Abstract: Selectively permeable asymmetric membranes are disclosed which are suitable for use in hemodialysis processes and the like. The membranes are produced from hydrophobic and hydrophilic polymers, and include a three-layered structure including a first dense thin skin layer which includes uniform pores of a size whereby proteins having a molecular weight of at least that of albumin are substantially rejected therefrom, an intermediate second layer in the form of a sponge and having a higher diffusive permeability than the first layer, and a third layer with a finger-like structure which provides mechanical stability. These membranes are preferably formed in the shape of hollow fibers, with the first layer as the inner layer thereof.

Abstract: A membrane for hemodialysis is prepared by casting, extruding or spinning a solution of a polyether-polycarbonate block copolymer and a swelling agent having a molecular weight of about 1,000 to about 20,000 Daltons, then partially evaporating the solvent, gelling and washing. The membrane has a top cut-off value less than about 68,000 Daltons, and hence is substantially impermeable to albumin, but nonetheless provides high permeability to water and to other small molecules.

Abstract: Processes for producing semipermeable membranes in the form of hollow fibers are disclosed including extruding a solution of a block copolymer including at least one hydrophilic polymer and at least one hydrophobic polymer while simultaneously injecting a gaseous or vaporous center medium into the center bore of the hollow fiber extrudate, including coagulating the extrudate so formed therefrom. The preferred process includes using air or the components of air as the center medium and employing a polyethyleneoxide-polycarbonate block copolymer to form the hollow fiber membranes.

Abstract: A filtration membrane is disclosed which has an ultrafiltration rate of between 200.times.10.sup.-4 and 500.times.10.sup.-4 ml/sec..times.cm.sup.2 .times.bar at 20.degree. C. and which is substantially impermeable to albumin of a molecular weight of about 44,000 or greater. A process for producing a filtration membrane is also disclosed in which a polymer solution is extruded with a center liquid under conditions such that the ratio of the volume of polymer solution to the volume of center liquid is within the range of from about 2:1 to about 4:1 to form a membrane extrudate.

Abstract: A method for setting the ends of bundles of hollow fibers in an end wall contained within a housing are disclosed, including providing a bundle of hollow fibers having adjacent open end faces, supplying a hardenable liquid material to those end faces so that this material can penetrate between the hollow fibers and into the interiors thereof, and exerting a positive pressure within the housing containing the hollow fibers to control the degree of penetration of the hardenable liquid material both between and within the interior of the hollow fibers.

Abstract: Method of treating a cellulosic hollow fiber which is being particularly adapted for use in hemodialysis or a similar extracorporeal treatment of blood.According to the described method the hollow fiber, possibly after rinsing with an alcoholic solution or fluorinated hydrocarbons, is exposed to swelling with use of an aqueous solution prior to drying and/sterilization of the hollow fiber.Examples of aqueous solutions can be water, water/glycerol, and water/glycerol/alcohol. Preferably said aqueous solution contains glycerol in an amount of 4-35%, such as 12-35%, preferably 16-35%.The aqueous solution can be applied to the inside and/or the outside of the hollow fiber so as to bring about a diffusive and/or a convective transport of water and/or glycerol into the hollow fiber wall.

Abstract: Plasmapheresis membranes of hydrophilic polycarbonates are disclosed, comprising polycondensates of bisphenol A and a polyalkylene oxide. These membranes which have a regular pore structure with smoothly rounded pores with openings without sharp edges, have an average pore diameter of about 0.01 to 0.8.mu., a porosity preferably above 65%, and a thickness of between about 50 and 300.mu.. Processes for preparing these membranes are also disclosed, including casting a 3 to 20 weight percent polycarbonate polymer solution onto a smooth surface, contacting the layer with a gelling medium prior to precipitation of the membrane, and subsequent precipitation of the gelled layer to form the membrane.

Abstract: Flow-through chambers, such as drip or expansion chambers, which are intended to form part of a duct for blood or other such sensitive fluids, are disclosed. The chambers include a housing, an inlet, an outlet, and a flow directing portion of the housing for directing the flow of the fluid from the inlet to the outlet. The flow directing portion of the housing is formed in a manner so as to deflect the flow of the fluid from the inlet towards the outlet in a gradual manner so as to protect the fluid within the chamber.

Abstract: Biologically active material such as an enzyme is bonded to a carrier containing hydroxyl groups by binding an isocyanate compound to the carrier and bonding the biologically active material to the bound isocyanate compound. Binding of the isocyanate compound to the carrier is achieved with the use of a non-toxic titanium based compound which catalyzes the formation of urethane bonds. The preferred non-toxic based titanium compound is an orthotitanium acid ester such as tetrabutyltitanate.

Abstract: A device is disclosed for collecting a liquid which has been separated into at least first and second fractions according to the densities of such fractions. The device comprises a stationary transferring element and a housing for said stationary transferring element. The housing is rotatable about an axis of rotation for the device and the housing and stationary transferring element provide a fluid communication space therebetween for fluid communication between the housing and stationary transferring element. The housing includes first and second outlet passages for passing said first and second separated fractions through the housing to first and second points in the fluid communication space, and the transferring element includes first and second outlet channels for passing the first and second separated fractions from the first and second points in fluid communication space through the transferring element.

Abstract: A rotatable rigid disc for separating a liquid into fractions according to the densities of such fractions is disclosed. The rigid disc includes an inlet for the liquid to be separated; at least two outlets for the separated liquid fractions; and a separation chamber in the form of an elongated, curved conduit. The conduit is fluidically connected to the inlet and the outlets, the outlets are positioned on the disc radially outwardly with respect to the inlet, and the outlets are positioned along the elongated, curved conduit so as to provide a separate collection location for each outlet and so that the densest fraction is separated by the outlet nearest to the inlet and the least dense fraction is separated by the outlet most distal from the inlet.

Abstract: Polyurethane molding compositions are disclosed which contain diisocyanates and polyols and/or polyurethane prepolymers and sorbic acid or cinnamic as a setting catalyst. A process for preparing such compositions is also disclosed. These compositions give a rapid initial hardening and therefore mold release properties, which contribute to increased production speeds. Moreover, the acids used are physiologically safe, so that the process may be used for the production of objects used in medical science. The acids may also be used in a physiologically safe mixture with a heavy-metal containing catalyst.

Abstract: Processes and apparatus for the removal of waste metabolites from metabolite-containing solutions are disclosed. The disclosed processes include alternatively adsorbing and desorbing the metabolites on a pair of adsorbent-containing columns, each column being maintained at a reduced temperature during adsorption and at an elevated temperature during desorption, with the columns being flushed subsequent to desorption and prior to their re-use for adsorption thereon.