Abstract: A re-entrant radio-frequency (RF) TE11-mode cavity resonator allows generating a spatially homogeneous RF magnetic field for magnetic resonance (NMR, MRI) applications. The azimuthal current distribution is truly (continuously) sinusoidal. Moreover, the geometry allows tuning the cavity resonance frequency over a wide range. The resonator includes an outer cylindrical shell, and an inner re-entrant shell extending only along the ends of the outer shell. The magnetic resonance target of interest is placed in the middle region of the outer cylindrical shell. Multiple re-entrant inner shells can be used, particularly if multiple resonances are desirable. The resonator can be driven capacitively or inductively, for example by placing excitation loops in the space between the outer and inner shell. Multiple excitation loops are used to drive the resonator in quadrature. The resonance frequency of the cavity can be tuned by rotating tuning paddles placed between the inner and outer shells.

Abstract: An apparatus for tuning and/or matching a RF coil in a NMR probe comprising a first variable capacitor electrically connected to the coil and a first motor capable of coupling to the first variable capacitor. The first motor when coupled to the first capacitor adjusts a capacitance associated with the first capacitor. The first motor is capable of operating in a strong magnetic field and is capable of not disturbing homogeneity of said magnetic field when said motor is not operating. The apparatus may further include a second variable capacitor and a second motor. The first motor is further capable of coupling to the second capacitor for adjusting a capacitance associated with the second capacitor. The second motor moves the first motor between coupling with the first capacitor and coupling with the second capacitor. The mechanism may be employed to manipulate variable inductive loads for tuning and/or matching.

Abstract: A gas chromatographic device has an inlet system, a column and a pressure reducing means combined and assembled in such a series arrangement that provides adequate system performance with shorter wide bore column length and shorter sample analysis times needed during a peak integration and evaluation process performed by a connected mass spectrometer system. Pressure reducing means may be integral part of the inlet system or the column when positioned between the inlet system and the column. Pressure reducing means preferably positioned before the column and being capable of reducing the pressure prevailing at the inlet of said pressure reducing means to a column outlet pressure which is essentially vacuum. Preferably, the inlet pressure of the device is in a range between 10 kPa and 1000 kPa and the absolute pressure prevailing at the outlet of said pressure reducing means is in a range between 0.00001 kPa and 50 kPa.

Abstract: A birdcage coil comprises a number of elements in birdcage geometry wherein the density of elements is such that the contribution to the total inductance from the mutual inductance of said legs exceeds 45% by conventional model calculation. To accommodate the desired density of elements, necessary capacitances are obtained from compact structures such as inter-digitated patterns which may be oriented axially or between elements, or from arrangements of element portions on opposite sides of a cylindrical substrate.

Abstract: A sputter ion pump incorporating a corrugated style anode comprising a plurality of cylindrical adjacent hollow cells provided with cross sections having substantially the same area and an arcuated perimeter.

Abstract: The present invention provides monolithic polymer matrices for the separation of bio-organic molecules by liquid chromatography. In one embodiment, the matrix is formed from a polymerization mixture including (i) a hydrophobic monomer, (ii) a crosslinking agent, and (iii) a porogenic solvent or mixture of porogenic components. The monolithic matrices of the invention are particularly useful for resolving polynucleotides (e.g., DNA and/or RNA) in samples by way of reversed-phase ion-pairing chromatography.

Abstract: Spectroscopic apparatus for sequentially detecting the presence of a plurality of elements in a sample. The apparatus includes a plurality of lamps (1a-1e) each of which is for detecting the presence of a respective at least one predetermined element in a plurality of elements. A beam selector (13) which may be a mirror, is operative to direct a beam of light (7) from any one of lamps (1a-1e) to an analysis zone (8). The apparatus includes a monochromator (15), the drive (24) of which is under the control of a controller (25) with a memory device (26) linked thereto. Predetermined settings for the monochromator corresponding to the peak settings for each wavelength of interest can be stored in memory (26) for subsequently driving the monochromator to those settings without the need to undertake a peaking routine for each elemental analysis, thereby saving analyses time.

Abstract: A vacuum pump, such as a turbomolecular pump, a molecular drag pump or a hybrid pump, is adapted for use with a backing pump. The vacuum pump includes a housing having an inlet port and an exhaust port for coupling to the backing pump, one or more vacuum pumping stages disposed in the housing, each of the vacuum pumping stages having a stationary member and a rotating member, and a gas turbine. The gas turbine includes a gas inlet, a gas outlet coupled to the exhaust port, and a rotor coupled to the rotating members of the vacuum pumping stages. A gas flow, produced by the backing pump, through the gas turbine causes the rotor and the rotating members of the vacuum pumping stages to rotate, wherein gas is pumped by the vacuum pumping stages from the inlet port to the exhaust port.

Abstract: Radio-frequency (RF) heating is used to accelerate the thermal equilibration of dielectrically lossy nuclear magnetic resonance (NMR) samples. High-power heating RF pulses are applied to the sample before lower-power measurement RF pulses, using any of the NMR probe coils. The heating pulses are offset in frequency relative to the measurement pulses, such that the heating pulses do not magnetically affect the spins of interest. Heating pulse sequences of decreasing power can be used to prevent the sample temperature from overshooting the desired equilibrium temperature. Heating RF pulses can pre-establish the thermal effects of both measurement-independent and measurement-dependent heating. For pre-establishing the thermal effects of measurement-dependent heating, the heating pulse transients are chosen to be proportional to subsequent measurement pulse transients.

Abstract: A radiotherapy machine beam treats a region of a subject while the region and volumes abutting the region are imaged by a magnetic resonance imaging system. The beam and an excitation coil assembly of the imaging system are arranged so the beam is not incident on the coil assembly and magnetic fields derived from the coil assembly do not interact with the beam. The excitation coil assembly includes two spaced winding segments for producing a main DC magnetic field; the segments are located on opposite sides of the region. In one embodiment, wherein the excitation coil assembly is mounted independently of movement of an axis of the beam, the winding segments have a common axis generally aligned with an axis about which the beam axis turns. A treatment couch for the subject fits within aligned central openings of the winding segments. The coil produces main magnetic field lines that extend generally in the same direction as the axis about which the beam turns.

Abstract: A high-vacuum pump includes a first vacuum pump section and a second vacuum pump section coupled in series and having an interstage region between them. The vacuum pump further includes a housing containing the first and second vacuum pump sections. The housing includes a high conductance peripheral duct surrounding all or part of the interstage region and coupled to the interstage region. The housing defines a first inlet port coupled to an inlet of the first vacuum pump section, a second inlet port coupled to the peripheral duct, and an exhaust port coupled to an outlet of the second vacuum pump section. Examples of high-vacuum pumps according to the invention include turbomolecular vacuum pumps, diffusion pumps and mixed vacuum pumps which include both axial flow stages and molecular drag stages.

Abstract: A vacuum pump includes a housing having an inlet port and an exhaust port, a motor disposed in the housing, and one or more vacuum pumping stages disposed in the housing and operationally coupled to the motor for pumping gas from the inlet port to the exhaust port. The motor includes a stator disposed on a central axis and a rotor disposed around the stator. The rotor rotates about the central axis when the motor is energized. The motor may be located at the center of the housing, and the vacuum pumping stages may be disposed around the motor in an annular configuration. The inverted motor configuration facilitates a compact vacuum pump structure.

Abstract: A vacuum pump (11) comprises a body (1), a rotor member (9) having a plurality of rotor disks (12) coupled to corresponding plurality of stator rings integral to the body (1). The rotor, member has an axial bell-shaped cavity (13). A rotating shaft (15) and an electric motor (7, 8) are disposed within the axial bell-shaped cavity (13). The rotating shaft (15) is supported by rotation supporting means (5a, 5b). The electric motor comprises a stator (7) integral to the body (1) of the vacuum pump (11) and a rotor (8) coupled to the internal surface of the axial bell-shaped cavity (13) of the rotor member (9).

Abstract: A butterfly valve includes a valve housing having a fluid conduit, a seal plate assembly including a seal plate, and a closure assembly. The closure assembly includes a main shaft mounted in the valve housing and rotatable about a longitudinal axis between an open position and an intermediate position, a crank shaft rotatable about the longitudinal axis between the open position and a closed position, a hub affixed to the main shaft and movably coupled to the seal plate assembly to permit translation of the seal plate assembly with respect to the hub, a roller engaging the seal plate assembly and mounted to the crank shaft for eccentric rotation about the longitudinal axis, and one or more springs coupled between the seal plate assembly and the hub for biasing the seal plate toward the intermediate position. The valve may include a valve actuator which rotates the crank shaft about the longitudinal axis between the open position and the closed position.

Abstract: Air cooled x-ray generating apparatus is provided with a unitary vacuum enclosure having a rotating anode target and a cathode assembly for generating x-rays. The cathode assembly may be placed within the vacuum enclosure through an opening in the top wall thereof, and comprises a disk which completely covers this opening. The unitary vacuum enclosure and the disk form a radiation shield. A plurality of fins are disposed on the exterior side wall of the vacuum enclosure, and a shroud is attached to the fins to provide additional protection of ambient against radiation. The cathode assembly may be placed through a side wall of the vacuum enclosure. The additional protection against excessive radiation in this design is provided by a shielding member placed in proximity to the anode target. The shielding member extends from the side wall of the enclosure and is substantially parallel to the top wall.

Abstract: In a mixed WDM/SONET network having optical and SONET layers, the communication between these layers is provided by optoelectronic units. The optical layer of the mixed network is presented by a WDM equipment and a service restoration system which utilizes optical switches and protects the mixed network from loss of the WDM traffic. The optoelectronic units monitor WDM and SONET traffic and control optical switches by utilizing a WDM/SONET adapter for communicating information between WDM and SONET equipment. The WDM/SONET adapter generates temporary SONET signals and passes these signals through the WDM and SONET equipment, and a service channel for transmitting control signals from the WDM/SONET adapter to the optical switches.

Abstract: A method and system of Coherence Division Multiplexing (CDM) for transmitting of a plurality of optical signals over the same optical fiber utilizing path-matched interferometry and phase modulation of partially coherent light, based on optical selecting and filtering of each CDM optical signal and reducing noise affiliated with other non-selected CDM optical signals.

Abstract: An x-ray target assembly is formed by passing a rotary shaft through the center hole of a graphite disk such that the back surface of the disk rests on a flange part of the rotary shaft and the front surface is contacted by a nut which engages with the tip of the rotary shaft. Annular brazing materials are placed adjacent contact areas where the disk contacts the rotary shaft and the nut such that braze joints are made to secure the disk with the nut and the rotary shaft. Grooves may be formed on the surfaces of the nut and the flange part of the rotary shaft which contact the disk such that the brazing material can more efficiently fill the gaps between contacting surfaces.

Abstract: An x-ray target has a substrate of a carbonaceous material such as graphite which is secured to a rotary shaft so as to rotate therewith. A portion of outer peripheral surface of the substrate is covered by a target plate, while the other portion is covered with a thin iridium layer with thickness in a range between 50 .ANG. and 250 .ANG. so that the trapped gas species like H.sub.2, CO, CO.sub.2 can escape therethrough, and to retard the diffusion of ambient gas species into the substrate while the infrared emissivity of the underlying substrate is not lowered appreciably thereby.

Abstract: A vacuum pump a the magnetic bearing assembly includes the magnetic bearing assembly with rotor position sensors and backup bearings being placed inside the rotatable shaft of the vacuum pump. The sensor placements are independent of the bearing position, so that the respective radial sensors can be at the same axial position as the respective radial bearings, which provides sensors co-location and a space saving within a turbopump housing, in particular, in its axial direction, while sensors and mechanical backup bearings are placed in a better protected area with respect to pumped corrosive gases.