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991.
André Laschewsky Erik Wischerhoff Steffen Denzinger Helmut Ringsdorf Arnaud Delcorte Patrick Bertrand 《Chemistry (Weinheim an der Bergstrasse, Germany)》1997,3(1):34-38
Functional polyanions were prepared by copolymerization of sulfopropyl acrylate and sulfopropyl methacrylate with monomers bearing triaminopyrimidine or barbituric acid functionalities, respectively. Functionalized polyelectrolyte multilayers were assembled from these copolymers by stepwise alternating adsorption with poly(choline methacrylate). These multilayers are suited for molecular recognition of substrates that are complementary to the functional groups incorporated. Thus, multilayers containing triaminopyrimidine moieties selectively bind barbituric acid, and vice versa, when exposed to solutions of the 1:1 complex of barbituric acid and triaminopyrimidine. The molecular recognition process was monitored by UV/Vis spectroscopy, time-of-flight secondary ion mass spectroscopy (ToF-SIMS), and photoelectron spectroscopy (XPS). Remarkably, after successful recognition and binding of the complementary substrates to the multilayers, the stepwise layering could be continued. 相似文献
992.
Degradations photothermiques de polyethylenes reticules—I: Influence de noirs de carbone commerciaux
Introduction of small quantities (<1%) of carbon black in branched polyethylene induces a photothermic degradation at temperatures >70°. An interpretation of variations in the rate of degradation, measured by i.r. absorption or by deformation, with the percentage of carbon black has been given. The effects of different commercial samples of carbon black have been compared. 相似文献
993.
Ab initio molecular orbital calculations of the transition states and barrier heights for the addition of atomic hydrogen to fluoroactylene and 1,1-difluoroethylene are presented. The relative reactivity of these compounds and the regioselectivity of the addition reactions are analyzed in terms of chemically interpretable contributions by means of the energy decomposition scheme proposed by Morokuma. The usual PMO approach of the problem is discussed in this context. A rationalization of some of the experimental rules of radical reactivity is given. 相似文献
994.
Jacques Lacoste Rene Arnaud Jacques Lemaire 《Journal of polymer science. Part A, Polymer chemistry》1984,22(12):3885-3893
Direct evidence of the TiO2 and ZnO photocatalytic decomposition of tert-butyl hydroperoxide and atactic polypropylene hydroperoxides in solution is reported. Molecular and macromolecular hydroperoxides behaved similarly. Untreated TiO2 in the rutile form was a far more efficient photocatalyst than ZnO in solution; the photoactivities of both pigments were limited on preferential absorption sites. In the solid state no preferential reaction sites were observed. When added to preoxidized atactic polypropylene both pigments were photocatalysts of the formation of macromolecular hydroperoxides and of their decomposition. The photoreactivities of untreated TiO2 and ZnO varied less than in solution. 相似文献
995.
Minardi S Gopal A Tatarakis M Couairon A Tamosauskas G Piskarskas R Dubietis A Di Trapani P 《Optics letters》2008,33(1):86-88
By means of a quantitative shadowgraphic method, we performed a space-time characterization of the refractive index variation and transient absorption induced by a light-plasma filament generated by a 120 fs laser pulse in water. The formation and evolution of the plasma channel in the proximity of the nonlinear focus were observed with a 23 fs time resolution. 相似文献
996.
Arnaud Delcorte 《Applied Surface Science》2008,255(4):954-958
This contribution reviews the state-of-the-art in the domains of molecular imaging and depth profiling, the two methodological platforms required for 3D molecular imaging by secondary ion mass spectrometric (SIMS). Using molecular dynamics calculations, it also describes some of the mechanisms that make cluster projectiles such as C60 so different for organic sample analysis. The discussion addresses issues that deserve proper attention on the way to 3D molecular imaging in SIMS, such as ultimate lateral resolution, limited molecular yields, chemical effects and damage, and highlights solutions currently in embryo in the many research teams concerned by 3D molecular imaging. 相似文献
997.
Bodart JF Wieruszeski JM Amniai L Leroy A Landrieu I Rousseau-Lescuyer A Vilain JP Lippens G 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2008,192(2):252-257
The observation by NMR spectroscopy of microinjected 15N-labelled proteins into Xenopus laevis oocytes might open the way to link structural and cellular biology. We show here that embedding the oocytes into a 20% Ficoll solution maintains their structural integrity over extended periods of time, allowing for the detection of nearly physiological protein concentrations. We use these novel conditions to study the neuronal Tau protein inside the oocytes. Spectral reproducibility and careful comparison of the spectra of Tau before and after cell homogenization is presented. When injecting Tau protein into immature oocytes, we show that both its microtubule association and different phosphorylation events can be detected. 相似文献
998.
Fantine Nivet Laurent Bergonzini Pierre-Etienne Mathé Aurélie Noret Gaël Monvoisin Amos Majule 《Isotopes in environmental and health studies》2018,54(4):352-369
Tropical rainfall isotopic composition results from complex processes. The climatological and environmental variability in East Africa increases this complexity. Long rainfall isotope datasets are needed to fill the lack of observations in this region. At Kisiba Masoko, Tanzania, rainfall and rain isotopic composition have been monitored during 6 years. Mean year profiles allow to analyse the seasonal variations. The mean annual rainfall is 2099?mm with a rain-weighted mean composition of ?3.2?‰ for δ18O and ?11.7?‰ for δ2H. The results are consistent with available data although they present their own specificity. Thus, if the local meteoric water line is δ2H?=?8.6 δ18O?+?14.8, two seasonal lines are observed. The seasonality of the isotopic composition in rain and deuterium excess has been compared with precipitating air masses backtracking trajectories to characterize a simple scheme of vapour histories. The three major oceanic sources have two moisture signatures with their own trajectory histories: one originated from the tropical Indian Ocean at the beginning of the rainy season and one from the Austral Ocean at its end. The presented isotopic seasonality depends on the balance of the intertropical front and provides a useful dataset to improve the knowledge about local processes. 相似文献
999.
Borot A Malvache A Chen X Douillet D Iaquianiello G Lefrou T Audebert P Geindre JP Mourou G Quéré F Lopez-Martens R 《Optics letters》2011,36(8):1461-1463
We report the first demonstration of high-harmonic generation from plasma mirrors at a 1 kHz repetition rate. Harmonics up to nineteenth order are generated at peak intensities close to 101? W/cm2 by focusing 1 mJ, 25 fs laser pulses down to 1.7 μm FWHM spot size without any prior wavefront correction onto a moving target. We minimize target surface motion with respect to the laser focus using online interferometry to ensure reproducible interaction conditions for every shot and record data at 1 kHz with unprecedented statistics. This allows us to unambiguously identify coherent wake emission as the main generation mechanism. 相似文献
1000.
Arnaud Liefooghe 《4OR: A Quarterly Journal of Operations Research》2011,9(2):219-222
This is a summary of the author’s PhD thesis supervised by Laetitia Jourdan and El-Ghazali Talbi and defended on 8 December
2009 at the Université Lille 1. The thesis is written in French and is available from . This work deals with the design, implementation and experimental analysis of metaheuristics for solving multiobjective optimisation
problems, with a particular interest on hard and large combinatorial problems from the field of logistics. After focusing
on a unified view of multiobjective metaheuristics, we propose new cooperative, adaptive and parallel approaches. The performance
of these methods are experimented on a scheduling and a routing problem involving two or three objective functions. We finally
discuss how to adapt such metaheuristics during the search process in order to handle uncertainty that may occur from many
different sources. 相似文献