Abstract: A cutter element for use in a drill bit, comprising a substrate and a plurality of layers thereon. The substrate comprises a grip portion and an extending portion. The layers are applied to the extending portion such that at least one of the layers is harder than at least one of the layers above it. The layers can include one or more layers of polycrystalline diamond and can include a layer in which the composition of the material changes with distance from the substrate.

Abstract: A cutter element for use in a drill bit, has a substrate comprising a grip portion and an extension and at least a cutting layer affixed to said substrate. The cutting layer has a cutting surface and an interface surface, and the cutting surface includes a region of residual compressive stress, which functions as a preload or prestress so as to offset the effect of localized loading due to contact with the formation during drilling.

Abstract: The valvular infusion device is for the administration of drugs or supplemental fluids into a parenteral fluid stream for intravenous infusion to a patient. The device includes a main conduit for generally the continual flow therethrough of a parenteral fluid, and at least one second conduit in communication with the main conduit to permit the injecting of drugs or supplemental fluids thereinto for transport with the parenteral fluid to a patient. The second conduits have valve chambers and compressible, resilient valve means therein, to permit only one-way flow of the drugs or supplemental fluids into the main conduit. The second conduits are provided with syringe receiving and securing means to provide a source for activating the pressure sensitive valve means and the injection of the required drugs or supplemented fluids for a patient. Additionally provided is a valvular infusion device for the induction of general anesthesia, which permits the injection of drugs utilizing only one hand of a user.