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18-02-2017
The chemical bonding in actinide compounds is usually analysed by inspecting the shape and the occupation of the orbitals or by calculating bond orders which are based on orbital overlap and occupation numbers. However, this may not give a definite answer because the choice of the partitioning method may strongly influence the result possibly leading to qualitatively different answers.
17-02-2017
Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful tool for biology, allowing structural and chemical analysis of metabolites as well as imagery (MRI). A collaboration of scientists from Nimbe, Neurospin and Bordeaux University, has recently designed a non-invasive online NMR μ-probe for profiling in-vivo metabolic physiological activities with a micro-size NMR detector placed in "close proximity" to a microdialysis sampling probe.
30-12-2016
La résonance magnétique nucléaire (RMN) est une technique d'analyse puissante mais peu sensible. Des enjeux majeurs en analyse chimique (détection de produits en très faibles concentrations ou étude des effets isotopiques, notamment) incitent à rechercher de nouvelles méthodes pour détecter et séparer les signaux faibles des composantes principales du signal.
31-03-2009
H. Desvaux, D. J.Y. Marion, G. Huber, P. Berthault
In nuclear magnetic resonance (NMR) whose medical application is known as MRI, it is the voltage at the extremities of a coil that is usually monitored, since it reflects the variation of the induction created by the precession of the nuclear magnetization after a radiofrequency (RF) excitation pulse. The nuclear magnetization results from the difference in population between the spin states, induced by the strong static magnetic field.
30-07-2008
Authors: D.J. Marion, G. Huber, P. Berthault, H. Desvaux
Liquid-state NMR is a very powerful method for chemical analysis but it suffers from inherent low sensitivity due to the weak involved energies, which leads to small thermal equilibrium polarization. A solution consists in resorting to transiently polarized nuclear spin systems such as those prepared by optical pumping or dynamic nuclear polarization. Nevertheless, the direct extension of the whole liquid-state NMR techniques to these systems might be less straightforward than anticipated.

 

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