Luminescent Properties of a Polymer Photoluminescent Composite Containing the Binuclear (EU,TB) Complex as an Emitter

Uninuclear europium (Eu), as well as binuclear Eu and terbium (Tb), complexes were synthesized using acrylic acid (AA) as the first ligand and 1,10-phenanthroline (Phen) as the second ligand. The relative weight ratio of the europium (III) (Eu³⁺) to terbium (III) (Tb³⁺) ions of the binuclear complex was 1:1 as determined via energy dispersive X-ray analysis. The structures of the Eu(AA)₃Phen and Eu_0.5Tb_0.5(AA)₃Phen complexes were characterized by Fourier transform infrared spectroscopy. A series of tri-cellulose acetate (TCA)/ the Eu(AA)₃Phen and TCA/Eu_0.5Tb_0.5(AA)₃Phen composites were prepared by solution blending, and their luminescent properties were investigated by fluorescence spectrophotometry. The excitation spectra of all composites indicated that the TCA matrix probably affected the energy absorption and transfer of organic ligands. In TCA/Eu_0.5Tb_0.5(AA)₃Phen composites the introduced Tb³⁺ ions had some influence on energy absorption and transfer of organic ligands; the energy transfer process of the complex is suggested to be as follows: Phen→AA→Tb³⁺ion→Eu³⁺ion. The emission spectra indicated that the luminescent intensity of the TCA/Eu_0.5Tb_0.5(AA)₃Phen composites was noticeably stronger than that of the TCA/Eu(AA)₃Phen composites, suggesting that the comparatively stable and high-efficiency energy transfer process was only slightly influenced by the TCA matrix. In summary, the TCA/Eu_0.5Tb_0.5(AA)₃Phen (90/10) composite possesses fine luminescent properties for potential usage as red fluorescent materials.     

Symmetries and generalizedW∞ algebra of the modified KP equation

The infinitely many symmetries with arbitrary functions of timet for the potential modified Kadomtsev-Petviashvilli equation are obtained by using a simple direct method. These symmetries constitute a generalization of the well-knownW algebra.     

烷基苯的热力学性质与分子拓扑指数的关系研究

此文分析了烷基苯的结构特点，以分子的拓扑指数为结构参数，研究了苯、烷基系列的燃烧热，生成自由能等八种热力学性质与结构参数的关系，提出计算热力学性质的一个通用关系式Ｙ＝ａ·Ｎ＋ｂ·Ｒ＋ｃ·ＮＲ＋ｄ，用计算机处理，得到一系列经验公式，计算结果表明：烷基苯系列的热力学性质与拓扑指数相关性能很好。     

Propagation of cosh-Gaussian beams diffracted by a circular aperture in turbulent atmosphere

An analytical formula for the average intensity of cosh-Gaussian (ChG) beams diffracted by an aperture in turbulent atmosphere is derived and some limiting cases are discussed. By using the average intensity formula, some numerical simulation comparisons are made and some special cases are studied, especially the influences of the ChG beam parameter (Ω₀), the propagation distance, the aperture and its size on the average normalized intensity distribution. It is determined that the evolution properties of the average normalized intensity profile in turbulent atmosphere with aperture are different not only from those of free space with aperture but also from those in turbulent atmosphere without aperture. PACS 42.68.Bz; 42.79.Ag; 42.25.Fx     

102Ru核振动到转动演化的微观研究

基于微观sdIBM-2方案和实验单粒子能量值, 在最普遍的哈密顿量下, 用两组不同的核子-核子等效相互作用参数, 分别很好地再现了¹⁰²Ru核的振动带能谱和转动带能谱及其演化过程. 微观和唯象的研究指认: 1) 这两种激发模式的共存区是能态8⁺₁—12⁺₁(即E_x=2.500—4.000 MeV); 态 8⁺_{1关键词： 微观sdIBM-2方案 形状演化 玻色子 102Ru核')" href="#">¹⁰²Ru核}     

燃气透平叶片表面颗粒沉积特性数值研究进展

污染物颗粒在燃气透平叶片表面及冷却通道内的沉积将影响透平叶片的冷却特性和安全服役寿命。国外许多研究机构对燃气透平叶片表面污染物颗粒沉积特性及其与叶片气膜冷却的相互作用机制进行了持续研究。本文首次系统总结了近年来燃气透平叶片表面污染物颗粒沉积特性数值研究进展,重点介绍了燃气透平叶栅流道内污染物颗粒的沉积机制、颗粒沉积和脱离物理模型以及颗粒沉积与透平叶片冷却特性相互作用的数值模拟方法和研究成果。基于当前研究热点和发展趋势,结合作者的研究经历,指出了国内在研发先进燃气轮机透平冷却结构时应注意的问题和方向,为高效、燃料适应性更广的燃气轮机技术自主开发奠定基础。     

First-principles investigation on ideal strength of B2 NiAl and NiTi alloys

For B2 NiAl and NiTi intermetallic compounds, the ideal stress–strain image is lack from the perspective of elastic constants. We use first-principles calculation to investigate the ideal strength and elastic behavior under the tensile and shear loads. The relation between the ideal strength and elastic constants is found. The uniaxial tension of NiAl and NiTi along <001> crystal direction leads to the change from tetragonal path to orthogonal path, which is driven by the vanishing of the shear constant C(66). The shear failure under {110}{111} shear deformation occurring in process of tension may result in a small ideal tensile strength(~ 2 GPa) for NiTi. The unlikeness in the ideal strength of Ni Al and Ni Ti alloys is discussed based on the charge density difference.     

1.54 μm Light emission from Er/O and Er/F doped Si p–i–n diodes grown by molecular beam epitaxy

Various light emitting devices (LED) have been processed using Er/O- and Er/F-doped Si layered structures grown by molecular beam epitaxy (MBE) at low temperature. A comparative study has been carried out in order to provide more understanding of the electroluminescence (EL) excitation and de-excitation mechanisms in particular at a high injection current regime. Comparing the experimental results with model calculations the values of excitation cross section, σ_ex, and effective Auger coefficient, C_A, have been determined for various devices operated at different biases. Time-resolved EL measurements of these Er/O- and Er/F-doped MBE Si structures, using an experimental set-up with a time response of 200 ns, have been performed with different excitation conditions. Besides the spontaneous Er emission (700 μs), some fast EL decay processes associated with the Auger energy transfer via free carriers (4 μs), and the hot carrier effects (200 ns) have been identified.     

界面动力学对过冷熔体中球晶生长界面形态的影响

考虑了在非平衡凝固条件下球晶生长过程中界面动力学系数随界面温度的变化,利用渐近分析方法求出了在过冷熔体中球晶生长温度场和界面的近似解析解,研究了非线性界面动力学过冷对于过冷熔体中球晶界面形态和生长速度的影响.研究表明,界面动力学系数越大,球晶的生长速度越快; 反之,表明界面动力学系数越小,球晶的生长速度越慢.与忽略界面动力学的情形比较,在球晶生长过程中依赖于界面温度变化的界面动力学显著地减缓了晶体生长的速度. 关键词： 球晶 界面形态 渐近分析     

基于叶绿素荧光光谱分析的黄瓜霜霉病害预测模型

为了实现对黄瓜病害的快速无损准确预测,基于激光诱导叶绿素荧光光谱分析技术,建立了温室黄瓜霜霉病害的预测模型.通过测定健康叶片、病菌接种3d叶片和接种6d叶片的光谱曲线,采用一阶导数光谱预处理方法,结合主成分分析数据降维方法对三组光谱数据进行特征信息提取后,建立主成分得分散点图,依据累积贡献率选取10个主成分代替导数光谱...