96 results about "Dithiocarbamate" patented technology

The invention discloses a dithiocarbamate monomer, a holographic recording medium, a preparation method and a related device, the structural general formula of the monomer is as shown in G1 and G2, R1 represents any one of hydrogen, halogen and C1-C4 alkyl, R3 represents any one of hydrogen, halogen and C1-C4 alkyl, A1 represents C1-C4 alkyl, A2 represents hydrogen or methyl, n is a positive integer, and n = 1-10. The dithiocarbamate monomer provided by the invention has high refractive index, and the holographic recording medium with high sensitivity, high diffraction efficiency and high refractive index modulation degree can be obtained by applying the dithiocarbamate monomer to preparation of the photopolymer holographic recording medium; holographic recording media can be used to prepare volume holographic gratings, holographic optical elements, and optical devices.

The application discloses an automatic control method for oxidation flocculation parameters in mancozeb wastewater treatment, and belongs to the technical field of industrial wastewater treatment and automatic control. In view of the problem that the existing process relies on manual experience and the oxidation and flocculation stages are improperly connected, the multifunctional modified material containing dithiocarbamate salt groups, quinone groups and pre-complexed manganese and zinc ions is prepared first; the material and hydrogen peroxide are synchronously added in the acid oxidation stage, and the control system monitors the redox potential change rate in real time; when the redox potential reaches the preset threshold value and the characteristic change point with the first derivative of zero or the change from positive to negative appears and is maintained for the preset maintenance time, the system is automatically adjusted to be alkaline, the modified material triggers the net capture and chelation crosslinking reaction, and finally solid-liquid separation is carried out; the polymer skeleton is protected from indiscriminate attack of free radicals, the problem of drug antagonism is overcome, and the stable and up-to-standard effluent quality is realized.

Bicycle chain lubricant comprising base oil, a tackifier, and an anti-wear additive being either zinc dialkyl dithiophosphates (ZnDTP), molybdenum dithiocarbamates (MoDTC), or a mixture of both. The b

This invention belongs to the field of mineral flotation technology, and discloses a flotation collector for non-ferrous metal sulfide ores, its preparation method, and its application. The collector uses O,O-dialkyldithiophosphate as a starting material, and reacts sequentially with a halocarboxylic acid ester, hydrazine hydrate, potassium hydroxide, and carbon disulfide in anhydrous ethanol in a three-step reaction to obtain the target product, O,O-dialkyldithiophosphate hydrazide-N′-dithiocarbamate potassium. Its molecular structure simultaneously contains three active groups: a dithiophosphate group, an hydrazide group, and a dithiocarbamate group. This invention achieves efficient process connection and smooth transition by optimizing the material ratio, temperature, and time of each reaction step, and has advantages such as mild reaction conditions, simple operation, few side reactions, high yield, and stable product. The prepared collector exhibits excellent collecting performance and good selectivity for non-ferrous metal sulfide ores such as chalcopyrite, and is suitable for widespread application in sulfide ore flotation processes.

The invention relates to the field of lubrication of ball screws, in particular to long-life creep-resistant lubricating grease for a high-precision ball screw, which comprises the following components in parts by weight: 65 parts of polyolefin, 5-10 parts of pentaerythritol ester, 5-10 parts of isocyanate, 2-5 parts of amine chain extender, 5 parts of PTFE (polytetrafluoroethylene), 1.0-1.5 parts of diphenylamine, 0.1-0.5 part of 2, 4-diphenyl-1, 3-pentanediol monoisobutyrate, 0.1-0.5 part of antioxidant, 0.1-0.5 part of antioxidant and 0.1-0.5 part of lubricant. The composite material is prepared from the following components in parts by weight: 0.5 to 1 part of 2, 6-butylated hydroxytoluene, 1.5 to 2 parts of molybdenum isocaprylate, 0.5 to 1 part of molybdenum bis (2-ethylhexyl) dithiocarbamate, 1 to 2 parts of zinc dialkyl dithiophosphate, 3 parts of calcium petroleum sulfonate, 1 to 1.5 parts of polyisobutene, 0.2 to 0.5 part of benzotriazole and 0.1 to 0.3 part of polymethacrylate. The isocyanate comprises HDI and IPDI, and the amine chain extender comprises TETA and TEPA. According to the invention, isocyanate and the amine chain extender react to form a polyurea macromolecular chain, and a high-energy hydrogen bond network is formed, so that the lubricating grease has relatively high creep resistance; the anti-creep performance is further enhanced through cooperation with the PTFE particles; meanwhile, through cooperation with diphenylamine, the oxidation resistance is promoted, the consumption is reduced, and the service life of the lubricating grease is longer.

This invention proposes a lubricating oil composition for a four-stroke engine specifically designed for unmanned aerial vehicles (UAVs) and its preparation method. The lubricating oil composition for a four-stroke engine of this invention comprises the following components: (A) a nitrogen-containing organoboron compound; (B) an alkyl diphenylamine; (C) polyisobutylene succinimide; (D) sulfonates and / or sulfurized alkylphenol salts; (E) zinc dialkyl dithiophosphate; (F) dialkyl dithiocarbamate; (G) polymethyl methacrylate; and (H) a base oil in a major amount. The structure of the nitrogen-containing organoboron compound is shown in formula (I) and / or formula (II), with the definitions of each group provided in the specification. The lubricating oil composition for a four-stroke UAV engine of this invention exhibits excellent extreme pressure anti-wear, anti-oxidation, and detergency properties, effectively suppressing the increased wear caused by the high power-to-weight ratio and harsh lubrication conditions of four-stroke UAV engines.

The application discloses a hydrogen fuel engine oil composite additive composition, which comprises 3.0-5.0% high-alkali-value magnesium sulfonate, 12.0-20.0% low-alkali-value calcium sulfonate, 3.0-4.0% high-alkali-value calcium sulfide alkyl phenol, 2.0-5.0% amine type antioxidant, 2.0-5.0% phenol type antioxidant, 2.0-5.0% alpha-naphthylamine, 1.5-3.0% dibutyl dithiocarbamic acid ester, 1.5-3.0% anti-wear agent, 0.2-0.5% fatty amide, and the rest is ashless dispersant. The application further discloses a hydrogen fuel engine oil composition, which comprises 14.4-15.5% composite additive composition, 7.0-9.0% tackifier, 0.2-0.5% pour point depressant, and the rest is base oil. The composite additive improves the demulsification performance of the hydrogen fuel engine oil under high-temperature and high-pressure conditions, and further improves the water separation property and other comprehensive use performances of the oil product.

A method for producing a fluoropolymer by solution polymerization or dispersion polymerization, the method including: in the presence of an initiator, a chain transfer agent, and a solvent, (i) homopolymerizing tetrafluoroethylene; or (ii) randomly copolymerizing tetrafluoroethylene and at least one of a monomer represented by the following formula (1) or a monomer represented by the following formula (2). The chain transfer agent includes at least one selected from dithioester compounds, dithiocarbamate compounds, trithiocarbonate compounds and xanthate compounds. The fluoropolymer contains 50 to 100 mol % of a polymerized unit based on the tetrafluoroethylene. The formula (1): CF2═CR1R2 wherein R1 and R2 are as defined herein, the formula (2): CH2═CR3R4 wherein R3 and R4 are as defined herein.

The invention belongs to the technical field of labor protection articles, and particularly relates to an environment-friendly butyronitrile glove and a preparation method thereof.The environment-friendly butyronitrile glove comprises a glove core, an environment-friendly butyronitrile rubber layer is fixed to the outer surface of the glove core in a gum dipping mode after the glove core is soaked in pretreatment liquid, and the environment-friendly butyronitrile rubber layer contains carboxyl butyronitrile latex; the environment-friendly butyronitrile rubber material is prepared by firstly pretreating carboxyl butyronitrile rubber latex and then mixing the pretreated carboxyl butyronitrile rubber latex with sodium dodecyl benzene sulfonate, a 5% potassium hydroxide solution, a 50% zinc oxide dispersion liquid, a 50% sulfur dispersion liquid, a 50% zinc dimethyldithiocarbamate dispersion liquid, a 50% titanium dioxide dispersion liquid, color paste and an alkali swelling type thickening agent. According to the invention, triple synergy of standard environmental protection, stable performance and controllable cost is realized, the industrial problem that protection performance, environmental benefits and economical efficiency are difficult to consider in the prior art is solved, and the dual requirements of modern environmental protection and use experience are met.

Some of the resin compositions are ultraviolet light or thermally curable, while others are ultraviolet light curable. One example of the ultraviolet light or thermally curable resin composition consists of a predetermined mass ratio of a (meth)acrylate cyclosiloxane monomer and a non-siloxane (meth)acrylate based monomer ranging from about >0:<100 to about 80:20; from 0 mass % to about 10 mass %, based on a total solids content of the resin composition, of an initiator selected from the group consisting of an azo-initiator, an acetophenone, a phosphine oxide, a brominated aromatic acrylate, and a dithiocarbamate; a surface additive; and a solvent.

The invention discloses a dithiocarbamate nickel (II) complex as well as a preparation method and application thereof, the chemical formula of the nickel (II) complex is [NiIILCl], and L is (E)-2-(phenyl (pyridine-2-yl) methylene) hydrazino methyl dithioformate. The nickel (II) complex is mild in synthesis condition and high in target yield. In-vitro MTT activity evaluation proves that the introduction of copper ions has a synergistic effect on the anticancer activity of the nickel (II) complex, so that the activity of the nickel (II) complex is improved from a micromole level to a nanomole level, and the amplification is as high as 200 times or more. Cell scratch experiments prove that the nickel (II) complex and copper (II) ions are combined for use, so that the migration resistance is achieved. A nickel (II) complex and copper ion combination strategy provided by the invention not only has a direct killing effect on cancer cells, but also can effectively inhibit the migration ability of the cancer cells, and shows huge application potential in the field of cancer treatment.

The invention belongs to the technical field of lubricating materials and particularly relates to wide-temperature-range lubricating grease for a helicopter transmission system as well as a preparation method and application of the wide-temperature-range lubricating grease. The wide-temperature-range lubricating grease for the helicopter transmission system comprises the following components: base oil, a thickening agent, a tribological property improver, an antioxidant, an adhesive and an antirust agent, the tribological performance improver is prepared from oxymolybdenum thiodibutyl dithiocarbamate, antimony dibutyl dithiocarbamate, tricresyl phosphate and bismuth sulfide according to the mass ratio of (3 to 5) to 1 to (1 to 3) to (0.1 to 1.5). The wide-temperature-range lubricating grease for the helicopter transmission system, provided by the invention, has outstanding high-temperature oxidation resistance, excellent extreme-pressure wear resistance and high-temperature performance and excellent low-temperature starting and operating torque, and can meet the use requirements of a lubricating grease product for the helicopter transmission system on wide temperature range and high load.

The application provides application of n-methyl-n-pentyl thiourea as a collector in a sulfur-oxygen mixed copper-cobalt ore and a synchronous flotation method, and relates to the technical field of flotation. In view of problems of the traditional sulfur-then-oxygen process, such as a complicated process, a complex process, and influence of changes of oxidation and sulfidation rates on the flotation effect of the sulfidized copper-cobalt ore, the application provides a new flotation process and reagent, does not need to use a sulfidation agent for sulfidation, simultaneously floats and sulfidizes and oxidizes the copper-cobalt ore, and simultaneously floats the oxidized and sulfidized copper-cobalt ore by using an activator sodium dimethyl dithiocarbamate and a chelate collector n-methyl-n-pentyl thiourea. The flotation process of the application is simple, efficient, clean and efficient, and provides a new method, a new process and a new way for the flotation of the complex sulfur-oxygen mixed copper-cobalt ore.

The application discloses a segmented leaching and adsorption reinforced silver recovery system and method, and belongs to the technical field of metallurgy. The system comprises two pre-leaching tanks, two silver adsorption tanks and at least four gold adsorption tanks connected in series, and the leaching tanks are connected in series. The silver adsorption tanks are filled with modified silver special adsorption carbon, and the gold adsorption tanks are filled with gold active carbon. The last gold adsorption tank is connected with the feeding end of a post-leaching thickener, the overflow supernatant of the post-leaching thickener is connected with the feeding end of a precipitation tank, and the discharging end of the precipitation tank is connected with the pre-leaching tank through a cyanide-resistant centrifugal pump. The system further comprises air lifters respectively inserted into the second silver adsorption tank and the last gold adsorption tank, and the air lifters are sequentially connected with a linear vibrating screen, a silver carbon desorption column or a gold carbon desorption column and an electrodeposition tank. The modified silver special adsorption carbon is loaded with a dithiocarbamate salt group on the surface. The system solves the problems of low silver recovery rate, long carbon extraction period, high reagent consumption and gold-silver adsorption competition in the existing whole mud cyanidation carbon pulp process.

The invention discloses a combined reagent for mixed flotation of copper-nickel sulfide ores and application, and belongs to the technical field of mineral flotation reagents. The combined medicament is composed of a component 1 (amine compound) and a component 2 (composite oil phase) which are independently subpackaged, and the component 2 is prepared by compounding sulfur-nitrogen ester, 2 # oil, N, N-dialkyl dithiocarbamate and a nonionic surfactant. Through step-by-step addition of the two components and synergistic compounding of the interior of the component 2, the agent has high collecting performance and good foaming performance, and the recovery rate of pentlandite and chalcopyrite is remarkably increased; meanwhile, the problems that a conventional medicament is easy to crystallize at low temperature and poor in flowability are effectively solved, and the medicament system is simple and low in cost. The method is particularly suitable for bulk flotation of the copper-nickel sulfide ore and has a wide industrial application prospect.

The invention discloses a preparation method of sulfoalkyl (methyl) acrylate, which is characterized in that (methyl) acrylic acid and hydroxyalkyl sulfonic acid are used as raw materials, an acidic resin catalyst is adopted, and the sulfoalkyl (methyl) acrylate is prepared by reaction in the presence of a solvent and a compound polymerization inhibitor, the compound polymerization inhibitor is a combination of a phenolic compound and at least one of the following compounds (A)-(D): (A) a quinone compound; (B) a nitroxide radical compound; (C) an inorganic salt compound; and (D) copper N, N-di-n-butyl dithiocarbamate. By using the method, the polymerization side reaction in the reaction process can be effectively inhibited, and the method has the advantages of short reaction time, simple post-treatment and low content of the hydroxyalkyl sulfonic acid dimer in the product.

This invention relates to the field of mineral processing flotation reagents, specifically disclosing a high-efficiency collector for the flotation of sphalerite and its preparation method. The high-efficiency collector provided by this invention achieves synergistic enhancement of the functions of each component by compounding isopropyl xanthate, dialkyl dithiocarbamate, and mercaptoacetate, and introducing a designed and synthesized polymeric synergist. The three basic collector components together constitute a dense and stable primary hydrophobic adsorption layer. The introduced synergist, on the one hand, enhances the adsorption strength and selectivity on the surface of sphalerite through multiple functional groups; on the other hand, its grafted hydrophilic polymer chains can form steric hindrance at the mineral-water interface and regulate local hydrophilicity and hydrophobicity, thereby further optimizing the hydrophobic state of the mineral surface and inhibiting gangue inclusions. The composite reagent provided by this invention improves the recovery rate of useful minerals while ensuring concentrate quality.

The invention provides a rare-earth slow-release fertilizer as well as a preparation method and application thereof. The rare-earth slow-release fertilizer comprises rare-earth slow-release particles and a basic fertilizer, the rare earth sustained-release particle comprises an inner core formed by rare earth ions and a chelating agent, and a coating layer coating the inner core, the chelating agent comprises unsubstituted and / or alkyl substituted dithiocarbamate; the basic fertilizer comprises any one or a combination of at least two of nitrogenous fertilizer, phosphatic fertilizer or potash fertilizer. The rare earth slow-release fertilizer provided by the invention realizes gradient release of rare earth ions, has slow-release stability in a wide pH range, reduces soil rare earth loss, improves the bioavailability of the rare earth ions, and reduces the risk of environmental pollution.

The invention discloses a method for flotation of copper oxide or copper oxide cobalt ore by using calcium-magnesium-rich high-alkalinity tailing backwater, and belongs to the technical field of ore dressing. The method comprises the following steps: crushing, grinding and mixing copper oxide or copper oxide cobalt ore raw ore to obtain ore pulp; a copper-cobalt ore inhibitor (ammonium dithiocarbamate and sulfamate-containing) and a calcium-magnesium gangue mineral collecting agent are added into the ore pulp, reverse flotation is carried out, a foam product is calcium-magnesium gangue minerals, and a tailing product is copper oxide or copper oxide cobalt concentrate; wherein water used in the processes of ore grinding, size mixing and reverse flotation is calcium-magnesium-rich high-alkalinity tailing backwater. According to the method, the flotation recovery rate of the copper oxide or copper oxide cobalt ore is increased, direct and efficient utilization of the calcium-magnesium-rich high-alkalinity tailing backwater is achieved, and the method has good industrial application value and environmental friendliness.

Disclosed is a method comprising combining the following components to form a platinum (II) dithiocarbamate complex in a solvent: (i) a platinum (0) complex; (ii) tetrahydrocarbyl thiuram disulfide; and (iii) a solvent. The method may also include separating the platinum (II) dithiocarbamate complex from a solvent to separate the platinum (II) dithiocarbamate complex. The method can also include preparing a curable silicone composition by combining the platinum (II) dithiocarbamate complex with a vinyl functional silicone and a silyl hydride functional silicone to form a curable composition.

The invention relates to the technical field of stay cable bridge construction, and particularly discloses a novel high polymer material for a viscoelastic damper. Comprising the following raw materials in parts by weight: 45 to 55 parts of polylactic acid-polycaprolactone segmented copolymer, 10 to 12 parts of low molecular weight sulfydryl-terminated polyisobutene, 15 to 18 parts of medium molecular weight sulfydryl-terminated polyisobutene, 1 to 1.7 parts of zinc dithiocarbamate, 2 to 3.3 parts of trimethylolpropane borate, 6 to 9 parts of KH550 modified expanded graphite, 2 to 3 parts of KH550 modified carbon nanotube, and 3 to 5 parts of methoxypolyethylene glycol. Binary sulfydryl-terminated polyisobutene is adopted to provide a viscosity and elastic basis, the polylactic acid-polycaprolactone block copolymer optimizes the regularity of a system structure, zinc dithiocarbamate and trimethylolpropane borate form a synergistic crosslinking effect, and all the components are matched with one another to form a stable composite system, so that the adhesive force of the adhesive is improved, and the adhesive force of the adhesive is improved. Therefore, the resistance and absorption capacity of the material to external loads are improved.

The invention relates to optochemical ion sensors having an antifouling coating containing zinc ethylenebis(dithiocarbamate) as a biocidal active substance in a matrix of a water-insoluble, water-swellable hydrogel which is ion-permeable in the swollen state, and to a method for the production thereof.

The invention relates to the technical field of power cable materials, and particularly discloses a waterproof corrosion-resistant cable material, a preparation method thereof and a cable. The waterproof corrosion-resistant cable material is prepared from the following raw materials: 55 to 75 parts of a modified polyethylene-polyvinyl chloride blend, 5 to 10 parts of an aminated graphene / montmorillonite intercalation composite material, 5 to 15 parts of acrylate rubber, 1 to 3 parts of carbon nanotubes, 2 to 4 parts of nano zinc oxide, 1 to 2 parts of an antioxidant, 0.5 to 1.5 parts of a lubricant, 3 to 6 parts of a plasticizer and 2 to 5 parts of a compatilizer, the modified polyethylene-polyvinyl chloride blend is obtained by carrying out cross-linking modification on a polyethylene-polyvinyl chloride blend by using zinc dithiocarbamate. The cable material disclosed by the invention has excellent waterproof performance and corrosion resistance, and the application scene of the cable material is obviously expanded.

This invention belongs to the field of new materials and discloses a method for preparing high-purity lithium sulfide material. The method involves using ammonium dithiocarbamate as a sulfur source and lithium hydroxide or lithium carbonate as a lithium source, premixing them in a predetermined ratio to obtain precursor A. Precursor A is then placed in a ball mill and mixed at a certain milling intensity to obtain precursor B. Precursor B is then sintered in a sintering furnace to obtain high-purity lithium sulfide material. This invention's preparation method has low production costs, a green and safe preparation process, and yields high-purity lithium sulfide material.

The application discloses a preparation method and application of a dithio-carbamate compound / polypolydithio-carbamate compound. The dithio-carbamate compound / polypolydithio-carbamate compound is obtained by reacting an amine compound, an isonitrile compound, carbon disulfide and a mercaptan compound in an organic solvent in the presence of a base. The raw materials used in the application are all industrial raw materials, which can be directly purchased and have low cost, and can be produced in a large scale of gram grade. The polymerization operation is simple, the yield is high, the reaction condition is mild, no metal catalyst is needed, the reaction can be carried out at room temperature and in the air, and no toxic and harmful by-products are generated. The polypolydithio-carbamate compound obtained by the application also has excellent mechanical properties and luminescent properties, and can be applied to the fields of mechanical materials and optoelectronic devices, thereby promoting the further development of the polypolydithio-carbamate compound.

The invention belongs to the field of construction of DEL libraries, and particularly relates to a method for preparing an On-DNA 2-hydroxydithiocarbamate structure compound. Comprising the step of reacting On-DNA secondary amine with carbon disulfide and an epoxy compound at a certain temperature and under a solvent condition to generate an On-DNA 2-hydroxydithiocarbamate structure compound. According to the preparation method disclosed by the invention, tens of thousands of compounds with On-DNA dithiocarbamate structures can be rapidly synthesized, the chemical space of On-DNA is enriched, and the diversity of On-DNA compounds is increased. In the field of new drug research and development, the high-throughput screening hit rate of biological targets can be improved, and the discovery efficiency and possibility of lead compounds are remarkably improved.

This invention provides a lubricating oil and its application. The lubricating oil includes a base oil, detergent, antioxidant, dispersant, friction reducer, pour point depressant, and viscosity index improver. The friction reducer includes a carbamate and a phosphate ester as shown in Formula 1. The carbamate includes dibutyl dithiocarbamate, with a mass percentage of 0.2% to 0.5% for the dibutyl dithiocarbamate and a mass percentage of 0.1% to 0.3% for the phosphate ester. This lubricating oil possesses excellent high-temperature detergency, soot dispersibility, oxidation resistance, wear resistance, and low friction characteristics, and can simultaneously meet the lubrication requirements of engines and transmission systems, thus achieving standardization of oils used in engines and transmission systems.

The application discloses a soil treatment composition, a preparation method and an application scheme thereof, and discloses a composition comprising methyl isothiocyanate compounds and fluopyram, wherein the methyl isothiocyanate compounds are selected from dithiocarbamates or metam, the weight ratio of the two is 400:1-1400:1, and the weight percentage of active ingredients in the soil treatment composition is 5%-99%. The composition has high activity on a series of nematodes and soil-borne fungal diseases which invade crops, and has significant synergistic performance on Fusarium and Meloidogyne in particular, and meanwhile, the composition can meet the basic prevention and treatment requirements while reducing the amount of application.

The invention provides a diesel engine lubricating oil composition and a preparation method thereof. The diesel engine lubricating oil composition of the present invention comprises: (A) a viscosity index improver; (B) a boronized ashless dispersant and / or a polyisobutylene succinate ashless dispersant; (C) sulfonate and / or sulfurized alkylphenate metal detergents; (D) zinc dialkyl dithiophosphate; (E) a dialkyl dithiocarbamate; (F) an amine type antioxidant; (G) a thiophenol ester type antioxidant; (H) lubricating base oil; wherein the viscosity index improver is a copolymer of methyl acrylic acid C8-C12 alkyl ester, methyl acrylic acid C13-C18 alkyl ester and N-vinyl imidazole. The diesel engine lubricating oil composition has excellent soot dispersion, wear resistance and high-temperature cleaning performance, and can meet the requirements of API CI-4, ACEA E4 and E7-grade high-performance diesel engine lubricating oil.

The application discloses a harmless treatment solidifying agent formula for industrial solid wastes and harmful substances such as heavy metals, and belongs to the technical field of solidifying agent formula preparation, and comprises the following raw materials in parts by weight: waste gypsum 10-15 parts, silicate cement 20-30 parts, slag 20-30 parts, fly ash 20-30 parts, dithiocarbamate 2-5 parts, ferrous sulfate 5-10 parts, bentonite 5-10 parts, diatomite 5-10 parts, and quicklime 2-5 parts. In the application, the recycling of industrial solid wastes such as waste gypsum, slag and fly ash realizes a circular economy mode of treating waste with waste, reduces the raw material cost, and reduces the environmental pressure caused by solid waste storage. The synergistic effect of dithiocarbamate and ferrous sulfate in the formula, in combination with the high specific surface area adsorption characteristics of bentonite and diatomite, can effectively capture and stabilize heavy metal ions, form low-solubility metal sulfide precipitates, and significantly reduce the leaching toxicity of heavy metals.