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21.
Miniaturization of analytical instruments has attracted a wide interest in analytical chemistry over the past decade because of the advantages of reduced reagent consumption, better analytical performance, and shorter analysis time. The widespread interest in this field has resulted in efforts to develop chips. For chips involving separation, injection is a key step to achieve efficient and sensitive analysis. This work presents a comparative study of two electrokinetic injection modes in chips: the floating, which has been mainly used up to now, and the dynamic. This study was done with a crossjunction, either with numerical simulations or with experiments. Experiments were carried out with homemade PDMS-glass microsystems involving zonal electrophoresis analysis of five derivatized amino acids. Injected amount, reproducibility, separation efficiency, and analyte discrimination were evaluated and discussed. The experimental results were successfully correlated with numerical simulations. It appeared that the dynamic injection mode is much more appropriate than the floating mode as it is faster (reduction by a factor 2 of the total analysis time here), more reproducible (RSD of peak areas equal to 1.3% (n = 4) instead of 10% (n = 4)), and leads to more efficient separation (about 20% with 3 cm separation channel length) for the same injected amount, whatever the amount, because the sample plug is less dispersed. 相似文献
22.
Pump−probe experiments at the TEMPO beamline using the low‐α operation mode of Synchrotron SOLEIL
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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
23.
H. Dumont B. Delaunay J. Delaunay D.M. De Castro Rizzo A. Brondi P. Cuzzocrea A. Donofrio R. Moro M. Romano F. Terrasi 《Nuclear Physics A》1985,435(1):301-316
Excitation functions of the reactions 12, 13C+48Ti and 30Si+30Si were measured by in-beam γ-ray spectrometry in the energy ranges 20–60 MeV for the 12, 13C induced reactions and 55–126 MeV for the 30Si+30Si reaction. Light-particle angular distributions were measured at 46 MeV and 47.5 MeV for the 13C and 12C induced reactions. Measurements of elastic scattering angular distribution and particle-γ coincidences were carried out for the system 13C+48Ti at 46 MeV. The limitation to complete fusion detected for the system 30Si+30Si appears to be related to entrance channel effects and is well reproduced by a barrier penetration calculation using the KNS potential. The angular distribution measurements carried out for the 12C+48Ti and 13C+48Ti systems allowed to identify an incomplete fusion mechanism with emission of direct α-particles before the formation of a fully equilibrated system. 相似文献
24.
Dr. Keihann Yavari Dr. Wylliam Delaunay Dr. Nicolas De Rycke Thibault Reynaldo Dr. Paul Aillard Dr. Monika Srebro-Hooper Victoria Y. Chang Dr. Gilles Muller Dr. Denis Tondelier Bernard Geffroy Dr. Arnaud Voituriez Dr. Angela Marinetti Prof. Muriel Hissler Dr. Jeanne Crassous 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(20):5303-5310
Herein, the experimental physicochemical and chiroptical properties of a series of phosphahelicenes are reported, focusing on their UV/Vis absorption, luminescence, electronic circular dichroism, optical rotations, and circularly polarized luminescence. Furthermore, detailed analysis of absorption and ECD spectra performed with the help of quantum-chemical calculations allowed us to highlight general features of these helicenic phosphines. Finally, due to well-suited electrochemical properties and thermal stability, the systems were successfully used as emitters in organic light-emitting diodes. 相似文献
25.
Rueff JP Itié JP Taguchi M Hague CF Mariot JM Delaunay R Kappler JP Jaouen N 《Physical review letters》2006,96(23):237403
We report on the most complete investigation to date of the -electron properties at the transition in elemental Ce by resonant inelastic x-ray scattering (RIXS). The Ce 2p3d-RIXS spectra were measured directly in the bulk material as a function of pressure through the transition. The spectra were simulated within the Anderson impurity model. The occupation number n(f) and f double occupancy were derived from the calculations in both gamma and alpha phases in the ground state. We find that the electronic structure changes result mainly from band formation of 4f electrons which concurs with reduced electron correlation and increased Kondo screening at high pressure. 相似文献
26.
Frère P Raimundo JM Blanchard P Delaunay J Richomme P Sauvajol JL Orduna J Garin J Roncali J 《The Journal of organic chemistry》2003,68(19):7254-7265
Three series of thiophene-based pi-conjugated oligomers built with different combinations of thiophene cycles and double bonds have been synthesized and characterized. The analysis of the chain length dependence of the electronic, electrochemical, and vibrational properties of the three series of oligomers has been carried out using cyclic voltammetry, UV-vis, IR, and Raman spectroscopies. These various investigations provide consistent results showing that incorporation of ethylenic linkages in an oligothiophene structure leads to a faster decrease of the HOMO-LUMO gap with chain extension due to the combined effects of enhanced planarity and lower overall aromatic character of the system. Although the incorporation of two consecutive double bonds in the system leads to a stabilization of the dicationic state, this structural modification does not produce the expected further decrease of the HOMO-LUMO gap at large chain extension. This phenomenon is discussed on the basis of an interplay between aromaticity and bond length alternation. 相似文献
27.
This study deals with a centrifugal partition chromatography developed for the separation of phenolic compounds from Vitis vinifera. EtOAc grape seed extracts were separated using the solvent system hexane-ethyl acetate-ethanol-water (1:8:2:7; v/v) in two fractions: one containing about 75% of flavanol monomers (catechin and epicatechin) corresponding to 18% of crude extract and another fraction B-type dimers (22% of crude extract). From the stalk extracts, we could separate stilbenoid compounds (resveratrol and its oligomers; 12% of crude extract) which were eluted in less than 30 min from flavanols (which required a few hours of additional elution). Using the same solvent system but in different ratios (4:5:3:3; v/v), we isolated the trans-resveratrol (7@1000; 90% purity). 相似文献
28.
D.M. De Castro Rizzo E. Bozek S. Cavallaro B. Delaunay J. Delaunay H. Dumont M.G. Saint-Laurent F. Terrasi 《Nuclear Physics A》1984,427(1):151-172
Fusion excitation functions for the systems 12C + 46, 48, 50Ti, 28, 30Si + 30Si and 18O + 44Ca have been determined at energies near and below the Coulomb barrier. Inelastic excitation functions for the targets 48, 50Ti and 44Ca have been also measured in the same energy range. The absolute cross sections were obtained by in-beam γ-ray spectroscopy technique using a rotating target. Fusion cross sections ranging in magnitude from ~ 0.3 mb to ~ 1300 mb were determined with an accuracy of 10–20%. The fusion excitation functions are analysed in the frame of a semiclassical barrier-penetration model. From the analysis, the height, the radius and the curvature of the fusion barrier for the different systems are extracted. The fusion cross sections are compared with the calculations performed using different heavy-ion potentials. The enhancement of the cross sections at sub-Coulomb energies can be reproduced with a one-dimensional barrier-penetration model taking into account the zero-point motion of the surface of the reaction partners. The fusion cross section of the system 18O + 44Ca is well reproduced by quantum-mechanical calculations, introducing a new degree of freedom taking into account the formation of a neck during the fusion process. 相似文献
29.
High spin states of 57Co have been studied via prompt γ-ray spectroscopy in the reactions 48Ti(12C, p2n) and 54Fe(α, p) at 26–48 MeV and 12–24 MeV, respectively. The energies and decay modes of these levels were determined from the analysis of γ-ray singles and γ-γ coincidence spectra, excitation functions, angular distributions and correlations. The relevant lifetimes were measured by the Doppler-shift attenuation method. The new levels established in this work are at 4037, 4814 and 5918 keV with the most probable Jπ assignment of , if and , respectively. The previously known level at 2524 keV was assigned to have . These together with the known (1224 keV) and (1690 keV) levels constitute the yrast states of 57Co. The measured lifetimes of the above six levels are (in order of increasing energies) 0.085±0.030, 0.32±0.10, 0.16±0.06, 0.10?0.07+0.06, 1.5?0.54 and 0.17?0.07+0.08 ps, respectively. Comparisons with some theoretical calculations are presented. 相似文献
30.
M. Pichevar J. Delaunay B. Delaunay H.J. Kim Y. El Masri J. Vervier 《Nuclear Physics A》1976,264(1):132-150
High-spin states in 59Ni have been investigated via the study of in-beam γ-rays following the reactions 50Cr(12C, 2pn)59Ni (26–58 MeV) and 56Fe(α, n)59Ni (10, 15, 22.5 MeV). The spins of previously known levels have been confirmed or determined for the first time, in particular for those at . New states have been established and their spin determined, at . The resulting 59Ni decay scheme is discussed in the framework of nuclear models. 相似文献