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Jia Mao Anayancy Osorio-Madrazo Marie-Pierre Laborie 《Cellulose (London, England)》2013,20(4):1829-1840
Cellulose I nanowhiskers were prepared in relatively high yield (48 ± 2 %) by single-stage hydrolysis of microcrystalline cellulose with an aqueous solution of 1-butyl-3-methylimidazolium hydrogen sulfate ([Bmim]HSO4). This reaction occurred under mildly acidic reaction conditions with an [H+]/[AGU] ratio of 0.24 mol/mol, i.e., 2 orders of magnitude lower than with concentrated sulfuric acid. The nanowhiskers exhibited small width and width distribution and also smaller length than nanowhiskers obtained with concentrated acid. With a relatively low content of sulfur they also exhibited higher thermal stability than whiskers obtained with concentrated sulfuric acid. The lower solvating power of the aqueous ionic liquid compared to that of concentrated sulfuric acid likely contributes to the greater hydrolysis efficiency in the present system. 相似文献
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Substitution pattern elucidation of hydroxypropyl Pinus pinaster (Ait.) bark polyflavonoid derivatives by ESI(−)‐MS/MS
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Danny E. García Marrero Wolfgang G. Glasser Antonio Pizzi Sebastian Paczkowski Marie‐Pierre G. Laborie 《Journal of mass spectrometry : JMS》2014,49(10):1050-1058
The structure of condensed tannins (CTs) from Pinus pinaster bark extract and their hydroxypropylated derivatives with four degrees of substitution (DS 1, 2, 3 and 4) has been characterized for the first time using negative‐ion mode electrospray ionization tandem mass spectrometry (ESI(?)‐MS/MS). The results showed that P. pinaster bark CTs possess structural homogeneity in terms of monomeric units (C15, catechin). The oligomer sizes were detected to be dimers to heptamers. The derivatives showed typical phenyl‐propyl ether mass fragmentation by substituent elimination (58 amu) and inherent C15 flavonoid fissions. The relative abundance of the product ions revealed a preferential triple, tetra‐/penta‐ and octa‐ hydroxypropylation substitution pattern in the monomer, dimer and trimer derivatives, respectively. A defined order of –OH reactivity towards propylene oxide was established by means of multistage experiments (A‐ring ≥ B‐ring > C‐ring). A high structural heterogeneity of the modified oligomers was detected. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Conservative methods for the Toda lattice equations 总被引:1,自引:0,他引:1
We are concerned with the numerical integration of the Todalattice equations by using different conservative methods. Numericalexperiments suggest that the global error for isospectral schemesdecreases exponentially with time but it is almost constantfor either symplectic or more general integrators. We providea theoretical explanation for these experimental findings. 相似文献
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X. Ledoux J. Sigaud T. Granier J-P. Lochard Y. Patin P. Pras C. Varignon J-M. Laborie Y. Boulin F. Gunsing 《The European Physical Journal A - Hadrons and Nuclei》2006,27(1):59-65
The creation of isomeric nuclei by neutron capture in the resonances energy range was studied with the lead slowing-down assembly
CIRENE. The isomeric-ratio measurement of 8 nuclei allows to determine the spin of the compound nucleus at the binding energy.
An experiment on 177Lu underlines the role of the spin of a resonance on the isomeric-state feeding probability. 相似文献
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