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991.
Cecile Baudin Christophe Pean Bruno Pellizzari Andree Gadelle Florence Fauvelle Jean-Claude Debouzy Jean-Pierre Dalbiez Bruno Perly 《Journal of inclusion phenomena and macrocyclic chemistry》2000,38(1-4):287-296
We report on the synthesis,characterization and ionic complexation properties ofhexakis (2-O-acetyl-3,6-anhydro)cyclomaltohexaose and hexakis (2-O-methyl-3,6-anhydro) cyclomaltohexaose usingthin-layer chromatography and Nuclear MagneticResonance spectroscopy. The selectivity towardscations depends on chemical modification of thehydroxyl groups and a very high specificity can beobtained in the case of lead for methylatedderivatives. 相似文献
992.
993.
M. Durante C. Bruno 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,60(1):215-218
Exposure to cosmic radiation is today acknowledged as a major obstacle to
human missions to Mars. In fact, in addition to the poor knowledge on the
late effects of heavy ions in the cosmic rays, simple countermeasures are
apparently not available. Shielding is indeed very problematic in space,
because of mass problems and the high-energy of the cosmic rays, and
radio-protective drugs or dietary supplements are not effective. However,
the simplest countermeasure for reducing radiation risk is to shorten the
duration time, particularly the transit time to Mars, where the dose rate is
higher than on the planet surface. Here we show that using nuclear electric
propulsion (NEP) rockets, the transit time could be substantially reduced to
a point where radiation risk could be considered acceptable even with the
current uncertainty on late effects. 相似文献
994.
995.
Bruno Bassan Claudia Ceci 《Stochastics An International Journal of Probability and Stochastic Processes》2013,85(1-2):55-77
In this paper we show that the solution of a stochastic boundary value problem with additive noise and with a completely nonlinear drift is a Markov field if only if the boundary condition is an initial or a final type condition 相似文献
996.
Bruno Escribano Elena Akhmatskaya Jon I. Mujika 《Central European Journal of Mathematics》2013,11(4):787-799
Generalized Shadow Hybrid Monte Carlo (GSHMC) is a method for molecular simulations that rigorously alternates Monte Carlo sampling from a canonical ensemble with integration of trajectories using Molecular Dynamics (MD). While conventional hybrid Monte Carlo methods completely re-sample particle’s velocities between MD trajectories, our method suggests a partial velocity update procedure which keeps a part of the dynamic information throughout the simulation. We use shadow (modified) Hamiltonians, the asymptotic expansions in powers of the discretization parameter corresponding to timestep, which are conserved by symplectic integrators to higher accuracy than true Hamiltonians. We present the implementation of this method into the highly efficient MD code GROMACS and demonstrate its performance and accuracy on computationally expensive systems like proteins in comparison with the molecular dynamics techniques already available in GROMACS. We take advantage of the state-of-the-art algorithms adopted in the code, leading to an optimal implementation of the method. Our implementation introduces virtually no overhead and can accurately recreate complex biological processes, including rare event dynamics, saving much computational time compared with the conventional simulation methods. 相似文献
997.
Stefan Lautenschlaeger Sebastian Eisermann Michael N. Hofmann Udo Roemer Melanie Pinnisch Andreas Laufer Bruno K. Meyer Holger von Wenckstern Alexander Lajn Florian Schmidt Marius Grundmann Juergen Blaesing Alois Krost 《Journal of Crystal Growth》2010,312(14):2078-2082
We report on the growth of non-polar a-plane ZnO by CVD on r-plane-sapphire-wafers, a-plane GaN-templates and a-plane ZnO single-crystal substrates. Only the homoepitaxial growth approach leads to a Frank–van-der–Merwe growth mode, as shown by atomic force microscopy. The X-ray-diffraction spectra of the homoepitaxial thin films mirror the excellent crystalline quality of the ZnO substrate. The morphological and the structural quality of the homoepitaxial films is comparable to the best results for the growth on c-plane ZnO-substrates. The impurity incorporation, especially of group III elements, seems to be reduced when growing on the non-polar a-plane surface compared to the c-plane films as demonstrated by secondary ion mass spectrometry (SIMS). Optical properties have been investigated using low temperature photoluminescence measurements. We employed capacitance–voltage measurements (C–V) to measure the background carrier density and its profile from substrate/film interface throughout the film to the surface. In thermal admittance spectroscopy (TAS) specific traps could be distinguished, and their thermal activation energies and capture cross sections could be determined. 相似文献
998.
Lidia Caporossi Giovanna Tranfo Enrico Paci Mariangela De Rosa Silvia Capanna Felice Tidei Bruno Papaleo 《Chromatographia》2010,72(3-4):281-287
An LC–DAD method was developed to determine residues of oxamyl on greenhouse workers’ skin. The wipe test was used to obtain samples from hands, forearms, neck and gloves of workers taking cactus cuttings 48 h after pesticide treatment. It was validated in a concentration range 50–5,000 ng mL?1. The results on six workers and ten office employees indicated significant differences particularly in the hand samples. To avoid the overestimation owing to an interfering substance we proceeded to confirm these findings with LC–MS–MS, which found the pesticide only on the surface of the workers’ gloves, proving that there was indeed some UV interference. 相似文献
999.
Cavalcanti Gde A Garrido BC Leal FD Padilha MC de la Torre X Pereira HM de Aquino Neto FR 《Rapid communications in mass spectrometry : RCM》2010,24(22):3297-3302
Trimethylsilylation of anabolic agents and their metabolites is frequently achieved by using the derivatization mixture N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA)/NH(4)I/2-mercaptoethanol. Nevertheless, artifacts were formed when this mixture was employed in the monitoring of exemestane and its main metabolite 17β-hydroxyexemestane prior to GC-MS analysis. These artifacts were identified as the N-methyltrifluoroacetamide (MTFA) and trimethylsiloxyethylmercapto products of the respective trimethylsilyl (TMS) derivatives. Furthermore, artifact formation was evaluated taking the structure (1,4-diene-3-keto-6-exomethylene) of the compounds into account. Although these artifacts are relevant for investigations regarding the derivatization process and may be of interest in many fields, they are detrimental to cope with the requirements of the World Anti-Doping Agency (WADA) in terms of the limits of detection (LODs) required. To overcome this issue, a method using an alternative derivatization was proposed: formation of methyloxime-TMS derivatives through double derivatization using O-methylhydroxylamine/pyridine and MSTFA/TMS imidazole after enzymatic hydrolysis and liquid-liquid extraction. Samples from an excretion study after administration of exemestane to healthy volunteers were analyzed by the proposed method and detection of both exemestane and its main metabolite was possible. This method showed excellent results for both analytes meeting the LODs required for antiestrogenic agents (50 ng/mL) established by WADA. The method was validated for the main metabolite, it was robust and cost-effective for qualitative and quantitative purposes, with LOD and LOQ of 10 ng/mL and 25 ng/mL, respectively. 相似文献
1000.