Abstract: A system, method and computer program product for detecting indicators for structural changes of NMR active test molecules in a test sample, or indicators for structural changes of the environment of said test molecules in relation to a reference molecule. Initial local similarity values are obtained, using a similarity function and representing a local similarity between a reference spectrum and a test spectrum within corresponding similarity regions (SRR, SRT). The initial local similarity values represent a similarity map (SM1) in which contours of a first shape type are indicators (I1) for structural changes of the test molecule, and in which contours of a second shape type are indicators (I2) for structural changes of the environment of said test molecule in relation to the reference molecule.

Abstract: A method for determining an electric current includes sending the electric current to be measured through a shunt arrangement that includes at least three identical resistors. The at least three identical resistors are thermally coupled to a common base plate and are electrically interconnected such that the electric current is at least partially divided such that a first local current through a first resistor is not equal to a second local current through a second resistor. The method also includes measuring, at the shunt arrangement, a first voltage and a second voltage via which the voltage dropping across a first resistor and across a second resistor are directly or indirectly determinable, and determining the electric current via the first voltage and the second voltage. A heating in the shunt arrangement generated by the electric current is at least partially taken into account in the determining the electric current.

Abstract: An apparatus for collecting liquid fractions from a separation/reaction apparatus (1). A capillary (2) guides an extracted liquid fraction to a branching unit (3), a collection arrangement (4) carries a plurality of target vessels (5) receiving the liquid fraction from the capillary and a fluid line (6) is flow-connected to a fluid pump (7) and opens into the branching unit. The capillary and the fluid line each have outlet openings in the direct vicinity of one another at their end facing a target vessel such that liquid emerging from the outlet opening (2?) of the capillary transitions into the outlet opening (6?) of the fluid line. This precludes back mixing with earlier/later liquid fractions, precludes uncontrolled dripping of sample substance at the transfer point, speeds displacement of the target vessels in the collection arrangement, facilitates automation of the fraction processing procedure, and results in a more compact fraction collection apparatus.

Abstract: An MAS probehead (1) positioned in a magnet bore (2) includes a sample chamber (3) with a stator (4) for receiving a rotor and an RF coil that radiates RF pulses into and/or receives RF signals from an NMR sample (5). A temperature-control apparatus guides gas at a first variable temperature T1 into the sample chamber and through the stator during an NMR measurement, and guides a pressurized gas stream at a second variable temperature T2 around the sample chamber. The sample chamber is surrounded by an encapsulation device (6), at least in the azimuthal direction around the axis of the magnet bore and counter to the flow direction of the pressurized gas, and is oriented to provide an air gap (7?) between the sample chamber and the magnet bore. This prevents dissipation of the gas temperature to outer parts of the probehead, and yields larger NMR measurement temperature ranges.

Abstract: A magnet arrangement having a hollow-cylindrical magnet element that has an axial length Lz,M and an inner radius Rin, is constructed from magnet segments arranged concentrically around the z-axis, and has a Halbach magnetization. At least one ring-shaped magnet element has a notched, hollow-cylindrical cutout extending circumferentially around the z-axis symmetrically with respect to the plane z=0, the axial extent Lz,A of the cutout being less than the axial length Lz,M of the magnet element. The cutout has a radial depth TA and an axial length Lz,A<Lz,M between the z-positions z=?zA to z=+zA. The radial depth TA and the axial length Lz,A of the cutout are to ensure that the remaining inhomogeneity of the homogenous magnetic field B0 in a predefined measurement volume having an axial plateau length LP in the center of the magnet arrangement does not exceed 10 ppm.

Abstract: A monitoring device is provided for analytical measurement of reaction fluid produced in a reaction vessel in a spectrometer with a monitoring cell. The distribution apparatus includes at least four supply and return lines that open into the distribution apparatus, wherein the distribution apparatus comprises a distribution device for distributing reaction fluid to the supply and return lines. The distribution apparatus comprises a distribution vessel in which the distribution device and an electrically controllable pump device for pumping of the reaction fluid are provided, wherein the distribution device comprises an electrically controllable valve device for distributing the reaction fluid to the lines that open into the distribution vessel.

Abstract: A system including an NMR spectrometer (1) with a flow cell (2) analyzing a first liquid test sample (P1), a distributing device (3) with a multi-way valve, plural assemblies interconnected via fluid lines through the distributing device, a cannula (5) taking test samples from a storage vessel (5a), a sample loop (6) temporarily storing a further test sample (P2), and a pump device (7) pumping liquid (S) into the system. The valve arrangement a) decouples the sample loop with the temporarily stored further test sample and, simultaneously, b) decouples the flow cell with the first test sample from all fluid lines to the distributing device; and c) connects the cannula to the pump device for a simultaneous purging step or to the flow cell for removing the first test sample into a receiving vessel (5b; 5c) or to the sample loop for receiving a subsequent test sample.

Abstract: An NMR probe head (1) having an RF coil arrangement (2a) in a coil region (2) and an RF shielding tube (3) for supply lines leading from a connection region (4) to the coil region. An elongated backbone (5) is arranged inside the shielding tube and has an inherently rigid, mechanically stiff structure having continuous bores and/or connecting channels (5a) which run parallel to the tube axis and accommodate the supply lines. The backbone has a continuously electrically conductive outer surface which leads from the connection region to the coil region and is electrically conductively connected to the conductive inner surface of the shielding tube via connecting elements (6). A continuous electrically conductive contour is formed thereby between the backbone and the shielding tube. This shields against externally incident RF fields and spatially separates the stable mechanical supporting construction and the supply lines from the electronic and RF components.

Abstract: A probe head (1) of an NMR-MAS assembly has a stator (2) with an opening (4) receiving a rotor (3) which, in a measuring position, rotates at the magic angle to the B0 field. The stator is pivotable between the measuring position and a loading position of the rotor. A detection device (5) permits external, contactless identification of whether the opening of the stator is fitted with a rotor. The detection device has a light source (5a), from which light is introduced into a lower end (6?) of a light guide (6). The stator has a first bore (2a), in which a first light guide stump (7a) is positioned such that, in the loading position of the stator, it produces an optical connection between a rotor inserted in the stator and an upper end (6?) of the light guide opposite the lower end.

Abstract: An EPR resonator for a cylindrical TE01n microwave mode, where n=1, 2, 3, or 4, has: a cylindrical body (10) which has an RF absorption of less than 5% at RFs below 1 kHz, a first plunger (11) delimiting the resonating volume within the body in an axial direction at a first end and a second plunger (12) delimiting the resonating volume within the body at a second end, the second plunger having an opening (13) for inserting an EPR sample. The first and second plunger each has a spiral winding of an electrically conductive filament wherein neither the ends nor neighboring turns of the spiral windings have electrically conductive connections prone to forming electrically closed loops. Using spiral winding plungers for cylindrical TE01n microwave modes provides equivalent functionality compared to conventional plungers, but without creating Eddy currents at frequencies lower than the frequency of the TE01n microwave mode.

Abstract: An NMR-MAS probehead having an MAS stator (3) receiving an MAS rotor (5) that is surrounded by an RF coil (4) and that has a sample substance, and having a first microwave guide (1) supplying microwave radiation into a sample volume (0) through a coil block (2). The coil block is constructed from dielectric material, is inserted into the wall of the MAS stator so that it surrounds the RF coil and the MAS rotor, and has a first bore (4?) that extends coaxially with the longitudinal axis of the elongate MAS rotor, the RF coil being fastened to the inner wall of said first bore, as well as a second bore (8?) that extends coaxially with the longitudinal axis of the first microwave guide and has a hollow, elongate second microwave guide (8) supplying microwave radiation from the first microwave guide into the sample volume.

Abstract: A magnet arrangement (1) having a permanent magnet system with at least two ring-shaped magnet elements (2) which are made of individual magnet segments (3), are arranged cylindrically symmetrically and stacked on one another in the z direction and/or concentrically, and arranged such that the magnetization directions of the individual segments in the rings extend parallel in an x-y plane. The magnet elements align relative to one another in the z direction and have a Halbach magnetization Before final mounting in the magnetic resonance apparatus, the magnet elements are prefabricated as solid structures and their respective magnet segments are fixed undisplaceably relative to one another. But the magnet elements are displaceable relative to one another in the x-y plane, and are mounted rotatably and/or tiltably relative to one another.

Abstract: Systems and methods for improved NMR signal detection are described. The system receives NMR signal data produced by a sample over time in response to an excitation pulse and selects a predefined system function for application to the NMR signal data for systematic variation of signal properties The system function has a different influence on NMR signal components than on noise components of the sampled signal and has a variation parameter to control the systematic variation. A plurality of variation parameter values is provided with differing values to influence broad NMR signals as well as weak NMR signals. The system generates for each variation parameter value a corresponding intermediate data set by applying the system function with the respective variation parameter value to the NMR signal data. Further, from each intermediate data set, a respective base value centered spectrum is generated in the frequency-domain.

Abstract: A high-frequency interface circuit to direct transmitted signals to a connector (PR) for a HF arrangement in a transmit mode via an input (TX) of the high-frequency interface circuit and received signals from the connector (PR) to a receiver system in a receive mode via an output (RX) of the high-frequency interface circuit is presented. The circuit includes a transmit path (SP) linking the input (TX) to the connector (PR) and a receive path (EP) linking the connector (PR) to the output (RX). The receive path (EP) includes a first circuit (K1), with at least a first switching element (S1) that is electro-conductive in transmit mode and is electrically insulating in receive mode, connected to the connector (PR). In transmit mode, the first circuit (K1) forms two parallel resonance circuits connected in series, while in receive mode, the first circuit (K1) includes two series resonance circuits connected in parallel.

Abstract: A method for operating an NMR probehead (10) with an MAS stator (11) receiving a circular-cylindrical hollow MAS rotor (13) with an outer jacket. The MAS rotor is mounted on pressurized gas in a measuring position within the MAS stator via a gas supply device with a bearing nozzle (12?) and rotates about the cylinder axis of the MAS rotor at a rotation frequency f?30 kHz. During a measurement, a temperature control gas is blown by a temperature control nozzle (12) onto the outer jacket of the rotor at an angle ?<90° with respect to the longitudinal axis of the cylinder-symmetrical rotor. The flow speed of the temperature control gas corresponds in the nozzle cross section to at least half the circumferential speed of the outer jacket of the rotating rotor and to at most the speed of sound in the temperature control gas.

Abstract: A magnetic resonance (MR) device, having a gradient arrangement that includes a gradient coil (G) with an internal resistance (Rg), as well as an electric circuit for generating variable pulse-shaped currents through the gradient arrangement. The electric circuit has at least one low-voltage voltage source (V) for generating a voltage U?100V, and a first circuit section in the electric circuit for current in the gradient coil in one direction and a second circuit section in the electric circuit for current in the gradient coil in a reverse direction to the first circuit section. This permits the generation of accurate square-wave current pulses, with a simultaneously short charging time of the auxiliary inductance.

Abstract: Correlation information between captured characteristics and chemical shift values of captured NMR spin systems is provided by a model appliance for a fluid class. An NMR spectrum of a sample of the fluid class is recorded. Peaks in the recorded NMR spectrum which belong to defined reference NMR spin systems are identified, and experimental chemical shift values of the peaks from the recorded NMR spectrum are determined. A chemical shift value of at least one of the captured NMR spin systems not belonging to the reference NMR spin systems is predicted by applying the model appliance onto the experimental chemical shift values of the reference NMR spin systems. Peaks in an NMR spectrum of a sample of a fluid class are attributed more quickly and reliably to NMR spins systems of compounds contained in the sample.

Abstract: A superconducting magnet coil arrangement has a high-temperature superconductor (HTS) coil section (1a,1b,1c) in the form of a solenoid that is wound with an HTS tape conductor, and also has a field-shaping device comprising at least two field-shaping elements (2a,2b,2c). At least one respective field-shaping element is arranged adjoining each of the two axial ends of the HTS coil section, the field-shaping elements being configured in such a way that they reduce the field angle of the magnetic field generated by the magnet coil arrangement with respect to the axial direction in the region of the HTS coil section by at least 1.5°.

Abstract: A microwave resonator for an EPR probe head has a metal cavity body (1) supporting an electromagnetic microwave resonance mode. The metal cavity body (1) has an opening for inserting a sample tube (2) to a center position of the resonator. The center of the opening and the center position of the resonator define an x-axis. The cavity body also has an opening for transmitting microwave radiation into the resonator. Two dielectric elements (4a, 4b) are located symmetrically to the E-field nodal plane containing the x-axis and a z-axis perpendicular to the x-axis. Each dielectric element is geometrically formed and positioned such that it provides an equal overlap with a local maximum of the microwave electric field energy. The microwave resonant cavity has a thin planar shape and the resonator is loaded with two dielectric elements, placed symmetrically relative to the central EPR sample.

Abstract: A spectroscopic method for calculating a limit of quantification and a relative error includes: 1. selecting an error function F(C); 2. providing a blank spectrum; 3. recording a reference spectrum with a signal content of the substance being investigated; 4. determining start concentrations; 5.a. multiplying the reference spectrum with the signal content of the substance by a factor; 5.b. adding the resulting spectrum to the blank spectrum and determining the corresponding concentration of the substance and calculating the corresponding relative error; 6. iteratively adapting parameters of the selected error function F(C): recording a measurement spectrum of the test sample and determining the concentration of the substance being investigated using 5.b. and comparing with the calculated limit of quantification and calculating the relative error by applying the error function from step 6.