Abstract: A process for the removal of urea from an aqueous solution containing same, which comprises subjecting the solution to reverse osmosis through a polymeric membrane prepared from a polymer of the formula--(--A--X--).sub.nwhereinA designates an aromatic moiety andX designates a bivalent linking group, the aromatic moiety A being chosen from the group consisting of phenyl, biphenyl, naphthyl, and mixtures of such moieties; and such moieties connected by means of linkages selected from --O--, --SO.sub.2 --, --SO--, --NH--, --CH.sub.

Abstract: A diaphragm pump is described comprising a reciprocated diaphragm for expanding and contracting a chamber communicating with a passageway connecting the housing inlet and outlet for pumping a fluid therethrough, and a pair of check valves in the passageway permitting the fluid to flow only from the inlet to the outlet. The check valves are disposed along laterally-spaced parallel axes and provide a forward fluid flow through both valves in the same direction along the laterally-spaced parallel axes, the outlet of one check valve communicating with the inlet of the other via a folded section of the passageway having two 180.degree. bends. Such an arrangement enables the diaphragm pump to be constructed in compact and/or miniaturized form.According to another described feature, the diaphragm pump is constructed in combination with the peristaltic pump having an inlet for a liquid to be pumped, and an outlet connected to the inlet of the diaphragm pump. Both pumps are driven by a common drive shaft.

Abstract: The present invention relates to novel aromatic diamino phosphoramides, thiophosphoramides and phosphoramidates and to a process for the production of same.

Abstract: A membrane separation cell is described comprising a stack of supporting members each supporting a membrane on each of its opposite faces and defining a permeate compartment therewith, and separating members interposed between the membranes of adjacent supporting members and defining feed solution compartments therewith. The separating members are plates formed with passageways connecting the feed solution compartments in series through the stack such that the feed solution flows through each feed solution compartment in an inward direction across one face of the separator plate and in an outward direction across its opposite face. The membrane supporting members are plates each formed with an outer rim having passageways for conducting the permeate from the permeate compartment in parallel out of the stack.

Abstract: An artificial kidney comprises means for introducing a prepared solution into the peritoneal cavity to draw toxic metabolites therefrom into the fluid, the fluid exiting from the cavity as peritoneal fluid; and a dialysis or ultrafilter separator containing a selective membrane having a high permeability to low molecular weight toxic metabolites but a low permeability to high molecular weight protein. The peritoneal fluid is circulated through the separator on one side of the selective membrane in the above-described closed-loop peritoneal circuit, the fluid exiting from that side of the membrane being returned to the peritoneal cavity. The artificial kidney further includes a single-pass reconstitution circuit wherein tap water is introduced into the inlet of a hyperfilter impermeable to ions and to organic matter; and a concentrate including sugar and salts is introduced into the water exiting from the permeate outlet of the hyperfilter to form a water concentrate solution.

Abstract: A method of producing porous tubes and hollow profile structures is characterized by coextruding different materials each through a separate section of a tube-forming extrusion die, one material being pore-forming and producing a porous wall section extending lengthwise of the extruded tube for providing a means of dispersing therethrough a fluid flowing internally of the tube, the other material being non-pore-forming or less pore-forming and producing a non-porous or less porous wall section extending lengthwise of the tube for providing mechanical strength to the tube.Also disclosed are a number of porous tube and hollow profile structures including various arrangements of porous and non-porous wall sections.