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.

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.

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.

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.

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