Abstract: A flexure, useful as a universal joint between two corotating members, the flexure being capable of flexing about two orthogonal axes, but providing extremely good stiffness with respect to translational forces is accomplished in a flexure in the form of a cross including two members having a cross-shaped cross-section extending along two mutually perpendicular axes, the members terminating at each end in solid pieces with the solid pieces at the end of the one member used for attachment to one of the rotating members and the solid pieces at the ends of the other member for attachment to the second rotating member.

Abstract: A pneumatic nebulizer of the type used for aspirating a fine spray of a liquid analytical sample into the sample burner flame of an atomic absorption spectrophotometer or the like. The nebulizer comprises an atomizing venturi nozzle formed of corrosion-resistant material, the nozzle including a monolithic flexible tube having one end extending to a sample source and its other end terminating coaxially within an apertured nozzle member to define therewith an annular orifice through which high velocity gas flow occurs to aspirate sample liquid from the other end of the tube.

Abstract: A seal between the opposing surfaces of two joined members, wherein at least one of the surfaces is disposed about a bore or cavity. A salient portion (edge or bead) is formed on at least one of the surfaces and around the bore or cavity, and a gasket of resilient material is disposed between the surfaces to overlay the salient portion. The portions of the opposing surfaces other than the salient portion are substantially planar, and the gasket extends across the salient portion. Each salient portion is preferably formed by its opposing surface being disposed at an incline to an apex and the gasket is configured to have a thickness such that some extending portion thereof aside the salient portion is subjected to compression, of lesser degree than that applied by being at the salient portion.

Abstract: A stepping motor control circuit for precisely controlling the motion thereof. The control circuit energizes the motor windings according to the design sequence for rotation in a given direction. Each winding is energized by a signal having an ascending staircase for its leading edge, a descending staircase for its trailing edge and a steady state level between the leading and trailing edges. The ascending staircase and the descending staircase each comprise one quarter of the terms for each winding energizing signal. The steady state level occurs for one half the time of each energizing signal. The total number of steps in all ascending and decending staircases is controlled and selects the total rotation of the motor. When the motor reaches the desired position whether in the middle of a staircase or not, the signals coupled to the stepping motor windings are frozen at the level when the total step count is reached.

Abstract: A cooling vent within a thermal system, which has heat otherwise supplied to regulate the temperature thereof, is controlled to open and close incrementally so that temperature control near room ambient is facilitated.

Abstract: Sample preparation apparatus for forming a thin layer of diluted blood specimen on a substrate by centrifugal force includes a sample probe having coaxial blood and diluent conduits coupled to respective reversibly-drivable peristaltic pumps having forward operation intakes connected to a diluent supply. A one-way clutch limits the diluent pump to forward operation and the pumps are geared to produce a blood-to-diluent displacement ratio of 2:1. A substrate holder is mounted on a carriage for selective insertion into and removal from a sealed centrifuge chamber in which it is spun at a high angular rate by a drive motor. Means are provided to form a curtain of flowing liquid within the chamber surrounding the spinning substrate to collect spun-off blood particles and aerosol. The liquid forming the curtain is drained by an exhaust pump which operates after spinning has ceased so as to create a partial vacuum for draining off residual aerosol prior to unsealing the centrifuge chamber.

Abstract: In an optical system having a mirror system for reflecting light from a field of interest to form a desired image on sensitive material disposed in a focal plane, the improvement characterized by the provision of a centrally located obscuration disposed adjacent the front of a mirror for intercepting light reflected from the sensitive material toward the mirror to prevent reflection from the mirror of said light reflected from the sensitive material from reilluminating the sensitive material, to thereby improve the contrast the desired image.

Abstract: An improved slide holder for use with a clinical spinner comprises a support having a channel defined in the top thereof transverse to the vertical axis of rotation of the support. Rapid rotation of the support with a slide positioned over the channel effects a partial vacuum in the channel which tends to hold the slide tightly against the support. Mechanical stops and spring retainers may also be included to insure retention of the slide on the support. The design of the slide holder minimizes the formation of an aerosol during spinning. A disposable spin-off interception system cooperates with the slide holder's operating characteristics to effectively eliminate aerosol formed.

Abstract: A small diameter transparent visible fluid flow indicator suitable for mounting behind an opening in an instrument panel contains a six-bladed paddle wheel pivoted for rotation by the flow of fluid passing through orifices in the indicator housing. Each of the six blades of the wheel contains a small magnet oppositely polarized from the magnets in the adjacent blades to create alternate magnetic fields that pass through a pickup coil embedded in the housing. The resulting coil voltage is amplified and rectified to control a relay switch. Thus, the liquid flow indicator provides both a visible indication of fluid flow and also controls a switching circuit that may be used as an alarm if the fluid flow stops or varies from some predetermined value.

Abstract: A device for atomizing a sample for so-called flameless atomic absorption spectroscopic measurements of the type in which an electrically conducting hollow tube, into which the sample is introduced as by a central port in the side of the tube, is heated by the passage of current from electrodes contacting the ends of the tube. A protective inert gas is caused to surround the interior and exterior of the tube to exclude air to avoid oxidation of the sample tube which may be graphite. The improvement comprises introducing the protective gas into both ends of the sample tube so that it leaves the interior through the central port from which it may be sucked outside of a surrounding housing. The exterior walls of the sample tube may be provided with protective gas either by means of an auxiliary gas flow or by leading the gas from the bore around the outside of the tube before withdrawing it through the surrounding housing.

Abstract: There is disclosed a flow controller-flow sensor combination especiably suited for gas chromatograph applications wherein a transducer monitors the pressure at the inlet and outlet of a flow restrictor element in the controller thereby to monitor the differential pressure across the restrictor; the differential pressure being proportional to the gas velocity through the flow restrictor element. In one form of the invention, a second flow restrictor element is provided in one input line to the transducer which preferably is of relatively low impedance in order to delay the buildup of the pressure head of the corresponding input of the transducer sensor, thus to enable the pressure at the outlet of the flow restrictor in the controller to buildup gradually so as not to exceed the maximum differential pressure specifications for said transducer.

Abstract: In a double beam, optical-null type infra red spectrophotometer, an optical system including a movable dispersive optical element causes transmission of a spectrum of light in respective beams through an adjustable optical attenuator and through a sample and thence to a sensing circuit. The sensing circuit provides an error voltage having an amplitude proportional to the difference between the intensites of the beams passing through the sample and through the attenuator respectively. The position of the attenuator is adjusted in proportion to the integral of the error voltage to cause a reduction thereof while, in response to the magnitude of the error voltage in excess of a threshold value, there is a reduction in the rate of movement of the dispersive element.

Abstract: Anticipation signals are derived for each peak whenever a differential exists within a closed loop having the electrical output connected to the input thereof and a confirmation signal is derived after each peak at a threshold level of the new slope polarity exceeding the noise level of the electrical output. The amplitude of each peak is stored as a voltage level which follows the electrical output throughout either slope polarity until a peak is reached and this voltage level is continuously compared with the electrical output to derive the slope polarity thresholds. Otherwise, a very particular embodiment is disclosed with which the stored voltage level only relates to either the most significant maximum or minimum peak of the electrical output and the disclosed embodiments are related to instruments which perform spectral analysis.

Abstract: A chromatographic column fitting for connecting the column to a connecting tube, which includes a union having an axial through-bore that includes at both ends thereof: a first portion, a second inwardly tapered portion, and a third cylindrical portion connecting the second portions of both ends; one end of the connecting tube being receivable in one end of the union and one end of the column tube being receivable in the other end of the union so that the end of the two tubes engage in butt-to-butt relationship; and ferrules wedged between the outside surfaces of the tubes and their adjacent second portions of the union, respectively; and in another form thereof the invention provides an outlet column fitting which includes a T-shaped union having an inlet at one end and an outlet at the other end and having an axial through-bore, which includes sequentially from the inlet to the outlet, a first inwardly tapered portion, a second cylindrical portion, a third manifold portion, the union having a side inlet ope

Abstract: A pulse generator for producing two output pulse trains A and B where the total number of pulses in both train A and B over a fixed time period remains a constant. The two pulse trains are derived from a master clock which gates a plurality of cascade connected synchronous decade rate multipliers. A selector is set either statically or dynamically to the value N where N is the number of pulses desired in one pulse train out of every M pulses produced by the master clock. A summing means is coupled to all the multipliers to produce a first intermediate pulse train with N pulses for every M clock pulses. A difference means is coupled to each multiplier and to the master clock to produce a pulse in a second intermediate pulse train every time a clock pulse occurs and a pulse in the first pulse train does not occur. A pulse counter is coupled to each intermediate pulse train output to produce two output pulse trains A and B each having a substantially constant pulse frequency.

Abstract: In a device in which an independent variable is stepped or scanned between a first limit and second limit and in which device there is an error which is a function of the independent variable, error correction is obtained by storing correction values, preferably of an incremental nature, for each of a plurality of steps of the independent variable, establishing a location marker which can be identified as different from the error correction data, moving the location marker so as to always be adjacent the error correction for the current position or step of the independent variable and reading out the error correction at the point of the location marker.

Abstract: A device for absorption of selected radiation wavelengths, such as solar radiation, for producing heat energy, consists essentially of a single film or layer of a mixture of metal particles and a dielectric material which are coated on a supporting substrate of either metal or glass. The metal and dielectric concentration varies in a gradual transition from a major portion, up to 100%, of metal at one boundary surface to a major portion, up to 100%, of dielectric at the opposite boundary surface. There are no interior boundaries in the film; the film composition is inhomogeneous between the boundary surfaces and substantially homogeneous in planes generally parallel to the boundary surfaces. Dielectric materials and metals are disclosed in combinations adapted for solar radiation absorption over a broad band of wavelengths, on the order of from 0.35 to 1.

Abstract: An automatic pipetting system for pipetting a measured micro-quantity of reagent into a reaction cup, in which the pipetter is lowered into a reagent bottle, a predetermined amount of reagent drawn in using a positive displacement pump, the pipetter withdrawn from the reagent bottle through an irrigated wiping sponge to accurately control the drop of reagent at its tip, rotated to a position over the cup and lowered thereinto after which the displacement pump expels a measured amount of reagent.

Abstract: A unity magnification catoptric image-forming system and an illumination system on the one hand, and an object- and image-surface supporting means on the other hand, are arranged for relative movement to retain the object and image surfaces in unity magnification conjugate planes of the catoptric system while effecting a scanning-type exposure of successive portions of the image surface to successively illuminated portions of the object. Fine motion mechanisms permit accurate preliminary adjustment of the object- and image-receiving surfaces relative to each other while under visual examination with the aid of the catoptric image-forming system.

Abstract: Control of test chambers or specimens to stabilized temperatures at set points over a wide temperature range is accomplished with improved response time by an arrangement of cascaded Peltier affect heat pumps. Generally, power to a first Peltier unit in the arrangement is controlled relatively to the temperature deviation of the specimen from the desired set point, while power to a second Peltier unit therein is controlled proportionally to the temperature differential across the first Peltier unit. In applicatons where large thermal losses to ambient occur, a portion of the power control signal to the second Peltier unit is applied to offset the temperature set point as a compensation for such losses. Improvement in approach to stabilized temperature is further attained by applying an anticipation signal in proportion to the temperature gradient between the specimen and the first Peltier unit to decrease the monitored deviation of the specimen temperature from the set point.