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 film badge sensitive to non-ionizing radiation and a method of making same. The film badge consists of dissolved bilirubin bound in a polymeric film base and sealed within an optically transparent substrate. The film badge is useful during phototherapy for the treatment of hyperbilirubinemia in the newborn and is capable of measuring the total irradiance effective in decomposing bilirubin.

Abstract: A valve system is provided for completely draining a vessel which may contain corrosive liquids and for preventing leakage until the vessel is to be drained. This is accomplished by providing the vessel with a throat at the bottom, an outlet tube connected to the throat and a pressure tube connected to the outlet tube with a source of fluid or gas pressure connected to the outlet tube between the throat and the pressure tube to force gas upward against (and/or through) the throat, thereby preventing the flow of liquid downwad through the throat. Agitation of the vessel contents can be achieved by flow of gas through he throat.

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: A bioelectrical impedance measuring system that measures and indicates the impedance of a biological subject, such as one or more human extremities. The system measures and indicates a basal impedance value of the measured subject, and also indicates short temporal variations in the basal value. In the system an excitation signal, derived from an electrical signal source, is coupled to the subject by excitation electrodes and a resulting subject output signal is sensed by receiver electrodes. The subject output signal is electronically subtracted from a reference signal derived from the signal source, and the resulting signal is used to drive a display unit. The system includes a null detector connected to the display unit input, and an automatic gain control unit responsive thereto, connected in the subject output signal path to automatically maintain the system in a nulled condition.

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: A differential pressure transmitter of the sensing diaphragm type is disclosed having low side overrange protection in which the central hub of the sensing diaphragm is releasably biased against the free end of the resilient spring in the transmitter body. A valving mechanism is provided so that under conditions of low side overrange, after the sensing diaphragm has separated from the spring, the valving mechanism provides a chamber of nonresilient body walls behind the sensing diaphragm filled with trapped fill fluid so that the sensing diaphragm is not distorted beyond its elastic limit by the high negative differential pressure.

Abstract: Detection of exhaustion of sodium form water softeners is accomplished by subjecting sample of the outflow from a water softener to reverse osmosis in order to separate monovalent (sodium) and divalent (hardness or magnesium and calcium) ions differentially from the outflow and measuring conductivity before and after the reverse osmosis. The two conductivities are compared in a ratiometer or differential device. After the softener becomes exhausted the divalent ion concentration in the outflow increases. Consequently the conductivity ratio changes to indicate that the water softener has become exhausted.

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: Improved apparatus for automatically calibrating and verifying the calibration of a chemical analyzer of the type which determines the concentration of a component in chemical or biological samples, e.g. concentration of glucose in blood or urine, wherein a sample changer sequentially advances samples into position for analysis. Calibration of the analyzer is performed by measuring a calibration standard of known concentration and generating a conversion factor therefor which converts the measured value of the standard to the known value thereof. Means is provided for storing conversion factors and proper calibration of the analyzer is verified by comparing successive conversion factors. If the compared conversion factors differ by more than a predetermined amount, the sample changer is halted and the calibration standard is remeasured.

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 semiconductor material is doped or alloyed under vacuum with an impurity by thermal decomposition and by sedimentation resulting from centrifugal force. The doping material is alternatively applied by evaporation before being subjected to centrifugal force and may be heated up to the melting point before completion of the centrifugal action. A centrifuge is provided having a thermal insulating layer between the outer wall of a rotor and a support for basic semiconductor material to be doped. The doping impurity material to be evaporated onto the basic solid state material is placed in the center of the centrifuge rotor.

Abstract: Improved liquid crystal compositions comprise a major portion by weight of at least three different p-alkoxybenzylidene-p'-aminophenylalkanoates and a minor portion by weight of p-methoxybenzylidene-p'-butylaniline and p-ethoxybenzylidene-p'-butylaniline. The compositions have broader nematic ranges than either ternary mixtures of the alkanoates or binary mixtures of the other two compounds. In addition, when certain dopants are added to the compositions, optimum improvement in properties is obtained using less dopant than that required by prior art compositions.

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 densitometer for providing an output which is a function of the density of a film badge in a photodosimeter system. The light passing through the film badge is received by a photodiode which generates a current signal which is directly proportional to the intensity of the received light. The current signal is converted to a voltage signal, the converting means being biased so that the voltage signal is zero when no light is received by the photodiode. The voltage signal is applied, together with a reference voltage, to a log-ratio circuit which generates an output signal proportional to the log of the ratio of the reference voltage to the voltage signal, the output of the log-ratio circuit being displayed. A circuit is operative, when the film badge is removed from the light path, to adjust the reference voltage until the output of the log-ratio circuit is zero.

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 spectrophotometer system having a first stepper motor driving a wavelength scanning mechanism and a second stepper motor driving a chart recorder, both motors being operative in response to pulses from a system clock. The clock frequency is successively divided by first and second cascaded, switch-selectable sets of frequency dividers. The output of the first divider is applied to the wavelength motor and determines wavelength scan speed. The output of the second divider is applied to the chart motor and determines chart scale expansion. A decoder monitors the frequency selections of the first and second sets of frequency dividers, and upon detection of a frequency selection outside the capability of the chart motor, the decoder provides an output which inhibits both motors. The decoder output additionally actuates a visual indicator to inform an operator of the invalid selection.

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: An electronic process controller is disclosed having automatically bumpless operation. Changes such as transfer between manual and automatic modes, switching between set point sources and adjustment of control parameter values are all accomplished bumplessly with the aid of a settle circuit which adjusts the automatic control signal for bumpless switching while the manual memory freezes the process control signal at its last value before the change was initiated.