4维完备Einstein流形的一些注释

本文给出了在开的定向的4维流形上存在有界曲率的完备Einstein度量的障碍．     

A Nonexistence Theorem of Proper Harmonic Morphisms Between Hyperbolic Spaces

We provide a nonexistence theorem of harmonic morphisms between hyperbolic spaces which are proper and C ²-smooth to the boundary.     

A wide band gap polymer derived from 3,6‐carbazole and tetraphenylsilane as host for green and blue phosphorescent complexes

We have synthesized a novel wide band gap polymer P36HCTPSi derived from 3,6‐carbazole and tetraphenylsilane by palladium‐catalyzed Suzuki coupling reaction. The resultant polymer shows a high glass transition temperature (217 °C) and good thermal stability. The conjugation length of P36HCTPSi is effectively confined because of the δ‐Si interrupted polymer backbone. The polymer exhibits a violet emission with a peak at 392 nm in solution, and the band gap estimated from the onset of its absorption is 3.26 eV. The high energy emission and wide band gap of P36HCTPSi make it appropriate host for green and blue emission phosphorescent materials. Efficient energy transfers from P36HCTPSi to both fac‐tris[2‐(2‐pyridyl‐kN)‐5‐methylphenyl]iridium(III) (green emission) and bis[(4,6‐difluorophenyl)pyridinato‐N,C²]‐(picolinato)iridium(III) (blue emission) were observed in photoluminescence (PL) spectra. Highly efficient phosphorescent polymer light‐emitting devices were realized by using P36HCTPSi as the host for iridium complexes, the maximum luminous efficiencies for green and blue devices were 27.6 and 3.4 cd/A, respectively. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4784–4792, 2009     

Study of the effect of ligands on the fluorescence properties of terbium ternary complexes

Four ternary complexes of Tb(III) were synthesized by introducing the first ligand (L₁) (N-phenylanthranilic acid (N-HPA), α-furoic acid (FURA)) and the second ligand (L₂) (1,10-phenanthroline (Phen), 2,2′-dipyridyl (Bipy)), respectively. These complexes were characterized by elemental analysis, infrared spectra, XRD, UV spectra and fluorescence spectra. The effect of L₁ and L₂ on the fluorescence properties of terbium complexes was discussed. It showed that all the complexes exhibited ligand-sensitized green emission. The fluorescent intensity increased in the sequence of Tb(FURA)₃Bipy < Tb(N-PA)₃Phen < Tb(FURA)₃Phen < Tb(N-PA)₃Bipy. It indicated that L₁ affected fluorescence properties of the complexes differently when the corresponding L₂ altered. Meanwhile, the influence of L₂ on the luminescence properties of the complexes also depends on L₁. The results showed that L₁ and L₂ affected each other and worked together as a whole. The matching of L₁, L₂ and Tb³⁺ ion is very important to the luminescence properties of Tb(III) ternary complexes.     

Electrochemical Deposition of Azobenzene‐Containing Network Films with High‐Contrast and Stable Photoresponse

To fabricate stable photoresponsive films and devices, a cross‐linked network that firmly fixes the position of the chromophores is an ideal structure, because aggregation and/or phase separation effects of chromophores in matrix can be effectively restrained in such robust films. Herein, the in situ electrochemical deposition (ED) of azo‐based precursors containing multielectroactive carbazole units is utilized to construct highly cross‐linked photoresponsive films. 2‐(4‐(9,9‐bis(6‐(9H‐carbazol‐9‐yl)hexyl)‐9H‐fluoren‐2‐yl)phenyl)‐1‐(4‐(9,9‐bis(6‐(9H‐carbazol‐9‐yl)hexyl)‐9H‐fluoren‐7‐yl)phenyl)diazene (BFCzAzo) with high solvability in electrolyte solution, high electroactivity, and highly efficient photoresponsive ability is synthesized by Suzuki coupling reaction as a kind of ED precursor. A highly cross‐linked photoresponsive film is fabricated by ED method using BFCzAzo as ED precursor. The film can be patterned in large area by irradiation with interfering laser beam (355 nm), and the pattern possesses excellent thermal stability and insoluble ability in both organic and inorganic solvents. Excellent reversibility of the nanostructures is demonstrated by irradiation with 550 nm laser beam.

     

High-temperature synthesis of highly hydrothermal stable mesoporous silica and Fe-SiO2 using ionic liquid as a template

Mesoporous silicas and Fe-SiO₂ with worm-like structures have been synthesized using a room temperature ionic liquid, 1-hexadecane-3-methylimidazolium bromide, as a template at a high aging temperature (150-190 °C) with the assistance of NaF. The hydrothermal stability of mesoporous silica was effectively improved by increasing the aging temperature and adding NaF to the synthesis gel. High hydrothermally stable mesoporous silica was obtained after being aged at 190 °C in the presence of NaF, which endured the hydrothermal treatment in boiling water at least for 10 d or steam treatment at 600 °C for 6 h. The ultra hydrothermal stability could be attributed to its high degree of polymerization of silicate. Furthermore, highly hydrothermal stable mesoporous Fe-SiO₂ has been synthesized, which still remained its mesostructure after being hydrothermally treated at 100 °C for 12 d or steam-treated at 600 °C for 6 h.     

拖线阵海试数据的窄带PIC自适应处理与分析

本文介绍了对拖线阵海试数据进行窄带PIC处理的方法。用梯度算法、协方差矩阵递归直接求逆算法和RMGSEF算法进行了窄带PIC自适应处理。分析了学习曲线和输出平均功率波束图,进行了稳态计算和比较。表明RMGSEF算法是一种可用于多干扰波束、收敛快、抵消性能好、便于拖线阵声呐实现实时PIC处理的最好算法。     

Evidence for macroscopic quantum tunneling of phase slips in long one-dimensional superconducting Al wires

Quantum phase slips have received much attention due to their relevance to superfluids in reduced dimensions and to models of cosmic string production in the early universe. Their establishment in one-dimensional superconductors has remained controversial. Here we study the nonlinear current-voltage characteristics and linear resistance in long superconducting Al wires with lateral dimensions approximately 5 nm. We find that, in a magnetic field and at temperatures well below the superconducting transition, the observed behaviors can be described by the nonclassical, macroscopic quantum tunneling of phase slips, and are inconsistent with the thermal activation of phase slips.     

Enhanced luminescence of rare-earth complexes Tb(1-x)Eu(x)(m-NBA)3Phen in ZnS

Rare-earth ternary complexes Tb(1-x)Eu(x)(m-NBA)(3)Phen (X=1, 0.25, 0.5, 0.75, 1.0) were synthesized and characterized by IR, DTA-TG, UV, fluorescent spectra and elemental analysis. It was found that luminescence of Eu(3+) complex was enhanced by doped with Tb(3+). It is proved by TG curve that the complexes are stable, ranging from ambient temperature to 360 degrees C in air. The organic-inorganic combined structural device was fabricated, and the electroluminescence intensity of the combined structural device was improved compared with the device of the purely organic components.