Abstract: The present invention relates to a parallel rheometer and improved force sensor elements, which may advantageously be used in combination with the parallel rheometer. The parallel rheometer of the present invention allows simultaneous measurements of a plurality of samples so as to allow characterization of a plurality of samples within a short time period. The force sensor element according to the present invention allows simultaneous measurement of a shear force and a normal force applied to the sensor element. Moreover, the force sensor may employ stress-optic material.

Abstract: The present invention discloses an apparatus and method for rapid analysis of members of a combinatorial library. The apparatus includes a plurality of vessels for containing individual library members and a fluid handling system that apportions a test fluid about equally between each of the vessels. This allows for simultaneous screening of library members by detecting changes in test fluid following contact with individual library members. Fluid flow through each of the vessels is controlled using passive flow restrictors or active flow controllers to ensure that each library member contacts approximately the same amount of test fluid per unit time. The disclosed apparatus is especially useful for screening library members based on their ability to catalyze the conversion of fluid reactants.

Abstract: An apparatus and method for screening combinatorial libraries of materials by measuring the response of individual library members to mechanical perturbations is described. The apparatus generally includes a sample holder for containing the library members, an array of probes for mechanically perturbing individual library members, and an array of sensors for measuring the response of each of the library members to the mechanical perturbations. Library members undergoing screening make up a sample array, and individual library members constitute elements of the sample array that are confined to specific locations on the sample holder. During screening, the apparatus mechanically perturbs individual library members by displacing the sample array (sample holder) and the array of probes. Typically, all of the elements of the sample array are perturbed simultaneously, but the apparatus also can also perturb individual or groups of sample array elements sequentially.

Abstract: Gas chromatographs of the invention generally comprise four or more analysis channels. Specifically, four or more gas chromatography columns are configured for parallel analysis of four or more gaseous samples with detection being effected using a microdetector array comprising four or more microdetectors. In one embodiment, the four or more microdetectors 510 are microfabricated detectors, and are integrally formed with a substrate or with one or more microchip bodies mounted on a substrate. In a preferred embodiment, a microdetector array comprises four or more thermal conductivity detectors having one or more thin-film detection filaments. A preferred heated environment for highly parallel gas chromatographs is also disclosed.

Abstract: An RF coil with high signal-to-noise (S/N) and B1 homogeneity over the volume originating from the arctic arch and extending to the top of the head, which is highly desirable for quantitative (anatomical, vascular and functional) studies in-vivo. The coil is suitable for use in performing multiple studies and reducing scan time without patient repositioning. Moreover, the coil is capable of imaging in different operating modes. A split-top design is used to ease patient access.

Abstract: The present invention discloses an apparatus and method for rapid analysis of members of a combinatorial library. The apparatus includes a plurality of vessels for containing individual library members and a fluid handling system that apportions a test fluid about equally between each of the vessels. This allows for simultaneous screening of library members by detecting changes in test fluid following contact with individual library members. Fluid flow through each of the vessels is controlled using passive flow restrictors or active flow controllers to ensure that each library member contacts approximately the same amount of test fluid per unit time. The disclosed apparatus is especially useful for screening library members based on their ability to catalyze the conversion of fluid reactants.

Abstract: An RF coil array which includes first and second RF coils that are overlapped to eliminate their coupling (to maintain zero mutual inductance between them) through space, a third coil connecting the first and second coils such that there is no net coupling between the first two coils through the third coil, and in which all three coils are well isolated from one another at the resonance frequency or frequencies of interest.

Abstract: A less-claustrophobic, quadrature, radio-frequency head coil (42) includes first and second broken end rings (90, 92) connected to each other in parallel by a plurality of leg conductors (94). At least two of the leg conductors are interconnected by a third arcuate conductor segment (98) axially displaced from planes of the first and second end rings to provide an opening (44) over a subject's face. The opening reduces patient claustrophobia and permits access to the patient for life-support devices or the practice of interventional medicine. The end rings have a fixed capacitance (C.sub.1, C.sub.2) between each pair of leg conductors. The fixed capacitance C.sub.1 between at least one pair of leg conductors and the fixed capacitance C.sub.2 between at least the pair of leg conductors adjacent the opening, where C.sub.2 >C.sub.1. A two-port feed (66, 68) circumferentially attached to the coil generally opposite the opening matches the individual linear modes.

Abstract: An RF coil which includes an RF coil primary, an RF coil secondary, and coupling impedances that connect the two at several points along the coil peripheries. The coupling impedances are primarily reactive, and may be fixed or variable, depending on the purpose of use.

Abstract: An RF coil which includes an RF coil primary, an RF coil secondary, and coupling impedances that connect the two at several points along the coil peripheries. The coupling impedances are primarily reactive, and may be fixed or variable, depending on the purpose of use.

Abstract: A magnetic resonance system is used to excite high .gamma. dipoles, such as hydrogen, and lower .gamma. dipoles, such as phosphorous, to resonate concurrently. A multiply-tuned radio frequency coil (40) is disposed around the region of interest. The multiply-tuned radio frequency coil is tuned to the resonance frequency of the high .gamma. dipoles and the resonance frequency of the low .gamma. dipoles. The coil has an inner coil section, defined by a first leg or ring (92) and a second leg or ring (94), which is tuned by added capacitance substantially to the resonance frequency of the low .gamma. dipole. A first outer coil section which is defined by a third leg or ring (90) and the first leg or ring. A second outer coil section defined by the second leg or ring (94) and a fourth leg or ring (96). The first and second outer sections, together with the inner coil section define a coil which has a co-rotating mode and a counter-rotating mode.

Abstract: A coil assembly (40) includes a first, birdcage type head coil assembly (42) dimensioned to receive a patient's head and a second, neck coil assembly (44) including an anterior coil portion (44a) and a posterior coil portion (44b) dimensioned to receive the patient's neck region. The head and neck coils are partially overlapped. A first cable extends (98a) from the anterior coil portion past the birdcage head coil assembly and a second coaxial cable (98b) extends from the posterior portion past the birdcage head coil assembly. A first decoupling circuit (104a) is disposed in the first coaxial cable beyond a guard ring (106) and a second decoupling circuit (104b) is disposed in the second coaxial cable adjacent the region of overlap between the head and neck coil assemblies. The decoupling circuits are positioned and tuned to prevent radio frequency communication along the coaxial cable sheath between the head and neck coil assemblies.

Abstract: In a magnetic resonance imaging apparatus, a radio frequency coil (40) is disposed closely adjacent the patient's head. The radio frequency coil includes a first annular ring (80, 114) around the patient's head from which a first plurality of legs (82, 116) extend. Opposite legs are interconnected equidistant from the first annular ring to form a virtual ground connection (84, 118). In the embodiment of FIG. 6, a second annular ring (120) is disposed parallel to the first annular ring with a second plurality of legs (122) extending between the first and second annular rings. By adjusting a ratio .rho. of the current flow in the loops defined by the first legs, the first annular ring and virtual ground relative to the current loops defined by the second legs and the first and second annular rings, the linearity of the B.sub.1 field within the head coil is selectively adjustable (FIG. 8).

Abstract: A birdcage coil (42) and a quadrature coil pair which are disposed in a partially overlapping but electrically isolated relationship within a static magnetic field generated by a main field magnet (10). The birdcage coil preferably has twelve legs, has eight-fold symmetry, and is tuned to have two linear modes aligned with first and second orthogonal axes. The quadrature coil includes a first or upper coil portion (90) having an even-number of legs and a mode aligned with a third axis. A second or bottom quadrature coil (92) has an odd-number of legs and has a mode which is aligned with a fourth axis, preferably orthogonal to the third axis. Received resonance signals of the two modes of the birdcage coil are combined (66) and digitized (64); resonance signals received in the first and second modes of the quadrature coil pair are combined (66) and digitized (64).

Abstract: An RF resonator mounted on a dielectric support is operated in quadrature at a selected NMR frequency. The resonator consists of four axially distributed high frequency ring current paths on the support and at least four high frequency current paths interconnect each pair of adjacent ring paths. In the preferred embodiment at least sixteen equally spaced parallel segments connect each ring pair and are aligned with one another. The ring segments between the parallel segments together with the parallel segments form loops. At least one discrete capacitor is placed in each outer current loop thereby interrupting the loop. However, this is done so that no inner loop is interrupted by a capacitor. By using quadrature input/output coupling, either inductive or capacitive, a co-rotating mode is excited in the two outer loops through the inner loops providing a highly uniform field across the resonator.

Abstract: A radio frequency volume resonator mounted on a generally cylindrical dielectric support can be operated in quadrature at one or more NMR frequencies. The resonator consists of four axially distributed high frequency ring current paths and a dielectric support, at least four high frequency current paths interconnect each pair of adjacent ring paths, at least one discrete capacitor is placed in each current loop but arranged so that none of the ring current paths is interrupted by a capacitor.

Abstract: A radio frequency volume resonator mounted on a dielectric support can be operated in quadrature at one or more NMR frequencies. The resonator consists of four axially distributed high frequency ring current paths on the dielectric support. At least four high frequency current paths interconnect each pair of adjacent ring paths. The ring segments with interconnecting segments form loops. At least one discrete capacitor is placed in each loop.