Abstract: In a process for mixing two initial solutions to produce a working solution with an accurately defined mixing ratio, the two initial solutions are coarsely mixed in a first step, having a mixing ratio lying within a given range, and the value of an internal parameter of the working solution is determined in a second step. The values of this internal parameter are known and differ significantly for the two initial solutions. Then the accurate mixing ratio of the working solution is determined from the measured value of the internal parameter in a third step.

Abstract: A silicon wafer is placed in an atmosphere of hydro-fluoric acid vapor, dissolving an oxide film formed on a surface of the wafer and forming solution drops containing impurities. A Teflon plate is put on the surface of the silicon wafer, such that its hydrophilic surface is set in contact with the HF solution drops. The drops are transferred to the hydrophilic surface of the Teflon plate. Fluorescent X rays are applied to the hydrophilic surface of the Teflon plate and totally reflected the hydrophilic surface. The energy peaks of the impurities, including aluminum whose energy peak is similar to that of silicon, are detected from the fluorescent X rays totally reflected. Also, the distribution of the impurities in the surface of the wafer are determined from the fluorescent X rays.

Abstract: A method in which a temperature gradient is generated across a "gradient" block, and an apparatus comprising a block across which a temperature gradient can be generated. By setting up such a gradient, multiple reaction mixtures held in wells on the gradient block can be simultaneously run at temperatures which differ only slightly, thereby permitting an optimum temperature for the reaction to be quickly identified. In a preferred embodiment the gradient block is integrated into a thermal cycler used for nucleic acid amplification reactions.

Abstract: A combustible gas sensor having a noble metal sensor element with a surface that is heated above a critical temperature at which the surface is able to dissociate oxygen in a gas stream and adsorb the oxygen onto its surface. The adsorbed oxygen present on the noble metal surface enhances the reactivity of the sensor element and permits it to react with combustible gases that otherwise would have little or no affinity for the sensor element. The balance of adsorbed oxygen and combustible gas species on the sensor surface cause a change in an electrical property that is used to determine the presence or identity of a combustible gas, or to derive a concentration measurement.

Abstract: The present invention relates to a sensing instrument and method for measuring the concentration of an analyte. The sensing instrument includes: a sensing element including at least a first emissive indicator characterized by a bimolecular quenching rate constant k.sub.q, one or more fluorescence lifetimes .tau..sub.o above a lowest lifetime .tau..sub.oL, and capable of emitting analyte concentration dependent signals when exposed to an excitation signal in the presence of quencher; an excitation system which provides an amplitude modulated excitation signal at one or more radial modulation frequencies .omega.; a detector; and a processor. The processor univariantly processes the detected signals and provides output signals representative of analyte concentration. The sensing element and/or excitation system are configured to enable the instrument to operate sufficiently within the condition [(k.sub.q [Q]).sup.2 +.omega..sup.2 ].tau..sub.o.sup.2 >>1+2k.sub.q .tau..sub.

Abstract: A diffused light reflectance readhead is disclosed. The readhead employs an improved light emitting diode (LED) providing a more strongly collimated beam of light around a beam axis onto a reagent test pad. The reagent test pad is supported on a strip guide at an angle .alpha. of 5 degrees with respect to the perpendicular of the beam axis. It has been discovered that when .alpha. is between 3 and 8 degrees that specular reflection is dramatically reduced in relation to the small reduction in reflected light received by a sensor. The diffuse reflected light travels to the sensor by passing through a staircase optical baffle at an angle of 45 degrees to the perpendicular of the beam axis. The sensor converts the optical signal into an electrical one for processing and analysis. One embodiment of the present invention can detect the presence of glucose in a blood sample.

Abstract: A first reactant is immobilized i.e. in a porous matrix (50), adjacent a sample electrode (46) within a reaction chamber. Energizing of the electrode (46) electrophoretically attracts a mobile second reactant and/or electrolytically induces appropriate reaction conditions to enhance reaction of the first and second reactants. Polarity reversals between the sample electrode (46) and remote electrodes (38), (42), (44) cause unreacted second reactant and/or by-products to migrate away from the immobilized first reactant. The techniques are useful for sequential chemical reactions such as sequencing or construction of proteins, polysaccharides and nucleic acids where cyclical additions and removals of reactants are required. The techniques are amenable to automated micro and nano scale construction and operation and allow direct electrophoretic (38) interfacing with chromatographic, HPCE and mass spectrophotometric equipment.

Abstract: One or more properties of a refrigerant sample, such as composition, purity or both composition and purity, are analyzed for purposes of refrigerant recovery and reuse by providing a refrigerant cell having a chamber for containing a refrigerant sample and a passage for connecting the chamber to a source of refrigerant in vapor phase. The sample chamber and passage are evacuated, and the chamber and at least a portion of the passage contiguous with the chamber are cooled until the temperature thereof reaches a predetermined temperature at or below ambient temperature. After the chamber and passage have been evacuated and cooled, the passage is connected to a source of refrigerant in vapor phase such that a refrigerant vapor sample is drawn into the chamber and condensed to liquid phase. After the cell chamber has been filled with a liquid refrigerant sample, one or more desired properties of the liquid refrigerant sample are measured or detected.

Abstract: Automatic apparatus for immunological assay, in which reaction vessels containing samples to be analyzed and reagents are carried by a rotary module which is rotated stepwise, and which is associated with a washing head including needles for sucking up and for injecting liquid for washing magnetic particles in the reaction vessels, and additional needles for sucking up and for injecting a cleaning or washing liquid for the reaction vessels.

Abstract: The presence of trace materials in a sample is detected using both macroscopic and microscopic properties. A detector includes a light source and an optical resonator. The light source may be located either inside the resonance cavity of the resonator or outside the cavity, in which case it may be a semi-conductor such as a semi-conductor laser or a superluminescent diode. The detector also includes at least one reflective member that has a total internal reflection (TIR) surface and may be a passive device or an active gain element. Light from the light source is preferably focussed onto a single point of reflection on the TIR surface. The test sample is positioned within the evanescent field region of the TIR surface. Optical changes arising within the evanescent field region, such as excitation of fluorescence in the sample, changes in its refractive index, and changes in the resonant frequency of the optical resonator, are then detected.

Abstract: An analyzer has a horizontally disposed baseplate on which primary containers and secondary containers are disposed, a pipetting needle, a transport device, and a control device. The pipetting needle is formed of an electrically conductive material and is connected to a metering device by a tubing, and is for transferring a predetermined volume of liquid each time from a primary container to a secondary container. The transport device is for the controlled transport of the pipetting needle in three directions at right angles to one another, two of the transport directions extending horizontally and the third transport direction extending vertically. The control device is for controlling the metering device and the transport device.

Abstract: The present invention is an optical detection and identification system and provides an optic sensor, an optic sensing apparatus and methodology for detecting and evaluating one or more analytes or ligands of interest, either alone or in admixture. The optic sensor of the system is comprised of a supporting member and an array formed of heterogeneous, semi-selective thin films which function as sensing receptor units and are able to detect a variety of different analytes and ligands using spectral recognition patterns.

Abstract: An automatic calibration technique for a gas analyzer includes applying electrical energy to a source that is different from the level used to detect gas concentration in order to produce a different level of radiation from that used to detect gas concentration. The different level is applied with a non-absorbing gas in the gas sample chamber. The detector output at the reduced level is resolved to a calibration factor. The instrument can be linearized by repeating the calibration procedure at multiple different levels of reduced source radiation. In one embodiment, source assembly (26) is provided that includes a plurality of infrared emitters (36) to which is applied modulated electrical energy in a timed sequence in order to produce output levels for three component gas concentrations. A filter (56) between each one of the sources (36) and a detector (50) pass radiation at an absorption line of one of the component gases.

Abstract: A storage and incubation apparatus for temperature sensitive medical test samples includes a clear rack mounted on a base and having a plurality of shelves for supporting one or more test sample slides. The rack includes opposing panels joined by a transverse member and/or a side member, and having an open side defined thereon. The rack is clear to permit viewing of the slides during incubation. Furthermore, a heating element including a thin metal strip is mounted on the interior of the rack directly opposite the test samples to maintain the temperature of the test samples within a narrow predefined range.

Abstract: An accurate, rapid and simple method of determining blood coagulation factor XIII activity and a kit of reagents therefor are provided. A sample and a fibrin precipitation inhibitor are mixed, or a sample, fibrinogen and a fibrin precipitation inhibitor are mixed; a thrombin solution is added; the fibrin coagulation time is measured in the presence of calcium ion; and the coagulation time is compared with the normal coagulation time. The kit for the determination comprises thrombin, calcium ion and a fibrin precipitation inhibitor, and may be combined with fibrinogen.

Abstract: A method of assessin glycated blood protein in a sample which comprises separating glycated and non-glycated protein using a liquid phase precipitation reagent, contacting the sample before or during the separation with a signal forming agent capable of binding preferentially to the glycated protein, and assessing the signal forming agents.

Abstract: A spectroanalytical system includes housing structure with vent structure open to the atmosphere; radiation dispersing apparatus in the housing structure for dispersing radiation into a spectrum for application to sensor apparatus; sample excitation apparatus for exciting sample material to be analyzed to spectroemissive levels for generating a beam of radiation for dispersion by the dispersing structure; a source of gas; structure for flowing gas from the source into the housing structure for exhaust from the housing structure through the vent structure at a flow rate that is less than one percent of the volume of the housing structure per hour; first control structure for maintaining the pressure of the gas in the housing structure at a constant (within about one millibar) pressure independent of atmospheric pressure; and second control structure for maintaining the temperature of the gas within the housing structure constant within about 0.1.degree. F. during system operation.

Abstract: The invention is directed to a detecting device for detecting gaseous substances and aerosols with the aid of an enzymatic reaction. This reaction takes place between a reactant and an enzyme which, on the one hand, is exposed to the substance to be detected and, on the other hand, is held by a carrier which in the form of a porous holder is in contact with a solution activating and maintaining the enzymatic reaction. The properties of the solution are changed by the enzymatic reaction and are evaluated. The detection device is so improved that a capability for evaluation is made possible which is quantitative and which is specific for a particular substance to be detected. The substance to be detected as a reactant can be stoichiometrically transferrable into a reaction product for quantitatively determining the substance to be detected by means of an enzymatic reaction.

Abstract: A testing device having a lower cup for receipt of a fluid specimen and a cover lid containing a strip chamber having one or more reagent strips disposed therein and having a test chamber for each of the reagent strips, such test chamber receiving the end portion of the reagent strip, with each of the reagent strips having a color change testing area along its length. The cover lid is attachable to the cup in fluid-tight relationship with the device to be inverted for the fluid specimen to reach the reagent strips in the test chambers and react therewith, and for the device to be set upright for the reading of the color change testing areas through windows in the cover lid above the color change test areas.

Abstract: The present invention relates to a multiple-duct tube for centrifugal separators for blood in particular, suitable for connecting a rotating connector to a stationary connector. The multiple-duct tube comprises, in a monolithic structure, a plurality of ducts which have parallel axes. The outer surface of the tube is defined by blended portions of walls of the peripheral ducts, so as to assume a lobate shape in a transverse cross-section.