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1.
Spatial Vector Solitons in Nonlinear Photonic Crystal Fibers 总被引:1,自引:0,他引:1
José R. Salgueiro Yuri S. Kivshar Dmitry E. Pelinovsky Verónica Simón Humberto Michinel 《Studies in Applied Mathematics》2005,115(2):157-171
We study spatial vector solitons in a photonic crystal fiber (PCF) made of a material with the focusing Kerr nonlinearity. We show that such two-component localized nonlinear waves consist of two mutually trapped components confined by the PCF linear and the self-induced nonlinear refractive indices, and they bifurcate from the corresponding scalar solitons. We demonstrate that, in a sharp contrast with an entirely homogeneous nonlinear Kerr medium where both scalar and vector spatial solitons are unstable and may collapse, the periodic structure of PCF can stabilize the otherwise unstable two-dimensional spatial optical solitons. We apply the matrix criterion for stability of these two-parameter solitons, and verify it by direct numerical simulations. 相似文献
2.
Humberto Bustos Rodriguez Dagoberto Oyola Lozano Yebrayl A. Rojas Martínez Germán A. Pérez Alcázar Stefan Flege Adam G. Balogh Louis J. Cabri Michael Tubrett 《Hyperfine Interactions》2007,175(1-3):195-206
X-ray diffraction (XRD), Mössbauer spectrometry (MS), secondary ions mass spectroscopy (SIMS) and laser-ablation microprobe–inductively coupled plasma–mass spectrometry (LAM–ICP–MS) were used to study mineral samples of Colombian auriferous ores collected from the “El Diamante” mine, located in the municipality of Guachavez-Nariño, in Colombia. The samples were prepared as polished thin sections and polished sections. From XRD data, quartz, sphalerite and pyrite were detected and their respective cell parameters were estimated. From MS analyses, pyrite, arsenopyrite and chalcopyrite were identified; their respective hyperfine parameters and respective texture were deduced. Multiple regions of approximately 200 × 200 μm in each sample were analyzed with SIMS; the occurrence of “invisible gold” associated mainly with pyrite and secondarily with arsenopyrite could thus be assigned. It was also found that pyrite is of the arsenious type. Spots from 30 to 40 μm in diameter were analyzed with LAM–ICP–MS for pyrite, arsenopyrite and sphalerite; Au is “homogeneously” distributed inside the structure of the arsenious pyrite and the arsenopyrite (not as inclusions); the chemical composition indicates similarities of this “invisible gold”, forming a solid solution with arsenious pyrite and arsenopyrite. One hundred nineteen and 62 ppm of ‘invisible gold’ was quantified in 21 spots analyzed on pyrite and in 14 spots on arsenopyrite, respectively. 相似文献
3.
Humberto César Chaves Fernandes Arthur Rodrigo Barros da Rocha 《International Journal of Infrared and Millimeter Waves》2003,24(7):1171-1176
The use of photonic materials has been used in the theory of optical waves. The PBG (Photonic Band Gap) theory and material, was developed recently for optical frequencies and can be easily applied to millimeter waves, microwaves and planar antenna frequencies. The presence of photonic materials as substrate in antennas has some good characteristics such as, supression of light spontaneous emission and suppression of surface waves, allowing the application in planar antenna array. In this work an elaborate analysis using the full wave Transverse Transmission Line - TTL method, that provides efficient and concise results is applied to the planar antennas array with PBG substrate. 相似文献
4.
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6.
We describe the topology, structure, and stability of giant fullerenes exhibiting various symmetries (I, I
h
, D
2h
, T). Our results demonstrate that it is possible to create two new families of nested chiral icosahedral (I) fullerenes namely C260@C560@C980@C1520@, ...,and C140@C380@C740@C1220@ ..., which exhibit interlayer separations of ca. 3.4 Å. These chiral fullerenes are thought to possess metalliclike conduction properties. We discuss in detail the transformation of polyhedral graphitic particles into quasispherical nested giant fullerenes by reorganization of carbon atoms, which result in the formation of additional pentagonal and heptagonal carbon rings. These spherical structures are metastable and we believe they could be formed under extreme conditions, such as those produced by high-energy electron irradiation. There is circumstantial experimental evidence for the presence of heptagonal rings within these spherical fullerenes. 相似文献
7.
Angelo C. Pinto Susan K. Do Prado Raimundo Braz Filho William E. Hull Andras Neszmelyi Gabor Lukacs 《Tetrahedron letters》1982,23(50):5267-5270
With the help of Natural Abundance 13C - 13C Coupling Constants, observed via double quantum coherence, the structural determination of VELLOZIOLONE (1), a new diterpene, has been carried out. 相似文献
8.
Garcia Ruano JL Alcudia A del Prado M Barros D Maestro MC Fernandez I 《The Journal of organic chemistry》2000,65(10):2856-2862
The addition of the lithium anions derived from (R)- and (S)-methyl and -ethyl p-tolyl sulfoxides to (S)-N-benzylidene-p-toluenesulfinamide provides an easy access route to enantiomerically pure beta-(N-sulfinyl)amino sulfoxides. Stereoselectivity can be achieved when the configurations at the sulfur atoms of the two reagents are opposite (matched pair), thus resulting in only one diastereoisomer, even for the case in which two new chiral centers are created. The N-sulfinyl group primarily controls the configuration of the carbon bonded to the nitrogen, whereas the configuration of the alpha-sulfinyl carbanion seems to be responsible for the level of asymmetric induction, as well as for the configuration of the new stereogenic C-SO carbon in the reactions with ethyl p-tolyl sulfoxides. An efficient method for transforming the obtained beta-(N-sulfinyl)amino sulfoxides into optically pure beta-amino alcohols, based on the stereoselective non-oxidative Pummerer reaction, is also reported. 相似文献
9.
Elisabeth Egholm JacobsenErik van Hellemond Anders Riise MoenLucia Camino Vazquez Prado Thorleif Anthonsen 《Tetrahedron letters》2003,44(46):8453-8455
In esterifications of secondary alcohols catalyzed by immobilized lipase B from Candida antarctica (Novozym 435) the E-values decreased during the reaction. Hydrolysis of the corresponding butanoates showed the opposite effect. When an enantiopure (R)-alcohol, related but different, was added to the transesterification reaction, the E-value was significantly enhanced. 相似文献
10.
Fernando Ribas Prado Claude Giessner-Prettre Alberte Pullman James F. Hinton Dennis Harpool Ken R. Metz 《Theoretical chemistry accounts》1981,59(1):55-69
The magnetic shielding constants of the different atoms of formamide, hydrated formamide and N-methylformamide are calculated by anab initio method. For the protons of formamide the measured differences between their chemical shifts are correctly reproduced by theory, provided that the molecular geometry used as input is carefully chosen. The differences between the values of the magnetic shielding constants calculated for formamide and hydrated formamide show that intermolecular hydrogen bonding produces variations of chemical shifts for all the atoms of the molecule except the formyl proton. The calculated chemical shift variations between formamide and N-methylformamide are compared to the experimental values and discussed in relation with different hydrogen bonding possibilities of the two molecules. The calculation of the contact term of the spin-spin coupling constants of formamide and hydrated formamide shows that in most cases the measured trends are satisfactorily reproduced and that the variations of these terms upon hydration are less than 3%. 相似文献