Abstract: A portable, manually operable device for preparing a monolayer film of a biological fluid sample or the like on a slide for microscopic examination. Said device includes a base for retaining the slide thereon and a spreader manually movable linearly relative to the base and slide in a pass which spreads a sample of the fluid on the slide into such a monolayer. Preferably, the spreader is constructed to be disposable.

Abstract: A microscopy system for automatically locating and re-locating objects-of-interest in an image which has one or more objects against a background. Each of the objects-of-interest is characterized by a predetermined set of features. In a preferred form, the invention is specifically directed to an automated microscopy system which is adapted for automatically analyzing biological (e.g., blood or cervical) cells on microscope slides. In other forms of the invention, differing types of objects may be identified as being objects-of-interest during a first automated pass and then re-located during a second pass for further analysis.

Abstract: Flat beam optical sensing performed transverse of a flow aperture, of the particles passing through the aperture, directly indicates the presence of individual particles in the aperture. The indication can be used to eliminate or otherwise modulate the coincidence errors resulting in particle measurements taken through the length of the aperture.

Abstract: A liquid diluting valve assembly for delivering a pair of different sample volumes in the microliter range along with a predetermined volume of diluent to different locations. The valve assembly includes a pair of outer discs and an inner disc sandwiched therebetween, the facing surface portions being sealingly frictionally engaged. The discs have central axial passages aligned to accommodate a spindle the inner disc being independently movable relative to the other discs. The discs carry passageways with at least one segmenting passageway provided in the inner disc. One of the outer discs is stationary and carries an external hollow loop having a precise volume in the microliter range. The other outer disc carries a single outwardly extending aspirator probe for introduction of a liquid sample from an exterior sample source, the probe being coupled in series with the external hollow loop.

Abstract: An air vacuum chuck for a microscope includes a body member having a planar slide-supporting surface. Stop members are adapted to align a slide in a predetermined orientation. Air ports and vacuum ports in the slide-supporting surface selectively couple a relatively high pressure air reservoir and a vacuum reservoir, respectively, to the region between the slide-supporting surface and the object-bearing surface of the slide. The air ports are adapted to provide airflow directed towards at least one of the stop members. In an alignment mode, airflow from the air ports and vacuum from the vacuum ports establish a vacuum-retained air-bearing with a substantially frictionless coupling between a slide and the slide supporting surface. The vacuum from the vacuum ports controls the separation between the slide and the slide-supporting surface. The directed airflow imparts a net force on the slide, positioning the slide against the stop members.

Abstract: Automatic control system for controlling the switching point of a device which operates in at least two modes of operation, provides for automatic modification of the error signal which controls the switching action of the device by processing in real time the error signal to generate a resultant signal representative of the variation of the error signal over a time period, and then employing the resultant signal to modify the effect of the reference signal from which the error signal is derived. The control system can be employed in a chemical analysis instrument to control the on-off operation of a heater which supplies heated air to incubate samples.

Abstract: A portable, manually operable device for preparing a monolayer film of a biological fluid sample or the like on a slide for microscopic examination. Said device includes a base for retaining the slide thereon and a spreader manually movable linearly relative to the base and slide in a pass which spreads a sample of the fluid on the slide into such a monolayer. Preferably, the spreader is constructed to be disposable.

Abstract: A transducer for measuring particles suspended in a fluid is disclosed. The transducer includes an elongated tubular member having a particle-free fluid conducting channel and an aperture for permitting the flow of a particle containing fluid into the fluid conducting channel. The size of the particles is measured by measuring the impedance variation of the particle containing fluid as it passes through the aperture. Spurious variations of the impedance caused by reentry of the particles into the region about the aperture is prevented by spacing the wall of the channel opposite the aperture so that the particle containing fluid impinges thereon after passing through the aperture and so that the particle-free fluid transports the particles away from the aperture before the particles reenter the region about the aperture.

Abstract: A method and reagent system is described for differential determination of three-populations of leukocytes (lymphocyte, monocyte and granulocyte), using an automatic counting system. The reagent system includes a blood diluent and lysing reagent. The blood diluent is an osmotically balanced aqueous solution of ingredients at a preselected pH for maintaining erythrocyte morphology, blood cell stabilizing, buffering and bacteriostatic action. The lysing reagent is a mixture of an aqueous solution of quaternary ammonium salts, which lysing reagent is added to the diluted blood under more mild conditions of concentration and at a slower rate than is current practice in order to obtain an unexpected volumetric modification of at least one of the three-populations of leukocytes, whereby volumetric differential analysis can be accomplished.

Abstract: An amplifier circuit having an input circuit of resistance and capacitance which is a.c. coupled to a source of pulses, and a feedback circuit of resistance and capacitance. The RC time constants of the input and the feedback circuits are made to be approximately equal at the time of pulse input in order to insure an output pulse flat base line without undershoot or overshoot.

Abstract: A pinch valve module comprising a housing, a cylindrical cavity formed in the housing, plural passageways leading from the cavity to the exterior of the housing and spaced about the cavity and a coaxial rotor rotatable within said cavity. The rotor has a diameter less than the diameter of the cavity defining a chamber between its outer wall and the inner cavity wall. Plural spaced pins are located within the chamber and are spaced about the rotor periphery. The rotor has unitary outwardly extending radial protrusions in the form of lobes extending into the chamber. Generally cylindrical tubular rollers or rings are loosely seated about selected ones of said pins within the chamber. Flexible conduits are threaded through said passageways and are disposed along arcuate sections of the chamber walls between the pins and the chamber wall.

Abstract: A liquid transfer rotary valve assembly capable of measuring and delivering at least a pair of different sample volumes in the microliter range along with a predetermined volume of diluent as a pair of different dilutions directed to different locations. The valve assembly provided herein includes a pair of stationary outer disc members and a movable inner disc member sandwiched therebetween, the facing surface portions being sealingly frictionally engaged. Each disc has an axial central passage to accommodate a spindle. An external hollow loop is provided on one of the stationary discs having a precise volume in the microliter range. A segmenting passageway is provided on the movable inner disc member. A source of sample is communicatively coupled through the other stationary disc to the segmenting passage which is arranged in series with the external loop.

Abstract: A tandem arrangement of sensing zones is established by alternately arranged electrodes and dielectric plates, each sensing zone has a particle sensing aperture, through which microscopic particles in an electrolyte suspension pass and electric current flows. The apertures are aligned. This tandem sensing zone arrangement improves the signal-to-noise ratio of a particle analyzing apparatus in which it is employed.

Abstract: Apparatus for monitoring chemical reactions occurring on a slide, cartridge or other reflective carrier in which the nature of the reaction is determined quantitatively by means of a change in color. The reaction products are illuminated by radiant energy of a known wavelength and the reaction is detected and/or monitored by the reflection of the radiant energy from the sample where the reaction is occurring. A plurality of samples carried on such slides is disposed in alignment in a circle or a line and a rotor or carriage carrying plural photometers or a single photometer producing plural beams at different wavelengths is moved relative to the samples, the beams being directed at the samples.

Abstract: A particle analyzer wherein a flow of liquid suspension, having individually entrained particles, flows along a predetermined path; a center pair of electrodes are positioned on opposed sides of the predetermined path: the center electrodes are energized to provide an electrical sensing field therebetween, two pairs of outer electrodes are positioned so that one pair is on each side of the center electrodes; the outer electrodes are oriented and/or energized so that their electrical fields bulge outward in the direction of the sensing field of the center plates to narrow the width of the sensing field along the predetermined path. Additionally, the field between the center plates can be focused in additional directions and the sensing electrode arrangement can be implemented in a flow cell, with or without an aperture, or on the surface of a substrate.

Abstract: Disclosed is an abnormal pulse detector for use with a particle analyzing apparatus of the Coulter.RTM. type for generating discrete particle pulses in response to liquid suspended particles passing through a sensing aperture, the abnormal pulse detector comprising: a bad pulse detector for generating a bad count pulse for each of the particle pulses which have a width that is either too long or too short, comparative pulse detector means for generating a comparative count pulse for each of the particle pulses or for each of the particle pulses not generating a bad count pulse, counter and comparator circuitry for counting the bad count pulses and the comparative count pulses and for obtaining the ratio of the bad count pulses to the comparative count pulses so as to indicate a alarm condition when the ratio reaches a predetermined, unacceptable level.

Abstract: This invention utilizes for stabilization of platelets a combination of iodoacetamide and an iminodiacetic acid or salt thereof, together with a compatible bacteriostatic agent, in an aqueous electrolytic solution which is maintained at a preselected range of pH and osmolality.In a preferred formulation, the stabilizing solution contains iodoacetamide, N-(2-acetamido)iminodiacetic acid and sodium penicillin. Ethylenediaminetetraacetic acid, or salts thereof, are optionally present as an additional ingredient.

Abstract: Disclosed is a monolayering device comprising a cell sensor arrangement for receiving a liquid suspension of cells and for controlling the number of cells passing through to an application vessel, a filter tape having the application vessel positioned thereabove at a first station, a vacuum source for sucking the liquid of the liquid suspension from the application vessel through the tape, a tape moving arrangement for moving the portion of the tape having the cells deposited thereon from the first station to a second station whereat a slide is positioned, and a sponge having a fixative therein mounted on a block for biasing the tape against the slide so that the cells will adhere to the slide.

Abstract: A particle analyzer for a sample suspension of particles originating in a container in which: a flow director is mounted between the container and a first chamber, a particle sensing aperture is mounted between the first chamber and a second chamber, a liquid sheath is introduced into the first chamber for hydrodynamically focusing the particles through the sensing aperture, an electrical current passes through the sensing aperture for generating impedance signals, the pressure drop is regulated across the flow director to assure a constant flow of the suspension through the flow director and the aperture, and the flow director is formed into an optical element for viewing the sensing aperture.

Abstract: Biological cell compositions are stabilized to preserve aldehyde functionality by formation of acetal, particularly cyclic acetal, primarily in order to prevent cell-to-cell crosslinking. The stabilized biological cells are particularly useful as human blood particle analogs in reference reagents employed in electronic hematology testing instrumentation.A process for preparing the acetal-stabilized biological cells employs reaction of polyaldehyde-treated biological cells with alcohol, preferably including 1,2 dialcohol, under acidic conditions; thereafter, the resulting product solution is adjusted to basic condition, stabilizing the acetal formation on the biological cells.