Nuclear Magnetic Resonance and Quadrupole Coupling in Hydrous and Anhydrous Sodium Molybdate and Sodium Tungstate Spinel

1972 ◽  
Vol 50 (6) ◽  
pp. 567-572 ◽  
Author(s):  
G. F. Lynch ◽  
S. L. Segel
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Sodium Tungstate ◽  
Sodium Molybdate ◽  
Tone Burst ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Order Effects ◽  
Nuclear Magnetic

The nuclear magnetic resonance of 23Na in powder samples of hydrous and anhydrous sodium molybdate and sodium tungstate has been investigated. The anhydrous compounds crystallize in the cubic spinel of type H11, Fd3m presumably with ionic charges of 1 + and 6 + on the metals. The 23Na quadrupole couplings are the largest yet observed for this nucleus and have values of 2.62 and 2.48 MHz in the molybdate and tungstate respectively, as determined from both first- and second-order effects on the magnetic resonance spectrum. These couplings have negligible temperature dependences. Using charges of 1 + and 6 + for the metal ions, assuming that the oxygens are in their ideal positions in the spinel structure and neglecting any contributions from oxygen dipoles and quadrupoles, the electric field gradient was calculated to be 12 × 1013 e.s.u./cm3, in good agreement with the experimental gradient of 7.5 × 1013 e.s.u./cm3. Preliminary measurements of the sodium spin–lattice relaxation time, using tone-burst techniques, indicated a value between 30–60 s. The 95.97Mo nuclear resonances were also observed in the molybdate and these resonances showed no quadrupole effects.

Nuclear Magnetic Resonance Brain Imaging in Chronic Schizophrenia

1987 ◽  
Vol 150 (2) ◽  
pp. 161-163 ◽  
Author(s):  
J. A. O. Besson ◽  
F. M. Corrigan ◽  
G. R. Cherryman ◽  
F. W. Smith
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Lattice Relaxation ◽  
Chronic Schizophrenia ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Magnetic Resonance Brain Imaging ◽  
Normal Controls ◽  
Nuclear Magnetic

Patients with chronic schizophrenia were examined by nuclear magnetic resonance imaging of the brain. Subgroups of the syndrome with high positive or high negative symptom scores and ventricular dilatation were compared with each other and with normal controls in respect of regional spin lattice relaxation time (T1) changes. Significant differences were not observed between the schizophrenic subgroups and controls but there were significant differences between the subgroups themselves. The presence of tardive dyskinesia was associated with increased T1 of the basal ganglia. The significance of these results is discussed in relation to findings using other techniques.

Solute 13C Nuclear Magnetic Resonance Spectrometric Investigation of Acetonitrile-Tetraalkylammonium Salt Interactions

1983 ◽  
Vol 37 (1) ◽  
pp. 29-31
Author(s):  
Neal R. Dando ◽  
Harvey S. Gold ◽  
Cecil Dybowski
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Salt Concentration ◽  
Alkyl Chain ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
13C Nuclear Magnetic Resonance ◽  
Nuclear Magnetic

Carbon-13 nuclear magnetic resonance spectrometry is used to observe changes in the spin-lattice relaxation time ( T1) of the alkyl chain carbons of symmetric tetraalkylammonium salts ( R4N+) X− in acetonitrile as a function of salt concentration in the range from 0.25 to 1.4 M. The T1 values of the alkyl chain carbons are observed to be differentially sensitive to salt concentration, the sensitivity being greatest at the α carbon position. These observations suggest accessibility of the cation nitrogen to solvent molecules and changing microviscosity about the salt molecule.

scholarly journals 158 Dormancy of Ornithogalum Evaluated by Nuclear Magnetic Resonance Imaging

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 417B-417
Author(s):  
M.S. Roh ◽  
M. Line ◽  
Y.H. Joung ◽  
P. Brannigan
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Cross Section ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Inflorescence Development ◽  
Leaf Emergence ◽  
The Cross ◽  
Nuclear Magnetic

Ornithogalum hybrid bulbs (selection 327-2) were stored dry at 10, 16, 22, 28, and 35 °C for 6 weeks upon harvest. After storage, bulbs were subjected to a nuclear magnetic resonance (NMR) imaging to obtain the longitudinal spin-lattice relaxation time (T1) profile across the cross section of intact bulbs and to a scanning electron microscopy (SEM) to observe an inflorescence development. Bulbs were forced in a greenhouse maintained at 21/19 °C. When bulbs were stored at 10, T1 was shorter through the cross section of bulbs and the shoot apex was under a vegetative stage. This suggests that dormancy was not broken during the storage, leaf emergence was delayed, and plants failed to flower. Bulbs stored at 22 and 28 °C formed the primary scape and inflorescence with several florets. At the base of the primary scape of bulbs stored at 22 °C, a vegetative apex was observed by both MR imaging (MRI) and SEM. In the center of bulbs where leaves and floral organs were present, T1 was longer as compared to the scales. This suggests that dormancy in the scales was broken and the leaves and scape were ready to emerge. Leaf emergence and flowering was the fastest when bulbs were stored at 22 °C and at 16 or 22 °C, respectively. Due to its nondestructive nature, MRI can be used to study the state of bulb dormancy and also the progress of inflorescence development during bulb storage prior to planting.

Na(+)-K(+)-ATPase in endothelial cell energetics: 23Na nuclear magnetic resonance and calorimetry study

1995 ◽  
Vol 268 (1) ◽  
pp. H351-H358 ◽  
Author(s):  
M. L. Gruwel ◽  
C. Alves ◽  
J. Schrader
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Vascular Endothelial Cells ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Shift Reagent ◽  
Spin Lattice Relaxation ◽  
Resonance Spectroscopy ◽  
Spin Lattice ◽  
Nuclear Magnetic

Sodium flux rate and energy consumption of the Na(+)-K+ pump in vascular endothelial cells of porcine aorta grown on micro-carrier beads were studied using a combination of nuclear magnetic resonance spectroscopy of intracellular 23Na and microcalorimetry. The Na+ flux into the cells was determined in the presence of the shift reagent Dy(P3O10)2(7-), while the Na(+)-K+ pump was inhibited with ouabain. Basal Na+ influx was 17 +/- 3 nmol.min-1.mg protein-1, and intracellular Na+ concentration was 23.5 +/- 3.8 mM, resulting in a complete exchange of intracellular Na+ within 5–6 min. Spin-lattice relaxation time (T1) measurements of intracellular Na+ showed a T1 of 19 +/- 1 ms under basal conditions and a T1 of 26.2 +/- 1.6 ms after pump inhibition with 50 microM ouabain. Such an increase is typical for a system in which the total amount of Na+ increases but where the amount of bound Na+ remains constant. The Na+ ionophore nystatin maximally increased the Na(+)-K+ pump rate about twofold, whereas the amount of intracellular Na+ only increased 14%. With microcalorimetry a cellular heat flux of 183 +/- 18 microW per mg endothelial protein was determined, which relates to 7.6 microW/mg endothelial protein generated by the Na(+)-K(+)-adenosinetriphosphatase. Our data demonstrate that small intracellular changes of Na+ can stimulate the endothelial Na(+)-K+ pump activity. The contribution of the Na(+)-K+ pump to total endothelial energy expenditure is approximately 4-5%.

Nuclear Magnetic Resonance Study of the Interaction of SBR with Carbon Black

1969 ◽  
Vol 42 (4) ◽  
pp. 1155-1166 ◽  
Author(s):  
M. A. Waldrop ◽  
G. Kraus
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Carbon Black ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Nuclear Magnetic Resonance Study ◽  
Spin Lattice Relaxation ◽  
Segmental Motion ◽  
Spin Lattice ◽  
Nuclear Magnetic

Abstract The nuclear magnetic resonance relaxation characteristics of an amorphous styrene—butadiene copolymer (SBR-1500) containing HAF and ISAF carbon black and an HAF carbon black containing SBR-1500 adsorbed on it from solution have been investigated at 30 Mc/sec over a temperature range of −100° to 100° C. The spin-lattice relaxation time (T1) passes through a single, broad minimum at about 30° C. The precise location of this minimum which is ascribed to the onset of segmental motion in the copolymer is not strongly dependent on the presence of carbon black. The nuclear magnetic resonance results reported suggest that the spectrum of correlation times of the elastomer strongly associated with the carbon black particles, i.e., the “bound rubber” is not significantly different from that of the bulk elastomer containing no carbon black—at least for the frequencies sampled by the NMR technique used. The results thus fail to confirm recent proposals in the literature suggesting that filler particles in elastomers are covered with a layer of polymer in which segmental motion is severely restricted and which constitutes a significant, if not the major portion of the rubber.

Nuclear Magnetic Resonance Investigation of Possible Molecular Motion in Coronene, Perlene, and Triphenlene in the Solid State

1971 ◽  
Vol 49 (20) ◽  
pp. 3332-3335 ◽  
Author(s):  
C. A. Fyfe ◽  
B. A. Dunell ◽  
J. Rimeester
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Molecular Structures ◽  
Spin Lattice Relaxation ◽  
Molecular Reorientation ◽  
Spin Lattice ◽  
Magnetic Resonance Investigation ◽  
Nuclear Magnetic

Broad-line nuclear magnetic resonance (n.m.r.) and spin lattice relaxation time measurements on solid coronene indicate the presence of a molecular reorientation process at 160 °K. The activation energy for the process has been determined at 5.9 kcal/mol and the nature of the motion deduced as being reorientation in the plane of the molecule. No motional processes are observed for perylene or triphenylene.The results are discussed with respect to thermodynamic data and the molecular structures.

Pulsed nuclear magnetic resonance in a tin single crystal

1968 ◽  
Vol 46 (7) ◽  
pp. 871-877 ◽  
Author(s):  
L. A. McLachlan
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Single Crystal ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Average Value ◽  
Spin Lattice ◽  
Pulsed Nuclear Magnetic Resonance ◽  
Nuclear Magnetic

Pulsed nuclear magnetic resonance studies of an isotopically pure 119Sn single crystal were made at 78 °K. An attempt to observe anisotropy in the spin–lattice relaxation time was inconclusive, but gave T1T = (34 ± 2) ms deg as the average value. Spin–spin relaxation was dominated by the pseudo-exchange interaction. The numerical value for this, (2.0 ± 0.5) kc/s, is in agreement with the value calculated from the Rudermann–Kittel theory. A strong pseudodipolar interaction was also observed.

Nuclear Magnetic Resonance Studies of δ-Stabilized Plutonium

2003 ◽  
Vol 802 ◽  
Author(s):  
N. J. Curro ◽  
L. Morales
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Low Frequency ◽  
Lattice Relaxation ◽  
Spin Fluctuations ◽  
Spin Lattice Relaxation ◽  
Cubic Symmetry ◽  
Magnetic Resonance Studies ◽  
Local Distortions ◽  
Nuclear Magnetic

Nuclear Magnetic Resonance studies of Ga stabilized δ-Pu reveal detailed information about the local distortions surrounding the Ga impurities as well as provides information about the local spin fluctuations experienced by the Ga nuclei. The Ga NMR spectrum is inhomogeneously broadened by a distribution of local electric field gradients (EFGs), which indicates that the Ga experiences local distortions from cubic symmetry. The Knight shift and spin lattice relaxation rate indicate that the Ga is dominantly coupled to the Fermi surface via core polarization, and is inconsistent with magnetic order or low frequency spin correlations.

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