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排序方式: 共有189条查询结果,搜索用时 624 毫秒
31.
Preti D Resta C Squarcialupi S Fachinetti G 《Angewandte Chemie (International ed. in English)》2011,50(52):12551-12554
AUROlite, consisting of gold supported on titania (picture shows extrudates in a steel net cage), is a robust catalyst for the production of catalyst-free HCOOH/NEt(3) adducts from H(2), CO(2), and neat NEt(3). Pure HCOOH is freed from the adducts by amine exchange. 相似文献
32.
We study a 2 × 2 system of balance laws that describes the evolution of a granular material (avalanche) flowing downhill.
The original model was proposed by Hadeler and Kuttler (Granul Matter 2:9–18, 1999). The Cauchy problem for this system has
been studied by the authors in recent papers (Amadori and Shen in Commun Partial Differ Equ 34:1003–1040, 2009; Shen in J
Math Anal Appl 339:828–838, 2008). In this paper, we first consider an initial-boundary value problem. The boundary condition
is given by the flow of the incoming material. For this problem we prove the global existence of BV solutions for a suitable
class of data, with bounded but possibly large total variations. We then study the “slow erosion (or deposition) limit”. We
show that, if the thickness of the moving layer remains small, then the profile of the standing layer depends only on the
total mass of the avalanche flowing downhill, not on the time-law describing the rate at which the material slides down. More
precisely, in the limit as the thickness of the moving layer tends to zero, the slope of the mountain is provided by an entropy
solution to a scalar integro-differential conservation law. 相似文献
33.
Debora Clever 《PAMM》2010,10(1):575-576
We give an overview about several verification tools to study consistency between discrete optimization problem and discrete derivatives when using independent discretization schemes for state and adjoint systems within the context of optimal control problems. We present strategies that detect impreciseness within a considered quantity without any additional effort. They are therefore a suitable tool to control the grid refinement within a multilevel setting. More detailed tools are useful to verify the problem implementation and to analyze the quantities discretization error order. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
34.
Debora Amadori 《Nonlinear Analysis: Theory, Methods & Applications》2010,72(5):2527-2386
We consider a strictly hyperbolic system of balance laws in one space variable, that represents a simple model for a fluid flow in the presence of phase transitions. The state variables are specific volume, velocity and mass-density fraction λ of the vapor in the fluid. A reactive source term drives the dynamics of the phase mixtures; such a term depends on a relaxation parameter and involves an equilibrium pressure, allowing for metastable states.First we prove the global existence of weak solutions to the Cauchy problem, where the initial datum for λ is close either to 0 or 1 (the pure phases) and has small total variation, while the initial variations of pressure and velocity are not necessarily small. Then we consider the relaxation limit and prove that the weak solutions of the full system converge to those of the reduced system. 相似文献
35.
Victor B. Tinti Debora Marani Andre S. Ferlauto Fabio C. Fonseca Vincenzo Esposito Daniel Z. de Florio 《Particle & Particle Systems Characterization》2020,37(2):1900472
A fast and accurate experimental method is demonstrated to assess the fraction of exsolved metallic nanoparticles using magnetic measurements. As a benchmark, nanometric metallic nickel exsolved from (La1−xSrx)(Cr1−yNiy)O3−δ is used for its high relevance as a solid oxide fuel cell component. The method is based on the difference in the magnetic response of the exsolved metallic nickel (ferromagnetic) and Sr-doped lanthanum chromite ceramic matrix (paramagnetic). The exsolved nickel results in coherent nanoparticles pinned on the surface of the Sr-doped lanthanum chromite ceramic matrix, as evidenced by electron microscopy analyses. The results obtained indicate the procedure as a fast and sensitive method to study the exsolution of ferromagnetic nanoparticles. 相似文献
36.
Bianco Prevot A Fabbri D Pramauro E Baiocchi C Medana C 《Journal of chromatography. A》2008,1202(2):145-154
High-performance liquid chromatography coupled to ultraviolet diode array detection and electrospray ionization mass spectrometry was applied to monitor the photocatalytic degradation mediated by TiO2 of three sulfonated monoazo dyes (Orange I, Orange II, and Ethylorange) present in aqueous solution. Photobleaching, organic carbon, nitrogen and sulfur evolution were also followed during the process. Delayed carbon mineralization was observed with respect to both dyes disappearance and photobleaching, due to the formation of transient intermediate compounds which were in turn completely degraded. Among the intermediates produced during the initial degradation steps the formation of several hydroxylated derivatives, mostly coloured, was evidenced. The MS(2) spectra allowed one to formulate hypothesis about the OH attack positions; a peculiar reactivity of the azo moiety was shown by Orange I and Orange II. 相似文献
37.
Vanessa C. Gonçalves Marystela Ferreira Clarissa A. Olivati Marcos R. Cardoso Cleber R. Mendonça Debora T. Balogh 《Colloid and polymer science》2008,286(12):1395-1401
The conductivity and luminescence of conjugated polymers may be combined with the photoisomerization capability of azobenzene
materials to achieve unique properties for a variety of applications, particularly if conjugated polymers with azobenzene
side chains are processed as nanostructured films. In this study, we report on Langmuir–Blodgett (LB) films of a polythiophene-bearing
azobenzene moieties, which displayed photoluminescence, thermochromism, electroactivity, and photoinduced birefringence. The
latter three properties were enhanced in the LB films, as compared to spin-coated films of the polyazothiophene, and this
has been attributed to differences in film morphology that could be probed with atomic force microscopy. 相似文献
38.
Pump−probe experiments at the TEMPO beamline using the low‐α operation mode of Synchrotron SOLEIL 下载免费PDF全文
Mathieu G. Silly Tom Ferté Marie Agnes Tordeux Debora Pierucci Nathan Beaulieu Christian Chauvet Federico Pressacco Fausto Sirotti Horia Popescu Victor Lopez-Flores Marina Tortarolo Maurizio Sacchi Nicolas Jaouen Philippe Hollander Jean Paul Ricaud Nicolas Bergeard Christine Boeglin Bharati Tudu Renaud Delaunay Jan Luning Gregory Malinowski Michel Hehn Cédric Baumier Franck Fortuna Damjan Krizmancic Luigi Stebel Rudi Sergo Giuseppe Cautero 《Journal of synchrotron radiation》2017,24(4):886-897
The SOLEIL synchrotron radiation source is regularly operated in special filling modes dedicated to pump–probe experiments. Among others, the low‐α mode operation is characterized by shorter pulse duration and represents the natural bridge between 50 ps synchrotron pulses and femtosecond experiments. Here, the capabilities in low‐α mode of the experimental set‐ups developed at the TEMPO beamline to perform pump–probe experiments with soft X‐rays based on photoelectron or photon detection are presented. A 282 kHz repetition‐rate femtosecond laser is synchronized with the synchrotron radiation time structure to induce fast electronic and/or magnetic excitations. Detection is performed using a two‐dimensional space resolution plus time resolution detector based on microchannel plates equipped with a delay line. Results of time‐resolved photoelectron spectroscopy, circular dichroism and magnetic scattering experiments are reported, and their respective advantages and limitations in the framework of high‐time‐resolution pump–probe experiments compared and discussed. 相似文献
39.
Barbara Chiavarino Dr. Maria Elisa Crestoni Prof. Simonetta Fornarini Prof. Francesco Lanucara Dr. Joel Lemaire Dr. Philippe Maître Prof. Debora Scuderi Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(33):8185-8195
Anion–π interactions between a π‐acidic aromatic system and an anion are gaining increasing recognition in chemistry and biology. Herein, the binding features of an electron‐deficient aromatic system (1,3,5‐trinitrobenzene (TNB)) and selected anions (OH?, Br?, and I?) are examined in the gas phase by using the combined information derived from collision‐induced dissociation experiments at variable energy, infrared multiple‐photon dissociation spectroscopy, and quantum chemical calculations. We provide spectroscopic evidence for two different structural motifs of anion–arene complexes depending on the nature of the anion. The TNB–OR? complexes (R=H, or alkyl groups which were studied earlier) adopt an anionic σ‐complex structure whereby RO? attacks the aromatic ring with covalent bond formation, and develops a tetrahedral ring carbon bound to H and OR. The halide complexes rather conform to a structure in which the TNB moiety is hardly altered, and the halogen is placed on an unsubstituted carbon atom over the periphery of the ring at a C–X distance that is appreciably longer than a typical covalent bond length. The ensuing structural motif, previously characterized in the solid state and named weak σ interaction, is now confirmed by an IR spectroscopic assay in the gas phase, in which the sampled species are unperturbed by crystal packing or solvation effects. 相似文献
40.
Cristina Jimnez-Holgado Paola Calza Debora Fabbri Federica Dal Bello Claudio Medana Vasilios Sakkas 《Molecules (Basel, Switzerland)》2021,26(17)
This study investigated the direct and indirect photochemical degradation of citalopram (CIT), a selective serotonin reuptake inhibitor (SSRI), under natural and artificial solar radiation. Experiments were conducted in a variety of different operating conditions including Milli-Q (MQ) water and natural waters (lake water and municipal WWT effluent), as well as in the presence of natural water constituents (organic matter, nitrate and bicarbonate). Results showed that indirect photolysis can be an important degradation process in the aquatic environment since citalopram photo-transformation in the natural waters was accelerated in comparison to MQ water both under natural and simulated solar irradiation. In addition, to investigate the decontamination of water from citalopram, TiO2-mediated photocatalytic degradation was carried out and the attention was given to mineralization and toxicity evaluation together with the identification of by-products. The photocatalytic process gave rise to the formation of transformation products, and 11 of them were identified by HPLC-HRMS, whereas the complete mineralization was almost achieved after 5 h of irradiation. The assessment of toxicity of the treated solutions was performed by Microtox bioassay (Vibrio fischeri) and in silico tests showing that citalopram photo-transformation involved the formation of harmful compounds. 相似文献