Abstract: A biocompatible hydrogel has between 0.3% and 30% by weight of dry matter of a copolymer formed at least from acrylamide, chitosan and N,N?-methylenebisacrylamide, as well as a diffusing agent. The diffusing agent is advantageously selected from the group consisting of inert ingredients which have biomechanical properties and active ingredients. A method of manufacturing the hydrogel by copolymerizing, washing, and adding the diffusing agent is provided, as well as a mechanical visco-supplementation system adapted for external or internal use that includes the hydrogel, and an external or internal mechanical visco-supplementation kit including an acrylamide and chitosan copolymer crosslinked with N,N?-methylenebisacrylamide, and a diffusing agent in solid phase or in suspension, the copolymer and the diffusing agent having been previously mixed in the form of a hydrogel during manufacture or being adapted to be mixed extemporaneously to form a hydrogel.

Abstract: A biocompatible hydrogel has between 0.3% and 30% by weight of dry matter of a copolymer formed at least from acrylamide, chitosan and N,N?-methylenebisacrylamide, as well as a diffusing agent. The diffusing agent is advantageously selected from the group consisting of inert ingredients which have biomechanical properties and active ingredients. A method of manufacturing the hydrogel by copolymerizing, washing, and adding the diffusing agent is provided, as well as a mechanical visco-supplementation system adapted for external or internal use that includes the hydrogel, and an external or internal mechanical visco-supplementation kit including an acrylamide and chitosan copolymer crosslinked with N,N?-methylenebisacrylamide, and a diffusing agent in solid phase or in suspension, the copolymer and the diffusing agent having been previously mixed in the form of a hydrogel during manufacture or being adapted to be mixed extemporaneously to form a hydrogel.

Abstract: In an acoustic wave reflector working in the sea, a sheet of air is set up between a reflecting plate and a perforated plate. This sheet of air forms a reflecting interface with the reflecting plate. A rubber bladder forms a container which, under the effect of the pressure of the water, feeds the sheet of air through the perforated plate. The thickness of this sheet of air is kept substantially constant up to the limit of submersion of the reflector. This makes it possible to increase the depth at which the acoustic reflectors are used.