Abstract: A method for obtaining an actual linear standard curve in a sandwich type of immunoassay where a first antibody bound to an insoluble support and a second unbound labelled antibody complex with the antigen contained in a test sample to form an insoluble antibody:antigen:labelled antibody complex which is then detected. Unbound unlabelled first antibody and/or unbound unlabelled second antibody are added to the reaction mixture to divert excess antigen away from the desired end-product complex, thus rendering the antigen of interest the rate-limiting factor in the overall immunoreaction. This results in a pseudo first-order reaction which produces an actual linear standard curve.

Abstract: A thermoelectric cooling design of the type having a nonconducting substrate mounting thermoelectric coolers is improved. Provisions for a flexible can and improved heat dissipation from the thermoelectric coolers are provided. For improved thermal response, the refrigerated vacuum can is provided with thin walls of high purity aluminum with the result that deformation of the wall surface, especially the bottom wall surface can occur both with respect to installation. A plurality of can heat sinks are placed on the walls of the can to form a unitary and locally rigid side wall to the can at the point of attachment. At least one thermoelectric cooler is communicated to the can heat sinks at a first side for receiving heat energy from the can. A second discharge heat sink is communicated to each thermoelectric cooler for dissipating heat energy from both the can and the thermoelectric cooler.

Abstract: A composite material centrifuge rotor and process of construction of the rotor is disclosed. A rotor having high stiffness of fibers, preferably carbon, bound together with resin is disclosed. The rotor includes a top disk, a bottom disk and a spacer belt spacing the two disks apart to form a rotor assembly. The top and bottom disks are fabricated by overlying multiple layers of tape, the tape being made from longitudinally extending and parallel fibers held together with resin. The tapes are stacked in multiple layers normal to the spin axis of the rotor so as to lie within the plane of the centrifugal force exerted by the rotor. Successive layers of tape are oriented so as to vary the longitudinal direction of the fiber with respect to a preselected radius vector from the spin axis of the rotor.

Abstract: The present invention comprises a method and means for stabilizing the frequency difference between the component frequency modes in the beam of a gas laser influenced by Zeeman splitting. Stabilizing the frequency difference makes constant the frequency of the beat signal obtained from heterodyning the component modes. Stabilization is obtained by accurately controlling the difference in frequency between the component frequency modes to provide a selected separation, preferably 250 KHz, with deviation maintained at less than two KHz. The difference in frequencies is controlled independently of the individual frequency or intensity of either of the component frequency modes, or of their relative position within the "Doppler broadened" spectral profile characteristic of the lasing material.

Abstract: In a double thermal coupled radiometer for preferable use with a centrifuge, an improved radiometer configuration is disclosed. The isothermal radiometic system improved is of the double junction variety (preferably copper-constantan-copper) and includes a black body housing defining a central concavity. The central concavity has a black body disk at the bottom thereof. The disk is preferably suspended by a copper and a constantan wire with one junction formed on the surface of the disk and the other junction formed on the surface of the housing. The improvement includes a plurality of and preferably three annular baffles defining central, circular and preferably concentric opening. These baffles are lodged in the opening of the housing above the mounted radiometer disk. The annular baffles on the side towards the radiation sources are coated as a black body so as to increase the thermal coupling of the black body housing to the ambient being radiometically observed.

Abstract: A method is provided for quantitatively monitoring the deprotection and coupling reactions employed in the solid phase synthesis of peptides. The method entails synthesizing a peptide on a support matrix that has a first marker associated therewith. The amino acids employed in the peptide synthesis procedure have a second marker attached thereto, which can be the blocking group used for the amino acid. After the coupling or deprotection step a portion of the support matrix is processed to release first and second identifers from the first and second markers, respectively. The completeness of the coupling or deprotection step can be determined by comparing the relative amounts of the detected first and second identifiers. Novel compositions of matter are used in or produced during this method, including support matrixes having pyrolyzable markers attached thereto.

Abstract: A method of validating measurement of a kinetic chemical reaction comprises a first tier of validation to validate the ability of a measurement and detection system to provide accurate data, a second tier of validation to validate the initiation and control of the kinetic chemical reaction and a third tier of validation which verifies first that the expected kinetic chemical reaction has proceeded in a characteristic manner and direction, and second, that parameters of the chemical reaction are within limitations characteristic of the measurement and detection system of a measuring instrument investigating the reaction.

Abstract: A record of calibration data containing determined values required for accurate operation of a scientific instrument measuring transmissions or absorbance of light in analysis is provided. A method of maintaining and using the records generated by the instrument permits use of the instrument to determine which records are required for efficient and easy instrument usage.

Abstract: A composite material rotor is disclosed which is made from a plurality of stacked and bonded epoxied filament wound discs, each disc providing a specially wound construction so that the modulus of the rotor body may be varied in proportion to the maximum stress encountered by the rotor during ultracentrifugation. Such a layered disc assembly allows the rotor to be fine-tuned to respond to a variety of stress encountered during ultracentrifugation. Where upper hoop stress is greater, upper disc 28 might be wound using a higher modulus filament fiber than the fiber used by disc 26.

Abstract: Apparatus for sensing liquid levels in fluid transfer mechanisms and the like comprises a conductive member supporting containers for sample liquids, the conductive member being rotatably mounted for positioning selected containers under a conductive pipette probe. A low-frequency oscillator is capacitively coupled to the conductive member for generating an alternating electric field and producing an electrical signal at the probe. As the probe is lowered toward the liquid, an amplifier circuit monitors an electrical signal received by the probe. When the probe contacts the liquid, the amplifier detects a signal level in excess of a threshold level and produces an output signal for inhibiting the downward movement of the probe at the moment of contact with the liquid.

Abstract: A reagent of the type comprising an acid, a molybdate salt, a non-ionic surfactant, and polyvinylpyrrolidone (PVP). The reagent is characterized in that it further comprises an enhancing amount of at least one sugar alcohol. Also, a method for assaying inorganic phosphorus of the type which comprises mixing a sample of biological fluid with a reagent and measuring the absorbance of the resulting solution. The method is characterized in that the above reagent is employed therein. The method can further be characterized in that the measurement can be made via a rate technique.

Abstract: An improved mirror alignment control for dynamically aligning the reflecting mirrors bounding the optical path in an interferometer comprises a closed loop servo control which utilizes a two frequency laser beam to provide phase comparison between beams traversing differing portions of the optical paths in the interferometer to determine alignment of the mirrors, said phase comparison providing a correction signal to direct multi-axial alignment of at least one of the mirrors.

Abstract: A centrifuge overspeed protection and imbalance detection system is structured to provide a method for detecting rotor imbalance and rotor overspeed. The system has a single transducer to provide real-time data necessary to detect rotor imbalance and control motor speed.Motor speed is controlled by synthesis of a drive frequency signal for driving the inverter motor control. The drive frequency signal may be inhibited to provide slow acceleration or deceleration, or to shut the motor off by providing a zero slip frequency. Motor control is responsive to a Rotor Identification circuit and operator programming, as well as a closed loop response to the real time tach signal.Imbalance detection is provided by counting tach pulses in each of a plurality of intervals, detecting deviations in tach pulse rate and sounding an alarm when the irregularity of tach pulse signals exceeds the limits of a predetermined standard deviation.

Abstract: An electrophoretic gel which, when used in an electrophoretic process for the separating chylomicrons, beta lipoproteins, pre-beta lipoproteins, and alpha lipoproteins, enables the separation of the alpha lipoprotein band from the faster moving free fatty acid albumin band. The electrophoretic gel comprises a matrix selected from the group consisting of polysaccharides and derivatives thereof, a buffer having a buffering capacity in an alkaline pH range, and an effective amount of a poly(oxyethylene)-poly(oxypropylene)-poly(oxyethylene) block copolymer.An improved electrophoretic technique characterized in that the above electrophoretic gel is employed therein.

Abstract: A random access rotary pinch valve for controlling fluid flow through a plurality of fluid conduits. The valve is adapted to receive and retain the fluid conduits and includes, for each of the conduits, a toggle mechanism comprising a piston and a toggle. The piston and toggle can be latched to pinch the associated fluid conduit to a non-conducting state or may be latched with the conduit in a fluid conducting state. An actuator arm is selectively positioned over the toggle mechanisms and is displaced so as to actuate the toggles from one state to another, thus changing the state of fluid conduction through the associated flexible conduit. In the embodiment disclosed herein, the fluid conduits are arranged about the periphery of an annular valve body and the actuator arm is pivoted by means of the stepper motor over the toggle mechanisms.

Abstract: A method and apparatus for indicating quench associated with a liquid scintillation solution wherein the solution includes a sample, a solvent and a solute. The method includes exposing the solution to flashes of light, detecting a pulse height spectrum for scintillations produced in the solution in response to the light flashes, determining a unique point on such pulse height spectrum, and relating the unique point to a corresponding pulse height value, such pulse height value providing an indication of quench associated with the solution. The wavelength of light preferably excites essentially only the solvent and the light flash intensity and duration is such that the pulse height spectrum produced in response to the light flashes does not overlap a pulse height spectrum for the sample in the solution. An attribute of the shape of the light pulse height spectrum may be examined to provide an indication of the homogeneous or non-homogeneous nature of the quench present in the solution.

Abstract: A centrifuge adapter is formed in two sections divided by a plane that preferably extends through the longitudinal axis of the adapter. The two sections may be substantially identical in a first embodiment, each including a generally semicylindrical portion having a trough therein and further including an end portion. In a second embodiment, the adapter may comprise a first section including the entire bottom end portion for supporting the bottom of a centrifuge tube. The second section is formed generally as a semicylinder. When the first and second portions are assembled in facing relationship the troughs form a cavity for receiving a centrifuge tube therein. The sections of the adapter may be separate pieces, or they may hingedly connected along a pair of adajcent edges. The sections may be connected by projections extending from one section into corresponding cavities in the other section.

Abstract: A mixing valve includes a housing having inlet ports and an outlet port that intersect at a valve chamber. A valve core within the valve chamber includes passages in fluid communication with the inlet and outlet ports. The passages intersect at a cavity within the valve core. An elastomeric seal retained within the cavity sealingly engages the valve core around the passages in the absence of fluid pressure in the inlets. Injection of a pressurized fluid in one of the inlets causes the seal to move away from both the corresponding inlet passage to permit fluid flow from the pressurized inlet port to the outlet port and compresses the seal around the other inlet port to provide a tighter seal than existed before application of pressure to the first port.

Abstract: A slotted retaining plate for use in a tubular reactor within an analytical system. The reactor contains inert packed material which provides for the necessary flow path length for a fluid stream entering the reactor. The retaining plate is extremely thin and has an array of slots which permit the necessary flow of the stream through the reactor, but retain the packing material within the reactor. The design of the slot array in the retaining plates essentially eliminates any possible impediment to the stream flow. The slots are adjustable to provide more flexibility in slot size control to allow use of smaller packing particles within the reactor and improve the instrument resolution in, for example, an amino acid analyzer.

Abstract: In a liquid scintillation counter, a standard radioactive source is supported in a bead position of a bead chain, flexible conveyor. The conveyor is guided for movement along a closed-loop conveyor path in sliding engagement within a conduit guideway for conveying the source between an operating position adjacent the counting chamber and a remote shielded position. The conveyor may support one or more sources for conveyance to one or more counting chambers along the conveyor path.