Abstract: An array of reaction tube covers adapted to seal a plurality of reaction tubes comprises a unitary body of flexible material having a plurality of flexible plastic nodules. Each nodule is adapted to seal one of the reaction tubes. Each of the nodules is flexible held in a predetermined planar spaced relationship from each other in rows, preferably in rows and columns, by an integral web having a plurality of apertures therethrough. Each of the nodules has a downwardly convex, generally hemispherical lower portion extending from the web, an upwardly convex upper portion extending from the web over the lower portion, and a centrally domed nipple extending upwardly from the upper portion.

Abstract: In an angular gas cap on a wire thermal spray gun, a forward channel extends from a rearward channel at an oblique angle thereto so as to have a lateral directional component. The rearward channel at the nozzle has a channel axis parallel to the central axis of the nozzle and is offset from the central axis in a direction opposite the lateral directional component. Immediately upon termination of spraying the wire is retracted into the nozzle. A wire positioner includes a hollow collet with the wire extending therethrough. A linear actuator retains the collet against a wall to hold the collet open from the wire during spraying. Upon termination of spraying the actuator retracts to release the collet from the wall so the collet is sprung to engage the wire during the retraction. Upon startup the wire is advanced into the gas cap faster than normal spraying speed.

Abstract: A Wheatstone bridge type thermal conductivity sample gas detector. A sensing element comprising one arm of the bridge is disposed in a constant temperature oven. A variable resistor, which functions as a reference element, and two fixed resistances comprise the second, third, and fourth arms of the bridge. Carrier gas is circulated around the sensing element and the bridge is balanced by use of the variable resistor. Thereafter, any unbalance of the bridge is caused by sample gas intermingling with the carrier gas, thereby providing a signal representation of the sample.

Abstract: A wire flame spray apparatus includes a wire feed pulley driven by a motor. A first counterpulley urges a wire into engagement with the feed pulley. A detector pulley with a second counterpulley engages the wire to detect actual wire feed rate. A balance beam supports the counterpulleys. A pressure cylinder acts on the beam to increase counterpulley force on the wire in response to a lagging of actual feed rate from a predetermined feed rate so as to avert slippage of the wire on the feed pulley. A sensor senses changes in rotational speed of the detector pulley and generates signals to increase the counterpulley force. A microprocessor provides control signals for the motor and pressure cylinder.

Abstract: To calibrate a photodetector, a rotating disk with a slot is disposed in a light beam with decreasing speed from a defined maximum rotational speed to a defined minimum speed, while magnitudes and times of signals are read out and stored. Vernier pairs of signals occur in adjacent readout intervals, and non-vernier signals exclude the verniers. Readout times for verniers are used to estimate a preliminary function of rotations versus time. From the function are estimated an occurrence time for each pair and period of disk rotation at the time. Vernier fraction is the ratio of one signal in the pair to the sum of the pair. A time offset is the product of vernier fraction, slot fraction of the disk and the estimated period. Occurrence times corrected with the time offset are utilized to fit a corrected function of disk rotations versus time. Points of time for the non-vernier signals are determined from the corrected function, each point corresponding to disk rotations to a corresponding non-vernier signal.

Abstract: Apparatus for verifying the temperature of a polymerase chain reaction system comprises a pair of conical probe tips which are shaped to fit the wells of the temperature-controlled sample block. One of the probe tips encloses a resistance thermometer device which is connected by cable to a meter outside the system. The cable passes through the other probe tip where it is warmed, thereby reducing measurement errors due to heat conductance to ambient. The probe tips are normally arranged to fit into adjacent wells of the sample block.

Abstract: A high impedance current source includes a voltage to current transducer having positive and negative inputs with an output current passed through a monitor resistor. Matched resistances are connected from both sides of the monitor resistor back to the positive and negative inputs to the transducer. Matched resistances are also connected between the positive and negative inputs and a common base, and the control voltage is applied across the inputs through matched resistances. The circuit is preferably utilized to provide current to a circuit utilized in differential calorimetry.

Abstract: In an electrode assembly, an electrode holder has a forward end thereof affixed coaxially to an electrode tip. An attachment member is affixed to the holder rearwardly of the electrode. A retaining assembly includes an outer cup component, an inner cup component and a magnet therein. An electrical lead is connected to the inner cup component. The electrode assembly fits coaxially into the retaining assembly with the attachment member adjacent to and retained by the magnet. The electrode holder is seated in electrical contact with the inner cup component. The holder, cup components and attachment member are magnetically permeable, and separated in each assembly by insulators, so as to effect an outer magnetic shielding loop and an inner magnetic shielding loop.

Abstract: The sun's energy is used in combination of movable and fixed diffuser plates, windows and apertures which are positioned in a series of test sequences (modes) for reflectance monitoring and calibration without the use of man-made sources. There are three embodiments, or implementations, of the invention--one embodiment uses two diffusers--a working diffuser and a secondary diffuser--the second embodiment uses three diffusers, a working diffuser, a secondary diffuser and a reference diffuser--and the third embodiment uses two diffusers--a working diffuser and a secondary diffuser, the latter also functioning as a cover for the working diffuser. The movable diffusers are mounted on rotatable cones and, in all embodiments, the sun is blocked from reaching the diffusers when not in use.

Abstract: A method for determining concentrations by means of atomic emission spectroscopy which contains the method steps: (a) generating an atomic emission with a known concentration of a looked-for element, (b) scanning the obtained emission spectrum by means of a spectral photometer with a spectral slit width in a wavelength range which contains a spectral line of the looked-for element, (c) generating an atomic emission with an unknown sample which contains the looked-for element with the concentration of the looked-for element in the unknown sample to be determined, (d) scanning the obtained emission spectrum by means of the spectral photometer with the same spectral slit width and in the same wavelength range in which the scanning of the emission spectrum with the known concentration was made, (e) processing the spectral-representing signal, which is provided by the spectral photometer independent of the wavelength by means of a recursive Kalman filter, in order to generate an estimate for the concentration of t

Abstract: An optical transmittance apparatus has a pair of reference channels of glass rods and a pair of sample channels containing sample fluid. A beam splitter and mirror pass a first portion of an incident beam through an ingoing reference channel, and a second portion through an ingoing sample channel. The first portion is reflected back through an outgoing reference channel, and the second portion back through an outgoing sample channel. The beam splitter and mirror directs the outgoing beams into a common outlet path. A partial disk selectively passes either portion. For positioning the disk, poles of a magnet mounted on the disk axle face windings made about an axis perpendicular to the axle, the windings being on the opposite side of a barrier plate from the poles. Current of one polarity through the windings effects one orientation of the disk, and reversed olarity reorients it perpendicularly.

Abstract: Alkali metal-containing glass beads for use as sources in thermionic detectors for gas chromatography are manufactured by a method which produces reproducible beads of preselected sizes. A glass tube of the desired composition is reduced to capillary size. A section having the volume of the desired bead is cut from the capillary tube and threaded onto a support wire. It is then melted and caused to coalesce onto the support wire. The resultant bead and a portion of the support wire are then incorporated into the detector.

Abstract: A mobile component carrier in an instrument includes a disk with a scalloped periphery. A larger bearing and a smaller bearing are mounted on a support structure. The larger bearing has a radius greater, and the smaller bearing has a radius less than that of each of the scallops. The disk is urged into the bearings which have a relative spacing such that the larger bearing seats against two adjacent intersections of the scallops, and the smaller bearing seats against a dished surface between two other adjacent intersections.

Abstract: A double beam detector system for liquid chromatography includes a light source and slits to effect two beams of radiation symmetrical to an optical axis and focused through a common point. A concave reflective dispersion grating is disposed on the optical axis which is folded at the grating. A collimating lens directs the beams parallel to the optical axis into a pair of detector cells. The collimating lens and entrance lenses for the cells are selected so that the common point is imaged on exit windows of the cells. The grating has a curvature selected cooperatively with the collimating lens, entrance lenses and relevant distances so as to focus the entrance slits at respective entrance windows for the cells. The beam size is constricted to less than the cell bore size by selected parameters of the collimating lens and the entrance lenses.

Abstract: An analytical instrument sample vial positioning and sensor device. A radius or cone-shaped body portion extending below a surface contacts a loosely held sample vial having a flexible septum thereon. The shaped body portion is biased downward resulting in the relative movement between the sample vial and shaped body portion tending to center the flexible septum under the shaped body. A longitudinal bore extending through the shaped body permits the insertion of a syringe needle for the removal of a sample to be analyzed. The pre-positioning of the sample vial presents syringe needles from being bent or broken due to inappropriate alignment with respect to the septum. A sensor is incorporated with the shaped body to detect the presence or absence of a sample vial.

Abstract: A precision bridge measurement circuit connected to a current source providing a linear output voltage versus resistance change of a variable resistance (resistance temperature transducer) including a voltage follower in one branch of the bridge so that the zero setting of the transducer resistance does not depend upon the current source or upon an excitation voltage. The zero setting depends only on the precision and stability of the three resistances. By connecting the output of an instrumentation amplifier to a feedback resistor and then to the output of the voltage follower, minor nonlinearities in the resistance-vs-temperature output of a resistance-temperature transducer, such as a platinum temperature sensor, may be corrected. Sensors which have nonlinearity opposite in polarity to platinum, such as nickel-iron sensors, may be linearized by inserting an inverting amplifier into the feedback loop.

Abstract: A high velocity thermal spray gun includes a nozzle member injecting an annular flow of combustible mixture at high pressure into a constricted gas cap. An outer flow of air is injected adjacent to the gas cap wall. Powder is fed axially from the nozzle member into the combustion chamber. An annular inner flow of air is injected coaxially outwardly of the powder. The nozzle face has a shallow annular slot therein between the outer and inner gas injections. Combustion gas and oxygen flow through separate annular gas channels to mutually impinge at the inlet end of the slot for effectual mixing, so that combusting of the combustible mixture is rooted in the annular slot.

Abstract: A powder pickup device has a tube formed of an elastomeric tube wall with an orifice therein receptive of powder from a vessel so as to direct powder into a carrier gas in a central passage in the tube. A tubular shell supports the tube and has an aperture therein aligned with the orifice. In another embodiment the tube is combined of a rigid tube and an elastomeric tube fitted tandemly in the shell. The rigid tube extends to an inner end proximate the aperture and has the orifice situated therein. The elastomeric tube extends from the rigid tube and is disposed so as to place a section thereof opposite the orifice.

Abstract: A superconductive oxide powder is produced by a method comprising spray drying a slip to form agglomerates, feeding the agglomerates sequentially through a first and a second oxygen supported combustion flame for fusing the fine particles in the agglomerates to form an intermediate powder, annealing the intermediate powder in an oxygen-containing environment such as to produce a friable mass, and crushing the mass to form the superconductive oxide powder. For example, a precursor compound in the slip is barrium carbonate, the other precursor constituents are yttrium oxide and copper oxide, and the yttrium, barium and copper in atomic proportions in the precursor constituents are 1:2:3+Y where Y denotes a copper surplus having a value of up to about 1.5. In the final powder the proportions are 1:2:3+Z where Z is between about 0.2 and 1.0.

Abstract: An object mounted on a carrier constitute a rotationally free system such as a telescope on a space vehicle. A separation vector is directed from the center-of-mass of the carrier to the center-of-mass of the object. The object is rotated through a selected angle thereby defining a rotation vector. Simultaneously the object is translated so as to displace the object center-of-mass through a translation distance in a direction such that mathematically crossing the translation vector into the separation vector results in a further vector having the same direction as the rotation vector. A formula is provided for the translation distance in order that the object may be rotated without counter-rotation of the carrier.