Abstract: A method for producing hydrogen by controlling an exothermic reaction provides a metal, input to a reaction chamber, at a first flow rate. An acid is provided and input to the reaction chamber at a second flow rate. The combination of the metal and acid produces hydrogen under pressure in the reaction chamber. Hydrogen is output from the reaction chamber at a first pressure and at a third flow rate. The first pressure and the third flow rate are determined. Each of the first flow rate of the metal and the second flow rate of the acid are controlled as a function of the first pressure and third flow rate.

Abstract: An advanced mass gauge sensor is disclosed comprising a vessel having an interior surface which reflects radiant energy at wavelengths at least partially absorbed by a fluid or fluids contained within the vessel, an illuminating device or devices for introducing radiant energy at such wavelengths into the vessel interior, and detectors for measuring the energy per unit area of illumination within the vessel created by the radiant energy which is not absorbed by the fluid or fluids.

Abstract: The invention is a hand-held advanced ovulation predictor device, which includes an advanced ovulation predictor device body, an optical subassembly containing one or more hybrid lenses, an electronics assembly with a light source, switch, and battery, and, optionally, a cover. The preferred embodiment of this invention is one in which the viewing axis and the device axis are not collinear or coaxial, the specimen is illuminated with oblique or dark field illumination, the method of transmitting the light is through a light pipe, and one or more lenses are hybrid lenses.