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61.
Bernard Lavielle Bertrand Thomas Eric Gilabert Gregory Canchel Denis Horlait Sylvain Topin Fabien Pointurier Christophe Moulin 《Journal of mass spectrometry : JMS》2016,51(10):908-913
A double focusing sector field mass filter used in Nier–Johnson geometry has been built in order to perform Kr isotope enrichment for 81Kr and 85Kr isotopes. The principle consists in implanting Kr+ ions accelerated at 7 keV in Al foils after separation using the magnetic sector. A specific ion source has been designed capable of generating high Kr+ ion beams (>0.5 μA) to transfer into the collecting Al foils in 3 to 5 h significant fractions of large Kr samples (1015 to 1016 atoms) initially introduced in the instrument. Implanted Kr isotopes can be further selectively released from the Al foil by surface ablation using an infrared laser beam. Implantation yields and enrichment factors are measured using a conventional mass spectrometer. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
62.
Dr. David Martin Dr. Nicolas Lassauque Florian Steinmann Gerald Manuel Prof. Guy Bertrand 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(44):14895-14901
Experimental and computational investigations of anti‐Bredt amidinium salts are presented. Calculations show that the pyramidalization of an amino group can significantly destabilize the formal carbocation center of amidiniums, due to the decreased π donation. In some cases, the unfavorable ‐I effect of nitrogen surpasses its beneficial +M effect, and amidiniums become less stable than iminiums. It is shown that although 1‐aza‐3‐azonia[3.3.1]bicyclo‐non‐2‐enes can be isolated, they feature a nonclassical reactivity, which is more typical for iminium than amidinium salts, such as pronounced electrophilicity and azomethineylide instead of carbene formation. 相似文献
63.
A. Wnuk M. Kaczkan R. Piramidowicz R. Mahiou G. Bertrand M.-F. Joubert 《辐射效应与固体损伤》2013,168(1-6):469-473
The dynamics of up-conversion, green emission under excitation at different infra-red wavelength in Ho3? doped ZBLAN fiber is reported. Under infrared, 890 nm quasi cw pumping the complicated temporal behavior of the up-conversion signal is strongly influenced by the intermediate 5I5 state cross relaxation. The mechanisms of the observed up-conversion processes are proposed and the time evolution of the 5S2 population is described by the rate equation model. Parameters of the model are determined and numerical simulations of the excited state dynamics are performed. 相似文献
64.
Literature methods for synthesis of small and medium size monocyclic hydroxamic acids are reviewed, covering the last 30 years. 相似文献
65.
N‐(2‐Ethylhexyl)carbazole: A New Fluorophore Highly Suitable as a Monomolecular Liquid Scintillator 下载免费PDF全文
Eva Montbarbon Dr. Fabien Sguerra Dr. Guillaume H. V. Bertrand Élodie Magnier Dr. Romain Coulon Dr. Robert B. Pansu Dr. Matthieu Hamel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(34):12074-12080
The synthesis, photophysical properties, and applications in scintillation counting of N‐(2‐ethylhexyl)carbazole (EHCz) are reported. This molecule displays all of the required characteristics for an efficient liquid scintillator (emission wavelength, scintillation yield), and can be used without any extra fluorophores. Thus, its scintillation properties are discussed, as well as its fast neutron/gamma discrimination. For the latter application, the material is compared with the traditional liquid scintillator BC‐501 A, and other liquid fluorescent molecules classically used as scintillation solvents, such as xylene, pseudocumene (PC), linear alkylbenzenes (LAB), diisopropylnaphthalene (DIN), 1‐methylnaphthalene (1‐MeNapht), and 4‐isopropylbiphenyl (iPrBiph). For the first time, an excimeric form of a molecule has been advantageously used in scintillation counting. A moderate discrimination between fast neutrons and gamma rays was observed in bulk EHCz, with an apparent neutron/gamma discrimination potential half of that of BC‐501 A. 相似文献
66.
Ahlem Bouhlel Christophe Curti Michèle P. Bertrand Patrice Vanelle 《Tetrahedron》2012,68(18):3596-3604
An easily reproducible protocol allowing inter- or intramolecular spirocyclization on β-dicarbonyl structures is described. This methodology could afford a wide variety of spirocyclic pharmacophores. As examples, highly substituted spirobenzophenanthridin-6(5H)-ones and spirolactones were synthesized. These scaffolds could be used for the design of many compounds exhibiting biological activities. 相似文献
67.
Bertrand Chauvineau 《General Relativity and Gravitation》2002,34(11):1855-1864
We show that the general relativity theory equation, in presence of pressureless matter (dust) in irrotational motion, can be recovered from a scalar-tensor like variational approach. In this approach, the kinetic energy, , of a dynamical scalar field , couples directly to gravity. The lagrangian, exempt of explicit matter term, is varied in the framework of the first order formalism, and a conformal transformation, restoring riemannian geometry, is made. In this approach, it turns out that a non-empty spacetime is necessarily four-dimensional. 相似文献
68.
Gehanne S Cecconi D Carboni L Righetti PG Domenici E Hamdan M 《Rapid communications in mass spectrometry : RCM》2002,16(17):1692-1698
We describe a simple approach for the relative quantification of individual proteins within a mixture. The method is based on the differential labelling of the mixtures by use of a commercially available acrylamide and deuterium-labelled [2,3,3'-d(3)]-acrylamide to alkylate proteins prior to two-dimensional (2-D) gel electrophoresis. The tryptic digests of the separated proteins were subjected to reflector matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) analysis and the relative peak heights of cysteine-containing peptides were used to quantify their precursor proteins. This approach was tested for the relative quantification of proteins within an artificial mixture of standard proteins and for proteins observed in a 2-D map of rat serum. A good correlation was found between the measured ratios derived from MALDI-TOF data and those theoretically calculated prior to 2-D analysis via known mixing ratios of the two alkylating reagents. The described procedure has proved to be effective for comparative measurements of protein abundances within the investigated mixtures. 相似文献
69.
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