Abstract: In a centrifuge including a centrifuge rotor and a drive shaft for spinning the rotor at selected rotational speeds, a safety device adapted to prevent the rotor from attaining a rotational speed likely to cause the rotor to explode with a force that could not be contained within the centrifuge housing. The device includes a hub member having a central opening adapted to receive the upper end of the drive shaft for supporting the rotor thereon, the hub member being formed with oppositely disposed heavier portions connected by relatively thinner web sections. The web sections are so designed and constructed, relative to the weight of the heavier sections, as to rupture at a predetermined rotational velocity of the rotor thereby causing the hub member to depart from the shaft, leaving no driving capacity or support for the rotor on the shaft, which then causes the rotor to separate from the drive shaft before attaining a hazardous rotational speed.

Abstract: A nematic liquid crystal composition suitable for use in displays and in other liquid crystal applications comprising a mixture of negative dielectric anisotropy low temperature characteristic nematic non-Schiff base liquid crystals and strongly positive dielectric anisotropy nematic non-Schiff base liquid crystals doped with traces of cholesteric liquid crystal are disclosed. These compositions have low actuation voltages and very rapid response times.

Abstract: An active filter for electronic circuits comprising a single frequency bandpass filter including two stages each comprising a differential input high performance operational amplifier with the output of a second stage being connected in feedback relationship to one input of the first stage and the output of the first stage being interconnected with one input of the second stage. The output of the filter circuit is taken from the output of the first stage of the amplifier and the input to the filter circuit is the negative input of the first stage of the amplifier.

Abstract: A tool is provided for the angular alignment of cells and counterweights in centrifuge rotors having diametrically opposite cylindrical chambers for the reception of such cells and counterweights, the rotor and chambers having parallel axes, each cell having a window holder with a straight sided aperture and each counterweight having a center hole and an alignment hole spaced radially therefrom. The tool comprises an arm which extends along a diameter of the rotor when the tool is in position for use. At a first end of the diametrically extending arm there is a tool arm perpendicular to the diametrically extending arm and extending in each direction from the diametrically extending arm. At the second end of the diametrically extending arm there are a cell guide and a counterweight guide, each extending from the diametrically extending arm at right angles thereto.

Abstract: In a centrifuge including a centrifuge rotor and a drive shaft for spinning the rotor at selected rotational speeds, a safety device adapted to prevent the rotor from attaining a rotational speed likely to cause the rotor to explode with a force that could not be contained within the centrifuge housing. The device includes a safety link handle assembly supported on the top of the rotor on the rotation axis thereof having an arm designed to rupture and depart from the handle assembly at a predetermined speed thereby creating an imbalance condition of such a magnitude that the rotor separates from the drive shaft and is thereby prevented from attaining a hazardous rotational speed.

Abstract: An air driven centrifuge including a rotor chamber having a rotor seat mounted in the bottom thereof and including a rotor having a plurality of turbine flutes formed in an under side thereof. The rotor seat includes driving air jet means for impinging pressurized air streams against the turbine flutes of the rotor for supporting and spinning the rotor on an air cushion above the rotor seat. Support air jet means are also provided in the seat for directing pressurized air streams against the under side of the rotor for supporting the rotor when the driving air jet streams are inactivated. A brake and stabilizing means is included for decelerating the spinning rotor and includes a friction bearing means on the bottom portion of the rotor and a stabilizer means movable into engagement with the bearing means and cooperating with the bearing means to produce a frictional load against the bearing means thereby causing the rotor to decelerate and also stabilizing the rotor as it slows to a stop.

Abstract: 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.

Abstract: A vacuum bushing for an ultracentrifuge that minimizes excessive oil loss due to the high pressure differential across the bushing and allows automatic reclaiming and reusing of a major portion of the uncontaminated oil flow. The bushing is provided with first and second annular chambers, one chamber being connected to an atmospheric oil reservoir and the other chamber being connected to a vacuum oil reservoir. The major oil flow is from the atmospheric reservoir to the first chamber, along the rotor drive shaft to the second chamber, and then to the vacuum reservoir. The vacuum reservoir is connected to the atmospheric reservoir by a one-way check valve so that the oil is automatically returned to the atmospheric reservoir when the centrifuge is deactivated and the vacuum released.

Abstract: 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.

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