Abstract: In preparing dentures, hardened mould material surrounds the denture. This mould material is adhered inside a denture flask with a housing having two separably matable portions. To remove the hardened mould material from the flask, the flask is mounted in a mould press having a shaft, with one of the portions is restrained against movement along an axis of travel of the shaft. A portion of the mould material at an end of the restrained flask portion is available for contact with the shaft along the axis of travel. A capped end of the shaft is forcefully advanced against the adhered mould material therein, thereby breaking the adhesion. After this is done, the denture flask is dismounted from the mould press and the hardened mould material is removed from the first flask portion. If necessary, the process is repeated with the other housing portion.

Abstract: A system for the dissolution of gas in a large body of liquid comprising an impeller positioned below the surface of the large body of liquid; a floating hood positioned over the impeller and of sufficient size to capture undissolved gas; a conduit for introducing a feed gas stream beneath the floating hood and directly into the large body of liquid; at least one segregation ring positioned under the floating hood and extending below the surface of the large body of liquid such that a first inner region between the ring and the impeller, and a second outer region between the ring and an outer diameter of the floating hood are created, and a back pressure regulator located in the floating hood adjacent to the outer diameter of the floating hood.

Abstract: Oxygen or other gases are dissolved in large bodies of liquid by injection under a baffle for passage into a submerged hollow draft-tube-impeller means assembly for downward passage therein. Liquid containing dissolved gas is dispersed throughout the body of liquid, while any undissolved gas is effectively recovered and recycled.

Abstract: A shell and tube heat exchanger reactor with forced circulation is used to improve heat and mass transfer for exothermic liquid--liquid, gas-liquid and gas-liquid-solid reactions. Enhanced productivity and selectivity are obtained.

Abstract: The invention is directed to a liquid phase oxidation process, wherein a first oxygen-containing gas is injected into the lower portion of a bubble column reactor vessel containing an oxidizeable organic liquid. A second oxygen-containing gas is further injected into the reactor at a point or points wherein the liquid is substantially depleted in dissolved oxygen prior to said injection. Oxygen from both the first and second oxygen-containing gases is used to oxidize the organic liquid.

Abstract: A shell and tube heat exchanger reactor with forced circulation is used to improve heat and mass transfer for exothermic liquid-liquid, gas-liquid and gas-liquid-solid reactions. Enhanced productivity and selectivity are obtained.