Abstract: A fixed angle centrifuge rotor body is constructed from compression molded composite material. The rotor body has a frustum shaped peripheral contour about a central spin axis between a base end and an apex end. The body has net shaped angled sample tube apertures defined in the rotor body extending from openings in the apex end adjacent the spin axis of the rotor body to bottom portions of the sample tube apertures more remote from the spin axis of the rotor body. The rotor body is formed from resin cured about discontinuous composite fiber with the major axis of the discontinuous fiber disposed normal to the spin axis of the rotor body interior of the rotor body. The resin cured discontinuous composite fibers exceed 40 weight percent of the cured rotor product and have no visible layering between respective fibers. The resin cured discontinuous composite fibers have minor vertical excursion parallel to the spin axis of the rotor and relatively no kinking along their respective lengths.

Abstract: A high efficiency centrifuge rotor for rapid separation of particles suspended in a liquid is disclosed. The rotor features one or more cavities disposed at a compound angle to provide for rapid separation of particles suspended in a liquid while minimizing distortion of the separation interface or separation barrier, if any, within the sample container.

Abstract: A fixed angle rotor and method of manufacture of a fixed angle rotor has a frustum shaped rotor having rounded surfaces reinforced by filament tow windings against both vertical and horizontal forces generated during centrifugation. A so-called "high speed" rotor has a bottom composite disc, a top composite disc, and a frustum shaped hollow fiber reinforced molded insert between the respective discs having a stepped exterior surface. An "ultra speed" rotor has a bottom composite disc, a top composite disc, and composite discs therebetween defining a stepped exterior surface. In both cases, these exterior steps have surfaces which capture the windings to the exterior of the rotor. A first class of individual fiber windings about the rotor is applied having a vertical reinforcement component parallel to the spin axis and normal to the laminate layers.

Abstract: The method of distributing biological material suspended in a liquid sample comprises the steps of directing the liquid sample into a centrifuge sample chamber along a tortuous path of vertically spaced surfaces in the chamber, each of the surfaces being in communication with a discharge opening from the chamber to one surface of the microscope slide, continuing to direct the sample into the chamber until some of the biological material is deposited on portions of at least one of the surfaces and centrifuging the sample chamber whereby the biological material on each of the surfaces of the chamber passes through the discharge opening on the one surface of the slide.

Abstract: The present invention relates to an applied load accepting band for a centrifuge rotor that is configured such that, while rotating, the applied loads on the band are balanced by the tension in the band, so that during rotation the band is subjected only to a tensile force.

Abstract: The present invention relates to an improved device and method for separating a first component in a solution from a second component in the solution. The device comprises a centrifuge for applying centrifugal force to the solution and at least one transducer for emitting a sonic energy force such as an ultrasonic wave into a container of the solution while the centrifuge is rotating. The method of the present invention broadly comprises the steps of applying a centrifugal force to the solution to separate the first component from the second component and simultaneously applying a sonic energy force to the solution to speed up the separation of the first component from the second component. A tool for removing transducers from the device is also disclosed.

Abstract: A fixed-angle centrifuge rotor fabricated from fiber-reinforced composite material includes a rotor plate, composite tube holders, and a hub to attach the rotor plate to a centrifuge. The rotor plate has counterbored through holes with each counterbore defining an annular step. The tube holders are cylindrical in shape and are mounted to the rotor plate in each of the counterbored through holes. Each tube holder has an circumferential flange that mates with and is bonded to the annular step in a counterbore of the rotor plate.

Abstract: A shell-type centrifuge rotor has a sample container support sleeve extending through the cavity in a plate. The sleeve has at least two slots which define at least one resilient flange pivotally deflectable about a pivot axis to hold the sleeve in a fixed relationship with respect to the plate. In one embodiment both slots extend axially along the sleeve. In an alternate embodiment a first one of the slots extends axially along the sleeve and the second one of the slots extends circumferentially along the sleeve. In a modification to the alternate embodiment a second circumferential slot is formed in the sleeve in generally parallel relationship to the first circumferentially extending slot.

Abstract: A centrifuge rotor has a central hub with a mounting recess therein, a ring disposed concentrically about the hub, the ring having a plurality of cavities formed therein, and a relatively thin web connecting the hub and the ring. The web defines a localized region which exhibits a stress therein that is greater than the stress present in any other portion of the rotor when the rotor is operating at the predetermined operating speed, so that, over operation time, the probability that rotor failure will occur only in the web is enhanced. The cavity ring has an annular rim with an upper surface having a predetermined reference line defined thereon. A portion of the upper surface of the rim defined relative to the reference line is relieved. The radial location of the relieved portion of the upper surface with respect to the reference line is governed in accordance with the axial position of the web with respect to the center of mass of the ring.

Abstract: A separator float has a generally cylindrical body and a water swellable band having a selected outer diameter fitted circumferentially around a portion of the generally cylindrical body. The water swellable band is made of a water swellable material so that upon being exposed to water the water swellable band swells to a greater outside diameter. The separator float is preferably used in a blood collection tube and has a specific gravity between specific gravities of a light phase and a heavy phase of the blood. After the blood has been collected and centrifuged the separator float moves to a position between the light phase and the heavy phase and the water swellable band is exposed to water in the blood causing the band to swell and create a seal. Thereafter, the serum or plasma as well as white blood cells, lymphocytes, monocytes and platelets can be removed from the blood collection tube.

Abstract: The cover for a fixed angle centrifuge rotor has an array of container support surfaces depending from the lower surface thereof. Each support surface is substantially cylindrical in configuration and has an axis associated therewith. Each container support surface is associated with a respective one of the cavities formed in the rotor body. In the most general case, when the rotor cover is attached to the rotor body, the axis of each container support surface lies in the same common radial plane as do the axis of the cavity with which the support surface is associated and the axis of rotation. In the common radial plane, the axis of a support surface is inclined at a predetermined angle with respect to the axis of rotation. The axis of the support may further be arranged to lie in parallel relationship to the axis of the cavity with which it is associated, or may define a predetermined angle with respect thereto.

Abstract: The present invention is a collection assembly useful for collecting small quantities of blood. The assembly comprises a container with an integral lip for facilitating collection of the blood and a cap suitable for enclosing the container. The assembly further comprises a sealing arrangement for securing the cap to the container using a protrusion on the cap and a locking ring on the container, wherein the container includes a riser below the locking ring that interacts with the protrusion on the cap to unsecure the cap from the container, when the cap is rotated on the container.

Abstract: A centrifuge instrument and a rotor therefor which is loaded with sample containers automatically by gravity through an opening in a cover located over a core and, subsequent to centrifugation, is unloaded automatically, again assisted by gravity, through an opening in a floor disposed beneath the core. A sample container loading arrangement is provided to hold a plurality of sample containers and to individually present sample containers to the rotor.

Abstract: An applied load accepting band for a centrifuge rotor is configured such that while rotating, the applied loads on the band are balanced by the tension in the band, so that during rotation the band is subjected only to a tensile stress.

Abstract: A system for centrifugation of samples includes at least one carrier, which is provided with a plurality of elements connected with each other by joints and having each an uptake for receiving a sample to be centrifuged, and a rotor for supporting the carrier, with the elements being arranged, in a centrifuged position of the elements, along a circle having its center lying on the rotational axis of the rotor.

Abstract: The present invention is a collection assembly useful for collecting small quantities of blood. The assembly comprises a container with an integral lip for facilitating collection of the blood and a cap suitable for enclosing the container. The assembly further comprises a sealing arrangement for securing the cap with the container and a cam follower within the cap that interacts with the integral lip of the container to unsecure the cap from the container.

Abstract: The present invention is directed to a centrifuge rotor having a rotor body and an associated lid. A skirt with a radially outwardly facing surface thereon depends from the radially outer peripheral undersurface of the lid. A contoured cut-out is formed in at least the radially outwardly facing surface of the skirt. The undersurface of the lid radially outwardly of the skirt also has a generally contoured cut-out formed therein. The contours of the cut-out portions meld together and cooperate to define a smoothly curved concave undercut region below the periphery of the lid that accepts a lifting implement, whereby lifting or lowering of the rotor may be facilitated.

Abstract: A centrifuge construction is disclosed in which a centrally located stator directly drives a peripheral ring shaped centrifuge rotor. In the preferred embodiment, a centrifuge drive is disclosed which includes a stationary, central and usually cylindrical stator having stationary electrical windings for generating a rotating and driving magnetic field. The ring shaped centrifuge rotor is supported by at least one bearing relative to the stator and includes a large central aperture defined by the inside of the ring which enables the rotor to fit over and rotate about the stator. At portions of the rotor adjoining the stator, the rotor is constructed from materials which are entrained by the rotating magnetic field. The centrifuge rotor containing samples undergoing centrifugation is directly driven from the stator by entrainment of the rotor with the rotating and driving magnetic field generated from the electrical windings of the stator.

Abstract: A lab centrifuge with a rotor carrying vessel supports and a motor with a vertical shaft driving said rotor into rotation, the stator associated with said rotor being supported by elastic supports on a centrifuge base. A shutoff device controls the motor which it shuts off in response to a signal generated by a component affixed to the stator and a component affixed to the base when the stator deviation taking place is found to exceed or match the maximum admissible threshold imbalance. One of the two components is a field generator generating a constant field and the other component is a field intensity detector connected to an analyzer which, upon limit changes in field intensity caused by the deviation, implements shutoff.

Abstract: A rotor assembly for use in a centrifuge is provided including a rotor body having a plurality of apertures for holding fluid containers. An impervious cover fits tightly on the rotor body to provide a seal for the rotor to prevent the escape of any sample from the rotor. Further, a mechanical connection system permits the rotor to be connected to and disconnected from a drive motor while the cover is sealing the rotor.

Abstract: A rotor adapted for use in a nonevacuated chamber has a liquid containment annulus having a capacity V.sub.C. The rotor also has a predetermined number N of liquid-capturing holes, each hole being sized and inclined such that it is able to capture therein a predetermined volume V.sub.H of liquid that may escape from a container while the rotor is rotating. At least some portion of the mouth of each hole lies radially outboard of a circular locus defined by corresponding points on each of a plurality M of container-receiving cavities in the rotor. The number N of holes and the volume V.sub.H of each hole satisfies the relationship:N.multidot.V.sub.H +V.sub.C .gtoreq.n.multidot.V.sub.Rwhere n is an integer less than or equal to M and V.sub.R is the volume of liquid which is liberated in the event of rupture of the container received in a cavity.

Abstract: Improved cytology centrifuge apparatus includes single or multiple well cell concentrators for being rotated by a centrifugal spinner. A rotor is removably supported by the spinner for rotation and is adapted to receive two or four cell concentrators. The rotor supports the cell concentrators in an unrestrained manner, thereby enhancing the ease of use and flexibility of the apparatus. Each cell concentrator includes a chamber having a top surface in which at least one fluid receiving aperture is disposed and a front surface in which at least one fluid expulsion aperture is disposed. A backing plate is provided with protruding top and bottom edges to vertically align a microscope slide with the chamber so that the fluid expulsion aperture is adjacent to a central portion of the slide. Retention clips secure the chamber to the backing plate with the slide sandwiched therebetween in horizontal alignment.

Abstract: The present invention relates to methods of enriching hematopoietic progenitor cells from body fluids. In particular, it relates to the use of a cell-trap centrifugation tube containing a gradient solution adjusted to a specific density to enrich for CD34.sup.+ cells from apheresed blood. The tube allows the desired cell population to be collected by decantation after centrifugation to minimize cell loss and maximize efficiency. In addition, the method can be further simplified by density-adjusted cell sorting which uses cell type-specific binding agents such as antibodies and lectins linked to carrier particles to impart a different density to undesired cell populations allowing the progenitor cells to be separated during centrifugation in a more convenient manner.

Abstract: A cytology chamber comprises a sample holding portion, a funnel through which the fluid sample is directed into the holding portion of the chamber, a generally flat, solid flange member defining an upright support surface and having an opening through the flange member in communication with the holding portion, and baffle plates in the holding portion define a tortuous path of flow for collecting at least some of the sediment in the fluid prior to reaching the bottom of the holding portion.

Abstract: A cytocentrifugation device of the type disclosed by the copending Stokes-Quirante U.S. application Ser. No. 07/788,310 (U.S. Pat. No. 5,252,228 on Oct. 12, 1993) is improved by the provision of elongate, rounded projections on and protruding from the clamping face of the delivery conduit flange at the delivery end of such conduit and the flattening of the otherwise rounded and flange contacting end faces of the clamping arms. Further improvements include a floating mounting for the clamping arms so as to ensure even clamping of the annular area of the absorption pad marginal to the absorption pad opening confronting the cell deposition area of the microscope slide that is otherwise covered by the absorption pad, and the provision for positively, properly aligning the several items to be clamped together during operation of the cytocentrifuge apparatus.

Abstract: The present invention is a collection assembly useful for collecting small quantities of blood. The assembly comprises a container with an integral lip for facilitating collection of the blood and a cap suitable for enclosing the container. The assembly further comprises a sealing arrangement for securing the cap with the container and a cam arrangement for unsecuring the cap from the container.

Abstract: An assembly for transferring rotation from a centrifuge drive system to a centrifuge rotor includes a hub that is connected to the drive system for rotation about an axis. A sleeve member is attached to the hub in a position to support the centrifuge rotor. The sleeve member is formed of a material having a low coefficient of friction and is positioned to reduce the likelihood of rotor-to-hub lock. The resistance of the sleeve member to wear and to the absorption of foreign matter are also important in the selection of a material for forming the sleeve member. An acetal-based compound is preferred. By connecting the sleeve member to the hub such that the exterior surface of the sleeve member is raised relative to the surface of the hub, rotor-to-hub contact is reduced, thereby further reducing the risk that the rotor and the hub will become locked to one another.

Abstract: A device for centrifugally separating a sample includes a housing which defines an enclosed chamber from which gas is evacuated via an evacuation port protected by a spinning rotor. The evacuation port is preferably located proximate to the axis of rotation of the rotor and within the interior of the rotor. A drive shaft connects the rotor to a motor positioned outside of the chamber. An annular sleeve having an inside diameter greater than the diameter of the shaft extends coaxially along the drive shaft into the chamber. The outlet of the gap between the drive shaft and the annular sleeve defines the evacuation port. A hub is fixed to the upper end of the drive shaft and includes a downwardly depending skirt that has an inside diameter greater than the outside diameter of the annular sleeve. Gas evacuation from the chamber is initially in an upward direction along the gap between the hub skirt and the sleeve and in a downward direction from the evacuation port to a vacuum pump.

Abstract: A centrifuge rotor which makes use of a composite ring to support a segmented core body. The core body is segmented into sectors. The core segments are slidably coupled to a hub in a manner such that they can move radially relative to the hub upon centrifugation with substantially no radial tensile stress build up in the coupling between the hub and the core segments and within the segment cores. In another aspect of the present invention, to augment the segmented core rotor, hybrid composite sample holders are utilized to further improve overall strength-to-weight of the rotor. The holders comprise a metal portion and a fiber composite portion integrally molded.

Abstract: A centrifuge (10) for spinning blood sample tubes (14) has a conical rotor head (17) rotated within a cavity defined by an upwardly open annular trough (39) and a domed lid (50). The tubes (14) are inserted into transparent plastic tube holders (48). The holder top ends (60) are funnel-shaped to capture spillage and enable manual gripping. The trough has oppositely sloping walls (40, 41) and holder bottom ends (59) are exposed for ready viewing below the head bottom edge. A reader station (15) includes a pointer (80) with a lens (86) that has hairlines (87) for aligning the pointer over the spin tube (14a) to enter data on the red cell/plasma interface. The lines (87) are spaced to match the diagonal appearance of the interface. An interlock assembly includes a solenoid operated shuttle arm (108) that blocks movement of a pin (95) out of a bore (94) in a lid tab (92), unless motor (23) is deenergized.

Abstract: A centrifuge tube adapter for supporting a closed tube in a cavity of a vertical angle centrifuge rotor includes an inboard and an outboard adapter segment. A hinge connects the segments and supports relative pivotal movement of one segment with respect to the other. The hinge comprises a pair of axles formed at the lower end of one segment and a pair of trunnions formed at a corresponding location on the other segment. The inboard segment has a flange and the outboard segment has a channel therein sized to receive the flange. The flange has serrations thereon.

Abstract: The present invention is directed to a floating cap or spacer and centrifuge tube assembly which provide adequate resistance to the deforming forces exerted on it. The exterior wall of the tube stem is provided with an annular ridge and the support spacer is provided with an annular groove which mates with the ridge on the tube stem to form an interlocking coupling.

Abstract: The present invention is a collection assembly useful for collecting small quantities of blood. The assembly comprises a container with an integral lip for facilitating collection of the blood and a cap suitable for enclosing the container. The assembly further comprises a sealing arrangement for securing the cap with the container and a cam arrangement for unsecuring the cap from the container.

Abstract: A fixed-angle centrifuge rotor fabricated from fiber-reinforced composite material including a composite rotor plate, composite tube holders, and a hub to attach the rotor plate to a centrifuge. The rotor plate has counterbored through holes with each counterbore defining an annular step. The tube holders are cylindrical in shape and are mounted to the rotor plate in each of the counterbored through holes. Each tube holder has an circumferential flange that mates with and is bonded to the annular step in a counterbore of the rotor plate.

Abstract: An adapter for a centrifuge tube comprises two segments that may be hinged along a hinge axis that extends perpendicular to the axis of the adapter.

Abstract: A self-balancing apparatus for a centrifuge is disclosed which employs two arcuately movable counterweights. The centrifuge has a plurality of receptacles for receiving one or more assay cartridges. Control apparatus in the centrifuge determines the location and number of received cartridges. Desired counterweight positions are then calculated which will substantially balance the centrifuge. The counterweights are moved into these positions prior to the centrifuge being operated at high speeds.

Abstract: A cytocentrifugation device, rotor, and apparatus are improved by providing the device with a plurality of liquid-receiving chambers arranged serially along and opening into an elongate conduit leading to and terminating within a filter-pad-holder so that a filter-pad-prewetting liquid can be passed along such conduit and into a liquid-flow opening of a filter pad held by such holder in advance of passage along said conduit and through such liquid-flow opening in the filter pad of a cell-carrying liquid sample during a centrifugation run of the apparatus. Retention of prewetting liquid in the filter pad around the sample liquid flow helps to prevent loss of cells to the filter pad. Various other structural modifications of the cytocentrifugation device and filter pads used therewith also help to prevent loss of cells to the filter pad.

Abstract: A centrifuge basket shell formed by winding fiber-reinforced resin tape in a helical pattern over a thin shell plate which contains a plurality of holes for the passage of liquid therethrough, perforations being formed in the helix pattern of the wound tape by means of respective hollow ferrules connected rigidly to a cylindrical part of the shell plate, so as to enable liquid which passes through said holes in the shell plate to pass also through the helices of wound tape without increasing the stresses induced therein by rotation.

Abstract: A shell-type centrifuge rotor includes a body member having an upturned lip and a plate having a skirt portion attached to the body. The skirt portion has a groove therein that overlies the lip on the body. The groove defines a relatively high stress region of likely failure of the rotor. A seal is disposed in the groove, the seal extending between the plate and the lip. Failure of the rotor in the vicinity of the groove in the skirt portion at a first operating speed defining an opening through which a portion of the seal may protrude. The protruding portion of the seal generates a force tending to lower the speed of the rotor below the first operating speed. The radially inner surface of the seal ring is inclined toward the axis of rotation. The radially inner boundary surface of the groove is parallel to or inclined radially inwardly toward the axis of rotation.

Abstract: A fixed-angle centrifuge rotor fabricated from fiber-reinforced composite material includes fibers for reinforcing radially outer portions of the cell holes in a direction transverse to the laminated layers of the rotor core. In one embodiment, the reinforcement fibers are in a reinforcement shell of fiber-reinforced composite material wound over the periphery of the rotor core. In another embodiment, the reinforcement fibers are in a reinforcement cup of fiber-reinforced composite material bonded into each of the cell holes. In a third embodiment, the reinforcement fibers are in a formed region of the laminated layers to orient the fibers therein obliquely to the rotor axis.

Abstract: A centrifuge rotor head has a hollow frusto-conical housing with parallel inner and outer, upwardly and inwardly inclined walls joined at top and base ends by top and bottom annular flanges, and closed at the top by a central horizontally extending disc portion. The top flange is interrupted at equiangularly spaced intervals by circular openings which, together with an internal annular chamber, present steep angled cavities making angles of about 20.degree. with the rotor cone axis. The housing is capped at its upper end by a circumferentially-extending crown-shaped ring which has a plurality of upwardly and inwardly inclined projections located radially outward of the openings. The projections support the exposed upper ends of tubes placed in the cavities, to guard against neck breakage and stopper dislodgement during spinning.

Abstract: A centrifuge rotor lid assembly which includes a handle which allows convenient handling of a centrifuge rotor and facilitates releasing the lid from the rotor after centrifugation. In one embodiment, the lid is provided with a lid knob and a spindle knob in a coaxial sliding arrangement. The lid knob is used to tighten the lid on the rotor body and the spindle knob is used to tighten the rotor to the centrifuge drive spindle. The upper end of the inner knob is provided with a handle which extends perpendicular to the axis of the knob. This handle is used for lifting the rotor after the spindle knob has been unscrewed from the spindle and for unscrewing the lid knob. The lower end of the spindle knob has a pin which cooperatively engages the lower end of the lid knob when the spindle knob is lifted from the rotor and is turned in a direction to unscrew the lid knob.

Abstract: A centrifuge comprising a rotor drive shaft including a flexible shaft surrounded by a sheath. The flexible shaft and the sheath are both rotationally secured at a first end. A second end of the flexible shaft extends beyond a second end of the sheath. A head is adapted to receive a rotor of the centrifuge. The head is rotationally secured to the second end of the flexible shaft. A member damps and limits a radial displacement of the flexible shaft with respect to the sheath. The damping and limiting member comprises an annular seal made from an elastic material. The annular seal is axially arranged about the flexible shaft and the sheath at the same level as and close to the head. A skirt is formed on head and surrounds the second end of the sheath. The skirt has an internal annular groove for receiving damping and limiting member. The skirt includes a lower transverse wall limiting the annular groove.

Abstract: A vial holding a material such as an organic liquid-containing biological specimen is received in the receptor of a holder assembly, the assembly further including a centrifugal valve. The holder is mounted on a rotor in a centrifugal vacuum concentrator and the specimen is then subjected to a treatment such as drying in the vacuum chamber. Vapor from the drying vents into the concentrator vacuum chamber, the centrifugal valve which is a normally closed component opens due to imposition thereon of centrifugal force created during and attending rotor speed above a certain RPM. At completion of the treatment and before the rotor falls from its certain RPM, a dried material protective gas blanket can be flowed into the vial, the valve closing to seal the vial and protected contents when RPM of the rotor falls below the certain RPM.

Abstract: A tube for use in a pelleting centrifuge rotor is characterized in first aspect by a first, acute, corner and a second, obtuse, corner defined in the lowermost pelleting region thereof. The corner defined by the acute angle lies a greater axial distance from the mouth of the tube than the corner defined by the obtuse angle. In a second aspect the tube the interior of the tube has a constricted region with a guide adjacent thereto. The guide channel is sized to accept a supernatant removal implement.

Abstract: An adapter for a centrifuge tube comprises two adapter segments, each of which has an exterior surface and a mating surface thereon. Each segment has a pair of indentations in the mating surface. When the segments are joined along their mating surfaces the indentations cooperate to define a pair of recesses therein. Each recess so defined is configured to surround totally a centrifuge tube disposed therein. Each recess has an axis extending therethrough, with the axes of the recesses being collinear. The collinear axes of the recesses are aligned parallel to the axis of rotation of the rotor, and preferably also align collinearly with the axis of the rotor cavity in which the adapter is disposed. Each adapter segment is fabricated of a material that has sufficient strength to withstand the vertical forces created by the pressure of a liquid under centrifugation.

Abstract: A container assembly is provided for collecting capillary blood from a lanced wound. The container includes an integral lip for facilitating collection from the wound with the entire length of the container from lip to curved closed end being substantially the same large diameter for rapid collection before coagulation. The container includes an annular integral skirt enclosing the rounded bottom of the container to provide an annular stable surface for maintaining the container upright on a flat surface to facilitate subsequent examination of the collected blood. A cap for the assembly includes an annular space for receiving the top edge of the container in sealing engagement. This same annular space in the cap receives the annular bottom surface of the container skirt to join the two parts together when the container is open. The cap, in turn, includes an annular skirt for holding the open assembly in stable erect position on a flat surface.

Abstract: A centrifuge rotor is characterized by a portion of the undersurface thereof being removed to define a predetermined number of bosses, each with a sample receiving cavity therein. A relatively thin skirt portion extends between at least one pair of adjacent bosses. The skirt portion has defined thereon a localized region which exhibits a stress therein that is greater than the stress present in any other portion of the rotor when the rotor is operating at the predetermined operating speed. The skirt may have a weight thereon. The weight may be either separate from or formed integrally with the skirt. Additionally or alternatively, a stress riser, in the form of one or a pair of hole(s), notch(es) or groove(s), may be defining on the skirt. Over operation time, the probability that rotor failure will occur only in the localized region of the skirt is enhanced.

Abstract: A measurement device is provided for determining relative proportions of at least two materials forming a liquid and having different densities and different responses to light. A transparent capillary size cuvette tube confines the sample liquid, and is attached radially on a rotor wheel, preferably by a holder which seals an outer end of the tube and provides a package for manipulation of the tube without exposure to the sample. A motor controlled by a processor turns the rotor wheel, separating the materials by their densities. A linear light source illuminates the tube, and a linear array of photosensors defining pixels produces a signal which varies where the different materials abut. The pixels are counted, to locate the stratum between materials and the result is displayed as a percentage of total volume, suitable for hematocrit measurements. The cuvette tube has a fin for assisting in manipulation, is shaped as an elongated lens, and is cut to a spherical end surface to assist in sample collection.

Abstract: A centrifuge rotor and method for gradient density separation which supports a generally cylindrical volume of sample solution with its axis inclined to the spin axis at an angle which is optimized for maximum separation efficiency while reducing contamination by undesirable centrifugates upon reorientation of the desirable centrifugates. .Iadd.The sample solution is contained in a centrifuge tube which is closed at its top end by a top portion which is supported by a support cap. The undesirable centrifugates are pelleted to the end corners of the inclined centrifuge tube. The rotor and method are particularly adapted, for example, for separation of nucleic acid into plasmid DNA and chromosomal DNA by density gradient centrifugation. .Iaddend.The optimum angle is determined based on the relationship .theta.=Tan.sup.-1 (D/15L).sup.0.5 where D and L are respectively the diameter and length of the cylindrical volume of the sample solution and .theta. is the angle of inclination.