scholarly journals A nuclear magnetic resonance study of water in aggrecan solutions

2016 ◽  
Vol 3 (3) ◽  
pp. 150705 ◽  
Author(s):  
Richard J. Foster ◽  
Robin A. Damion ◽  
Thomas G. Baboolal ◽  
Stephen W. Smye ◽  
Michael E. Ries
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Relaxation Rate ◽  
Activation Energies ◽  
Proton Nuclear Magnetic Resonance ◽  
Water Molecules ◽  
Transverse Relaxation Rate ◽  
Relaxation Rates ◽  
Transverse Relaxation ◽  
Nuclear Magnetic

Aggrecan, a highly charged macromolecule found in articular cartilage, was investigated in aqueous salt solutions with proton nuclear magnetic resonance. The longitudinal and transverse relaxation rates were determined at two different field strengths, 9.4 T and 0.5 T, for a range of temperatures and aggrecan concentrations. The diffusion coefficients of the water molecules were also measured as a function of temperature and aggrecan concentration, using a pulsed field gradient technique at 9.4 T. Assuming an Arrhenius relationship, the activation energies for the various relaxation processes and the translational motion of the water molecules were determined from temperature dependencies as a function of aggrecan concentration in the range 0–5.3% w/w. The longitudinal relaxation rate and inverse diffusion coefficient were approximately equally dependent on concentration and only increased by upto 20% from that of the salt solution. The transverse relaxation rate at high field demonstrated greatest concentration dependence, changing by an order of magnitude across the concentration range examined. We attribute this primarily to chemical exchange. Activation energies appeared to be approximately independent of aggrecan concentration, except for that of the low-field transverse relaxation rate, which decreased with concentration.

scholarly journals In Vivo Quantification of Cerebral R2*-Response to Graded Hyperoxia at 3 Tesla

2015 ◽  
Vol 5 ◽  
pp. 1 ◽  
Author(s):  
Grigorios Gotzamanis ◽  
Roman Kocian ◽  
Pinar S. Özbay ◽  
Manuel Redle ◽  
Spyridon Kollias ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Relaxation Rate ◽  
Tumor Therapy ◽  
Cerebrovascular Reactivity ◽  
Oxygen Intake ◽  
Transverse Relaxation Rate ◽  
Dependent Manner ◽  
Relaxation Rates ◽  
Transverse Relaxation ◽  
Arterial Blood

Objectives: This study aims to quantify the response of the transverse relaxation rate of the magnetic resonance (MR) signal of the cerebral tissue in healthy volunteers to the administration of air with step-wise increasing percentage of oxygen. Materials and Methods: The transverse relaxation rate (R2*) of the MR signal was quantified in seven volunteers under respiratory intake of normobaric gas mixtures containing 21, 50, 75, and 100% oxygen, respectively. End-tidal breath composition, arterial blood saturation (SaO2), and heart pulse rate were monitored during the challenge. R2* maps were computed from multi-echo, gradient-echo magnetic resonance imaging (MRI) data, acquired at 3.0T. The average values in the segmented white matter (WM) and gray matter (GM) were tested by the analysis of variance (ANOVA), with Bonferroni post-hoc correction. The GM R2*-reactivity to hyperoxia was modeled using the Hill's equation. Results: Graded hyperoxia resulted in a progressive and significant (P < 0.05) decrease of the R2* in GM. Under normoxia the GM-R2* was 17.2 ± 1.1 s-1. At 75% O2 supply, the R2* had reached a saturation level, with 16.4 ± 0.7 s-1 (P = 0.02), without a significant further decrease for 100% O2. The R2*-response of GM correlated positively with CO2 partial pressure (R = 0.69 ± 0.19) and negatively with SaO2 (R = -0.74 ± 0.17). The WM showed a similar progressive, but non-significant, decrease in the relaxation rates, with an increase in oxygen intake (P = 0.055). The Hill's model predicted a maximum R2* response of the GM, of 3.5%, with half the maximum at 68% oxygen concentration. Conclusions: The GM-R2* responds to hyperoxia in a concentration-dependent manner, suggesting that monitoring and modeling of the R2*-response may provide new oxygenation biomarkers for tumor therapy or assessment of cerebrovascular reactivity in patients.

Identification of Polychlorinated Pyrenes and Pyrene-Addition Products Using Proton Nuclear Magnetic Resonance Techniques

1987 ◽  
Vol 41 (7) ◽  
pp. 1194-1199 ◽  
Author(s):  
David L. Ashley ◽  
Elizabeth R. Barnhart ◽  
Donald G. Patterson ◽  
Robert H. Hill
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Proton Nuclear Magnetic Resonance ◽  
Relaxation Rates ◽  
Spectral Parameters ◽  
Normal Orientation ◽  
Nmr Techniques ◽  
Nuclear Magnetic

Nuclear magnetic resonance (NMR) techniques are used to determine the chlorination pattern on a number of chlorinated pyrenes and pyrene-addition products. Determining chemical shifts, couplings, and longitudinal relaxation rates makes the unequivocal assignment of these molecules possible. Chlorination under the conditions described here were found to follow the normal orientation rules for pyrene. Spectral parameters obtained from these molecules are consistent enough to allow further application to unknown compounds. This should simplify assigning NMR spectra to other chlorinated pyrene standards.

Nuclear magnetic resonance surface relaxation mechanisms of kerogen

Geophysics ◽  
2017 ◽  
Vol 82 (6) ◽  
pp. JM15-JM22 ◽  
Author(s):  
Boyang Zhang ◽  
Hugh Daigle
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Hydrogen Bonding ◽  
Magnetic Resonance ◽  
Relaxation Rate ◽  
Dipolar Coupling ◽  
Surface Relaxation ◽  
Proton Density ◽  
Transverse Relaxation Rate ◽  
Pore Fluids ◽  
Transverse Relaxation

Nuclear magnetic resonance (NMR) relaxometry is an excellent tool for probing the interactions between solid pore surface and pore fluids in porous media. Surface relaxation is a key component of NMR relaxation. It is well-known that in conventional rocks, paramagnetic centers contribute most to the surface relaxation phenomenon. However, the interactions between organic pore surfaces and pore fluids, and the mechanism of surface relaxation in organic shale pores, are not well-understood. We tackle the issue using deuterated compounds to adjust the proton density in the liquid phase and monitoring the transverse relaxation rate changes of kerogen-fluid mixtures. With the Barnett and Eagle Ford kerogen isolates, we found that for alkanes, it is intramolecular dipolar coupling that dominates among the magnetic interactions. As a result, the transverse relaxation rate of alkane proton spins is more likely to be dependent on the concentration of active adsorption sites on the kerogen surface, rather than the kerogen proton density. For water inside organic pores, surface relaxation most likely originates from hydrogen bonding and intermolecular dipolar coupling. We also examined the temperature effect on kerogen surface relaxation and found temperature-dependent behavior that is consistent with surface relaxation by hydrogen bonding and homonuclear dipolar coupling interactions.

A proton nuclear magnetic resonance relaxation study of the glycine, alanine, and lactate complexes of gadolinium(III) in aqueous solution

1987 ◽  
Vol 65 (7) ◽  
pp. 1508-1512 ◽  
Author(s):  
R. Stephen Reid ◽  
Benjamin Podányi
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Membered Ring ◽  
Proton Nuclear Magnetic Resonance ◽  
Proton Relaxation ◽  
Carboxylate Group ◽  
Relaxation Rates ◽  
Spin Lattice ◽  
Resonance Spin ◽  
Nuclear Magnetic

The 1H nuclear magnetic resonance spin-lattice and spin–spin relaxation rate enhancements induced by the gadolinium(III) ion were measured in solutions of glycine, alanine, and sodium lactate containing different amounts of Gd(III). The proton relaxation rates in the Gd(III) complexes were calculated from these data, and were used to calculate metal–hydrogen atom distances. Comparison of these data with corresponding distances calculated from literature X-ray crystallographic data for model compounds shows that in the two amino acid complexes the Gd(III) ion is coordinated in a four-membered ring through the two oxygen atoms of the carboxylate group. By contrast, in the lactate complex coordination is via a five-membered ring involving one oxygen atom of the carboxylate group and the α-hydroxyl oxygen.

Quantitative Determination of Methemoglobin by Measuring the Solvent-Water Proton-Nuclear Magnetic Resonance Relaxation Rate

1992 ◽  
Vol 38 (12) ◽  
pp. 2401-2404 ◽  
Author(s):  
S Aime ◽  
W Dastrú ◽  
M Fasano ◽  
A Arnelli ◽  
M Castagnola ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Quantitative Determination ◽  
Relaxation Rate ◽  
Proton Nuclear Magnetic Resonance ◽  
Water Proton ◽  
Simple Relationship ◽  
Solvent Water ◽  
Nuclear Magnetic

Abstract We report a new method for the quantitative determination of human methemoglobin (metHb) based on the measurement of the solvent-water proton-nuclear magnetic resonance (NMR) relaxation rate R1 [normalized to 1 mmol/L hemoglobin (Hb) concentration]. MetHb (%) is estimated from the linear dependence of R1 on the metHb concentration, taking into account the simple relationship [MetHb] = [(R1 - R1HbO2)/(R1metHb - R1HbO2)].100, where R1HbO2 and R1metHb are values for the solvent-water relaxation rate of standard 1.0 mmol/L solutions of the oxygenated derivative of human hemoglobin (HbO2) and of metHb, respectively. The minimum metHb that may be determined from the analysis of the experimental data is 0.5 +/- 0.4%.

Zn(II)–D-(−)penicillamine complexes in aqueous solution. Zn-67 nuclear magnetic resonance study

1986 ◽  
Vol 64 (9) ◽  
pp. 1845-1849 ◽  
Author(s):  
Alfred Delville ◽  
Christian Detellier
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nuclear Magnetic Resonance Study ◽  
Transverse Relaxation Rate ◽  
Amino Groups ◽  
Magnetic Resonance Study ◽  
Transverse Relaxation ◽  
Fast Exchange ◽  
Zinc Chelation ◽  
Nuclear Magnetic

D–(−)-Penicillamine interactions with Zn(II) have been studied in aqueous solutions as a function of pH, penicillamine concentration, and temperature, using Zn-67 nuclear magnetic resonance. Longitudinal and transverse relaxation rate measurements show the presence in solution of complexes in fast exchange with the aquated Zn(II) cation, and belonging to the extreme narrowing regime. Using equilibrium constant values from the literature, the relaxation behaviour was modelled. Characteristic Zn-67 line width values for the two complexes Zn(Pen) (v = (6200 ± 500) Hz) and [Zn(Pen H)]+ (v = (6000 ± 1000) Hz) were found. Equality of the two values is in agreement with zinc chelation by the sulfhydryl and the amino groups.

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