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121.
Pedrosa MA Silva C Hidalgo C Carreras BA Orozco RO Carralero D;TJ-II team 《Physical review letters》2008,100(21):215003
Long-distance coupling between edge parameters' fluctuations has been investigated in the TJ-II stellarator. Results show long-range correlations in potential fluctuations, which are amplified by the development of radial electric fields during transitions to improved-confinement regimes, whereas there is no correlation between ion saturation current signals. These experimental findings suggest the importance of long-range correlations as a new fingerprint of the plasma behavior during the development of edge shear flows and the key role of electric fields to amplify them. 相似文献
122.
Murilo F. Cabral Valber A. Pedrosa Sergio A.S. Machado 《Applied Surface Science》2008,254(17):5612-5617
The deposition and characterization of Se films doped with Pb underpotentially deposited (UPD) ad-atoms was studied in this work. The employed experimental techniques were cyclic voltammetry, chronoamperometry, electrochemical impedance spectroscopy, UV-vis spectroscopy and atomic force microscopy. The initial deposition of Se film by chronoamperometry yielded a thin film composed of approximately 700 layers. The Pb UPD on Se was achieved by chronoamperometry in a potential value previously determined in voltammetric experiments. This deposition yielded a deposition charge of approximately 7.5% of the total one. The film resistance altered from 320 Ω cm−2 for Se to 65 Ω cm−2 for the Se/Pb one. Flat band potential values and number of acceptors and donors were also calculated for both films and the values obtained were +0.95 and −0.51 V for Se and Se/Pb, respectively. The Se coating presented 1.2 × 1017 cm−3 acceptors while the Se/Pb one presented 3.2 × 1017 cm−3 donors. The band gap values for both films were 2.4 eV and 1.9 eV, correspondingly. 相似文献
123.
124.
Chiral 3-acryloyl-2-vinyl-substituted 1,3-perhydrobenzoxazines derived from (-)-8-aminomenthol participate in an ene reaction leading to 3,4-disubstituted pyrrolidinone derivates with excellent diastereoselectivity. The cycloadducts were transformed into enantiopure 3,4-disubstituted pyrrolidines after elimination of the chiral adjuvant. 相似文献
125.
Anne M. Garrido Pedrosa Marcelo J. B. Souza Joana D. G. Fernandes Dulce M. A. Melo Antonio S. Araujo 《Reaction Kinetics and Catalysis Letters》2003,79(2):391-396
The present study reports the catalytic behavior of Co3O4-CeO2 in the oxidation of n-heptane. The results obtained showed that the catalyst give good activity in n-heptane oxidation with high selectivity to carbon dioxide.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
126.
Hidalgo C Gonçalves B Silva C Pedrosa MA Erents K Hron M Matthews GF 《Physical review letters》2003,91(6):065001
The dynamical coupling between turbulent transport and parallel flows has been investigated in the plasma boundary region of the Joint European Torus tokamak. Experimental results show that there is a dynamical relationship between transport and parallel flows. As the size of transport events increases, parallel flows also increase. These results show that turbulent transport can drive parallel flows in the plasma boundary of fusion plasmas. This new type of measurement is an important element to unravel the overall picture connecting radial transport and flows in fusion plasmas. 相似文献
127.
S. Aznarez M. A. Postigo G. C. Pedrosa I. L. Acevedo M. Katz 《Journal of solution chemistry》1998,27(10):949-964
Excess molar volumes and excess refractive indexes of the n-hexanol + ethanenitrile + dichloromethane system and the three corresponding binary mixtures have been determined at 25°C, by measuring densities and refractive indexes. Different expressions exist in the literature to predict these excess properties from binary data. The empirical correlation of Cibulka is shown to be the best in this system. An estimation of excess molar volumes is also evaluated using a modified Heller equation, which depends on the refractive indexes of the mixtures. Comparison of the predictions by different methods with the experimental values of the physical properties has been made. 相似文献
128.
Densities and viscosities were determined for the n-pentanol-cumene-1,4-dioxane system at 298.15 K. From the experimental results, molar excess volumes and excess viscosities were calculated. Different expressions exist in the literature to predict these excess properties from the binary data. The empirical correlation of Cibulka is shown to be the best for this system. 相似文献
129.
G. M. Batanov A. E. Petrov K. A. Sarksyan N. N. Skvortsova O. I. Fedyanin N. K. Kharchev Yu. V. Khol’nov S. V. Shchepetov C. Hidalgo M. Pedrosa B. van Milligen E. Sanchez 《JETP Letters》1998,67(9):662-667
Results are reported from an experimental study of the characteristics of the turbulent edge plasma in the L-2M stellarator.
Extended coherent structures are observed to form in the poloidal direction. The poloidal coherence length of the fluctuations
reaches 20 cm. The coherence of the fluctuations depends appreciably on the poloidal azimuth and is maximum along the outer
edge, as is natural for unstable modes in a toroidal plasma.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 9, 634–639 (10 May 1998) 相似文献
130.
This paper describes about an automated on-line enrichment method for the simultaneous determination of seven β-blockers in river water using a short liquid chromatography column for preconcentration coupled with LC-DAD. The method performs the preconcentration of 30 mL of river water samples (5% organic modifier) using a 50 mm × 4.6 mm C18 column for enrichment and a 150 mm × 4.6 mm C18 column for separation, allowing the determination of β-blockers at trace levels in river water. The analytical procedure was developed by optimizing the breakthrough parameters (flow rate, time of preconcentration and percentage of organic modifier added to the sample) in order to achieve the maximum sensitivity, and by optimizing the mobile phase (composition and flow rate) to get adequate separation of the components in a reasonable analysis time. Under the optimized conditions, the method was validated with respect to linearity, precision, limits of detection, limits of quantification and accuracy. Detection and quantitation limits ranged between 0.1 and 3.1 and between 1.0 and 5.0 ng mL−1, respectively, whereas the RSD on inter-day precision was below 8%.To cope with the matrix effect in the determination of these drugs in river water samples, the standard addition methodology was successfully applied. Recoveries ranging from 81 to 115% proved the accuracy of the methodology proposed in this work. 相似文献