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: A stable blood serum bilirubin reference composition characterized in that the composition possess a pH of from about 8.2 to about 9.2 and comprises (a) a sulfhydryl compound in an amount sufficient to enhance the stability of the bilirubin and (b) a chelating agent in an amount sufficient to bind all the metals present in the blood serum moiety of the composition. This blood serum bilirubin composition when stored in a gas impervious vial under an inert atmosphere has an excellent shelf life.

Abstract: A closed-loop drive system for variable speed induction motors for maintaining a constant slip frequency, regardless of motor speed. A slip frequency oscillator generates a signal having a frequency proportional to the desired slip of the motor and a tachometer generates a signal having a frequency proportional to the actual rotational speed of the motor. The stator frequency is the sum of the rotor speed and the slip frequency during acceleration and the difference between the rotor speed and the slip frequency during braking. Exclusive OR gates are used to add the slip frequency signal either to the tachometer signal or to the stator signal, the outputs of the gates being applied to a digital phase detector. The phase detector drives a voltage controlled oscillator which provides the stator signal. The output of the voltage controlled oscillator is used to trigger the slip frequency oscillator to prevent overlap of pulses to the digital phase detector.

Abstract: A method of closing or sealing a filler passage formed in a neck or stem protruding from the small access opening in the upper end of a substantially closed centrifuge tube. The neck is formed of a readily fusible material and a heat conductive cap member is positioned over the open end portion of the neck closely confining it therein. Heat and pressure are applied to the cap causing progressive portions of the neck to melt and fold into the filler passage where it forms a molten mass within the filler passage above the access opening to the tube. Heat and pressure are removed, permitting the cap to cool and the molten mass to solidify completely sealing or filler passage of the centrifuge tube. The cap is then removed and the centrifuge tube is fully prepared for centrifugation.

Abstract: In an overspeed protection system for a centrifuge apparatus of the type including a rotor driven by a drive motor, a transducer for providing a signal whose frequency is a function of the rotational speed of the centrifuge rotor, an oscillator for generating a reference signal having a predetermined frequency, means for mixing the rotational speed signal with the reference signal to provide a difference frequency signal, a filter coupled to the output of the mixing means for passing signals having frequencies below a predetermined frequency, and means coupled to the filter for disconnecting power to the drive motor in response to an output signal from the filter, there is disclosed an improvement comprising a frequency comparator responsive to the rotational speed signal and the reference signal for generating an overspeed signal when the frequency of the rotational speed signal exceeds the frequency of the reference signal, and means for combining the outputs of the filter and the frequency comparator at th

Abstract: A solid state electrode for use in determining ion concentration in an aqueous solution comprising an electrically conductive element; a first lipophilic-hydrophobic (hereinafter referred to as LH) layer in intimate contact with the element; and a second LH layer in intimate contact with the first layer. The first LH layer comprises an adhesive, LH polymer having an intrinsic viscosity of from about 0.4 to about 0.9 ml/g; and an LH plasticizer. The second LH layer comprises a LH polymer having an intrinsic viscosity of from about 1 to about 1.5 ml/g; an LH plasticizer, and an LH ion-selective ligand of the ion to be determined.Preferably, the first LH layer further comprises an LH charge carrier.As used herein, the term "lipophilic-hydrophobic (LH)" denotes an organic solvent soluble-water insoluble substance.

Abstract: A multi-contact rotary switch in which arcuate cam lobes on the planar faces of a rotatable disc-shaped cam rotor selectively engage a plurality of switch elements. Each switch element is attached to one of two switch blocks positioned adjacent to either cam rotor face. Slots in the switch blocks laterally confine the switch elements to preserve their alignment. A raised annular bearing on the cam rotor face maintains the position of the cam rotor relative to the switch blocks. Terminal extensions from the switch elements extend perpendicular to and away from the planar faces of the cam rotor.

Abstract: A method and apparatus for determining the wavelength of a light beam wherein the light beam is directed through a liquid crystal cell functioning as a variable retarder, wherein the voltage applied to the cell is ramped to vary the retardation of the cell between maximum and minimum values, wherein the light from the beam passing through the cell is detected, wherein the intensity of the detected light is monitored, which intensity alternately passes through maximum and minimum values as the retardation of the cell is varied between its maximum and minimum values, and wherein the number of times the intensity alternates between its maximum and minimum values is determined to provide an indication of the wavelength of the light beam.

Abstract: A membrane for use in the determination of calcium ion concentration in an aqueous solution, the membrane being of the type comprising a calcium ion selective component and a carrier material.

Abstract: In a system which measures a parameter of a sample and displays information relating thereto, a circuit including the component elements of the system for testing signal levels at test points within the system and for displaying the test signal levels. Switching means places the system in either a transducing mode for measuring the parameter or in a combined transducing/self-testing mode for simultaneous testing during transducing operation. The testing circuit includes an operator manipulated probe for contacting any of the test points and an analog multiplexer input of the system for multiplexing the probe test signal and the transducing signal. The multiplexed signals are converted to digital form and processed by the system's computer for display. In the combined transducing/self-testing mode, the probe test signal information is outputted to the system display while the transducing output thereto is inhibited.