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221.
222.
Using DFT methods, the electronic properties and the first hyperpolarizabilities of porphyrin‐like porous C24N24 fullerene decorated with (Li3O)n = (1–5) have been systematically investigated. It is found that Li3O molecules can effectively be adsorbed over N4 cavities of C24N24 with high interaction energies. This interaction is found to narrow the HOMO‐LUMO gap and work function values of C24N24. Thus its electronic properties are strongly sensitive to interaction with the Li3O molecules. Indeed, compared with the sole parent C24N24 fullerene, (Li3O)n = (1–5)@C24N24 possess large first hyperpolarizabilities (β0 ). Obviously, the Li3O superalkali chemisorbed over C24N24 fullerene exhibit not only excellent stability but also large first hyperpolarizability. Therefore, they are expected to be potential innovative candidates for excellent electro‐optical materials. 相似文献
223.
Montserrat Corbera Jaume Llibre Ernesto Pérez-Chavela 《Journal of Mathematical Analysis and Applications》2014
In this paper we prove the existence of two new families of spatial stacked central configurations, one consisting of eight equal masses on the vertices of a cube and six equal masses on the vertices of a regular octahedron, and the other one consisting of twenty masses at the vertices of a regular dodecahedron and twelve masses at the vertices of a regular icosahedron. The masses on the two different polyhedra are in general different. We note that the cube and the octahedron, the dodecahedron and the icosahedron are dual regular polyhedra. The tetrahedron is itself dual. There are also spatial stacked central configurations formed by two tetrahedra, one and its dual. 相似文献
224.
Ernesto G. Birgin Emerson V. Castelani André L. M. Martinez J. M. Martínez 《Journal of Optimization Theory and Applications》2011,150(1):142-155
Given an algorithm A for solving some mathematical problem based on the iterative solution of simpler subproblems, an outer trust-region (OTR) modification of A is the result of adding a trust-region constraint to each subproblem. The trust-region size is adaptively updated according
to the behavior of crucial variables. The new subproblems should not be more complex than the original ones, and the convergence
properties of the OTR algorithm should be the same as those of Algorithm A. In the present work, the OTR approach is exploited in connection with the “greediness phenomenon” of nonlinear programming.
Convergence results for an OTR version of an augmented Lagrangian method for nonconvex constrained optimization are proved,
and numerical experiments are presented. 相似文献
225.
Federico Dalmao José R. León Ernesto Mordecki Stéphane Mourareau 《Stochastic Processes and their Applications》2019,129(4):1349-1370
We prove the asymptotic normality of the standardized number of crossings of a centered stationary mixing Gaussian process when both the level and the time horizon go to infinity in such a way that the expected number of crossings also goes to infinity. 相似文献
226.
Ernesto Rezende Souza Ercules E.S. Teotonio Hermi F. Brito 《Journal of luminescence》2010,130(2):283-6601
Red, blue and green emitting rare earth compounds (RE3+=Eu3+, Gd3+ and Tb3+) containing the benzenetricarboxylate ligands (BTC) [hemimellitic (EMA), trimellitic (TLA) and trimesic (TMA)] were synthesized and characterized by elemental analysis, complexometric titration, X-ray diffraction patterns, thermogravimetric analysis and infrared spectroscopy. The complexes presented the following formula: [RE(EMA)(H2O)2], [RE(TLA)(H2O)4] and [RE(TMA)(H2O)6], except for Tb-TMA compound, which was obtained only as anhydrous. Phosphorescence data of Gd3+-(BTC) complexes showed that the triplet states (T) of the BTC3− anions have energy higher than the main emitting states of the Eu3+ (5D0) and Tb3+ (5D4), indicating that BTC ligands can act as intramolecular energy donors for these metal ions. The high values of experimental intensity parameters (Ω2) of Eu3+-(BTC) complexes indicate that the europium ion is in a highly polarizable chemical environment. Based on the luminescence spectra, the energy transfer from the T state of BTC ligands to the excited 5D0 and 5D4 levels of the Eu3+ and Tb3+ ions is discussed. The emission quantum efficiencies (η) of the 5D0 emitting level of the Eu3+ ion have been also determined. In the case of the Tb3+ ion, the photoluminescence data show the high emission intensity of the characteristic transitions 5D4→7FJ (J=0-6), indicating that the BTC ligands are good sensitizers. The RE3+-(BTC) complexes act as efficient light conversion molecular devices (LCMDs) and can be used as tricolor luminescent materials. 相似文献
227.
A chemometric study has been completed in order to investigate the relative contributions and interactions between the many experimental variables involved in SBSE-TD-CGC. The study was centered on data after extraction and analysis of important organophosphorous pesticides from water under different controlled conditions. An enhanced flame photometric detector was used for target compound area response. The seemingly independent operations of extraction with the stir bar followed by thermal transfer of the absorbed compounds to the chromatographic system are usually studied by independent designs for the corresponding blocks of variables. In this work all variables are treated at the same time in a single design to study the interactions and give a more robust model while requiring a lower number of experiments. The relative importance of contributing variables was clearly established and an optimum set of conditions was established for more uniform enrichment in a single analysis for a test mix of compounds with wide ranging polarities. 相似文献
228.
Franco-Prez Luis Prez-Chavela Ernesto 《Nonlinear Analysis: Theory, Methods & Applications》2009,71(11):5131-5143
We develop a regularization for binary collisions in some restricted 3-body problems moving in planar one-dimensional spaces with constant curvature. The main characteristic of the regularization is that it preserves the Hamiltonian structure of the equations and it regularizes all the binary collisions with just one transformation. We apply this global symplectic regularization to the 2-body problem on the unit circle and we show the global dynamics. Also, we tackle the restricted 3-body problem with one fixed center in the unit circle and we give the global dynamics for the case when it has two fixed centers. 相似文献
229.
230.