Abstract: Apparatus for the analysis of samples such as blood or urine includes a reaction cell for reacting the sample with a chemical reagent at a predetermined temperature. A heat exchanger is provided on the reaction cell for establishing the temperature of the cell. Reagent is pumped into the cell through a conduit, and a portion of the conduit is wound around the reaction cell in contact with the heat exchanger to preheat reagent in the conduit before the reagent is pumped into the cell.

Abstract: A valve construction in the form of a "flex-finger" or flexible stem valve is provided for handling substances which are highly corrosive or very active chemically. The valve body, valve seats, a valve ball and flexible finger or flexible valve stem are all composed of chemically resistant material. The flexible stem has an outer end secured in the valve body against rotation with a fluid tight joint and an inner end for actuating the "ball". The flexible stem is composed of material which is sufficiently resilient so that it may be caused to travel in a circular or orbital path carrying or actuating a "ball" or other attachment into and out of engagement with the valve seat or seats.

Abstract: Nematic liquid crystal compositions for use in displays and in other liquid crystal applications comprising a mixture of a nematic biphenyl liquid crystal material, nematic liquid crystal material other than nematic biphenyl which is incompatible with the nematic biphenyl (e.g. when mixed together, it will form a smectic phase instead of a nematic phase) which is present in a concentration that will render the total mixture with improved electro-optic properties and nematic liquid crystal material other than a nematic biphenyl which is compatible with the nematic biphenyl and present in a concentration sufficient so that the mixture forms a satisfactory nematic phase for use in a field-effect display device. The preferred biphenyl-incompatible constituents are certain ester-type nematic liquid crystals and the biphenyl-compatible constituent are other certain ester-type nematic liquid crystal.

Abstract: An improved method of separating free from bound fractions in a solid phase column immunoassay procedure of the type wherein a solution is contacted with a composite comprising an activated polysaccharide matrix covalently coupled to a primary antibody, wherein the improvements comprise:(a) coupling an .alpha.,.omega.-diaminospacer to said activated polysaccharide matrix via one of said .alpha.,.omega.-diamino-spacer's amino groups thereby forming a derivatized polysaccharide matrix; and(b) covalently coupling said derivatized polysaccharide matrix to an antibody selected from a group consisting of primary and secondary antibodies via a bifunctional coupling agent having a formula ##STR1## WHEREIN N IS AN INTEGER FROM 1 AND 6 AND WHEREIN E IS AN INTEGER FROM 1 TO 2.

Abstract: A method of measuring trace level hydrogen chloride concentration in a gas stream is disclosed. The gas stream containing hydrogen chloride is passed through a heated vitreous carbon catalyst and then mixed with ozone in a point source reaction chamber. The light emitted in the chemical reaction is measured by a sensitive amplifier and the output is displayed on a meter, recorder, or any other suitable device. Apparatus for measuring trace level hydrogen chloride concentration in a gas stream is also disclosed.

Abstract: An in vitro radioimmunoassay procedure for measuring an amount of steroid in a sample wherein a separate serum protein inactivation step is eliminated. The separate protein serum inactivation step is eliminated by employing a solution wherein the solvent comprises from about 0 to about 10% of a water miscible organic solvent and from about 90 to about 100% of a buffer having a pH of from about 3 to about 6.

Abstract: A method of separating free from bound fractions in an immunoassay procedure of the type wherein a solution is contacted with a composite comprising a derivatized polysaccharide matrix covalently coupled to an antibody by a bifunctional coupling agent, wherein the improvement comprises selecting said bifunctional coupling agent from a group comprising ##STR1## WHEREIN N IS AN INTEGER FROM 1 TO 6 AND WHEREIN E IS AN INTEGER FROM 1 TO 2.

Abstract: A method of separating free from bound fractions in an immunoassay procedure of the type wherein a solution is contacted with a composite comprising a finely divided, activated, polysaccharide matrix covalently coupled to a primary antibody, wherein the improvements comprise:(a) coupling an .alpha.,.omega.-diaminospacer to said finely divided, activated, polysaccharide matrix via one of said .alpha.,.omega.-diaminospacers's amino groups thereby forming a finely divided, derivatized, polysaccharide matrix;(b) covalently coupling said finely divided, derivatized, polysaccharide matrix to an antibody selected from a group consisting of primary and secondary antibodies via a bifunctional coupling agent having a formula ##STR1## WHEREIN N IS AN INTEGER FROM 1 AND 6 AND WHEREIN E IS AN INTEGER FROM 1 TO 2; AND(c) using a polysaccharide matrix having an average wet maximum dimension of 1 to 18 .mu..

Abstract: A centrifuge test tube cap assembly for sealing a thin walled test tube used primarily with a vertical tube rotor. The cap assembly is designed for convenient and easy removal from the test tube through the use of internal means which activates the direct sealing and unsealing of the cap with respect to the test tube. The mechanism of the tube cap provides for convenient removal of the cap assembly from the test tube which is necessary in order to insert or remove the liquid to be subjected to centrifugation.

Abstract: An improved apparatus and method for braking the rotation of a centrifuge rotor is disclosed comprising magnet means operable in a first condition 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 condition wherein eddy currents are induced into the rotating rotor sufficiently to slow the rotor. In one embodiment, magnet means is movable from a first position wherein substantially no eddy currents are induced in an electrically conductive portion of the rotating rotor by the magnetic flux to a second position wherein eddy currents are induced into the rotating rotor in a quantity sufficient to slow the rotor.

Abstract: Method and apparatus for improved detection of sulfur dioxide by fluorescence are disclosed wherein the effects of interferent hydrocarbons in the test sample are eliminated. In apparatus detecting sulfur dioxide by detecting the fluorescence of sulfur dioxide from narrow band ultraviolet radiation by photomultiplier means, the test sample being fed to the fluorescence chamber is first passed through a reactor to oxidize the hydrocarbons from the sample. The effect of this oxidization is to convert interfering hydrocarbon components in the sample gas into non-interfering materials. In one embodiment employing ozone, moisture removal apparatus is added prior to the oxidization reaction to prevent the error producing formation of H.sub.2 SO.sub.4.

Abstract: A control element for sensing the motion of a movable member within a machine to automatically prevent opening of a cover or guard on the machine when the member is moving. The control element has one of its ends brought into contact with a portion of the movable member and its other end connected to a latching mechanism located adjacent the machine cover. Being an elongated flexible member, the control element moves in response to the movement of the movable member. When the member is stationary, the end of the control element in contact with the movable member causes the control element to become an elongated rigid member to permit the latching mechanism to turn and allow the opening of the cover over the movable member.

Abstract: A test tube cap assembly for centrifuge rotor tubes. A stem member slidably moves within a crown member to exert a direct force on a bushing to securely grip the upper portion of a test tube located within the crown member. The stem member and the bushing have generally mating frustoconical surfaces to provide a wedging action on the upper portion of the test tube. The wedging action serves to not only seal the tube, but also support the upper end of the test tube by restraining the centipetal side of the tube from pulling away from the cap. The operation of the cap assembly is enhanced by the hydraulic forces exerted from within the test tube by the contained liquid.

Abstract: A variable resistor with a dual ratio input shaft that permits rapid and precise adjustment of the voltage or current level in an electric circuit. A single shaft operates the respective drive elements in the mechanism to provide variable control from a single control knob. The shaft is longitudinally slidable between two drive positions. One drive position allows more rapid adjustment of the resistance value for each turn of the control knob than the other drive position which permits more precise adjustment of the resistance value for each comparable turn of the control knob.

Abstract: Method and apparatus for measuring the degree of quench in a liquid scintillation sample by irradiating the sample with a standard source, such as a cesium-137 gamma source, to produce a Compton scattered electron distribution exhibiting a Compton edge configuration as the leading edge thereof. For increasing the quench levels in the sample, the Compton edge shifts to lower pulse height values and the extent of this shift is indicative of the degree of quench. To measure the degree of quench, a unique point on the Compton edge, namely the point at which the second derivative of the edge is zero (i.e. the inflection point), is measured for the quenched sample and the pulse height value corresponding to the inflection point is determined. The pulse height value is compared with the pulse height value determined for a calibration standard in a similar manner, the difference in pulse height values indicating the degree of quench.

Abstract: A variable chart format system for a recorder with a chart print out, the system having a manually selectable switch for simultaneously controlling the abscissa and ordinate formatting independent of scale expansion circuitry normally associated with the abscissa and ordinate. The abscissa formatting is digital and operable in response to a programmable or variable clock, the output of which is selectively passed through a first set of abscissa formatting frequency dividers and then serially through one of a second set of abscissa scale expansion frequency dividers to drive a chart drive stepper motor.

Abstract: A method for the reliable determination of a random coincidence count attributable to chance coincidences of single-photon events which are each detected in only a single detector of a scintillation counter utilizing two detectors in a coincidence counting technique. The method includes the steps of measuring a coincidence count rate as indicated by essentially coincident output pulses from the detectors, measuring a single photon count rate as indicated by output pulses from both of the detectors, whether coincident or not, and determining a random coincidence count rate from the difference between the single photon count rate and the measured coincidence count rate. From the random coincidence count rate thus determined, a percentage error value can be determined, for application, if desired, to subsequently or concurrently measured sample radiation counts.

Abstract: Disclosed herein are powder compositions useful for making conductors, e.g., microcircuit conductors, end terminations for capacitors, electrodes for gas discharge display devices, etc. The compositions comprise inorganic powders dispersed in an inert vehicle and are printed and fired in the conventional manner on dielectric substrates. The inorganic powders comprise a mixture of nickel and/or aluminum or copper and boron. Glass powder and/or silicon powder may also be present.

Abstract: Derivatives of steroids containing an imidazole group specifically bind to the desired antibody without nonspecifically binding to other substances (e.g., proteins in a patient's plasma or serum and the surfaces of reaction vessels).

Abstract: An improved cathode assembly for a gas discharge display panel is disclosed providing a first series of cathode elements in a first direction and a second series of cathode elements in a second direction. A separate "keep-alive" element and "initiate signal" element are also provided. The keep-alive element maintains a localized source of ionized gas at all times. Upon activation of the initiate signal element, the ionized gas moves from the keep-alive element to the initiate signal element. The first direction elements are then sequentially activated to cause the ionized gas to pass from the initiate signal element sequentially to each of the first direction elements until the selected first direction element has been reached. The second direction elements are then sequentially activated to cause the ionized gas to pass from the selected first direction cathode element to the second direction cathode elements in sequence until the selected second direction element has been reached.