Study of specific interaction between nucleotides and dye support by nuclear magnetic resonance

2011 ◽  
Vol 24 (6) ◽  
pp. 975-980 ◽  
Author(s):  
Carla Cruz ◽  
Renato E. F. Boto ◽  
Paulo Almeida ◽  
João A. Queiroz
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Specific Interaction ◽  
Nuclear Magnetic

The effect of tetra-n-butylammonium salts on the nuclear magnetic resonance of nitrobenzene

1968 ◽  
Vol 46 (1) ◽  
pp. 74-74 ◽  
Author(s):  
J. B. Hyne ◽  
A. R. Fabris
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Aromatic Ring ◽  
Specific Interaction ◽  
Ion Pair ◽  
Carbon Tetra ◽  
Resonance Response ◽  
Nuclear Magnetic Resonance Response ◽  
Nuclear Magnetic

Tetra-n-butylammonium salts effect the nuclear magnetic resonance response of the para and meta protons of nitrobenzene to a greater extent than that of the ortho protons in solutions in carbon tetra chloride. It is suggested that this effect may be due to a specific interaction between the salt, in ion-pair form, and the aromatic ring of nitrobenzene.

A 13C and 15N nuclear magnetic resonance study of the protonation of a retinal Schiff base by acids of different pKas and in solvents of different polarities

1987 ◽  
Vol 65 (7) ◽  
pp. 1576-1583 ◽  
Author(s):  
Daniel Cossette ◽  
Daniel Vocelle
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Schiff Base ◽  
Magnetic Resonance ◽  
Specific Interaction ◽  
Nuclear Magnetic Resonance Study ◽  
Polar Groups ◽  
Nuclear Magnetic Resonance Spectra ◽  
Mineral Acids ◽  
Tert Butylamine ◽  
Nuclear Magnetic

13C and 15N nuclear magnetic resonance spectra of mixtures of all-trans-retinylidene tert-butylamine (RtBA) and substituted acetic acids in equimolar concentrations in both CDCl3 and CD3OD were studied in relation to two questions: the nature of the state of protonation of a retinal Schiff base in the presence of carboxylic and mineral acids in solvents of different polarities, and secondly, to determine the nature of the interactions (if any) between the polar groups located on the acids and the polyenic chain of the retinal derivative. Using carboxylic acids of different pKas and three mineral acids, we present results that indicate that, in solvents of low polarity, weak acids can only partially protonate RtBA while, in a more polar milieu, the protonation percentages are higher. With polar groups such asNO2, Cl, Br, I, and CN, no specific interaction could be found between the polyenic chain of the imine and these groups. Variations in the intensity of certain peaks of RtBA were noted and these could possibly be related to the presence of the polar groups on the acids. Comparisons of our results with those obtained on rhodopsin and bacteriorhodopsin indicate that the milieu surrounding the chromophore must be polar if protonation is complete, while in a less polar environment partial protonation can be expected.

An emerging technology: Nuclear magnetic resonance microscopy

1988 ◽  
Vol 46 ◽  
pp. 1000-1001
Author(s):  
M.J. Hennessy ◽  
E. Kwok
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Relaxation Times ◽  
Basic Research ◽  
Local Environment ◽  
Magnetic Resonance Images ◽  
Nmr Microscopy ◽  
Mri Scans ◽  
Temperature Relaxation ◽  
Nuclear Magnetic

Much progress in nuclear magnetic resonance microscope has been made in the last few years as a result of improved instrumentation and techniques being made available through basic research in magnetic resonance imaging (MRI) technologies for medicine. Nuclear magnetic resonance (NMR) was first observed in the hydrogen nucleus in water by Bloch, Purcell and Pound over 40 years ago. Today, in medicine, virtually all commercial MRI scans are made of water bound in tissue. This is also true for NMR microscopy, which has focussed mainly on biological applications. The reason water is the favored molecule for NMR is because water is,the most abundant molecule in biology. It is also the most NMR sensitive having the largest nuclear magnetic moment and having reasonable room temperature relaxation times (from 10 ms to 3 sec). The contrast seen in magnetic resonance images is due mostly to distribution of water relaxation times in sample which are extremely sensitive to the local environment.

Nuclear magnetic resonance microscopy

1989 ◽  
Vol 47 ◽  
pp. 828-829
Author(s):  
Paul C. Lauterbur
Keyword(s):  
Magnetic Field ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Fields ◽  
Signal To Noise ◽  
Field Gradients ◽  
Useful Signal ◽  
Magnetic Field Gradients ◽  
Observation Times ◽  
Nuclear Magnetic

Nuclear magnetic resonance imaging can reach microscopic resolution, as was noted many years ago, but the first serious attempt to explore the limits of the possibilities was made by Hedges. Resolution is ultimately limited under most circumstances by the signal-to-noise ratio, which is greater for small radio receiver coils, high magnetic fields and long observation times. The strongest signals in biological applications are obtained from water protons; for the usual magnetic fields used in NMR experiments (2-14 tesla), receiver coils of one to several millimeters in diameter, and observation times of a number of minutes, the volume resolution will be limited to a few hundred or thousand cubic micrometers. The proportions of voxels may be freely chosen within wide limits by varying the details of the imaging procedure. For isotropic resolution, therefore, objects of the order of (10μm) may be distinguished.Because the spatial coordinates are encoded by magnetic field gradients, the NMR resonance frequency differences, which determine the potential spatial resolution, may be made very large. As noted above, however, the corresponding volumes may become too small to give useful signal-to-noise ratios. In the presence of magnetic field gradients there will also be a loss of signal strength and resolution because molecular diffusion causes the coherence of the NMR signal to decay more rapidly than it otherwise would. This phenomenon is especially important in microscopic imaging.

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