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991.
992.
Sophie A. W. Calabretto James P. Denier Trent W. Mattner 《Theoretical and Computational Fluid Dynamics》2016,30(4):295-312
Imparting a sudden rotation to a torus (or other symmetric smooth object) in an otherwise quiescent, viscous fluid serves to generate boundary layers at the object’s surface. These boundary layers are known to exhibit a finite-time singularity at the equator which manifests in a thickening of the boundary layer and subsequent development of an equatorial jet. Here we consider the post-collision flow dynamics, demonstrating that the equatorial jet serves to shed a finite amplitude toroidal vortex pair. The radial jet is also shown to develop an absolute instability at suitably high Reynolds numbers. 相似文献
993.
994.
Eva‐Maria Christ Sophie S. Müller Elena Berger‐Nicoletti Holger Frey 《Journal of polymer science. Part A, Polymer chemistry》2014,52(19):2850-2859
Synthesis and characterization of novel hydroxyl‐functionalized oxetane‐inimers with varied alkyl chain length—3‐hydroxymethyl‐3‐methoxymethyloxetane, 3‐hydroxymethyl‐3‐propoxymethyloxetane, and 3‐hexoxymethyl‐3‐hydroxymethyloxetane—is reported. Cationic ring‐opening polymerization of these latent, cyclic AB2‐monomers leads to hyperbranched (hb) polyether polyols with degrees of branching between 34 and 69%, confirmed by inverse‐gated (IG) 13C NMR spectroscopy. The hyperbranching polymerization yielded apparent molecular weights (Mn) ranging from 500 to 2500 g mol?1 (size exclusion chromatography). Remarkably, by copolymerization of 1,1,1‐tris(4‐hydroxyphenyl)ethane as a “focal” unit, polymerization under slow monomer addition conditions lead to higher apparent molecular weights up to 11,220 g mol?1. The end groups of the hb polymers were studied via matrix‐assisted laser desorption/ionization time of flight mass and NMR spectrometry. By varying the alkyl chain length, tailoring of the solubility and glass transition temperatures of the materials is possible. Potential applications range from macroinitiators with defined polarity to tailoring of surface properties of antifouling materials. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2850–2859 相似文献
995.
Eric Macia Monserrat Vazquez-Rojas Alessia Robiolo Racha Fayad Sophie Ablanet Isabelle Mus-Veteau Fabien Fontaine-Vive Mohamed Mehiri Frdric Luton Michel Franco 《Molecules (Basel, Switzerland)》2021,26(4)
Breast cancer is a major disease for women worldwide, where mortality is associated with tumour cell dissemination to distant organs. While the number of efficient anticancer therapies increased in the past 20 years, treatments targeting the invasive properties of metastatic tumour cells are still awaited. Various studies analysing invasive breast cancer cell lines have demonstrated that Arf6 is an important player of the migratory and invasive processes. These observations make Arf6 and its regulators potential therapeutic targets. As of today, no drug effective against Arf6 has been identified, with one explanation being that the activation of Arf6 is dependent on the presence of lipid membranes that are rarely included in drug screening. To overcome this issue we have set up a fluorescence-based high throughput screening that follows overtime the activation of Arf6 at the surface of lipid membranes. Using this unique screening assay, we isolated several compounds that affect Arf6 activation, among which the antibiotic chlortetracycline (CTC) appeared to be the most promising. In this report, we describe CTC in vitro biochemical characterization and show that it blocks both the Arf6-stimulated collective migration and cell invasion in a 3D collagen I gel of the invasive breast cancer cell line MDA-MB-231. Thus, CTC appears as a promising hit to target deadly metastatic dissemination and a powerful tool to unravel the molecular mechanisms of Arf6-mediated invasive processes. 相似文献
996.
Pit Boden Patrick Di Martino-Fumo Tobias Bens Sophie Steiger Uta Albold Prof. Dr. Gereon Niedner-Schatteburg Prof. Dr. Markus Gerhards Prof. Dr. Biprajit Sarkar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(51):12959-12964
The development of NIR emitters based on earth-abundant elements is an important goal in contemporary science. We present here Cr(0), Mo(0), and W(0) carbonyl complexes with a pyridyl-mesoionic carbene (MIC) based ligand. A detailed photophysical investigation shows that all the complexes exhibit dual emissions in the VIS and in the NIR region. The emissive excited states are assigned to two distinct triplet states by time-resolved emission and step-scan FTIR spectroscopy at variable temperature, supported by density functional theory. In particular, the NIR emissive triplet state exhibits unprecedented lifetimes of up to 600±10 ns and quantum yields reaching 1.7 ⋅ 10−4 at room temperature. These are the first examples of Cr(0), Mo(0) and W(0) complexes that emit in the NIR II region. 相似文献
997.
Sophie D. Baton Michel Koenig Perceval Guillou Brnice Loupias Alessandra Benuzzi-Mounaix Julien Fuchs Christophe Rousseaux Laurent Gremillet Dimitri Batani Alessio Morace Motoaki Nakatsutsumi Ryosuke Kodama Yefim Aglitskiy 《High Energy Density Physics》2007,3(3-4):358-364
We present experimental results on the interaction of short-pulse ultra-high-intensity laser beams with small size (“mass-limited”) targets. Several diagnostics (X-ray spectroscopy, Kα and optical imaging of target rear side) have been simultaneously used in order to characterize the laser-generated fast electron transport and energy deposition into the target material. Our results show that fast electrons are effectively confined inside the target by the induced space charge. This electrostatic confinement opens new opportunities to create “Warm Dense Matter” states characterized by solid-state density and temperatures of the order of a few tens of eV. 相似文献
998.
Sophie Racine Florian de Nanteuil Eloisa Serrano Prof. Dr. Jérôme Waser 《Angewandte Chemie (International ed. in English)》2014,53(32):8484-8487
(Carbo)nucleoside derivatives constitute an important class of pharmaceuticals, yet there are only few convergent methods to access new analogues. Here, we report the first synthesis of thymine‐, uracil‐, and 5‐fluorouracil‐substituted diester donor–acceptor cyclopropanes and their use in the indium‐ and tin‐catalyzed [3+2] annulations with aldehydes, ketones, and enol ethers. The obtained diester products could be easily decarboxylated and reduced to the corresponding alcohols. The method gives access to a broad range of new (carbo)nucleoside analogues in only four or five steps and will be highly useful for the synthesis of libraries of bioactive compounds. 相似文献
999.
PMLABe Diol Synthesized by Ring‐Opening Polymerization of Racemic Benzyl β‐Malolactonate Initiated by Rare‐Earth Trisborohydride Complexes: An Experimental and DFT Study
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Iker del Rosal Teddy Mevel Prof. Dr. Peter W. Roesky Prof. Dr. Laurent Maron Dr. Sophie M. Guillaume 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(44):14387-14402
Polymer diols are a class of polymeric building blocks of high interest for the synthesis of complex macromolecular edifices. Rare‐earth borohydride complexes are known as efficient initiators for the ring‐opening polymerization (ROP) of cyclic esters, directly affording α,ω‐dihydroxy‐telechelic polyesters. Here, were report the direct synthesis of poly(benzyl β‐malolactonate) (PMLABe) diols, from the ROP of racemic (benzyl β‐malolactonate) (rac‐MLABe), a valuable and renewable monomer, initiated by the homoleptic [Ln(BH4)3(thf)3] (Ln=La, Nd, and Sm) complexes. These initiators enabled the controlled ROP of this β‐lactone, affording well‐defined syndiotactic‐enriched (Pr≈0.83) PMLABes (Mn up to 21 300 g mol?1, ÐM≈1.5) as evidenced by size exclusion chromatography, 1H and 13C NMR spectroscopy, and MALDI‐ToF mass spectrometry analyses. The first and second insertions of rac‐MLABe, as assessed by DFT calculations, revealed more favorable stationary front‐side than migratory back‐side insertions, the thermodynamically and kinetically competitive ROP on two distinct arms with that on a one arm‐only, and the thermodynamically slightly favored formation of syndiotactic‐enriched PMLABes. 相似文献
1000.
Silver‐Free Two‐Component Approach in Gold Catalysis: Activation of [LAuCl] Complexes with Derivatives of Copper,Zinc, Indium,Bismuth, and Other Lewis Acids
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Weizhen Fang Dr. Marc Presset Dr. Amandine Guérinot Dr. Christophe Bour Dr. Sophie Bezzenine‐Lafollée Prof. Dr. Vincent Gandon 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(18):5439-5446
Complexes of type [LAuCl] (L=phosphine, phosphite, NHC and others) are widely employed in homogeneous catalysis, however, they are usually inactive as such and must be used jointly with a halide scavenger. To date, this role has mostly been entrusted to silver salts (AgSbF6, AgPF6, AgBF4, AgOTf, etc.). However, silver salts can be the source of deactivation processes or side reactions, so it is sometimes advisable to use silver‐free cationic gold complexes, which can be difficult to synthesize and to handle compared with the more robust chloride. We show in this study that various Lewis acids of the transition and main group metal families are expedient substitutes to silver salts. We have tested CuI, CuII, ZnII, InIII, SiIV, BiIII, and other salts in a variety of typical AuI‐catalyzed transformations, and the results have revealed that [LAuCl] can form active species in their presence. 相似文献