Abstract: A system for the storage or shipment of frozen or chilled biological materials consisting of a cryogenically insulated vessel which contains a heat sink material. The heat sink material is initially chilled to a very low temperature to keep the contents of the vessel cold. The heat sink may include a change of phase to provide extension of the possible shipment or storage time at a relatively constant temperature.

Abstract: An improved casing hanger for suspending a pipe string from a casing head at a well head employs a plurality of slip members having a series of teeth which are adapted for frictionally engaging the wedging surface of a slip bowl. The teeth have a profile which gradually tapers in accordance with the distance from a central portion of the slip member. The slip member is deformable from a first configuration wherein the edges of one surface of the slip member engage the pipe string while the central portion of the surface is spaced from the pipe string and the opposite surface of the slip member has a central portion which engages the slip bowl with the ends of the outer surface being spaced therefrom to a loaded configuration wherein the surfaces of the slip member engage the pipe string and the slip bowl along a series of substantially continuous arcuate paths.