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811.
Rangan S Bournel F Gallet JJ Kubsky S Le Guen K Dufour G Rochet F Sirotti F Piaszenski G Funke R Kneppe M Köhler U 《The journal of physical chemistry. B》2005,109(26):12899-12908
Using a combination of local -- scanning tunneling microscopy -- and spatially integrated, but chemically sensitive probes -- X-ray photoelectron spectroscopy and near edge X-ray absorption fine structure spectroscopy -- we have examined how 3-butenenitrile reacts with the Si(001)-2 x 1 surface at room temperature. Electron spectroscopies indicate three different nitrogen chemical bonds: a Si-C=N-Si bond, a C=C=N cumulative double bond, and a CN moiety datively bonded to a silicon atom. All molecular imprints detected by scanning tunneling microscopy (STM) involve two adjacent silicon dimers in the same row. The three geometries we propose -- a double di-sigma bonding via the CN and the C=C, a cumulative double bond formation associated with alphaC-H bond dissociation, and a di-sigma vinyl bonding plus a CN datively bonded to a silicon atom -- are all compatible with electron spectroscopies and data. Real-time Auger yield kinetic measurements show that the double di-sigma bonding geometry is unstable when exposed to a continuous flux of 3-butenenitrile molecules, as the Si-C=N-Si unit transforms into a CN moiety. A model is proposed to explain this observation. 相似文献
812.
The Lie group SU(2) endowed with its canonical subriemannian structure appears as a three-dimensional model of a positively curved subelliptic space. The goal of this work is to study the subelliptic heat kernel on it and some related functional inequalities. 相似文献
813.
We establish a Jacobian estimate in the context of Ginzburg–Landau theory, which was conjectured in a recent work of Bourgain, Brezis and Mironescu. To cite this article: F. Bethuel et al., C. R. Acad. Sci. Paris, Ser. I 337 (2003). 相似文献
814.
This Note proposes a new methodology for function classification with Support Vector Machine (SVM). Rather than relying on projection on a truncated Hilbert basis as in our previous work, we use an implicit spline interpolation that allows us to compute SVM on the derivatives of the studied functions. To that end, we propose a kernel defined directly on the discretizations of the observed functions. We show that this method is universally consistent. To cite this article: N. Villa, F. Rossi, C. R. Acad. Sci. Paris, Ser. I 343 (2006). 相似文献
815.
Fabrice Colin Marlène Frigon 《NoDEA : Nonlinear Differential Equations and Applications》2006,13(3):369-384
We establish the existence of a nontrivial solution to systems of coupled Poisson equations with critical growth in unbounded
domains. The proofs rely on a generalized linking theorem due to Krysewski and Szulkin, and on a concentration-compactness
argument since the Palais-Smale condition fails at all critical levels. 相似文献
816.
The study deals with a rotor–stator contact inducing vibration in rotating machinery. A numerical rotor–stator system, including a non-linear bearing with Hertz contact and clearance is considered. To determine the non-linear responses of this system, non-linear dynamic equations can be integrated numerically. However, this procedure is both time consuming and costly to perform. The aim of this Note is to apply the Alternate Frequency/Time Method and the ‘path following continuation’ in order to obtain the non-linear responses to this problem. Then the orbits of rotor and stator responses at various speeds are investigated. To cite this article: J.-J. Sinou, F. Thouverez, C. R. Mecanique 332 (2004). 相似文献
817.
Sophie Martel Frédéric Begnaud William Schuler Fabrice Gillerat Nils Oberhauser Alessandra Nurisso Pierre-Alain Carrupt 《Analytica chimica acta》2016
Lipophilicity is of crucial importance in many fields including pharmaceutical, environmental, cosmetic and food industries. Whereas different experimental strategies have been developed for rapid lipophilicity determination of new chemical entities, log P determination of highly lipophilic compounds is always challenging. In this study, three published chromatographic methods have been compared on a series of phenylalkanoic acids including the pro-perfume Haloscent®D (HD-C12). Different log P values were obtained depending on the chromatographic method used for log P estimation. Molecular modelling suggested that log P variations may be due to the chromatographic conditions applied (isocratic or gradient mode, ratio methanol/water in the mobile phase), responsible of specific conformations of the molecule in solution. Thus, for flexible compounds, published methods have to be used with caution and considered as a good tool to estimate a log P range, depending on the molecular conformational state. 相似文献
818.
A method allowing the identification of parameters that govern constitutive equations of materials is proposed in this Note. These parameters are identified from heterogeneous strain fields. The method is direct so that iterative calculations based on finite element model updating are avoided. To cite this article: M. Grédiac et al., C. R. Mecanique 330 (2002) 107–112. 相似文献
819.
Influence of Electronic Effects on the Reactivity of Triazolylidene‐Boryl Radicals: Consequences for the use of N‐Heterocyclic Carbene Boranes in Organic and Polymer Synthesis 下载免费PDF全文
Sofia Telitel Anne‐Laure Vallet Darrin M. Flanigan Dr. Bernadette Graff Dr. Fabrice Morlet‐Savary Prof. Tomislav Rovis Prof. Jacques Lalevée Dr. Emmanuel Lacôte 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(39):13772-13777
A small library of triazolylidene‐boranes that differ only in the nature of the aryl group on the external nitrogen atom was prepared. Their reactivity as hydrogen‐atom donors, as well as that of the corresponding N‐heterocyclic carbene (NHC)‐boryl radicals toward methyl acrylate and oxygen, was investigated by laser flash photolysis, molecular orbital calculations, and ESR spin‐trapping experiments, and benchmarked relative to the already known dimethyltriazolylidene‐borane. The new NHC‐boranes were also used as co‐initiators for the Type I photopolymerization of acrylates. This allowed a structure–reactivity relationship with regard to the substitution pattern of the NHC to be established and the role of electronic effects in the reactivity of NHC‐boryl radicals to be probed. Although their rate of addition to methyl acrylate depends on their electronegativity, the radicals are all nucleophilic and good initiators for photopolymerization reactions. 相似文献
820.
Baptiste Picard Boris Gouilleux Dr. Thomas Lebleu Dr. Jacques Maddaluno Prof. Isabelle Chataigner Dr. Maël Penhoat Prof. François-Xavier Felpin Dr. Patrick Giraudeau Dr. Julien Legros 《Angewandte Chemie (International ed. in English)》2017,56(26):7568-7572
The fast and effective neutralization of the mustard-gas simulant 2-chloroethyl ethyl sulfide (CEES) using a simple and portable continuous flow device is reported. Neutralization takes place through a fully selective sulfoxidation by a stable source of hydrogen peroxide (alcoholic solution of urea–H2O2 adduct/MeSO3H freshly prepared). The reaction progress can be monitored with an in-line benchtop NMR spectrometer, allowing a real-time adjustment of reaction conditions. Inherent features of millireactors, that is, perfect control of mixing, heat and reaction time, allowed the neutralization of 25 g of pure CEES within 46 minutes in a 21.5 mL millireactor (tR=3.9 minutes). This device, which relies on affordable and nontoxic reagents, fits into a suitcase, and can be deployed by police/military forces directly on the attack site. 相似文献