Abstract: The present invention is directed to a shell type centrifuge rotor formed as a frustoconical shell having a circular rim adjacent at least one end thereof. The lower end of the shell is open, whereas the upper end has a conical recess and a central opening. The recess has an inverted frustoconical sidewall, with a plurality of apertures equally spaced therein and disposed an equal distance from the central opening.A tube holder is mounted in each of the apertures for receiving a centrifuge test tube. The tube holder has a flange configured so as to fit the surface contour of the conical recess so that the flange fully contacts the wall of the conical recess when the tube holder is mounted in the aperture. A hub is mounted in the central opening of the conical recess and couples the frustoconical shell to the centrifuge drive shaft. Means are secured to the hub for partially enclosing the lower end of the frustoconical shell to reduce the windage of the rotor to a predetermined level.

Abstract: An improved method for producing an electrode assembly for use in electrochemical gas sensors. A plurality of conductors are attached to one surface of a generally circular electrode blank. These conductors are passed through respective conductor routing holes in an electrically nonconductive mounting member. After the electrode blank is attached to the mounting member, predetermined sections of the electrode blank are cut away to divide the blank into a plurality of electrically isolated regions that are connected to respective conductors. The cut-away sections may then be filled with an electrically nonconductive filling material to provide the electrode assembly with a smooth, flush surface.

Abstract: Balancing bosses integrally forged in a centrifuge rotor. The plurality of balancing bosses in the rotor establish noncritical areas in the rotor for machining to accomplish the precise balancing necessary for high speed ultracentrifugation. The balancing bosses are located away from the high stress periphery of the rotor so that machining a portion of the bosses for balancing purposes will not degrade the integral strength of the rotor.

Abstract: There is disclosed a method and apparatus for implementing a narrow band rejection filter utilizing a liquid crystal cell. A liquid crystal cell is positioned in the path of a light beam between a pair of crossed or parallel polarizers with the optical axis of the cell at a 45.degree. angle to the optical axes of the polarizers. A voltage is applied to the cell to tune the cell to reject a given wavelength and to pass other wavelengths. In order to reject the given wavelength and pass all other wavelengths, the order of the cell is stepped to maintain rejection of a fixed wavelength and the detected signal from the light passing through the cell is averaged.

Abstract: A high pressure valve for control of the injection of a sample into an analyzer system such as an amino acid analyzer with liquid column chromatography. The valve is designed in such a manner that no rinse solution that is used to cleanse the system after the injection of a particular sample will enter the liquid column. The valve operates in two positions and requires a minimum of movement between the two positions. In one position the valve allows for the injection of the sample into the liquid column. In the second position the valve allows for the entry of only a buffer solution into the liquid column and blocks the entry of any rinse solution that may flow through the system for cleansing after the injection of the sample. No residual rinse solution is allowed to remain within the valve prior to injection of either a sample or a buffer material into the liquid column.

Abstract: Plunger operated pipet operable to execute different lengths of plunger movement during successive fluid pickup and fluid discharge operations or strokes. A stop member is movable between first and second locations in the pipet body to halt plunger movement at two different positions. A drive spring for driving the stop member from one location to the other is energized by a manually operable arming element and is retained in one location against action of the drive spring during a first plunger stroke. A release mechanism responsive to plunger movement during the first stroke disables the retaining means allowing the drive spring to move the stop member to the second location at which position the plunger is halted during the succeeding discharge stroke. The arming element is actuated by and in response to positioning of a replaceable tip on the pipet body.

Abstract: A display system and method utilizing a common character generator among a plurality of display devices. Each display device generates address signals which are multiplexed and applied to the character generator. The output from the character generator is used to control the visual representation produced by each display device. A graphics memory of picture elements can be addressed for a composite display of graphics and alphanumeric characters by the various display devices.

Abstract: The present invention is directed to a circuit for generating a voltage for compensating the output of a thermocouple. The circuit provides a compensating voltage to enable the thermocouple to be operated with its reference junction at ambient temperature. The compensation voltage varies linearly with changes in the ambient temperature and passes through zero volts at 0-20 C. The compensation voltage is generated by combining a temperature variable voltage developed across one or more semiconductor junctions with a constant voltage of opposite polarity.

Abstract: A liner for use in a centrifuge rotor bucket for converting a single cavity bucket into a multicavity bucket to provide separate support for at least two flexible fluid sample containers. The liner has a separation ridge which defines at least two areas in the liner, but allows maximum space for receipt of the flexible containers. Handle means are attached to the liner to provide ease in the removal and insertion of the liner into the rotor bucket.

Abstract: A solution of the type comprising cobalt ammonium sulfate and sulfuric acid. The solution is characterized in that it comprises from about 0.020 to about 0.040 N H.sub.2 SO.sub.4.Also, a method for checking the linearity of response of a spectrometer or spectrophotometer. The method is of the type comprising measuring absorbance (A) or percent transmittance (%T) of a solution versus a blank at a known wavelength. The method is characterized in that the above solution is employed therein.In addition, a method for checking photometric accuracy of a spectrometer or spectrophotometer. The method is of the type comprising measuring A or %T of a solution at a specific wavelength. The method is characterized in that the above solution is employed therein.

Abstract: A video display memory expansion system for expanding the graphics memory within the video display. The memory expansion system is suited for increasing the resolution of a graphics display from a low-resolution to a high-resolution display. A video display device is adapted to receive a relatively simple graphics memory expansion accessory to thereby easily and inexpensively provide the increased graphics memory capability.

Abstract: Gain hysteresis exhibited by the photomultiplier detector of a single beam spectrophotometer is reduced by illuminating the detector and applying dynode voltage thereto during the normal "off" or "idle" interval of the spectrophotometer.

Abstract: An elongate straight column for use as a reactor in an analytical instrument. The column contains inert packed material which provides for the necessary flow path length for a fluid stream entering the reactor. Fittings are incorporated onto the ends of the column in such a manner that their width is no larger than the width of the column. The column configuration for a reactor allows more versatility in the type of temperature regulator mechanisms used to heat and cool the reactor.

Abstract: Gain hysteresis exhibited by the photomultiplier detector of a single beam spectrophotometer is reduced by illuminating the detector and applying dynode voltage thereto during the normal "off" or "idle" interval of the spectrophotometer.

Abstract: A photomultiplier detector protection system and method utilizing a negative feedback loop to maintain the photomultiplier detector output below a predetermined output. The feedback loop comprises a comparator responsive to the photomultiplier detector output and also responsive to a predetermined limit signal. The comparator output is applied to a summing amplifier which also receives a voltage adjust signal. The output of the summing amplifier controls the output of a power supply which is in turn applied to the photomultiplier detector.

Abstract: Plunger operated pipet operable to execute different lengths of plunger movement during successive fluid pickup and fluid discharge operations or strokes. A stop member is movable between first and second locations in the pipet body to halt plunger movement at two different positions. A drive spring for driving the stop member from one location to the other is energized by a manually operable arming element and is retained in one location against action of the drive spring during a first plunger stroke. A release mechanism responsive to plunger movement during the first stroke disables the retaining means allowing the drive spring to move the stop member to the second location at which position the plunger is halted during the succeeding discharge stroke. The arming element is actuated by and in response to positioning of a replaceable tip on the pipet body.

Abstract: For use in a system for analyzing sample constituents by metastable transfer emission spectroscopy, an improved apparatus for mixing a sample gas with a metastable gas. The apparatus provides an unobstructed path for the flow of sample gas so as to minimize deposition of the sample on walls of the apparatus. The apparatus may comprise an annular manifold coaxially mounted around a conduit through which flows the sample, or it may comprise a collar detachably connected in line with such a conduit.

Abstract: A one piece integrally formed sectional shaped liner for use in combination with similarly shaped sectional liners in a generally cylindrical chamber of a centrifuge rotor. The utilization of a plurality of similarly shaped plastic liners within a single rotor chamber allows for the placement of different fluid samples in a single rotor during one centrifuge run. The liners are designed in such a manner that they do not require a separate capping means and are preferably made through a blow molding process. The liners are designed to provide adjacent support to each other during the centrifugation run.

Abstract: A molded one-piece housing for use in fabricating conductivity cells. An electrically nonconducting housing includes an internal partition which divides the interior of the housing into a first region for receiving a test liquid and a second region for receiving a plurality of electrical conductors. Openings through the partition provide passages through which measuring electrodes may project into the first region to establish cell constants of the desired magnitude. These openings are so shaped that they establish a liquid-tight seal between the housing and the electrodes during insertion. By means of this seal the electrodes are held firmly in place during the assembly of the cell. This seal also permits a potting compound to be introduced into the second region without leaking onto and thereby affecting the electrical characteristics of the electrodes.

Abstract: A method for checking noise of a spectrometer or spectrophotometer. The method is of the type comprising measuring absorbance (A) or percent transmittance (%T) of a solution over a period of time. The method is characterized in that the solution comprises from about 0.040 to about 0.090 M nitrite, the nitrite being present as a nitrite ionized constituent.