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151.
Zhilai Hong Arnaud Bolard Caroline Giraud Sbastien Prvost Grgory Genta‐Jouve Christiane Deregnaucourt Susanne Hussler Katy Jeannot Yanyan Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(10):3210-3214
Pseudomonas aeruginosa displays an impressive metabolic versatility, which ensures its survival in diverse environments. Reported herein is the identification of rare azetidine‐containing alkaloids from P. aeruginosa PAO1, termed azetidomonamides, which are derived from a conserved, quorum‐sensing regulated nonribosomal peptide synthetase (NRPS) pathway. Biosynthesis of the azetidine motif has been elucidated by gene inactivation, feeding experiments, and biochemical characterization in vitro, which involves a new S‐adenosylmethionine‐dependent enzyme to produce azetidine 2‐carboxylic acid as an unusual building block of NRPS. The mutants of P. aeruginosa unable to produce azetidomonamides had an advantage in growth at high cell density in vitro and displayed rapid virulence in Galleria mellonella model, inferring functional roles of azetidomonamides in the host adaptation. This work opens the avenue to study the biological functions of azetidomonamides and related compounds in pathogenic and environmental bacteria. 相似文献
152.
Arnaud Imberdis Guillaume Lefvre Thibault Cantat 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(48):17375-17379
The selective decarbonylation of formic acid was achieved under transition‐metal‐free conditions. Using a liquid chemical‐looping strategy, the thermodynamically favored dehydrogenation of formic acid was shut down, yielding a pure stream of CO with no H2 or CO2 contamination. The transformation involves a two‐step sequence where methanol is used as a recyclable looping agent to yield methylformate, which is subsequently decomposed to carbon monoxide using alkoxides as catalysts. 相似文献
153.
Eva Pospisilova Alexis Renaud Marc Poorteman Marjorie Olivier Ludovic Dumas Philippe Dubois Leila Bonnaud Konstantin Moshkunov Bernard Nysten Arnaud Delcorte 《Surface and interface analysis : SIA》2019,51(6):674-680
Phenol-paraphenylenediamine (P-pPDA) benzoxazines exhibit excellent barrier properties, adequate to protect aluminum alloys from corrosion, and constitute interesting candidates to replace chromate-containing coatings in the aeronautical industry. For the successful application of P-pPDA coatings, it is necessary to decrease the curing temperature to avoid the delamination of the coating while preserving the mechanical properties of the alloy, as well as the barrier properties of the coating. However, decreasing the curing temperature leads to less polymerized films, the extent of which requires a quantitative assessment. While the conversion rate of the polymerization reaction is commonly evaluated for bulk samples using differential scanning calorimetry (DSC), a tool for its evaluation in thin films is missing. Therefore, a new approach was developed for that matter using time-of-flight secondary ion mass spectrometry (ToF-SIMS). The relation between the SIMS data integrated from inside thin films and the DSC results obtained on bulk samples with the same curing cycle allowed to calibrate the SIMS data. With this preliminary calibration of the technique, the polymerization of P-pPDA coatings can be locally determined, at the surface and along the depth of the coating, using dual-beam depth profiling with large argon cluster beam sputtering. 相似文献
154.
Zarafu Irina Badea Mihaela Ioniţă Gabriela Chifiriuc Mariana Carmen Bleotu Coralia Popa Marcela Ioniţă Petre Tatibouët Arnaud Olar Rodica 《Journal of Thermal Analysis and Calorimetry》2019,136(5):1977-1987
Journal of Thermal Analysis and Calorimetry - A series of complexes [Cu(L)(CH3COO)2]·nH2O (L: isonicotinic acid 2-(2-hydroxy-8-substituted-tricyclo[7.3.1.02.7]tridec-13-ylidene)-hydrazones)... 相似文献
155.
Julien Gautier Franck Delmotte Arnaud Jérome Francoise Varnière 《Optics Communications》2008,281(11):3032-3035
A two-channel mirror reflecting both Fe-IX/X (λ = 17.1 nm) and He-II (30.4 nm) resonance lines at near normal incidence has been designed, fabricated and characterized. These two passbands are often chosen in space instruments designed for the observation of the solar corona. The mirror structure used for optimization is a superposition of two periodic multilayers with three components per period. It has been designed by using optimization software with an appropriate merit function. The theoretical reflectivity for both resonance lines can reach 0.25. It is shown that, by using a set of filters, one can select either the Fe-IX/X or the He-II channel. The spectral response of the two-channel mirror has been measured on synchrotron radiation source on a large wavelength range, from 12 nm to 35 nm. Experimental reflectivity reaches 0.32 for the Fe-IX/X line and 0.19 for the He-II line. 相似文献
156.
Vasilyev S Schiller S Nevsky A Grisard A Faye D Lallier E Zhang Z Boyland AJ Sahu JK Ibsen M Clarkson WA 《Optics letters》2008,33(13):1413-1415
A narrow-linewidth mid-IR source based on difference-frequency generation of an amplified 1.5 microm diode laser and a cw Tm-doped fiber laser in orientation-patterned (OP) GaAs has been developed and evaluated for spectroscopic applications. The source can be tuned to any frequency in the 7.6-8.2 microm range with an output power of 0.5 mW. The measured characteristics of the OP-GaAs sample demonstrate a high quality of the material. 相似文献
157.
158.
Romain Plais Guy Gouarin Dr. Anne Gaucher Violette Haldys Arnaud Brosseau Dr. Gilles Clavier Dr. Jean-Yves Salpin Prof. Dr. Damien Prim 《Chemphyschem》2020,21(12):1249-1257
The intrinsic properties of tetrazine as a π-anion receptor and as an on/off recognition probe merged with H-bond ability of an urea motif into a single architecture constitutes a new generation of well-defined anion receptors. Complexation properties directly benefit from the dual and synergistic contribution of tetrazine and urea. In this study, we report on the synthesis and assessment of binding properties to anions of diverse geometries. Association constants have been predicted by theoretical calculations and evaluated by multiple and complementary experimental techniques including electrospray-mass tandem spectroscopy, NMR, UV-visible, steady state fluorescence spectroscopies and time resolved fluorescence. These results provide the basis for a better understanding of both the complexation and the anion-dependent quenching mechanism. 相似文献
159.
160.
Joy Ann Panis Prof. Marine Louis Arnaud Brosseau Shouhei Katao Florencio de los Reyes Prof. Takuya Nakashima Dr. Rémi Métivier Dr. Clémence Allain Prof. Tsuyoshi Kawai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(44):e202201012
We synthesized two bichromophoric difluoroboron-β-diketonates (DFB) connected in para and meta positions by using cyclohexane diamine as a chiral bridge ( para and meta (R/S)-CyDFB ). TD-DFT calculations revealed that the variation in connectivity of the DFB units leads to different spatial arrangements and a chirality inversion of the bichromophoric DFB. Higher gabs values were obtained in (R/S)-CyDFB connected in para as compared to meta position. Aggregation of para (R/S)-CyDFB in mixture of solvents increase the glum values as compared to its monomeric form. Ultrasonication and heating induced the formation of highly ordered nano-helical wires of para (R/S)-CyDFB that increased the glum values to 0.015. On the other hand, meta (R/S)-CyDFB failed to form highly ordered self-assembled wires due to hindered H-binding sites. These observations indicate that the chiroptical properties of DFB bi-chromophore system can be modulated with self-assembly and spatial arrangement of the chromophores. 相似文献