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31.
Ca3Al6Si2O16: Ce3+, Tb3+ phosphors have been prepared by sol–gel method. The structure and photoluminescence properties were studied with careful.
The results indicated that the single-phased Ca3Al6Si2O16 phosphors crystallize at 1,000 °C for 2 h in conventional furnace. With appropriate concentrations of Ce3+ and Tb3+ ions into Ca3Al6Si2O16 matrix, these materials exhibit blue phosphors and white light under ultraviolet radiation. White-light emission can be achieved
because of a 400 nm emission ascribed to transitions of Ce3+ ions and three sharp peaks at 487, 543, 585 nm, respectively, resulting from transitions of Tb3+ ions. 相似文献
32.
He Wan Shasha Bai Haidong Li Junqiao Ding Zhiyuan Xie Jidong Zhang 《Journal of luminescence》2011,131(7):1393-1396
β phase polyoctylfluorene thin films were obtained by exposure to toluene vapor for various annealing times or dipping into a THF/methanol mixture. The photoluminescence and electroluminescence of PFO thin films decrease with increasing annealing time. Grazing incident X-ray diffraction of the thin films indicates that more and larger β phase crystallites will be generated in thin film exposed for longer time, which will lead to more defects that reduce photoluminescence and electroluminescence. By analyzing the mechanism of formation of β phase, we assume that the defects mainly come from the formation of out-of-plane crystalline structure. The assumption is confirmed by higher photoluminescence of β phase polyoctylfluorene thin film achieved by dipping into a THF/methanol mixture that has less out-of-plane crystalline structure. 相似文献
33.
We present a nondestructive technique to predict the refractive index profiles of isotropic planar waveguides, on which a thin gold film is deposited to as the cladding. The negative dielectric constant of the metal results in significant differences of effective indices between TE and TM modes. The two polarized modes and a surface plasmon resonance (SPR) with abundant information of the surface index can be used to construct the refractive index profiles of single-mode and two-mode waveguides at a fixed wavelength. 相似文献
34.
Based on the fluid-structure coupling theory, a localized variational principle for analyzing the sound radiation from elastic
structure submerged in water due to harmonic excitations is presented. It will be a powerful tool to formulate various numerical
methods for steady response of structural-acoustic systems. By means of this variational principle a hybrid element method,
in which an analytical solution valid in most of the surrounding water is incorporated with finite elements distributed in
the structure and its neighboring water, is devised. Computational examples are then given to demonstrate its high accuracy
and time saving.
The project supported by the National Natural Science Foundation of China (10172038) and the Doctoral Program Foundation of
Institution of Higher Education of China (20040487013). The English text was polished by Yunming Chen. 相似文献
35.
Electrogenerated Chemiluminescence of Cationic Triangulene Dyes: Crucial Influence of the Core Heteroatoms 下载免费PDF全文
Dr. Catherine Adam Antoine Wallabregue Haidong Li Jérôme Gouin Dr. Rémi Vanel Stéphane Grass Dr. Johann Bosson Dr. Laurent Bouffier Prof. Jérôme Lacour Prof. Neso Sojic 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(52):19243-19249
Trianguleniums are fascinating conjugated hexacyclic cations that exhibit interesting electronic and optical properties. Herein, the electrogenerated chemiluminescence (ECL) emission of this family of fluorescent dyes is reported for the first time. Redox behavior and fluorescence properties of eight cationic triangulene luminophores with different heteroatom patterns in the core structure and various pending substituents were examined to rationalize the ECL. Clearly, the more electron‐rich the carbocation, the more efficient the corresponding ECL; two very distinct classes of triangulenes can be drawn from these studies by using an ECL wall sufficiency formalism. 相似文献
36.
A one‐step strategy for aliphatic poly(carbonate‐ester)s with high performance derived from CO2, propylene oxide and l‐lactide 下载免费PDF全文
To improve the performance of PPC, aliphatic poly(carbonate‐ester)s were prepared in one‐step strategy from the terpolymerization of CO2, propylene oxide (PO), and l ‐lactide (L ‐LA) catalyzed by zinc glutarate. Consequently giving high‐molecular weight terpolymers (PPCLAs) in a very high yield (8450.8–9435.8 g mol?1 of Zn). The resulting terpolymers PPCLAs were characterized by 1H NMR, showing that PPCLAs had an almost alternating structure for the components of CO2, PO, and L‐LA. The influence of molecular weight and L‐LA content on the properties of PPCLAs was also investigated. Differential scanning calorimetry and thermogravimetric analysis (measurements revealed that the glass transition temperature (T g) and thermal decomposition temperature (T d) of PPCLAs are all much higher than those of PPC and increased with increasing molecular weight and L‐LA content. Tensile tests showed that the high mechanical properties of PPCLAs are due to the introduction of L‐LA into the copolymerization of CO2 and PO. Furthermore, PPCLA4 exhibits high degradability, and after 10 weeks, the weight loss increases up to 6.58%, which is significantly higher than that of PPC of 4.58%. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
37.
In this paper, we discuss an inverse problem, i.e., the reconstruction of a linear differential dynamic system from the given discrete data of the solution. We propose a model and a corresponding algorithm to recover the coefficient matrix of the differential system based on the normal vectors from the given discrete points, in order to avoid the problem of parameterization in curve fitting and approximation. We also give some theoretical analysis on our algorithm. When the data points are taken from the solution curve and the set composed of these data points is not degenerate, the coefficient matrix $A$ reconstructed by our algorithm is unique from the given discrete and noisefree data. We discuss the error bounds for the approximate coefficient matrix and the solution which are reconstructed by our algorithm. Numerical examples demonstrate the effectiveness of the algorithm. 相似文献
38.
39.
Li(3)V(2)(PO(4))(3)/graphene nanocomposites have been firstly formed on reduced graphene sheets as cathode material for lithium batteries. The nanocomposites synthesized by the sol-gel process exhibit excellent high-rate and cycling stability performance, owing to the nanoparticles connected with a current collector through the conducting graphene network. 相似文献
40.
An edge e in a 3-connected graph G is contractible if the contraction G/e is still 3-connected. The existence of contractible edges is a very useful induction tool. Let G be a simple 3-connected graph with at least five vertices. Wu [7] proved that G has at most vertices that are not incident to contractible edges. In this paper, we characterize all simple 3-connected graphs with exactly
vertices that are not incident to contractible edges. We show that all such graphs can be constructed from either a single
vertex or a 3-edge-connected graph (multiple edges are allowed, but loops are not allowed) by a simple graph operation.
Research partially supported by an ONR grant under grant number N00014-01-1-0917 相似文献