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521.
Dr. Victor Gonzalez Ida Fazlic Dr. Marine Cotte Dr. Frederik Vanmeert Arthur Gestels Steven De Meyer Fréderique Broers Dr. Joen Hermans Dr. Annelies van Loon Prof. Koen Janssens Petria Noble Prof. Katrien Keune 《Angewandte Chemie (International ed. in English)》2023,62(16):e202216478
The Night Watch, painted in 1642 and on view in the Rijksmuseum in Amsterdam, is considered Rembrandt's most famous work. X-ray powder diffraction (XRPD) mapping at multiple length scales revealed the unusual presence of lead(II) formate, Pb(HCOO)2, in several areas of the painting. Until now, this compound was never reported in historical oil paints. In order to get insights into this phenomenon, one possible chemical pathway was explored thanks to the preparation and micro-analysis of model oil paint media prepared by heating linseed oil and lead(II) oxide (PbO) drier as described in 17th century recipes. Synchrotron radiation based micro-XRPD (SR-μ-XRPD) and infrared microscopy were combined to identify and map at the micro-scale various neo-formed lead-based compounds in these model samples. Both lead(II) formate and lead(II) formate hydroxide Pb(HCOO)(OH) were detected and mapped, providing new clues regarding the reactivity of lead driers in oil matrices in historical paintings. 相似文献
522.
Marion Girard Annika Lehtimki Giuseppe Bee Frigga Dohme-Meier Maarit Karonen Juha-Pekka Salminen 《Molecules (Basel, Switzerland)》2020,25(24)
Proanthocyanidins are plant specialized metabolites which are beneficial to animal nutrition and health. This study determined how proanthocyanidin profiles of sainfoin (Onobrychis viciifolia) and birdsfoot trefoil (Lotus corniculatus) change during the forage conservation process and along the digestive tract of lamb. We determined soluble, protein- and fiber-bound proanthocyanidins by spectrophotometric methods and soluble proanthocyanidin profiles by UPLC-MS/MS. During the conservation process, the total proanthocyanidin contents reduced in both forages and the relative proportion of insoluble proanthocyanidins increased, especially in sainfoin. The soluble proanthocyanidins, their mean degree of polymerization and the relative prodelphinidin share declined in both feed species. In the abomasum of lambs fed sainfoin silage, most of the proanthocyanidins were in insoluble form bound to proteins and fibers, but in the small and large intestines, the proportion of soluble proanthocyanidins increased again. For lambs fed birdsfoot trefoil, the trend was not so clear as proanthocyanidins were already mainly soluble in the abomasum. Nevertheless, a large part of soluble proanthocyanidins was recovered in the digestive tract but could not be detected by the UPLC-MS/MS method used. This study suggests that proanthocyanidins have probably been metabolized in the digestive tract by the resident microbiota. 相似文献
523.
L. Patrone D. Nelson V.I. Safarov S. Giorgio M. Sentis W. Marine 《Applied Physics A: Materials Science & Processing》1999,69(7):S217-S221
We show that conventional pulsed laser ablation (PLA) of Si and Ge targets in inert buffer gases is an efficient method of nanocluster synthesis. From a photoluminescence study of Si and Ge nanoclusters produced by PLA we have demonstrated the possibility of tuning the luminescence band from the near infrared to the near ultraviolet regions. The stabilization of the properties of Si nanoclusters by reactive (H2 gas) PLA synthesis was proved by photoluminescence measurements. Finally, we report a photoluminescence study of gas-suspended Ge nanoclusters during their preparation. They exhibit a broad luminescence spectrum extended from UV to the blue-green region and modulated by a molecule-like structure. We propose an interpretation of the vibronic structure involving Ge-O-Ge vibrations at the surface of photo-excited clusters. To the best of our knowledge, we report here the first observation of vibrational effects from gas-suspended Ge nanoclusters. 相似文献
524.
Xiaoli Liang Mani K. Sen Jo‐Ann Jee Oleg Gelman Jeannette E. Marine Kenneth Kan Maya K. Endoh Deborah A. Barkley Tadanori Koga Jonathan G. Rudick 《Journal of polymer science. Part A, Polymer chemistry》2014,52(22):3221-3239
Attaching dendritically branched side chains to each repeat unit of a linear polymer produces molecular building blocks of nanometer‐sized dimensions called dendronized polymers. The structure of these complex molecular architectures is highly tunable and, therefore, of interest for a wide range of potential applications. The first examples of dendronized polymers prepared by living ring‐opening metathesis polymerization of oxanorbornenedicarboximide macromonomers with poly(alkyl ether) dendrons are reported. Small‐angle X‐ray scattering experiments on bulk samples confirm that the diameter of the individual cylindrical polymers can be tailored by the choice of dendron generation or the length of the hydrocarbon peripheral group. Analysis of the SAXS data based on a core‐shell model indicates that although the diameter of the cylinder increases with generation, the size of the core does not change; this suggests that these dendrons only loosely encapsulate the polymer backbone. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3221–3239 相似文献
525.
This article is a short overview of basic principles, methods and instrumentation of phasing methods based on anomalous scattering for X-ray macromolecular crystallography (MX). 相似文献
526.
Elise Salanouve Sandrine Guillou Marine Bizouarne Frédéric J. Bonhomme Yves L. Janin 《Tetrahedron》2012,68(15):3165-3171
From the condensation between 1,1-dimethoxyethene and anhydrides, synthetically useful β,β–dimethoxy–α,β-unsaturated ketones were prepared. Upon addition of hydrazine, followed by iodination, 4-iodinated 3-methoxypyrazoles were obtained. The occurrence of a side compound also provided insights in the scope of this synthesis. In a second part, 1-(4-chlorophenyl)-3,3-dimethoxyprop-2-en-1-one was obtained from 1,1-dimethoxyethene and 4-chlorobenzoylchloride. The subsequent addition of hydrazine or phenylhydrazine led to 5-(4-chlorophenyl)-3-methoxy-1H-pyrazole or 1-phenyl-5-(4-chlorophenyl)-3-methoxypyrazole in unprecedented 64 or 54% overall yield. Unexpectedly, addition of 2-pyridylhydrazine led to the 2-([1,2,4]triazolo[4,3-a]pyridin-3-yl)-1-(4-chlorophenyl) ethanone. This led us to design original conditions, which led to the target 1-(2-pyridyl)-5-(4-chlorophenyl)-3-methoxypyrazole in a 39% overall yield. Additional examples are provided, starting from various carboxychlorides. 相似文献
527.
Marine ReynaudPrabeer Barpanda Gwenaëlle RousseJean-Noël Chotard Brent C. MelotNadir Recham Jean-Marie Tarascon 《Solid State Sciences》2012,14(1):15-20
Our work in metal fluorosulphate chemistry, which was triggered by the discovery of the tavorite-phase of LiFeSO4F, has unveiled many novel Li- and Na-based phases with desirable electrochemical and/or transport properties. Further exploring this rich crystal chemistry, we have synthesized the Na-based magnesium, copper and zinc fluorosulphates, which crystallise in the maxwellite (tavorite-like framework) structure just as their Fe and Co counterparts, which were previously reported. These phases show ionic conductivities in the range of ∼10−7 S cm−1 or ∼10−11 S cm−1 depending upon their synthesis process and no reversible electrochemical activity versus Na. 相似文献
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