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31.
The sensitivity of Long-period fiber gratings (LPFGs), coated with high-refractive-index thin film overlays, to the refractive index and the thickness of the overlay, and to the ambient refractive index, can be enhanced with a design based on a two-overlay coating of an LPFG. The first overlay of lower refractive index than the cladding affects the guidance of a cladding mode in the second overlay of higher refractive index than the cladding. This causes a more abrupt cladding modal redistribution than with the deposition of a unique high-refractive-index overlay. The phenomenon is analyzed with a method based on a vectorial analysis of modes and the application of coupled mode theory. 相似文献
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Maria A. A. F. de C. T. Carrondo Pedro M. Matias William Heggie Philip R. Page 《Structural chemistry》1994,5(2):73-77
The structure of 4(dimethylamino)-1, 4, 4a, 5, 5a, 6, 11, 12a-octahydro-3, 5, 10, 12, 12a-pentahydroxy-6-methylene-1, 11-dioxo-2-naphthacenecarboxamide hydrobromide salt was determined by an X-ray analysis. One methacycline cation and one bromide anion were found in the asymmetric unit of an orthorhombic cell, space group P212121,a 9.580(1),b 12.147(2),c 18.735(3) å,V2180.0(5) å3, Z4,D
c 1.59 g cm–3, (MoK) 19.15 cm–1. The structure was solved and refined toR(F) 0.062 andR
w(F) 0.064 by a full matrix least-squares procedure. The conformation of the methacycline cation is found to be similar to that reported for 6-demethyl-7-chlorotetracycline hydrochloride trihydrate. 相似文献
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Ivn Maisuls Cui Wang Matias E. Gutierrez Suburu Sebastian Wilde Constantin-Gabriel Daniliuc Dana Brünink Nikos L. Doltsinis Stefan Ostendorp Gerhard Wilde Jutta Ksters Ute Resch-Genger Cristian A. Strassert 《Chemical science》2021,12(9):3270
In this work, we describe the synthesis, structural and photophysical characterization of four novel Pd(ii) and Pt(ii) complexes bearing tetradentate luminophoric ligands with high photoluminescence quantum yields (ΦL) and long excited state lifetimes (τ) at room temperature, where the results were interpreted by means of DFT calculations. Incorporation of fluorine atoms into the tetradentate ligand favors aggregation and thereby, a shortened average distance between the metal centers, which provides accessibility to metal–metal-to-ligand charge-transfer (3MMLCT) excimers acting as red-shifted energy traps if compared with the monomeric entities. This supramolecular approach provides an elegant way to enable room-temperature phosphorescence from Pd(ii) complexes, which are otherwise quenched by a thermal population of dissociative states due to a lower ligand field splitting. Encapsulation of these complexes in 100 nm-sized aminated polystyrene nanoparticles enables concentration-controlled aggregation-enhanced dual emission. This phenomenon facilitates the tunability of the absorption and emission colors while providing a rigidified environment supporting an enhanced ΦL up to about 80% and extended τ exceeding 100 μs. Additionally, these nanoarrays constitute rare examples for self-referenced oxygen reporters, since the phosphorescence of the aggregates is insensitive to external influences, whereas the monomeric species drop in luminescence lifetime and intensity with increasing triplet molecular dioxygen concentrations (diffusion-controlled quenching).Pt(ii) and Pd(ii) complexes with unprecedented photophysical properties were developed. Encapsulation in nanoparticles boosted their performance while rendering them as self-referenced oxygen sensors. 相似文献
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We report ab initio computations with the Vienna Ab initio Simulation Package (VASP) aimed at elucidating the adsorption mechanism of graphene-like structures on (111) Pd, Pt, and Ni surfaces. To study the adsorption properties, we simulate an already-formed graphene layer. We present a comparative discussion of the graphene interactions with the three metals, focusing on the very particular adsorption of graphene over Pd. 相似文献
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Vega-Hissi Esteban G. Andrada Matias F. Díaz Mario G. Garro Martinez Juan C. 《Molecular diversity》2019,23(4):985-995
Molecular Diversity - Although many sulfur containing garlic compounds present antioxidant activity, little is known about molecular mechanisms through which these compounds react with reactive... 相似文献
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Mauricio Gomes Constantino Luiz Gonzaga de Oliveira Matias Gil Valdo José da Silva Vladimir Constantino Gomes Heleno Maria Teresa do Prado Gambardella 《合成通讯》2013,43(24):4285-4295
Abstract: In this paper we describe a very short stereoselective synthesis of the β-ethoxylactone 13, a model structure for compounds isolated from Otoba parvifolia. The method, which also produces β-hydroxy-esters and β-hydroxy-lactones, is based on a chemo- and stereoselective Reformatsky reaction. 相似文献
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Matias?NavarroEmail authorView authors OrcID profile Oscar?Palmas Didier?A.?Solis 《Mediterranean Journal of Mathematics》2018,15(6):215
In this paper, we develop the notion of screen isoparametric hypersurface for null hypersurfaces of Robertson–Walker spacetimes. Using this formalism we derive Cartan identities for the screen principal curvatures of null screen isoparametric hypersurfaces in Lorentzian space forms and provide a local characterization of such hypersurfaces. 相似文献