Abstract: A centrifuge rotor having a sealing element which automatically controls in response to the centrifugation operation the fluid communication between separate fluid mixture chambers within the rotor. The sealing element is situated within the rotor above an annular and an inner chamber used for containing a fluid mixture. When the rotor is assembled and stationary, the sealing element establishes a seal between the respective chambers. During the rotation of the rotor in a centrifuge, the centrifugally induced pressure exerted by the fluid mixture moves the sealing element, releasing the seal between the respective chambers and allowing fluid communication between the chambers. As the rotor returns to a stationary position and the centrifugally induced pressure of the fluid mixture subsides, the sealing element automatically re-establishes the seal between the respective chambers.

Abstract: In a table top centrifuge of the type including a rotor and a housing defining a chamber for the rotor, the housing having a removable cover therefor, there is disclosed an improvement wherein the cover has first and second passageways extending entirely therethrough, from the center and periphery, respectively, thereof to spaced locations on one of the outer surfaces thereof to define inlet and outlet ports, respectively. A refrigeration unit is provided having a cold air outlet port and a warm air inlet port at spaced locations on one of the outer surfaces thereof, the spacing between and orientation of the centrifuge and refrigeration unit inlet and outlet ports being such that positioning of the one outer surfaces of the centrifuge and refrigeration units in contact with each other aligns the outlet and inlet ports of the refrigeration unit with the inlet and outlet ports, respectively, of the centrifuge.

Abstract: A method and apparatus for inhibiting measurement of nuclear radiation in a scintillation counter during periods of excessive background radioactivity produced, for example, by cosmic energy surges impinging on the scintillation counter. The count rate of a radioactive source or sample being measured is monitored and detector means are provided for detecting the occurrence of an energy surge exceeding a predetermined energy level. When a surge is detected, inhibit means inhibits counting for a time period which varies inversely with the count rate.

Abstract: A portable, automated chemical analyzer having a polarographic oxygen electrode submerged in a batch of stirred solution. The signal from the electrode is directly differentiated and amplified to produce a signal proportional to the time rate of change of oxygen concentration. The membrane of the polarographic sensor is stretched very tightly over the cathode surface to provide a high signal-to-noise ratio. Methods for analyzing cholesterol-cholesterol oxidase and various other enzyme systems by the polarographic electrode oxygen sensing apparatus include the steps of converting the sensed signal into time rate of change of oxygen concentration and recording the maximum rate of change of oxygen concentration.

Abstract: This invention provides a snap-in terminal for electrical connection between an external conductor and a conductive film deposited on a nonconductive substrate. The terminal is stamped from a flat sheet of resilient conductive material and comprises a center position having a forward extension to which the external conductor may be attached and a rearward extension curved downward for establishing electrical contact with the film on the substrate, and a plurality of legs extending outward from the center portion and bent about 90.degree. downward from the center portion, each leg having at its terminus a tab. The terminal is installed by inserting the legs into a slot in the substrate contiguous with the film. The tabs deflect to fit within the restricted space of the slot and then recover their original position as they emerge from the slot at the bottom of the substrate, thereby securing the terminal to the substrate.

Abstract: A kinetic assay is provided for measuring alpha-amylase content in aqueous solutions. The assay is based on the following reactions:alpha-1,4 linked glucan .sup.alpha-amylase alpha-maltosealpha-maltose + PO.sub.4 .sup.-.sup.-.sup.- .sup.MP Glucose + beta-D-G-1-Pbeta-D-G-1-P .sup.beta-PGM G-6-PG-6-P + NAD .sup.G6PDH 6-P-G + NADHthe concentration of alpha-amylase is determined by measuring the rate of increase in absorbance associated with the production of NADH which is a measure of the activity of alpha-amylase.A novel reagent system is used with the assay and comprises:A polysaccharide having glucose molecules primarily connected through alpha 1,4 linkageMaltose phosphorylase (MP)Phosphate ions (PO.sub.4 .sup.-.sup.-.sup.

Abstract: An improved apparatus and method for braking the rotation of a centrifuge rotor is disclosed comprising magnet means operable in a first position wherein substantially no eddy currents are induced in a rotating rotor made of electrically conductive material by the magnetic flux of the magnet means and a second position wherein eddy currents are induced into the rotating rotor sufficiently to slow the rotor. In the preferred embodiment, the magnet means is movable by fluid pressure from the second position to the first position and movable by a bias force from the first position to the second position.

Abstract: An improvement to a misfire monitor sensing lean-roll in an internal combustion engine by comparing the rate of change in O.sub.2 in the exhaust gases with respect to time against a limit is disclosed. In the preferred embodiment, the sensed O.sub.2 level in the exhaust is used as an input to rescaling means which automatically normalizes the values used in the comparison to a standard range. Normalization is accomplished alternately by rescaling the rate of change value, rescaling the limit value used, or diluting the exhaust gases sampled to the level of a "standard" air blown engine to which the comparison limit is scaled.

Abstract: An adjustable supporting arrangement used within the sample receiving cavity of a centrifuge rotor to hold and align a plurality of test tubes. The arragement is comprised of a series of similarly configured interface layers which can be variably arranged to accommodate different sized test tubes. A bracket member is utilized to retain the alignment of the various interface layers and hold them as a single unit for convenient movement into and out of the rotor cavity. Incorporated within the supporting arrangement is a separate cushion pad to receive the bottom ends of the test tubes. A uniquely designed divider plate can be placed within the supporting arrangement to partition the rotor cavity into two areas for receipt of two sets of test tubes in stacked relation.

Abstract: An adaptor for use in a centrifuge bucket for evenly distributing a number of cylindrical test tubes thereacross and for maximizing the number of test tubes positionable in the bucket. The adaptor comprises a thin, flat, disc-shaped plate having a diameter approximately equal to the inside diameter of the bucket and a plurality of separate, unconnected partitions made integral with and extending normal to one side of the plate, the partitions defining a plurality of cavities for receipt of the bases of the test tubes. The partitions support substantially less than the entire circumference of each tube and have lengths which are substantially less than the lengths of the tubes. A lifting tray and handle provide means for lifting the adaptor and test tubes from the rotor bucket.

Abstract: A fluorometer for analyzing a sample by detecting light induced radiation emitted from the sample including apparatus for generating a narrow slit of light in the plane of the sample and transfer apparatus including a light shield having an acutely angled port immediately adjacent the sample for collecting radiation emitted by the sample and transmitting same via a light pipe to a remote detector.

Abstract: Exhaust gas diagnostic apparatus capable of use on both catalytic converter equipped and non-catalytic converter equipped motor vehicles is disclosed. A fast response oxygen analyzer is coupled with means for differentiating the signal output of the oxygen analyzer. In this manner, both the quantity and rate of change of oxygen in the exhaust gas is made available to apparatus included therein for indicating and/or alarming quantity and rate of change values outside preset limits. The apparatus is particularly directed to the detection of an engine misfire condition. The apparatus disclosed permits diagnosing problems without disconnecting the air injector system (if present) or having a port prior to the catalytic converter. As it alarms on transients, it is independent of the steady state oxygen level.

Abstract: A method is provided for automatically compensating liquid scintillation systems for efficiently counting samples of varying quench by establishing the amount of change of a system parameter such as gain required to restore the sample spectrum to be counted in at least one counting window to the proper counting window discriminator levels as a non-linear function of the change in a measure of quench. The degree of quench may be measured on each of the samples prior to counting, for instance by the external-standard channels-ratio method, and the system parameter automatically adjusted to restore the spectrum to the proper window or windows. Implementing circuitry shown includes a digital-to-analog converter and non-linear network which can be calibrated by using the endpoint of a known least quenched sample to establish the base gain and a reference standard and using a known, highly quenched sample to establish another point on the gain vs.

Abstract: An arrangement for the controlled delivery of liquid reagent is shown wherein a reservoir vessel for storing the liquid in volume is coupled to replenish a "vestibule vessel" provided for intermediate storage of the liquid enroute to the delivery point and for pneumatic propulsion thereof, the liquid being pneumatically driven from reservoir to the vestibule through a unidirectional check valve.

Abstract: Detector apparatus for a laser light scattering photometer of the type for measuring radiant power scattered from a sample at a selectable angle with respect to the direction of an incident beam of radiant power and for measuring radiant power transmitted through the sample in the direction of the incident beam. The improved detector apparatus receives and detects the scattered power and the transmitted power and provides an output indicative of the radiant power of each independent of the spatial properties of the two beams. The detector apparatus comprises a planar diffuser spaced from and parallel to the large area end-window of a photomultiplier detector, the diffuser diffusing the energy over the surface of the end-window. The diffuser and photomultiplier detector are positioned within a cylindrical container which is enclosed at the end thereof in front of the diffuser, the enclosed end of the container having an aperture therein through which the beams pass to the diffuser.

Abstract: A semiconductor material is doped or alloyed under vacuum with an impurity by thermal decomposition and by sedimentation resulting from centrifugal force. The doping material is alternatively applied by evaporation before being subjected to centrifugal force and may be heated up to the melting point before completion of the centrifugal action. A centrifuge is provided having a thermal insulating layer between the outer wall of a rotor and a support for basic semiconductor material to be doped. The doping impurity material to be evaporated onto the basic solid state material is placed in the center of the centrifuge rotor.

Abstract: An amplifier capable of operation in four modes singly or in combinations is disclosed. The modes are: DC amplification mode, AC amplification mode, suppressed baseline mode, and offset correction mode. In the DC amplification mode, the amplifier operates as a conventional DC amplifier. In the suppressed baseline mode, the outputs of the input and output amplifiers are connected back to their input stages through a long time constant integrator resulting in the suppression of any DC output voltage. In the AC amplification mode an RC decoupling network is inserted in the inputs to the input amplifier means to pass AC signals and reject DC components. In the offset correction mode, the inputs of the input and isolator amplifier means are shorted to create zero differential at the summing junctions thereof. Any offset voltage present at the output of the input amplifier means or output amplifier means is suppressed by means of integrated feedback to the input stage of the input and output amplifier means.

Abstract: A set point adjust mechanism is disclosed for use with process controllers to manually adjust the set point value and simultaneously change the set point value indicated. The set point adjust mechanism includes a manually actuable thumbwheel and an idler wheel mounted in contact with each other on a slider. Thumb pressure on the thumbwheel causes the slider to move so that the idler wheel contacts an indicator drive wheel. The set point value source, usually a potentiometer, is connected to the indicator drive wheel which also drives a belt that positions a pointer with respect to a scale. The pointer and scale provide the set point indication. When the pointer hits a pointer stop, or for any other reason resists motion, further rotation of the thumbwheel causes the idler wheel to move to engage a mechanical stop to prevent further thumb pressure from causing dislocation between the indicated set point value and the set point value source.

Abstract: Improved apparatus for bringing a fluid in a process stream in contact with a sensor is disclosed. The present invention uses the kinetic energy of the process fluid to convey some of the fluid to and from the sensor, as opposed to the prior art practice of inserting the sensor itself into the process fluid stream. A nozzle is placed into the process fluid stream facing into the direction of flow. A small portion of the flowing process fluid is trapped by the nozzle and some of its kinetic energy is converted to pressure. This pressure causes a flow from the nozzle into a conduit through an open valve to the sensor. The fluid continues past the sensor and returns to the process fluid stream through the same valve. In one embodiment, the path for incoming fluid and exiting fluid are separate paths. In a second embodiment, the incoming fluid and exiting fluid exist coaxially.

Abstract: A method for determining the source strength of a radioactive sample such as iodine-125 or cobalt-60, which emit pairs of quanta of radiation in coincidence, or near coincidence, and for determining the counting efficiency of a detection instrument analyzing such samples. A first counting channel is used to count events attributable to single quanta, a second counting channel is used to count events attributable to coincident pairs of quanta, and the sample source strength is computed from the results of measurement in these two counting channels. Then, the counting efficiency in a third channel designed for subsequent use in analyzing test samples may be determined from the counting of events in the third channel.