Showing papers in "Journal of Magnetic Resonance in 2012"

TL;DR: In comparison with designs which irradiate perpendicular to the rotation axis the approach used here provides a highly efficient use of the incident microwave beam and an NMR-optimised coil design.

TL;DR: Experimental data of MAS-DNP enhancements of (1)H and (13)C in proline and SH3 protein in glass forming water/glycerol solvent containing TOTAPOL is shown and a theoretical model that aims at explaining how the nuclear polarization is built in MAS- DNP experiments is introduced.

TL;DR: A 1 ns resolution pulse shaping unit has been developed for pulsed EPR spectroscopy to enable 14-bit amplitude and phase modulation and the concept of a dead-time compensated prefocused pulse has been introduced to EPR with a self-refocusing of 200 ns after the end of the pulse.

TL;DR: Studies on several representative compounds demonstrate that this goal can be implemented in a robust format, provided that suitable care is also taken to suppress unwanted coherences, of making all manipulations sufficiently broad-banded and to provide adequate heteronuclear decoupling of the targeted protons.

TL;DR: The Non-Hydrogenative Parahydrogen-Induced Polarization (NH-PHIP) technique, which is referred to as Signal Amplification by Reversible Exchange (SABRE), has been reported to be applicable to various substrates and catalysts.

TL;DR: A systematic study characterizing the achievable performance of 90° and 180° universal rotation pulses as functions of bandwidth, pulse length, and tolerance to B(1)-field inhomogeneity/miscalibration finds that the application of a single optimal refocusing pulse matches or improves the performance of two consecutive inversion pulses in INEPT-like pulse sequence elements of the same total duration.

TL;DR: This review summarizes recent spectroscopic developments to access structure and dynamics of biomacromolecules in the solid-state, and shows a number of applications to amyloid fibrils and membrane proteins.

TL;DR: It is shown that BRAIN-CP can be combined with broadband frequency-swept versions of the Carr-Purcell-Meiboom-Gill experiment and provides multiplicative signal enhancements of both CP and multiple-echo acquisition over a broad frequency region.

TL;DR: Two-dimensional spectra of a model system demonstrate that the higher field provides excellent resolution, even in a glassy, cryoprotecting matrix, and a strong microwave power dependence suggests the possibility for considerable improvement.

TL;DR: These tools for enriching and quantifying parhydrogen have been in steady use for 3 years and should be helpful as a template or as reference material for building and operating a parahydrogen production facility.

TL;DR: It is found that the rate of sample freezing affects mainly the ensemble of spin-label rotamers, but the distance maxima remain essentially unchanged, which suggests that proteins frozen in a regular manner in liquid nitrogen faithfully maintain the distance-dependent structural properties in solution.

TL;DR: A Comprehensive Multiphase-Nuclear Magnetic Resonance (CMP-NMR) probe has been developed, and is introduced here, that permits all bonds in all phases to be studied and differentiated in whole unaltered natural samples, possessing a great potential for the in situ study of natural samples in their native state.

TL;DR: In this paper, the authors describe the design and implementation of a tunable 250 GHz gyrotron oscillator with >10 W output power over most of a 3 GHz band and >35 W peak power.

TL;DR: A shimming approach useful to reduce the gradient strength of the magnetic field generated by single-sided sensors simultaneously maximizing its uniformity along the lateral directions of the magnet by implementing this method on a standard U-shaped magnet.

TL;DR: It is shown that compressed sensing can be applied to reduce the acquisition time by a factor of 2 at 7 T without losing sodium quantification accuracy, and the nonlinear reconstruction technique can be used to denoise fully-sampled images.

TL;DR: The application of NUS for the measurement of one-bond scalar and residual dipolar coupling constants from different kinds of ω(1)-coupled spectra (including also J-scaled ones) is examined in detail and the possible gains in time or resolution are discussed.

TL;DR: This work investigated the effects of biradical concentration on the relaxation, enhancement, and intensity of NMR signals, employing a series of samples with various TOTAPOL concentrations and uniformly (13)C, (15)N labeled proline.

TL;DR: Numerical simulations and experimental results demonstrate that two-frequency rf irradiation can flatten out MT asymmetry when both frequency components lie within the spectrum of an MT pool, and a strategy is proposed to isolate chemical exchange saturation transfer (CEST) contrast fromMT asymmetry contrast by using the two- Frequency irradiation technique.

TL;DR: It was determined that the use of low sample temperature and high external field is generally rewarding for the total sensitivity, in spite of the slower polarization buildup at lower temperature and lower DNP efficiency at higher field.

TL;DR: It is demonstrated that the gamma distribution is by far superior to the log-normal, and comparable to the two other models, in terms of computational speed, and is particularly striking for multi-component signal attenuation.

TL;DR: It is demonstrated that the described resonator has superior concentration sensitivity as compared to commercial pulse Q-band resonators, especially for pulse EPR experiments of low concentration biological samples.

TL;DR: The design and initial performance results of a multi-sample dissolution dynamic-nuclear-polarization (DNP) polarizer based on a Helium-temperature NMR cryostat for use in a wide-bore NMR magnet with a room-tem temperature bore are described.

TL;DR: Calculations of the spin dynamics with the density matrix formalism support the experimental findings, providing profound understanding of the experiments in Cs-symmetric molecules.

TL;DR: Close to unity polarization is obtained for all molecules and sequences and the loss of polarization caused by erroneous B(1) and J-coupling constants is reduced by choosing the channel and phase of some pulses in the SOT sequences appropriately.

TL;DR: The accuracy and robustness of two compressed sensing algorithms: convex and non-convex (iterative soft thresholding anditeratively re-weighted least squares with local ℓ(0)-norm) in application to two- and three-dimensional datasets are discussed.

TL;DR: It is shown that with a cryogenically cooled NMR probehead, a high spin-lock field strength can be generated that is able to detect motions as fast as 25 μs, and relaxation dispersion for a residue that undergoes smaller chemical shift variations due to dynamics was identified.

TL;DR: This work investigates to which extent the sinc-shaped frequency excitation profiles of the pulse can be used for imaging without the generation of artefacts and proposes a correction algorithm that eliminates the influence of the excitation profile.

TL;DR: These results demonstrate how limitations imposed by linear response theory may be vastly exceeded when using a sufficiently accurate system model to optimize pulses of high complexity.

TL;DR: New modifications of the optimal control algorithm that incorporate symmetry principles (S-BURBOP) and relax conservative limits on peak RF pulse amplitude for short time periods that pose no threat to the probe are presented.

TL;DR: This work demonstrates the use of a 1.1 T bench-top NMR magnet, which when coupled with an rf micro-coil, is able to provide sufficient chemical shift resolution such that unambiguous signal selection is achieved from the dispersed droplet phase.