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Viral diseases affect grapevine cultures without inducing any resistance response. Thus, these plants develop systemic diseases and are chronically infected. Molecular events associated with viral compatible infections responsible for disease establishment and symptoms development are poorly understood. In this study, we surveyed viral infection in(More)
The proton chemical shift (CS) tensor is a sensitive probe of structure and hydrogen bonding. Highly accurate quantum-chemical protocols exist for computation of (1)H magnetic shieldings in the various contexts, making proton chemical shifts potentially a powerful predictor of structural and electronic properties. However, (1)H CS tensors are not yet widely(More)
The effects of pulse imperfections and RF inhomogeneity on NMR spectra obtained with phase-modulated multiple-pulse NMR sequences are analyzed. The emphasis is on the combined effects of frequency offset, RF inhomogeneity, and pulse phase transients. To enable a theoretical description of the transients associated with phase changes under continuous RF(More)
Retroviruses selectively package two copies of their unspliced genomes by what appears to be a dimerization-dependent RNA packaging mechanism. Dimerization of human immunodeficiency virus Type-1 (HIV-1) genomes is initiated by “kissing” interactions between GC-rich palindromic loop residues of a conserved hairpin (DIS), and is indirectly promoted by(More)
A universal function is proposed to describe REAPDOR dephasing curves of an observed spin-1/2 nucleus dipole-recoupled to a spin-1 quadrupolar nucleus ((2)H or (14)N). Previous work had shown that, in contrast to REDOR, the shape of the dephasing curve depends on a large number of parameters including the quadrupolar coupling constant and asymmetry(More)
A method for acquiring triple quantum filtered (TQF) (23)Na NMR images is proposed that takes advantage of the differences in transverse relaxation rates of sodium to achieve positive intensity, PI, NMR signal. This PITQF imaging sequence has been used to obtain spatially resolved one-dimensional images as a function of the TQF creation time, tau, for two(More)
A universal curve for the solid-state NMR REAPDOR experiment on an isolated spin-1/2-spin-5/2 pair is proposed that provides a simple means to measure their interatomic distance. REAPDOR data were obtained at three separate REAPDOR experiments using different values of the rotor spinning frequency. All points were fitted simultaneously to the universal(More)
We report a Phase-Alternating R-Symmetry (PARS) dipolar recoupling scheme for accurate measurement of heteronuclear (1)H-X (X = (13)C, (15)N, (31)P, etc.) dipolar couplings in MAS NMR experiments. It is an improvement of conventional C- and R-symmetry type DIPSHIFT experiments where, in addition to the dipolar interaction, the (1)H CSA interaction persists(More)
  • A. J. Vega
  • Solid state nuclear magnetic resonance
  • 1992
The spin dynamics of Hartmann-Hahn cross-polarization from I = 1/2 to quadrupolar S = 3/2 nuclei is investigated. A density-matrix model applicable to cases where the quadrupole frequency vQ is much larger than the rf amplitude v1S of the S spins, predicts the time development of the spin state of an isolated I, S spin pair in static situations and in three(More)