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131.
Sabelle S Renard PY Pecorella K de Suzzoni-Dézard S Créminon C Grassi J Mioskowski C 《Journal of the American Chemical Society》2002,124(17):4874-4880
Acetylcholinesterase is one of the most widely used and studied enzymes. Not only does this enzyme regulate neurotransmission (and thus play a key role in neurodegenerative processes) but it is also a prime target for pest control agents and warfare agents. Above all, due to its particularly high turnover rate, acetylcholinesterase is among the most efficient reporter enzymes yet described (for use as enzymatic tracer in immunoassays, for instance). However, its activity is detected through a colorimetric reagent, the Ellman reagent, which displays low detection limits and is often subject to background perturbations. In the course of our search for a more sensitive detection assay, we describe here a first-generation 1,2-dioxetane chemiluminescent probe, based on chemically induced electron exchange luminescence, which has an approximately 10 times lower detection limit than the Ellman colorimetric assay (2.5 x 10(-19) mol for Electrophorus electricus AChE in its tetrameric form). 相似文献
132.
B. Vinter J. L. Reverchon G. Marre M. Carras C. Renard X. Marcadet V. Berger 《Comptes Rendus Physique》2003,4(10):1103-1108
A study of the optimization of the detectivity of a mid infrared double heterostructure photovoltaic detector is proposed. Simple approximate analytic expressions for the dark current are compared with full numerical calculations, and give physical insight on the mechanisms dominating the dark current. The analysis is performed step by step, from a simple p–n junction to the full double heterostructure. The influence of temperature, barrier band gap energy in a double heterostructure, doping density in the active region, on diffusion and generation–recombination mechanisms is analyzed. It is shown how the performances of a double heterostructure photovoltaic detector can be improved by a controlled doping the active region. Nevertheless, its development is still limited by the difficulties occurring during device processing. For example, the use of dry etching for the processing of InAs0.91Sb0.09 p–i–n photovoltaic detectors induces a strong leakage current along the mesa edge. In this letter, we show an improvement of the R0A characteristic by several orders of magnitude at low temperature by using an Ion Beam Etching (IBE) followed by a wet chemical etching. This optimized and reliable device processing allows us to demonstrate that the detector performance is actually limited by the diffusion current of holes. Finally, we discuss the ability of an n-type barrier made of InAs/AlSb super-lattice to avoid hole diffusion and to improve the R0A characteristic of these detectors. To cite this article: B. Vinter et al., C. R. Physique 4 (2003). 相似文献
133.
Traoré T Clavé G Delacour L Kotera N Renard PY Romieu A Berthault P Boutin C Tassali N Rousseau B 《Chemical communications (Cambridge, England)》2011,47(34):9702-9704
Cryptophane-111 is one of the best candidates for (129)Xe MRI-based applications. Herein, we report the first metal-free and water-soluble cryptophane-111 core which involves an efficient and unusual post-synthetic sulfonation procedure. 相似文献
134.
G. Montes-Hernandez A. Fernndez-Martínez L. Charlet D. Tisserand F. Renard 《Journal of Crystal Growth》2008,310(11):2946-2953
The hydrothermal carbonation of calcium hydroxide (Ca(OH)2) at high pressure of CO2 (initial PCO2=55 bar) and moderate to high temperature (30 and 90 °C) was used to synthesize fine particles of calcite. This method allows a high carbonation efficiency (about 95% of Ca(OH)2–CaCO3 conversion), a significant production rate (48 kg/m3 h) and high purity of product (about 96%). However, the various initial physicochemical conditions have a strong influence on the crystal size and surface area of the synthesized calcite crystals. The present study is focused on the estimation of the textural properties of synthesized calcite (morphology, specific surface area, average particle size, particle size distribution and particle size evolution with reaction time), using Rietveld refinements of X-ray diffraction (XRD) spectra, Brunauer–Emmett–Teller (BET) measurements, and scanning electron microscope (SEM) and transmission electron microscope (TEM) observations. This study demonstrate that the pressure, the temperature and the dissolved quantity of CO2 have a significant effect on the average particle size, specific surface area, initial rate of precipitation, and on the morphology of calcium carbonate crystals. In contrast, these PTx conditions used herein have an insignificant effect on the carbonation efficiency of Ca(OH)2.
Finally, the results presented here demonstrate that nano-calcite crystals with high specific surface area (SBET=6–10 m2/g) can be produced, with a high potential for industrial applications such as adsorbents and/or filler in papermaking industry. 相似文献
135.
Sacré PY Deconinck E Daszykowski M Courselle P Vancauwenberghe R Chiap P Crommen J De Beer JO 《Analytica chimica acta》2011,(2):224-231
Most of the counterfeit medicines are manufactured in non good manufacturing practices (GMP) conditions by uncontrolled or street laboratories. Their chemical composition and purity of raw materials may, therefore, change in the course of time. The public health problem of counterfeit drugs is mostly due to this qualitative and quantitative variability in their formulation and impurity profiles.In this study, impurity profiles were treated like fingerprints representing the quality of the samples. A total of 73 samples of counterfeit and imitations of Viagra® and 44 samples of counterfeit and imitations of Cialis® were analysed on a HPLC-UV system. A clear distinction has been obtained between genuine and illegal tablets by the mean of a discriminant partial least squares analysis of the log transformed chromatograms. Following exploratory analysis of the data, two classification algorithms were applied and compared. In our study, the k-nearest neighbour classifier offered the best performance in terms of correct classification rate obtained with cross-validation and during external validation. For Viagra®, both cross-validation and external validation sets returned a 100% correct classification rate. For Cialis® 92.3% and 100% correct classification rates were obtained from cross-validation and external validation, respectively. 相似文献
136.
The design and synthesis of novel water-soluble far-red emitting phenol-based fluorophores derived from 7-hydroxycoumarin are described. These hemicyanine-coumarin hybrids display promising spectroscopic features such as large apparent Stokes shift (ranging from 60 to 140 nm) and fluorescence emission maxima between 620 and 720 nm in physiological conditions. Their utility was then illustrated by the preparation of an original fluorogenic probe of penicillin G acylase (PGA) whose fluorescence is unveiled through an enzyme-initiated domino reaction. 相似文献
137.
F. M. Renard 《Zeitschrift fur Physik C Particles and Fields》1984,24(3):385-393
We review, update and propose tests of a possible substructure of leptons, quarks andW ±,Z bosons for the next generation ofe + e ? colliders. We successively consider the three following domains of physics: at theZ peak, out of theZ peak and in the high energy range. 相似文献
138.
Houari Boumediène Khenous Patrick Laborde Yves Renard 《Comptes Rendus Mathematique》2006,342(10):791-796
The purpose of this Note is to compare two approaches for the discretization of elastodynamic contact problems. First, we introduce an energy conserving method based on a standard midpoint scheme and a contact condition expressed in terms of velocity. The second approach consists in considering an equivalent distribution of the body mass so that the nodes on the contact boundary have no inertia. We prove that this method leads to an energy conservation for the space semi-discretized elastodynamic contact problem. Finally, some numerical results are presented in the two dimensional case. To cite this article: H.B. Khenous et al., C. R. Acad. Sci. Paris, Ser. I 342 (2006). 相似文献
139.
We first show that the enhancement observed by Cello can neither be explained by real or virtual μ1 production through μ1μγ or μ1μZ couplings nor by μμγγ or μμγZ contact terms, when one imposes the usual constraints from . We then propose an explanation using an eeμμ1 contact term which is less constrained. In addition to this leads to a direct decay . Generalized to other types of fermion pairs we have here an interesting source of multifermion anomalous events. 相似文献
140.
Several fixed point strategies and Uzawa algorithms (for classical and augmented Lagrangian formulations) are presented to solve the unilateral contact problem with Coulomb friction. These methods are analysed, without introducing any regularization, and a theoretical comparison is performed. Thanks to a formalism coming from convex analysis, some new fixed point strategies are presented and compared with known methods. The analysis is first performed on continuous Tresca problem and then on the finite dimensional Coulomb problem derived from an arbitrary finite element method. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献