieve, wherein the carbon-nano tube takes 7-20 proportions, HZSM-5 takes 10-30 proportions, and cordierite tales 60-80 proportions. The preparation method is that: carbon-nano tube is produced in situ on the integrated beehive cordierite by using chemical vapor deposition firstly, and the carbon-nano tube is taken as carrier, then the ZSM-5 modular sieve is developed on the carrier by using a secondary growth method. The catalyst for an integrated supported carbon-modular sieve can be used for the gas-phase synthesis of dimethyl ether DME by the dehydration of methanol.

The invention relates to a core-shell type aromatic conversion catalyst, a preparation method and application thereof, mainly solving the problems of strong acidity of an outside surface, rapid inactivation speed and low selectivity of aromatic shape selective catalysis in previous molecular sieve based catalysts. The invention adopts the following technical scheme: the preparation method that ZSM-5 crystal grain is taken as a core and a high silicon MF1 molecular sieve shell layer is formed on the outside surface of the core crystal by secondary growth is used for synthesizing the core-shell type zeolite molecular sieve with tightly-bonded core and shell and communicated pore canals, then the catalyst is prepared by shaping and baking 10-100% of core-shell type zeolite molecular sieves and the balance binder in terms of weight percent to better solve the above problems. The invention can be used in industrial production of aromatic conversion reactions of toluene disproportionation, toluene methylation, xylene isomerisation, trimethylbenzene cracking, cumin cracking and styralyl alcohol alkylating.

The invention discloses a longitudinally-conductive GaN (gallium nitride) normally-closed MISFET (metal integrated semiconductor field effect transistor) device and a manufacturing method thereof. The device successively comprises a substrate (1), an n-type GaN layer (2), an electronic barrier layer (3), a non-doped GaN layer (4) and a heterostructure potential barrier layer (5) from bottom to top, wherein a groove is etched in the n-type GaN layer from the surface of the heterostructure potential barrier layer; a p-type GaN layer is formed on the groove by secondary growth so as to realize a grid conducting channel (7); two ends of the heterostructure potential barrier layer form source electrodes (9); an insulating layer (8) is covered on the grid conducting channel and the exposed surface of the heterostructure potential barrier layer; a grid electrode (11) is covered at a channel position on the insulating layer; and drain electrodes (10) are covered on the underside of the substrate. In the invention, a two-dimensional electron gas heterostructure with high concentration is taken as an access area, thus effectively reducing the on resistance; and the thin p-type GaN layer is formed in the etching groove by secondary growth, thus being easy to improve the threshold voltage and channel mobility of the longitudinally-conductive normally-closed MISFET.

The invention relates to a preparation method of an all-silicon MFI type molecular sieve membrane with high stability. The preparation method comprises the following steps: in a neutral synthetic liquid, preparing an MFI molecular sieve seed crystal and an MFI molecular sieve membrane by using villiaumite as a mineralizer and tetrapropylammonium bromide as a template agent under a neutral synthesis condition; crushing the MFI molecular sieve seed crystal by high-energy ball milling and then applying the crushed seed crystal to the surface of a porous support body; and preparing an MFI zeolite molecular sieve membrane by secondary growth. Compared with the MFI type molecular sieve membrane synthesized from an alkali system, the fluorine-containing MFI type molecular sieve membrane prepared by the method shows good stability in the process of removing ethanol from an ethanol/water mixture by pervaporation and has an excellent industrial application prospect.

The invention discloses a graphene single crystal and a rapid growth method thereof. The rapid growth method comprises carrying out primary passivation on annealed copper foil, orderly carrying out primary growth, secondary passivation and secondary growth at a constant temperature, and carrying out cooling to a room temperature so that crystal growth is stopped and the graphene single crystals are deposited on the copper foil, wherein in primary growth and secondary growth, growth gas comprises reduction gas and carbon source gas, and in secondary growth, the partial pressure of the carbon source gas in the growth gas is higher than that of the carbon source gas in the primary growth. The rapid growth method has simple processes and can be industrialized. The graphene single crystal has single crystal domain area size in a subcentimeter level and high single crystal quality and can be used in electronics.

The invention relates to a preparation method of an orientation LTL type molecular sieving membrane for gas separation. The preparation method comprises the following steps: (1) mixing an alkali source, an aluminum source, a silicon source and deionized water to obtain gel and performing hydrothermal crystallization for preparing a seed crystal; (2) performing acidic treatment on the seed crystal prepared in the step (1) so as to remove aluminum from the grain surface, and then preparing a suspension in sec-butyl alcohol, and stirring for modifying; (3) dropwise adding the LTL type molecular sieving suspension acquired by modifying in the step (2) into an LB liquid tank for forming a membrane, and then transferring the acquired membrane onto the surface of a carrier; (4) mixing an alkali source, an aluminum source, a silicon source and deionized water to obtain a secondary growth synthetic solution; (5) contacting the product from the step (3) with the secondary growth synthetic solution from the step (4), performing hydrothermal crystallization and acquiring the LTL type molecular sieving membrane on the carrier. According to by the invention, the simple, controllable, efficient and repeatable LB method is adopted for preparing the orientation LTL type molecular sieve seed crystal layer and the high c-axis orientation LTL type molecular sieving membrane is prepared through secondary growth; the operation is simple, the degree of orientation is easily controlled, and the repeatability is high.

The invention provides a method for preparing high-performance fluorine-containing mordenite zeolite membrane. The method is characterized in that crystallization is performed for 5 to 30 hours at a synthesis temperature between 130 and 190 DEG C by a secondary growth method so as to form a layer of dense defect-free fluorine-containing mordenite zeolite membrane on the outer surface of a porous tubular supporting body; the molar ratios of synthesis materials are as follow: the molar ratio of SiO2 to Al2O3 is 10 to 60; the molar ratio of H2O to SiO2 is 15 to 60; the molar ratio of Na2O to SiO2 is 0.15 to 0.5; and the molar ratio of F- to SiO2 is 0.01 to 2. NaF, KF, AlF3, (NH4) SiF6 and NH4F and the like can be used as a fluoride source. The preparation method avoids adding expensive organic template agents, and the fluoride source added greatly improves the permeability and acid resistance of the membrane. For example, when the method is applied to permeation experiment on water/ethanol (10/90 percent by weight) system at 75 DEG C, the average water permeation flux J is 1.2 to 2.5 kg/m2 h; the separation factor (alpha) is more than 1,000; and the synthesized membrane still maintains good stability in acid solution with a pH of less than 1. The method has the advantages of simple novel process, good repeatability and suitability for industrial production.

The invention discloses a method for synthesizing silicalite-1 zeolite membranes. The method comprises: preparing synthetic fluid of crystal seeds, performing hydrothermal synthesis for 0.5 to 3 days, obtaining crystal seeds uniform in particle size and preparing a crystal-seed solution; impregnating a carrier with the crystal-seed solution for 5 to 10 seconds, drying and roasting the obtained product; preparing template-free zeolite membrane mother liquor, placing diaphragms containing crystal-seed layers in the mother liquor and performing hydrothermal reaction in a reaction kettle for 4 to 8 hours; and washing and drying membranes. As the synthetic fluid has no template, roasting is not needed after secondary growth, so that defect-free pure silicon zeolite membranes can be obtained. The zeolite membranes are resistant to heat and chemicals, have good stability, and can be applied to the permeation and separation of gas and liquid steam at high temperature and other aspects.

The invention relates to a method for preparing a metal organic frameworks (MOFs) membrane on the surface of a polytetrafluoroethylene hollow fiber carrier. A continuous crackless MOFs membrane is prepared on the surface of a polytetrafluoroethylene hollow fiber membrane through a method of ''seed precoating-heat treatment-secondary growth''. The method is characterized in that after seed precoating, seeds and the polytetrafluoroethylene carrier are effectively combined through the heat treatment method so as to induce to generate the continuous MOFs membrane. The method of the invention has certain universality, is simple to operate, and is easy to control.

The invention discloses a method for preparing microbial oil. The method comprises the following steps of: performing aerated culturing on a carbon source which contains glucose and xylose and serves as a raw material to obtain a leavening; and extracting the microbial oil from the leavening. According to the method, glucose and xylose in a culture medium can be transformed synchronously, so that the inhibition function of the glucose on the utilization of other substrates during the utilization of mixed sugar is relieved, the phenomenon of secondary growth in the process is avoided, the substrate transformation rate is high, and the production cost can be lowered remarkably. The method has a great application prospect in the aspect of the production of microbial oil with a lignocellulose material.

The invention discloses a method for preparing a highly-oriented MFI-type molecular sieve membrane by a secondary growth process, which comprises the following steps: 1) preparation of a secondary growth synthesis liquid: mixing certain amounts of ethyl orthosilicate, tetrapropyl ammonium hydroxide and water, stirring at room temperature for 3-5 hours, adding an ammonium salt water solution with a certain concentration into the clear synthesis liquid, and continuing stirring for 1-3 hours to obtain the final synthesis liquid, wherein the synthesis liquid is composed of the following components in parts by mole: 1 part of ethyl orthosilicate, 0.1-0.4 part of tetrapropyl ammonium hydroxide, 100-500 parts of water and 0.075-0.3 part of water; 2) putting a carrier coated with a b-axis-oriented crystal seed layer into a high-pressure synthesis kettle, pouring the synthesis liquid, and sealing; crystallizing at 120-180 DEG C for 3-12 hours; and 3) cooling the synthesis kettle, taking out the carrier, washing and drying to obtain the oriented MFI-type molecular sieve membrane on the carrier. The ammonium salt added into the traditional synthesis liquid can effectively inhibit the twin crystal from generation in the secondary growth process. The method is simple to operate, and has the advantages of wide application range, no special requirements for the carrier and low preparation cost.

The invention provides a preparation method of a fluorine-containing MFI zeolite membrane, which is characterized by comprising an ultra-thin synthetic liquid containing fluoride (MF), wherein the molar ratio is 1SiO2: 0.05-1.5MF: 0.05-0.5TPABr: 0.05-0.5TPAOH: 200-2000H2O, and a layer of continuous dense fluorine-containing MFI zeolite membrane is formed on the surface of a porous tubular supporting body coated with fluorine-containing MFI zeolite crystal seeds by using a secondary growth hydrothermal method. The pervaporation test is carried out for the prepared MFI zeolite membrane in an ethanol / water (5/95wt%) system at the temperature of 60 DEG , and the permeation flux and the separation factor can be respectively up to 2.85kg/m2. h and 68. The method has mild conditions of preparation process, and simple and fast operation step, and greatly reduces the contents of a silicon source and a template agent in the synthetic liquid, thereby greatly reducing the preparation cost of the membrane, and obviously improving the permeability of the MFI zeolite membrane; and the fluorine-containing MFI zeolite membrane has wide application prospects in the fields of the separation of liquid such as organic matter / water mixture, gas separation, membrane reactors and the like.

The invention discloses a method of preparing a high-oriented MFI type zeolite membrane by virtue of secondary growth under the neutral condition. The method comprises the following steps: 1) preparing a neutral synthetic fluid, wherein the synthetic fluid is prepared from the following components including a silica source, tetrapropylammonium bromide and water, and the molar ratio of the silica source to tetrapropylammonium bromide to water is 1 to (0.1-5) to (10-2000); and 2) stirring the synthetic fluid for 10-60 minutes at room temperature, charging into a reaction kettle, putting a supporting body coated with a b axis oriented crystal seed layer into the reaction kettle, immersing the supporting body with the synthetic fluid, sealing the reaction kettle, carrying out heating synthesis, washing, and drying to obtain the oriented MFI type zeolite membrane on the supporting body, wherein the synthesis temperature is 120-200 DEG C, and the synthesis time is 12-72h. According to the method disclosed by the invention, the synthesized MFI type zeolite membrane has high b axis orientation, the used synthetic fluid is neutral and is small in damage on the surface of the supporting body and low in raw material cost, and the cost is easily lowered.

The invention provides a preparation method of a molecular sieve membrane. The preparation method comprises the following steps: firstly, preparing a crystal seed layer by virtue of a dynamic wetting method; secondly, preparing the molecular sieve membrane by virtue of a secondary growth method; and thirdly, activating the molecular sieve membrane. Compared with the traditional secondary growth method, according to the preparation method, the crystal seed layer is coated by virtue of the dynamic wetting method instead of the traditional dip-coating method so as to improve the coating method of the crystal seed layer, and by the spreading wetting principle of a solid-liquid interface and adopting alcohol having low surface tension as a dispersion liquid, the crystal seeds are uniformly dispersed in defects on the surface of a carrier; the molecular sieve membrane is then prepared by virtue of the secondary growth method; the molecular sieve membrane is moderately activated so that the molecular sieve membrane can maintain intact denseness and has good repeatability and high success rate and is suitable for industrial amplification application.

The invention provides a mechanical ship for treating aquatic plants in a river channel. The ship comprises a ship body, a multi-purpose rolling knife, a conveying belt, a grinding device, a slag pressing device, a power device and a filter screen, wherein the multi-purpose rolling knife is arranged at one end of the ship body; the conveying belt, the grinding device and the slag pressing device are arranged in a direction from the multi-purpose rolling knife to the ship body in turn and are driven by the power device; and the filter screen is arranged at the slag outlet of the slag pressing device. The ship reduces the labor intensity of manual salvage, solves the provenance problem of secondary growth of the aquatic plants, reduces the unsafe factor of manual salvage in the river channel, and can comprehensively utilize aquatic plant slag.

The invention relates to a method for manufacturing an enhanced type AlGaN/GaN/ field effect transistor, namely a method for manufacturing AlGaN/GaN HFET by adopting a secondary growth AlGaN layer. The method comprises the following steps: firstly, a buffer layer grows on a substrate firstly, and a GaN epitaxial layer grows on the buffer layer; secondly, a first AlGaN layer grows on the GaN epitaxial layer to accomplish the first material growth; thirdly, a SiO2 mask membrane is deposited on the first AlGaN layer, and the SiO2 mask membrane formed on a grid zone is reserved through the photoetching method; fourthly, a second AlGaN layer grows on the unmasked first AlGaN layer to accomplish the second material growth; fifthly, the SiO2 mask membrane is removed; sixthly, a source electrode and a drain electrode are formed on the second AlGaN layer, and then a grid electrode is formed on the grid zone. Moreover, the invention also discloses the enhanced type AlGaN/GaN/ field effect transistor. The method has the advantages of simple process and good reliability, and can obtain higher threshold voltage and transconductance.

The invention discloses a growth method of a non-polar m-surface GaN film based on a gamma-surface LiAlO2 substrate, which mainly solves the problem of poor quality of the conventional non-polar m-surface GaN materials. The method comprises the following processing steps: (1) putting the gamma-surface LiAlO2 substrate into an MOCVD reaction chamber, and carrying out heat treatment on the substrate; (2) growing a low-temperature AlN nucleating layer with the thickness of 30-100nm and the temperature of 500-600 DEG C on the gamma-surface LiAlO2 substrate; (3) growing a high-temperature AlN layer with the thickness of 60-200nm and the temperature of 900-1050 DEG C on the low-temperature AlN nucleating layer; (4) growing an m-surface GaN buffer layer with the thickness of 1000-5000nm and the temperature of 900-1050 DEG C on the high-temperature AlN layer; (5) taking the substrate after the growth processes out of the reaction chamber, and corroding the substrate for 1-5 minutes in the molten KOH solution to form a transverse epitaxial region; and (6) putting the corroded substrate into the MOCVD reaction chamber, and carrying out secondary growth to form a non-polar m-surface GaN epitaxial layer with the thickness of 2000-5000nm and the temperature of 1000-1100 DEG C. The invention has the advantages of few defects and smooth surfaces and can be used for manufacturing m-surface GaN-based light-emitting diodes.

The invention specifically relates to a coordination polymer membrane material, a preparation method for the same and application of the same in separation of mixed gas or chiral isomers, belonging to the field of membrane materials and separation technology thereof. The referred coordination polymer Ni2(L-asp)2bpy membrane material is a three-dimensional porous material which is formed by coordination between metallic nickel ions and L-aspartic acid (L-asp) and 4,4-bipyridine (bpy) and has a uniform pore channel size, wherein metallic nickel coordinates with oxygen atoms of L-aspartic acid to form a layer which is then propped up by a nitrogen atom coordination column in 4,4-bipyridine to form a three-dimensional skeleton structure. According to the invention, through selection of different carriers and carrier pretreatment methods, the coordination polymer membrane material is prepared by using an in situ or secondary growth method under different solvothermal conditions. Results show that the membrane material provided in the invention has a good separation effect on mixed gas or chiral isomers.

The invention provides a method for detecting Escherichia coli in milk based on an ultraviolet-visible spectrum technology. Under the complex background environment similar to that of the milk, the problems that detection spectra of microorganisms are affected by unfavorable factors, the phenomena of characteristic wavelength red shift, obvious noise and the like are generated, consequently spectral characteristics are difficult to pick up, and the accuracy of quantitative detection results is low can be effectively solved. The method comprises the steps that firstly, Escherichia coli powder is activated and subcultured, and a to-be-detected bacterium suspension is prepared; an ultraviolet spectrophotometer obtains ultraviolet-visible spectra of the to-be-detected bacterium suspension at different culture times; noise interference is eliminated through a standard normal correction method and an S-G convolution smoothing method; the spectral characteristic red shift phenomenon is explained from the angle of a formation mechanism of a benzene ring conjugated structure, and thus the characteristic waveband range is determined; the characteristic wavelengths are picked up in the characteristic waveband through a continuous projection algorithm, and the characteristic wavelengths are effectively screened according to the secondary growth law of the microorganisms; and the model relationship between the characteristic wavelengths and the total number of the microorganisms is established through a partial least squares method, and the total number of the Escherichia coli in the milk is quantitatively analyzed

The invention relates to a 3D rock mass point cloud registration method based on plane polygon matching. The method mainly comprises three stages (1), plane detection based on voxel multi-time regiongrowth; (2), PCA-based polygon matching; and (3), point cloud registration based on matching point pairs. The method comprises the following steps: firstly, dividing initial rock mass point cloud intovoxel grids, and extracting reliable growth units in each voxel by utilizing an area growth algorithm; Performing secondary growth based on the growth unit to obtain an initial plane set; for the initial plane set, remaining point clouds in neighborhoods around each plane grow, and a plane set in the rock mass point clouds is extracted; Secondly, extracting a polygon boundary of the plane point cloud, projecting a polygon to a two-dimensional plane by utilizing PCA, and carrying out polygon matching; the rock mass point cloud registration method based on the ICP algorithm is suitable for theregistration process of large-scene rock laser scanning point cloud, and the rock mass point cloud registration can be efficiently and accurately achieved.