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141.
The electronic transport of monolayer graphene devices is studied before and after in situ deposition of a sub-monolayer coating of osmium adatoms. Unexpectedly, and unlike all other metallic adatoms studied to date, osmium adatoms shift the charge neutrality point to more positive gate voltages. This indicates that osmium adatoms act as electron acceptors and thus leave the graphene hole-doped. Analysis of transport data suggest that Os adatoms behave as charged impurity scatterers, albeit with a surprisingly low charge-doping efficiency. The charge neutrality point of graphene is found to vary non-monotonically with gate voltage as the sample is warmed to room temperature, suggesting that osmium diffuses on the surface but is not completely removed. 相似文献
142.
Hossain M. A. Siddiki S. M. A. Hakim Elias M. Rahman M. M. Jamil M. A. R. 《Russian Journal of Organic Chemistry》2020,56(10):1806-1814
Russian Journal of Organic Chemistry - Methods have been reported for the preparation of ω-functionalized alkyl maltoside and glycoside detergents via a simple and inexpensive synthetic route.... 相似文献
143.
Julia Holz Camilla Pfeffer Hualiang Zuo Dennis Beierlein Gunther Richter Elias Klemm Ren Peters 《Angewandte Chemie (International ed. in English)》2019,58(30):10330-10334
Gold nanoparticle catalysts are important in many industrial production processes. Nevertheless, for traditional C ?C cross‐coupling reactions they have been rarely used and Pd catalysts usually give a superior performance. Herein we report that in situ formed gold metal nanoparticles are highly active catalysts for the cross coupling of allylstannanes and activated alkylbromides to form C ?C bonds. Turnover numbers up to 29 000 could be achieved in the presence of active carbon as solid support, which allowed for convenient catalyst recovery and reuse. The present study is a rare case where a gold metal catalyst is superior to Pd catalysts in a cross‐coupling reaction of an organic halide and an organometallic reagent. 相似文献
144.
Elias Al Sarraf Christophe Almarcha Joël Quinard Basile Radisson Bruno Denet Pedro Garcia-Ybarra 《Proceedings of the Combustion Institute》2019,37(2):1783-1789
Hydrodynamic flame instabilities are studied in a Hele-Shaw burner. By studying the development of perturbations, starting from a 2D Bunsen flame at the top of the burner, growth rates are measured for propane and methane–air mixtures, and compared to theoretical predictions. It is found that the dispersion relation in a Hele-Shaw cell has the same dependence with wavenumber as the one predicted in tubes. Markstein numbers relative to fresh gases are obtained for propane and methane flames and compared to the literature. 相似文献
145.
Peter Elias 《Proceedings of the American Mathematical Society》1997,125(4):1111-1121
We introduce a uniform way of classifying thin sets of harmonic analysis related to absolute convergence of trigonometric series. This classification covers classical classes and yields two new ones ( and . We study interrelation between these classes concerning combinatorial structure of thin sets.
146.
147.
E. J. De França E. A. De Nadai Fernandes M. A. Bacchi C. Elias 《Journal of Radioanalytical and Nuclear Chemistry》2008,276(1):221-228
The accumulation of chemical elements in biological compartments is one of the strategies of tropical species to adapt to
a low-nutrient soil. This study focuses on the Atlantic Forest because of its eco-environmental importance as a natural reservoir
of chemical elements. About 20 elements were determined by INAA in leaf, soil, litter and epiphyte compartments. There was
no seasonality for chemical element concentrations in leaves, which probably indicated the maintainance of chemical elements
in this compartment. Considering the estimated quantities, past deforestation events could have released large amounts of
chemical elements to the environment. 相似文献
148.
Pisani E Fattal E Paris J Ringard C Rosilio V Tsapis N 《Journal of colloid and interface science》2008,326(1):66-71
In a strategy to develop more stable ultrasound contrast agents (UCAs), we have designed a process to obtain nano/microcapsules with a single core of liquid perfluorocarbon within a biodegradable polymeric shell of homogeneous thickness. During the optimization of perfluorooctyl bromide (PFOB) encapsulation by solvent emulsion-evaporation, a marked influence of surfactants has been observed. While sodium cholate leads to spherical capsules of homogeneous thickness, sodium taurocholate induces to the formation of “acorn”-particles with one hemisphere of PFOB and another one of PLGA, and polyvinyl alcohol is responsible for the coexistence of both morphologies. Whereas the theoretical model proposed by Torza and Mason [J. Colloid Interface Sci. 33 (1970) 67] fails to predict the observed morphologies, microscopic observations of the evaporation and interfacial tension measurements provide an insight into the mechanism of formation of these structures. Most probably, there is a competition between PLGA and the surfactant stabilizing the emulsion at the dichloromethane–water interface. If PLGA is able to adsorb at the interface, the core–shell morphology is obtained, otherwise the acorn morphology is preferentially formed. When the surfactant rearrangement at the interface is long (>30 min), a coexistence of morphologies can be obtained. 相似文献
149.
Single-particle kinetic studies of the reaction between oleic acid and O 3 have been conducted on two different types of core particles: polystyrene latex (PSL) and silica. Oleic acid was found to adsorb to both particle types in multilayer islands that resulted in an adsorbed layer of a total volume estimated to be less than one monolayer. The rate of the surface reaction between surface-adsorbed oleic acid and O 3 has been shown for the first time to be influenced by the composition of the aerosol substrate in a mixed organic/inorganic particle. A Langmuir-Hinshelwood mechanism was applied to the observed dependence of the pseudo-first-order rate constant with [O 3], and the resulting fit parameters for the ozone partition coefficient ( K O 3 ) and maximum first order rate constant ( k 1,max ) suggest that the reaction proceeded faster on the less polar PSL core at lower [O 3] due to the increased residence time of O 3 on the PSL surface, but the reaction was ultimately more efficient on the silica surface at high [O 3]. Values for the uptake coefficient, gamma oleic , for reaction of oleic acid on PSL spheres decrease from 2.5 x 10 (-5) to 1 x 10 (-5) with increasing [O 3] from 4 to 25 ppm and overlap at high [O 3] with the estimated values for gamma oleic on silica, which decrease from 1.6 x 10 (-5) to 1.3 x 10 (-5). The relationship between gamma oleic and the more common expression for gamma O 3 is discussed. 相似文献
150.
A high performance liquid chromatography (HPLC) method for the detection and quantitation of acetaldehyde, glyceraldehyde, pyruvic acid, 2-ketoglutaric acid, and formaldehyde in wine, based on the formation of the 2,4-dinitrophenylhydrazones, is presented. These carbonyl compounds often result from the chemical oxidation of major wine components, and are known to affect flavor and color stability. Their analysis in wine is complicated due to their instability and their tendency to react reversibly with bisulfite to form α-hydroxysulfonates. Published methods that break down the sulfonates for the quantitation of total carbonyls in wine involve alkaline hydrolysis of sulfite-bound carbonyls, but we show, for the first time, that this alkaline treatment step significantly increases the concentration of carbonyls during analysis. A solution based on oxygen exclusion is described. The technique offers good specificity, reproducibility (%RSD 0.45-10.6), and limits of detection (1.29-7.53 μg L−1). The method was successfully used to monitor concentration changes of these compounds in both white and red wines. 相似文献