Two-dimensional heteronuclear 1H ↔ 27Al-correlated MAS NMR spectra of layered silicates

2001 ◽  
pp. 249-250 ◽  
Author(s):  
María D. Alba ◽  
Ana I. Becerro ◽  
Miguel A. Castro ◽  
Ana C. Perdigón
1999 ◽  
Vol 139 (2) ◽  
pp. 314-333 ◽  
Author(s):  
J.H. Kristensen ◽  
H. Bildsøe ◽  
H.J. Jakobsen ◽  
N.C. Nielsen
Keyword(s):  
Mas Nmr ◽  

1992 ◽  
Vol 97 (2) ◽  
pp. 435-443 ◽  
Author(s):  
Stefan Féaux De Lacroix ◽  
Jeremy J Titman ◽  
Alfred Hagemeyer ◽  
Hans W Spiess
Keyword(s):  
Mas Nmr ◽  

1987 ◽  
Vol 52 (10) ◽  
pp. 2460-2473 ◽  
Author(s):  
Jan Schraml ◽  
Eva Petráková ◽  
Ján Hirsch ◽  
Jan Čermák ◽  
Václav Chvalovský ◽  
...  

Anomer structures of crystalline D-xylopyranose, all positional isomers of β-D-xylopyranosyl-D-xylopyranose and 2,4-di-β-D-xylopyranosyl-D-xylopyranose were determined by 13C MAS NMR spectroscopy. The saccharides were pertrimethylsilylated by different methods yielding different ratios of pertrimethylsilylated anomers. The NMR spectra (1H, 13C, and 29Si) were assigned by two-dimensional chemical shift correlations. In the anomeric mixtures complete overlap in parts of proton spectra is frequent. In such a case, samples with different anomer ratios considerably facilitate assignment of both 13C and 29Si NMR lines. In analytical applications, however, that method of trimethylsilylation must be chosen which does not allow anomerization prior to silylation. 29Si NMR spectra furnish correct number of OH groups present in the parent compound prior to silylation. Assigned silicon chemical shifts can be used for determination of the sites of glycosidation in oligosaccharides. Glycosidic carbon atoms are considerably shielded after pertrimethylsilylation.


2014 ◽  
Vol 59 (2) ◽  
pp. 57-73 ◽  
Author(s):  
Christopher L. Suiter ◽  
Sivakumar Paramasivam ◽  
Guangjin Hou ◽  
Shangjin Sun ◽  
David Rice ◽  
...  

1984 ◽  
Vol 17 (3) ◽  
pp. 501-502 ◽  
Author(s):  
C. A. Fyfe ◽  
P. J. Stephenson ◽  
M. G. Taylor ◽  
T. L. Bluhm ◽  
Y. Deslandes ◽  
...  
Keyword(s):  
Mas Nmr ◽  

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Agnieszka Skorupa ◽  
Mateusz Ciszek ◽  
Ewa Chmielik ◽  
Łukasz Boguszewicz ◽  
Małgorzata Oczko-Wojciechowska ◽  
...  

AbstractThe purpose of this work was to investigate the distinct and common metabolic features of the malignant and benign thyroid lesions in reference to the non-transformed tissue from the contralateral gland (chronic thyroiditis and colloid goiter). 1H HR MAS NMR spectra of 38 malignant lesions, 32 benign lesions and 112 samples from the non-tumoral tissue (32 from chronic thyroiditis and 80 samples from colloid goiter) were subjected both to multivariate and univariate analysis. The increased succinate, glutamine, glutathione, serine/cysteine, ascorbate, lactate, taurine, threonine, glycine, phosphocholine/glycerophosphocholine and decreased lipids were found in both lesion types in comparison to either colloid goiter or chronic thyroiditis. The elevated glutamate and choline, and reduced citrate and glucose were additionally evident in these lesions in reference to goiter, while the increased myo-inositol—in comparison to thyroiditis. The malignant lesions were characterized by the higher alanine and lysine levels than colloid goiter and thyroiditis, while scyllo-inositol was uniquely increased in the benign lesions (not in cancer) in comparison to both non-tumoral tissue types. Moreover, the benign lesions presented with the unique increase of choline in reference to thyroiditis (not observed in the cancerous tissue). The metabolic heterogeneity of the non-tumoral tissue should be considered in the analysis of metabolic reprogramming in the thyroid lesions.


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