Beckman Instruments, Inc.

Thomas D Sharples

Donald E Stephens

Alireza M Piramoon

Kenzo Ishimaru

Robert J Ehret

Douglas Howard Durland

John T Taylor

Mark J Cowell

Stephen E Little

Mark L Lewis

A method and system of identifying a rotor of a centrifuge employ an approach that uses two tiers of model selection. Firstly, the moment of inertia of a rotor is calculated for a first measured acceleration. The indication of moment of inertia is utilized to disqualify a number of rotor models and to select a subset of models. In a second tier, windage power of the rotor is calculated in a manner that isolates windage from inertial drag. In one embodiment, drive torque is measured with the rotor operated at a high constant speed. Alternatively, windage is calculated using data obtained during a second measured acceleration. The accuracy of the computation is enhanced by taking into account the moment of inertia as one form of resistance to the second acceleration. Based upon the indication of windage power, at least one rotor model within the subset is disqualified. Upon identification of the rotor, the centrifugal process can be maintained at a maximum safe speed. Moreover, a refrigeration offset circuit is controlled to provide a dynamic temperature correction with changes in windage power.

Centrifuge rotor identification and refrigeration control system based

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. 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.

Optimum fixed angle centrifuge rotor

A centrifuge hub-rotor drive is disclosed in which a rotor has an internal recess that fits over and interfaces with a hub. The hub has a skirt with a curved outer periphery that interfaces and contacts internal walls of the rotor which define a tapered section of the recess. The curved outer periphery of the skirt ideally meets the internal tapered walls of the rotor along a curved contact band. The outer periphery of the skirt is taken from a portion of a spheroid, regular, oblate or prolate.

Centrifuge drive hub

A slotted retaining plate for use in a tubular reactor within an analytical system. The reactor contains inert packed material which provides for the necessary flow path length for a fluid stream entering the reactor. The retaining plate is extremely thin and has an array of slots which permit the necessary flow of the stream through the reactor, but retain the packing material within the reactor. The design of the slot array in the retaining plates essentially eliminates any possible impediment to the stream flow. The slots are adjustable to provide more flexibility in slot size control to allow use of smaller packing particles within the reactor and improve the instrument resolution in, for example, an amino acid analyzer.

Method of forming slots in a material-retaining plate for a packed

A swinging bucket centrifuge rotor including seating surfaces having shapes which cause buckets seating thereon to be relieved of side loading forces. Each bucket is symmetrical and is pivotally supported by bucket pins that rest in respective spring-loaded carrier assemblies. The spring constants of the springs of the carrier assemblies are selected so that the leading edge of each bucket bottom rests upon a curved surface and clears the respective seating surface before the trailing edge thereof contacts the same. The resulting bucket orientation assures that, upon seating, each bucket rotates until its bucket pins lift slightly off of the surfaces of the respective carrier assemblies.

Swinging bucket rotor having improved bucket seating arrangement

A torque-transmitting connector is disclosed which fits between a spindle and the walls of a bore in a rotating member. The connector includes a sleeve encircling the spindle and two flanges located at its opposite ends. Each flange is initially frustoconical, and is forced into substantially a disc shape to grip the spindle and the wall of the bore. The flange at the bottom of the bore is flattened first by a small diameter punch acting against the other end of the sleeve; and the other flange is then flattened by an annular punch encircling the small diameter punch.

Small diameter shaft connection

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.

Packed column thermal reactor for an analytical instrument

A sealed bowl rotor having a transparent lid for easy visual checking of rotor contents. The lid has sealing means that automatically creates a seal which prevents the escape of liquid samples from within the rotor when the lid is placed on the rotor. The rotor design prevents the application of any possible hydraulic loading on the transparent lid. The installing/removing mechanism on the lid provides the capability for removal of the lid after the centrifugation run without disturbing the contents of the samples within the rotor.

Aerosol resistant bowl rotor

A method of closing or sealing a filler passage formed in a neck or stem protruding from the small access opening in the upper end of a substantially closed centrifuge tube. The neck is formed of a readily fusible material and a heat conductive cap member is positioned over the open end portion of the neck closely confining it therein. Heat and pressure are applied to the cap causing progressive portions of the neck to melt and fold into the filler passage where it forms a molten mass within the filler passage above the access opening to the tube. Heat and pressure are removed, permitting the cap to cool and the molten mass to solidify completely sealing or filler passage of the centrifuge tube. The cap is then removed and the centrifuge tube is fully prepared for centrifugation.

Method and apparatus for sealing centrifuge tubes

A method and apparatus for layering a liquid sample onto a support liquid through a narrow filler passage in a neck protruding from the opening in a substantially closed, flexible centrifuge tube by supporting the tube with its liquid support contents in an upright position, attaching a funnel shaped container to the neck of the tube, applying a squeezing force to the flexible tube to reduce its internal volume thereby forcing the liquid contents into the neck thereof to form a meniscus adjacent the opening of the filler passage, adding a sample liquid into the funnel shaped container above the filler opening and in contact with the meniscus of the support liquid, and releasing the squeezing force from the tube allowing it to return to its normal volume thereby drawing the sample into the tube layered on top of the support liquid.

Layering a liquid sample onto centrifuge tube liquid contents

An automatically controlled liquid dispensing system including a reagent dispenser adapted to function as an intermediate container for dispensing relatively small controlled volumes of liquid to an associated receiving system in a continuous 'demand' mode, this dispenser being indirectly monitored to be automatically and continually replenished after liquid is withdrawn therefrom, using a simple photoelectric liquid level monitor system including a fail-safe overflow control arrangement.

Liquid head control system

A valve construction in the form of a 'flex-finger' or flexible stem valve is provided for handling substances which are highly corrosive or very active chemically. The valve body, valve seats, a valve ball and flexible finger or flexible valve stem are all composed of chemically resistant material. The flexible stem has an outer end secured in the valve body against rotation with a fluid tight joint and an inner end for actuating the 'ball'. The flexible stem is composed of material which is sufficiently resilient so that it may be caused to travel in a circular or orbital path carrying or actuating a 'ball' or other attachment into and out of engagement with the valve seat or seats. For causing such motion the flex stem is made hollow but with the lower end closed to prevent entry of fluid from a valve port, and a bent operating rod is mounted within the hollow space in the flexible stem with a slip fit so that rotation of the outer end of the bent operating rod serves to cause orbital movement of the inner end of the flexible finger without twisting or rotation thereof.

Flexible stem valve

An arrangement for the controlled delivery of liquid reagent is shown wherein a reservoir vessel for storing the liquid in volume is coupled to replenish a 'vestibule vessel' provided for intermediate storage of the liquid enroute to the delivery point and for pneumatic propulsion thereof, the liquid being pneumatically driven from reservoir to the vestibule through a unidirectional check valve.

Vestibule valve reagent dispenser

A small ball valve for chemically active materials is provided which does not require the strength of metal parts and which permits the use of brittle material such as glass or ceramic as well as materials such as fluorocarbon polymers and polytetrafluoroethylene which are resistant to the action of chemically active fluids. A free-floating construction is provided without requiring a stem packing gland and permitting the stem to be integral with the ball. Identical sealing rings are provided with clamping screws which press the sealing rings inward against the ball and outward against the openings in the valve body, the diameter of the valve stem being smaller than the opening in the sealing ring and clamping screw therefor so that the portion of the ball surrounding the valve stem may also float freely under the sealing means with the seal around the ball stem being against the ball itself instead of against the valve stem. For reinforcement of the valve body or to permit the use of the valve when the controlled fluid is under high pressure a metal reinforcing ring may be fitted around the valve body.

Ball valve

A light beam is passed through a cuvette, through which flows liquid to be analyzed optically for concentration of color reacted amino acids. The emergent beam is directed through a series of dichroic beam separators and pass band filters to produce three beams of substantially three different wavelengths. Photoelectric detectors produce electrical signals corresponding to each of the three wavelengths. Two of the signals are characteristic of the substance to be detected. The third is subtracted from the other two wavelength signals to produce a pair of output signals from which base line noise has been substantially eliminated.

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Atherton, CA, United States of America

Thomas D Sharples