Abstract: An atmospheric pressure process for the continuous production of polyester is disclosed wherein a melt of dihydroxy ethyl terphthalate, or its low molecular oligomers, obtained by esterifying terephthalic acid or transesterifying dimethyl terephthalate with ethylene glycol, is intimately contacted with an inert gas to facilitate polymerization and removal of the reaction by-products. The ethylene glycol evolved and the inert gas are recycled.

Abstract: A treatment method for polyene resins used in thiol-ene formulations, especially norbornene resins, significantly stabilizes thiol-ene compositions made from batches of polyene resin which otherwise give compositions with poor dark stability. The treatment comprises contacting the polyene with an amphoteric treating agent selected from the group consisting of silicated magnesium oxide, basic aluminum oxide, silica gel, magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, barium oxide, and barium hydroxide, and then separating the resin from the treating agent prior to mixture with a polythiol to form a thiol-ene composition. The treatment method significantly reduces ionic content in polyene resins, particularly chloride ion but also sodium and potassium ions. Consequently, treatment is also beneficial with polyene resins which do not produce substantial dark stability problems.

Abstract: A process for producing high molecular weight polyester is provided which allows the production of small quantities of very high molecular weight polyester in a commercially convenient manner, comprising:polycondensing an aromatic dicarboxylic acid with a mixture of an alkanediol and an alkenediol in the presence of a catalyst and in the substatial absence of oxygen, up to a viscosity number in the range from 50 to 140 cm.sup.3 /g to obtain a polyester,contacting said polyester with 0.001 to 8% by weight of an agent which forms free radicals and dissociates with a half-life of 5 seconds to 120 minutes at temperatures in the range from 130.degree. to 350.degree. C., andreacting said polyester and said agent which forms free radicals to provide the high molecular weight polyester.

Abstract: A process for recycling polyester contained in waste materials is provided. The polyester is converted into ethylene glycol and terephthalic acid. The process steps generally include first combining materials containing polyester with an alkaline solution to form a slurry. The slurry is heated, causing ethylene glycol to evaporate which can then be collected. The remaining product stream is then mixed with water and filtered to remove any undissolved impurities. The aqueous filtrate can be acidified causing terephthalic acid to precipitate. Further, if silver is contained within the materials fed to the process, the silver can also be isolated and recovered.

Abstract: A method for removing oligomers and non-polymeric impurities from poly(arylene sulfide) polymers and producing the polymers in easily recoverable granular form is provided in which a poly(arylene sulfide) polymer associated with oligomers and non-polymeric impurities is contacted with a solvent, water, and optionally, a base, at a sufficient temperature to substantially dissolve the polymer, oligomers and impurities; then the solution is cooled to a temperature at which the poly(arylene sulfide) precipitates while oligomers and impurities remain in solution, then the precipitated polymer is separated from the solution containing the oligomers and impurities. A polymer product produced by this method is also disclosed.

Abstract: A treatment method for polythiol compounds used in thiol-ene formulations, especially formulations employing norbornene resins, significantly improves cure speed retention on aging of thiol-ene formulations which include hydroxylamine salts, such as N-nitrosoarylhydroxylamine aluminum salts, as shelf-life stabilizers. The treatment comprises contacting the polythiol with an amphoteric treating agent selected from the group consisting of silicated magnesium oxide, magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, barium oxide, and barium hydroxide, and then separating the resin from the treating agent prior to mixture with a polyene to form a thiol-ene composition. In formulations employing phenolic compounds having an alkenyl group in conjugation with the phenyl group thereof as shelf-life co-stabilizers the treatment method also significantly enhances the shelf-life stability of the formulation compared to formulations made from untreated polythiol.

Abstract: The present invention relates to polyesters which are particularly suitable in coating compositions which are sprayed with compressed fluids which act as viscosity reducing diluents.

Abstract: An aqueous phenol-formaldehyde resin solution with formaldehyde-phenol mol ratio in the range of 1.8 to 2.8, polymerization catalyst of 3% to 9% by weight, measured as NaOH equivalent, with less than 1% by weight potassium hydroxide, and about 0.1% to about 0.75% by weight potassium carbonate added after the catalytically-activated polymerization reaction has subsided while the resin is both soluble and fusible ("A" resol stage). Adhesive binders exhibit tolerance for variables in veneer moisture content from 0% to around 25% and in production timing from delivery of the veneer for assembly to curing of around 10 minutes to about 2 hours without significant degradation of bonding quality.

Abstract: Ester bonds are hydrolyzed in the conversion of substantially amorphous polyesters to their monomeric components, by being contacted with a mixture of (a) an alcohol, such as methanol, or glycol, (b) a polar aprotic solvent such as N-methyl-pyrrolidone or dimethyl sulfoxide and (c) an alkoxide or hydroxide such as sodium hydroxide.

Abstract: A process for the preparation of aromatic polyamide pulp having excellent properties comprising:a) preparing a polymerization solvent by adding a Lewis acid type compound to an amide type organic solvent, an urea type organic solvent or a mixture thereof;b) obtaining an anisotropic liquid crystalline polymer solution prior to gelation by dissolving an aromatic diamine in the prepared polymerization solvent and adding an aromatic diacid chloride to the solution, and effecting the polymerization thereof;c) maintaining the polymer solution at a predetermined temperature for a predetermined period; andd) separating the polymerization solvent and pulverizing the polymer by pulping machine.

Abstract: Novel ionomers of normally solid, thermo-plastic, orientable, copolymers of ethylene and at least one alpha,beta-ethylenically-unsaturated carboxylic acid having a relatively high content of the carboxylic acid are prepared under conditions whereby the copolymers are essentially solubilized in a strong base and contacted with at least one compound which contains ionomer-forming cations. One of the preferred polymers is an ethylene/acrylic acid copolymer. The so-formed ionomers are useful as materials for constructing various items and articles.

Abstract: A process for preparing an impact resistant resin, which comprises a step of graft copolymerizing a monomer mixture comprising an aromatic vinyl monomer and a monomer copolymerizable therewith, to a butadiene rubber-like polymeric latex in the presence of a redox polymerization initiator; a step of coagulating the resulting graft copolymer latex by mixing an antioxidant thereto and adding an alkaline earth metal salt thereto; and a step of washing the coagulated product by a washing water having the pH adjusted to a level of at most 7.

Abstract: A polyoxymethylene copolymer excellent in stability and mechanical properties which is comprised of oxymethylene units and oxyalkylene units and has a molecular weight of 10,000 to 200,000. The proportion of oxyalkylene units to oxymethylene units is 0.07 to 0.5% by mole and the ratio of the absorbance of terminal formate groups to that of methylene groups determined by infrared spectrophotometry is not more than 0.025. A process for producing the copolymer is also disclosed.

Abstract: Alumina-based adsorbents containing at least one compound of an alkali or alkaline earth metal, wherein the alkali or alkaline earth metal values are present in an amount ranging from 15 mmole to 100 mmole per 100 g of alumina, are useful for the adsorptive purification of polyolefins prepared by the polymerization of olefins in the presence of a metallic coordination catalyst, to remove contaminating catalyst metal values therefrom with but negligible monomer/solvent isomerization.

Abstract: A process is disclosed for improving the water-whitening resistance of a pressure sensitive adhesive containing an aqueous latex emulsion and water-soluble ions by removing the water-soluble ions and adjusting the pH of the pressure sensitive adhesive formulation to at least about 6.0. The preferred method of removing the water-soluble ions is to contact either the aqueous latex emulsion, the formulated pressure sensitive adhesive containing the aqueous latex emulsion, or both with ion exchange resin. The product produced by the process is also disclosed.

Abstract: A method is provided for the production of poly(arylene sulfide) compositions comprisinga) contacting under suitable conditions a sulfur source, a dihalogenated aromatic compound and optionally other halogenated aromatic compounds, a polar organic compound, a base, and an alkali metal carboxylate in order to form a substantially liquid mixture comprising poly(arylene sulfide) polymer, polar organic compound and water;b) slowly cooling to form a slurry comprising solid poly(arylene sulfide) particles and liquid comprising the polar organic compound and water and adding an effective amount of at least one extraction agent;c) contacting the poly(arylene sulfide) particles with an aqueous solution containing calcium ions; andd) recovering the poly(arylene sulfide) composition.The poly(arylene sulfide) compositions prepared according to the invention method are especially useful for the preparation of fibers and monofilaments.

Abstract: This invention relates to a process for the crosslinking of polymers containing diaryl ketone groups consisting of heating the polymer with an alcohol and/or alkoxide, and optionally exposing the polymer to a strong mineral acid. The crosslinked polymers have enhanced chemical resistance.

Abstract: A clinically-acceptable hydrophilic silicone-based soft gas permeable contact lens produced by subjecting the lens material to extraction with a hydrophilic, polar group-containing, organic solvent followed by replacement of the organic solvent with a physiological saline solution.

Abstract: This invention relates to a process which significantly reduces the time for hydrolyzing a crosslinked maleic anhydride/lower alkyl vinyl ether copolymer to a clear gel which comprises suspending or dispersing fine granules of the crosslinked copolymer in deionized water and agitating the resulting dispersion or suspension for a period of between about 15 and about 130 minutes at a temperature of from about 60.degree. to about 90.degree. C. and then cooling the hydrolyzed mixture before introducing a basic neutralizing agent at a temperature of from about 15.degree. to about 85.degree. C. to produce a clear, homogeneous hydrolyzed gel having a Brookfield viscosity of from 5,000 to 250,000 cps.

Abstract: This invention reveals a process for recovering polyethylene terephthalate flakes from a recycle stream containing polyethylene terephthalate flakes and polyvinyl chloride flakes which comprises: (1) treating the recycle stream with (a) at least one inorganic base selected from the group consisting of sodium hydroxide and potassium hydroxide and (b) at least one nonionic surfactant under conditions and for a time sufficient to decrease the contact angle of the polyethylene terephthalate flakes with water below a value of 25.degree. while maintaining the contact angle of the polyvinyl chloride flakes above a value of about 45.degree.

Abstract: Cyclic polyoxymethylene having a number-average molecular weight of 500 to 5,000 is obtained by solid state cyclization reaction of an alkalidegradative linear oxymethylene homopolymer in the presence of a medium containing a cationic catalyst.The cyclization is effected at 10.degree. to 150.degree. C. for 1 to 500 minutes in an organic liquid medium.The reaction mixture obtained by the cyclization is treated with an alkaline medium to hydrolyze and remove away unreacted linear polyoxymethylene homopolymer, and isolate the cyclic polyoxymethylene.The product has a sharp molecular weight distribution and is useful as a resin improver.

Abstract: A method for purifying an ethylene-.alpha.-olefin olefin having at least 3 carbon atoms, or ethylene with an .alpha.-olefin having at least 3 carbon atoms and a nonconjugated diene compound, in a hydrocarbon solvent in the presence of a catalyst comprising a vanadium compound, an organoaluminum compound, and a halogenated ester compound, the method including a step of mixing and stirring the polymerization reaction mixture obtained by the polymerization reaction in an aqueous alkaline solution in such an amount as to give an aqueous phase having a pH of not lower than 10.0 after mixing and stirring, is disclosed. A method for purifying an ethylene-.alpha.-olefin copolymer is also disclosed, including a step of an oxidation treatment of the polymerization reaction mixture in an aqueous alkaline solution in such an amount as to give an aqueous phase having a pH of not lower than 10.0 after the oxidation treatment.

Abstract: Novel modified polymeric materials are provided. The polymeric materials according to the invention are prepared by grafting a fluorine-containing compound onto a polyurethane polymeric substrate. The polymeric materials show superior blood compatibility in the in vitro and ex vivo tests, attributing to hydrophobic property, inertness and water-repelling property intrinsic to the grafted fluorine containing compounds.The polymeric materials according to the invention are useful as the materials for the artificial, circulatory, internal organ systems to be contacted with blood, such as artificial hearts, artificial blood vessels, artificial heart valves, artificial blood oxygenators, and artificial kidneys, or for the medical devices/instruments to be inserted into the blood vessels, such as vein catheters, artery catheters and intra-aortic balloon pumps.

Abstract: A process for the precipitation of aqueous plastics dispersions containing polyvinyl alcohol, preferably from waste waters, and separation of the polymeric solids content, which comprises adding the following to the dispersion in order, with thorough mixing:a) a boric acid component,b) a basic compound for making the pH alkaline, thenc) an iron salt andd) a cationic polymeric polyelectrolyte, and isolating the precipitate which forms in the alkaline medium. The process according to the invention is advantageously applicable in all relevant sectors of technology and waste water treatment in which polymer dispersions containing polyvinyl alcohol are used or have to be disposed of, and where waste waters in which dispersions containing polyvinyl alcohol are present have to be processed. Degrees of clarification of more than 95% can be achieved.

Abstract: This invention relates to obtaining beta crystalline Phase isotactic polypropylene with high purity and thermal stability simply by melt-crystallization in the presence of a two component beta nucleating agent. The two component beta-nucleating agent is formed by mixing 0.0001-1 weight % of dibasic acid with 0.001-1 weight % oxide, hydroxide or acid salt of a Group IIA metal. Such beta phase polypropylene can be used for the production of high impact strength molding extrusion shapes, microporous film and microporous hollow fiber.

Abstract: An alcohol based, water soluble binder composition for nonwoven material made from water swellable, water soluble or water sensitive fibers and related substances is provided comprising a substantially anhydrous solution of an acrylic polymeric resin, and an alcohol diluent. The water soluble binder composition effectively binds water swellable, water soluble or water sensitive fibers into a nonwoven material such as a fabric; the nonwoven material comprising a nonwoven web of a water swellable, soluble or sensitive fiber component.

Abstract: A method for the stabilization and isolation of a fluoropolymer bearing carboxylic acid (--CO.sub.2 H) groups and prepared as an aqueous dispersion using a dispersion polymerization process which employs a dispersing agent whose dispersion-stabilizing effect is removable by heating the dispersion and an initiator (or initiator system) which yields carboxylic acid groups on the fluoropolymer, which method comprises, after preparing an aqueous dispersion of the fluoropolymer using dispersion polymerization, converting the carboxylic acid groups on the fluoropolymer in the aqueous dispersion to carboxylate anion groups (--CO.sub.2 --) using a base and then heating the so-modified fluoropolymer dispersion to cause simultaneously:1) substantial removal of carboxylate anion groups, thereby to yield stable groups in their place, and2) isolation of the fluoropolymer from the dispersion by coagulation (agglomeration) of the fluoropolymer dispersion.

Abstract: Continuous process for removing unstable components from crude oxymethylene copolymer, which still contains catalysts, monomeric starting materials and unstable components, by treating the copolymer with deactivators, optionally in the presence of auxiliaries, in a pressure zone, and subsequently removing volatile components in a pressure-release zone in the presence or absence of stabilizers, in which process the crude polymer is fully melted in the absence of the deactivators and auxiliaries immediately after completion of the polymerization step, and the deactivators are subsequently incorporated, alone or together with auxiliaries, under pressure into the resultant polymer melt in at least one pressure zone.By this process, degradation is avoided and significantly better properties are obtained.

Abstract: A method of modifying a synthetic resin comprises treating a solution or dispersion of the synthetic resin containing water-soluble electrolytes as impurities is treated with basic or acidic, water-insoluble fine particles which have been purified and classified, whereby cations having origin in the electrolytes are fixed in the acidic fine particles or anions having origin in the electrolytes are fixed in the basic fine particles. Synthetic resins modified in accordance with the modification method are produced.

Abstract: Thermoplastics containing imide groups in the polymer backbone, soluble in an unmodified state, are rendered reactive with thermosetting resins by partial conversion of the polymer backbone to provide reactive groups. The modified polymer may be added as microspheres to a thermosetting resin, subsequently crosslinking therewith supressing solvent sensitivity in a fiber reinforced matrix composite comprising the toughened resin as the matrix therefore. The modified polymer microspheres retain their physical identity in the cured composite structure.

Abstract: Ionically crosslinked ethylene copolymers prepared by mixing a carboxyl-containing copolymer with an aqueous metal salt solution in the reaction zone of a twin-screw extruder and transferring the product to a devolatilization zone, and are used as adhesion promoters, injection molded articles or laminating films.

Abstract: A facile process for converting polyketones containing pendant functional groups to polyesters is provided. The process involves reacting the polyketone with an organic peroxyacid oxidizing agent in an inert liquid medium at a temperature from -20.degree. C. to 150.degree. C. to convert substantially all or only a portion of the keto functionality to ester moieties. The polyketones are obtained by copolymerizing carbon monoxide and a vinyl or vinylidene monomer having at least one functional group containing one or more oxygen, nitrogen, sulfur or halogen atoms.

Abstract: In the process of producing hydroxylated polybutadiene from a diene monomer in the presence of hydrogen peroxide and a solvent, wherein the solvent is recovered by distillation for reuse; after separation of the hydroxylated polybutadiene from mixture containing such solvent and reaction impurities, the improvement comprising subjecting said mixture to the action of an alkali metal hydroxide or a hydrazine prior to distillation.

Abstract: Process for the production and purification of SH-terminated prepolymers by reaction of polyhydroxy compounds with thioalkane carboxylic acids, wherein one or more adducts of ethylene oxide and/or propylene oxide with triols or tetraols corresponding to the following general formula ##STR1## in which m=1, 2 or 3,n=0, 1 or 2 andp=0 or 1,and having a molecular weight of from 400 to 10,000 are reacted with one or more thioalkane carboxylic acids corresponding to the following general formulaHS--R--COOH (II)in which R is a straight-chain or branched C.sub.1 -C.sub.

Abstract: Grinding agent for aqueous suspension of coarse mineral materials intended for pigment applications, composed of an alkaline acrylic polymer and/or copolymer, with an average specific viscosity of less than 0.8, formed of a fraction of this polymer and/or copolymer isolated by means of a polar solvent, the specific viscosity of said fraction comprised between 0.3 and 0.8.

Abstract: This invention relates to a method of producing a modified polyester having high fiber whiteness and satisfactory dyeability. In producing a polyester at least 80% of whose repeating structural units are ethylene terephthalate units, at least one specified polyalkylene glycol having a potassium and sodium content not more than 3 ppm and an average molecular weight not less than 400 is added for copolymerization. The method enables production of a polyester with a high degree of whiteness and, moreover, a polyester with excellent static-proofness and dyeability.

Abstract: Process for removing color-formers from polymeric sulfonated phenol-formaldehyde condensation products so as provide condensation products having reduced tendencies to turn yellow and which provide stain-resistance to polyamide textile substrates which comprises dissolving a polymeric sulfonated phenolformaldehyde condensation product in a aqueous base, acidifying the resulting aqueous solution so as to form a slurry, heating the slurry so as to form a two-phase system comprising an aqueous solution and a water-soluble taffy-like material, separating the aqueous solution and the water-insoluble material from one another, and dissolving the wate-insoluble material in an aqueous base.

Abstract: In a process for producing epoxy resin with low EHC-content there is added to a continuous flow of the chlorine-substituted starting material continuously, with all reaction parameters constant, a dehydrochlorinizing agent, e.g. NaOH, in an amount approximately the stoichiometrical equivalent of the predetermined EHC-content of the starting material. Ionically bound chlorine is removed from the epoxy resin. A stream of a bypassing portion of the epoxy resin is subjected continuously, with brief periodical interruptions, directly after removal of the ionically bound chlorine, to fluorescence-exciting X-ray irradiation and the total chlorine fluorescence is detected, thereby automatically continuously determining the total chlorine content.

Abstract: The instant invention deals with the alteration of solid synthetic polymers to improve the overall functional performance of the polymers. The invention also deals with a fast, clean, efficient, inexpensive method of altering the surface of textiles. The method comprises contacting a textile with a swelling agent and a base and heating to alter the textile, and then acidifying the treating bath and contacting the textile with an active substance, such as a hydrophilic polymer, to further alter the textile.

Abstract: Phenolic impurities are removed from polyaryloxyphosphazenes by extracting a solution of the crude polyaryloxyphosphazene with an aqueous lower alcohol alkali metal base solution such as aqueous methanolic sodium hydroxide.

Abstract: The present invention is directed to a continuous process which removes the 1 to 3% cyclic oligomers formed in the polycarbonate process and after hydrolysis of the oligomers recycles the resulting monomer for use in the reaction forming the polycarbonates. To remove the cyclic oligomers to a level so as to produce an improved polycarbonate product and to recover the oligomers in an economical manner for recycling in a continuous process, the selection of a solvent is unique and essential to achieve the continuous process. The solvent for the cyclic oligomers must be immiscible with water, must not react with an alkali and have a cohesive energy density of less than 90.

Abstract: The total halide content of epoxy resins is reduced by heating a resin containing undesirable halide dissolved in a solvent mixture containing at least one polar aprotic solvent in the presence of an alkali metal hydroxide for a time sufficient to reduce the total halide content.

Abstract: The invention features a lithographic composition fabricated from a process wherein an acidic novolak resin is neutralized in solution. The solution comprises a common compatible solvent with the other ingredients of the coating composition, such as a positive sensitizer, a color changing dye, and a light activated, acid-releasing compound.

Abstract: A method for stablizing organopolysiloxanes containing phosphonitrilic chlorides and/or their reaction products against viscosity changes by reacting the phosphorus compounds present in the organopolysiloxanes with at least one oxide, hydroxide or carbonate of a divalent or trivalent metal, and thereafter separating the solid from the organopolysiloxanes.

Abstract: A process of purifying maleic anhydride graft polyolefin comprising the steps of adding an aqueous solution of alkali initial hydroxide to a solution of maleic anhydride graft polyolefin containing unreacted maleic anhydride which is dissolved in an organic solvent at a temperature from 80.degree. C. to 160.degree. C., thereby precipitating maleic anhydride graft polyolefin particles to make a W/O emulsion; stirring the W/O emulsion while maintaining the temperature at a same temperature as above for less than 2 hours, thereby selectively forming the alkali metal salt of unreacted maleic anhydride; adding the aqueous solution of alkali metal hydroxide to the W/O emulsion to convert the W/O emulsion into an O/W emulsion; separating the maleic anhydride draft polyolefin particles, and washing the maleic anhydride graft polyolefin particles with water.

Abstract: To reduce the content of hydrolyzable chlorine in glycidyl compounds, these are dissolved in a halogen-free organic solvent and treated with an equivalent excess of aqueous alkali metal hydroxide solution at elevated temperature, the excess being 100 to 200% of the equivalent amount theoretically required for complete dehydrochlorination of the hydrolyzable chlorine, the water is then removed from the organic solution, the organic solution is treated with 5 to 500 times the amount, based on the amount of alkali metal hydroxide employed, of moist cellulose containing up to 35% by weight of water at elevated temperature and, after filtration, the glycidyl compound is isolated from the organic solution.

Abstract: A polybutylene terephthalate is manufactured by the steps of polycondensating in the liquid phase terephthalic acid or a lower alcohol ester thereof as the acid component and 1,4-butanediol as the diol component to obtain a prepolymer of polybutylene terephthalate, solidifying the prepolymer and further polymerizing the prepolymer in the solid phase to obtain a polybutylene terephthalate of a higher polymerization degree, 0.001 to 5 percent by weight, based on the prepolymer, of a nucleator being added to the polymerization mixture at any time during a period of from the monomer-mixing stage before the starting of the solid phase polymerization, the solid phase polymerization being conducted in the presence of the nucleator uniformly dispersed in the polymerization mixture. The solid polymerization can be treated subsequently to the liquid polymerization and can proceed in a short time.

Abstract: A polymer layer of polyester or polyvinyl chloride is recovered from a multilayered scrap or waste chip material by contacting the chip material with an aqueous solution containing a base metal hydroxide and a reagent selected from the group consisting of a salt, an amine, and an oxidizing agent. The removal process is accelerated by using, either singularly or in combination, an alkyl dimethyl benzyl ammonium chloride, heat, or agitation. Thereafter the polymer layer is isolated and recovered.

Abstract: Degradation of body-waste bags to assist disposal thereof in sewage systems is facilitated by addition of a base to raise the pH of the human fecal waste bag contents to at least about 12. Inter alia, there is provided a package of at least one bag and sufficient base, preferably in prepacked quantities, to treat all the bags in the package.

Abstract: The invention relates to a simplified, economic process for the production of polyamines by the alkaline hydrolysis of compounds containing terminal aromatic and/or aliphatic isocyanate groups (including modified isocyanates or NCO-prepolymers and semi-prepolymers with NCO-contents of from 0.5 to 40% by weight), with strong aqueous bases, direct isolation of the polyamines from the carbamate stage being possible by thermal carbamate decomposition and/or solvent extraction.The invention also relates to the use of the aromatic and/or aliphatic polyamines containing primary NH.sub.2 -groups obtainable by the process according to the invention for the production of polyurethanes, such as optionally cellular polyurethane plastics and polyurethane foams.