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Perez C Espinola CG Foces-Foces C Nunez-Coello P Carrasco H Martin JD 《Organic letters》2000,2(9):1185-1188
[formula: see text] In this contribution, we describe the ability of compound (+/-)-1b and six molecules of water to form in solid-state hexameric aggregates, which self-assemble to give hollow tubular structures. Single-crystal X-ray analysis shows that these tubes are open-ended, with irregular shape and internal van der Waals pore diameter between 6 and 9 A. In addition, transmembrane sodium transport activity was also assessed for (+/-)-1b using dynamic Na(+)-NMR technique. 相似文献
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R.L. Mascorro Alquicira J.L. Casas Espinola E. Velázquez Lozada G. Polupan L. Shcherbyna 《Superlattices and Microstructures》2012
The photoluminescence (PL), its temperature dependence and X ray diffraction (XRD) have been studied in the symmetric In0.15Ga0.85As/GaAs quantum wells (QWs) with embedded InAs quantum dots (QDs), obtained with the variation of QD growth temperatures (470–535 °C). The increase of QD growth temperatures is accompanied by the enlargement of QD lateral sizes (from 12 up to 28 nm) and by the shift non monotonously of PL peak positions. The fitting procedure has been applied for the analysis of the temperature dependence of PL peaks. The obtained fitting parameters testify that in studied QD structures the process of In/Ga interdiffusion between QDs and capping/buffer layers takes place partially. However this process cannot explain the difference in PL peak positions. 相似文献
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M. Dybiec S. Ostapenko J.L. Casas Espinola K.J. Malloy 《Applied Surface Science》2006,252(15):5542-5545
The photoluminescence spectra of InAs quantum dots (QDs) embedded into four types of InxGa1−xAs/GaAs (x = 0.10, 0.15, 0.20 and 0.25) multi quantum well MBE structures have been investigated at 300 K in dependence on the QD position on the wafer. PL mapping was performed with 325 nm HeCd laser (35 mW) focused down to 200 μm (110 W/cm2) as the excitation source. The structures with x = 0.15 In/Ga composition in the InxGa1−xAs capping layer exhibited the maximum photoluminescence intensity. Strong inhomogeneity of the PL intensity is observed by mapping samples with the In/Ga composition of x ≥ 0.20-0.25. The reduction of the PL intensity is accompanied by a gradual “blue” shift of the luminescence maximum at 300 K as follows from the quantum dot PL mapping. The mechanism of this effect has been analyzed. PL peak shifts versus capping layer composition are discussed as well. 相似文献
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The functional Ito formula, in the form df() = f( + d ) f(),is formulated and proved in the context of a Lie algebra L associatedwith a quantum (non-commutative) stochastic calculus. Here fis an element of the universal enveloping algebra U of L, andf() + d() f() is given a meaning using the coproductstructure of U even though the individual terms of this expressionhave no meaning. The Ito formula is equivalent to a chaoticexpansion formula for f() which is found explicitly. 1991 MathematicsSubject Classification: primary 81S25; secondary 60H05; tertiary18B25. 相似文献
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We report spontaneous Raman scattering at 1550 nm in ultrasmall silicon-on-insulator (SOI) strip waveguides of 0.098-microm2 cross-sectional area. The submicrometer-scale dimensions provide tight optical confinement and, hence, highly efficient Raman scattering with milliwatt-level cw pump powers. The prospect of Raman amplification in such a deeply scaled-down waveguide device in the presence of various loss mechanisms, particularly free-carrier loss that arises from two-photon absorption, is discussed, and the feasibility of high-gain SOI-based fully integrated optical amplifiers is shown. 相似文献
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L. E. Espinola López J. J. Soares Neto 《International Journal of Theoretical Physics》2000,39(4):1129-1145
We propose a hyperspherical coordinate system for the three-body problem. Theclassical and quantum Hamiltonians are derived as well as the classical equationsof motion. General expressions for distances between the particles inhyperspherical coordinates are obtained. Finally, potential energy plots for thewater molecule are constructed. 相似文献
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Bobeldijk I Bouwhuis M Ireland DG de Jager CW Jans E de Jonge N Kasdorp WJ Konijn J Lapikás L van Leeuwe JJ van der Meer RL Nooren GJ Passchier E Schroevers M van der Steenhoven G Steijger JJ Theunissen JA van Uden MA de Vries H de Vries R de Witt Huberts PK Blok HP van den Brink HB Dodge GE Harakeh MN Hesselink WH Kalantar-Nayestanaki N Pellegrino A Spaltro CM Templon JA Hicks RS Kelly JJ Marchand C 《Physical review letters》1994,73(20):2684-2687
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Maria G. da Fonseca Ramon K.S. Almeida Luiza N.H. Arakaki Jos G.P. Espinola Claudio Airoldi 《Colloids and surfaces. A, Physicochemical and engineering aspects》2006,280(1-3):39-44
Two vermiculite hybrids containing aliphatic amines intercalated were synthesized. The amount of guest molecules intercalated resulted in 0.60 and 0.52 mmol g−1 for pyperidine and pyperazine, respectively, which reflect the effectiveness of such kind of reactions. The processes were confirmed by elemental analysis and infrared spectroscopy. X-ray diffraction patterns suggested that the original crystallinity of matrix was maintained, however, the intercalation process is associated with the conformation of the guest molecule and the presence of the compensate cation inside the interlayer cavity. The intercalated inorganic hosts adsorb divalent lead, nickel, copper and cobalt cations, more effectively at basic pH value, from aqueous solution, which content of adsorption is higher than the precursor native vermiculite. 相似文献