Abstract: In order to make a power generation quantity of a cell for fuel cell increase in a short time when a drop in moistness of the cell causes the power generation quantity of the cell to decrease, a cathode of the cell includes a conductive material, catalyst, and ionomer which covers the conductive material and catalyst. If an output voltage value of the cell is lower than a predetermined threshold voltage value and an electrical resistance value of the cell is higher than a predetermined threshold resistance value, control for increasing an oxidizing gas amount which increases an amount of oxidizing gas sent to the cell is performed.

Abstract: A titanium-oxide catalyst containing catalytic metal shows catalysis under high temperature conditions. A titanium-oxide catalyst contains a titanium-oxide nanoparticle assembly and ruthenium particles. The titanium-oxide nanoparticle assembly is an assembly of titanium-oxide nanoparticles, which are nanoparticles of titanium oxide. The ruthenium particles have a smaller particle diameter than the titanium-oxide nanoparticle assembly and the titanium-oxide nanoparticles. The ruthenium particles are dispersed and supported on a surface of the titanium-oxide nanoparticle assembly.

Abstract: A titanium-oxide catalyst containing catalytic metal shows catalysis under high temperature conditions. A titanium-oxide catalyst contains a titanium-oxide nanoparticle assembly and ruthenium particles. The titanium-oxide nanoparticle assembly is an assembly of titanium-oxide nanoparticles, which are nanoparticles of titanium oxide. The ruthenium particles have a smaller particle diameter than the titanium-oxide nanoparticle assembly and the titanium-oxide nanoparticles. The ruthenium particles are dispersed and supported on a surface of the titanium-oxide nanoparticle assembly.

Abstract: In some examples, a fuel cell comprising a cathode, a cathode conductor layer adjacent the cathode, an electrolyte separated from the cathode conductor layer by the cathode, and an anode separated from the cathode by the electrolyte, wherein the anode, cathode conductor layer, cathode, and electrolyte are configured to form an electrochemical cell, and wherein at least one of cathode or the cathode conductor layer includes an exsolute oxide configured to capture Cr vapor species present in the fuel cell system.

Abstract: A fuel cell comprises a plurality of sub-cells, each sub-cell including a first electrode in fluid communication with a source of oxygen gas, a second electrode in fluid communication with a source of a fuel gas, and a solid electrolyte between the first electrode and the second electrode. The sub-cells are connected with each other with an interconnect. The interconnect includes a first layer in contact with the first electrode of each cell, and a second layer in contact with the second electrode of each cell. The first layer includes a (La,Mn)Sr-titanate based perovskite represented by the empirical formula of LaySr(1-y)Ti(1-x)MnxOb. In one embodiment, the second layer includes a (Nb,Y)Sr-titanate perovskite represented by the empirical formula of Sr(1-1.5z-0.5k±?)YzNbkTi(1-k)Od.

Abstract: A membrane electrode assembly is provided which includes an anode; a cathode; a membrane between the anode and the cathode; and a protective layer between the membrane and at least one electrode of the anode and the cathode, the protective layer having a layer of ionomer material containing a catalyst, the layer having a porosity of between 0 and 10%, an ionomer content of between 50 and 80% vol., a catalyst content of between 10 and 50% vol., and an electrical connectivity between catalyst particles of between 35 and 75%. A configuration using a precipitation layer to prevent migration of catalyst ions is also provided.

Abstract: A method for uniformly forming a nickel-metal alloy catalyst in a fuel electrode of a solid oxide electrolysis cell is provided. Specifically, before the nickel-metal alloy catalyst is formed, a metal oxide is uniformly distributed on nickel oxide contained in the fuel electrode through infiltration of a metal oxide precursor solution and hydrolysis of urea.

Abstract: An illustrative example fuel cell electrolyte management device includes a first component having a first density and a second component having a second density that is less than the first density. The first component has a first side including a pocket and a second side facing opposite the first side. The second side of the first component includes a first plurality of fluid flow channels. The second component has a porosity configured for storing electrolyte in the second component. The second component fits within the pocket. The second component has a first side received directly against the first side of the first component. The second component has a second side including a second plurality of fluid flow channels.

Abstract: The present disclosure is directed to a method and system for dynamically controlling seal decompression. The method includes monitoring a set of parameters associated with an operation of a seal, wherein the set of parameters includes a maximum pressure subjected to the seal and an exposure time at the maximum pressure, calculating a target pressure ramp down rate based on at least one of the maximum pressure and the exposure time, and decreasing a pressure about the seal at a decompression rate that is based on the target pressure ramp down rate.

Abstract: After formation of a silicon nitride gate spacer and a silicon nitride liner overlying a disposable gate structure, a dielectric material layer is deposited, which includes a dielectric material that is not prone to material loss during subsequent exposure to wet or dry etch chemicals employed to remove disposable gate materials in the disposable gate structure. The dielectric material can be a spin-on dielectric material or can be a dielectric metal oxide material. The dielectric material layer and the silicon nitride liner are planarized to provide a planarized dielectric surface in which the disposable gate materials are physically exposed. Surfaces of the planarized dielectric layer is not recessed relative to surfaces of the silicon nitride layer during removal of the disposable gate materials and prior to formation of replacement gate structures, thereby preventing formation of metallic stringers.

Abstract: A solid oxide fuel cell includes a fuel cell main body which includes a cathode layer, a solid electrolyte layer, and an anode layer and which has a power generation function; a connector disposed to face one electrode layer of the cathode layer and the anode layer; a current collector which is disposed between the one electrode layer and the connector and which is in contact with a surface of the one electrode layer and a surface of the connector, the surfaces facing each other, to thereby electrically connect the one electrode layer and the connector; and a groove provided in a portion of a surface of the one electrode layer, which surface is located on the side where the one electrode layer is in contact with the current collector, the portion of the surface being not in contact with the current collector.

Abstract: Various embodiments include methods of fabricating an interconnect for a fuel cell stack. Methods for controlled pre-oxidation of an interconnect include oxidizing in a nitride-inhibiting environment to inhibit the formation of nitrides.

Abstract: An example fuel cell stack component includes a metallic layer applied to the component and an oxide layer applied to the metallic layer. The oxide layer includes a chemical component that is not in the metallic layer.

Abstract: The present invention concerns a breathable product for protective mass transportation and cold chain applications, in particular a reflective sheet for covering temperature sensitive products the reflective sheet having at least a first layer made of a highly reflective moisture vapor permeable substrate having an outer side and an inner side, wherein said inner side comprises in addition at least a metal layer deposited by a PVD process to provide a thermal insulation through high reflection low convection while providing controlled moisture vapor permeability.

Abstract: An illustrative example method of making a fuel cell component includes mixing a catalyst material with a hydrophobic binder in a solvent to establish a liquid mixture having at least some coagulation of the catalyst material and the hydrophobic binder. The liquid mixture is applied to at least one side of a porous gas diffusion layer. At least some of the solvent of the applied liquid mixture is removed from the porous gas diffusion layer. The catalyst material remaining on the porous gas diffusion layer is dried under pressure.

Abstract: A positive electrode for lithium ion secondary batteries includes a collector and a positive electrode active material layer formed on at least one surface of the collector. The positive electrode active material layer contains a lithium-containing metal oxide having a unit cell represented by the following formula and a conductive material and has voids with a volume of 0.82×10?3 cm3/cm2 to 7.87×10?3 cm3/cm2 per unit area of the collector: LiFe1-xZrxP1-ySiyO4??(1) where 0<x<1 and 0<y<1. The unit cell has lattice constants satisfying 10.326?a?10.335, 6.006?b?6.012, and 4.685?c?4.714. The sum of the volume of the lithium-containing metal oxide and the volume of the conductive material is 1.61×10?3 cm3/cm2 to 6.46×10?3 cm3/cm2 per unit area of the collector.

Abstract: The invention provides a nonaqueous electrolyte secondary battery having a cathode and an anode arranged so as to be opposite to each other, and an electrolyte layer put therebetween; wherein the cathode comprises: (a) a conductive polymer and (b) at least one selected from the group consisting of a polycarboxylic acid and a metal salt thereof, and wherein the anode comprises a material into which a base metal or ions thereof can be inserted and from which a base metal or ions thereof can be extracted. The invention further provides a cathode sheet for use in the nonaqueous electrolyte secondary battery mentioned above.

Abstract: The present invention provides: an electrode-supporting type of gas-separation membrane module for selectively effecting the passage of a gas via an electron exchange reaction due to a coupling-material layer and gas exchange via an ion-conducting separation layer; a tubular structure of same; a production method for the tubular structure; and a hydrocarbon-reforming method using the gas-separation membrane module. The present invention is advantageous in that outstanding chemical and mechanical durability can be ensured by using a fluorite-based ion-conducting membrane which is chemically stable in CO2 and H2O atmospheres in particular, at high temperature, and in that a pure gas can be produced inexpensively since the passage of gas occurs due to an internal circuit even without applying a voltage from the outside.

Abstract: A fuel cell membrane electrode assembly is provided comprising a polymer electrolyte membrane comprising a first polymer electrolyte and at least one manganese compound; and one or more electrode layers comprising a catalyst and at least one cerium compound. The membrane electrode assembly demonstrates an unexpected combination of durability and performance.

Abstract: There is provided a technique that suppresses a variation in particle diameter of a metal catalyst in the process of supporting the metal catalyst on a carrier. A CNT substrate having carbon nanotubes (CNTs) as the carrier arrayed thereon is placed in a processing chamber. Carbon dioxide is supplied to the processing chamber. After the carbon dioxide in the processing chamber is made supercritical, a complex solution in which a platinum complex is dissolved is supplied to the processing chamber. A sample temperature denoting temperature of the CNTs is controlled to be higher than an ambient temperature in the processing chamber. The CNT substrate is heated, such that a temperature difference between the ambient temperature and the sample temperature repeats increasing and decreasing. After the state of the supercritical fluid is changed to a non-supercritical state, the CNT substrate is heated, so as to cause the metal catalyst to deposit on the surface of the CNTs.

Abstract: Methods of growing boron nitride nanotubes and silicon nanowires on carbon substrates formed from carbon fibers. The methods include applying a catalyst solution to the carbon substrate and heating the catalyst coated carbon substrate in a furnace in the presence of chemical vapor deposition reactive species to form the boron nitride nanotubes and silicon nanowires. A mixture of a first vapor deposition precursor formed from boric acid and urea and a second vapor deposition precursor formed from iron nitrate, magnesium nitrate, and D-sorbitol are provided to the furnace to form boron nitride nanotubes. A silicon source including SiH4 is provided to the furnace at atmospheric pressure to form silicon nanowires.

Abstract: A method for forming a hydrolytically-stable hydrophilic coating on a fuel cell flow field plate comprises contacting a flow field plate with a titanium oxide sol to form a titanium oxide layer disposed upon the flow field plate. The coated flow field plate is subsequently contacted with a silicon oxide sol to form a silicon oxide/titanium oxide bilayer disposed upon the flow field plate. A flow field plate formed by the method is also provided.

Abstract: An aspect of the subject technology/invention of the present disclosure includes electrode structures or elements/components that have (e.g., present) fractal and/or self-complementary shapes or structures, e.g., on a surface. Such shapes or structures can be pre-existing. The electrodes can be made of any suitable material. The electrodes may function or operate or be used as a “seed” structure to incorporate or receive a material or materials useful for lattice assisted nuclear reactions and/or cold fusion processes.

Abstract: A power generator includes a cavity to accept a hydrogen producing fuel cartridge. A channel is coupled to receive hydrogen from the fuel cartridge. A manifold is coupled to the channel to receive hydrogen from the channel, the manifold having an opening to receive oxygen and water vapor, the manifold being positioned to provide the water vapor to the cavity. An array of fuel cell membranes is supported by the manifold to receive hydrogen from the manifold and oxygen from the opening in the manifold.

Abstract: There is disclosed a method and components for repairing a fuel cell stack. In particular, the method and components relate to repairing a high temperature fuel cell stack incorporating ceramic components. The method includes identifying a fuel cell bundle within a fuel cell strip to be disconnected from the fuel cell strip, identifying at least one fuel feed pipe portion connected to the fuel cell bundle, and identifying at least one fuel outlet pipe portion connected to the fuel cell bundle. A cutting blade is positioned on the fuel feed pipe portion and cutting through the fuel feed pipe portion, and similarly for the fuel outlet pipe portion. The fuel cell bundle is then removed, and a replacement inserted in its place.

Abstract: The invention relates to an apparatus for the coating of a substrate, in particular of a circuit board, with a material application device for applying a coating material and with a gas supplying device for the supply of a gaseous medium, the material application device having an inner tubular element, the gas supply device having an outer tubular element which is arranged coaxially to the inner tubular element and surrounds the latter, so as to form between the outer and the inner tubular element a gas supply duct which has an annular orifice at one end, the supply duct being configured so that the gaseous medium flows out, parallel to the coating material, through the annular orifice, in order, when it impinges on the substrate, to displace the applied coating material and thereby distribute it over the area. The apparatus is distinguished in that the material application device has a jet valve which, in a first operating mode, carries out a jetted supply of material into the inner tubular element.

Abstract: The present invention provides a manufacturing method of an electrode catalyst layer which contains a catalyst, carbon particles and a polymer electrolyte, wherein an oxide type of non-platinum catalyst is used as the catalyst and a fuel cell employing the electrode catalyst layer achieves a high level of power generation performance. The manufacturing method of the electrode catalyst layer of the present invention includes at least: preparing a first catalyst ink, in which a catalyst, first carbon particles and a first polymer electrolyte are dispersed in a first solvent, drying the first catalyst ink to form complex particles, preparing a second catalyst ink, in which the complex particles, second carbon particles and a second polymer electrolyte are dispersed in a second solvent, and coating the second catalyst ink on a substrate to form the electrode catalyst layer.

Abstract: The present invention is concerned with methods for the deposition of ceramic films on ceramic or metallic surfaces, particularly the deposition of sub-micron thickness ceramic films such as films of stabilised zirconia and doped ceria such as CGO (cerium gadolinium oxide). The present invention is particularly useful in the manufacture of high and intermediate temperature operating fuel cells including solid oxide fuel cells (SOFC) and also metal supported intermediate temperature SOFC operating in the 450-650° C. range.

Abstract: The present invention relates to a lithium-air battery including: a negative electrode containing a negative-electrode active material; a positive electrode using oxygen as a positive-electrode active material; and an electrolyte medium arranged between the negative electrode and the positive electrode; wherein the electrolyte medium includes as primary solvent one or more compounds having an —N—CO— group in the molecule.

Abstract: A method of preparation of metal-chalcogen-nitrogen-carbon (M-Ch-N—C) catalytic material utilizing a sacrificial support approach and using inexpensive and readily available precursors is described. Furthermore, the catalytic materials synthesized using the disclosed methods include multiple types of active sites.

Abstract: A fuel cell separator is provided with an opening that functions as a manifold. A resin coating is formed within the peripheral area of the fuel cell separator, in a state where the power generation area is masked with a masking jig. Subsequently, the masking jig is removed, and a conductive coating is formed within the power generation area of the fuel cell separator, the peripheral area of which has been masked by the resin coating.

Abstract: The present disclosure provides a method of generating electricity from a long chain hydrocarbon, said method comprising contacting the liquid non-polar substrate with a plurality of enzymes, wherein at least one enzyme is non-electric current/potential enzyme that functions as a catalyst for chemical reaction transforming a first substrate or byproduct to a second substance that can be used with an additional electric current/potential generating enzyme.

Abstract: A process for manufacturing an electrochemically active device comprising the steps of: —providing a substrate (110) comprising an electrode receiving surface portion (111) having substantially constant wetting tension throughout said electrode receiving surface portion, —providing a plurality of first electrodes (120) directly on said electrode receiving surface portion, —leaving intermediate portions (130) of said electrode receiving surface portion (111) free from said electrodes, —providing a layer of electrolyte (140) covering said plurality of first electrodes (120) and said intermediate portions (130), and—wherein wetting tension of the surfaces of the intermediate portions (130) is arranged to act more repelling on the electrolyte compared to the wetting tension of the surfaces of the plurality of first electrodes (120), whereby, the electrolyte is concentrated to the surfaces of the plurality of first electrodes (120), and the surfaces of the intermediate portions (130) are substantially free of elec

Abstract: Fabrication of oxide nanowire heterostructures with controlled morphology, interface and phase purity are desired for high-efficiency and low-cost photocatalysis. Disclosed herein is the formation of oxide nanowire heterostructures by sputtering and subsequent air annealing to result in oxide nanowires. This approach allows for fabrication of standing nanowire heterostructures with tunable compositions and morphologies.

Abstract: An in-membrane micro fuel cell comprises an electrically-insulating membrane that is permissive to the flow of cations, such as protons, and a pair of electrodes deposited on channels formed in the membrane. The channels are arranged as conduits for fluids, and define a membrane ridge between the channels. The electrodes are porous and include catalysts for promoting the liberation of a proton and an electron from a chemical species and/or or the recombination of a proton and an electron with a chemical specie. The fuel cell may be provided a biosensor, an electrochemical sensor, a microfluidic device, or other microscale devices fabricated in the fuel cell membrane.

Abstract: A fuel cell membrane electrode assembly is provided comprising a polymer electrolyte membrane which comprises a polymer that comprises bound anionic functional groups, wherein the polymer electrolyte membrane additionally comprises cerium cations. In another aspect, a fuel cell membrane electrode assembly is provided comprising a polymer electrolyte membrane which comprises a polymer that comprises bound anionic functional groups, wherein at least a portion of the anionic functional groups are in acid form and at least a portion of the anionic functional groups are neutralized by cerium cations. In another aspect, a polymer electrolyte membrane is provided which comprises a polymer that comprises bound anionic functional groups, wherein the polymer electrolyte membrane additionally comprises cerium cations, and wherein the amount of cerium cations present is between 0.001 and 0.

Abstract: An electrode for a biplate assembly includes an active material made from a compressed powder 11, and a non-metal carrier 10. A biplate assembly 20 includes electrodes 27, 28 each having a non-metal carrier 10. A method is disclosed for manufacturing an electrode 13 having a non-metal carrier 10. An apparatus 30 is disclosed for manufacturing such an electrode 13. A bipolar battery includes at least one such an electrode 13. The non-metal carrier 10 is preferably a non-conductive carrier.

Abstract: A bipolar plate used in a fuel cell and a method of making a bipolar plate. The sheet is made generally from a stainless steel, and in a more preferable form from a ferritic stainless steel. In one configuration, a stamping or related metal forming tool operation will introduce a negative clearance as a way to move or otherwise reallocate a portion of the material making up the sheet into other portions as a way to reduce stretching, necking, thinning and related thickness deviations associated with the bends formed in the bipolar plate.

Abstract: A membrane electrode assembly includes a membrane, an anode catalyst layer and a cathode catalyst layer. The anode catalyst layer is on a first side of the membrane and the cathode catalyst layer is on a second side of the membrane, wherein the second side of the membrane is opposite the first side of the membrane along a first axis. The cathode catalyst layer includes agglomerates formed of a catalyst support supporting catalyst particles, an agglomerate ionomer and an inter-agglomerate ionomer. The agglomerate ionomer surrounds the agglomerates and the inter-agglomerate ionomer is in regions between the agglomerates surrounded by the agglomerate ionomer. The agglomerate ionomer is different than the inter-agglomerate. Methods to produce the catalyst layer are also provided.

Abstract: A manufacturing method of a fibrous perovskite-type oxide catalyst includes: a first preparing step; a jetting step; a heating step; and an impregnating step. The first preparing step prepares a first solution by mixing metal salts containing La, Sr, Fe, Co and O elements, a first polymer, a metal salt containing a Zn element and a first solvent. The jetting step jets the first solution by using an electrospinning method to produce a precursor fiber. The heating step heats the precursor fiber to produce a perovskite-type oxide mixed with a Zn oxide. The impregnating step impregnates the perovskite-type oxide with an alkaline solution to remove the Zn oxide.

Abstract: The present invention provides a carbon-cladded composite composition for use as a fuel cell flow field plate or bipolar plate. In one preferred embodiment, the composition comprises a core composite layer sandwiched between two clad layers, wherein (a) the clad layer comprises a conductive carbon or graphite material (e.g., carbon nano-tubes, nano-scaled graphene plates, graphitic nano-fibers, and fine graphite particles); (b) the core composite layer comprises a matrix resin and a conductive filler present in a sufficient quantity to render the composite layer electrically conductive with an electrical conductivity no less than 1 S/cm (preferably no less than 100 S/cm); and (c) the composition has a planar outer surface on each clad side having formed therein a fluid flow channel.

Abstract: A NOx storage material comprises a support, a potassium salt impregnated on the support, the potassium impregnated on the support is promoted with a platinum group metal, and wherein the NOx storage material has an electrical property which changes based on the amount of NOx loading on the NOx storage material. An apparatus for direct NOx measurement includes a sensor coated with the NOx storage material. A method of determining NOx flux in a NOx containing gas comprises exposing the gas to the apparatus and converting a signal developed by the apparatus to a signal representative of the NOx flux.

Abstract: After formation of a silicon nitride gate spacer and a silicon nitride liner overlying a disposable gate structure, a dielectric material layer is deposited, which includes a dielectric material that is not prone to material loss during subsequent exposure to wet or dry etch chemicals employed to remove disposable gate materials in the disposable gate structure. The dielectric material can be a spin-on dielectric material or can be a dielectric metal oxide material. The dielectric material layer and the silicon nitride liner are planarized to provide a planarized dielectric surface in which the disposable gate materials are physically exposed. Surfaces of the planarized dielectric layer is not recessed relative to surfaces of the silicon nitride layer during removal of the disposable gate materials and prior to formation of replacement gate structures, thereby preventing formation of metallic stringers.

Abstract: This description concerns a process of converting textile solid waste into a graphite manufacture and makes it possible both to reduce or totally eliminate the use of virgin textile materials for graphitization and to prepare graphite manufacture, such as simple articles (e.g., fibers, powder, foil, sheets, etc.) and complex shape articles (e.g., blocks, plates, rings, pipes, armors, etc.). Described is a sustainable textile solid waste material management process.

Abstract: Systems and methods drawn to an electrochemical cell comprising a low temperature ionic liquid comprising positive ions and negative ions and a performance enhancing additive added to the low temperature ionic liquid. The additive dissolves in the ionic liquid to form cations, which are coordinated with one or more negative ions forming ion complexes. The electrochemical cell also includes an air electrode configured to absorb and reduce oxygen. The ion complexes improve oxygen reduction thermodynamics and/or kinetics relative to the ionic liquid without the additive.

Abstract: Embodiments relate to a composite for a fuel cell layer including a plurality of electron conducting components, a plurality of ion conducting components each having a first surface and a second surface and wherein each ion conducting component is positioned between two electron conducting components. The electron conducting components and the ion conducting components form a layer and at least one of the ion conducting components or the electron conducting components is geometrically asymmetric in one or more dimensions.

Abstract: In one embodiment, a catalyst assembly includes a substrate including a base and a number of rods extending from the base; a catalyst layer including a catalyst material; and a first intermediate layer including a first coating material disposed between the substrate and the catalyst layer, the first coating material having a higher surface energy than the catalyst material. In certain instances, the number of rods may have an average aspect ratio in length to width of greater than 1. The catalyst assembly may further include a second intermediate layer disposed between the catalyst layer and the first intermediate layer, the second intermediate layer including a second coating material having a higher surface energy than the catalyst material. In certain instances, the first coating material has a higher surface energy than the second coating material.

Abstract: A polymer dispersion comprising one or more proton-conducting polymer materials in a liquid medium, and an electrocatalyst ink comprising one or more electrocatalyst materials and one or more proton-conducting polymer materials in a liquid medium are disclosed. The polymer dispersion and the electrocatalyst ink further comprise a protic acid. Electrocatalyst layers, gas diffusion electrodes, catalyzed membranes and membrane electrode assemblies prepared using the dispersion and/or the ink are also disclosed.

Abstract: A bipolar plate which can be produced particularly economically for a fuel cell, with which a high degree of efficiency is guaranteed over a long service life. The bipolar plate has a core layer consisting of a steel material, the surfaces of said core layer, which are associated with the respective electrolyte carriers of the fuel cell, having a corrosion protection layer, protecting the core layer against corrosion. The corrosion protection layers consist of a metal material and extend on both sides over the whole surface of the core layer. At the same time the corrosion protection layers are in turn coated over the whole surface with an electrically conductive functional coating, which is essentially entirely impermeable for the metal ions emerging from the core layer and/or the corrosion protection layers. The invention likewise relates to at least one fuel cell comprising a bipolar plate according to the invention.

Abstract: A substantially crack-free electrode layer is described. The substantially crack-free electrode layer includes a substrate; and a substantially crack-free electrode layer on the substrate, the electrode layer comprising a catalyst, an ionomer, and a layered silicate reinforcement. Methods of making the electrode layer, electrode ink compositions, and membrane electrode assemblies incorporating the electrode layer are also described.