86 results about "Hydrolytic Process" patented technology

Present invention teaches the method of using a keratin hydrolysis peptide (“KHP”) solution to promote the growth of cotton under low light conditions. By selectively choosing specific weights of feathers and water, and treating the mixture to a high-temperature high-pressure hydrolysis process, the resulting solution is confirmed to contain at least 253 peptides and then apply to the cotton by leaf spray at seeding stage. Optionally, the KHP solution can be diluted by water, as disclosed in the specification, for infusing or leaf spraying.

Present invention teaches the method of using a keratin hydrolysis peptide (“KHP”) solution to improve the efficacy of fertilizer usage and absorption by soybeans. By selectively choosing specific weights of feathers and water, and treating the mixture to a high-temperature high-pressure hydrolysis process, the resulting solution is confirmed to contain at least 253 peptides and then infused to the fertilized soil in which the soybean seeds are grown, as well as the plants after the seed start sprouting. Optionally, the KHP solution can be diluted by water, as disclosed in the specification, for applying to the soil around the soybean.

The invention discloses a method for preparing superfine high-purity germanium dioxide from germanium tetrachloride. The method comprises the following steps: step 1, preparing a reactor; step 2, preparing hydrolysis mother liquor; step 3, hydrolysis; step 4, suction filtration and washing; step 5, drying; and step 6, screening. According to the method for preparing the superfine high-purity germanium dioxide, the production efficiency of the superfine high-purity germanium dioxide can be effectively improved, and the superfine high-purity germanium dioxide is efficiently prepared by controlling the hydrolysis ratio, the acidity of hydrolysate, the germanium content, the temperature of the whole hydrolysis process, the hydrolysis rate and the stirring power.

The invention discloses an AI (artificial intelligence)-based clindamycin phosphate processing hydrolysis optimization method and an AI-based clindamycin phosphate processing hydrolysis optimization system. According to the method, a reaction process prediction model capable of representing a process bifurcation phenomenon and fusing a chemical reaction mechanism and process data is constructed, and the model is utilized to train a multi-target decision-making agent. In the training process, causal relationship analysis is utilized to guide exploration of the intelligent agent, dynamic security constraints based on a chemical mechanism are introduced, and finally a strategy set covering the Pareto optimal frontier is generated. An operator can select a strategy according to production requirements, and closed-loop self-adaptive control is carried out by the system. The method aims to solve the problem of multi-target dynamic optimization caused by process bifurcation in the hydrolysis process, balance of multiple conflict targets such as yield, impurities and energy consumption is achieved by actively controlling the process bifurcation, and the robustness, safety and stability of the process are improved.

The invention relates to the technical field of oil field filtrate loss reducers, in particular to a hydrolyzed polyacrylonitrile salt copolymer and a preparation method thereof.The hydrolyzed polyacrylonitrile salt copolymer is prepared from, by weight, 15-20 parts of composite slurry, 5-8 parts of modified chitosan, 0.1-0.12 part of ethylenediaminetetraacetic acid and 0.12-0.15 part of zinc acetate through an oxidative degradation system; the hydrolysis process of polyacrylonitrile is improved to form a small molecular structure, the small molecular structure is compounded with modified chitosan with a grafted chain segment, and a copolymer is formed through covalent and non-covalent interaction, so that the filtration loss reduction performance of the polyacrylonitrile under high-temperature and high-salt conditions is improved.

The invention discloses a method and a system for recycling a pole piece of a waste power battery, an adhesive of the pole piece is hydrolyzed by adopting a water vapor environment, the hydrolysis process is accelerated by utilizing the high temperature of water vapor, and no condensed water participates in the whole process, so that black powder and a current collector are prevented from forming adhesion and forming relatively pure separation, and meanwhile, the recovery rate of the pole piece of the waste power battery is greatly improved. Separation is formed by a screening means in the absence of condensed water, so that the current collector and the black powder are thoroughly separated and are relatively clean; therefore, when the process method is used for sorting the black powder of the pole piece and the current collector, the problem of excessive impurities is avoided, the working efficiency is improved, the energy consumption is reduced, the water consumption is reduced, and the treatment cost is saved.

Present invention teaches the method of using a keratin hydrolysis peptide (“KHP”) solution to improve the growth of various farming plants exposed to acidity stress by selectively choosing specific weights of feathers and water, and treating the mixture to a high-temperature high-pressure hydrolysis process, the resulting solution is confirmed to contain at least 253 peptides and then infused to the soil or other growth medium. Optionally, the KHP solution can be diluted by water, as disclosed in the specification, for applying to the soil or other growth medium.

The invention discloses a synthesis method of 5-nitro-2-aminophenol, which comprises the following steps: by using 2-chloro-4-nitroaniline as a raw material, providing an amino protecting group by using di-tert-butyl dicarbonate ester to obtain a compound 3; carrying out hydrolysis reaction in an alkaline environment to hydrolyze chlorine groups on benzene rings into hydroxyl groups to obtain a compound 4; and removing an amino protecting group under an acidic condition to obtain the 5-nitro-2-aminophenol. According to the method, 2-chloro-4-nitroaniline is used as a starting raw material, compared with expensive ortho-aminophenol, the cost of the raw material can be remarkably reduced, use of expensive catalysts in the hydrolysis process is avoided through amino protection, generation of the byproduct 2-amino-4-nitrophenol is effectively reduced, and the yield of the 2-chloro-4-nitrophenol is increased. And the synthesized 5-nitro-2-aminophenol has relatively high purity (99.5%) and relatively high yield (-86%). The method has the advantages of conventional production steps and conventional process equipment, and has a good application prospect.

The application discloses a method for continuously fermenting urine to produce safe fertilizer, which comprises the following steps: in the first fermentation, adding environment-friendly enzyme into a container, then collecting fresh urine and adding molasses, and carrying out fermentation in a sealed manner; after the fermentation is completed, reserving part of the fermentation liquor as a substrate; and in the subsequent batches, directly adding fresh urine and molasses into the container with the substrate to carry out fermentation, so as to realize continuous circulation. The method can inhibit the hydrolysis process of urea in the urine in the early stage by timely adding environment-friendly enzyme (or the fermentation liquor of the last time) and molasses into the fresh urine to carry out fermentation, thereby greatly reducing the ammonia nitrogen volatilization amount, and the pathogenic bacteria in the urine can be inhibited to a very low level in a short period of time. Except that the environment-friendly enzyme needs to be added in the first fermentation, the environment-friendly enzyme does not need to be added in the subsequent batches of fermentation, and only a small amount of molasses needs to be added. A large amount of beneficial bacteria such as lactic acid bacteria and yeast and metabolic products such as lactic acid and acetic acid are generated in the fermentation process, so that the urine is converted into microbial bacterial fertilizer.

The invention provides a compound enzyme preparation and application thereof, and belongs to the technical field of compound enzymes. The complex enzyme preparation is composed of the soluble polysaccharide monooxygenase, the hemicellulase and the trivalent rare earth metal ions, has high stability and high activity, and can reduce the use amount of the enzyme in the enzymatic hydrolysis process of the lignocellulose material, so that the yield of the lignocellulose material is increased. The enzymolysis efficiency of the lignocellulose material is improved; and the production cost of preparing a sugar product from the lignocellulose material is reduced.

The application discloses a preparation method of high-purity titanium dioxide, which comprises the following steps: S1, titanium tetrachloride is slowly mixed with an aqueous hydrochloric acid solution to obtain a primary hydrolysis material containing titanium oxychloride and hydrochloric acid; S2, the primary hydrolysis material is mixed with water and subjected to secondary hydrolysis at 90-110 DEG C, and then solid-liquid separation is conducted after hydrolysis to obtain metatitanic acid precursor; and S3, the metatitanic acid precursor is calcined to obtain high-purity titanium dioxide. In the application, titanium tetrachloride is directly mixed with an aqueous hydrochloric acid solution under the conditions of a limited concentration and a limited amount at room temperature to generate a mixed solution of titanium oxychloride and hydrochloric acid, and then the mixed solution of titanium oxychloride and hydrochloric acid is subjected to secondary hydrolysis under the condition of a limited high temperature. Compared with direct hydrolysis of an aqueous titanium tetrachloride solution, the hydrolysis process does not need to be conducted under a low-temperature condition, there are less intermediate products, the reaction is easy to control, titanium oxychloride is fully hydrolyzed, and the hydrolysis rate is more than 99.0%.

The utility model belongs to the technical field of chemical engineering and silica sol production, and particularly relates to a novel reaction kettle for silica sol production, which comprises a kettle body and a kettle cover positioned at the top of the kettle body and clamped into the kettle body to be matched with the kettle body, a stirring component is mounted in the kettle cover, and a torque sensor is mounted on the outer wall of a motor shaft on a driving motor of the stirring component. The outer wall of the kettle cover is provided with a quantitative water adding assembly, the quantitative water adding assembly is composed of a hydraulic push rod, a quantitative container and an atomizing head, a piston of the hydraulic push rod slides in the quantitative container, the other end of the quantitative container is communicated with the atomizing head, and the outer wall of the quantitative container close to the atomizing head is communicated with a water inlet pipe. Dehydration in the hydrolysis process of silica sol preparation is avoided, external air entering the kettle body is reduced, water can be continuously and quantitatively added, and the hydrolysis effect is prevented from being affected by direct contact of a large amount of water and materials.

The present application relates to the technical field of hydrolysis of hydroxy fatty acid ester, and discloses a hydrolysis filler, a preparation method and application thereof. The hydrolysis filler comprises a silane layer and an active layer which are successively coated on the outer surface of the filler; the active layer comprises amido, pyrrolyl, and sulfhydryl and / or thioether, phosphoric acid group and sulfonic acid group. When the hydrolysis filler is used for hydrolysis of hydroxy fatty acid ester to prepare hydroxy glycolate aqueous solution, the water-ester ratio in the hydrolysis process and the oligomer content in the target product can be effectively reduced.

The utility model discloses a wastewater zero discharge system in a furfural production process. The wastewater zero discharge system comprises a hydrolysis kettle, a stock solution condenser, a stock solution distillation tower, a wastewater tank, a wastewater evaporator and a concentrated solution tank, the device has the advantages that secondary steam generated by the wastewater evaporator is used as a heat source in the hydrolysis process and then converted into aldehyde gas; the aldehyde gas condensate is distilled by the stock solution distillation tower to generate wastewater again, and the wastewater is discharged from the bottom of the tower to form a closed cycle; evaporation concentration residual liquid generated by the wastewater evaporator is used for preparing dilute acid in the hydrolysis process, so that wastewater is not discharged, meanwhile, 1-2% of acetic acid and a small amount of furfural in the wastewater can be effectively recycled, the use amount of sulfuric acid is reduced, and the yield of furfural is increased; moreover, the consumption of the sulfuric acid is reduced, so that the sulfur content in the boiler flue gas can be reduced, the pollution to the atmosphere is reduced, and clean production of furfural is realized.

The invention discloses a method for enhancing production of fatty acid by anaerobic fermentation of sludge based on sulfate synergistic electron transfer. The method comprises the following steps: placing residual sludge and inoculated sludge in an anaerobic fermentation device, uniformly stirring and mixing, and then adjusting the initial pH value; then adding a sulfate solution, and continuously stirring and uniformly mixing at 20-25 DEG C; removing oxygen in the anaerobic fermentation device with nitrogen, and sealing the anaerobic fermentation device; and carrying out anaerobic fermentation in a constant-temperature shaking table. By introducing sulfate, sludge flocs and cell structures can be effectively destroyed, the hydrolysis process is remarkably enhanced, and organic matter release is promoted. Meanwhile, sulfate serves as an electron acceptor to mediate electron transfer, efficient conversion of organic matter to the short-chain fatty acid is promoted, and therefore the yield of the short-chain fatty acid is remarkably increased. The method is easy and convenient to operate and remarkable in strengthening effect and has a good application prospect.

The invention discloses a method for epitaxial synthesis of a two-dimensional metal sulfide XS2 thin film, which is based on the fact that Ba < 2 + > and XO4 < 2-> can form precipitate BaXO4, X is Mo or W, BaXO4 covers a substrate, BaXO4 is vulcanized to form a sulfide mixed phase BaS / XS2, BaS is hydrolyzed in water to be removed, the XS2 except the surface of the substrate falls off due to H2S gas generated in the BaS hydrolysis process, and finally the thin layer XS2 thin film is obtained on the surface of the substrate. The method has the advantages of low equipment requirements, easily controlled reaction conditions, few influence factors, simple process, low raw material cost, good repeatability and the like.

The application discloses a preparation method of rutile phase nano titanium dioxide with controllable particle size, which comprises the following steps: constructing a water bath reaction environment by using a mixed solution of anhydrous ethanol and super-dry acetonitrile, adding benzoic acid, making the benzoic acid react with tetrabutyl titanate in the reaction environment and controlling the hydrolysis process of the tetrabutyl titanate, adding a mixed solution containing deionized water into the reaction to add appropriate hydrolysis sites into the formed tetrabutyl titanate-benzoic acid complex, then treating the precipitate and grinding the precipitate into a semi-finished powder, and finally carrying out microwave hydrothermal reaction on the semi-finished powder and anhydrous oxalic acid to obtain the rutile phase nano titanium dioxide with controllable particle size. The preparation method of the rutile phase nano titanium dioxide with controllable particle size effectively avoids high temperature and long time reaction required by traditional high-temperature calcination, is simple in overall scheme steps, convenient to operate, relatively low in material cost, safe and controllable in process, and clean and environmentally-friendly.

The invention belongs to the technical field of biological process monitoring and optimization, and discloses a fermentation-hydrolysis process parameter automatic control system and method, and the method comprises the steps: collecting online process parameter time sequence data for pre-selected key process parameters; taking the online process parameter time sequence data as real-time input, and utilizing a pre-trained soft measurement model to obtain a key metabolite estimation concentration value sequence; calculating to obtain a key metabolite estimation generation rate value sequence based on the key metabolite estimation concentration value sequence; forming a real-time two-dimensional state vector based on the current estimated concentration value of the key metabolite and the current estimated generation rate value of the key metabolite; comparing and evaluating the real-time two-dimensional state vector with a predefined decision logic; when the decision logic judges that a preset triggering condition is met, a decision signal for starting hydrolysis is obtained; and the optimal opportunity for starting hydrolysis is accurately captured.

The utility model discloses a corncob hydrolysis device, which belongs to the technical field of furfural production equipment and comprises a hydrolysis kettle and a heating component, the top of the hydrolysis kettle is fixedly connected with a feed pipe, a stirring mechanism is arranged in the hydrolysis kettle and comprises a hollow shaft, and the hollow shaft is rotatably connected to the middle position of the top of the hydrolysis kettle. A plurality of stirring blades are fixedly connected to the side surface of the hollow shaft. The device has the beneficial effects that the air supply mechanism and the pressurization mechanism are arranged, high-temperature steam is supplied into the hollow shaft through the steam inlet pipe and the air supply shell and is sprayed out through the air outlet holes in the air outlet barrel, the heating uniformity in the hydrolysis process is enhanced, the hydrolysis efficiency is improved, the air pressure in the hollow shaft is changed through the lifting shaft which reciprocates up and down, and the hydrolysis effect is improved. The pressure of spraying high-temperature steam is changed at any time, various reactants in the hydrolysis kettle form turbulent flow, the reaction speed is increased, and the production efficiency is improved.

The application relates to a method for preparing high-purity alpha-Al2O3 by hydrolysis and one-time calcination of an aluminum alloy, and belongs to the technical field of alumina preparation. Aluminum, gallium, indium and tin are used as raw materials, a melt is obtained after melting, flaky aluminum alloy is prepared, and the flaky aluminum alloy is crushed into powder and reacts with pure water, solid and hydrogen are collected respectively, and high-temperature calcination is carried out under a hydrogen atmosphere, thereby obtaining high-purity alpha-Al2O3. The activity of the aluminum is activated by preparing an aluminum-gallium-indium-tin alloy, and the broken aluminum alloy powder is used for hydrolysis reaction, so that the reaction rate is larger, the impact of hydrogen on the product is larger during the hydrolysis process, the particle size of the product is smaller, the removal of impurities in the calcination process is more favorable, the purity of the alumina obtained after the calcination is larger, and the particle size is smaller.

The present invention provides a method for the comprehensive recycling and utilization of secondary aluminum ash and the co-production of high-purity hydrogen. In the method, the secondary aluminum ash is first pretreated with an ammonium chloride solution to hydrolyze aluminum nitride, aluminum carbide, and other substances in the aluminum ash, dissolving and recovering salts to increase process safety. The waste liquid is then recycled and reused multiple times through evaporation and crystallization to reduce carbon and recover salts, thereby increasing the utilization efficiency of the sodium element during the alkaline treatment process. The gas recovery and utilization during the aluminum ash hydrolysis process is then optimized, using the low-concentration ammonia water obtained through absorption to absorb carbon dioxide, and ammonium chloride is recycled and accumulated, avoiding the use of strong acid absorption and reducing equipment costs. Pressure swing adsorption is used to purify the gaseous components to the purity required for fuel cells. The method provided by the present invention reduces the high-temperature and corrosion resistance requirements of the equipment during the alkaline wet treatment of secondary aluminum ash, fully recovers the sodium element input during the alkaline treatment process and the soluble salts in the secondary aluminum ash, and achieves harmless treatment of the aluminum ash, with outstanding economic and environmental benefits.

The invention relates to the technical field of coatings, and discloses a degradable environment-friendly bio-based coating and a preparation method thereof.The preparation method comprises the steps that polycaprolactone diol, diisocyanate, a chain extender, hydroxyl-terminated hyperbranched polyester, dibutyltin dilaurate and the like are subjected to a reaction, then a neutralizer, water, a coalescing agent and other raw materials are added, and the degradable environment-friendly bio-based coating is prepared. The degradable environment-friendly bio-based coating is obtained. The hydroxyl-terminated hyperbranched polyester contains a rigid and thermal-stable benzene ring structure, so that the mechanical strength and heat resistance of a paint film of the paint are improved, and the paint film shows higher impact resistance, tensile strength and thermal decomposition temperature. Hyperbranched polyester contains a large number of degradable ester groups and amido bond hydrophilic groups, and is introduced into a polyurethane molecular chain, so that the biodegradation and hydrolysis processes of the polyurethane coating can be accelerated, and the biodegradation mass loss rate is increased.

The utility model discloses a kind of hydrolysis devices for producing triclosan, including hydrolysis reactor, hydrolysis reactor;Hydrolysis reactor is equipped with stirring mechanism, and stirring mechanism includes stirring shaft, spiral stirring vane, stirring motor interface, spiral stirring vane is also equipped with multiple non-parallel setting auxiliary stirring vane, spiral stirring vane and auxiliary stirring vane are equipped with turbulence hole;The bottom of stirring shaft is equipped with buffer cavity, and buffer cavity is communicated with the hollow stirring rod of being arranged in the lower portion of stirring shaft, and the main gas outlet hole is equipped on the hollow stirring rod;The bottom of stirring shaft is communicated gas pipeline by swivel joint;The inner wall of hydrolysis reactor is equipped with annular array ultrasonic transducer.This device guarantees that hydrolysis reaction is carried out fully, avoids the occurrence of side reaction, improves the production efficiency of product, and tail gas produced in hydrolysis process is fully treated, avoids its pollution to environment.

The present invention belongs to the field of biomass conversion and specifically relates to a method for preparing oligosaccharides from biomass. The method comprises pre-treating the biomass to obtain a sugar solution; enzymatically hydrolyzing the sugar solution to obtain an enzymatic hydrolyzate; decolorizing the enzymatic hydrolyzate; preparing copper-doped porous silica; grafting hydroxymethyl groups onto the surface of the porous silica to obtain modified silica; and purifying the decolorized enzymatic hydrolyzate using the modified silica to remove acid and xylose. The method can separate small molecular byproducts and impurities such as acid and xylose produced during the hydrolysis process, thereby reducing the cost of preparing and purifying xylooligosaccharides.

The application provides a seed crystal for carbon dioxide fixation, and a preparation method and application thereof, and belongs to the technical field of environmental protection and water treatment. The seed crystal comprises a carrier material and basic active sites loaded on the carrier material; and the material of the basic active sites comprises one or more of alkali metal oxides and alkaline earth metal oxides. The seed crystal provided by the application can be applied to a seed crystal granulation process, the basic active sites on the surface of the seed crystal can consume a large amount of hydrogen ions, accelerate the dissolution and hydrolysis process of gaseous carbon dioxide, convert the gaseous carbon dioxide into carbonate ions in a high-efficient manner, and then induce metal ions to crystallize on the surface of the seed crystal in the form of carbonate precipitation, so that carbonate granules are formed, and the mineralization and fixation of carbon dioxide and the high-efficient removal and granulation recovery of metal ions in wastewater are simultaneously achieved.

The utility model provides a condensing device and an acid hydrolysis instrument, and relates to the technical field of acid hydrolysis. The condensing device provided by the utility model comprises a condensing cover assembly and a condensing pipe, the condensation cover assembly is used for covering the hydrolysis container, and the condensation cover assembly is provided with a first cooling liquid flow path; the condensation pipe is connected with the condensation cover assembly; the condensation pipe is provided with a condensation gas path and a second cooling liquid flow path, the condensation gas path exchanges heat with the second cooling liquid flow path, and the condensation gas path is in fluid communication with the hydrolysis container. In the hydrolysis process, one part of steam can be shielded and condensed by the condensation cover assembly so as to flow into the hydrolysis container, and the other part of steam can be condensed into a liquid state in the condensation gas path and flows back into the hydrolysis container, so that the technical problem that the concentration of hydrolysate is changed due to evaporation is relieved, the concentration of the hydrolysate can be kept stable, and the hydrolysis efficiency is improved. And the influence of acid gas on the atmospheric environment is avoided.

The invention belongs to the technical field of molecular sieve preparation, and provides a boron-doped MFI type hierarchical pore molecular sieve and a preparation method thereof. The preparation method comprises the following steps: mixing an organic template agent solution, a silicon source and a boron source to obtain reaction precursor gel; and sequentially carrying out hydrothermal crystallization and roasting on the reaction precursor gel to obtain the boron-doped MFI type hierarchical pore molecular sieve, the boron source is hydroboron. According to the method, borate released by slow hydrolysis of hydroboron is used as a boron source, hydrogen released in the hydrolysis process is used as a soft template, modulation of the pore channel structure of the molecular sieve is realized, and the molecular sieve with a micro-mesoporous structure is constructed, so that the mass transfer efficiency of the MFI type molecular sieve is improved, and limitation of steric hindrance and diffusion resistance is reduced.

The present invention discloses a method for recovering glycolic acid from polyglycolic acid and its application. The method comprises the following steps: step A, mixing polyglycolic acid, an organic solvent and water; step B, subjecting the product of step A to liquid-liquid separation to obtain an aqueous phase and an organic solvent phase. The method for recovering glycolic acid from polyglycolic acid provided by the present invention adopts a method of simultaneously hydrolyzing and extracting polyglycolic acid, water and an organic solvent, and adding an organic solvent during the hydrolysis process so that the glycolic acid obtained by hydrolysis enters the aqueous phase, and the colored impurities and unhydrolyzed oligomers generated during the hydrolysis process are dissolved in the organic solvent oil phase, thereby enabling the glycolic acid to be quickly separated, promoting the progress of the hydrolysis process, making the hydrolysis process more thorough, and the obtained glycolic acid has a low impurity content and a high purity, and the obtained glycolic acid can directly meet the recycling needs.

The invention relates to a preparation method of a subcritical water-based waste cattle hair hydrolysis modified protein filler, which comprises the following steps: pretreatment: cleaning and soaking waste cattle hair to obtain a pretreatment solution; hydrolysis: adding the pretreatment liquid into a subcritical water treatment device, adding clear water, and heating to 180-200 DEG C for reaction; filtering: filtering the hydrolysate to obtain filtrate; modifying: adjusting the pH value of the filtrate to 8-10, adding sodium polyacrylate, and reacting to obtain a modified protein solution; and purifying, and drying the modified protein liquid to obtain the protein modified filler. According to the preparation of the filler, only water and waste cattle hair need to be added in the hydrolysis process, substances participating in the reaction are few, the hydrolysis cost is low, and secondary pollution cannot be caused.

The invention belongs to the technical field of wastewater treatment, and discloses a supported zirconium hydroxide adsorption material convenient to separate as well as a preparation method and application thereof. According to the invention, the absorbent cotton which is cheap and easy to obtain is used as a carrier, a zirconium hydroxide adsorbent is prepared by using a zirconium oxychloride hydrolysis method, and the adsorbent can coat the surface of the absorbent cotton fiber in the hydrolysis process, so that the supported zirconium hydroxide adsorption material convenient to separate can be obtained. The supported zirconium hydroxide adsorption material can effectively remove various anions in a solution, is easy to separate and recover in the adsorption process, is low in loss rate and lower in production cost, can be repeatedly utilized, and is beneficial to large-scale production and popularization.