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.

Abstract: A method and means for stabilizing the difference in frequencies between the frequency components of a two frequency laser beam influenced by Zeeman effect frequency splitting, accurately determines the frequency separation independently of the individual frequencies or intensities of either of the frequency components. Frequency stabilization is accomplished by mechanical and thermal adjustments to the lasing chamber length of the laser by a closed loop servo control referencing the frequency difference between laser beam components and a reference signal having a frequency equal to the desired frequency difference.

Abstract: A centrifuge rotor is presented having a pivotal mount for a sample container upwardly offset from the radial plane of maximal strength of the rotor permitting a smaller diameter rotor container assembly and reducing exposed surface area of the rotor container assembly.

Abstract: An improved mirror scan control for driving a movable mirror in an interferometer with a constant scan velocity comprises a closed loop servo control which provides constant velocity mirror scan in response to a phase comparison of a signal derived from the beat frequency of a two frequency laser beam passing through the interferometer and a selected frequency reference signal, wherein the difference in frequencies or beat frequency of the two frequency laser beam is stabilized at a specified difference in frequencies. The mirror scan control employs a phase lock control loop which locks the frequency of the referenced signal with the frequency of the signal derived from the laser beam to provide precise mirror velocity control.

Abstract: A liquid flow monitor. The device includes a thermistor placed in the path of liquid flow. A circuit including the thermistor in a Wheatstone bridge is used to sense the liquid flow by sensing the change in resistance of the thermistor. A transistor connected to the bridge is used to maintain the thermistor within predetermined levels to prevent overheating of the device.

Abstract: An improved electrode assembly for use in amperometric gas sensors. A portion of the interior of the electrode assembly that is adjacent to the electrode is filled with an electrochemically inert water-repellant fluid. Once the fluid is in place, a fluid barrier is inserted to cover the fluid and to serve as a foundation for the introduction of a sealing compound. A pressure relief structure, such as a gas bubble, may be provided within the fluid to relieve the pressures incident to the thermal expansion and contraction of the electrode assembly. Because of the water repellancy of the fluid, the electrolyte solution which surrounds the electrode assembly is prevented from migrating into the interior thereof and thereby initiating output current errors.

Abstract: An improved apparatus for facilitating the practice of a method for determining the conversion efficiency of the NOx converter of an oxides of nitrogen analyzer. An improved ozone control assembly facilitates the control of the ozone content of the gas mixture that is applied to the input of the analyzer. An improved gas flow regulating arrangement allows the composition of the gas mixture to be changed without affecting the flow rate thereof. Together, these structures improve the stability and ease of use of the conversion efficiency detector.

Abstract: A carbon monoxide detection apparatus and process are disclosed in which the amount of carbon monoxide is measured by oxidizing it and measuring the heat of oxidation. To accomplish this platinum oxide is used as the catalyst and an operating temperature is maintained at which oxidation of carbon monoxide occurs in the presence of platinum oxide. Various types of heat-change-responsive techniques are disclosed, including measurement of the voltage drop across forward-biased solid-state diodes, and measurement of the voltage generated by thermo-couples.

Abstract: A gas analyzer is disclosed which provides a dual channel capability for the simultaneous determination of the presence and concentration of two gases in a stream of sample gas and which has a single infrared source, a single sample cell, two infrared bandpass filters, and two infrared detectors.A separator between the filters and detectors prevents interchange of radiation between the filters. The separator is positioned by fitting it in a slot.

Abstract: An improved hydrazine analyzer is disclosed wherein sample and electrolyte solutions are supplied from constant flow rate sources into a mixing chamber where they are premixed. The premixed combination of electrolyte and sample is then passed through a sensing chamber having a sensing thimble disposed therein. The thimble is of a porous material having a platinum wire electrode wound about the outside thereof and having a silver wire inserted into silver chloride salt on the inside thereof to form a reference half cell. As the electrolyte-sample mixture passes through the sensing chamber, a portion of the fluid passes from the outside of the thimble to the inside of the thimble wetting the silver chloride salt to establish electrical contact and provide the internal filling solution of the reference half cell.

Abstract: An ink priming system for a multi-pen recorder of the gravity-fed capillary tube type comprises a gas manifold common to all of the ink bottles individually provided for each channel of the recorder. Individual control valves may be selectively actuated by the operator to prime each pen. When the control valve is closed, the gas pressure is bled off so that the inking system thereafter acts as a normal gravity-fed capillary tube system. A non-clogging inking system is provided by utilizing a short length of flexible thin walled tubing to supply ink to the movable recording pen. The length of this tubing is sufficiently short that evaporation of the ink solvent through the walls of the tube is accompanied by diffusion of the dye back to the ink bottle so that the concentration of dye in the ink at the end of the tube adjacent the recording pen does not exceed saturation value during prolonged periods of non-use of the recorder.

Abstract: In a sulfur dioxide analyzer which measures the content of sulfur dioxide by fluorescence of sulfur dioxide molecules when illuminated by an ultraviolet light source, there is disclosed a converter containing vanadium pentoxide for removal of polynuclear aromatic hydrocarbons which produce interference when sulfur dioxide is measured by fluorescent methodology.

Abstract: In a sulfur dioxide fluorescence analyzer, a method and apparatus for eliminating the fluorescence effects of nitric oxide is disclosed wherein a sample gas is mixed with a diluent which substantially quenches nitric oxide fluorescence.

Abstract: A keyboard type switch is disclosed wherein a domed snap disc performs triatic functions of acting as a tactile feedback source for switch operation, of supplying a conductive path for electrical energy when depressed, and of providing a contact surface for manual operation. The disclosed switch is covered by a multilayered nonconductive membrane and spacer to provide maximum safety from electrical shock to the operator.

Abstract: A multi-channel instrumentation system is provided wherein signals from selected electrode pairs are sequentially connected to the isolated input of a common signal amplifying path. The electrode pair selecting means is included in a portable head box which may be placed adjacent to the patient to be tested. Included in the head box are facilities for testing the impedance of any selected one of the patient electrodes and providing a visual indication of the magnitude of such impedance. The head box also includes facilities for selecting a group of patient electrodes which are connected together and used as an average or reference potential for one input of the common signal path. Facilities are also provided for calibrating the common signal path by applying a d.c. calibration signal to the input thereof by means isolated from system ground.

Abstract: A method and apparatus for removing moisture from a sample stream of gas while preventing dilution of the concentration of components of successive increments of the sample stream of gas.

Abstract: An improved electroencephalograph system is disclosed having a system for automatically verifying the input and output parameters of the various channels, the preset number selected, and a patient identification number. A coded output is used employing the standard EEG pen recorder outputs. Numerical sequences such as the preset number and a patient identification number are displayed on a single event marker channel as modified Roman numeral sequence of digits directly readable by the operator.

Abstract: An ink priming system for a multi-pen recorder of the gravity-fed capillary tube type comprises a gas manifold common to all of the ink bottles individually provided for each channel of the recorder. Individual control valves may be selectively actuated by the operator to prime each pen. When the control valve is closed, the gas pressure is bled off so that the inking system thereafter acts as a normal gravity-fed capillary tube system. A non-clogging inking system is provided by utilizing a short length of flexible thin walled tubing to supply ink to the movable recording pen. The length of this tubing is sufficiently short that evaporation of the ink solvent through the walls of the tube is accompanied by diffusion of the dye back to the ink bottle so that the concentration of dye in the ink at the end of the tube adjacent the recording pen does not exceed saturation value during prolonged periods of non-use of the recorder.

Abstract: A system for continuous monitoring for open circuits in multiple lead EEG systems during patient testing. Means are provided for repetitively applying a low current signal, having a distinctive waveform and frequency, to each electrode of the system. In the event an electrode is detached from the patient's scalp or otherwise open, the distinctive signal is apparent in the recorded output. Otherwise the distinctive signal is of such low magnitude that it is below the signal-to-noise ratio of the EEG amplifier. In systems including multiple leads, the test signal is successively applied to each electrode in the system in a time-controlled sequence. In one preferred embodiment a distinctive signal is used comprising a four pulse burst of 25 Hz frequency.