Showing papers in "Journal of Magnetic Resonance in 1998"

TL;DR: Dipolar couplings obtained from differences in the splittings measured in the oriented and isotropic phases are in excellent agreement with dipolar coupling obtained from direct measurement of the splitting or from a conventional E. COSY-type measurement.

TL;DR: Modifications to the WATERGATE method for removing the solvent resonance from H-1 NMR spectra provide narrower noninversion regions and hence enhance the sensitivities of the peaks close to the water resonance.

TL;DR: Variable smoothing is used, determined by iterative feedback in such a way that the smoothing penalty is roughly constant, which can give sharp lines, not broadened more than is consistent with the noise, and in the same distribution it can show a tail decades long without breaking it up into several peaks.

TL;DR: The applicability of this method is demonstrated using synthetic data derived from four proteins representative of different sizes, topologies, and secondary structures, and experimental data measured on the small protein ubiquitin.

TL;DR: A method is presented, using the MR signal to accurately measure the k-space trajectory of the imaging sequence, that allows for correction of gradient hardware imperfections and eddy-current effects in MRI.

TL;DR: Parameters of relevance to oximetry with Overhauser magnetic resonance imaging (OMRI) have been measured for three single electron contrast agents of the triphenylmethyl type, which are stable and water soluble and have good properties for oximetric with OMRI.

TL;DR: A simple calculational strategy is presented that makes use of simulated annealing refinement against the residual dipolar couplings in combination with a grid search, to simultaneously refine the structures and ascertain the magnitude of the axial and rhombic components of the tensor.

TL;DR: It is concluded that the effective gradients in carbonates are typically smaller than gradients of current NMR well logging tools, whereas in many sandstones, internal gradients can be comparable to or larger than tool gradients.

TL;DR: Signal attenuation of water and NAA due to diffusion over the entire range of b values examined is not monoexponential and the extracted ADCs depend on the diffusion time, while the potential of NAA diffusion experiments to probe cellular structure is discussed.

TL;DR: These studies demonstrate that tissue metabolites can be detected and imaged via the water protons using the signal amplification properties of saturation transfer in the presence of water/macromolecule magnetization transfer.

TL;DR: It is concluded that increasing the magnetic field strength increases spectral resolution also for 1H NMR, which can lead to more than linear sensitivity gains.

TL;DR: The results suggest that biochemical markers thus measured may function as a valuable adjunct to histopathology to improve the accuracy of and reduce the time frame required for the diagnosis of human breast cancer.

TL;DR: For the case of magic-angle-spinning sideband amplitudes of isolated spins-1/2, it is demonstrated the superiority of Gaussian spherical quadrature over other orientational averaging methods.

TL;DR: By combination of fast magic-angle spinning (MAS) and detection of the free-induction decay during a rotor-synchronized quadrupolar Carr-Purcell-Meiboom-Gill (QCPMG) train of refocusing pulses, the sensitivity of Quadrupolar-echo MAS NMR spectra for the central transition of half-integer quadrupol nuclei exhibiting largequadrupolar couplings may be significantly enhanced.

TL;DR: The results of automated peak picking of NOESY spectra with AUTOPSY were tested in combination with the combined automated NoESY cross peak assignment and structure calculation routine NOAH implemented in the program DYANA and the quality of the resulting structures was found to be comparable with those from corresponding data obtained with manual peak picking.

TL;DR: It is shown that adiabatic pulses with tangential frequency sweeps and other frequency-modulation functions can be optimized to accomplish 13C and 1H broadband inversion using pulse lengths of 192 and 64 micro(s), respectively, at B1 strengths available with modern high-resolution probes.

TL;DR: A simple and effective method is described for simultaneously measuring dipolar couplings for methine, methylene, and methyl groups in weakly oriented macromolecules.

TL;DR: A model-free analysis of 1H NMRD studies of water in concentrated protein solutions and in semisolid biological samples shows that the dramatic salt effect observed in BPTI solutions is due almost entirely to a slowing down of protein rotation with little change of protein structure.

TL;DR: Simulations indicate that by use of the proposed adiabatic RF pulses rotating frame relaxation rates can be obtained for magnetization vectors aligned at arbitrary angles with the static field.

TL;DR: A new non-Fourier data processing algorithm, the filter diagonalization method (FDM), is presented and applied to phase-sensitive 1D and 2D NMR spectra, and results obtained on complex spectra are promising.

TL;DR: A three-dimensional experiment is described in which NMR signals are separated according to their protonchemical shift, 13C chemical shift, and diffusion coefficient.

TL;DR: This new method combines the high resolution usually achieved by MAS with the advantages of orientational constraints obtained by working with macroscopically oriented samples, and presents the first 1H, 31P, and 13C MAS spectra of uniformly aligned dimyristoylphosphatidylcholine (DMPC) bilayers.

TL;DR: In this article, two T2-independent J-difference lactate editing schemes for the PRESS magnetic resonance spectroscopy localization sequence are introduced, which exploit the dependence of the in-phase intensity of the methyl doublet upon the time interval separating two inversion (BASING) pulses applied to its coupling partner after initial excitation.

TL;DR: The CSA values suggest a revised assignment of the 2-methyl 13C sites in the case of ampicillin, and speculate on a relationship between the chemical shift principal values of many of the 13C and 15N sites and the beta-lactam ring conformation.

TL;DR: An enhanced version of the X (omega1) half-filtered TOCSY experiment for measurement of long-range heteronuclear coupling constants is proposed which yields high-quality spectra with substantially increased sensitivity and resolution.

TL;DR: Two techniques for resolution and sensitivity enhancement are introduced in multiple-quantum (MQ) MAS spectroscopy of rigid solids by combining MAS at moderately fast spinning frequencies with multiple-pulse (MP) dipolar decoupling.

TL;DR: A modification of the TROSY experiment which allows for sensitivity enhancement without introduction of additional delays is presented and results in a signal-to-noise gain of 2 independent of the size of the molecule.

TL;DR: The results demonstrate that the 1H and 31P shifts in TmDOTP5- are highly sensitive to temperature and may be used for NMR thermometry with excellent accuracy and resolution.

TL;DR: In this paper, convection artifacts in gradient-enhanced nuclear magnetic resonance spectroscopy are compensated by using modified pulse and gradient sequences. But the principle of convection compensation is applicable to a wide variety of gradientenhanced NMR experiments, in particular those where the interval between a defocusing and a refocusing pulsed field gradient is relatively long.

TL;DR: Applications are discussed of a novel NMR device, the NMR MOUSE (mobile universal surface explorer), for characterization of polymers, and the signal-to-noise ratio (SIN) can be improved by use of steady-state free precession pulse sequences modified for use in inhomogeneous magnetic fields.