4761 results about "Hydrotalcite" patented technology

An improved dehydrogenation catalyst bed system for olefin production utilizing classical processing techniques is disclosed. The catalyst bed system comprises a dehydrogenation catalyst comprising an active component selected from an oxide of a metal of Group 4 or Group 5 or Group 6 and combinations thereof and a support selected from aluminum oxide, aluminas, alumina monohydrate, alumina trihydrate, alumina-silica, transition aluminas, alpha-alumina, silica, silicate, aluminates, calcined hydrotalcites, zeolites and combinations thereof mixed with a first inert material selected from any material that is catalytically inactive when subjected to reaction conditions that can effect dehydrogenation of olefins and that has a high density and high heat capacity and that is not capable of producing heat during any stage of the dehydrogenation process, and the dehydrogenation catalyst plus the first inert material then being physically mixed with a secondary component comprising a heat-generating inert material and a carrier capable of supporting the heat-generating inert material, wherein the secondary component is catalytically inert with respect to dehydrogenation reactions or to cracking or to coking and generates heat after being exposed to reducing and / or to oxidizing reaction conditions.

The invention discloses a graphene with a porous structure and a preparation method of the graphene. The porous grapheme consists of a single-layer or multi-layer graphene structure unit, the single-layer or multi-layer grapheme structure unit has a pore-shaped structure (pore diameter is 0.1-200 nm) and a large specific surface area (300-2000 m<2> / g), thus the graphene has potential application value in the aspects of super-capacitors, conductive filling materials and the like. The preparation method of the porous grapheme is characterized in that MgO, Mg(OH)2, Al2O3, Al(OH)3, hydrotalcite compounds and / or corresponding calcined products of the substances are used as catalysts, or MgO, Mg(OH)2, Al2O3, Al(OH)3, hydrotalcite compounds and / or corresponding calcined products of the substances are used as carriers so as to further load one or more active components of Fe, Co, Ni and Mo and then the obtained substance is used as the catalyst ( the pore diameter of the catalyst is 1-200 nm, and the specific surface area is 10-300 m<2> / g); and then at the temperature of 300-1000 DEG C, the graphene is prepared by using inert gases such as nitrogen, argon, helium and the like and using a hydrocarbon chemical gas phase deposition method.

A process for producing a high temperature COx-lean product gas from a high temperature COx-containing feed gas, includes: providing a sorption enhanced reactor containing a first adsorbent, a shift catalyst and a second adsorbent; feeding into the reactor a feed gas containing H2, H2O, CO and CO2; contacting the feed gas with the first adsorbent to provide a CO2 depleted feed gas; contacting the CO2 depleted feed gas with the shift catalyst to form a product mixture comprising CO2 and H2; and contacting the product mixture with a mixture of second adsorbent and shift catalyst to produce the product gas, which contains at least 50 vol. % H2, and less than 5 combined vol. % of CO2 and CO. The adsorbent is a high temperature adsorbent for a Sorption Enhanced Reaction process, such as K2CO3 promoted hydrotalcites, modified double-layered hydroxides, spinels, modified spinels, and magnesium oxides.

The invention discloses a granular filtering material for adsorbing and removing heavy metals in water and a preparation method thereof. The granular material consists of the following components in part by mass: 80-120 parts of an adsorbent, 7-14 pats of an additive and 0.5-3 parts of a binding agent, wherein the adsorbent consists of the following components in part by mass: 50-70 parts of coal ash and 30-50 parts of zeolite powder or sea-foam stone powder; the additive consists of the following components in part by mass: 5-7 parts of Mg-Al hydrotalcite, 2-6 parts of biochar and 0.5-1 part of magnesium Lignosulfonate; the binding agent is bentonite. The granular filtering material is prepared through the steps of adsorbent acid modification, biochar preparation, granulation and heat treatment process. According to the invention, the prepared granular filtering material is 3-6 mm in granule size, is large in adsorption capacity and excellent in adsorption effect and can effectively remove heavy metals in water, and no secondary pollutants are dissolved out, so that the granular filtering material can be applied to the treatment on heavy metal micro-polluted water and industrial waste water containing heavy metals, and has good economic and social benefits.

The invention relates to a carrier type solid base catalyst for synthesizing dimethyl carbonate, which belongs to the technical field of catalytic material. The catalyst's formula is KF / M<2+>-N<3+>-(O), wherein M<2+>-N<3+>-(O) represents the composite metal oxide, M<2+> can be divalent metal ion (Mg<2+> or Ca<2+> ) and N<3+> can be trivalent metal ion (Fe<3+> and / or Al<3+>). The catalyst is prepared from potassium fluoride and composite metal oxide at a certain weight ratio by immersing the potassium fluoride into the composite metal oxide, wherein the composite metal oxide is prepared from hydrotalcite precursor and in nucleation / crystallization isolation method by calcining at a certain temperature. The catalyst has the advantages of nanoscaled particle size, high specific surface area and high activity, selectivity in catalytic reaction and simple preparation, and can be reused as it can be centrifugally separated after reacting.

The invention provides a corrosion-inhibiting anionic intercalated hydrotalcite / nano oxide composite material, a preparation method thereof and application of the corrosion-inhibiting anionic intercalated hydrotalcite / nano oxide composite material. The preparation method is as follows: corrosion-inhibiting anions are directly inserted between hydrotalcite layers by the one-step coprecipitation method and the roasting restoring method; the nano oxide is generated by means of in situ synchronization during the process of generation of hydrotalcite crystals by controlling the mixture ratio of divalent metal ions to trivalent metal ions, the pH value of a reaction solution and the reaction temperature; and the corrosion-inhibiting anionic intercalated hydrotalcite / nano oxide composite material with the anti-corrosive function is prepared. The invention is mainly characterized in that the in situ preparation method for the hydrotalcite / oxide composite material provided with a nano lamellar structure improves the release amount of a corrosion inhibitor and reduces the water absorption of a coating by leading into the corrosion inhibitor with the anti-corrosive function and the nano oxide which is generated in situ during the reaction process. The composite material can be used to be pigment of an anti-corrosive metallic coating system, and particularly has potential application value in improving the anti-corrosive performance of a magnesium alloy anti-corrosive coating.

The invention relates to a hydroxyl oxidize iron-nickel-iron hydrotalcite integrated oxygen evolution electrode applicable to alkaline mediums and a preparation method and application thereof. The electrode is applicable to the oxygen evolution reaction in the water-electrolytic hydrogen making process under catalytic alkaline conditions. The hydroxyl oxidize iron-nickel-iron hydrotalcite integrated oxygen evolution electrode and the preparation method and application thereof have the advantages as follows: the nickel-iron hydroxide integrated electrode is shape-controlled, the preparation process is simple and under mild conditions, and the electrode can be used for a water electrolytic tank for hydrogen production from water splitting under external bias potentials; the prepared hydroxyloxidize iron-nickel-iron hydrotalcite integrated oxygen evolution electrode further has a better performance when being used in an alkaline solid polymer electrolyte (AEM) water electrolytic tank; and besides, an extensive utilization value in achieved in regenerative fuel cells (RFC), photoelectro-catalytic devices and electrolytic hydrogen generators.

This invention relates to improvements in inhibiting undesirable discoloring of plastic articles within which silver-based antimicrobials have been introduced. Such a method requires the utilization of very low amounts of acid scavengers or stabilizers such as aluminum-magnesium hydroxycarbonate, otherwise known as hydrotalcite (and not a zinc-based compound). Such hydrotalcites are very low in cost, easy to handle, and, utilized in very low levels in combination with a silver-based antimicrobial within a plastic composition, surprisingly substantially prohibits the generation of unwanted aesthetically displeasing colors.

The catalytically cracking assistant capable of lowering the sulfur content in gasoline is composite oxide including aluminum zinc spinel, homogeneously distributed zinc oxide and at least one optional RE oxide. It is prepared through roasting the mixture of laminar aluminum zinc in hdrotalcite structure and optional RE oxide hydrate. The preparation process is simple, and the assistant has the features of high dispersion, high specific surface area, etc. The assistant after being formed is mixed with conventional FCC catalyst and / or active reinforcing assistant for application in catalytically cracking process, and has the function of lowering the sulfur content in gasoline and excellent hydrothermal stability.

The invention relates to a non-metallic bi-functional oxygen catalyst for graphene / nickel iron type hydrotalcite as well as a preparation method and electric catalytic application thereof to oxygen evolution reaction and oxygen reduction reaction in an alkaline medium. The catalyst takes a micelle as a template, and under the hydrothermal and reducing conditions, the nickel iron type hydrotalcite is assembled onto graphene in sequence to form a spherical porous graphene oxide / nickel iron type hydrotalcite compound. The method comprises the following steps: dispersing graphene oxide and metal salt in the micelle, introducing an alkali source, synthesizing the graphene oxide / nickel iron type hydrotalcite compound under the hydrothermal conditions, and performing hydrazine hydrate reduction on an obtained product to obtain the catalyst. The catalyst prepared by the method has high oxygen evolution and oxygen reduction catalytic activity, good stability and excellent methanol tolerance under the alkaline conditions and is low in cost of raw materials used, simple in preparation method, easy to operate and convenient for large-scale production.

The invention relates to the field of water treatment, specifically to a method for removing metal ions from an aqueous solution by the use of hydrotalcite. The method provided by the invention comprises the step of removing metal ions from an aqueous solution by the use of hydrotalcite. The metal ions, which refer to heavy metal ions or radioactive substance ions, comprise one or more selected from the group consisting of mercury, chromium, lead, arsenic, cadmium, tin, copper and zinc heavy metal ions. The radioactive substance ions comprise uranium, thorium and radium ions. According to the invention, hydrotalcite is applied in metal ions-containing sewage processing, leading to high metal ion removing efficiency and obvious effects. In the meanwhile, raw material sources for the preparation of hydrotalcite are extensive, the cost is low, the preparation method is simple, energy consumption is low and the investment is also low. Therefore, the method provided by the invention has an extensive application prospect.

The invention belongs to the technical fields of material sciences and electro-catalytic hydrogen production, and particularly relates to a nickel-iron hydrotalcite based electro-catalytic oxygen evolution electrode and preparation thereof, wherein the nickel-iron hydrotalcite based electro-catalytic oxygen evolution electrode can be used in an electrolytic water oxygen evolution reaction in an alkaline medium. An electrode system takes a nickel-iron hydrotalcite structure as a catalytic activity center and takes nickel foam as an electrode material; in the alkaline medium, the nickel-iron hydrotalcite based electro-catalytic oxygen evolution electrode can efficiently electrolyze water to prepare oxygen, the overall overcurrent polishing of electrolytic water is reduced greatly, and good stability is showed; according to the preparation technology of the nickel-iron hydrotalcite based electro-catalytic oxygen evolution electrode, a nickel-iron hydrotalcite composite structure is grownon the nickel foam base through an in-situ electrodeposition method; and the resources of required raw materials are wide, the price is low, the technology is mature and stable, operation is easy, convenient and fast, controllability is high, the process does not produce poison, and the nickel-iron hydrotalcite based electro-catalytic oxygen evolution electrode is suitable for mass production andthe industrial electrolytic water reaction.

A process for preparing the efficient sulfur transferring agent used for the catalytic cracking of fume includes such steps as preparing ZnMgAlCe hydrotalcite from the active components (Zn, Mg and Al) and assistant (Ce and V) by codeposition method, preparing V-dipped ZnMgAlCo hydrotalcite by anionic exchange method, proportionally mixing it with kaolin and Al sol, grinding, vacuum drying and calcining. Its advantages are high SOx adsorptivity and desorptivity and high mechanical strength.

The invention relates to an active component morphology controllable loaded noble metal catalyst which uses hydrotalcite as a carrier and is prepared by a precipitation-reduction method. A precipitating agent, a reducing agent, a surfactant, an etchant, a soluble salt solution of +2 and +3-valence metal ions forming the hydrotalcite, and an active component precursor solution are subjected to mixed crystallization, the +2 and +3-valence metal ions are nucleated and grown into the hydrotalcite in an alkaline environment provided by the precipitating agent, and meanwhile, the active component precursor is reduced to 0 valence, and the active component has specific uniform morphology, i.e., the active component morphology controllable loaded noble metal catalyst using the hydrotalcite as the carrier is obtained by one-step reaction. Since the kinetic rate is the key to control the morphology of the active component, and different reducing agents, surfactants and etchants can affect the dynamic process of reduction of the active component, the active component morphology controllable loaded noble metal catalyst of controllable preparation can be attained by controlling the reducing agents, the surfactants and the etchants.

The invention discloses a preparation method and a catalytic application of a supported type high-dispersion nickel-based alloy catalyst. The preparation method comprises the following steps: by virtue of an in-situ growth method, supporting Ni, M (M=Co, Zn, Cu, Fe, Cr and the like) metal in the form of hydrotalcite on the surface of a microsphere-form gamma-Al2O3 carrier with grain size of 20-40 meshes and in a duct of the microsphere-form gamma-Al2O3 carrier, namely growing lamellar precursor LDHs containing Ni and M metal ions outside and inside a Al2O3 particle to form supported type high-dispersion distribution, converting the lamellar precursor LDHs into a corresponding composite metal oxide by drying and roasting at high temperature, and reducing the composite metal oxide to obtain the supported type high-dispersion nickel-based alloy catalyst with NiM distributed on the outer surface and in the duct of the carrier particle. The supported type high-dispersion nickel-based alloy catalyst is applied to first selective hydrogenation reaction of cracked gasoline, so that the conversion rate, the selectivity and the stability of the catalyst can be effectively improved; and moreover, the supported type high-dispersion nickel-based alloy catalyst can be used for methane reforming, and catalyzing reaction of preparing low-carbon hydrocarbon and alcohol by virtue of CO and CO2 hydrogenation.

A hydrotalcite-based composite thermal stabilizer for PVC and chlorine-contained high polymer is prepared from hydrotalcite, calcium soap and zinc soap through proportionally mixing.

The invention provides composite antibacterial powder and a preparation method thereof. The composite antibacterial powder contains nano silver, zinc and nonmetallic minerals such as nano calcium carbonate or nano hydrotalcite, nano titanium oxide and nano bentonite and the like serving as carriers, wherein the content of the silver is 10 to 20 mass percent, and the content of the zinc is 20 to 40 mass percent. The composite antibacterial powder has high bactericidal factor content, is more convenient in compatibility and application, and saves the cost; the particle diameter of the bactericidal factors is nano-scale, so that the bactericidal capability is stronger; the composite antibacterial powder has illumination resistance, does not change color, and has high temperature resistance, good slow-release property and long-acting property; and the preparation method is simple in process, time-saving, labor-saving and high in production efficiency. The composite antibacterial powder serving as an antibacterial agent can be widely applied to various building materials, glass, coating (containing powdery coating), wood, paper and products thereof, plastics, plastic cement, daily ceramic, chemical materials, various home appliances, daily chemical products, textiles and the like.

The invention discloses a gahnitem, zinc oxide and nickel zinc nano-composite photocatalytic material which has a high specific surface area and a mesoporous structure and is prepared by roasting at high temperature by taking ternary hydrotalcite as a precursor. The material is used for the adsorption and the degradation of organic pollutants. The photocatalytic material is prepared by taking zinc nitrate, nickel nitrate, aluminum nitrate, sodium carbonate, sodium hydroxide and the like as raw materials; preparing the raw materials into salt solutions and alkali solutions respectively; mixing the solutions by using a constant-flow pump at the temperature of 80 DEGC with magnetic stirring, transferring the mixed solution into a hydrothermal reaction kettle; performing hydrothermal treatment at 130 to 180 DEG C; performing suction filtration, washing and drying to the precursor; roasting the precursor in Muffle furnace for 2 to 6 hours at the temperature of 400 to 600 DEG C to obtain the product, wherein the specific surface area is greater than 150 m<2>.g<-1>. The photocatalyst disclosed by the invention has regular shape, large specific surface area, and super-high capacity for adsorbing and degrading organics, and can be reused; the raw materials for preparing the composite photocatalyst are abundant, the cost is low, and the process is simple.

The invention discloses a preparation method of two-dimensional nano-graphene. The method includes: mixing acrylic acid and water according to the volume ratio of 1:1-1:2, adding hydrotalcite particles passing a sieve 20-50 in mesh into acrylic acid solution according to the quantity that each gram of hydrotalcite corresponds to 3-5mmol of the acrylic acid, stirring at the temperature of 60-70 DEG C, ageing, separating particles, adding the particles into isopropanol solution, adding ammonium persulfate, heating to 60-90 DEG C for reaction for 8-10h, drying at the temperature of 70-90 DEG C, grinding, and passing a sieve 20-40 in mesh to obtain powder; heating the power to 600-700 DEG C in vacuum, calcining for 2-4h, adding calcined powder into hydrochloric acid solution 20%-40% in concentration, stirring under the protection of nitrogen, precipitating, separating and drying; and heating an obtained product to 2000-2500 DEG C in vacuum, subjecting the product to heat treatment for 3-6h and cooling so that the two-dimensional nano-graphene is obtained. The method is simple in material sources and simple and mild in process.

The invention relates to the technical field of chemical stabilizers, in particular to a transparent environment-friendly calcium zinc stabilizer and a preparation method thereof. The transparent environment-friendly calcium zinc stabilizer is prepared from the following raw materials in percentage by mass: 10 to 30 percent of calcium salt main stabilizer, 10 to 30 percent of zinc salt main stabilizer, 30 to 50 percent of hydrotalcite, 10 to 20 percent of lubricant, 1 to 5 percent of antioxidant, 1 to 5 percent of ultraviolet absorber and 1 to 5 percent of auxiliary stabilizer. The preparation method for the transparent environment-friendly calcium zinc stabilizer comprises the following steps of: adding the raw materials into a high speed stirrer in three stages, jointly stirring at the temperature of between 55 and 56DEG C for 30 minutes, and making the rotating speed of the stirrer 1,000-1,500r / min. The prepared transparent environment-friendly calcium zinc stabilizer has high heatresistance, high transparency and copper rust resistance.

The invention discloses a fire-extinguishing agent. The fire-extinguishing agent is prepared by uniformly mixing hydrophilic solid powder and water or an aqueous solution, adding hydrophobic solid particles and then carrying out mixing and dispersing, wherein the hydrophilic solid powder is one or more of magnesium hydroxide powder, aluminum oxide powder, aluminum hydroxide powder, magnesium carbonate powder, calcium carbonate powder, calcium hydroxide powder, zinc borate powder, montmorillonoid powder, hydrotalcite powder, hydrotalcite like compound powder, fly ash powder, diatomite powder, mica powder and attapulgite powder. The fire-extinguishing agent disclosed by the invention can exert stifling, cooling, separating and chemically restraining functions at the same time, and has the advantages of no toxicity, small environment pollution, high fire extinguishing efficiency and the like. According to the fire-extinguishing agent disclosed by the invention, the hydrophilic solid powder with a certain fire extinguishing performance and smaller solubility in water is added into a water phase so as to reduce the using amount of water-soluble substances, thus the cost of the fire-extinguishing agent is reduced when higher fire-extinguishing efficiency is kept, and the fire-extinguishing agent is easier to clean after being used for extinguishing fire.

A low temperature copper / zinc / aluminum water gas shift catalyst is described. The catalyst is formed from a precursor, wherein the precursor includes aluminum in the form of hydrotalcite and aluminum separate from the hydrotalcite. A method of making the catalyst and a process for using the catalyst are also described.

The invention provides a supported bimetal nanocrystal catalyst which is a binary bimetal catalyst taking aluminum oxide as a supporter and is abbreviated to P-M / MgO-AlO3, wherein P represents noble metal such as Pd, Au, Pt, Ag and the like, and M represents one or two of metal cations such as Cu<2+>, Zn<2+>, Ni<2+>, Ga<3+> and Fe<3+>. The particle size of the P-M bimetal nanocrystal is 2-10 nm, the dimension distribution is narrow, the nanocrystal particles are highly dispersed on the surface of the supporter uniformly and stably, and the crystal form is complete. The preparation method of the catalyst comprises the following steps: preparing soluble Mg<2+> salt for MgMAl-LDH (layered double hydroxide) preparation and an endogenous active metal salt solution into a mixed solution; then simultaneously adding precipitant and the aluminum oxide supporter into the reaction system; enabling hydrotalcite to grow on the surface of the aluminum oxide supporter through an in-situ growth method; supporting exogenous active metal through a wet impregnation method; and performing high-temperature reduction on the obtained catalyst precursor under a reducing atmosphere, thus obtaining the supported bimetal nanocrystal catalyst which is stably and highly dispersed.

A supported non-noble metal catalyst used for preparation of an azo compound from an aromatic nitro compound by hydrogenation coupling is disclosed, an active component of the supported non-noble metal catalyst is any one or more than two of Co, Mn, Fe, Ni and Cu, a carrier is a nitrogen-doped carbon-inorganic oxide composite, the content of the active component in the catalyst is 0.1-15wt%, and an inorganic oxide is any one of alumina, aluminum hydroxide, magnesium oxide, magnesium hydroxide, silica, SBA-15, magnesium aluminum hydrotalcite, titanium oxide and cerium oxide. A preparation process is as follows: the active component and a nitrogen-containing complex are together impregnated on the inorganic oxide, and then calcined at certain temperature. The catalyst has excellent catalytic performance in the preparation of the azo compound from a nitro compound by selective hydrogenation coupling one-step method. The catalyst is simple in preparation, and has high catalytic activity and stability.

The invention discloses a PVC hydrotalcite- rare earth- calcium zinc stabilizing agent and the method for preparing the same, which in detail erlates to plastic composite stabilizing agent and the preaparing method, belonging to chemical field. The main component for stabilizing comprises column- supported hydrotalcite, unsaturated rare earth, and epoxy aliphatic acid calcium zinc, and it is prepared through chemical synthesis, reformed treatment and optimization compound. The product is characterized by outstanding thermal stabilizing effect, good first stage coloring property, sound plasticizing property, good transparenty, weatherability, improved quality, high effeciciency, no toxicity, no pollution, low cost. It can replace expensive organotin thermal stabilizing agent and is widely used in PVC product preparation, such as water- supply pipes, section bar, transparent granulate, film, medical apparatus, toy, fridge stamp and box sheet material.

The invention relates to a heavy-metal ion absorber, which is the baked product of binary hydrotalcite, wherein the formula of binary hydrotalcite is A2+(1-x)B3+x(OH)2(CO32+)x / 2 .mH2O, while 0 B01J 20 / 08 C02F 1 / 28 C02F 1 / 62 3 4 1 2006 / 10 / 20 1962046 2007 / 5 / 16 000000000 Shandong University 250061 Su Jixin Zhang Weihong Wang Xiaopeng Yin Jing Qu Wen Pan Qi xude shan 37219

The invention relates to a process for producing board which comprises providing an aqueous suspension comprising cellulosic fibres; adding hydrotalcite to the suspension; dewatering the obtained suspension to provide a (i) single ply board. The invention further relates to board comprising one or more plies containing cellulosic fibres, wherein the board further comprises hydrotalcite distributed throughout at least one of said one or more plies.

The present invention discloses rod-shaped magnesia alumina hydrotalcite-like compound (HTlc) as one new shaped hydrotalcite-like compound. The rod-shaped magnesia alumina hydrotalcite-like compound has the crystal structure of hydrotalcite and chemical expression of [MII(1-x)MIIIx(OH)2]x+[An-x / n]x-mH2O, where, MII and MIII are bivalent and trivalent metal cation separately, An- is interlayer anion, x is the molar fraction of MIII in HTlc, m is the molar fraction of interlayer crystalline water. It is prepared through a traditional co-precipitation process under the induction of soft template or shape regulating agent sodium stearate. It has simple preparation process and low cost, and may be used as rubber and plastic additive, fire retardant, pesticide release controlling agent, etc.

The invention relates to fully-degradable heat-insulation mulch and a preparation method thereof. The fully-degradable heat-insulation mulch comprises the following components in parts by mass: 30-60 parts of PBAT (poly(butylene adipate terephthalate), 10-30 parts of polylactic acid, 10-30 parts of starch, 5-10 parts of plasticizer, 0-2 parts of chain extender, 5-10 parts of fillings, 5-20 parts of fully-degradable hydrotalcite master batch and 0-5 parts of fully-degradable color master batch. The preparation method of the fully-degradable heat-insulation mulch comprises the following steps of: carrying out extruding pelletizing on hydrotalcite powder and the PBAT in double screws to obtain the hydrotalcite master batch, preparing a material for the fully-degradable heat-insulation mulch from the hydrotalcite master batch, the PBAT, the starch, the polylactic acid, the plasticizer, the chain extender and the fillings according to a specific production process, and finally carrying out secondary processing on the obtained material in coordination with the fully-degradable color master batch to obtain the fully-degradable heat-insulation mulch. The fully-degradable heat-insulation mulch disclosed by the invention has the capability of completely degrading in soil and is good in heat insulation property, low in production cost, favorable in economic and social benefits and worthy of popularization and application.