Abstract:
A tridentate conjugate has three chemical moieties, or tridentate members, attached through an appropriate spacer moiety. At least two of the tridentate members are relatively small molecules, usually less than about 7,000 Daltons in size. The particular appropriate spacer moiety selected for a tridentate imparts certain steric properties to the tridentate conjugate. In one embodiment, the binding of a macromolecular specific binding partner to one of the tridentate members sterically inhibits the binding of a different macromolecule to another tridentate member. In another embodiment, the binding of a first tridentate member to a macromolecule restricts the subsequent binding of a second tridentate member to a proximate location on the same macromolecule.
Abstract:
A sample counting support for scintillation counting of a radioactive labeled sample comprises a base material covered with a thin layer of dry solid scintillator in a substantially permanent form so that the support may receive the sample and produce light emissions in response to particles emitted by a radioactive substance labelling said sample.
Abstract:
An electrophoretic gel cooled cell including a gel supporting surface. The cell includes members for holding gels against the supporting surface such that gels of either of two dimensions may be used with the cell. A reservoir adapted to hold a cooling medium shares a common wall with the supporting surface to cool the gel retained by the members. The reservoir has a large opening which may be closed by a cover for easy insertion and removal of the cooling medium from the reservoir. A venting valve in the reservoir cover vents gas in the reservoir to atmosphere and closes when the cover is in an inverted position to prevent condensate leakage through the vent.
Abstract:
A device for generating a plurality of gas bubbles in a liquid. The device includes a conduit (58) adapted to carry the liquid. A first gas chamber (96) is formed near the conduit and an orifice (53) proximate a side wall of the conduit defines a passageway (60) between the first gas chamber and the conduit. A valve member (50) is adapted to seat against and close the orifice. The device may include a second gas chamber (86) and a diaphragm (36) responsive to gas pressure in the second gas chamber. A conduit (98) connecting the first and second chambers may include a variable vent (104) for controlling the size and number of gas bubbles injected into the liquid flowing in the conduit.
Abstract:
An apparatus and method of protecting a centrifuge from rotor overspeed and resultant mishap by computation of the rotor moment of inertia is disclosed. In the preferred embodiment, a centrifuge is driven by a rotor (10) mounted on a shaft (14) which shaft is in turn driven by a constant current motor (16). A tachometer (20) for detecting angular velocity of the drive shaft is used. A desired and ultimate centrifuge operating speed is selected by the operator. The times at which the rotor passes through discrete speeds are recorded and from the time difference the moment of inertia is computed. The moment of inertia can thereafter be utilized to discretely identify or ''finger print'' rotors to disqualify certain rotors from use in particular centrifuge protocols and establish gross limits of centrifuge operating speed.
Abstract:
A method for obtaining an actual linear standard curve in a sandwich type of immunoassay where a first antibody bound to an insoluble support and a second unbound labelled antibody complex with the antigen contained in a test sample to form an insoluble antibody:antigen:labelled antibody complex which is then detected. Unbound unlabelled first antibody and/or unbound unlabelled second antibody are added to the reaction mixture to divert excess antigen away from the desired end-product complex, thus rendering the antigen of interest the rate-limiting factor in the overall immunoreaction. This results in a pseudo first-order reaction which produces an actual linear standard curve.
Abstract:
The peak verify time for kinetic nephelometric measurements of reactions between antigens and antibodies is adjusted as a function of the magnitude of the peak rate in order to reduce the time required for peak verification. The scatter signal is zeroed following the end of the peak verification period and the reaction is tested for antigen excess. Reactions during the antigen excess check having rates that exceed a threshold value are accepted as being valid, and no additional measurements are made for such samples. Reactions during the antigen excess check having rates that are less than the threshold value are rejected as being in antigen excess. Samples found to be in antigen excess are diluted and then reanalyzed.
Abstract:
A tube-cutting apparatus and method for separating centrifuged materials in which a resilient axial compressive force is exerted on tube (50) during cutting by spaced tube-holding members (52) and (102); and the cutting knife (18) has flat upper (84) and lower (82) sides against which the severed portions of the tube (50) are held in sealing engagement by the axial force. Independent adjustment is provided for (a) the relative positions of the tube (50) and the cutting knife (18), and (b) the relative positions of the spaced tube-holding members (52) and (102).
Abstract:
A centrifuge rotor (10) is provided with a plurality of cavities (20) having a non-circular cross-section for receiving mating multi-angle adapters (24), which may be inserted in the cavities (20) with selected rotational alignment about the cavity axes (m-m'), to determine a plurality of select angle receiving chambers (26) in the rotor (10) for sample containers.
Abstract:
Apparatus for the optical quench of a sample (10) including a photodetector (12, 14), means for positioning the sample in an operative relationship with the photodetector, and a liquid crystal light valve (15) disposed between the sample and the photodetector when the sample is in the operative relationship. The light transmission characteristics of the liquid crystal light valve are varied in response to an attenuation signal generated by a power supply. The apparatus may further include means responsive to the photodetector means for generating a control signal and the power supply means may further be responsive to the control signal for varying the attenuation signal with respect thereto.