Abstract: This invention presents novel membrane laminate structures useful for osmotic distillation, and methods for their preparation.

Abstract: A method of brewing coffee having reduced acidity is described. In the method, an acid-neutralizing composition comprising calcium carbonate, potassium hydroxide, magnesium hydroxide, and potassium chloride is utilized to produce a brewed coffee having a pH of from about 5.7 to about 6.1. A coffee product including ground coffee and an acid-neutralizing composition is also described.

Abstract: The present invention concerns the use of an adsorbent material modified with polynuclear metal oxyhydroxides for the selective elimination of inorganic phosphate from liquids, in particular from body fluids containing protein such as whole blood, plasma, liquid contents of the intestine as well as from dialysis fluid, as well as a process for the production of a pharmaceutical agent for oral application for the selective removal of inorganic phosphate in which an adsorbent material used according to the present invention, as such or pressed into powder form, is coated with a layer resistant to gastric acid or dispensed into an acid-resistant capsule. In order to selectively eliminate inorganic phosphate in an extracorporeal perfusion system, a body fluid such as whole blood or plasma is passed over one of the adsorbent materials.

Abstract: Structures comprising an upper crystalline molecular sieve layer on a support, the crystals being at least partially oriented normal to the plane of the layer, there being a dense intermediate crystalline molecular sieve layer between the support and upper layer.

Abstract: A process for the preparation of semipermeable membranes with improved acid and base stability including: (a) coating a base and acid stable ultrafiltration (UF) membrane support polymer, with a high molecular weight amphoteric polyelectrolyte coating polymer optionally in solution, the amphoteric polyelectrolyte containing both cationic and anionic groups and in addition primary and secondary amine groups, the solution optionally containing a latent internal crosslinker compound that is a polyfunctional compound that crosslinks the coating polymer only during a curing step at elevated temperatures and basic pH; (b) draining or washing the coated support; and (c) reacting the coating with a solution of an external crosslinking compound that is a polyfuntional compound, not overly reactive so as not to be hydrolyzed prematurely in solution, the time of exposure to the external crosslinking compound being sufficient to ensure its diffusion into the bulk of the coating, so that the crosslinking is effected not o

Abstract: Shaped articles which are suitable as biocidal depth-type filters and consist of fibrous materials and particles, embedded therein, of crosslinked crospovidone-iodine or crospovidone-hydrogen peroxide.

Abstract: A fluid filter includes a first batting of high loft, non-woven, fibrous fluid-permeable material with a plurality of openings formed through the thickness thereof across the length and width of the batting. A second layer of high loft, non-woven, fluid-permeable fibrous batting is attached to the first layer and extends across the entire length and width of the first layer. Preferably, the first and second layers are adhered together to form a single integral fluid filter. In the preferred form of the invention, the openings in the first batting have side walls which are perpendicular to the upper surface of the batting, such that fluid flow impacts on the upper surface of the batting, rather than directly impacting on the side walls.

Abstract: A leukocyte-removing filter material is described, which includes a porous element having fine pores of an average pore diameter of not less than 1.0 .mu.m but less than 100 .mu.m and a fiber structure composed of a plurality of fibers having an average fiber diameter of not less than 0.01 .mu.m but less than 1.0 .mu.m kept on the porous element. The porosity of the filter material is not less than 50% but less than 95%, and the proportion of the fiber structure to the filter material is not less than 0.01% by weight but less than 30% by weight. The ratio between the average pore diameter of the porous element and the average fiber diameter of the fiber structure is not less than 2 but less than 2,000 and the above fiber structure forms a reticulate structure. A process for producing the leukocyte-removing fiber material and an apparatus for removing leukocyte using the above fiber material are also described.

Abstract: Novel blood cell fractionation devices are provided. The device utilizes filters coated with high molecular weight polyethylene oxide derivatives cross-linked to prevent leaching from filter surfaces. These filters have a special efficacy in preventing protein adsorption and cellular adhesion to the membrane filter.

Abstract: Weathered reef-building coral is immersed in an aqueous alkali solution under reduced pressure to carry out alkali washing to make the aqueous alkali solution penetrate into the weathered reef-building coral throughout its fine structure inside the porous tissue, which is subsequently washed with water until a washing from the inside of the porous tissue is neutralized.As a result of this washing, various marine algae, various microorganisms including Vibrio bacteria inhabiting the ocean and other various organic substances held in the inner fine structure of weathered reef-building coral can be removed. Thus, a weathered reef-building coral material can be obtained whose safety has been ensured. This weathered reef-building coral material is suitable for food materials, filter mediums for water purifiers and so forth.

Abstract: A method of making a solid filter material which filters a predetermined wavelength band from a broader spectrum of radiation is provided. The method includes creating a colloidal structure composed of particles dispersed within a medium, and introducing a solvent thereto. Thereafter, the solvent is evaporated and the remaining structure solidifies into a solid crystalline array. The particles can also be fused together by polymerization using one of several methods which are provided. In another embodiment, methods of filtering submicron particles have been developed which consists of establishing a gel membrane from a crystalline colloidal array with an interstice size less than or equal to the particles to be filtered are disclosed. The gel membrane may employ anisotropic interstices of submicron size and is stretchable or compressible mechanically.

Abstract: This invention relates to a plasma-collecting device which comprises a blood filtering material comprising glass fiber filter and microporous membrane, a holder having a blood inlet and a plasma outlet accommodating the blood filtering material, a blood-collecting needle being connected to the blood inlet, and a plasma receiver being provided on the plasma outlet side. The plasma-collecting device can collect a necessary amount of plasma for analysis from blood vessel directly, easily and surely.

Abstract: A composite filter media includes a fibrous filtration layer of randomly oriented fibers and one or more pleatable stiffening layers which enable the composite filter media to be pleated and hold or retain its pleats. The pleatable stiffening layer(s) may enhance the dirt holding capacity of the composite filter media especially when positioned upstream of the fibrous filtration layer. The composite filter media may also include a flexible covering layer which functions to block the loss of fibers from the fibrous filtration layer. Preferably, the mean fiber diameter of the fibers in fibrous filtration layer increases and the density of the fibrous filtration layer decreases throughout the thickness of the fibrous filtration layer from one major surface to the other major surface of the fibrous filtration layer.

Abstract: A ceramic filter containing at least one functional material and method of manufacturing, a ceramic filter whose surface through which a liquid to be purified flows into is densest and the average particle size of the filter continuously increases toward the interior thereof, a method of manufacturing the ceramic filter including ultrasonic vibration, an extrusion molding die used to manufacture the ceramic filter and an extrusion molding apparatus using the die.

Abstract: The subject matter of the present invention is a device for purifying lightly laden water containing particles and/or fatty matter and/or microorganisms in suspension. The device of the invention is a filter comprising a grid (1) on which is placed a filter element (3) consisting of at least one sheet based on fibers and filled with organic and/or inorganic powders. The invention finds its application in all the industries which consume water and especially the crude oil processing industries and the chemical, papermaking and agri-foodstuffs industries.

Abstract: Blood filtration devices and methods of filtering are disclosed. In part, a blood filtration device is provided comprising a housing defining an interior periphery. The device includes a rotating structure mounted within the interior periphery and defining with the housing an annular gap within the interior periphery, an inlet fluid path for allowing a blood product to flow into the annular gap, and the rotating structure including an exterior surface that includes a filter membrane. The filter membrane has a coating thereon comprising an insitu condensation product of a first electrophilically active, high molecular weight polyalkylene oxide and a second high molecular weight bifunctional diamino-polyoxyalkylene oxide derivative.

Abstract: An apparatus for the conversion of substrates both for analytical and preparative purposes in a flow-through and cross-flow reactor having compact porous discs and/or compact porous tubes as carrier for conversion reaction or preparative separations which compact porous discs and/or compact porous tubes are modified with substances being capable of specifically binding and/or converting said substrates by distributing the samples to be converted and/or preparatively separated and collecting the converted and/or separated substrates preferably in a low volume, wherein the distribution of the sample does not affect the carrier adversely.

Abstract: The present invention encompasses novel coated particles that are well suited for use as absorption media in chromatographic processes. The coated particles comprise a substrate, such as aluminum, silicon, titanium or zirconium oxide particles, containing polymerized silane moieties on a surface of the substrate. The silane moieties include two or three olefinic groups as well as at least on useful ligand. Methods of preparing these coated particles are also described.

Abstract: Compositions useful in separating molecules or catalytic conversions comprise a substrate, a zeolite or zeolite-like layer, a selectivity enhancing coating in contact with the zeolite layer and optionally a permeable intermediate layer in contact with the substrate the zeolite layer being in contact either with the substrate or the optional intermediate layer.

Abstract: The present invention provides a polymeric nonwoven web having a relatively small pore size, and made from mixtures of aramid and other non-aramid fibers. The fibrous nonwoven web has a high titer reduction with respect to coliphage PR772. The present invention provides the filter element incorporating the present inventive fibrous nonwoven web. The nonwoven web is also adapted to be use as human apparel and fashioned into garments.

Abstract: The present invention discloses a ceramic honeycomb structure comprising partition walls 3 that form mutually adjacent flow paths having a polygonal cross-section, and a peripheral wall 5 provided around the circumference of partition walls that hold the partition walls integrated into a single unit; wherein, the mean thickness of partition walls 3 is 0.05 mm to 0.13 mm, the mean thickness of peripheral wall 5 is greater than the mean thickness of partition walls 3, and the mean contact width between partition walls 3 and peripheral wall 5 satisfies a predetermined relationship. This ceramic honeycomb structure is able to inhibit the occurrence of chipping in the vicinity of the peripheral wall.

Abstract: The invention provides a high temperature, damage tolerant candle filter (4) made of a porous ceramic material which is designed so that, if it fails, it does not fail catastrophically. The ceramic candle filter includes a hollow tube (14) having an open end, a closed end and a porous outer wall therebetween. The porous wall is made of a fiber ceramic reinforcement material impregnated with ceramic particles and a fugitive material that is substantially removed from the fiber ceramic reinforcement material or partially converting into a permeable material to provide porosity. The reinforcement material is generally strong enough to absorb the initial explosion force created when the ceramic particle carrier fails during, for example, reverse pressurization of the candle filter, thereby preventing the ceramic pieces from becoming projectiles.

Abstract: A conventional coffee filter is replaced by a package containing a flavoring and in which a paper filter forms a wall. The filter-formed wall is the upstream wall of the package. When used in a conventional filter drip or automatic filter drip brewer, the result is a brewing system wherein the producing of a filtered filtrate of the coffee brew and the flavoring of the filtrate are performed as two separate and sequential steps.

Abstract: The present invention relates to a process for producing polymer beads incorporating solid particles and to the novel polymer beads per se. The invention provides a process for producing polymer beads incorporating solid particulate material, which process comprises producing a dispersion having a dispersed phase including one or more monomers also including solid particulate material, and causing said one or more monomers to undergo a polymerization reaction to form said polymer beads, wherein said dispersion further includes a solid phase dispersing agent for dispersing solid particles of material in the dispersed phase and wherein said solid phase dispersing agent reacts with at least one monomer to thereby become chemically incorporated in said polymer. The polymer beads comprise a polymer matrix having solid particulate material dispersed substantially uniformly therein and wherein the polymer matrix incorporates a solid phase dispersing agent chemically reacted into the polymeric matrix.

Abstract: A method for selectively removing leukocytes from a suspension which also contains platelets, such as a platelet concentrate or whole blood. The method includes passing the suspension through a filter which includes a polysaccharide-type coating. The coating may include one or more of hydroxypropylmethyl cellulose, hydroxybutylmethyl cellulose, dextran and hydroxyethyl starch. Also provided is a filter for selectively removing leukocytes from a suspension which also contains platelets. The filter includes a substrate which is coated with a polysaccharide-type composition.

Abstract: A ceramic composite comprising ceramic fibers and glass microparticles bound together as a porous matrix with a ceramic binder provides baffles for cryogenic fluids in a storage container.

Abstract: Apparatus for physicochemical separation and filtering constituents of fluids having a flexible leak-tight or semipermeable casing which tightly envelopes a filter material and inlet and outlet pipes for passing a fluid through the casing in contact with the filter material. The casing is made in a flat profile that can be formed into various shapes such as spirals, ribbons or the like.

Abstract: Fabrication and use of porous silicon structures to increase surface area of heated reaction chambers, electrophoresis devices, and thermopneumatic sensor-actuators, chemical preconcentrates, and filtering or control flow devices. In particular, such high surface area or specific pore size porous silicon structures will be useful in significantly augmenting the adsorption, vaporization, desorption, condensation and flow of liquids and gasses in applications that use such processes on a miniature scale. Examples that will benefit from a high surface area, porous silicon structure include sample preconcentrators that are designed to adsorb and subsequently desorb specific chemical species from a sample background; chemical reaction chambers with enhanced surface reaction rates; and sensor-actuator chamber devices with increased pressure for thermopneumatic actuation of integrated membranes.

Abstract: Composite polyamide reverse osmosis membranes are treated with an aqueous chlorinating agent at a concentration of 200 to 10,000 ppm for a time sufficient to improve flux, lower salt passage and increase the stability to base. In a preferred embodiment the membrane is treated with heated water at temperature of 40.degree. C. to 100.degree. C. before being exposed to the chlorine treatment.

Abstract: The present invention is directed toward a new zeolite membrane which exhibits a columnar cross-sectional morphology and preferred crystallographic orientation comprising a porous substrate having coated thereon a mesoporous growth enhancing layer and a layer of columnar zeolite crystals on said mesoporous growth enhancing layer, and wherein said mesoporous growth enhancing layer comprises nanocrystalline or colloidal sized zeolites, nanocrystalline or colloidal zeolite and metal oxide, or nanocrystalline or colloidal zeolite and colloidal metal, or nanocrystalline or colloidal zeolite, colloidal metal and metal oxide, and wherein said mesoporous growth enhancing layer has interstices of about 20 to about 2000 .ANG., and wherein said columnar zeolite layer is a polycrystalline layer wherein 99.9% of said columnar zeolite crystals have at least one point between adjacent crystals that is .ltoreq.20 .ANG..

Abstract: The present invention relates to silica materials and particles having surfaces which define an interior. The interior includes interior silicon atoms at least a portion of which is bonded to a substituted or unsubstituted alkyl moiety. In a preferred aspect of the present invention, the silica material also has surface silicon atoms to which are bonded substituted or unsubstituted alkyl moieties. A capillary tube coated on its inner surface with the silica material of the present invention is also disclosed. The silica materials of the present invention are resistant to degradation at high or low pH and are particularly useful as chromatographic stationary phases, especially for use in open tubular liquid chromatography and open tubular electrochromatography.

Abstract: The present invention provides a method and apparatus for separating a blood sample having a volume of up to about 20 milliliters into cellular and acellular fractions. The apparatus includes a housing divided by a fibrous filter into a blood sample collection chamber having a volume of at least about 1 milliliter and a serum sample collection chamber. The fibrous filter has a pore size of less than about 3 microns, and is coated with a mixture including between about 1-40 wt/vol % mannitol and between about 0.1-15 wt/vol % of plasma fraction protein (or an animal or vegetable equivalent thereof). The coating causes the cellular fraction to be trapped by the small pores, leaving the cellular fraction intact on the fibrous filter while the acellular fraction passes through the filter for collection in unaltered form from the serum sample collection chamber.

Abstract: Magnetic particles which comprise a core of a magnetic material surrounded by a mixture of a fibrous material and a solid binding agent. The particles may be embedded in a polymer resin which incorporates sites, which are selective for particular ions, to form composite magnetic resin particles. The composite magnetic resin particles may be used for the removal of pollutant ions from an aqueous solution in which they are contained.

Abstract: A method for forming a hollow fiber bundle unit for insertion into an assisted breathing device comprising spinning a hollow fiber or hollow fibers, collecting multiple fibers into a bundle, filling the walls of the hollow fibers within the hollow fiber bundle with an humectant, coating the hollow fibers containing the humectant with a solution of an adhesive material, forming and drying the hollow fiber bundle coated with the solution, and preparing the hollow fiber bundle coated with the solution for insertion into the assisted breathing device.

Abstract: The microfiltration membrane cartridge filter is formed by pleating a porous membrane sheet having a mean pore size of 0.05 to 10 .mu.m, rounding the sheet in the form of a cylinder, liquid-tightly sealing joints of the rounded sheet and liquid-tightly sealing opposite ends of the cylinder by end plates, wherein pores in the opposite end portions of the cylindrical pleated membrane are filled up with a high molecular-weight polymer to reject the liquid-permeation of the opposite end portions of the cylindrical pleated membrane. The microfiltration membrane cartridge filter can be made wet to water easily so that an integrity test for the filter is carried on easily.

Abstract: The present invention relates to a mineral eluting material for drinking water with granite as raw material and manufacturing method thereof and a structural body of mineral eluting material. The mineral eluting material includes granite crushed to sizes of 0.075.about.0.145 mm, submerged in 3.about.10% glucose solution for 24 hours, baked at 380.degree..about.400.degree. C. for 12.about.24 hours, and cooled at room temperature in a tightly sealed vessel. The structural body according to the present invention is manufactured by piling up granular granite and silver activated charcoal in 2-10 layers respectively and alternately in a cylindrical column. Water having passed the structural body according to the present invention comprising granular granite contains no impurities and abounds in minerals.

Abstract: A method for removing leukocytes from a leukocyte-containing suspension comprising passing said suspension through a filter including a nitrocellulose membrane having a pore size of 5-15 .mu.m.

Abstract: A combined cardiotomy and venous blood reservoir according to a preferred embodiment of the invention provides a separate in-flow path for both cardiotomy fluid and for venous blood, and includes a cardiotomy fluid filter element also serving as an initial de-foamer. The cardiotomy fluid is de-foamed, filtered, and again de-foamed. The venous blood is de-foamed, and then both fluids are combined for flow from the reservoir. The filter area provided for cardiotomy fluid is advantageously separated from the area of a final de-foamer element. Thus, both the cardiotomy fluid and venous blood may flow through this final de-foamer element simultaneously along separate flow paths. The reservoir design provides greater freedom in selecting adequate filter area for the cardiotomy fluid, while allowing the selection of effective de-foamer element areas in order to achieve acceptable flow rates for both cardiotomy fluid and for venous blood under various conditions of operation for the reservoir.

Abstract: A composite filter media includes a fibrous filtration layer of randomly oriented fibers and one or more pleatable stiffening layers which enable the composite filter media to be pleated and hold or retain its pleats. The pleatable stiffening layer(s) may enhance the dirt holding capacity of the composite filter media especially when positioned upstream of the fibrous filtration layer. The composite filter media may also include a flexible covering layer which functions to block the loss of fibers from the fibrous filtration layer. Preferably, the mean fiber diameter of the fibers in fibrous filtration layer increases and the density of the fibrous filtration layer decreases throughout the thickness of the fibrous filtration layer from one major surface to the other major surface of the fibrous filtration layer.

Abstract: Novel blood cell fractionation means utilizes conventional filters coated with high molecular weight polyethylene oxide derivatives crosslinked to prevent leaching from filter surfaces. These fractionation means have a special efficacy in binding white blood cells from whole blood while simultaneously allowing red cells and platelets to pass in the effluent phase.

Abstract: Filtration medium is formed of a mass of nonwoven melt blown support and filtration fibers which are integrally co-located with one another. The support fibers have, on average, relatively larger diameters as compared to the filtration fibers which are integrally co-located therewith. Preferably, the filtration medium is disposed within at least one annular zone of a filtration element, for example, a disposable cylindrical filter cartridge having an axially elongate central hollow passageway which is surrounded by the filtration media. A depth filter cartridge in accordance with the present invention may thus be formed having one or more additional filtration zones (which additional filtration zones may or may not respectively be provided with integrally co-located support fibers) in annular relationship to one another.

Abstract: A part still wet with water or an aqueous type detergent adhering to the surface thereof is drain washed in a washing tank using a hydrophobic dewatering cleaning agent. In this operation of dewatering cleaning, the hydrophobic dewatering cleaning agent stored in the washing tank is circulated between the washing tank and a reserve tank to deprive the hydrophobic dewatering cleaning agent of water entrained thereby by means of a concentration type filter inserted in a path laid for the circulation. A hydrophobic filter is mainly used as the concentration type filter. The dewatering cleaning is continued and meanwhile the consequently isolated hydrophobic dewatering cleaning agent is exclusively returned to the washing tank. As a result, the water concentration in the hydrophobic dewatering cleaning agent stored in the washing tank can be constantly kept below a prescribed level.

Abstract: An apertured film extruded from a crystalline, thermoplastic, extrudable fluoroplastic material. The film includes spaced-apart strand segments defining apertures therebetween and has at least 10 strand segments per inch. The film has a thickness of 2-12 mils and a Frazier air permeability number in the range of 200-2,000. The invention includes a process for preparing an apertured thermoplastic film by a single-sided embossing method. The process includes the steps of extruding in the machine direction, a film of a molten, crystalline, thermoplastic, extrudable, fluoroplastic material. The molten extruded film is passed in the machine direction through the nip of two metal rollers. One of the rollers has a substantially smooth surface, having a convex configuration as viewed from a direction substantially parallel to the axis of the roll, such that the diameter in the center of the roll is in the range of 8-12 mils greater than the diameter at the ends of the roller for a 40 inch roller.

Abstract: An electrochemical biosensor for determining the level of a target chemical in a biological fluid includes an electrochemical system including a enzyme substrate which reacts with the target chemical to yield a system signal related to the concentration in the biological fluid of said target chemical. The biosensor includes a first membrane for immobilizing the enzyme substrate. The first membrane has a porosity permitting passage therethrough of the target chemical to react with the enzyme substrate and a surface exposed to the biological fluid characterized by electron donor site susceptible to facilitating attachment thereon of proteins and fibrin which impair the system signal. A second membrane is bonded to the electron donor sites of the first membrane.

Abstract: Supported inorganic membranes capable of molecular sieving, and methods for their production, are provided. The subject membranes exhibit high flux and high selectivity. The subject membranes are substantially defect free and less than about 100 nm thick. The pores of the subject membranes have an average critical pore radius of less than about 5 .ANG., and have a narrow pore size distribution. The subject membranes are prepared by coating a porous substrate with a polymeric sol, preferably under conditions of low relative pressure of the liquid constituents of the sol. The coated substrate is dried and calcined to produce the subject supported membrane. Also provided are methods of derivatizing the surface of supported inorganic membranes with metal alkoxides. The subject membranes find use in a variety of applications, such as the separation of constituents of gaseous streams, as catalysts and catalyst supports, and the like.

Abstract: A ceramic fired composite filter media having a uniform pore size, the media consisting essentially of a porous cordierite substrate having a surface having pores of non-uniform diameter, the diameter ranging from <1 to 200 .mu.m; and a layer of porous ceramic oxide having pores having a uniform diameter bonded to the surface of the cordierite substrate, the layer of ceramic oxide comprised of ceramic oxide particles having a particle size sufficiently large to avoid substantial penetration of the pores in the surface of the cordierite.

Abstract: A bonded multi-component filter medium preferably contains at least two active components, namely, activated carbon adsorbent and a blend of at least two organic polymer absorbents. The medium is prepared by adding a selected quantity of carbon of a preselected size to a mixer, then wetting the activated carbon with a water-based aliphatic resin binder adhesive, preferably also with a surfactant, thus eliminating the static charge on the carbon, then adding hydrophobic absorption bonding polymers to the mixer, then thoroughly mixing the hydrophobic absorption bonding polymer with the carbon in preselected proportions, until both the carbon particles and the polymer particles are effectively coated with the binder adhesive. After thoroughly mixing, the medium mixture is preferably poured into filter cartridge forms, and then air-dried at room temperature and low humidity, to cure the aliphatic resin adhesive binder.

Abstract: The present invention relates to a method and to a device for separating plasma from whole blood. The method and device utilize a permeable non-glass fiber matrix containing a polyol which is capable of clumping red blood cells. The matrix, in the absence of such a polyol, would otherwise be porous to red blood cells. The polyol-containing matrix has a first surface and a second surface such that a whole blood sample which is applied to the first surface flows directionally toward the second surface. Plasma separated from whole blood becomes available at the second surface of the matrix and can be tested for the presence of a particular analyte, such as glucose or fructosamine, as provided by multi-layer test devices of the present invention.

Abstract: A filter element for use in an oil filter is composed of main fibers of at least 5 .mu.m diameter and micro fibers of less than 5 .mu.m diameter. The micro fibers are filled in a density of 0.005 to 0.02 g/cm.sup.3. A slurry including the fibers is drawn into a suction unit through suction openings to form a molded body. The filter element is given a density gradient such that the micro fibers are denser in the inner periphery than in the outer periphery. Following the drawing step, the molded body together with the inner mold is removed for subsequent dehydration and heating. During those processes the inner mold is kept located within the molded body.

Abstract: Inorganic composite membrane containing molecular sieve crystals, comprising a macroporous support to which molecular sieve crystals and modifications thereof have been applied substantially as a monolayer, said crystals and modifications thereof having been oriented so that, toa substantial extent, the pores of the sieve crystals form a significant included angle with the support surface, there being present between the crystals a gastight matrix, at least gastight to a degree sufficient under practical conditions.