Abstract: A device for the controlled release of an active material into an aqueous medium, e.g. body fluids, comprises a water soluble glass container in which the active material is sealed. The container wall has a region of reduced thickness which region dissolves before the remainder of the container wall to release the active material.

Abstract: A method of bonding a metal body to a ceramic body, particularly a method of bonding a TWT slow-wave helix to boron nitride support rods, involves depositing on one of the bodies an active metal layer, typically of titanium, to be sandwiched between barrier layers protecting it from oxidation. The assembly is formed and then heated to a temperature sufficient to cause the active metal to migrate into the surface of the ceramic, whereupon the temperature is further raised to cause the protective barrier layers to form a braze uniting the metal body to the now-metallized ceramic body.

Abstract: A method of making a single mode optical fibre directional coupler in which a pair of fibres (30,31) in side-by-side contact is subjected to a succession of drawing operations produced by traversing the fibres longitudinally through a flame (34) while stretching them between a pair of carriages (32,33) driven at slightly different speeds.