Abstract: A one piece integrally formed sectional shaped liner for use in combination with similarly shaped sectional liners in a generally cylindrical chamber of a centrifuge rotor. The utilization of a plurality of similarly shaped plastic liners within a single rotor chamber allows for the placement of different fluid samples in a single rotor during one centrifuge run. The liners are designed in such a manner that they do not require a separate capping means and are preferably made through a blow molding process. The liners are designed to provide adjacent support to each other during the centrifugation run.

Abstract: An integrating analog-to-digital converter for producing a digital output signal representing the value of an analog input signal which may have either a positive or negative polarity. The converter uses a switching circuit to reverse an integrator capacitor between charge and discharge periods so that the same input-signal-controlled current source can be used to both charge and discharge the capacitor. This results in inherent zero calibration because any offset errors during the charge cycle are cancelled out by equal and opposite offsets during the discharge cycle.

Abstract: A direct drive system for a high speed ultracentrifuge. The drive spindle assembly is removable through the rotor chamber without disturbing any vacuum seals that are present to isolate the requisite vacuum environment in the rotor chamber for high speed rotation. All of the high speed bearings are connected to the spindle assembly for removal as a unit. An induction motor provides the direct drive with the motor armature mounted on the drive spindle assembly.

Abstract: A device for the sequential fractionation of the contents of a centrifuge tube containing centrifugally separated contents utilizing a syringe-like apparatus. The present invention utilizes removable syringe tips that are mounted on a chamber housing for extraction and retention of a precise volume of centrifuged fluid from the centrifuge tube. The syringe-like apparatus is mounted to a frame in such a manner that the chamber housing is movable relative to the plunger or piston to permit precise movement of the chamber housing with the removable syringe tip into the centrifuge tube for delicate and precise removal of the desired fraction of the fluid. The syringe tips are removed with each fraction that is collected from the contents in the centrifuge tube and can be placed in a storage rack for subsequent analysis.

Abstract: A method and apparatus for layering a liquid sample onto a support liquid through a narrow filler passage in a neck protruding from the opening in a substantially closed, flexible centrifuge tube by supporting the tube with its liquid support contents in an upright position, attaching a funnel shaped container to the neck of the tube, applying a squeezing force to the flexible tube to reduce its internal volume thereby forcing the liquid contents into the neck thereof to form a meniscus adjacent the opening of the filler passage, adding a sample liquid into the funnel shaped container above the filler opening and in contact with the meniscus of the support liquid, and releasing the squeezing force from the tube allowing it to return to its normal volume thereby drawing the sample into the tube layered on top of the support liquid.

Abstract: A process for making an integral one piece rotor liner for use with a high speed rotor. The liner has an inner chamber and an annular chamber designed to operate in conjunction with the rotor operation to automatically allow fluid communication between the respective chambers during centrifugation and automatically establish a seal between the respective chambers subsequent to the centrifugation operation. The process for making the one piece rotor liner generally comprises a first step of molding the liner in an intermediate elongated configuration wherein the inner chamber portion is integrally joined to and spaced from the annular chamber portion of the liner by a reversing section. The general configuration of the inner chamber is located at one end of the elongated liner shape and the general configuration of the annular chamber is located at the other end of the elongated liner.

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 identification means placed adjacent the test tube cavities in a centrifuge rotor. The identification means utilizes recessed or indented indicia which are positioned on a circular ring raised above the generally flat top surface of the rotor. The identification indicia are used for identifying or labeling each of the test tube cavities in the rotor. The raised nature of the ring eliminates the possible establishment of weak points or areas in the top surface of the rotor during centrifugation.

Abstract: A dual seal arrangement for use in a rotor to ensure the retention of the fluid sample within the test tube cavity during high speed centrifugation in an ultracentrifuge. The dual seal arrangement provides not only a seal on the test tube within the rotor tube cavity, but also a seal on the rotor tube cavity itself. One seal provides a capping arrangement on the test tube to securely seal the fluid sample within the test tube which rests within the rotor tube cavity. A secondary seal is positioned within the rotor tube cavity above the capping seal to provide a complete seal of the rotor tube cavity above the test tube.

Abstract: A valve construction in the form of a "flex-finger" or flexible stem valve is provided for handling substances which are highly corrosive or very active chemically. The valve body, valve seats, a valve ball and flexible finger or flexible valve stem are all composed of chemically resistant material. The flexible stem has an outer end secured in the valve body against rotation with a fluid tight joint and an inner end for actuating the "ball". The flexible stem is composed of material which is sufficiently resilient so that it may be caused to travel in a circular or orbital path carrying or actuating a "ball" or other attachment into and out of engagement with the valve seat or seats.

Abstract: Nematic liquid crystal compositions for use in displays and in other liquid crystal applications comprising a mixture of a nematic biphenyl liquid crystal material, nematic liquid crystal material other than nematic biphenyl which is incompatible with the nematic biphenyl (e.g. when mixed together, it will form a smectic phase instead of a nematic phase) which is present in a concentration that will render the total mixture with improved electro-optic properties and nematic liquid crystal material other than a nematic biphenyl which is compatible with the nematic biphenyl and present in a concentration sufficient so that the mixture forms a satisfactory nematic phase for use in a field-effect display device. The preferred biphenyl-incompatible constituents are certain ester-type nematic liquid crystals and the biphenyl-compatible constituent are other certain ester-type nematic liquid crystal.

Abstract: A centrifuge test tube cap assembly for sealing a thin walled test tube used primarily with a vertical tube rotor. The cap assembly is designed for convenient and easy removal from the test tube through the use of internal means which activates the direct sealing and unsealing of the cap with respect to the test tube. The mechanism of the tube cap provides for convenient removal of the cap assembly from the test tube which is necessary in order to insert or remove the liquid to be subjected to centrifugation.

Abstract: An improved apparatus and method for braking the rotation of a centrifuge rotor is disclosed comprising magnet means operable in a first condition wherein substantially no eddy currents are induced in a rotating rotor made of electrically conductive material by the magnetic flux of the magnet means and a second condition wherein eddy currents are induced into the rotating rotor sufficiently to slow the rotor. In one embodiment, magnet means is movable from a first position wherein substantially no eddy currents are induced in an electrically conductive portion of the rotating rotor by the magnetic flux to a second position wherein eddy currents are induced into the rotating rotor in a quantity sufficient to slow the rotor.

Abstract: A test tube cap assembly for centrifuge rotor tubes. A stem member slidably moves within a crown member to exert a direct force on a bushing to securely grip the upper portion of a test tube located within the crown member. The stem member and the bushing have generally mating frustoconical surfaces to provide a wedging action on the upper portion of the test tube. The wedging action serves to not only seal the tube, but also support the upper end of the test tube by restraining the centipetal side of the tube from pulling away from the cap. The operation of the cap assembly is enhanced by the hydraulic forces exerted from within the test tube by the contained liquid.

Abstract: A control element for sensing the motion of a movable member within a machine to automatically prevent opening of a cover or guard on the machine when the member is moving. The control element has one of its ends brought into contact with a portion of the movable member and its other end connected to a latching mechanism located adjacent the machine cover. Being an elongated flexible member, the control element moves in response to the movement of the movable member. When the member is stationary, the end of the control element in contact with the movable member causes the control element to become an elongated rigid member to permit the latching mechanism to turn and allow the opening of the cover over the movable member.

Abstract: A variable resistor with a dual ratio input shaft that permits rapid and precise adjustment of the voltage or current level in an electric circuit. A single shaft operates the respective drive elements in the mechanism to provide variable control from a single control knob. The shaft is longitudinally slidable between two drive positions. One drive position allows more rapid adjustment of the resistance value for each turn of the control knob than the other drive position which permits more precise adjustment of the resistance value for each comparable turn of the control knob.

Abstract: Disclosed herein are powder compositions useful for making conductors, e.g., microcircuit conductors, end terminations for capacitors, electrodes for gas discharge display devices, etc. The compositions comprise inorganic powders dispersed in an inert vehicle and are printed and fired in the conventional manner on dielectric substrates. The inorganic powders comprise a mixture of nickel and/or aluminum or copper and boron. Glass powder and/or silicon powder may also be present.

Abstract: An improved cathode assembly for a gas discharge display panel is disclosed providing a first series of cathode elements in a first direction and a second series of cathode elements in a second direction. A separate "keep-alive" element and "initiate signal" element are also provided. The keep-alive element maintains a localized source of ionized gas at all times. Upon activation of the initiate signal element, the ionized gas moves from the keep-alive element to the initiate signal element. The first direction elements are then sequentially activated to cause the ionized gas to pass from the initiate signal element sequentially to each of the first direction elements until the selected first direction element has been reached. The second direction elements are then sequentially activated to cause the ionized gas to pass from the selected first direction cathode element to the second direction cathode elements in sequence until the selected second direction element has been reached.

Abstract: A stopping member located within an air driven rotor and designed to respond to a magnetic field generated within the rotor housing, causing the completer stoppage of the rotor subsequent to its high speed centrifugation. The stopping member is comprised of a ferrous metal element positioned within the rotor for alignment with the poles of a magnet to facilitate sufficient attractive forces between the magnet and the metal element to completely stop the rotative motion of the rotor on a support cushion of air.

Abstract: An air levitation jet located in the center of a rotor seat to provide a supporting and holding air flow between a rotor and the rotor seat. Integrally formed within both the rotor and the rotor seat are conical and frustoconical portions which respectively establish a conical flow path and an adjoining frustoconical flow path to aid not only in the centering of the rotor within the rotor seat, but also in the retaining of the rotor in alignment with its rotational axis. Air under pressure exiting the levitation air jet in the center of the rotor seat proceeds along the conical flow path and into the frustoconical flow path with sufficient velocity to establish a reduced pressure in the flow path between the rotor and rotor seat that is less than atmospheric pressure, causing the rotor to remain securely positioned on a cushion of air within the rotor seat.