Abstract: A test method and device are described for quantitatively determining the presence and concentration of chlorine dioxide in aqueous solution, which may contain chlorine. Contacting the aqueous solution containing chlorine dioxide with a test strip in accordance with the invention produces a color change in proportion to the concentration of the chlorine dioxide. The invention has particular utility in determining the presence of chlorine dioxide in water containing chlorine such as municipal water.

Abstract: This invention is in the field of toxicology and clinical diagnostics. More specifically, this invention provides a single dry chemistry, liquid chemistry, or lateral flow dry chemistry combination test device for use in the detection of adulteration by the addition of bromine(s) to a specimen submitted for Drugs of Abuse (DAU) testing and clinical diagnostic purposes in aqueous fluids, including urine, saliva, serum, blood, sweat extracts, and liquid homogenates of hair.

Abstract: A method for removing one or more fluorinated alkenes from a fluid comprises the step of contacting the fluid with an N-, S-, or P-containing nucleophile for a time sufficient to form an N-, S-, or P-containing nucleophile-fluoroalkene adduct. The nucleophile, and therefore the adduct, can be covalently bonded, coated or sorbed to a particulate support which can be enmeshed in a porous, fibrous web. In a preferred embodiment the fluorinated alkene can have the formula wherein A=F or Rf; X=H, F, Cl, Rf, or YRf; Z= H, F, Cl, or Rf; and Y=O, N, or S; with the proviso that at least one A=F, and at most one of Z and X is H; wherein each Rf is independently selected from the group consisting of highly fluorinated or perfluorinated alkyl groups; and a combination of any two Rf groups can be linked to form a cyclic structure. The Rf alkyl chains may contain from 1-20 carbon atoms, with 1-12 carbon atoms preferred.

Abstract: This invention is in the field of toxicology and clinical diagnostics. More specifically, this invention provides a single dry chemistry, liquid chemistry, or lateral flow dry chemistry combination test device for use in the detection of adulteration by the addition of bromine(s) to a specimen submitted for Drugs of Abuse (DAU) testing and clinical diagnostic purposes in aqueous fluids, including urine, saliva, serum, blood, sweat extracts, and liquid homogenates of hair.

Abstract: The present invention provides a method of detecting trace anions in solutions at a parts per billion (ppb) concentration level or less using existing anion detection technology, by employing a novel sample preparation method conducted prior to injection into a detection unit. The method includes the steps of: adding a precipitant to at least a portion of the solution; evaporating the solution, whereby a trace anion-rich solution is formed; and detecting the level of the trace anions in the trace anion-rich solution to at least a ppb concentration level. As such, any existing detection unit designed for measuring anions, known to those skilled in the art, can be used without modification. This results in a cost and time effective method of detecting trace anions in solution at a ppb concentration level. The invention also provides a system for effectuating the novel method of the present invention.

Abstract: A method for directly monitoring and controlling a continuous process stream for dechlorination residual is provided. A sample stream to which a dechlorination agent has been added to completely eliminate a residual disinfectant is continuously drawn off. An analyzing agent of iodine is provided by introducing an iodide solution, a chloramine-T solution, and an acetic acid buffer into the sample stream. The reagents quickly react to produce iodine that reacts with any residual disinfectant removal agent residual that may be present. Thereafter, the sample stream is continuously analyzed to determine the amount of unreacted iodine remaining in the process sample. Based on the amount of iodine added to the process sample and the amount of unreacted iodine remaining in the sample after reaction, the amount of dechlorination residual is continuously determined.

Abstract: Methods for detecting chloral hydrate in dichloroacetic acid are described.

Abstract: The invention relates to multicomponent test systems which indicate the concentration of one or more analytes in a liquid sample, as well as the effect of action on the sample which results in an increase or decrease of the concentration of the analyte under consideration. Simulating increase or decrease permits the user to determine if corrective action is necessary, and what that corrective action might be. Both dry chemistry and wet chemistry systems are described.

Abstract: The present invention relates to a method and to a device for sensing low levels of iodine in an aqueous solution by using an extraction procedure whereby iodine from the aqueous solution is extracted into a substantially water-insoluble organic phase, and testing measuring the concentration of iodine in the organic phase using optical absorption techniques. The measured concentration of iodine can then be equated with concentration of iodine or iodine in the aqueous solution.

Abstract: An optical-chemical sensor which is suitable for the continuous and discontinuous determination by luminescence optics of the concentration of chloride in an aqueous sample and which comprises a luminescence indicator (I) and a polymer (H) carrying the luminescence indicator (I) is characterized in that the luminescence indicator (I) is a non-lipophile acridine or bisacridine compound and the polymer (H) is a linear-chain hydrophile polymer soluble in an organic solvent, whereby it is possible to excite the sensor by commercially available LEDs, to manufacture very large numbers thereof at a moderate cost and in a reproducible way and, preferably, to use it for the determination of physiological chloride concentrations and the sensor furthermore has a wide dynamic measuring range for the determination of chloride; a high sensitivity, stability and reproducibility; a high selectivity for chloride; and a low pH cross-sensitivity.

Abstract: Amounts of components in a specimen can be analyzed with excellent quantitativity. The analysis includes: measuring an amount of a component to be analyzed in a specimen; measuring an amount of a standard component present originally and homeostatically in the specimen other than the component to be analyzed; determining the amount of the specimen from the amount of the standard component thus measured and a known concentration of the standard component in the specimen; and determining a concentration of the component to be analyzed in the specimen from the amount of the specimen thus determined and the amount of the component to be analyzed thus measured. The quantitative analysis of the present invention allows a component to be analyzed to be measured with high quantitativity as shown in FIG. 1.

Abstract: A method and apparatus for automatically calculating and controlling levels of a given chemical in a liquid from a liquid reservoir using colorimetry testing, the method comprising the steps of (i) collecting in an optical chamber a sample of liquid from a liquid reservoir; (ii) taking a calibration colorimetry A reading of the liquid sample, whereby a reference voltage value B representative of an acceptable limit of a known chemical is calculated and stored in a memory of a controller unit; (iii) releasing the liquid sample from the optical chamber; (iv) collecting in the optical chamber a further sample of liquid from the liquid reservoir; (v) adding a predetermined quantity of a reagent to the further sample in the optical chamber, the reagent chosen as having properties making it react to the presence of the known chemical present or to be added to the liquid; (vi) taking a test colorimetry reading C of the further sample with the reagent added thereto and obtaining a voltage signal representative thereo

Abstract: A method is described for precisely controlling chlorination of wastewater and chloramination of drinking water. The method involves analyzing the water for the presence of residual monochloramine without interference of dichloramine, organic amines, organic chloramines or nitrites. A color-forming reagent is added to a sample of the water which will develop a colored compound upon reaction with monochloramine, after which the sample may be colorimetrically analyzed to determine the amount of monochloramine present. The method is very accurate and avoids the problems associated with conventional tests used for chlorination control.

Abstract: A test method and device are described for quantitatively determining the presence and concentration of monopersulfate ion in aqueous solution. Contacting the aqueous solution containing monopersulfate ion with a test strip in accordance with the invention produces a color change in proportion to the concentration of the ion. The invention has particular utility in maintaining the proper level of sanitizers in swimming pool water.

Abstract: The present invention is directed to tracer-containing chemical compositions and to the use of at least one perfluorocarbon tracer in such compositions to provide a means of identifying and quantitatively analyzing such compositions.

Abstract: This invention relates generally to a method for the extraction of organic liquid contaminates from a sample. This invention is directed to the ability of hydrophobic extraction material or ribbon tape made of a hydrophobic polymer to facilitate the extraction of liquid organic contaminates from an aqueous sample in contact with an organic non-polar solvent.

Abstract: An improved test is described for chlorine in pool and spa water where potassium monopersulfate is used as an oxidizing agent and DPD is used as an indicator. N,N-bis(hydroxyethyl)-2-aminoethane sulfonic acid or bicine is used to mask or eliminate the potassium monopersulfate so that it does not interfere with the DPD indicator. The test is very reliable and accurate.

Abstract: A process for extracting inorganic ionic contaminants from a front surface of a silicon wafer for chemical analysis. The wafer is placed in a container upon a support which holds the wafer in a generally level orientation and isolates the wafer to inhibit air circulation over the front surface. Air circulation can introduce contaminants to the extraction fluid, causing a false measurement of contaminants on the wafer. A layer of extraction fluid is deposited upon only the front surface of the wafer and held for a period of time so that contaminants on the front surface are extracted into the layer of fluid. A portion of the layer of fluid is collected by a sampling device for subsequent analysis.

Abstract: A method for determining constituents in water, in particular the content of organic carbon and/or nitrogen, in which an aqueous sample is evaporated and combusted in at least one heating vessel (154a) provided with a heater (154), and the combustion product is delivered in a transporting gas stream to a detector (142) for determining the concentration of a gaseous compound of the constituent, wherein the heating vessel, or a first heating vessel, at the instant of delivery of the aqueous sample has a temperature below or at most within the range of the boiling temperature of the sample, and after delivery of the sample the temperature is increased, wherein the sample is heated by one and the same heater in a first step from an outset temperature below the boiling temperature to an evaporation temperature, and in a second step to a substantially higher temperature, and the combustion product is kept in closed circulation during the analysis.

Abstract: An on-site monitor is disclosed for providing automatic measurements of chemical concentrations in a liquid or gaseous environment. The opto-electronic monitor has an extended probe, which can be inserted into the liquid or to be in contact with the ambiance, comprising a indicator chamber for continuously supplying fresh indicator material, a light source, and a detector. The light source and the detector are either embodied outside of liquid or into the extended plastic probe inside the liquid. A delivery unit, which is activated by a timer, delivers a small amount of indicator material into the liquid or a sampling cavity. The indicator material reacts with the ions in the liquid automatically. The light source has a wavelength which matches with the indicator's absorption wavelength and the detector measures the transmission (or reflection) through the indicator material or solution.

Abstract: The present invention is directed to a method for determining the halogen toxicity level in a sample containing halogenated compounds, specifically halogen containing rubbers by utilizing thermal electrons formed inside a mass spectrometer operated at negative ion electron capture conditions. The method allows for detection of the toxic species from the parts per million level, down to the parts per billion levels.

Abstract: A sensitive and convenient unitized method, reagent composition and test device is presented for the determination of free halogens in aqueous test fluid samples. The reagent composition basically consists of an azine type indicator material and an effective amount of a benzidine type catalytic material, the combination of two materials preferably being impregnated into a matrix material for ease of handling and use.

Abstract: A method for determining total chlorine amount present in a sample by mixing the sample with a benzidine indicator solution comprising a benzidine compound capable of forming a dye by a reaction with a chlorine, wherein the hue of the formed dye changes depending upon the mole ratio of the chlorine to benzidine compound and determining the total chlorine amount from the hue. A kit for practicing the method incudes the indicator and a color scale for the hues of the dye.

Abstract: A process for the extraction and purification of TCDD (2,3,7,8-Tetrachlorodibenzo-p-dioxin) from a sample matrix. The process of the present invention overcomes a problem of prior art processes for extracting TCDD, by providing for chemical destruction of potentially interfering components in a sample matrix making the steam distillation of TCDD possible. A typical sample matrix comprises blood serum.

Abstract: A system for detecting organic contaminants in water supplies. A sampling unit is employed which includes a housing having at least one opening therein and a tubular member positioned within the housing having a central passageway surrounded by a side wall. The side wall is made of a composition designed to absorb the contaminants. In use, the sampling unit is immersed in a water supply. The water supply contacts the tubular member through the opening in the housing, with any contaminants being absorbed into the side wall of the tubular member. A carrier gas is then passed through the central passageway of the tubular member. The contaminants will diffuse out of the side wall and into the central passageway where they will subsequently combine with the carrier gas, thereby yielding a gaseous product. The gaseous product is then analyzed to determine the amount and type of contaminants therein.

Abstract: A method for the determination of iodide in aqueous solutions, preferably in urine. The process is characterized in that the sample solution is admixed with a chromogen and a peracid solution and the color reaction is evaluated visually or photometrically. In the determination of iodide in urine, the sample is pretreated by means of a purified activated carbon.

Abstract: A composition, method, and test device for determining the total available chlorine concentration, and the relative amounts of free and bound chlorine, of a test sample are disclosed. The test device includes a test pad having a suitable carrier matrix incorporating an indicator reagent composition capable of converting combined available chlorine to free available chlorine and of interacting with free available chlorine to produce a detectable and measurable response for total available chlorine over a range of 0 to over 5000 ppm total available chlorine in the test sample. An indicator reagent composition contains: (a) an indicator dye that is responsive to free available chlorine, such as tetramethylbenzidine, (b) a buffer, (c) a surfactant, (d) an optional catalyst, and (e) an optional polymer.

Abstract: A method for determining the amount of residual disinfectant removing agent in a process stream to which the disinfectant removing agent has been added to completely remove a disinfectant residual, comprising the steps of: (a) drawing off a sample of the process stream; (b) mixing an acidic iodate solution and an iodide solution to produce an iodine analyzing agent; (c) adding to the sample the iodine analyzing agent in an amount sufficient to react with the residual disinfectant removing agent and leave an unreacted amount of residual iodine; (d) allowing sufficient time for the iodine to react with the residual disinfectant removing agent; (e) analyzing the sample to determine the amount of residual iodine remaining in the sample, and (f) determining the amount of residual disinfectant removing agent in the sample based on the amount of iodine analyzing agent added and the amount of residual iodine remaining in the sample after reaction.

Abstract: A method and apparatus is provided for real-time detection of trace amounts of atmospheric and tropospheric halogen-containing compounds. The present invention can be used either for in situ detection or remote sensing. A laser is employed to induce photofragmentation of the halogenated molecules and facilitate detection of the characteristic atom fragment by stimulated emission spectrometry. For brominated compounds, the output of a single laser is tuned to the strong two-photon 4p.sup.4 5p .sup.4 D.degree..sub.3/2 .rarw.4p.sup.5 2 P.degree..sub.3/2 transition of Br at 260.634 nm. The Br atoms are subsequently detected by stimulated emission (SE) via the 4p.sup.4 5p .sup.4 D.degree..sub.3/2 .fwdarw.4p.sup.4 5s .sup.4 P.sub.5/2 transition at 844 nm. For comparison, the laser-induced fluorescence (LIF) signal at the same wavelength is also monitored. The SE signal is distinct from the fluorescence in that it is coherent, bidirectional, and propagates coaxially with the laser beam.

Abstract: Colorimetric methods for determination of residual chlorine, free and combined, in water are described which comprise the use of 3,3',5,5'-tetramethylbenzidine (TMB), as well as methods and kits for determining chlorine in water by visual comparison which comprise, apart from TMB, a calibration scale. The basis for the preparation of one of the kits (or the kit described as an example) lies in the orange color that is produced by means of the reaction between chlorine and TMB, which permits a straightforward determination of residual chlorine by means of a simple visual comparison with a graduated, stable scale that is constituted either by solutions of Tropaeolin O of different concentrations or, alternatively, by a printed scale on plastic material or paper, by etching.

Abstract: The process includes the steps of: a) contacting a liquid containing mRNA with an insoluble support having DNA probes attached thereto via the 5' -terminus thereof whereby the MRNA is hybridized to said probes and hence to said support; b) removing said liquid; and c) adding enzymes and nucleotides in solution whereby the probe functions as a primer to produce single stranded cDNA on the mRNA probe. The probe DNA may be oligo-dT or a specific DNA sequence, such as one that is complementary to a conserved region in a class of mRNA molecules. The insoluble support comprises magnetic particles which are monodisperse polymer particles comprising superparamagnetic iron oxide, a coating to reduce non-specific binding and a substituent for attaching an oligonucleotide.

Abstract: Provided is a fluorometric analytical method for detecting chloride ion in a sample by quenching of fluorescence of a fluorescent dye, the fluorescent dye being one of 3,6-bis(dimethylamino)acridine and a derivative thereof of the formulae ##STR1## wherein R is alkyl having 1 to 30 carbon atoms, and X.sup.- is a halogen ion.

Abstract: An apparatus and method for monitoring the product quality of chlorine in which a sample stream of chlorine is taken from a chlorine stream and a portion of the sample stream is passed to one of three different analyzers for detection of various contaminants. A common data acquisition network receives data from each analyzer for integration and output. The analyzers include a bromine in chlorine analyzer, a non-condensable gas in chlorine analyzer, and a halocarbon in chlorine analyzer.

Abstract: A chloride analyzer includes an inlet valve and filters for process water to be analyzed, as well as a pH electrode to verify the pH value of the incoming liquid before further treatment. A stripper bubbles stripping air through the process water to remove hydrocarbons and hydrogen sulfide therefrom, and the discharge line from said stripper feeds a reaction vessel to which also reagent from a supply vessel is passed. After a suitable reaction time, optionally followed by a further air stripping operation through air supply line, the reaction products are fed via line to an ionometry measuring cell where chloride analysis is carried out using a specific ion selective electrode.

Abstract: A process for the measurement of the level of radioactivity of a solid by contacting the solid with a chemically stable reactant fluid. The reactant fluid is converted by nuclear radiation to a chemically stable product fluid to an extent dependent upon the radioactive content of the solid. The amount of the reactant fluid converted into the product fluid is detected in order to determine the level of radioactivity of the solid.

Abstract: Selected polyvalent anions or cations are removed from a liquid sample stream as a pretreatment for the analysis of the liquid sample stream. A stream containing anions of interest, precipitable anions (e.g. sulfate ions) to be removed and an added displacing salt flow through a first cation exchange resin bed having precipitable exchangeable polyvalent ions (e.g. barium ions). Displacing polyvalent cation (e.g. calcium) displaces the exchangeable polyvalent ion from the cation exchange resin into the liquid sample at sufficient concentration to cause the precipitable anion and exchangeable cation to form a precipitate which remains in the resin bed and is thus is removed from the sample stream. Then the anions of interest in the soluble portion of the liquid sample stream are separated and detected. The invention is also applicable to the removal of precipitable cations (e.g. barium ions) by reversing the roles of the anions and cations.

Abstract: Methods for the detection, identification and/or quantitation of halogenated hydrocarbons in aqueous samples and kits for performing the methods are provided which provide high sensitivity and can provide high selectively for individual halogenated hydrocarbons such as TCE or THMs. An additional method is provided for the sensitive determination of TTHM in an aqueous sample. These methods use a general two step procedure of (1) extracting and concentrating the halogenated hydrocarbons from the aqueous sample and (2) subjecting the concentrated halogenated hydrocarbons to a modified Fujiwara reaction to provide chromophoric products which can be analyzed by absorption spectra of the resulting mixtures.

Abstract: A method for determining the amount of photoreactive polynuclear aromatic compound in a sample is described. A sample containing an unknown amount of a photoreactive polynuclear aromatic compound is mixed with a known quantity of a polyhalogenated organic compound and exposed to light of a known wavelength for a known length of time. The quantity of the photoreaction product which results from the light exposure is measured by absorption spectroscopy. Comparison of the absorption measurement to a standard curve allows determination of the concentration of the photoreactive aromatic compound. The simplicity of the method makes it suitable for on-site testing. The method can be used to test for photoreactive compounds in various media, such as soil, aqueous samples, and oil.

Abstract: A device and method for testing for Cystic Fibrosis includes a sample cell having a capillary tube with a lumen that will hold approximately five microliters of sweat. The capillary tube has metallic rings around each end of the tube with an RF oscillator attached to one ring and a microprocessor attached to the other. An RF signal, which is transmitted from the RF oscillator through the sweat in the sample cell, is subsequently analyzed at the microprocessor by comparing the transmitted signal to a reference. In accordance with the comparison made by the microprocessor, the presence of Cystic Fibrosis may be detected.

Abstract: Apparatus for chemical detection includes a cap for coupling with a sample vial containing a sample. The sample includes at least one chemical to be detected. The cap includes a reagent vial which contains a liquid reagent. The reagent vial includes a membrane which substantially retains the liquid reagent and which is substantially permeable to the chemical to be detected. The reagent vial can be opened to allow the chemical to permeate and enter the reagent vial and closed to substantially prevent the chemical from permeating the membrane and entering the reagent vial. In some embodiments, the reagent vial is opened and closed by movement of the reagent vial. In some other embodiments, the reagent vial remains stationary while a device moves to open and close the stationary reagent vial.

Abstract: A colorimetric test strip useful for analysis of free chlorine is provided. In a preferred embodiment, 3,3',5,5'-tetramethylbenzidine is the colorimetric indicator. Beneficially, the carrier for the indicator has been treated to have a pH that eliminates chloramine interference. Advantageously, the indicator in free base form and a suitable water-soluble buffer may be deposited on the carrier using a combined solution of indicator and buffer.

Abstract: An apparatus and method for monitoring the product quality of chlorine in which a sample stream of chlorine is taken from a chlorine stream and a portion of the sample stream is passed to one of three different analyzers for detection of various contaminants. A common data acquisition network receives data from each analyzer for integration and output. The analyzers include a bromine in chlorine analyzer, a non-condensable gas in chlorine analyzer, and a halocarbon in chlorine analyzer.

Abstract: Cystic fibrosis (CF), a lethal genetic disease associated with a defect in Cl transport, is caused by mutations in the gene coding for cystic fibrosis transmembrane conductance regulator (CFTR). Surprisingly, not only wild type CFTR, but several naturally-occurring CFTR mutants carrying a defect in the first nucleotide binding fold (NFB1) all expressed cAMP-activatable Cl currents. Treatment of the CFTR mutants with appropriate concentrations of methylxanthine phosphodiesterase inhibitor (which increases cAMP levels) activated Cl conductance to near wild type levels. The present invention thus provides a new avenue for treating cystic fibrosis by the administration of therapeutically effective amounts of compounds which elevate cAMP levels. Dosage and patient responsiveness to treatment, as well as relative efficacies of the compounds being or to be administered can also be determined in accordance with the methods of present invention.

Abstract: An automated analysis system is provided for the determination of impurities in a liquified hydrocarbon stream. The system employs a hydrocarbon capture vessel for capturing a hydrocarbon sample, a water scrubbing vessel for extracting impurities from the hydrocarbon sample and a titration zone for analyzing the amount of impurities in the aqueous extract.

Abstract: A method for determining trace amounts of total chlorine present in a water sample. The method includes use of DPD as an indicator. The sample is filtered after a color development delay, and then light absorbance through the sample is measured. A control sample is treated with malonic acid to de-chlorinate the control. Light absorbance through the sample being tested is adjusted by the light absorbance through the control sample.

Abstract: A process for the continuous quantitative determination of the concentration of fluorine-containing compounds in gases by treating a gas that contains a fluorine-containing compound with an aqueous solution of an amine and determining the concentration of the eliminated fluoride ions by a direct potentiometric method.

Abstract: A method for monitoring automatically, on-line chloride content in a fluid stream in an oil refinery. Additionally, the present invention provides a method for neutralizing the acids resulting from the chloride in a fluid stream. Pursuant to the method, a fluid sample is collected. To the sample is added a sulfide scavenger that will react with the sulfide that is present to create a reaction product. The fluid is then passed to a reaction or measurement cell including a chloride specific electrode. Prior to contacting the chloride specific electrode, the fluid must pass through a membrane that prevents the reaction product from flowing therethrough. The fluid that flows through the membrane is allowed to contact the chloride specific electrode. This allows the chloride content to be monitored in the fluid. The concentration of chloride can then be used to generate a signal to control the addition of a neutralizing agent to the fluid stream.

Abstract: A method and apparatus for measuring the amount of residual chlorine in solution with enhanced accuracy. The basic measurement technique involves introducing a solution of iodide ion into the sample to reduce the chlorine, thereby producing a proportionate amount of iodine; measurement of the iodine concentration is used to infer the initial amount of chlorine. The accuracy of this measurement technique is enhanced by introducing a sufficient amount of scavenger, preferably finely divided zinc metal, into the iodide solution to react with trace amounts iodine present therein.

Abstract: A method is provided for accurately determining the complexing capacity (or free HF concentration) of a pickling liquor. A sample of pickling liquor is obtained and an excess of ferric ion is added thereto to complex with all of the free HF in the sample. A back titration is performed to determine the residual free ferric ion. The difference between the amount of ferric ion added and that found by the titration is related to the free HF in the original sample.The method is useful in conjunction with an automated, on-line system which periodically monitors a pickling bath and makes any necessary adjustments thereto.

Abstract: The concentration of an organic chlorine compound contained in a gaseous medium is measured in situ by feeding the gaseous medium to a reaction zone and oxidizing the chlorine compound to produce a reactive gas capable of reacting with a chemiluminescent compound to cause chemiluminescence. The reactive gas is contacted with the chemiluminescent compound contained in a cell to cause chemiluminescence whose intensity is proportional to the amount of the reactive gas produced by the oxidation of the organic compound. The concentration of an organic chlorine compound contained in an aqueous medium may also be measured by the similar method after separating the organic chlorine compound as vapors from the aqueous medium. A device suitable for the above measurement is also disclosed.