Abstract: The bead source for the thermionic detector of a gas chromatograph is heated by the secondary winding of a transformer having a center-tapped primary and operating in the push-pull configuration. The voltage drop across the bead is compared with a preselected reference voltage and an error signal is generated. The error signal is used to control the output of a pulse width modulation control which supplies the transformer primary winding.

Abstract: An instrument for performing highly accurate PCR employing a sample block in microtiter tray format. The sample block has local balance and local symmetry. A three zone film heater controlled by a computer and ramp cooling solenoid valves also controlled by the computer for gating coolant flow through the block controls the block temperature. Constant bias cooling is used for small changes. Sample temperature is calculated instead of measured. A platen deforms plastic caps to apply a minimum acceptable threshold force for seating the tubes and thermally isolates them. A cover isolates the block. The control software includes diagnostics. An install program tests and characterizes the instrument. A new user interface is used. Disposable, multipiece plastic microtiter trays to give individual freedom to sample tubes are taught.

Abstract: The present invention is directed to a nebulizer for use in an atomic absorption system which includes a capillary assembly having a capillary holder having an internal axial passage therethrough, a sapphire capillary tip mounted on one end of the capillary holder and the other end of the holder being connected to a sample liquid source through a capillary gland nut assembly. A venturi member is provided which has an inlet portion, a throat portion and an exiting bell shaped portion. A body assembly has one end connected to the venturi member. The capillary assembly is mounted on the body assembly for axial movement so that the capillary holder partially enters the venturi inlet portion and the capillary tip enters the venturi throat. Compressed oxidant is supplied to the venturi member in the vicinity of the capillary tip so as to suck sample liquid from the capillary tip to form a mixture of fine liquid mist and gas which is discharged through the exiting bell shaped portion.

Abstract: This invention is directed to a plastic holder assembly for loosely holding a plurality of microtiter sample tubes, which includes a tray having a plurality of holes for receiving the tubes and having opposite vertical end walls, each of which have two spaced vertically extending slots and a horizontally extending recess between the slots; a retainer releasably nestable in the tray having a corresponding plurality of holes and having opposite vertical end walls corresponding to the end walls of the tray; a U-shaped handle extending horizontally outwardly from each of the opposite retainer end walls, each handle having two legs which slide into the tray slots respectively when the retainer is nested in the tray; a tab projecting horizontally outwardly from each of the retainer end walls between each of the two legs which snap into the tray end wall recesses respectively when the retainer is nested in the tray, the retainer having an elongated slot parallel and directly adjacent each of the end walls, whereby i

Abstract: A capillary flowcell of this invention comprises a holding means including an optical axis, the optical axis being defined by, in sequential order, (a) a first (entrance) aperture, (b) a first lens, (c) a capillary tube having its long axis centered across the optical axis, and (d) a second lens. The first lens focuses electromagnetic radiation from the entrance aperture passes through the inner diameter of the capillary tube, thus maximizing the signal generated by the analyte within the capillary tube. The second lens focuses electromagnetic radiation which has passed through the capillary tube. Methods and apparatus pertaining to the flowcell are given.

Abstract: A method of filling a capillary with a substantially void-free gel by forming the gel outside of the capillary and then extruding the gel into the capillary. The initial gel can be formed as a rod of gel much larger in diameter than the capillary into which it is to be extruded. This rod of gel is rinsed to remove polymerization contaminants and then dried to form a dried gel preform. The gel can be resolvated with a compatible solvent and then extruded into one or more capillaries.

Abstract: In a spectrophotometer, each of a plurality of source optical fibers is selectively receptive of source radiation and carries the radiation to a corresponding selected liquid sample cell. A corresponding return optical fiber returns transmitted radiation from the sample to a polychromator. For selecting a sample, a switching member holds exposed ends of the optical fibers on a circle coaxial with an axle for rotating to selected positions. Respective optical trains in the instrument direct radiation into and out of the selected pair of fibers. The diameter of a source aperture, the spacing of the aperture from the radiation source, and the source area define a source etendue. The optical fibers have a fiber etendue substantially the same as the source etendue.

Abstract: A method and apparatus are provided for correction of spectra for stray radiation in a spectrometric instrument, involving a sequence of steps as follows. Spectral patterns are obtained with the instrument initially for monochromatic radiation at a plurality of selected calibration wavelengths. By computer program, the peak profile at the calibration wavelength in each pattern is replaced with a substitute based on the remaining pattern. The resulting data are interpolated to effect values denoted "stray proportions" for the ordered wavelengths of the instrument. Spectral data at each ordered wavelength are obtained with the instrument for a sample, and multiplied in the computer program by stray proportions for corresponding wavelengths to effect further sets of values denoted "stray portions" that are identified to the ordered wavelengths. Each set is identified to one of the wavelength increments of the instrument across the spectral range.

Abstract: A Capillary Electrophoresis apparatus and method are disclosed which utilize a meltable plug in an end of the capillary tube to selectively pass small ionic contaminants electrophoretically and retain macromolecular analytes against one end of the plug until the plug is melted. When this plug is melted, the analytes and the contaminants pass through unimpeded. This permits separation of the analytes from the contaminants during electrophoretic separation and enhances instrument resolution.

Abstract: Spectral bands are grouped for data acquisition in a spectrophotometer with a charge-coupled detector having a plurality of pixels. Preliminary data is generated on time-integrated radiation to the pixels for a sample. Maximum permitted exposure times for the pixels are calculated from the data and a predetermined maximum exposure. The maximum times are grouped so that for each group the ratio of the highest to the lowest maximum times is less than 100. A group run time is established for each group nominally less than the lowest maximum time in the group. Subgroups are created and ordered so that accumulated readout times for the pixels are less than wait times established to prevent readout contamination from subsequent charge buildup. The spectrophotometer is further operated on the sample for the run time of each group and subgroup to generate spectral data.

Abstract: A complete in situ PCR system for amplification of nucleic acids contained in a prepared cell or tissue sample. The containment system for the PCR sample comprises a glass microscope slide, a specimen sample containing the target nucleic acid sequence mounted on the slide, a flexible plastic cover over the sample, and a retaining assembly fastened to the slide and to the cover to retain and seal a reaction mixture against the sample during thermal cycling. The retaining assembly includes a rigid ring on a rim portion of the cover, a cross beam having spaced parallel rails joined by opposite flat ends, and a pair of clips which are pressed over the ends and opposite sides of the slide to fasten the cross beam and cover to the slide.

Abstract: A plunger homing mechanism for use in automated chromatography. A plunger cap holder holds the plunger cap of a syringe within a housing. The housing is biased with an isolation spring within a casing. The casing is raised and lowered to move the syringe plunger held within the housing. When the casing is lowered and the plunger hits bottom, the relative movement between the housing and the casing is detected by a sensor. The casing movement is then caused to stop. This permits the detection of a home or reference position for the accurate and precise withdrawal of a sample to be analyzed. Additionally, damage to the syringe from over driving the plunger rod is prevented.

Abstract: A tenacious wear resistant coating is applied with a high velocity oxygen-fuel thermal spray gun using a composite powder of aluminum and an iron base metal. The metal may be iron-chromium, iron-molybdenum, cast iron or a combination. A particular combination is a blend of a first powder and a second powder, the first powder consisting of a composite of aluminum subparticles and iron-molybdenum alloy subparticles, and the second powder consisting of a composite of aluminum subparticles and cast iron subparticles. An internal combustion engine block has such a coating applied to the cylinder walls.

Abstract: In a fluid valving system, binary fluid control lines are connected in parallel between a common fluid inlet and a common fluid outlet. Each line has a binary valve and a metering orifice for passing a predetermined rate of fluid flow. The rates are in a geometric progression in factors of two. An analog fluid control line is connected in parallel with the binary lines, and has a continuously adjustable flow rate regulator for passing any selected rate of fluid flow up to a maximum at least equal to the largest increment of rate change in the binary lines. The regulator is formed of a miniature solid state device. A controller sets each binary valve open or closed, and sets the regulator for a selected flow rate, such that cooperative settings provide for a smoothly variable rate of total fluid flow.

Abstract: In order to provide a linear calibration graph when analysing samples by atomic absorption spectroscopy, a maximum absorbance value is determined conventionally for a given analyte. The individual absorbance values of a sample containing an unknown amount of the analyte are processed as a function of the maximum absorbance value in accordance with the function ##EQU1## The thus obtained corrected individual absorbance values are integrated with respect to time to yield a corrected time-integrated absorbance value which is proportional to the amount of analyte present in the sample. This amount is determined using a calibration factor obtained from the analogously corrected time-integrated absorbance value of a calibration sample containing a known amount of the analyte.

Abstract: An instrument for surface analysis includes a gun for selectively focusing an electron beam on an anode spot, or rastering the beam across an array of such spots, to generate x-rays. A concave monochromator focuses an energy peak of the x-rays to a specimen surface, in a spot on a selected pixel area or across an array of pixel areas on the surface to emit photoelectrons. An analyzer with a detector provides information on the photoelectrons and thereby chemical species in the surface. A second detector of low energy photoelectrons is cooperative with the rastering to produce a scanning photoelectron image of the surface, for viewing of a specimen to be positioned, or for imaging an insulator surface. The monochromator is formed of platelets produced by cutting an array of platelets from a single crystal member, and bonding the platelets to a concave face of a base plate juxtaposed in crystalline alignment in a positioned array identical to that of the initial array.

Abstract: A method for determining concentration of an analyte in a sample includes generating a spectrum of a selected analyte and interferents, generating a spectrum of an unknown sample, computing first and second derivatives of the sample spectrum, deriving a matrix model that includes the analyte spectrum and the derivatives, and applying the matrix model to the sample spectrum so as to yield a parameter representing concentration of the selected analyte in the unknown sample. Multiple linear least squares regression is utilized to fit the model and calculate the parameter.

Abstract: An apparatus for analyzing the dielectric properties of a sample. A thin planar sample having a hole therein is positioned over two bottom electrodes having the hole over one of the bottom electrodes. An oscillator provides a first signal to one of the bottom electrodes and a second signal 180.degree. out of phase with the first signal to the second bottom electrode. A differential signal is obtained on the top electrode representative of the dielectric properties of the sample with the elimination of edge effects. A phase sensitive demodulator synchronized with the oscillator extracts the two components of the conductance and susceptance of the sample. A position sensor measures the thickness of the sample and is used to calculate the dielectric constant of the sample. Thereby, an accurate measurement of the dielectric properties of the sample is obtained without a complicated structure in order to eliminate edge effects.

Abstract: A spectrometric instrument which exhibits an intrinsic profile for a sharp spectral line produces profile data for narrow spectral lines. The spectral lines are effected with a high finesse etalon of gold coated polymer. A transformation filter is computed for transforming the profile data to a gaussian profile. A wavelength calibration is combined with the filter to effect a correction matrix which is applied to sample data to generate calibrated standardized data. Iteratively a correction matrix is applied to calibration data to generate standardized calibration data which is utilized for the wavelength calibration. Calibration is effected with an optical standard, an interference etalon and a fringe formula. Etalon effective thickness is first estimated and then precisely determined so that fringe peaks calibrate wavelength.

Abstract: A method of producing spectral data corrected for background includes generating spectral data, ascertaining background and subtracting background points to produce the corrected data. To ascertain background the spectral data are masked initially at the spectral peak of interest, and a least squares curve is fitted to the masked data. A runs test is performed to detect whether the number of runs exceeds a selected significance level. If so, the data are further masked and a curve is refitted. These steps are iterated until no further significant number of runs is detected. Similar testing for outliers is then effected with similar masking, a final curve represents the background level.