Abstract: A process and apparatus for predicting the time and position dependent concentration of macromolecules of differing species in a gradient forming solution during centrifugation is disclosed. A mathematical model of the time dependent behavior of gradient forming solutes in a centrifugal field, based upon the underlying physical principles governing sedimentation and diffusion is formulated. The simplifying approximation is made that the wall effects may be ignored, and that the transport of solute may be treated as a one dimensional process with forces dependent only upon the radial distance. A sedimentation diffusion (Lamm) equation in one dimension is numerically integrated. The sedimentation diffusion equation (Lamm equation) for each macrosolute is solved concurrently with that for the gradient forming solute, utilizing the experimentally based density dependent sedimentation coefficient. The equations are solved for incremental time periods for the centrifuged samples in successive radial segments.

Abstract: A breakaway base for use with an ultracentrifuge rotor wherein the base is designed to fracture when the rotor is above a specified speed so that the rotor will disengage from the drive spindle of the centrifuge. The base has cutout areas to establish a high stress region that is designed to fracture above a specified rotor speed. The cutout areas are designed to receive lugs projecting from the bottom of the rotor. The cutout areas have slotted ledges through which fastening bolts connect to the lugs on the rotor. The fracture of the base in the high stress region in conjunction with the slotted ledges will result in the base fracturing into two parts which will cause rotor disengagement from the drive spindle of the centrifuge and prevent the rotor from spinning at a greater speed.

Abstract: A centrifuge rotor is claimed which comprises a rotor having a plurality of radially extending arms, having a construction to matably receive a pin structure within a recess formed in the upper surface of the rotor, to support the pin structure against loads generated by centrifugal force without stressing a fastener. In assembly, the pin structures permanently mount trunnions for receiving a sample container, for pivotal movement, in a manner such that the trunnion and sample container cooperate to resist stresses and deformation caused by centrifugal loads.

Abstract: A swinging bucket centrifuge rotor having a plurality of cavities spaced about its vertical axis and extending entirely through the rotor. Each cavity is adapted to receive a bucket supported by a hanger rod. The mounting of the bucket is such that the bucket can pivot or swing from a vertical to a horizontal position during operation. Each cavity is provided with a slot, which extends along the underside of the rotor, from the cavity to the periphery of the rotor. The slot has an upper surface adapted to receive the bucket when the bucket is in the horizontal position. A pair of opposed grooves extend partway down the wall of the cavity whereby the ends of the grooves each form a ledge to support an end of the hanger rod by which the bucket is pivotally suspended.

Abstract: A fluid-containing means for each bore of a centrifuge rotor is disclosed which combines a self-capped tube and a floating cap resting on the top of the tube and arranged to resist deformation of the tube by the centrifugal forces developed therein. The floating cap has an annular skirt which engages the top of the tube and which is sufficiently thick in cross-section to prevent deformation of the floating cap. The floating cap is formed from a relatively light plastic, having a density less than that of the centrifuged fluid, thereby preventing bottoming of the floating cap in the bore in the event of rupture of the tube.

Abstract: A modular spacer concept is disclosed for use in centrifuge bores. The arrangement is such that various sizes of tubes are available to allow for different amounts of fluid which may be inserted therein for centrifugation. A plurality of substantially identical spacers are provided, each of which has an effective length equal to a predetermined standard difference in tube sizes. The lower surface of each spacer has a concave center portion adapted to fit the convex center portion of the upper surface of a tube, and the upper surface of each spacer has a convex center portion adapted to fit the concave center portion of the lower surface of a substantially identical spacer.

Abstract: This invention relates to a swinging bucket centrifuge rotor in which each bucket is supported by an independent bucket hanger member disposed within a cavity in the rotor. Each hanger member is spring biased in a radial direction toward the axis of rotation, and is supported by a guide sleeve with fastening means extending through the guide sleeve. The guide sleeve prevents rotation of the bucket and hanger member with respect to the rotor body.