Abstract: A biocompatible composite material and a method for its production are provided, wherein the composite material is made of a plastic matrix having a felt of collagen fibers contained therein, wherein the collagen fibers project out of a surface of the composite material, wherein the composite material is produced by a process involving:a) providing a collagen fiber felt wherein the collagen fibers have a structure of native collagen;b) impregnating the collagen fiber felt with one or more polymerizable monomers,c) partially curing the one or more polymerizable monomers to provide a polymer containing unpolymerized monomers, shortchain oligomers or both therein;d) removing the unpolymerized monomers and shortchain oligomers from the surface of the composite material to expose the collagen fiber felt on the surface,wherein the composite material is useful for the production of implants, especially dental implants and the implants can be colonized with human cells prior to implantation.

Abstract: At least part of the effluent from an ion exchanger flows past a first and second electrode. The electrodes are mounted within the pipe carrying the fluid so that they are visible from the outside. A DC voltage is applied between the electrodes. If the effluent contains a metal which should have been adsorbed by the ion exchanger, its presence is indicated either by a change in the voltage-current curve of the electrodes or a change in color of the cathode. Either a single metal or a group of metals may be precipitated.