scholarly journals TRANSFORMADA INVERSA DE LAPLACE PARA ANÁLISE DE SINAIS DE RESSONÂNCIA MAGNÉTICA NUCLEAR DE BAIXO CAMPO

Química Nova ◽  
2021 ◽  
Author(s):  
Tiago Moraes
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Laplace Transform ◽  
Tikhonov Regularization ◽  
Signal Analysis ◽  
Singular Values ◽  
Inverse Laplace Transform ◽  
Mathematical Procedure ◽  
Low Field ◽  
Nuclear Magnetic

INVERSE LAPLACE TRANSFORM FOR SIGNAL ANALYSIS OF LOW FIELD NUCLEAR MAGNETIC RESONANCE. The objective of this work is to describe the mathematical procedure denominated ‘Inverse Laplace Transform’ used to process Low Field Nuclear Magnetic Resonance signals of experiments as CPMG, Inversion Recovery and Saturation Recovery. Also, we present a developed script, “ILT Origin script” v.1, in the environment of the software Origin Lab 9 to execute it. The presented ILT is executed with an algorithm of non-negative last square, with Tikhonov regularization and singular values decomposition. The main features of the code were tested using simulated and experimental signals, and in order to validate the results the same sets of data were analyzed using similar ILT softwares. The developed scripts for Origin Lab, Matlab and other languages are available for free for scientific and teaching uses.

Configuration of the ring nitrogen in N-oxides and the conformation of tropanes. Part XVIII

1968 ◽  
Vol 46 (17) ◽  
pp. 2761-2766 ◽  
Author(s):  
Nagabhushanam Mandava ◽  
Gabor Fodor
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Signal Analysis ◽  
Chair Conformation ◽  
Coupling Constants ◽  
Amine Oxides ◽  
Low Field ◽  
Ring Nitrogen ◽  
Nuclear Magnetic

The configurations of ring nitrogen in the amine oxides of tropine, oscine, atropine, and scopolamine have been investigated by nuclear magnetic resonance (n.m.r.) spectroscopy. Oxygen function(s) at C-6β (and 7β) were found to deshield the low-field, equatorial N-methyl signal. Analysis of the n.m.r. spectra of epoxides of some tropane bases, in particular the coupling constants, clearly indicates preponderance of the (slightly distorted) chair conformation even in the tropanes with a bulky group in the 3α (endo) position. The protons on the epoxide carbons are magnetically non-equivalent in scopolamine (5b) and its N-oxide while appearing as a singlet in the alkamine, i.e. scopine (5a).

Application of Low-Field Nuclear Magnetic Resonance (LFNMR) in Characterizing the Dissociation of Gas Hydrate in a Porous Media

2021 ◽  
Vol 35 (3) ◽  
pp. 2174-2182
Author(s):  
Yongchao Zhang ◽  
Lele Liu ◽  
Daigang Wang ◽  
Pengfei Chen ◽  
Zhun Zhang ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Porous Media ◽  
Magnetic Resonance ◽  
Gas Hydrate ◽  
Low Field ◽  
Nuclear Magnetic

scholarly journals A New Hybrid Inversion Method for 2D Nuclear Magnetic Resonance Combining TSVD and Tikhonov Regularization

2021 ◽  
Vol 7 (2) ◽  
pp. 18
Author(s):  
Germana Landi ◽  
Fabiana Zama ◽  
Villiam Bortolotti
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Tikhonov Regularization ◽  
Large Scale ◽  
Regularization Parameter ◽  
High Sensitivity ◽  
Inversion Method ◽  
Nmr Relaxometry ◽  
Value Decomposition ◽  
Nuclear Magnetic

This paper is concerned with the reconstruction of relaxation time distributions in Nuclear Magnetic Resonance (NMR) relaxometry. This is a large-scale and ill-posed inverse problem with many potential applications in biology, medicine, chemistry, and other disciplines. However, the large amount of data and the consequently long inversion times, together with the high sensitivity of the solution to the value of the regularization parameter, still represent a major issue in the applicability of the NMR relaxometry. We present a method for two-dimensional data inversion (2DNMR) which combines Truncated Singular Value Decomposition and Tikhonov regularization in order to accelerate the inversion time and to reduce the sensitivity to the value of the regularization parameter. The Discrete Picard condition is used to jointly select the SVD truncation and Tikhonov regularization parameters. We evaluate the performance of the proposed method on both simulated and real NMR measurements.

Sign in / Sign up

Export Citation Format

Share Document