Abstract: A system for controlling the atmosphere in the container comprising a membrane separation apparatus to separate nitrogen and a second separation apparatus, adapted to separate carbon dioxide and water vapor from a gas mixture in the container. The separated nitrogen is returned to the container, as is at least a portion of the carbon dioxide and water vapor, so as to produce and/or maintain a pre-determined atmosphere composition within the container thereby to prevent spoilage of perishable products within the container.

Abstract: The air is compressed in a precompressor (1) to a prepressure, then cooled, cleaned and reheated. A heat exchanger (2) is used for simultaneous cooling and reheating. The separation of the nitrogen is effected in a separation device (4), which comprises a plurality of membrane separators. The concentrate, which is enriched with nitrogen, from the last stage is recirculated to the inlet side of the precompressor (1). The separated nitrogen is compressed to the nominal pressure in a final compressor (6) connected to the separation device (4). A pressure switch (8) controls the system such that the final compressor (6) only switches on during start-up when the working pressure of the separation device (4) has been reached. Up to this time the gas supplied from the separation device (4) is partially recirculated to the precompressor (1). There is also recirculation of the leakage nitrogen from the final compressor (6) to the precompressor (1).

Abstract: A membrane system controller and control method for maximizing retentate product output and incorporating compressor load detection apparatus and process parameter instrumentation for feeding essential monitoring information to a control unit. Product output maximization is accomplished by increasing the membrane operating temperature during periods when compressor capacity is underutilized.

Abstract: A fuel storage system is provided including at least one storage tank, an air exhaust port, a first filter assembly, a primary pump, a least one secondary pump, at least one additional filter assembly, and an additional secondary pump. The first filter assembly includes a filter input port, a fuel vapor duct, a primary filter output port, and a secondary filter output port. The filter input port is coupled to a fluid vent port. The fuel vapor duct defines a substantially unobstructed flow path extending from the filter input port to a primary filter output port. The primary filter output port is coupled to a pollutant return port. The secondary filter output port is partitioned from the fuel vapor duct by an air-permeable partition. The primary pump is positioned to cause fluid to pass from the filter input port to the primary filter output port.

Abstract: The present invention relates to devices for conducting, simultaneously, exothermic and endothermic chemical conversions with transfer of heat therebetween. More particularly, this invention relates to autothermic modules using oxygen ion-conducting dense ceramic membranes to separate, selectively, oxygen from an oxygen-containing gas and supply it directly to partial combustion of gaseous organic compounds. Processes using autothermic modules in accordance with this invention are, advantageously, used for production of synthesis gas comprising carbon monoxide and molecular hydrogen which synthesis gas is substantially free of deleterious and/or inert gaseous diluents such as nitrogen. In particular, for conversions, within the integral autothermic module, of natural gas or other forms of gaseous lower alkanes to synthesis gas by means of partial combustion followed by reforming.

Abstract: A process for producing at least an oxygen product gas stream, and power from a gas turbine, by compressing a feed gas stream containing elemental oxygen and heating the feed gas stream on the retentate side of an ion transport reactor membrane section to produce a heated feed gas stream. Oxygen permeating the ion transport reactor membrane section is reacted with a first fuel gas stream to produce a first combustion products gas stream. The heated feed gas stream is separated using an ion transport separator membrane section having a retentate side and a permeate side into an oxygen-depleted gas stream on the retentate side and an oxygen-containing gas stream on the permeate side. At least a portion of the first combustion products gas stream can be recovered, and energy is extracted from at least one gas stream to be expanded in a gas turbine to produce energy.

Abstract: A macroporous polymeric adsorbent is used to remove oil mist and oil vapors from compressed air produced by an oil-lubricated air compressor prior to feeding the compressed air to an air separation membrane system. The macroporous polymeric adsorbent, previously known only for its ability to extract low molecular weight volatile organic compounds from liquids and gases, retains its ability to extract the oil for extended periods of time and outperforms the commonly used activated carbon of the prior art.

Abstract: A diffusional gas transfer system and method having a membrane disposed between a first gas domain and a second gas domain. The first gas domain includes a first mechanism for directing a first environmental gas flow transversely over and in contact with a first surface of the membrane. The second gas domain includes a second mechanism for directing a second environmental gas flow transversely over and in contact with a second surface of the membrane. The membrane is a diffusional gas transfer medium having a multiplicity of tortuous pathways extending from the first surface of the membrane to the second surface of the membrane. The void volume fraction of the membrane is at least 0.2. The membrane is capable of substantially blocking the transfer of particles from the first gas domain to the second gas domain, while permitting the diffusion of gases between the first and second gas domains.

Abstract: Carbogenic molecular sieve devices comprising a porous support (e.g., a metal support) having a carbogenic molecular sieve membrane attached to one or more surfaces of the support so that small pores in the membrane are in communication with larger pores in the support and methods of making the devices.

Abstract: Separation membranes excellent in strength, durability, heat resistance and solvent resistance as well as in balance between substance separation properties and substance permeability are disclosed, which are formed from polyhydrazidoimide resins, and preferably comprises a non-porous dense layer formed from a polyhydrazidoimide resin obtained from the reaction of an aromatic tetracarboxylic dianhydride such as 4,4'-(hexafluoroisopropylidene)diphthalic anhydride and an aromatic dihydrazide such as isophthalic dihydrazide as essential components.

Abstract: A process for producing a gas stream containing oxygen and steam to feed a coal gasifier or other downstream process by compressing and heating a feed gas stream, and separating the heated feed gas stream into an oxygen-depleted gas stream on a retentate side of an ion transport membrane and an oxygen-containing gas stream on a permeate side. The permeate side is purged with a purge gas stream containing steam to produce a gas stream containing oxygen and steam, and at least a portion of the gas stream containing oxygen and steam is fed to the coal gasifier after blending with a pure oxygen stream recovered from the remaining portion of the purge stream or by a parallel nonpurged ion transport separator in the system to achieve the appropriate steam-to-oxygen ratio for the downstream process.

Abstract: An uncontrollable dehydrator where the uncontrollable discharge is augmented with a purge gas to increase the capacity of the dehydrator to achieve a target flow rate and dew point.

Abstract: A process for producing an oxygen-depleted gas stream and a high-pressure gas stream containing oxygen and steam by compressing a feed gas stream containing elemental oxygen, heating the feed gas stream, and separating the heated feed gas stream using one or more ion transport modules into the oxygen-depleted gas stream on a retentate side and an oxygen gas stream on a permeate side of an ion transport membrane. The permeate side is purged using a high-pressure purge gas stream containing steam to produce the high-pressure gas stream containing oxygen and steam, which is directed to a turbine to recover power and produce an expanded, lower-pressure gas stream containing oxygen and steam.

Abstract: A process for separating a feed gas stream containing elemental oxygen and nitrogen to produce a purified nitrogen gas stream by removing oxygen from the feed gas stream using an ion transport membrane to produce a retentate gas stream and a permeate gas stream, wherein the feed gas stream or the retentate gas stream is purified to remove impurities either before or after the separation step to produce the purified nitrogen gas stream.

Abstract: This invention comprises a method and apparatus for obtaining from air an oxygen enriched gas mixture containing at least 40 mole % nitrogen. The apparatus comprises a gas turbine, an oxygen separation unit which is in fluid communication with the turbine air compressor and means for maintaining a proper mass balance tolerance between the turbine compressor/unit and the turbine energy production unit.This invention comprises a method and apparatus for recovering large quantities of an oxygen enriched gas from the volume of a compressed air stream produced by a gas turbine by compensation of the mass loss to the energy production unit section thereof by providing means for maintaining the turbine in proper mass and thermal balance as the turbine is utilized to provide the duty/power requirements of a process which utilizes the oxygen enriched gas stream as a reactant.

Abstract: A solid electrolyte ion transport membrane composite for separating a gaseous species from a gaseous mixture in which the composite has a dense matrix material and a porous coating. The dense membrane is comprised of a matrix material which conducts at least one type of ion, and at least one membrane constituent. The porous coating is disposed on the membrane to enhance the rate of surface reactions involving the gaseous species.

Abstract: A process for producing a pressurized oxygen stream by compressing and heating a feed gas stream containing elemental oxygen, and separating the heated feed gas stream using an ion transport module into an oxygen-depleted gas stream on the retentate side and an oxygen-containing gas stream on a permeate side. The permeate side of the ion transport membrane is purged using a gas stream containing steam to produce a pressurized gas stream containing oxygen and steam, and the gas stream is separated into the pressurized oxygen stream saturated with water vapor and a residual water stream.

Abstract: This invention provides a polyamide separation membrane, prepared from high molecular weight polyamide having a repeating unit represented by the formula (I) and a process for separating gaseous mixtures using them. ##STR1## wherein, R is an aliphatic or aromatic organic group derived from dicarboxylic acid or halide. The polyamide separation membrane according to the present invention has a large free volume and good permeation properties such as permeability and permeation selectivity.

Abstract: Processes and systems to recover at least one perfluorocompound gas from a gas mixture are provided. In one embodiment the inventive process comprises the steps of a) providing a gas mixture comprising at least one perfluorocompound gas and at least one carrier gas, the gas mixture being at a predetermined pressure; b) providing at least one glassy polymer membrane having a feed side and a permeate side; c) contacting the feed side of the at least one membrane with the gas mixture; d) withdrawing from the feed side of the membrane as a non-permeate stream at a pressure which is substantially equal to the predetermined pressure a concentrated gas mixture comprising essentially the at least one perfluorocompound gas; and e) withdrawing from the permeate side of the membrane as a permeate stream a depleted gas mixture comprising essentially the at least one carrier gas.

Abstract: An article for the separation, storage and delivery of substantially pure oxygen, comprises a closed walled, hollow container wherein at least a portion of at least one wall of the container is an oxygen separation material, providing a sole means for transporting substantially all oxygen into the container. An apparatus for the delivery of oxygen comprises means for transferring oxygen from a fluid containing oxygen to at least one such container at elevated temperature and pressure. The apparatus can provide means for transporting said the substantially pure oxygen-bearing container, means for storing said the container, and means for extracting oxygen from the container. A process includes filling the article with substantially pure oxygen, and, storing the substantially pure oxygen within the container for a selected period of time. The process may include releasing the oxygen from the container.

Abstract: An oxygen generating device (11, 211) to which a gas mixture containing oxygen is fed, and which is operable to separate the gas mixture into oxygen rich and oxygen depleted gas components, the device (11, 211) including a negative temperature coefficient material (36a 36b 36c; 236) which is active at an elevated temperature above a minimum operating temperature, to separate the gas mixture into oxygen rich and oxygen depleted gas components, there being an electronic control unit coupled to the device to pass an electrical current through the device (11, 211) to produce a heating effect within the device to heat the gas mixture at least towards the minimum operating temperature wherein the device includes a plurality of active sections (A, B, C) through each of which the gas mixture passes in turn, and the electrical current supply is connected to each of the sections (A, B, C) so that the sections electrically are connected in series.

Abstract: A process for separating a feed gas stream into an oxygen-enriched gas stream which is used in a combustor and an oxygen-depleted gas stream. The feed gas stream is compressed, and oxygen is separated from the compressed feed gas stream using an ion transport module including an ion transport membrane having a retentate side and a permeate side. The permeate side of the ion transport membrane is purged with at least a portion of a combustion product gas stream obtained from the combustion in the combustor of the gas stream exiting the permeate side of the ion transport module.

Abstract: A membrane process and apparatus are described for the production of a desired very high purity permeate gas by use of a multiple stage membrane process wherein in a primary stage a process feed gas mixture is provided to a primary membrane separator unit comprising a membrane having a relatively high intrinsic permeability to provide an intermediate permeate gas and a retentate gas, and providing the intermediate permeate gas in a secondary stage to a secondary membrane separator unit comprising a membrane having a relatively low intrinsic permeability, to produce therefrom a very high purity permeate gas product.

Abstract: A system that includes an equipment package for separating nitrogen from air to produce enhanced oxygen air for use by divers. The package is combined with a pressure storage tank for air that is coupled to the package. A pressure storage tank is provided for enhanced oxygen air. A fill station including a high pressure gauge and a high pressure oxygen sensor is provided to fill divers' tanks. A compressor receives the enhanced oxygen air from the package and delivers high or low pressure enhanced oxygen air to the pressure storage tank via a pressure filter. Valving is provided for selectively controlling the flow in the system.

Abstract: A process for producing an oxidized product in conjunction with a turbine for generating power. This process comprises contacting a compressed and heated oxygen-containing gas stream with at least one solid electrolyte oxygen selective ion transport membrane in a membrane reactor. A reactant is passed into the reactor to generate an oxidized product therefrom. Oxygen-depleted retentate stream from the reactor is added to a gas turbine combustor and expanded in a gas turbine to generate power.

Abstract: A system for generating oxygen enriched air includes a compressed air supply for supplying compressed air and a permeable membrane gas separation system for separating a nitrogen gas component and an oxygen enriched air component from the compressed air. An oxygen analyzer is provided to detect an oxygen concentration in the oxygen enriched air component. The nitrogen gas component is divided, by a vortex tube, into a cold gas stream and a hot gas stream, and solenoid valves are actuated to modify a flow path of the compressed air through the cold gas stream and the hot gas stream in order to selectively heat and cool the compressed air. The oxygen enriched air is then selectively distributed for further use.

Abstract: A method and device indirectly monitors the purity of nitrogen gas manufactured from air using a permeable membrane to separate air components. A gas flow measuring device inserted in gas conduits downstream from the membrane monitors nitrogen gas purity by measuring normal flow and detects deviation from desired purity levels by changing gas flow caused by manufacturing apparatus malfunctions.

Abstract: A process for oxygen-enriching a first feed gas stream be fed into a furnace by utilizing an oxygen-enriched gas stream from a second feed gas stream, wherein the first feed gas stream is compressed and then heated prior to injection into the furnace. The second feed gas stream is separated using an ion transport module containing an ion transport membrane having a retentate side and a permeate side to produce an oxygen-depleted gas stream on the retentate side and the pure oxygen gas stream or the oxygen-enriched gas stream on the permeate side. The pure oxygen gas stream or the oxygen-enriched gas stream is added to the first feed gas stream at any location before the first feed gas stream enters the furnace.

Abstract: A process for recovering SF.sub.6 from a gas is provided. The process includes the step of contacting a gas stream comprising SF.sub.6 and at least one of N.sub.2, O.sub.2, CO.sub.2, and H.sub.2 O with a membrane in at least one membrane separation unit at conditions effective to obtain a retentate stream rich in SF.sub.6 and a permeate stream rich in at least one of N.sub.2, O.sub.2, CO.sub.2, and H.sub.2 O.

Abstract: A process for removing oxygen from a feed gas stream to produce an oxygen-depleted retentate gas stream by supplying the feed gas stream to a bulk oxygen separation system for removing oxygen to produce an oxygen-depleted crude product gas stream and a first oxygen-containing permeate effluent stream, and supplying the oxygen-depleted crude product gas stream to a separator having a primary ion transport membrane to produce a second permeate effluent stream and the oxygen-depleted retentate gas stream. A reactive purge gas is added to react with a portion of the oxygen permeating through the primary ion transport membrane and purge the permeate side of the primary ion transport membrane, and/or a recycle gas stream comprising at least a portion of one gas stream produced during the process is added to at least one other of the gas streams.

Abstract: The present invention discloses a mixed ionic electronic conductor membrane comprising a dense layer sandwiched between two porous layers. Furthermore the invention discloses the application of this membrane to the use of partial oxidation of hydrocarbons. One porous layer, which is in contact with air, promotes the generation of oxygen ions. The oxygen ions diffuse through the dense layer to the second porous layer which is in contact with a hydrocarbon and result in partial oxidation of the hydrocarbon.

Abstract: A system for generating oxygen enriched air includes a compressed air supply for supplying compressed air and a permeable membrane gas separation system for separating a nitrogen gas component and an oxygen enriched air component from the compressed air. An oxygen analyzer is provided to detect an oxygen concentration in the oxygen enriched air component. The nitrogen gas component is divided, by a vortex tube, into a cold gas stream and a hot gas stream, and solenoid valves are actuated to modify a flow path of the compressed air through the cold gas stream and the hot gas stream in order to selectively heat and cool the compressed air. The oxygen enriched air is then selectively distributed for further use.

Abstract: The present invention provides a process for recovering sulfur hexafluoride ("SF.sub.6 ") from a gas stream using membrane separation.

Abstract: A process for operating a permeable membrane generator at above or below design conditions therefor, which entails adjusting the permeation temperature of a feed stream permeating said membrane generator by heating or cooling means, thereby providing a desired amount, purity and pressure of a product gas.

Abstract: A process for inhibiting the formation of carbon and/or coke from a carbon-containing reactive gas stream on the permeate side of an oxygen ion transport membrane, or for increasing the oxygen partial pressure thereon, by separating a feed gas stream to form an oxygen-depleted gas stream on the retentate side and a gas stream containing oxygen reaction products on the permeate side. The permeate side is purged with the carbon-containing reactive gas stream, and at least a portion of the exhaust gas stream formed from the reaction of the reactive gas stream with the separated oxygen is recirculated to purge the permeate side.

Abstract: This invention relates to a method of an apparatus and method for separating component gases in a gas mixture employing a glassy polymer membrane at temperatures at or slightly above the freezing point of any liquid present so as to achieve superior separator of gas components. The composition of certain monomers and polymers are claimed.

Abstract: A system and process for producing a high-purity product from a feed stream containing elemental oxygen by applying the feed stream to at least one separator including a feed zone and a permeate zone separated by a solid electrolyte membrane, and driving a portion of oxygen contained in the feed stream from the feed zone to the permeate zone via the membrane by applying to the permeate zone a reactive purge stream containing a reactive gas which combines with oxygen to establish a lower partial pressure of oxygen in that zone. Oxygen-depleted retentate is withdrawn as a high-purity product stream.

Abstract: A process and installation for the separation of air by permeation, for the production of high purity nitrogen. The installation comprises in series an air compressor (2), a refrigerator (3) cooled by air or water, a unit (4) for filtering out oil and water, an air reheater (5) and a permeator (6). The air reheater (5) is provided with a device (18A) for adjusting the temperature as a function of the temperature of the final refrigeration fluid that cools the compressed air.

Abstract: An air separation system and method for producing a plurality of oxygen product streams at varying pressures and purities. The system combines a VPSA oxygen generator with a multi-stage cascade membrane unit to provide a high pressure, low purity product stream and a low pressure, high purity product stream.

Abstract: A process for producing and oxygen gas stream, an oxygen-enriched gas stream, or a reaction product stream as a permeate stream and an oxygen-depleted retentate gas stream by first separating oxygen from a feed gas stream and thereafter cooling at least the permeate stream. The production and cooling of the permeate stream occurs within a single apparatus having at least one ion transport membrane.

Abstract: An ion transport reactor and process for using same having at least one ion transport membrane with a retentate side and a permeate side, for extracting oxygen from a feed gas stream as it flows along the retentate side. A reactant gas stream is flowed along the permeate side of the ion transport tubes to react with the oxygen transported therethrough. Heat is transferred to a fluid stream flowing through the ion transport reactor while the temperature of the membrane is maintained within its operating range.

Abstract: The present invention provides a process for preparing membranes using novel silicon containing polyarylates of Formula I ##STR1## where R.sub.1 to R.sub.8 represent hydrogen, alkyl groups containing 1 to 5 methylene group or halogen atoms, R.sub.9 and R.sub.10 represents alkyl groups containing 1 to 5 carbon atoms or CF.sub.3 group and R.sub.11 and R.sub.12 represent alkyl groups with 1 to 5 carbon atoms or phenyl groups.

Abstract: The present invention presents a new class of multicomponent metallic oxides which are particularly suited toward use in fabricating component used in solid-state oxygen separation devices. The compositions of the present invention are represented by the formula Ln.sub.x A'.sub.x ' Co.sub.y Fe.sub.y' Cu.sub.y" O.sub.3-z wherein Ln is an element selected from the f block lanthanides as represented by the IUPAC periodic table of the elements, A' is selected from strontium or calcium, x>0, y>0, y'>0, x +x'=1, y +y'+y"=1, 0.ltoreq.y"<0.4 and z is a number which renders the composition of matter charge neutral. These compositions provide a favorable balance of oxygen permeance, resistance of degradation when employed in such devices under high oxygen partial pressures and possess coefficients of thermal expansion which are compatible with other materials used to fabricate such devices.

Abstract: A process for recovering at least one of CF.sub.4 and C.sub.2 F.sub.6 from a vent gas from an aluminum electrolysis cell. The process includes the steps of:(a) removing inorganic fluorides from a vent gas comprising inorganic fluorides and at least one of CF.sub.4 and C.sub.2 F.sub.6 to obtain a purified vent gas; and(b) contacting the purified vent gas with a membrane at conditions effective to obtain a retentate stream rich in at least one of CF.sub.4 and C.sub.2 F.sub.6, and a permeate stream depleted in at least one of CF.sub.4 and C.sub.2 F.sub.6.

Abstract: The present invention relates to novel solid state mixed conductor membranes and their use for separating oxygen from oxygen-containing feeds at elevated temperatures. The membranes comprise a multicomponent metallic oxide of substantially cubic perovskite structure, stable in air over the temperature range of 25.degree.-950.degree. C., having no connected through porosity wherein the membrane is of a composition represented by the formula ?A.sub.1-x A'.sub.x !?Co.sub.1-y-z B.sub.y B'.sub.z !O.sub.3-.delta., where A.tbd.Ca, Sr, Ba, and mixtures thereof; A'.tbd.La, Y, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th, U, and mixtures thereof; B.tbd.Fe, Mn, Cr, V, Ti, and mixtures thereof; B'.tbd.Cu, Ni, and mixtures thereof; .about.0.0001.ltoreq.x.ltoreq..about.0.1; .about.0.002.ltoreq.y<0.05; .about.0.0005.ltoreq.z.ltoreq..about.0.3; .delta. is determined by the valence of the metals.

Abstract: Processes and systems to recover at least one perfluorocompound gas from a gas mixture are provided. In one embodiment the inventive process comprises the steps of a) providing a gas mixture comprising at least one perfluorocompound gas and at least one carrier gas, the gas mixture being at a predetermined pressure; b) providing at least one glassy polymer membrane having a feed side and a permeate side; c) contacting the feed side of the at least one membrane with the gas mixture; d) withdrawing from the feed side of the membrane as a non-permeate stream at a pressure which is substantially equal to the predetermined pressure a concentrated gas mixture comprising essentially the at least one perfluorocompound gas; and e) withdrawing from the permeate side of the membrane as a permeate stream a depleted gas mixture comprising essentially the at least one carrier gas.

Abstract: A process for separating two low-boiling components of a gas-phase mixture. The invention involves three separation steps: condensation, flash evaporation and membrane separation. The steps are integrated together in such a way as to provide a good separation between the components, and to avoid creation of secondary streams that need additional treatment. The invention is particularly useful for separation of low molecular weight organic compounds from other gases.

Abstract: Oxygen is recovered from a hot, compressed oxygen-containing gas, preferably air, by an oxygen-selective ion transport membrane system. Hot, pressurized non-permeate gas from the membrane is cooled and useful work is recovered therefrom by expansion at temperatures below the operating temperature of the membrane. The recovered work is used together with the oxygen permeate product in applications such as oxygen-enriched combustion of liquid fuels, wood pulping processes, steel production from scrap in mini-mills, and metal fabrication operations. Oxygen permeate product can be compressed utilizing a gas booster compressor driven by expansion of cooled, pressurized non-permeate gas.

Abstract: An apparatus and method for controlling the output of an oxygen concentrator wherein an oxygen concentrator indicator is comprised of an oxygen sensor monitor and circuit board which receives a gas sample from the concentrator, the oxygen concentrator indicator circuit board converts the concentration of oxygen to a DC voltage range from 0 to 1 volt corresponding to 0% to 100% oxygen. A plurality of set-point amplifiers accept the voltage and feed the voltage to a logic block where the voltage is analyzed to insure that only one of a plurality of solid state relays or switches is energized at a time. A plurality of taps on an AC motor winding are selectively energized by the solid state relays to drive the oxygen concentrator at a pre-determined rate in response to the concentration of oxygen generated by the concentrator.

Abstract: A process for removing oxygen from a feed stream to obtain an oxygen-depleted product stream by applying the feed stream to at least one separator including a feed zone and a permeate zone separated by a solid electrolyte mixed conductor membrane, and driving a first portion of entrained oxygen in the feed stream from the feed zone to the permeate zone via the mixed conductor membrane by applying at least one of a purge stream and a negative pressure to the permeate zone to establish a lower partial pressure of oxygen in that zone. Oxygen-depleted retentate is withdrawn as a product stream. Preferably, at least one additional solid electrolyte ionic or mixed conductor membrane is also employed in feed series with the mixed conductor membrane.