Abstract: A two-part concave-convex rupture disc for use in a safety pressure relief device comprises one part which is perforated with lines of small holes that introduce controlled weakness in the disc and the other part which acts as a seal. When the pressure in a fluid on the convex side of the discs exceeds a predetermined limit, the discs will reverse their direction of convexity and the metal of which the perforated disc is made will tear cleanly along the lines of perforation and rupture so as to release the fluid in which the excess pressure occurred. The pressure at which the rupture occurs is determined by the choice of the size and spacing of the perforating holes, as well as the choice of the thickness, the material of which the discs are made, and the pressure used to form the discs.

Abstract: An implantable plate for joining together two pieces of a broken bone is formed to have a plurality of elongated holes for the screws that fasten the plate to the bone on both sides of the fracture. The screws are positioned at the end of the elongated hole that is farthest from the fracture. The portion of each elongated hole that is not occupied by the screw is filled with a cushion of elastic material that may be deformed elastically when the screw shank is pressed against it, thereby allowing lateral movement of the screw in the hole. When the plate is implanted in the body of a person and fastened to a fractured bone by means of screws through the elongated holes, the plate stabilizes the bone pieces but permits the screws, and hence the bone pieces, to move a short distance back and forth in the direction of the axis of the bone in order to promote healing.