Abstract: A pellet formed from a mix of two polymer materials which are non-homogenous is extruded through a die to form a highly roughened surface creating an enhanced melt fracture appearance. The extrusion is chopped into pellet form to provide a large surface area pellet to be used as a harbour for biomass in water treatment processes. Large quantities of such pellets in a filter provide a very effective filtration effect, largely because the highly roughened surface provides an enormous number of cavities within which the biomass can be retained.

Abstract: Granulocytes can be removed from blood by bringing the blood into contact with a carrier having higher affinity to granulocytes than to lymphocytes. the carrier may preferably be a substance having a contact angle in a range of 55.degree.-95.degree. to water, e.g., polystyrene, cellulose acetate, nylon, polytrifluoroethylene or polyethylene terephthalate. A granulocyte removing apparatus is also disclosed. It comprises a granulocyte-adsorbing portion enclosing therein a carrier having higher affinity to granulocytes than to lymphocytes, a blood inflow port for causing blood to flow into the adsorbing portion, and a blood outflow port for allowing the blood, which has flowed in the adsorbing portion, to flow out of the adsorbing portion.

Abstract: A hollow fiber contactor and process for fluid treatment having forced circulation with entry of fluid to be treated through the open ended lumen of a porous input hollow fiber having its opposite end closed and exit of treated fluid through the open ended lumen of an adjacent or nearby porous output hollow fiber having its opposite end closed. Fluid to be treated passes through the porous wall of an input hollow fiber, passes in contact with a treatment medium between the input and output hollow fibers forming treated fluid which passes through the porous wall of an output hollow fiber and exits the process. This invention provides high contact with treatment medium between the hollow fibers, especially suitable for selective sorption for gas purification or separation and for conduct of catalytic reactions.

Abstract: A universal water filter for filtering water poured into an opening of the container. The water filter includes a filter unit and a support structure. The filter unit includes a housing having an inlet surface for receiving unfiltered water, an outlet surface for dispensing filtered water and a side surface between the inlet surface and the outlet surface. The support structure extends from the sidewall of the housing for supporting the water filter across the opening of the container. The support structure is adjustable along the circumference of the housing to vary the position of the support structure with respect to the size and shape of the opening of the container.

Abstract: An object of the present invention is to carry out the extraction and purification of DNA in a short period of time. This object is accomplished by DNA extraction and purification apparatus illustrated in the drawing. This apparatus includes a pipetting unit which can be horizontally moved along a rail by means of a transfer device. This apparatus also includes tube racks which can be moved horizontally and vertically. In these tube racks are disposed filter tubes (not shown) for the extraction and purification of DNA. Moreover, a waste liquid vat and a recovery vat are disposed below these tube racks. The waste liquid vat and the recovery vat are each provided with a suction port (not shown) to be connected to a vacuum pump.

Abstract: The process for producing the albumin preparation of the present invention comprises treating an aqueous albumin solution with an anion exchanger and a cation exchanger and subjecting the solution to heat treatment wherein a polyacrylamide type carrier having a cation exchange group is used as a cation exchanger. By using a polyacrylamide type carrier as a cation exchanger, the polymerization caused by the contaminating proteins can be suppressed, and a highly purified albumin preparation can be obtained.

Abstract: The invention is a gel comprising water, sodium ions, calcium ions, and about 0.3 and 4% alginate, wherein the ratio of sodium ions to calcium ions is between about 15:1 to about 45:1. In a preferred embodiment of the invention, the alginate comprises mannuronic acid and guluronic acid in a weight ratio of between about 2:1 and 0.35:1.

Abstract: Undesirable ionic species are removed from water by way of a passive treatment employing apparatus in the form of a porous container which confines a multitude of pieces of sponge containing a chelation polymer. The container, preferably of tubular shape and having a draw-string closure, is emplaced into a region through which water to be treated is caused to flow. The manner of emplacement is such as to prevent by-pass of water around the container. After a suitable time interval, the apparatus is removed and replaced with similar apparatus having fresh sponge.

Abstract: An apparatus for extracting an analyte from a liquid sample, comprises a microcolumn having a microparticulate media therein, the media being sandwiched between two compression layers. Preferably, the compression layers comprise a binder-free glass fiber, held in the microcolumn by upper and lower polypropylene mesh.

Abstract: Disposable paper filters suitable for removal of contaminants from fluids such as water or air are disclosed. Specific embodiments include single-ply and multi-ply filters in which metal removal additives and/or halogen and organic contaminant removal additives have been distributed during the manufacturing process. Special manufacturing methods for producing such composite filters are also described.

Abstract: Acids contaminated with multi-valent metal salts are purified by a process which involves treatment in an acid sorption unit (ASU) and a nanofiltration unit (NFU). The feed solution can first be delivered to the ASU, which produces two solutions, one high in acid concentration and the other high in metal salt concentration. The high acid concentration solution can be treated in the NFU to produce an acid end product and a reject metal salt solution which can be recirculated to the feed of the NFU. Alternatively, the high metal salt solution can be treated in the NFU, and its permeate recirculated to the ASU as eluate. In an alternative configuration, the feed is delivered first to the NFU. In all cases, the membrane reject solution from the NFU is recirculated to increase the metal salt concentration. A second NFU can be used to process the solution from the ASU which contains a high metal salt concentration.

Abstract: A TOC monitor for determining the quality of ultrapure water is described. The TOC monitor includes a ultraviolet oxidizer in the form of spiral tubing, having an inlet connected to a first resistivity meter and an outlet to a second resistivity meter. The difference between the measured resistivity values provides an indication of the total amount of organic carbons present in the water. Each resistivity meter includes an outer tubular electrode and an inner cylindrical electrode extending therethrough. A narrow annular space is formed therebetween for increased flow of the water, permitting an accurate measurement even at very low flow rates. Such TOC monitors are used in a ultrapure water production plant to continuously monitor the quality of water. The plant can produce ultrapure water in a continuous process and accordingly dispense with costly and contaminants producing reservoirs.

Abstract: A microfibrous sorbent article is provided. The microfibrous sorbent article comprises an elongate boom having a substantially oval cross-section. The boom is formed of multiple adjacent microfibers layers, the layers being bonded to each other by entanglement of fibers between adjacent layers. The boom further contains ion exchange resin, selectively absorbent particulate material, catalytic agent or selectively reactive particulate material.

Abstract: A new and improved self-contained, portable, treated drinking water, refrigerator storage jug assembly is provided. The jug assembly includes a storage jug configured to be placed in a refrigerator. A water treating subassembly is mounted to the back of the storage jug and is placed in the refrigerator together with the jug. A fluid connector for connecting the portable jug and water treating subassembly to a kitchen sink for refilling is provided. In a preferred embodiment, the water treating subassembly includes a plurality of water treating modules interconnected to each other. Also in the preferred embodiment, a modular, leak-free flow block connector and a treatment module monitoring device form a part of the overall jug apparatus.

Abstract: A tertiary treatment unit is provided that has a first filtration unit operatively connected to an influent for filtering solids therefrom to form an effluent, a second filtration unit operatively connected to the first filtration unit to receive the effluent and to filter finer solids and bacteria and viruses from the effluent, a supply tank operatively connected to the effluent to provide chemicals that are mixed into the effluent, and a reactor that receives the effluent and removes nitrogen and some phosphorous therefrom to form a treated effluent. The treatment unit further has a first adsorption unit that receives the treated effluent and adsorbs additional nitrogen, BOD, TSS and certain chemicals from the treated effluent, and a second adsorption unit that receives the partially adsorbed treated effluent from the first adsorption unit and adsorbs additional phosphorous from the treated effluent to form the final effluent.

Abstract: Purification of aqueous hydrogen peroxide solutions using conventional ion-exchange techniques can result in the hydrogen peroxide decomposing explosively. Much safer processes are obtained by restricting the contact between the resin bed and the hydrogen peroxide solution to a very short contact time, by employing a treatment chamber that is vented to the atmosphere and also by slurrying the resin bed. The bed is conveniently retained on a mesh that acts as a filter (13) preferably conical having an aperture (17) at its apex through which is introduced a small fraction of the solution countercurrent (10) to the main solution flow (9) in order to slurry the bed (19). The solution can be recycled through the same bed or a plurality of beds. Very high purification can be achieved and combined with improved safety of operation.

Abstract: A method system for treating water in which the incoming effluent water is pre-filtered, passed through a reverse osmosis unit, post filtered to remove taste and odor and then passed to a holding tank. The holding tank is provided with a source of ultraviolet light to provide disinfection in the holding tank to eliminate bacterial growth prior to consumption of the water therein.

Abstract: A method of depth filtration of particles from a fluid carrying particles including providing in a deep filter a quantity of filter medium elements, at least some of the elements being ionically conductive, applying an electric field to the deep filter to cooperate with individual the elements, permitting or causing said fluid with particles to flow into the deep filter, influencing the movement of particles in the deep filter by the electric field to enhance the filtration of the particles from the fluid. Suitable elements are polyacrylic fibers treated with caustic soda to modify the surface charge, where the electrical conductivity of the fibers vary within individual fibers and between different fibers. The application also concerns an apparatus where the filter medium is supported by a plastic mesh. Disc electrodes permit drinking water to be purified.

Abstract: Carbon-clad zirconium oxide particles are disclosed which are useful in sorbent applications, particularly as packing materials for High Performance Liquid Chromatography (HPLC). A method for the preparation of chromatographic support material is also disclosed which utilizes low pressure.

Abstract: The process for isolating albumin from supernatant IV, and in particular IV-4, or from COHN's fraction V or from a plasma supernatant or fraction of analogous composition derived from an alcoholic or nonalcoholic fractionation, comprises one step on a hydrophilic anion exchange column with binding of albumin to the column, and then elution, and one step on a hydrophobic anion exchange column. Albumin thus obtained having a purity >99% by cellulose acetate electrophoresis, being free from impurities detected by crossed immunoelectrophoresis and free from polymers.

Abstract: In the preparation of poly(m-phenylene isophthalamide) filaments, hydrogen chloride is removed from as-produced amide solution of poly(m-phenylene isophthalamide) by contact with basic ion exchange resin.

Abstract: Storm water runoff is treated by passing the runoff through a bed of high quality leaf compost material to remove pollutants from the runoff prior to discharge into a water receiving system, such as a river, lake or storm water drainage system. Apparatus for treating storm water runoff is disclosed having at least one chamber for containing compost defined by a pair of opposed side walls and a pair of opposed end walls; an influent pathway for providing storm water to the compost chamber, a drain field positioned beneath the compost chamber for receiving storm water from the compost chamber, a layer of water permeable material interposed between the compost chamber and the drain field providing fluid communication between the compost chamber and the drain field while preventing the flow of compost material into the drain field, and a storm water outlet in fluid communication with the drain field for discharging treated storm water from the apparatus.

Abstract: This invention concerns a method and apparatus for collecting and preserving field water samples on site in which a salt solution, contained in a syringe by a rupturable thin film membrane, is injected through a strong acid or base ion exchange filter to produce a required amount of either nitric acid, sulfuric acid or sodium hydroxide for sample collection and preservation.

Abstract: A separation medium for use in protein separation comprising a water-insoluble matrix carrying a plurality of polyamine groupings, the polyamine groupings having at least three basic nitrogen atoms, the basic nitrogen atoms being separated from each other by a chain of at least two intervening carbon atoms, there being a total of 5 such intervening carbon atoms when there is a total of three nitrogen atoms in each polyamine group, which may be used for at least partially purifying factor VIII.

Abstract: A new and improved self-contained, portable, treated drinking water, refrigerator storage jug assembly is provided. The jug assembly includes a storage jug configured to be placed in a refrigerator. A water treating subassembly is mounted to the back of the storage jug and is placed in the refrigerator together with the jug. A fluid connector for connecting the portable jug and water treating subassembly to a kitchen sink for refilling is provided. In a preferred embodiment, the water treating subassembly includes a plurality of water treating modules interconnected to each other. Also in the preferred embodiment, a modular, leak-free flow block connector and a treatment module monitoring device form a part of the overall jug apparatus.

Abstract: A process for the processing or upgrading of heavy oil fractions containing polynuclear aromatics is disclosed. The process comprises selectively oxidizing a feedstock under low severity conditions in a multi-phase system, wherein one phase is an aqueous and contains water-soluble catalyst, deoxygenating that product followed by hydroprocessing to yield a substantially mononuclear product.

Abstract: Systems are described for removing organic solvents such as kerosene-based solvents, from aqueous solutions, in leaching processes for recovering metal such as copper from ore. A unit for recovering small amounts of kerosene-based solvent from raffinate (which comprises acidic water with a small amount of solvent and debris) includes both a plate-type coalescing device (60, FIG. 2 ) and a granular bed (62) in series, and preferably located in the same vessel (54). The raffinate first moves through the plate-type coalescing device where much of the kerosene is removed, to greatly increase the useful period of the granular bed (before it has to be backwashed). In a unit (20, FIG.

Abstract: Polymer-coated carbon-clad inorganic oxide particles are disclosed which are useful in sorbent applications, particularly as packing materials for High Performance Liquid Chromatography (HPLC). A method for the preparation of a chromatographic support material is also disclosed which comprises coating carbon-clad inorganic oxide particles with a monomer or oligomer and cross-linking the monomer or oligomer.

Abstract: An apparatus and method for substantially eliminating diffusion and resin capacity as rate-limiting factors in mass transfer between phases in separation, chemical reaction, and biological culture processes by establishing turbulent flow of fluids within a continuous, moving belt of resilient, open-cell foam polymer. The belt is made to move alternately between bulk liquid and gas phases where mass transfer takes place by direct transport to the polymer surface as a consequence of compression and release of the belt.

Abstract: A device and a related method are provided for reclaiming or recovering dry cleaning solvent from otherwise disposable fluid contained within a separator or other suitable receptacle of a dry cleaning machine. The device includes an evaporator and a fluid transfer mechanism for transporting fluid evaporated by the evaporator through a filter that removes substantially all of the solvent present within the evaporated fluid. Alternatively, a filter can be interposed between the separator or other suitable receptacle and the evaporator so that solvent is filtered before reaching the evaporator. Consequently, the device substantially reclaims or recovers dry cleaning solvent that may still be present within the fluid that is to be otherwise disposed of from the separator or other suitable receptacle.

Abstract: A molecular sieve material is combined with a porous carrier material. The pores of the molecular sieve material are impermeable to molecules or organisms having a size equal to or greater than that of the water molecule either because the molecular sieve material is selected so as to have pores which are smaller than such molecule or because the pores of the molecular sieve material are closed by a film. The pores of the molecular sieve material thus remain unoccupied and are able to exert an attractive force on molecules or organisms which are to be captured. The pores of the carrier material are designed to accept molecules or organisms having a size equal to or greater than that of the water molecule so that, when such molecules or organisms are attracted by the molecular sieve material, they can be trapped in the carrier material.

Abstract: An enzyme-fixed bioreactor, including a reaction column, enzyme-fixed catalyst particles uniformly and densely filled in the reaction column, the catalyst particles being composed of carrier sepiolite particles consisting essentially of sepiolite and an enzyme carried on the surface of the carrier sepiolite particles. The bioreactor has stable heat resistant and chemical properties, high productivity, and is economically superior to prior art, without fear of destruction of the catalyst, short path, and clogging in the reaction column.

Abstract: A process and apparatus is provided for collecting a patient's blood for re-use of autotransfusion, in which blood is collected from a patient and delivered for treatment in a container, outside the patient, for later re-use or retransfusion to the patient. The treatment given to the blood before autotransfusion may reside in treating the blood to resist coagulation, treating the blood for removal of fats from the blood, or in removing other substances from the blood. The treatment, insofar as it is used to cause the blood to resist coagulation, includes withdrawing calcium ions from the blood and replacing them with other ions in sufficiently small quantities that the amount of other substance that is added to the blood is not harmful, preferably by passing the blood through a bed of ion exchange polymeric resin material. Insofar as fats are moved from the blood, the treatment includes collecting blood from the patient and wicking fats from the blood by means of a hydrophobic lipophilic wick.

Abstract: The filtration system provides a long horizontal flow path through buoyant filter media. The filter media is contained in a vessel and the relationship between the water level in the vessel and the amount of filter media is such that the media extends completely across the horizontal flow path of the water during the filtration mode of operation. The system is configured so that the buoyant media volume expands during a cleansing mode of operation.

Abstract: A filter device for filtering hydrocarbon fuel, such as gasoline, includes a filter device having a ceramic material which can activate water. The hydrocarbon fuel which is passed through the ceramic material can be activated by the ceramic material. The ceramic material may comprise ceramic particles housed in the filter body, or a powdery ceramic material attached to the filter body, which comprises an elastic network body having interconnected spaces communicating with each other.

Abstract: The Strainer has a pipe with a multiplicity of holes, and surrounded by a mass of stones or marbles, confined within a double nylon netting. The pipe confines a one-way check valve. The mass of stones or marbles serves a dual purpose: weighting of the Strainer, and ancillary filtering of the fluid. The stones or marbles are of approximately three-quarters of an inch in diameter and, consequently, they have a multitudinous number of interstices which are not less than three-sixteenth of an inch in width, length and depth. These present virtually unlimited pathways, of gross dimensions, for the extraction of water.

Abstract: Magnetically stabilized fluidized bed technology is utilized in conjunction with ion-exchange adsorption/desorption processes in a method and system for isolating proteins from cell lysate. The invention also includes a magnetizable, porous, ion-exchange particle, and a method for producing the same, for use with the stationary magnetically stabilized fluidized bed protein isolation process.

Abstract: An apparatus for producing a black matrix-type phosphor screen of a cathode ray tube is disclosed, which includes a carbon coating nozzle for coating a carbon slurry on a cathode ray tube panel, a tank for containing the carbon slurry, a supplying system for supplying the carbon slurry from the carbon slurry tank into the carbon coating nozzle and a collecting system for collecting excess carbon slurry produced from the carbon coating nozzle back into the carbon slurry tank, and a carbon slurry regenerating device using an ion-exchange resin is provided. The regenerating device can be placed in at least one of the supplying system, the collecting system and the carbon slurry tank.

Abstract: The improved method and apparatus are capable of efficient removal of radioactive europium from solutions of radioactive gadolinium in a simple way. A mixture of a zinc and a graphite powder is packed into a column and both a conditioning solution corresponding to a liquid electrolyte and a sample solution containing radioactive gadolinium and europium are allowed to pass through the column.

Abstract: Patients suffering from HIV-1 infection, including both those who have and those who have not developed acquired immunodeficiency syndrome, are treated by extracorporeal removal of IgG and immune complexes. An immunoadsorbent material for removing IgG and IgG-complexes from biological fluids is prepared by covalently binding protein A to a solid-phase silica matrix. It has been found that particularly stable, high-capacity immunoadsorbents are obtained by derivatizing the silica with amino and/or carboxyl groups, and reacting the protein A with a carbodiimide at a pH in a range from 3.5 to 4.5. Binding through free hydroxyl groups may be achieved with cyanogen halides at a pH in the range from 11.0 to 11.5. After acid washing (pH 2.0-2.5) to remove non-covalently bound protein A, the immunoadsorbent may be employed in a column for therapeutic treatment of various cancers and autoimmune disorders where IgG-complexes are implicated as suppressing factors in inhibiting a normal immune response.

Abstract: A method and apparatus for producing activated mineral water. Material water is pressurized by a pump and passed through a plurality of columns connected in series and filled with inorganic substances, so that the pressurized water is brought into contact with the inorganic substances while passing through the pipes. The water discharged from the pipes is aerated. The abovementioned cycle may be repeated a plurality of times.

Abstract: Highly concentrated and toxic petroleum-based and synthetic fuels wastewaters such as oil shale retort water are treated in a unit treatment process by electrolysis in a reactor containing oleophilic, ionized, open-celled polyurethane foams and subjected to mixing and lBACKGROUND OF THE INVENTIONThe invention described herein arose in the course of, or under, Contract No. DE-AC03-76SF00098 between the U.S. Department of Energy and the University of California.

Abstract: An arrangement for collecting blood from a source of blood employs a filter chamber having a substantially predefined volume for accumulating the collected blood, and first and second access ports for receiving the collected blood and for venting the filter chamber, respectively. A protamine filter is arranged within the filter chamber, and preferably is formed of regenerated cellulose hollow fibers which have been activated with CNBr and have protamine immobilized thereon. The amount of protamine immobilized thereon is controlled in a variety of ways, prior to installation and sealing of the filter element within the filter chamber. In a practical embodiment, the first port of the filter chamber is coupled to a conventional cannula needle for communicating transdermally with a living being or through a membrane of a blood storage container. The second port is coupled to a conventional syringe which applies a suction for facilitating withdrawal of the blood.

Abstract: A purification system for cooling tower water where no antiscalent chemicals need be added when the water is provided from a municipal source. The water is continually filtered and disinfected, and its TDS is kept at acceptable levels, by the use of nanofiltration in combination with ionization. Water discharge form the tower is reduced by 80 percent or more.

Abstract: A corrosion product monitoring system and method are described using a recirculation loop including a sample line, a particulate collection vessel, a recirculating pump, a microporous membrane "cross-flow" filter, and valves to control the flow rate and pressure of a fluid sample taken from the secondary fluid system of a nuclear power plant. The liquid sample is processed at a constant flow rate and temperature. When a relatively short time has elapsed in a trial sample run to stabilize conditions in the sample line, an actual sample run is started by feeding sample into the loop. Non-soluble, particulate concentration increases in the filter and particulate collection vessel as the run progresses. The permeate of soluble contaminants is passed through an ion exchange column to concentrate soluble ions in the sample. The filter is backwashed on a timed cycle by filtered water pressurized by a pump, or gas pressure, by realigning the system valves.

Abstract: A method of removing heavy metals from aqueous solution, a composition of matter used in effecting said removal, and apparatus used in effecting said removal. One or more of the polypeptides, poly (.gamma.-glutamylcysteinyl)glycines, is immobilized on an inert material in particulate form. Upon contact with an aqueous solution containing heavy metals, the polypeptides sequester the metals, removing them from the solution. There is selectivity of poly (.gamma.-glutamylcysteinyl)glycines having a particular number of monomer repeat unit for particular metals. The polypeptides are easily regenerated by contact with a small amount of an organic acid, so that they can be used again to remove heayv metals from solution. This also results in the removal of the metals from the column in a concentrated form.

Abstract: To sterilize and purify continuously water in a water tank, a water treating apparatus is provided that comprises a circulating type water pipe for taking the water in the water tank outside the water tank and then for returning the water into the water tank, and an ozone supply apparatus, a filtering apparatus, and an ultraviolet-light irradiating apparatus that are situated in the course of the water pipe, so that water can be sterilized and purified thoroughly by a three-stage treatment incluing "an ozone treatment" wherein the decomposition of organic substances, deodorization and inactivation of microorganisms by ozone can be expected, "a filtering treatment" wherein the elimination of foreign matters and microorganisms can be expected, "an ultraviolet treatment" wherein the sterilization by ultraviolet rays can be expected.

Abstract: A sorption vessel including a tank for retaining a pulp of an aqueous slurry and a sorbent at a predetermined liquid pulp level therein; and an interstage screening system disposed within the tank and at least partially submerged beneath the predetermined pulp level. The interstage screening system includes a housing for isolating the system from the pulp, thereby providing a hydraulic differential between the predetermined pulp level and the screening system; a conduit for selectively introducing the pulp onto the screen member, the pulp being urged through the conduit by the hydraulic differential; and at least one screen member disposed within the housing for selectively and continuously separating the sorbent from the pulp.

Abstract: This invention relates to a method for improving the performance of liquid embrane separations by coating a liquid membrane onto solid ion-exchange resin beads in a fixed bed. Ion-exchange beads fabricated from an ion-exchange resin are swelled with water and are coated with a liquid membrane material that forms a film over the beads. The beads constitute a fixed bed ion-exchange column. Fluid being treated that contains the desired ion to be trapped by the ion-exchange particle is passed through the column. A carrier molecule, contained in the liquid membrane ion-exchange material, is selected for the desired ion in the fluid. The carrier molecule forms a complex with the desired ion, transporting it through the membrane and thus separating it from the other ions. The solution is fed continuously until breakthrough occurs at which time the ion is recovered, and the bed is regenerated.

Abstract: A method and apparatus for uniformly distributing fluid across the entire cross section of a reaction medium and for compensating for volumetric changes in the reaction medium utilized a resilient membrane which cooperates with an adjacent fluid manifold distribution chamber. The combined operation of the manifold distribution chamber with the resilient membrane provides a low resistance to fluid flow in a direction transverse to fluid flow through the reaction medium and a higher resistance to fluid flow across the membrane in the direction of fluid flow through the reaction medium. In this way, fluid is evenly distributed across the cross section of the reaction medium prior to entering the reaction medium and after leaving the reaction medium. The resilient membranes have reserve expansion capabilities, when hydrated, to accommodate expansion in the reaction medium. The resilient membranes are also sufficiently resilient to accommodate expansion of the reaction medium when necessary.