Abstract: An improved centrifuge. The centrifuge may be a conventional centrifuge having a rotor and a plurality of tube receiving adaptors inserted into the rotor in a circular configuration. The improvement comprises a flexible flap having a fixed end mounted on the rotor at an adaptor and having an opposing free end. The free end extends radially inward toward the center of the rotor when the rotor is not rotating and is folded by centrifugal force back to cover the opening in the adaptor when the rotor is rotating. By covering the opening in the adaptor, the flexible flap eliminates the high pitch whistle otherwise generated by the adaptor when rotating without a tube inserted.

Abstract: A centrifuge rotor and sample containers for reorienting gradients and separating the components of a sample. The rotor contains a plurality of cylindrical recesses equally spaced about its rotational axis. The recesses are open at the top and have a concave hemispherical bottom. A cylindrical plug member is positioned in each of the recesses, and the lowermost end of the cylindrical plug member is formed in the shape of a concave hemisphere. A sample container in the shape of a hollow sphere is positioned between the hemisphere of the cylindrical plug member and the hemisphere of the recess bottom, and means are provided to retain the cylindrical plug member in the recess. The symmetry of the hemispherically shaped sample container is advantageous for minimizing any disturbance to a gradient during reorientation. In another embodiment, a centrifuge rotor is provided which is adapted for fixed angle centrifugation with hemispherical sample containers.

Abstract: A transparent tube for use in the cavity of the rotor of a high speed centrifuge. The tube is penetrable at its bottom end by a needle of a hypodermic syringe. The tube is open at the top and has a rounded bottom with an opening forming a passageway therein. A recess forming a shoulder co-axial with the passageway is provided both on the inner side and the outer side of the tube. A resilient plug having flanges at each end provides a tight fitting closure for the passageway and recesses.

Abstract: 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.

Abstract: A centrifuge rotor assembly having a resilient liner with at least two separate chambers. Fluid communication between the separate chambers is automatically controlled in response to centrifugation operation of the rotor. When the rotor is stationary, the liner assumes a first position within the rotor where an annular chamber is sealed from a central chamber. When a fluid sample is placed within the liner of the rotor and the rotor is subjected to centrifugation, the centrifugally induced forces of the fluid mixture shift the liner to a second position, opening the sealed condition between the central and annular chambers to permit fluid communication between the respective chambers. When the centrifugation operation has been completed and the rotor returns to its stationary position, the inherent resilient structural characteristics of the liner automatically re-establish the seal between the respective chambers.

Abstract: A multi-compartment centrifuge rotor having a sealing element which automatically controls in response to the centrifugation operation the fluid communication between the separate chambers within the rotor. The sealing element is situated within the rotor above an annular and an inner chamber used for containing a fluid mixture. When the rotor is assembled and stationary, the sealing element establishes a seal between the respective chambers. During the rotation of the rotor, centrifugal forces exerted directly on the sealing member cause it to move and release the seal between the respective chambers to allow fluid communication between the chambers. As the rotor returns to a stationary position and the centrifugal forces induced on the sealing member subside, the sealing element automatically re-establishes the seal between the respective chambers.

Abstract: An air driven centrifuge which utilizes a stator with a floating stator pad for alleviating excessive vibration of the rotor associated with critical rotating speeds. The floating stator pad incorporates means for increasing the friction between the pad and the stator in order to increase the ability of the stator pad to provide greater dampening of the rotor for improving the smoothness and stability of its operation.

Abstract: A centrifuge test tube cap assembly for a thin flexible test tube including a stem member having a stud adapted to extend out the mouth of the test tube and having a cylindrically shaped skirt dimensioned to fit snugly within the inner surface of the mouth of the test tube, the stem member also having a slanting annular surface between the skirt and the stud, slanting outwardly in the downward direction, and the assembly also including a crown member having a depending outer lip, the outer diameter of which is substantially the same as the outer diameter of the thin flexible tube and having an annular inner surface slanting outwardly in the downward direction, the slanting surface of the lip conforming to the shape and slant of the slanting annular surface of the stem member so that when the crown is positioned over the stem and tightened axially on the stem member the upper edge of the flexible tube is deformed inwardly to squeeze the upper edge of the tube between the respective slanting surfaces of the ste