77 results about "Organic sulfide compound" patented technology

An adsorbent for removing organic sulfide, and a preparation method therefor and a use thereof, relating to the technical field of desulfurization adsorbents. The adsorbent for removing organic sulfide comprises a high-pore-volume core and a coating layer attached to the high-pore-volume core; the high-pore-volume core is obtained by mixing a nonionic surfactant, an alkali metal precursor and / or an alkaline-earth metal precursor, and an aluminum-containing compound and then carrying out forming and drying on same; and the coating layer is formed by an Ag and Ce co-modified high-silicon molecular sieve and a composition Al2(OH)nCl6-n (n=1-5). The adsorbent has the characteristics of high desulfurization efficiency, wide desulfurization range, high desulfurization precision, mild use conditions, long service life and the like, can achieve deep removal of organic sulfur under normal-temperature and normal-pressure conditions, can remove the organic sulfur in raw materials to 10 ppb or below, and is particularly suitable for desulfurization and purification of liquefied petroleum gas or natural gas.

Disclosed in the present invention are a high-temperature ultrahigh-strength high-elongation copper foil for a lithium-ion battery, and a production process therefor. The production process comprises the following steps: step S1, preparing an electrolyte by dissolving raw copper in a sulfuric acid solution to form a dissolved solution, filtering same to remove impurities and then mixing same with a composite additive to obtain the electrolyte, wherein the composite additive comprises an organic sulfide, gelatin, polyethylene glycol, a nitrogen-containing compound, a polyether compound and Cl-; step S2, preparing a primary copper foil by introducing the electrolyte into an electrolytic cell of a crude foil machine via a pipeline and carrying out electroplating to obtain the primary copper foil; and step S3, subjecting the primary copper foil to a surface passivation treatment, drying and winding to obtain an ultrahigh-strength copper foil for a lithium-ion battery. A high-performance additive is introduced to control the grain refinement and uniform distribution of the copper foil, thereby improving the strength and ductility thereof; the thermal stability and strength of the improved copper foil in a high-temperature environment are maintained, thereby ensuring long-term stable operation of the improved copper foil after high-temperature cyclic charging and discharging of a silicon negative-electrode battery.

The invention relates to a modified molecular sieve and a preparation method and application thereof, and the preparation method comprises the following steps: alkali modification: obtaining an alkali modified ultra-stable Y molecular sieve; performing nickel ion exchange for many times to obtain a nickel ion loaded ultra-stable Y molecular sieve; and carrying out cerium ion exchange to obtain the nickel-cerium double-loaded ultra-stable Y molecular sieve. On the basis of an ultra-stable Y-type molecular sieve, a novel modified molecular sieve is prepared through further modification treatment, so that the adsorption performance of the novel modified molecular sieve on organic sulfides such as mercaptan and thioether in oily sewage and oily waste gas is improved, and a more efficient, economical and environment-friendly technical solution is provided for VOCs emission treatment in the petrochemical industry; the method has important application value and market prospect.

The invention relates to the technical field of organic sulfide preparation, in particular to a method for synthesizing and refining dimethyl sulfide (DMS) and dimethyl sulfoxide (DMSO) embedded into a methanol plant, which mainly utilizes high-purity oxygen of an air separation unit of the methanol plant, a high-concentration hydrogen sulfide product of low-temperature methanol washing and part of top gas-phase refined methanol of a pressurizing tower of a methanol rectification device. The production cost of the product is reduced, the added value of the product is improved, and the hydrogen sulfide product of a methanol plant is effectively utilized.

The invention discloses sewage energy-saving treatment equipment for oil-based needle coke production, and belongs to the technical field of oil-based needle coke production. The device comprises a box body, a plurality of fixing pipes are symmetrically and fixedly connected to the side wall of the box body in a penetrating mode, a plurality of box covers are clamped to the upper side of the box body, a plurality of ultraviolet irradiation lamps are fixedly connected in the box body, two baffles are symmetrically and fixedly connected in the box body, and an air flotation machine is fixedly connected to the bottom in the box body. A slag scraping assembly is installed in the box body and comprises a slag scraping plate. In the sewage treatment process, under the action of the ultraviolet irradiation lamp and the catalyst, organic sulfide in sewage can be converted into inorganic sulfide, then under the action of the slag scraping plate, impurities floating on the water surface can be scraped between the baffle and the box body, the simple impurity removal effect is achieved, the structure is simple, and the operation is convenient. The practical effect is good.

The present invention relates to organic sulfides, optical materials such as plastic lenses, prisms, filters, and more particularly to a thiol composition and its application in optical materials. Adding a thiol compound of formula (1) to 2,3-disulfide (2-mercapto)-1-propanethiol or a thiol composition mainly containing the thiol compound, and controlling the content of the thiol compound of formula (1) within a certain range, can effectively solve the problem of impurity points in optical materials prepared mainly using 2,3-disulfide (2-mercapto)-1-propanethiol, and significantly improve the qualified rate of optical materials.

The invention relates to a ZnAl-LDH-based material as well as a preparation method and application thereof in sludge treatment. The ZnAl-LDH-based material is prepared from a divalent metal salt solution and a trivalent metal salt solution through a coprecipitation method, divalent metal comprises Zn and Cu, and trivalent metal is Al; the molar weight ratio of the divalent metal to the trivalent metal is (1-3): 1, and the ratio of the molar weight of Cu to the total molar weight of the divalent metal is (0-0.5): 1. The ZnAl-LDH-based material is used for promoting the organic sulfide in the sludge to be converted into sulfoxide sulfur and sulfone sulfur. Compared with the prior art, a series of ZnAl-LDH-based materials with proper specific surface areas and pore volume structures are prepared, and low-valence organic sulfides in municipal sludge can be promoted to be directionally converted into sulfoxide sulfur and sulfone sulfur; the method has a wide application prospect in the field of improving the high-added-value utilization of organic sulfide-containing wastes such as municipal sludge.

The invention relates to a sulfur isotope detection device system and method for organic sulfides in natural gas, impurities in the natural gas are removed through a preset chemical trap and a hydrogen sulfide adsorption trap coupled with a heating device for use, and the effective enrichment space of the organic sulfides in a cold trap is prevented from being occupied; two stages of cold traps are adopted, so that organic sulfides can be effectively enriched and detected and analyzed; the sulfur isotope detection device system is high in reliability, high in automation degree and easy to operate, sulfur isotope detection and analysis are carried out by combining a chromatography-stable isotope mass spectrometer, and a new way is provided for researching causes, sources and generation mechanisms of sulfur-containing natural gas.

The invention discloses a method for synthesizing an organic sulfide compound, and belongs to the field of organic synthesis. The invention uses an alkenyl sulfide salt shown in formula I as a raw material, and reacts to obtain an organic sulfide compound shown in formula II without metal catalysis. The raw materials of the method of the invention are cheap and easy to obtain, and no metal catalyst is required. The method is green, environmentally friendly and pollution-free, and has the advantages of a wide range of substrates, high yield, simple operation, and easy separation and purification of products. #imgabs0#

The invention relates to the technical field of copper foil preparation, in particular to a high-elongation ultrathin lithium battery copper foil and a preparation method and application thereof.The preparation method comprises the following steps that S1, a copper raw material, sulfuric acid and deionized water are dissolved to obtain a copper sulfate solution, the copper sulfate solution is subjected to multi-stage filtration and then mixed with an additive, and an electrolyte is obtained; s2, the electrolyte is subjected to heat exchange through a heat exchanger and then guided into an electrolytic bath, the temperature and the current density of the electrolyte are adjusted, and electrolytic foil generation is conducted; and S3, carrying out passivation and heat treatment on the copper foil obtained by electrolyzing the raw foil, and then trimming and rolling to obtain the ultrathin lithium battery copper foil, wherein the additive in the step S1 is a mixture of organic sulfide and an oxygen-containing polymer. The lithium battery copper foil prepared by the invention has good tensile strength and high elongation.

The invention discloses a system and a method for treating odor in a pretreatment stage of a municipal sewage plant. The method comprises the following steps: collecting gas; performing pretreatment; biological desulfurization: the pretreated odor enters a biological desulfurization tower from the bottom, hydrogen sulfide in the odor is oxidized into elemental sulfur or sulfate by acidophilic sulfur-oxidizing bacteria in the process of penetrating through an acidic biological filler layer, and meanwhile, part of ammonia and amine substances are removed through chemical absorption; alkali washing treatment: the gas subjected to biological desulfurization treatment enters an alkali washing tower from the bottom, and in the process of passing through an alkaline filler layer, residual hydrogen sulfide, ammonia gas, organic sulfide and the like are subjected to neutralization reaction with a sodium hydroxide solution so as to be removed; and up-to-standard discharge is realized. According to the invention, high-concentration hydrogen sulfide is efficiently and stably removed, and the impact of the high-concentration hydrogen sulfide on a subsequent treatment unit is avoided; various malodorous substances such as ammonia gas can be synchronously and efficiently removed; the impact load resistance of the system is improved, and the stability of the treatment effect is ensured; the medicament consumption and energy consumption are reduced, and the operation cost is reduced.

The invention provides a low-temperature absorption and adsorption coupling recovery treatment process for VOCs (volatile organic compounds) oil gas in a tank field, and relates to the technical field of VOCs treatment, which comprises the following steps: (1) low-temperature absorption: the VOCs oil gas in the tank field enters an absorption tower and is contacted with an intermediate material absorbent of a factory production device at-5-15 DEG C, and 80-90% of non-methane total hydrocarbon and organic sulfide are removed; (2) adsorption and removal: the absorbed oil gas enters an adsorption unit with three tanks connected in parallel, residual hydrocarbons are deeply removed through an adsorbent, and the hydrocarbon concentration of outlet tail gas is smaller than or equal to 60 mg / m; through the synergistic effect of low-temperature absorption and adsorption, various organic components in the VOCs oil gas in the tank field can be deeply captured, non-methane hydrocarbon can be efficiently removed, refractory components such as organic sulfide can be treated in a targeted manner, available resources in the oil gas are ensured to be fully recycled, and loss of valuable components is avoided.

The invention discloses a ternary lithium ion battery electrolyte and an application thereof. The ternary lithium ion battery electrolyte comprises a lithium salt, an ester solvent and an additive, the additives comprise an additive I and an additive II; the additive I is formed by introducing-CH3,-CH3O,-COOH,-CF3,-F and isomers thereof on a molecular structure of 1, 3-propane sultone. And the SEI film formed at the negative electrode contains more organic sulfides and fluorides, so that the interface impedance of the negative electrode is reduced, and Li < + > transmission at low temperature is facilitated. Meanwhile, more inorganic sulfides are formed in the CEI film on the positive electrode, so that the side reaction of an electrode / electrolyte interface at high temperature can be inhibited, and the high-temperature storage performance of the battery can be remarkably improved. And finally, the battery has relatively good high and low temperature performance.

The invention relates to an etching solution for regulating and controlling the etching speed of an embedded resistor copper foil and a preparation method of the etching solution. The etching solution comprises 4.6 wt%-16 wt% of HCl, 14.6 wt%-23 wt% of CuCl2 and 0.75 wt%-6.2 wt% of a mixture containing one or more of H2C2O4, KMnO4, H3PO4, organic sulfide and alcohols. According to the etching solution, the etching speed of the embedded resistor copper foil can be regulated and controlled, the problem that the WR-WC value is too large due to the fact that the etching speed difference of the etching solution on a copper layer and a resistance layer in the embedded resistor copper foil is large is solved to the maximum extent, lateral etching is reduced, the product quality is improved, and the production cost is reduced; and a smaller line width and a smaller line distance in the PCB are realized.

The present application relates to the technical field of metal organic framework materials, in particular to a modified copper-based metal organic framework material, a preparation method and application thereof, and a sulfide removal method. The modified copper-based metal organic framework material comprises a metal organic framework formed by copper and an organic ligand, and silver doped on the metal organic framework; and the crystal surface of the modified copper-based metal organic framework material has long and narrow honeycomb-shaped pores. + and Ag + The modified copper-based metal organic framework material has suitable pore structures and rich adsorption sites for removing various organic sulfides, and the modified copper-based metal organic framework material has Cu + and Ag + which can adsorb sulfides through π bond action, and has a large adsorption capacity and high adsorption selectivity for sulfides (such as mercaptans, sulfides, thiophenes, etc.) as a desulfurization adsorbent.

This application provides a desulfurization adsorbent comprising an oxide active component and a support, wherein the mass ratio of the oxide active component to the support is 1:(5~1000). The oxide active component is selected from one or more oxides of alkali metals, alkaline earth metals, and Group III subgroup metals. The support is selected from one or more molecular sieves of type A, type X, type Y, activated carbon, and porous metal fluorides. The desulfurization adsorbent described in this application exhibits good adsorption effect, large adsorption capacity, and long breakthrough time for various organic sulfides.

The present invention pertains to a conductive adhesive film (10) for joining a semiconductor device and a member, the conductive adhesive film (10) comprising: a stress relaxation layer (1) that is composed of a soft high-thermal-conductivity metal having a Young's modulus of 110 GPa or less at 25°C, a thermal conductivity of 100 W / m•K or more at 25°C, and a volume resistivity of 100 μΩ•cm or less; a first adhesive layer (2) that is provided on the side of the stress relaxation layer (1) to which the semiconductor device is joined, the first adhesive layer containing copper (Cu), tin (Sn), a bismaleimide resin, and an organic phosphine and / or an organic sulfide; and a second adhesive layer (3) that is provided on the side opposite the side of the stress relaxation layer (1) to which the semiconductor device is joined, the second adhesive layer containing copper (Cu), tin (Sn), a bismaleimide resin, and an organic phosphine and / or an organic sulfide.

The application provides a sulfate-reducing bacteria culture medium and application thereof, and components of the culture medium include: a carbon source, a nitrogen source, a phosphorus source, calcium chloride, magnesium chloride, an inorganic sulfur source, an organic sulfur compound with reducibility, inorganic trace elements, agar and water; wherein the mass content of the organic sulfur compound with reducibility is 5-30 mg / L, the mass content of the inorganic trace elements is 152-365 mg / L; the organic sulfur compound with reducibility includes lipoic acid and / or thiamine hydrochloride; and the inorganic trace elements include a combination of zinc elements, manganese elements, molybdenum elements and boron elements. The application introduces inorganic trace elements required by biological cell metabolism and rich sulfur electron acceptor species, promotes the growth and metabolism process of sulfate-reducing bacteria, and enables SRB cells to form visible colonies at a faster speed.

The invention belongs to the technical field of medicine preparation, and particularly relates to a synthesis method and an intermediate of rosmeltirol. The method comprises the following steps: (1) mixing SM1, organic monobasic acid and inorganic acid in proportion, stirring and dissolving, dropwise adding a sodium salt solution, and then adding SM2 and a carboxylate solution for reaction to prepare an intermediate 1; (2) dissolving the intermediate 1 in an amide compound, adding potassium salt, heating for reaction, and purifying to obtain an intermediate 2; (3) dissolving the intermediate 2 in aromatic hydrocarbon, adding boride, and performing deprotection and purification to obtain an intermediate 3; and (4) dissolving the intermediate 3 in an organic sulfide, then adding SM3 and inorganic salt, and carrying out heating reaction and purification to obtain the rosimeltirome. The method provided by the invention has the characteristics of concise, efficient and safe synthesis of the rosmeltirol, reduces by-products, is helpful for improving the purity and stability of the product, avoids the use of expensive Grignard reagent and complex purification steps, and is more suitable for large-scale industrial production.

The present invention pertains to a conductive adhesive film (10) for joining a semiconductor device and a member, said conductive adhesive film (10) comprising: a stress relief layer (1) configured from a perforated metal foil in which a through-hole is provided on the main surface of a metal foil formed of at least one metal selected from the group consisting of copper (Cu), a copper (Cu) alloy, aluminum (Al), and an aluminum (Al) alloy; a first adhesive layer (2) containing copper (Cu), tin (Sn), a bismaleimide resin, and an organic phosphine and / or an organic sulfide, sadi first adhesive layer (2) being provided on the side of the stress relief layer (1) to which the semiconductor device is joined; and a second adhesive layer (3) containing copper (Cu), tin (Sn), a bismaleimide resin, and an organic phosphine and / or an organic sulfide, said second adhesive layer (3) being provided on the side of the stress relief layer (1) facing the side to which the semiconductor device is joined.

The invention provides a feed gas desulfurization process for a synthetic ammonia device, relates to the technical field of synthetic ammonia, and solves the technical problem that a large amount of energy is wasted due to the fact that an existing hydrodesulfurization system is started after shutdown and temperature is raised in advance. The feed gas compressor is further provided with a heating gas path used for heating the desulfurization unit in advance, and the heating gas path is communicated with a first gas path used for introducing heating nitrogen and a second gas path used for recycling heating feed gas. The energy consumption is reduced, the heating efficiency is improved, and the driving time is shortened; the regeneration of an active phase in the regeneration process of the catalyst of the desulfurization unit can be ensured, organic sulfide is converted into inorganic sulfide (such as H2S) which is easy to remove, and the desulfurization efficiency is improved; the device is suitable for rapid temperature rising and heating during driving and is also suitable for raw material gas recovery during parking.

The present application relates to a kind of multi-stage pore composite mineral cat litter and its preparation method and recovery method, relate to cat litter technical field, to solve at least one of the problems such as insufficient adsorption amount of existing cat litter, poor catalytic decomposition ability to organic sulfide, environmental pollution, high cost, poor recycling ability etc..The present application realizes the targeted capture and efficient decomposition of multiple odor molecules in pet excrement by constructing gradient pore structure and biological-mineral composite deodorization system, and is suitable for feces management in scenes such as family pet care, stray animal rescue station and zoo.The specific cat litter core of the present application includes hierarchical porous diatomite, and modified sodium-based bentonite, to realize gradient adsorption and enrichment of odor molecules, and to promote the synergistic degradation of NH3, H2S and VOCs using a non-metallic catalytic-biological enzyme combined system.

The invention relates to a hierarchical porous composite mineral cat litter as well as a preparation method and a recovery method thereof, relates to the technical field of cat litters, and aims to solve at least one of the problems of insufficient adsorption capacity, poor catalytic decomposition capability on organic sulfides, environmental pollution, high cost, poor cyclic utilization capability and the like of the existing cat litter. By constructing a gradient hole structure and a biological-mineral composite deodorization system, targeted capture and efficient decomposition of multi-element peculiar smell molecules in pet excrement are achieved, and the pet excrement treatment device is suitable for excrement management in scenes such as family pet nursing, stray animal rescue stations and zoos. Specifically, the inner core of the cat litter comprises graded porous diatomite and synergistic modified sodium bentonite, gradient adsorption and enrichment of odor molecules are realized, and synergistic degradation of NH3, H2S and VOCs is promoted by adopting a non-metal catalysis-biological enzyme combined system.

The present invention belongs to the field of energy and chemical industry, and specifically discloses a method for selective oxidative desulfurization in petroleum and its products. In this method, in a polar phase composed of water and acetonitrile, organic sulfides in a non-polar phase oil solution are selectively removed by direct oxidation of peroxy organic acid and activation of the peroxy organic acid by a catalyst to produce active substances. In the polar phase, peroxypropionic acid is used as an oxidant, and low-valent transition metals are used as catalysts to activate the peroxypropionic acid to produce active substances to achieve oxidative removal of organic sulfur in the non-polar phase. This process is suitable for the direct removal of organic sulfur in petroleum and the selective removal of organic sulfur in petroleum products, and can be expanded to the selective desulfurization of various liquid phase systems, such as the desulfurization of waste tire pyrolysis liquid. This process is suitable for reactions under normal temperature and pressure, and the process flow is simple and can be flexibly adjusted according to actual needs.

The application discloses a vanadium ion flow battery with a praseodymium sulfide composite graphite felt electrode and belongs to the technical field of flow battery electrodes. The electrode comprises a graphite felt base body and a surface-loaded praseodymium sulfide composite layer, the composite layer is composed of praseodymium sulfide nanoparticles and carbon nanomaterials, and the particle size of the nanoparticles is 5-50 nm. Preparation is carried out by mixing a praseodymium source and a sulfur source to prepare a precursor, mixing the precursor with a carbon nanomaterial dispersion liquid, performing graphite felt thermal oxidation pretreatment, hydrothermal reaction, washing and drying, and inert atmosphere heat treatment. In the application, inorganic rare earth praseodymium sulfide is used to replace organic sulfide and nitrogen-doped carbon material, Pr 3+ / Pr 4+ is used to realize efficient catalysis, the electrode is resistant to strong acid, stable in a wide temperature range, firmly combined at an interface, and long in cycle life. The electrode can be used in all-vanadium, zinc-bromine, iron-chromium and other flow batteries, is also applicable to the fields of hydrogen production by electrolysis, supercapacitors and electrocatalysis, and is mild in process and easy to scale up.

The invention relates to a method for efficiently and synergistically purifying multiple metals in wet-process phosphoric acid, which comprises the following steps: (1) adding an inorganic sulfide accounting for 0.05-0.40% of the mass of wet-process phosphoric acid slurry into the wet-process phosphoric acid slurry, and reacting for 30-60 minutes at the temperature of 80-85 DEG C and the stirring speed of 100-200 r / min; (2) pumping the reacted slurry into a filter, adding an organic sulfide accounting for 0.05-0.20% of the mass of the wet-process phosphoric acid slurry at the front end of a pump, and reacting for 10-90 seconds under the conditions that the temperature is 70-80 DEG C and the rotating speed of the pump is 900-1500 r / min; and (3) filtering to obtain dilute phosphoric acid, and aging, concentrating and aging the dilute phosphoric acid to obtain the finished product concentrated phosphoric acid. The sulfide and dithiophosphate synergistic process is adopted, the reaction time with organic sulfide is shortened to the second level, the defect that in the prior art, the efficiency of a single cadmium removal agent is low is overcome, multi-metal ions such as arsenic, cadmium and copper are synchronously removed, the removal rate reaches up to 98% or above, and the cadmium removal treatment cost of per ton of phosphoric acid is greatly reduced.

The utility model discloses a dry gas removes organic sulfur system. The dry gas removes organic sulfur system includes: low temperature absorption tower, with the dry gas and low temperature absorption oil of hydrogen sulfide removal as feed, in which dry gas and low temperature absorption oil counter current contact, and get rich absorption oil and absorption tail gas after absorption, hydrolytic reactor, with absorption tail gas as feed, in which the carbonyl sulfur in absorption tail gas is hydrolyzed, amine liquid absorption tower, with hydrolytic tail gas and lean amine liquid as feed, and hydrogen sulfide in hydrolytic tail gas is removed by absorption, and gets rich amine liquid and purifying dry gas. The utility model can purify and remove the organic sulfide in dry gas, reduce the organic sulfur content in gas, and then reduce the SO2 content in the flue gas of the heating furnace of each device.

The present invention relates to a conductive adhesive film (10) for joining a semiconductor device and a member, the conductive adhesive film comprising: a stress relaxation layer (1) composed of a soft, highly thermally conductive metal having a 0.2%-proof stress at 25°C of 200 N / mm2 or less, a thermal conductivity at 25°C of 50 W / m·K or more, and a volume resistivity of 100 μΩ·cm or less; a first adhesive layer (2) that includes copper (Cu), tin (Sn), a bismaleimide resin, and an organic phosphine and / or an organic sulfide, and that is provided on the side, of the stress relaxation layer (1), to which the semiconductor device is joined; and a second adhesive layer (3) that includes copper (Cu), tin (Sn), a bismaleimide resin, and an organic phosphine and / or an organic sulfide, and that is provided on the side, of the stress relaxation layer (1), opposite to the side to which the semiconductor device is joined.

Disclosed in the present invention are a metal-doped alumina supported basic catalyst, and a preparation method therefor and a use thereof. The catalyst comprises a support and a basic component supported on the support. The support comprises Al2O3, AgxOy and RemOn. By regulating one or more of the following parameters or conditions: the content and / or valence state of AgxOy and RemOn in the support, and the synergistic effect thereof with Al2O3 in the support, the supported basic component, and an optional modified component, the performance of the catalyst is significantly improved, so that the catalyst has better desulfurization efficiency and operation period, and can achieve adsorption removal and refining of different organic and inorganic sulfides under low temperature conditions. Moreover, the catalyst can be regenerated repeatedly, and the preparation method therefor is simple and easy to implement, and is suitable for industrial production.

Disclosed is a process for treating a residual stream from bisphenol production, wherein the residual stream includes unreacted phenols, bisphenol isomers, triphenols, organic sulfides, and water. The process comprises contacting at least a portion of the residual stream or reaction products thereof with an acidic catalyst under conditions sufficient to allow acid-catalyzed hydrolysis of organic sulfides within the residual stream to the corresponding mercaptans and produce an effluent stream; and then distilling at least a portion of the effluent stream to recover a distillate product comprising phenols and mercaptans and produce a bottoms product comprising bisphenol isomers and triphenols and having a lower organic sulfide content than the residual stream.