Abstract: An assembly for sealing the access passageway to a detector chamber in a scintillation counter instrument. The seal is designed to prevent the entry of any exterior light or environment that could affect the counting or scintillation process when a sample is positioned in the detector chamber. The sealing mechanism operates in conjunction with the scintillation instrument's flexible transport or elevator mechanism that moves a sample containing vial into the detector chamber. A plurality of rotating blades engage the elevator mechanism to form the tight seal. Included in the arrangement is a redundant system to provide a dual sealing capability. The sealing mechanism operates in conjunction with the flexible transport member which allows itself to be centered by the sealing mechanism to achieve the required light seal.

Abstract: A column for use in DNA synthesis. The column is transparent and is disposable to allow access to the resin beads within the column. The column includes end caps which are engageable with a housing and a screw to secure the column in the housing.

Abstract: An ultracentrifuge rotor comprising a body portion formed as a bowl with a central open chamber defined by a thin, cylindrical wall extending from a supporting base and a plurality of nested rings of filament windings surrounding the cylindrical wall for strengthening and stiffening same. The nested rings result in a uniform filament density throughout the ring assembly.

Abstract: A double beam photometric flow cell for high pressure liquid chromatography having illuminated sample and reference passageways therein, the sample passageway receiving flowing fluid sample fractions for analysis. Regulating apertures control the relative amount of light passed through the passageways such that the light energy through the reference passageway exceeds that through the sample passageway. This reduces the contribution of the reference path to "shot noise" in the photometer output signal.

Abstract: An improved nondispersive infrared gas analyzer having at least one pneumatic or Luft-type detector and at least one black body type detector located one behind the other along the optical axis of the analyzer. In the preferred embodiment, a black body detector is exposed to radiation from a sample cell through an intervening pneumatic detector. The pneumatic detector absorbs radiation at specific infrared wavelengths, while the black body detector absorbs radiation substantially uniformly at all wavelengths. Signals from the pneumatic detector and the black body detector are combined electronically in an improved signal processing circuit to provide an output signal that is substantially free of the effects of disturbing influences such as infrared source intensity variations, mechanical vibrations and shock, and the presence of interfering compounds.

Abstract: An improved source assembly for use in infrared gas analysis instruments. A rotating reflector having a generally conical shape is provided with a reflective interior surface. An infrared source directs infrared radiation against the reflector from a predetermined number of fixed directions each of which is generally perpendicular to its axis. One or more blocking members, which are aligned generally parallel to the axis of the reflector, pass between the source and the reflective surface as the reflector is rotated. In operation the source assembly generates a plurality of chopped beams of infrared radiation which, because they emanate from a single source and are reflected from the same reflective surface, have a highly uniform intensity. This uniformity of intensity allows the source assembly to illuminate a plurality of sample cells that are distributed circumferentially about the axis of the reflector.

Abstract: A function generator responsive to clock pulses for developing an analog signal in the form of a digitally approximated parabola.

Abstract: A liquid transfer valve including a movable valve portion. A second valve portion is movable with respect to a first valve portion to allow probes to extend therethrough to pick up a liquids. Upon probe retraction, the second valve portion is movable to a position which allows the liquids to be injected into the valve where they are diluted, mixed, and carried to a remote detector or delivery point.

Abstract: A wavelength calibration solution comprising from about 0.025 to about 0.140 molar neodymium and from about 0.135 to about 0.550 molar samarium, wherein the neodymium is present as a neodymium ionized constituent and the samarium is present as a samarium ionized constituent.A method for checking the wavelength accuracy of spectrometers or spectrophotometers of the type comprising measuring the absorbance (A) or percent transmittance (% T) of a wavelength calibration check solution versus a blank at more than one wavelength. The method is characterized in that the above solution is employed therein as the wavelength calibration check solution.

Abstract: An improved liquid sample injection valve having a metering rod for receiving a sample of a test liquid in a sample loading assembly and delivering that sample to a sample evaporating assembly that is connected to a gas chromatograph. In the sample loading assembly there is provided a sample chamber housing having an improved sealing and mounting arrangement that provides a high degree of thermal isolation between the sample loading and evaporating assemblies. A novel mounting arrangement for the metering rod allows the latter to be conveniently changed without disassembling the valve. The sample evaporating assembly is provided with a flow control element which minimizes deal volume and provides improved sample removal and evaporation characteristics.

Abstract: A variable slip drive system for driving a variable speed induction motor. The system includes a tachometer for providing a signal proportional to the speed of the motor and a slip oscillator. The output of the tachometer and slip oscillator are combined by a motor drive oscillator to provide a motor drive signal. The frequency of the motor drive signal equals the tachometer signal, less the frequency of the slip signal. The motor drive signal is converted into a proportional, three-phase, high power signal for powering the motor. The frequency of the slip signal is controlled so as to be proportional to the motor speed as a means of optimizing the motor's performance.

Abstract: A torque-transmitting connector is disclosed which fits between a spindle and the walls of a bore in a rotating member. The connector includes a sleeve encircling the spindle and two flanges located at its opposite ends. Each flange is initially frustoconical, and is forced into substantially a disc shape to grip the spindle and the wall of the bore. The flange at the bottom of the bore is flattened first by a small diameter punch acting against the other end of the sleeve; and the other flange is then flattened by an annular punch encircling the small diameter punch.

Abstract: Apparatus for transporting elongated sample holders in a sample holder storage compartment past an operating station at which sample tubes contained in the sample holders may be removed and then returned to the sample holders. First and second parallel conveyors on opposite sides of the operating station drive the holders toward and away from the operating station. Lateral drive means engage the holders in longitudinal stop positions at opposite ends of the conveyors and drive them laterally between the conveyors to lateral stop positions, one of the holders during lateral movement being driven into and away from an operative position at the operating station. Encoded label means are displayed on each sample holder for indicating the incremental spacing between the sample tubes carried in the sample holder.

Abstract: A membrane type amperometric gas sensor is provided with a pressure equalization passage between the exterior and interior of the cell in which the electrodes are located. Cell fluids move into and out of the passage as necessary to maintain the pressure inside the cell substantially equal to the pressure outside the cell over a wide range of pressures and temperatures. A movable fluid plug or seal located in the passage protects the fluids inside of the cell from contact with the gas being sensed and from the atmosphere for all permissible values of pressure and temperature.

Abstract: A process for generating high resolution conductive patterns on an insulating substrate. A photosensitive resin coating applied to the surface of a substrate is exposed to a suitable light source through a mask. The unexposed portion of the coating defines the desired conductive pattern which is then coated with a low temperature melting glass powder. The substrate is fired to sinter the glass pattern and fuse it to the substrate. The substrate is then coated with a slurry of fine metal particles suspended in a volatilizable carrier. The substrate is again fired to sinter the metal into a united mass and causing it to fuse only with the low temperature melting glass pattern. The unadhered portions of the metal coating are removed by a washing operation. An exclusively metallic layer is thereby formed on a high resolution glass pattern intermediate layer supported by the substrate.

Abstract: An electro-optic display device having at least two separate compartments for receipt of electro-sensitive material that is utilized in the formation or establishment of a display symbol as a result of an electrically imposed field. One compartment in the display contains the electrodes which form the various segments of the variable symbol to be displayed. The other compartment is the background area that will contrast visually with the segment portions that make up or establish the symbol to be displayed. The choice of material makes the background compartment optically equivalent to the portion of the symbol compartment that is not displaying a particular symbol. The electro-optic device preferably has a liquid crystal material with a dye to create a light absorption type of electro-optic display rather than a light modulation type of display. This invention allows dye displays that normally portray light characters on a dark background to be portrayed as dark characters on a light background.

Abstract: In a digital test instrument such as a digital ohmmeter for measuring and digitally displaying the resistance of an unknown circuit element, there is included an electrical continuity tester coupled to the input of the digital ohmmeter for instantaneously and digitally indicating electrical continuity. Connection of the electrical continuity tester to the input of the digital ohmmeter is achieved in a manner such as to not overload or otherwise affect the accuracy of the resistance measurement.