Abstract: Method for testing a liquid scintillation sample to determine whether it is separated into different phases. Scintillations emitted by the sample in response to radiation from an external radiation source are analyzed. If the distribution of the intensities of the scintillations has a characteristic indicating it is the superposition of the intensity distributions of scintillations emitted by two or more distinct phases, then the sample is adjudged to be separated into different phases.

Abstract: A kinetic method for directly assaying total bilirubin in a sample. The kinetic assay entails mixing the sample to be assayed with an azo reagent and measuring the rate of formation of azobilirubin, wherein the rate of azobilirubin formation is directly proportional to the concentration of bilirubin in the sample being assayed. The azo reagent comprises a diazotized aromatic amine and accelerator and the composition and pH thereof is selected such that the rate constants for the conjugated and unconjugated reactions are approximately equal and such that the half-lives of both reactions are greater than 1 second and less tha 5 minutes.

Abstract: In a spectrophotometer including a photomultiplier tube and an operational amplifier responsive to the current from the photomultiplier tube for generating a DC voltage proportional to light intensity, a method and means for simultaneously compensating for the dark current of the photomultiplier tube and the offset of the operational amplifier so that the output voltage of the operational amplifier is zero volts under dark conditions.

Abstract: An assay which is capable of determining the endogenous glycerol and endogenous triglycerides content of a sample without the necessity of performing a separate glycerol assay. The assay of the instant invention can be performed in a single cuvette and is made possible by the use of a novel reagent kit.The reagent kit is of the type comprising lipase; glycerol kinase; adenosine triphosphate; and at least one reagent capable of being used to assay glycerol-1-phosphate or adenosine diphosphate. This reagent kit is characterized in that the lipase employed therein is from Staphylococcus epidermidis NRRL B-12072. In the absence of an auxiliary agent, this lipase does not cleave triglycerides to glycerol. Accordingly, the reagent kit further comprises, as the auxiliary agent, a surfactant which is capable of activating the lipase. Because these surfactants do not absorb at either 340 or 520 nm, one can determine a sample's endogenous glycerol content and endogenous triglycerides content in a single cuvette.

Abstract: An improved hydrazine analyzer is disclosed wherein sample and electrolyte solutions are supplied from constant flow rate sources into a mixing chamber where they are premixed. The premixed combination of electrolyte and sample is then passed through a sensing chamber having a sensing thimble disposed therein. The thimble is of a porous material having a platinum wire electrode wound about the outside thereof and having a silver wire inserted into silver chloride salt on the inside thereof to form a reference half cell. As the electrolyte-sample mixture passes through the sensing chamber, a portion of the fluid passes from the outside of the thimble to the inside of the thimble wetting the silver chloride salt to establish electrical contact and provide the internal filling solution of the reference half cell.

Abstract: An integrating analog-to-digital converter for producing a digital output signal representing the value of an analog input signal which may have either a positive or negative polarity. The converter uses a switching circuit to reverse an integrator capacitor between charge and discharge periods so that the same input-signal-controlled current source can be used to both charge and discharge the capacitor. This results in inherent zero calibration because any offset errors during the charge cycle are cancelled out by equal and opposite offsets during the discharge cycle.

Abstract: A test tube holder for insertion into a cylindrical test tube cavity in a centrifuge rotor to support a plurality of relatively small test tubes within the rotor cavity. The holder includes a body whose shape is substantially that of a cylinder or a longitudinal section thereof. The body has a plurality of small cavities for holding test tubes, the smaller cavities being spaced apart in a direction along the longitudinal dimension of the body. Each of the smaller cavities is arranged at an angle relative to the longitudinal dimension of the body, and each has a mouth opening onto an exterior surface of the body. The test tube holder further includes means for orienting the holder in the centrifuge rotor test tube cavity so that the mouths of the smaller cavities face the rotational axis of the centrifuge rotor when the test tube holder is inserted into said centrifuge rotor test tube cavity.

Abstract: A large diameter air driven centrifuge rotor which holds a plurality of centrifuge tubes in a fixed horizontal position. The rotor is designed to operate in a stable and smooth condition on a rotor seat which is smaller than the diameter of the rotor. Although the rotor essentially covers the rotor seat portion of the centrifuge, the rotor is designed in such a manner that the air flow from the driving air being exerted on the rotor will properly exit from between the rotor and the seat without affecting a stable smooth operation of the rotor.

Abstract: A fluid-containing means for each bore of a centrifuge rotor is disclosed which combines a self-capped tube and a floating cap resting on the top of the tube and arranged to resist deformation of the tube by the centrifugal forces developed therein. The floating cap has an annular skirt which engages the top of the tube and which is sufficiently thick in cross-section to prevent deformation of the floating cap. The floating cap is formed from a relatively light plastic, having a density less than that of the centrifuged fluid, thereby preventing bottoming of the floating cap in the bore in the event of rupture of the tube.

Abstract: A multiplexed display system which prevents closely positioned electrodes from causing erroneous displays. The electrodes are divided into selectively enabled groups. The electrodes are connected to switching circuits in a pattern such that the first one or more electrodes in each group are not connected to the same switching circuits as any of the electrodes in the preceding group, and the last one or more electrodes in each group are not connected to the same switching circuits as any of the electrodes in the next succeeding group.

Abstract: A centrifuge tube holder designed for use in a centrifuge rotor to hold a plurality of small volume tubes in such a manner that, when the centrifuge rotor is at rest, the tubes will be oriented at an inclined angle, but will assume essentially a horizontal orientation when the centrifuge rotor is operating. The holder provides improved collar support for the centrifuge tube during centrifugation and also provides for the inclusion of a tube pivot point in the plate to enhance the proper movement of the tube from its at-rest position to the correct support position during operational speeds of the centrifuge rotor.

Abstract: A substantially enclosed centrifuge tube having a small fill or access port at one end. In its preferred form there is integrally formed adjacent the fill port a neck or stem which is fused to hermetically seal the centrifuge tube to provide a permanent and complete seal of the centrifuge tube. A plug is securely mounted within the centrifuge rotor above the centrifuge tube when placed in the rotor to provide solid support adjacent the complete exterior surface of the tube. The interior of the plug is shaped to conform and mate with the upper end of the centrifuge tube. The use of a removable capping means placed on the centrifuge tube is eliminated. Access to the tube subsequent to the centrifugation run requires puncturing or cutting of the tube.

Abstract: A method and means for operating log converter circuits in which the method comprises the steps of sequentially conducting to the input of the log converter circuit signals representing a known transmittance (T) of 100% T, 10% T, 1% T, and 0.1% T, these signals covering the range of operation of the log converter circuit, storing the outputs of the circuit as signals representing an absorbance (A) of 0A, 1A, 2A, and 3A, respectively, conducting to the input of the log converter circuit an unknown signal, and utilizing a microcomputer to perform a linear interpolation of the output of the circuit with the unknown signal applied thereto using the previously stored 0A, 1A, 2A, and 3A signals.

Abstract: A containment apparatus for liquids. The device may be used with nephelometric instruments to contain sample liquids for serial dilution. The containment apparatus includes a tray section having a plurality of wells formed as an integral part of the tray section. The wells include well portions extending from the tray section such that the well portions are insertible into holes in the turntable rim to secure the tray section to the rim.

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

Abstract: A centrifuge tube holder which not only provides support for the tubes in a vertical orientation when placed on a workbench, but also horizontal and radial support when the tubes are placed in a centrifuge rotor. The tube holder has at least two sections which are pivotally connected to allow for upright or vertical orientation of the tubes when placed on a workbench. The two sections can be pivotally oriented with respect to each other to place the tubes horizontally in a centrifuge rotor at different radial angles with respect to each other with reference to the spin axis of the rotor. The holder also incorporates means for securely holding the tubes within the holder while they are being transported, so that the holder can be inverted without the escape of the tubes. On the other hand, the biasing or securing means for the tubes in the holder is eliminated when the holder is at rest on the workbench to permit convenient and easy insertion or removal of the centrifuge tubes.

Abstract: A temperature regulating apparatus which increases optical sensitivity and resolution of a liquid in a reaction chamber by heating while providing rapid cooling to prevent vaporization of the liquid within the reaction chamber. The apparatus includes a heat exchanger containing the reaction chamber and an insulating chamber surrounding the heat exchanger. A coolant may be passed through the heat exchanger to prevent boiling should a change in liquid flow make such occurrence likely. The change in liquid flow is monitored by an analyzer monitor, and the temperature in the reaction chamber is changed accordingly.

Abstract: A modular spacer concept is disclosed for use in centrifuge bores. The arrangement is such that various sizes of tubes are available to allow for different amounts of fluid which may be inserted therein for centrifugation. A plurality of substantially identical spacers are provided, each of which has an effective length equal to a predetermined standard difference in tube sizes. The lower surface of each spacer has a concave center portion adapted to fit the convex center portion of the upper surface of a tube, and the upper surface of each spacer has a convex center portion adapted to fit the concave center portion of the lower surface of a substantially identical spacer.

Abstract: An ink priming system for a multi-pen recorder of the gravity-fed capillary tube type comprises a gas manifold common to all of the ink bottles individually provided for each channel of the recorder. Individual control valves may be selectively actuated by the operator to prime each pen. When the control valve is closed, the gas pressure is bled off so that the inking system thereafter acts as a normal gravity-fed capillary tube system. A non-clogging inking system is provided by utilizing a short length of flexible thin walled tubing to supply ink to the movable recording pen. The length of this tubing is sufficiently short that evaporation of the ink solvent through the walls of the tube is accompanied by diffusion of the dye back to the ink bottle so that the concentration of dye in the ink at the end of the tube adjacent the recording pen does not exceed saturation value during prolonged periods of non-use of the recorder.