Abstract: A high resolution NMR signal is obtained for a thin slice through a body by combining signals in which excitation k-space is covered in two or more excitations. An RF excitation pulse is applied along with an oscillating (e.g. triangular, trapezoidal, sinusoidal) wave modulated magnetic gradient with the RF pulse having nulls corresponding to zero values of the gradient. The RF pulse is applied a second time with the magnetic gradient inverted NMR signals detected following the application of the RF excitation pulses are summed. Minimum phase RF pulses can be employed to reduce signal dropout and reduce artifacts.

Abstract: A fast spin-echo NMR pulse sequence is modified to produce a pair of gradient recalled echo signals between each successive pair of RF refocusing pulses. The first gradient recalled echo signal in each pair is acquired and employed to reconstruct a first image and the second gradient recalled echo signal in each pair is employed to reconstruct a second image. The two gradient recalled echo signals in each pair are separately phase encoded such that the two reconstructed images having contrasting T.sub.2 -weighting.

Abstract: Method and apparatus for detecting the presence of gaseous nitrogen dioxide and determining the amount of gas which is present. Though polystyrene is normally an insulator, it becomes electrically conductive in the presence of nitrogen dioxide. Conductance or resistance of a polystyrene sensing element is related to the concentration of nitrogen dioxide at the sensing element.

Abstract: Apparatus and methods for determining the liquid/liquid interfacial tension between immiscible liquids wherein a first liquid is introduced into a second liquid at a constant rate of flow sufficient to produce successive, uniform size drops which ascend or descend depending upon whether the first liquid has a lower or higher density than that of the second liquid. The apparatus and methods are particularly useful in evaluating the effectiveness of a surfactant and the dynamics of interfacial reduction. In practice, the first liquid is discharged into the second liquid through a nozzle having an outlet of very low surface area. The time required to produce a selected number of drops is inversely proportional to the ability of the surfactant to reduce interfacial tension between the two liquids.

Abstract: The velocity of a fluid in a positive or negative direction is measured by se of a thermistor in a feedback circuit. The temperature of a flow thermistor is balanced with the temperature of a reference thermistor by sensing temperature through resistance by way of its voltage and adding power until the flow thermistor is at the same temperature as the reference thermistor. The ratio of reference power used as compared to flow power is indicative of the fluid's speed. Power is added by sending a signal of varying frequency to the flow thermistor; the reference thermistor is powered by a constant frequency signal. Power is measured by comparing the frequencies of the reference signal to the flow signal. Fluid direction is measured by placing a direction thermistor on either side of the flow thermistor, measuring the temperature of each direction thermistor, the cooler thermistor being upstream of the flow thermistor.

Abstract: A method of determining the proportions of different components of material in a duct comprises exciting nuclear magnetic spins of nuclei of a species common to the components in a region of the duct and utilizing the resulting free induction decay (FID) signal. The nuclear spins are excited simultaneously in the components and the proportions are determined by measuring the phase of the FID signal relative to a phase datum. The method finds particular application for measuring the proportions of oil and water in material obtained from a sub-sea oil well.

Abstract: The invention relates to a process and device for measuring the effective viscosity and the elastic properties of coatings. Known measuring processes and measuring devices based on the "rolling ball method" suffer from drawbacks, namely run formation and sinking of the relatively heavy solvent vapors, due to the inclination of the coated sheet metal. To overcome these drawbacks, rolling movements are imparted to a magnetizable ball (1) displaced from its rest position in a magnetic field, during movement of the horizontally disposed substrate, under the influence of the field gradient of a permanent magnet or electromagnet (4) located below the substrate. The rolling movements are used as the basis for the measurements.

Abstract: A resonator is provided for electron spin resonance spectroscopy. The resonator comprises walls defining a cavity. In the cavity, a predetermined oscillation mode of a preselectable frequency, in particular in the Q band, is capable of propagating. The walls are provided with an opening for irradiating a radiation, in particular light rays. The cavity has a cylindrical shape. An oscillation mode of the type TE.sub.01n is excited, with n being greater than one. The opening is configured as an annular slot extending substantially all around the cylindrical jacket, which defines the cavity, in a radial plane at a distance of m L/4 from a radial end wall delimiting the cavity, and m is an odd number and greater than one (FIG. 2).

Abstract: A multiple-pulse RF pulse sequence applied in the presence of an oscillating magnetic field gradient enables slice selection in a magic angle spinning nuclear magnetic resonance solids imaging system. Slice selectivity is produced by a series of RF pulses, some of which introduce a nutation that coherently adds for only a selected slice plane of the sample and averages to zero in other areas and some of which average certain gradient-induced modulations so that only those object areas in the selected slice contribute to the output. The pulse train is applied in a manner synchronous with rotor rotation so that rotation induced modulations average to zero over one or more rotor rotation periods.

Abstract: A real-time control system for use with an NMR spectrometer. The control system comprises a control section, a plurality of functional units controlled by the control section, and a bus line connecting the control section with the functional units. Each functional unit has a memory storing event data specifying the conditions of control means such as gates included in the functional unit. The control section has a memory storing timing data and event codes specifying event data. The control section successively produces timing signals and event codes according to the timing data. The timing signals are transmitted to the functional units over the bus. Each functional unit reads event data from its memory according to the incoming event codes and controls its gates according to the event data in synchronism with the timing signals.

Abstract: A system and method for detecting a class of explosives and narcotics containing nitrogen in a specimen by nuclear quadrupole resonance which improves the selectivity, sensitivity and spatial localization over conventional detection systems. As a result, sub-kilogram quantities of explosives and narcotics against a background of more benign materials may be detected by the nuclear quadrupole resonance system and method. Also, by the use of a meanderline surface coil, the electrical and magnetic fields will fall off rapidly over a short distance so that a localized region may be scanned and people may be scanned without depositing substantial RF power into the body. Furthermore, by using a strong off-resonance comb (SORC) irradiation sequence, the signal-to-noise ratio of the detected signal is improved for obtaining a more accurate detection signal from the specimen.

Abstract: A three dimensional image of a human brain or other body structure is constructed using a single flow sensitive data array and a flow insensitive data array to generate the contrasts necessary to differentiate among stationary tissues and also between stationary tissues and flowing blood. A plurality of data points from this combined image data are identified to tissue types and used to segregate the remaining data by using a nearest neighbor process in which each data value takes the tissue type of its nearest neighbor data point.

Abstract: A tesseral gradient coil for use in a nuclear magnetic resonance tomography apparatus is disposed in the hollow-cylindrical interior of the magnet system which generates the fundamental magnetic field, with one segment of each turn of the gradient coil lying on a small radius and one segment lying on a large radius, with reference to the cylinder access. The parasitic magnetic field which is unavoidably generated by the gradient coil, and which induces currents in the examination subject and in the cryostat of the fundamental field magnet system, is significantly reduced by this coil arrangement. The structure of the gradient coil is particularly suitable for use in the echo planar method, wherein the gradients must be switched rapidly and induced currents are therefore especially disturbing.

Abstract: In the present invention a method is disclosed to correct the asymmetry in an NMR radio frequency coil of the type that has a pair of conductive loop elements disposed in a spaced apart relation along a common longitudinal axis. The coil has at least eight conductive elements electrically interconnecting the loop elements at point spaced along the periphery of each of the loops. A pair of corrective capacitive elements are placed 45.degree. apart from one another and in series with a pair of the conductive segments which interconnect the loops. The present invention also relates to an NMR radio frequency coil having N-fold symmetry and reduced eddy current.

Abstract: A method for chemical shift imaging is disclosed. A first radio frequency pulse at the resonance frequency of hydrogen and second radio frequency pulse at the resonance frequency of atoms to be examined are applied. Spatial resolution is obtained by phase encoding gradients. The repetition time is shorter than the spin-lattice relaxation time. The first radio frequency pulse at the resonance frequency of hydrogen causes a Nuclear Overhauser Effect enhancement of the resonance line of the atoms to be examined.

Abstract: A method and an apparatus for examining and determining the viscosity of a liquid sealed in a container by applying a centrifugal force to the container, detecting a change in the surface form of the liquid with a sensor, and measuring either a lapse of time from the application of centrifugal force to the time when the output voltage of the sensor reaches a predetermined level or a voltage output of the sensor upon a predetermined lapse of time from the application of a centrifugal force, thereby examining and determining the viscosity of the liquid to find out whether there is any quality change in the liquid without destroying the container.

Abstract: A magnetic resonance imaging apparatus comprising device for applying a magnetic field to a sample to be imaged, device for applying pulses of MR transition-exciting electromagnetic radiation to the sample, an NMR signal coil for detecting the resulting radiation from the sample, and device for appling pulses of electromagnetic radiation to the sample for stimulating coupled ESR transitions, in which a pulse generating device is coupled to the NMR signal coil and antennas are coupled to the coil and disposed at plural positions along the coil, whereby pulses for stimulating coupled ESR transitions may be transmitted from the pulse generating device through the coil to the antennas and thence into the sample, the antennas being arranged to give a predominantly magnetic coupling to the sample.

Abstract: In a method and an apparatus for balancing successive rotary members, an unbalance measuring operation is carried out in one or more planes on each rotary member which is rotated at a measuring speed in a measuring run within an overall unbalance measuring time for ascertaining the required number of items of measuring information in a plurality of repetitive measuring cycles. After the elapse of a fraction of the overall unbalance measuring time the unbalance measuring operation is interrupted for an interruption time for the purposes of permitting the performance of working operations which due to vibration caused thereby could result in falsification of the unbalance measurement results, then unbalance measurement is resumed, and further interrupted, and so on in a repetitive procedure to make up the overall measurement time.

Abstract: An assembly for testing the inner diameter of a rifled barrel of a firearm and a method of manufacturing the same. The assembly has a frame with side air discharge apertures and is intended to be connected to an air gauge. The assembly has a timing sleeve that is removably mounted to the frame such that the sleeve can be replaced when it becomes worn or when the assembly is intended to be used with a barrel having a different type of rifling. The assembly also comprises a wear ring such that the wear ring and timing sleeve absorb abrasive contact in the barrel to reduce abrasive contact by the barrel on the frame.

Abstract: A device and a method are provided for reducing false indications of leakage between the inner and outer walls of a double-wall tank. The device reduces contact between a sensor assembly and condensation which forms between the walls, preferably comprising an isolation stand-off flange secured around a portion of the sensor assembly. The method comprises spacing the sensor assembly from the walls to reduce the potential for contact between the sensor assembly and condensation.