Abstract: A magnet assembly for a small scale NMR spectroscopy apparatus suitable for laboratory or home use, generally comprising two permanent magnets facing one another so that the facing surfaces have opposite polarities, a pole cap on each of the two facing surfaces of the permanent magnets, and a plurality of radially polarized canceling magnets disposed about the permanent magnets and pole caps. The design and position of the radially polarized canceling magnets about the tapered pole caps reduces leakage of the magnetic field, to maintain the magnetic field strength and homogeneity within the test region, without a disadvantageous increase in the size, weight and cost of the NMR apparatus. A curved edge ring shim may be used to increase magnetic field homogeneity in the test region. Also provided is a method for measurement of glucose concentration in a fluid using NMR spectroscopy.

Abstract: A magnet assembly for a small scale NMR spectroscopy apparatus suitable for laboratory or home use, generally comprising two permanent magnets facing one another so that the facing surfaces have opposite polarities, a pole cap on each of the two facing surfaces of the permanent magnets, and a plurality of radially polarized canceling magnets disposed about the permanent magnets and pole caps. The design and position of the radially polarized canceling magnets about the tapered pole caps reduces leakage of the magnetic field, to maintain the magnetic field strength and homogeneity within the test region, without a disadvantageous increase in the size, weight and cost of the NMR apparatus. A curved edge ring shim may be used to increase magnetic field homogeneity in the test region. Also provided is a method for measurement of glucose concentration in a fluid using NMR spectroscopy.

Abstract: A liquid nitrogen Dewar includes a spun can for the liquid nitrogen, which spun can is surrounded by an exterior shell. Between the exterior shell and the can is an evacuated space containing a second shell that functions as a radiation shield. The can and both shells are formed of an aluminum alloy having a very high percentage of aluminum. The exterior can surface, interior surface of the exterior shell, and both surfaces of the second shell have clean, non-pitted, smooth, matted, smut free and etched appearances free from discoloration and stains so that these surfaces have low radiation emissivity properties and there is a minimum amount of radiant energy transmitted from the exterior shell to the can and reduced heating of the liquid nitrogen in the can. Each of the surfaces is initially polished, either mechanically, electrochemically or chemically, and then chemically treated with an etchant of nitric acid and hydrofluoric acid for a sufficient duration to achieve the desired appearance.

Abstract: A solids excluding subsurface fixed liquid decanter is used primarily to decant the settled liquid above the decanter. The decanter has no moving parts and will discharge this liquid at a constant flow rate regardless of the liquid head pressure above the decanter over the time of decant. The decanter is designed to exclude solids and liquid from entering the confines of the device during the fill and mixing cycles of an SBR waste treatment process. During the aeration cycle, air is directed into a bell or hood of the decanter to replace any absorption or leakage in vent piping of the decanter. The decanter also has a mechanism for skimming the surface of the liquid volume for removing floating solids that are undesirable to the process.

Abstract: A mixing apparatus is composed of a vertical cylindrical shell having a mixing space divided into multiple pass annular mixing chambers by a concentrically arranged cylindrical shroud, and tubes. An outermost chamber houses a jet nozzle which provides high velocity motive jet tangentially into the annular outer riser chamber, an injector and specially constructed baffles to cause an ascending generally helical mixing to occur. Provisions are made for recirculating part of the mixed fluids from an intermediate downcomer passage to the outer riser chamber.

Abstract: Vapor from a boiling cryogenic liquid contained in a cryostat is warmed prior to discharge by passing said vapor through a heat exchanger for transferring heat at ambient temperature to the escaping vapor whereby condensation of atmospheric moisture on the cryostat is minimized.

Abstract: Component coils for providing a desired magnetic field distribution, which coils are subject to interaction via mutual inductance thereof, are connected each to respective current regulated power supplies whereby the interaction is compensated. Circuits are provided to control selected pluralities of interacting coils via persistence switches with minimum number of control leads in order to reduce the thermal communication to the interior of a cryostat housing the magnet and persistence switches.

Abstract: The thermal loss incurred through a fill and vent conduit of a cryostat is minimized by inclusion therein of a central coaxial member. Thermal energy transfer is desirably promoted by radiation between the interior surface of the fill and vent tube and the central coaxial member by enhancement of the emissivity of the respective facing surfaces. For a tubular central member dual paths to respective pressure relief valves are obtained.

Abstract: An improved cryostat for the superconducting magnet of an NMR spectrometer comprises a nested structure of isothermal shells surrounding a thermally conductive central reservoir of substantially spherical shape containing liquid helium in which the superconducting solenoid remains operational when only partially immersed. A radiation shield surrounding the central reservoir is cooled by the boil-off of escaping helium vapor. The radiation shield is enclosed within a isothermal shell maintained at the temperature of liquid nitrogen by thermal contact with a liquid nitrogen reservoir disposed above the region of the central reservoir and shielded therefrom by a wall of the isothermal shell. An outer radiation shield surrounds the liquid nitrogen reservoir and associated isothermal shell and the outer radiation shield is maintained at a temperatures of the order of 180.degree. K. by an external refrigeration facility.

Abstract: Apparatus and method for reduction of noise in NMR signals during high power heteronuclear decoupling experiments. A material is introduced into the evacuated area of the variable temperature probe to decrease collisional probability of ions generated in the interwall space of the evacuated envelop.

Abstract: A persistence switch comprises a diode and superconductive wire in thermal contact with the diode. The heat evolved by current through the forward biased diode raises the temperature of the superconductor above the transition temperature. The diode characteristic of the switch permits a plurality of such switches to be arranged in a network for selection by a relatively few signal conductors.