60 results about "M-aminophenol" patented technology

This invention discloses a weather-resistant, high-hardness composite anti-corrosion coating and its preparation method, belonging to the field of anti-corrosion coating technology. The preparation method includes: firstly, synthesizing an epoxy resin containing dynamic disulfide bonds by reacting dithiodibenzoic acid and epichlorohydrin in an alkaline aqueous phase; secondly, constructing a low surface energy siloxane network using hydroxyl-terminated polydimethylsiloxane and methyltriethoxysilane; subsequently, introducing chlorzoxazone and N-acetyl-p-aminophenol as composite organic corrosion inhibitors, blending them with the resin to obtain a composite base material; finally, adding graphene, carbon nanotubes, and inorganic anti-corrosion fillers, and cross-linking and curing to form a film using a polyamine curing agent. This invention suppresses microcracks through the dynamic stress relief of disulfide bonds, combined with the weather-resistant barrier of the siloxane network, the active interface passivation of the heteroatom corrosion inhibitor, and the three-dimensional synergistic mechanical bonding of carbon-based nanomaterials, achieving a perfect unity of ultra-strong corrosion resistance, excellent weather resistance, and high mechanical hardness in the coating.

The invention provides a catalyst component for olefin polymerization, a preparation method and application of the catalyst component, a catalyst containing the catalyst component and used for olefin polymerization and application of the catalyst. The catalyst component comprises a reaction product of a sulfur-containing magnesium compound as shown in a formula (I), a titanium compound and an internal electron donor compound, in the formula (I), R1 is selected from C1-C8 alkyl groups or C3-C8 cycloalkyl groups; r2 and R3 are the same or different and are independently selected from hydrogen or C1-C5 alkyl groups, and hydrogen on the alkyl groups can be optionally substituted by halogen atoms; x is halogen, preferably chlorine or bromine; m ranges from 0.1 to 1.9, n ranges from 0.1 to 1.9, and m + n = 2, 0lt; q < = 0.5; the internal electron donor compound comprises a 1, 3-diether compound and an aminophenol compound. When the catalyst component for olefin polymerization provided by the invention is used for olefin polymerization, the hydrogen regulation sensitivity is relatively low, the stable control of the melt index of the product is facilitated, and the melting point of the prepared polymer product is lower.

The invention relates to the technical field of electrochemical materials, and particularly discloses Mo2C loaded N and P co-doped carbon nanospheres as well as a preparation method and application thereof. The preparation method comprises the following steps: by taking 3-aminophenol-formaldehyde phenolic resin nanospheres as a carbon precursor, forming a uniform Mo-EDTA (Ethylene Diamine Tetraacetic Acid) complex by utilizing a polydentate coordination effect of EDTA on Mo ions; when one-step carbonization is carried out in an inert atmosphere, EDTA serves as a molecular cage to inhibit Mo2C nano-particle agglomeration and realize monodisperse anchoring, and N and P sources are released in situ to complete double-heteroatom uniform doping. The catalyst shows excellent catalytic performance in a water electrolysis hydrogen production performance test: in a 1M KOH electrolyte, when the current density is 10mA / cm < 2 >, the overpotential is less than or equal to 80mV, and the Tafel slope is 95-105mV / dec. The long-term stability is good, hydrogen evolution is continuously conducted for 23 h under the current density of 50 mA / cm < 2 >, and the current retention rate is larger than or equal to 90%.

The application discloses an acid-resistant non-noble metal catalyst and a preparation method and application thereof, and particularly relates to the field of acid-resistant metal catalysts, and the preparation method of the acid-resistant non-noble metal catalyst comprises the following steps: step 1, preparation of a carrier; step 2, modification of the carrier; step 3, preparation of an impregnation solution; step 4, preparation of an unactivated catalyst; step 5, activation of the catalyst; and step 6, functionalization of the catalyst. The acid-resistant non-noble metal catalyst prepared by the application can be applied to the synthesis of p-aminophenol from nitrobenzene. The catalyst has good acid resistance and stability, and when applied to the process of preparing p-aminophenol by rearrangement of nitrobenzene hydrogenation, the catalyst has high activity and high selectivity of p-aminophenol under relatively mild reaction conditions, the production conditions are improved, the production cost is reduced, and the product quality is improved.

The invention belongs to the technical field of electrolytic synthesis, and particularly relates to a method for synthesizing p-aminophenol and persulfate. According to the application, a cathode electrocatalytic reduction synthesis process of p-aminophenol and an anode electrocatalytic oxidation synthesis process of persulfate are innovatively coupled, and the cathode current efficiency in the preparation process of p-aminophenol is effectively improved by regulating and controlling anode electrocatalytic temperature parameters. Performance test results show that the cathode current efficiency can reach 81.3%-89.82%, and compared with the cathode current efficiency of 80% or below in a conventional p-aminophenol preparation process, the technical breakthrough exceeding the expectation is achieved, and the unexpected technical effect is shown.

The invention relates to the technical field of laboratory waste treatment, in particular to a method for preparing alumina-based magnesium aluminate spinel by recycling laboratory waste. The waste recycling device is used for solving the problems of environmental pollution and resource waste caused by waste materials generated in existing laboratories. The method comprises the following steps of: settling and drying the waste material, grinding the waste material, high bauxite, biphenyl aminophenol aldehyde epoxy resin and niobium pentoxide, and calcining to form alumina-based magnesium aluminate spinel; the preparation method comprises the following steps: carrying out nucleophilic substitution reaction on 4, 4 '-biphenyl dimethyl dimethyl ether and 4-aminophenol to prepare an intermediate product 1, and carrying out nucleophilic ring opening and polymerization reaction on the intermediate product 1 and epoxy chloropropane to generate the biphenyl aminophenol aldehyde epoxy resin. According to the method, environmental pollution caused by direct discharge of waste materials is avoided, the production cost is reduced, cyclic utilization of resources is realized, ecological damage caused by raw material exploitation can be reduced, and the method has a remarkable environmental protection effect.

The invention discloses 2-((4-aminopyridine-2-yl) amino)-4-methylphenol as well as a synthesis method and application thereof, 2-bromo-4-methylphenol and 4-nitropyridine-2-amine are taken as raw materials, and an intermediate 4-methyl-2-((4-nitropyridine-2-yl) amino) phenol is obtained through condensation reaction; and reducing the intermediate under the action of ammonium formate and a catalyst to obtain the 2-((4-aminopyridine-2-yl) amino)-4-methylphenol. The method is simple and convenient to operate, mild in operation condition and high in reaction rate, the obtained product is high in purity and yield, the dispersity and antistatic performance of the insoluble sulfur can be improved, and the method is suitable for industrial mass production.

The invention discloses a production method of a high-temperature-resistant lithium battery base membrane. The lithium battery base membrane is prepared from PA6, PA10T / 66, magnesium hydroxide, glass fibers, zinc borate, an antioxidant, silane coupling agent modified silicon dioxide and a DOPO-triglycidyl p-aminophenol reaction product. The high-temperature-resistant lithium battery base membrane designed by the invention not only has excellent high-temperature resistance, but also has good mechanical properties.

The invention provides an olefin polymerization catalyst carrier as well as a preparation method and application thereof. The olefin polymerization catalyst carrier comprises a composition shown in a formula (I), and in the formula (I), R1 is selected from C1-C14 alkyl groups or C3-C14 cycloalkyl groups; r2 and R3 are the same or different, and are respectively and independently selected from H, C1-C5 alkyl or C1-C5 halogenated alkyl; x is selected from halogen; m is 0.1-1.9, n is 0.1-1.9, and m + n = 2; c1 is selected from aminophenol compounds, 0 lt; q < = 0.5. The carrier is good in morphology, particles are not adhered, the carrier is in a good spherical shape, the particle size of the particles is small, and the particle size distribution is narrow. The catalyst prepared by adopting the carrier to carry out titanium loading has better catalytic activity and ethylene copolymerization capability when being used for olefin polymerization, is sensitive to hydrogen response, and can be used for preparing polymer products with higher bulk density.

The invention relates to the technical field of fluorescent dye preparation, in particular to an organic fluorescent dye and a preparation method thereof.The preparation method comprises the following steps that m-diethylaminophenol and Meldrum's acid are catalyzed in an ethanol-water solvent through a supported catalyst and stirred to react in an oil bath, and an intermediate is obtained through acidification crystallization after cooling; and heating the intermediate, anhydrous potassium carbonate and ethyl iodoacetate in N, N-dimethylformamide under the protection of nitrogen to carry out alkylation reaction, and carrying out recrystallization, saponification hydrolysis and purification on the reaction liquid to obtain the organic fluorescent dye coumarin 343. The supported catalyst prepared by the invention shows good catalytic performance, stability and recoverability in the preparation reaction of the organic fluorescent dye.

Polymers formed by the condensation of bis(hydroxycarbyl)-aminophenol compounds with aldehydes are disclosed. The condensation polymers include one or more repeating units having bis(hydroxycarbyl)amino functionality. The polymers are useful as antifouling agents, polymerization inhibitors, rheology modifiers, dehaze agents, polymerization retarders, surfactants, or combinations thereof in one or more industrial process streams.

The invention discloses 4, 4 '-(propane-2, 2-diyl) bis (2-((4-aminopyridine-2-yl) amino) phenol) as well as a synthesis method and application of the 4, 4'-(propane-2, 2-diyl) bis (2-((4-aminopyridine-2-yl) amino) phenol). The preparation method comprises the following steps: by taking 4, 4 '-(propane-2, 2-diyl) bis (2-bromophenol) as a raw material, carrying out step-by-step substitution reaction to obtain an intermediate 4, 4'-(propane-2, 2-diyl) bis (2-((4-nitropyridine-2-yl) amino) phenol), and reducing the intermediate under the action of a catalyst and hydrazine hydrate to obtain the 4, 4 '-(propane-2, 2-diyl) bis (2-((4-aminopyridine-2-yl) amino) phenol). The method is high in production efficiency, short in production period, environment-friendly, simple and convenient to operate, high in product purity and high in yield, the solvent is convenient to recycle, the dispersity and the antistatic property of the insoluble sulfur can be improved, and the method is suitable for industrial mass production.

The application relates to application of a solid acid catalytic catalyst in preparation of p-aminophenol through nitrobenzene hydrogenation. The application comprises the following steps: adding a solid acid catalyst, cetyltrimethylammonium bromide, deionized water and nitrobenzene into a high-pressure reactor, and reacting under magnetic stirring for 0-24 hours at 25-150 DEG C to obtain the product p-aminophenol. The activated carbon for preparing the solid acid catalyst is coconut shell activated carbon, the series of activated carbon has the advantages of large specific surface area, rich micropores and strong adsorption capacity, and the coconut shell activated carbon solid acid with different acidities is prepared to catalyze the nitrobenzene hydrogenation reaction. The application avoids using traditional liquid acid sulfuric acid to provide the acidic active sites required by the reaction, greatly alleviates the problems of equipment corrosion, environmental unfriendliness, catalyst and product separation difficulty and the like. The catalyst used has good performance, the conversion rate of nitrobenzene is up to 100%, and the yield of p-aminophenol is up to 81.17%.

The invention relates to the technical field of photocatalysts, in particular to a nonmetal plasmon heterojunction material, a preparation method and application thereof and a method for preparing p-aminophenol through reduction of p-nitrophenol. The nonmetal plasmon heterojunction material provided by the invention comprises a C3N4 nanosheet and a WO3-x nanoplate (x is 0.1 to 0.3) positioned on the surface of the C3N4 nanosheet. The WO3-x local surface plasmon characteristic can effectively expand the spectral response range of the non-metal plasmon heterojunction material in a visible region to a near-infrared region, and the light absorption efficiency of the non-metal plasmon heterojunction material is remarkably enhanced. The nonmetal plasmon heterojunction material provided by the invention can realize efficient reduction of p-nitrophenol based on the synergistic effect of an interface heterojunction, a built-in electric field and oxygen vacancies, is high in selectivity, has excellent photocatalytic activity for reduction of p-nitrophenol, and is excellent in photocatalytic activity stability.

The application belongs to the technical field of sensors and relates to an array sensor based on cerium-based metal organic framework nanoscale enzyme and detection application of perfluoroalkyl compounds. The array sensor is a Ce-MOF triple enzyme activity array sensor and has multiple independent sensing channels. The sensing channels contain Ce-MOF nanoscale enzyme and chromogenic substrate. The chromogenic substrate includes first, second and third chromogenic substrates. The first chromogenic substrate includes 3,3',5,5'-tetramethylbenzidine. The second chromogenic substrate includes 2,4-diamino phenol and 4-aminoantipyrine. The third chromogenic substrate includes xanthine, xanthine oxidase and nitrogen blue tetrazolium. The MOF nanoscale enzyme array sensor constructed by the application has high sensitivity and selectivity in the identification and differentiation of PFASs compounds. The array sensor can not only accurately distinguish single PFASs compounds but also quantitatively detect the compounds, and has good response to PFASs with different concentrations.

The invention discloses water-soluble red light carbon dots (RCDs), a preparation method thereof and application of the water-soluble red light carbon dots in ammonia gas detection. The RCDs are prepared by taking 2, 4-diaminophenol hydrochloride as a single precursor, synthesizing through a one-step hydrothermal method and then dialyzing and purifying. The method is simple and low in cost. The particle size of the obtained RCDs is about 1.6 nm, the water solubility is good, and the emission wavelength is 610 nm. RCDs are loaded on filter paper to prepare the paper-based sensor, and after the sensor is in contact with ammonia gas, the fluorescence color (or R / G intensity ratio) of the sensor can generate specific change. According to the invention, the sensor is utilized to realize visual and quantitative detection of ammonia gas in a range of 1-100 [mu] M, and the anti-interference capability is strong. The whole detection process does not need complex instruments, and the method is suitable for on-site rapid detection of environmental monitoring, food freshness evaluation and the like.

The present disclosure provides for latent curing accelerators as well as compositions containing such a latent curing accelerator with a substance to be cured (e. g., an epoxy resin). The latent curing accelerators comprise an aminophenol and an encapsulant system having a polyphenol resin and optionally an acrylic resin. Methods of making and use are further provided.

This invention belongs to the field of sodium-ion battery technology, specifically relating to a nitrogen-doped hard carbon material, its preparation method and application, a sodium-ion battery anode, and a sodium-ion battery. This invention uses aminophenol as a dopant, which introduces nitrogen (N) into the hard carbon material, increasing the interlayer spacing and facilitating sodium ion intercalation. Simultaneously, the introduction of N can regulate the defect structure of the hard carbon material, enriching sodium storage sites. Based on these reasons, the specific capacity and cycle performance of the final hard carbon material are improved.

The invention provides a preparation method of a non-foaming agent dependent type foaming material, which adopts a Schiff base product (HB-AP) as a precursor, and realizes the integration of foaming and material preparation through a high-temperature self-crosslinking reaction. The preparation method comprises the following steps: taking 4-hydroxybenzaldehyde and 4-aminophenol as raw materials, and reacting to obtain HB-AP; then, under the precise temperature control condition of 240-300 DEG C, the inherent high-temperature self-crosslinking characteristic of HB-AP is utilized, and the foaming material with a porous structure can be directly obtained without adding any chemical foaming agent. The method breaks through the dependence of a traditional foaming technology on a foaming agent, in-situ control of the foaming process is achieved through molecular design, the preparation process is simplified, and the environmental problem caused by foaming agent residues is avoided. The obtained material has a uniform pore structure and high thermal stability, and has remarkable application advantages in the fields of thermal insulation and the like.

The application discloses a kind of wastewater treatment processes for p-aminophenol production, belong to p-aminophenol wastewater treatment technical field.First by graphene, anion exchange resin and hyperbranched polyether amine as raw material, prepared adsorption material, to wastewater is first step processing, reduce the content of TOC and metal ion, then through Fenton process second step processing, make hydrogen peroxide and ferrous ion reaction produce strong oxidizing hydroxyl radical, to attack difficult degradation organic matter chemical bond, and reduce COD in wastewater, reduce the harm to environment, finally into ceramic membrane filtration, ceramic membrane has good performance in wastewater treatment, by cross-flow filtration mode, can long-term stable in wastewater separation pollutant, complete p-aminophenol production wastewater treatment process.

The invention discloses sound-absorbing anti-electromagnetic wave glass and a preparation method thereof, and relates to the technical field of glass. The preparation method comprises the following steps: firstly, enabling 4-amino-2-ethoxy-5-nitrobenzoic acid, sodium nitrite, 2-tert-butyl-4-aminophenol and 2-amino-5-chlorobenzaldehyde to react to prepare an anti-ultraviolet agent, absorbing ultraviolet light energy by utilizing opening and closing of a chelate ring structure, and converting the ultraviolet light energy into heat energy to be released, so that the glass has an anti-ultraviolet effect; then preparing an anti-electromagnetic wave layer from the aminated indium tin oxide fibers, an anti-ultraviolet agent, pyromellitic dianhydride and 5-aminothiophene-2-formaldehyde, and enabling the glass to have an anti-electromagnetic wave effect through a multi-level electromagnetic loss structure and intensifying multiple reflection of electromagnetic waves; and compounding the anti-electromagnetic wave layer, the polyvinyl butyral film and the two layers of toughened glass to prepare the sound-absorbing anti-electromagnetic wave glass. The glass prepared by the invention has anti-electromagnetic wave and anti-ultraviolet effects.

The invention provides an olefin polymerization catalyst as well as a preparation method and application thereof. The catalyst comprises titanium halide, magnesium halide and a diether electron donor compound; the magnesium halide is a reaction product of titanium halide and an olefin polymerization catalyst carrier comprising a composition shown as a formula (I), and in the formula (I), R1 is selected from C1-C14 alkyl or C3-C14 cycloalkyl; r2 and R3 are the same or different, and are respectively and independently selected from H, C1-C5 alkyl or C1-C5 halogenated alkyl; x is selected from halogen; m is 0.1-1.9, n is 0.1-1.9, and m + n = 2; c1 is selected from aminophenol compounds, 0 lt; q < = 0.5. When the olefin polymerization catalyst provided by the invention is used for olefin polymerization, the particle fluidity of the catalyst is obviously improved, the catalyst has good catalytic activity and good hydrogen regulation sensitivity, and a prepared polymer product has relatively high bulk density, wider molecular weight distribution and shorter falling time.

The invention discloses a glycine-derived nitrogen-doped carbon-coated platinum catalyst as well as a preparation method and application thereof. The preparation method of the catalyst comprises the following steps: (1) adding a supported platinum catalyst into a uniform glycine aqueous solution, and uniformly dispersing the supported platinum catalyst; (2) transferring the mixture into a reaction kettle for hydrothermal reaction; (3) cooling the mixture to room temperature, collecting a product through suction filtration, fully washing with ethanol, and then carrying out vacuum drying; and (4) grinding the dried product into uniform powder, and roasting for 2-10 hours at a high temperature of 300-800 DEG C in an inert protective atmosphere to prepare the glycine-derived nitrogen-doped carbon-coated platinum catalyst. The invention provides the application of the glycine-derived nitrogen-doped carbon-coated platinum catalyst in preparation of p-aminophenol through nitrobenzene hydrogenation rearrangement, and the glycine-derived nitrogen-doped carbon-coated platinum catalyst shows high catalytic activity, high selectivity and high stability.

This invention relates to the field of fiber optic ribbons and discloses a high-fiber-density woundable fiber optic ribbon and its preparation method. The high-fiber-density woundable fiber optic ribbon includes multiple optical fibers arranged in parallel and a photocured product of a bonding resin composition. The bonding resin composition includes: modified epoxy acrylate, a photoinitiator, a reactive diluent, and modified multi-walled carbon nanotubes. The modified epoxy acrylate is prepared by polymerizing a terminal hydroxyl intermediate obtained by reacting 4-hydroxy-3-trifluoromethylbenzaldehyde with 4-aminophenol with a silicon-containing epoxy intermediate to prepare a hyperbranched epoxy resin, which is then introduced into acrylic acid for reaction. The silicon-containing epoxy intermediate is prepared by reacting phenyltris(dimethylsiloxane)silane with allyl glycidyl ether. The modified multi-walled carbon nanotubes are prepared by chemically plating multi-walled carbon nanotubes with silver using the silver ammonia method. The fiber optic ribbon prepared by this invention has good mechanical properties, high temperature and high humidity resistance, antistatic properties, and flame retardancy.

The application belongs to the technical field of organic synthesis and polymer synthesis, and particularly relates to a synthesis method of 3,3'-dihydroxy azobenzene and hyperbranched azobenzene derived therefrom. The method uses 3-aminophenol as a starting material. Because phenol is unstable under oxidation conditions, the hydroxyl group is first protected by using a dimethyl tertiary butyl silyl group to obtain 3-(tertiary butyl dimethyl silyloxy) aniline. Then, under the catalysis of cuprous bromide, 3,3'-di(tertiary butyl dimethyl silyloxy) azobenzene is efficiently synthesized by using air as an oxidant. Finally, the silicon group protection of 3,3'-di(tertiary butyl dimethyl silyloxy) azobenzene is removed, and the target product with high purity is obtained through recrystallization purification. Then, the substitution reaction of 3,3'-dihydroxy azobenzene and N-Boc-bromoethylamine, the DBOC protection of the amino group, and the substitution reaction of the amino group and the active polybromide are performed to prepare hyperbranched azobenzene. The derivative has the advantages of novel structure and simple synthesis.

The invention discloses 4, 4 '-(perfluoropropane-2, 2-diyl) bis (2-((4-aminopyridine-2-yl) amino) phenol) and a preparation method and application thereof.The preparation method comprises the steps that 2-bromo-4-nitropyridine and 2, 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane serve as raw materials, condensation reaction is conducted, and an intermediate 4, 4'-(perfluoropropane-2, 2-diyl) bis (2-((4-aminopyridine-2-yl) amino) phenol) is obtained; the preparation method comprises the following steps: adding 4, 4 '-(perfluoropropane-2, 2-diyl) bis (2-((4-nitropyridine-2-yl) amino) phenol) into an intermediate, and reducing the intermediate under the action of a catalyst and hydrogen to obtain the 4, 4'-(perfluoropropane-2, 2-diyl) bis (2-((4-aminopyridine-2-yl) amino) phenol). The method is low in cost and simple and convenient to operate, the used solvent can be repeatedly recycled and reused, the obtained product is high in purity and yield, the dispersity and antistatic performance of the insoluble sulfur can be improved, and the method is more suitable for industrial production.

The polyamic acid composition contains the polyamic acid, an organic solvent, an aminophenol, and a methyl aminobenzoate. The polyamic acid includes a 4-aminophenyl-4-aminobenzoate residue as a diamine residue. The content of the 4-aminophenyl-4-aminobenzoate residue is 70 mol % or more with respect to the total amount of diamine residues included in the polyamic acid. The content of the aminophenol is 1 ppm by mass or more and 30 ppm by mass or less with respect to the total amount of the sample. The content of the methyl aminobenzoate is 0.01 ppm by mass or more and 0.10 ppm by mass or less with respect to the total amount of the sample. The contents of aminophenol and methyl aminobenzoate are obtained by gas chromatography-mass spectrometry using a sample obtained by diluting the polyamic acid composition so that the concentration of the polyamic acid is 1 mass %.

This invention discloses a modified polyester material for high-strength fabrics and its preparation method, relating to the field of textile technology. The modified polyester material for high-strength fabrics comprises the following raw materials in parts by weight: 100-110 parts modified copolyester, 0.1-0.3 parts antioxidant, 0.5-1.5 parts carbodiimide, and 0.2-0.4 parts light stabilizer. The modified copolyester is obtained by copolymerizing terephthalic acid, ethylene glycol, and a chain extender. The chain extender is prepared by cross-dehydrogenation coupling reaction of p-aminophenol and diethyl phosphite to obtain a flame-retardant monomer, followed by Michael addition of the flame-retardant monomer with sodium vinyl sulfonate to obtain a hygroscopic monomer, and then ring-opening esterification of the hygroscopic monomer with 2,3,6,7-naphthalenetetracarboxylic dianhydride.

The invention relates to a photo-initiated synthetic aminophenol compound method and application, and belongs to the technical field of organic synthesis. The synthesis method comprises the following steps: deprotonating a 1-hydroxybenzotriazole compound under an alkaline condition, and carrying out cracking reaction under the excitation of visible light to generate a high-activity biradical intermediate which is unstable and can be rapidly tautomerized into a more stable nitrosobenzene anion intermediate; the intermediate further reacts with cyclohexenone substances to synthesize the aminophenol derivative in one step. The method is simple and efficient, simple and convenient to operate, free of transition metal and additional oxidizing agents, simple and easily available in raw material reagent, high in product yield and capable of realizing large-scale synthesis, and a new method is provided for rapidly synthesizing the aminophenol compound. The synthesized aminophenol compound has good antibacterial activity, and especially has huge potential in the aspect of preventing and treating anthracnose of tea trees.