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991.
Lucian-Cristian Pop Nadia Katir Annie Castel Luminita Silaghi-Dumitrescu Fabien Delpech Ioan Silaghi-Dumitrescu Heinz Gornitzka Desmond MacLeod-Carey Nathalie Saffon 《Journal of organometallic chemistry》2009,694(9-10):1562-1566
New phosphenium cations stabilized by bidentate monoanionic N-isopropyl-2-(isopropylamino)troponiminate or 2-(isopropylamino)troponate units have been synthesized. These complexes were characterized by 31P, 1H and 13C NMR spectroscopies, and the molecular structures were determined by X-ray crystallography. These data indicate the formation of N,N′- and N,O-chelate derivatives having three-coordinate phosphorous atoms included in planar heterobicycles. Moreover, computational studies support the presence of high delocalization of the positive charge into the π-conjugated carbon backbone and of the high-lying phosphorus lone-pair orbital. 相似文献
992.
This experimental study investigates the retention of bacteria by porous membranes. The transfer of bacteria larger than the nominal pore size of microfiltration track-etched membranes has been studied for several kinds of bacterial strains. This unexpected transfer does not correlate to the hydrophobicity, neither to the surface charge of the microorganism, as suggested in previous reports. We conclude that, in our conditions, the kind of bacteria (Gram-positive or Gram-negative) is finally the most important parameter. As the distinction between those two types of bacteria is related to the cell-wall structure, we provide an experimental evidence, via the action of an antibiotic, that the cell-wall flexibility triggers the transfer of the bacteria through artificial membranes, when the pores are smaller in size than the cell. 相似文献
993.
Given , the Fox–Kleitman conjecture from 2006 states that there exists a nonzero integer such that the -variable linear Diophantine equation is -regular. This is best possible, since Fox and Kleitman showed that for all , this equation is not -regular. While the conjecture has recently been settled for all , here we focus on the case and determine the degree of regularity of the corresponding equation for all . In particular, this independently confirms the conjecture for . We also briefly discuss the case . 相似文献
994.
Bart Beulen Anna Catharina Verkaik Nathalie Bijnens Marcel Rutten Frans van de Vosse 《Experiments in fluids》2010,49(6):1219-1229
A novel axial velocity profile integration method, obtained from ultrasonic perpendicular velocimetry, for flow estimation in curved tubes was validated. In an experimental set-up, physiologically relevant curved geometries and flows were considered. Axial velocity profile measurements were taken by applying particle imaging velocimetry-based methods to ultrasound data acquired by means of a linear array transducer positioned perpendicular to the axial velocity component. Comparison of the assessed asymmetric velocity profiles to computational fluid dynamics calculations showed excellent agreement. Subsequently, the recently introduced cos θ-integration method for flow estimation was compared to the presently applied Poiseuille and Womersley models. The average deviation between the cos θ-integration-based unsteady flow estimate and the reference flow was about 5%, compared to an average deviation of 20% for both the Poiseuille and Womersley approximation. Additionally, the effect of off-centre measurement was analysed for the three models. It was found that only for the cos θ-integration method, an accurate flow estimation is feasible, even when it is measured off centre. 相似文献
995.
996.
We present what is to our knowledge a new method for measuring the relative piston between two independent beams separated by a physical gap, typical of petawatt facilities. The feasibility of this measurement, based on quadriwave lateral shearing interferometry, has been demonstrated experimentally: piston has been measured with accuracy and sensitivity better than 50 nm. 相似文献
997.
In this Note we prove an a priori estimate and the existence of a solution for a class of nonlinear elliptic problems whose model is , when and for some suitable m. The main interest of the result lies in the a priori estimate, the complete proof of which is given in the Note. To cite this article: N. Grenon et al., C. R. Acad. Sci. Paris, Ser. I 342 (2006). 相似文献
998.
Genaro J. Martínez Andrew Adamatzky Juan C. Seck‐Tuoh‐Mora Ramon Alonso‐Sanz 《Complexity》2010,15(6):34-49
Using Rule 126 elementary cellular automaton (ECA), we demonstrate that a chaotic discrete system — when enriched with memory — hence exhibits complex dynamics where such space exploits on an ample universe of periodic patterns induced from original information of the ahistorical system. First, we analyze classic ECA Rule 126 to identify basic characteristics with mean field theory, basins, and de Bruijn diagrams. To derive this complex dynamics, we use a kind of memory on Rule 126; from here interactions between gliders are studied for detecting stationary patterns, glider guns, and simulating specific simple computable functions produced by glider collisions. © 2010 Wiley Periodicals, Inc. Complexity, 2010 相似文献
999.
Nathalie Lamoureux Laurent Gasnot Pascale Desgroux 《Proceedings of the Combustion Institute》2019,37(2):1313-1320
NH is a key short-lived radical involved in the prompt-NO formation. Quantification of NH is thus particularly important for testing the NO kinetic mechanisms. However, quantitative measurements of native NH in hydrocarbon/oxygen/nitrogen flames remain very scarce. Therefore, in this work, the mole fractions of native NH were obtained using a combination of laser-based diagnostics; Laser Induced Fluorescence (LIF) and Cavity Ring-Down Spectroscopy (CRDS). The NH species was probed after exciting the transition R1(6) in the A3Π-X3Σ? (0-0) system at 333.9?nm. The mole fraction profiles of NH were successfully obtained in premixed low-pressure flames of CH4/O2/N2 and C2H2/O2/N2 at two equivalence ratios of 1.00 and 1.25. The estimated detection limit for the NH radical was around 4.5?×?108 molecule cm?3 (i.e. 2 ppb in mole fraction at 1600?K), which is nearly 2 orders of magnitude lower than previous values reported in the literature. These new experimental results were compared with predictions by a recently developed NO model (namely NOMecha2.0). In the case of the CH4 flames, a satisfying agreement between the experiment and model was observed. However, in the case of the C2H2 flames, some discrepancies were observed. Model analysis has highlighted the importance of the HCCO radicals in the NH formation through the HCNO→HNCO→NH2 reactions pathway. Modification of the rate constant values of the reactions C2H2+?O and HCCO?+?O2, which are key reactions for both the acetylene laminar flame speed and the HCCO predictions, has enabled the model to satisfactorily predict the experimental NH and NO profiles also in the C2H2 flames. 相似文献
1000.