High efficiency top-emitting white organic light-emitting devices with a (metal/organic)2 cathode

White top-emitting organic light-emitting devices (TEOLEDs) were fabricated on a glass substrate with metal/organic multilayer of (Ag/Alq₃)₂ (Alq₃ is tris-(8-hydroxyquinoline) aluminum) as cathode. White TEOLEDs with high efficiency were obtained due to the microcavity effects. And the (Ag/Alq₃)₂ cathode, which adjusted the optical characteristics of the devices, played an important role. In addition, Alq₃–Ag–Alq₃ multilayer could work as a buffer layer, which would simplify the process of encapsulation for devices. We also calculated the electroluminescence spectrum of devices encapsulated with Al₂O₃ (150 nm) and Al₂O₃(75 nm)/ZrO₂(75 nm). And the results indicated that the CIE coordinates is almost the same between with and without encapsulating.     

Disturbed solution of the El Ni?no-southern oscillation sea–air delayed oscillator

A class of delayed oscillators of El Ni?o-southern oscillation (ENSO) models is considered. Using the delayed theory, the perturbed theory and other methods, the asymptotic expansions of the solutions for ENSO models are obtained and the asymptotic behaviour of solution of corresponding problem is studied.     

Optical and atomic force microscopic study on step bunching in BaB2O4 crystal growth

The formation of macrostep during high-temperature phase of barium meta-borate (α-BaB 2 O 4) single crystal growth has been investigated by both optical in-situ observation system and atomic force microscopy (AFM).The insitu observation results demonstrate that the critical linear size of growing facet exceeding the size that the macrostep generates is significantly anisotropic.The critical linear sizes are around 280 μm and 620 μm for {1010} and {1010} planes,respectively.AFM study illustrates that macrostep train with a height of 150 nm～200 nm is one typical morphological feature of the as-grown crystal surface.The riser of each macrostep consists of several straight and parallel sub-steps,indicating the occurrence of step bunching.Additionally,triangular sub-steps with heights of several nanometers on the treads of the macrosteps are found to be another typical feature of surface morphology,which implies a microscopically competitive bunching of sub-steps between various crystallographic orientations.     

Free standing modulation doped core–shell GaAs/AlGaAs hetero‐nanowires

Modulation doped AlGaAs/GaAs core–shell nanowire structures were grown by molecular beam epitaxy. A Si delta‐doping was introduced in the AlGaAs shell around the {110} facets of the GaAs core. The wires are typically highly resistive at low temperatures. However, they show a pronounced persistent photoconductivity effect indicating activation of free carriers from the delta‐doped shell to the GaAs core. The n‐type character of the channel is demonstrated by applying a back‐gate voltage. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A DFT study on the interaction between europium,uranium and SWCNT

We investigate the electronic and band structure for the (8; 0) single-wall carbon nanotube (SWCNT) with a europium (Eu) and a uranium (U) atom outside by using the first-principles method with the density functional theory (DFT). The calculated band structure (BS), total density of state (TDOS), and projected density of state (PDOS) can elucidate the differences between the pure (8; 0) SWCNT and the nuclei outside the SWCNT. The indirect band gaps are obtained when Eu and U atom are put outside the (8; 0) CNT; they are 0.037 eV and 0.036 eV, respectively, which is much smaller than 0.851 eV for pure CNT. Compared with pure (8; 0) SWCNT, the bottom of the conduction band moves down by 0.383 eV and 0.451 eV with the Eu and U outside, and the top of valence band moves up by 0.127 eV and 0.162 eV, respectively. More significantly, the top of the valence band has exceeded the fermi-level. So, a single nucleus changes the semiconductor character of pure nanotube to semi-metal.     

Modeling of Spin Hamiltonian Parameters for Vanadyl-Doped {\bf\hbox{K}_2\hbox{SO}_4{-}\hbox{Na}_2\hbox{SO}_4{-}\hbox{ZnSO}_4} Glass

A full ligand-field energy matrix diagonalization treatment for 3d ¹ ions in tetragonal symmetry is developed on the basis of the two spin?Corbit coupling parameter model, and the contributions of the spin?Corbit coupling of the ligand ions to the optical and electron paramagnetic resonance spectra are included. Spin Hamiltonian parameters of the tetragonal ${\rm V}^{4+}$ center in $\hbox{K}_2\hbox{SO}_4 {-} \hbox{Na}_2\hbox{SO}_4{-}\hbox{ZnSO}_4$ glass are calculated from the complete energy matrix diagonalization and the perturbation theory methods. The results calculated by both methods are not only close to each other but also in good agreement with the experimental values. Furthermore, the compressed defect structure of the ${\rm (VO_6)^{8-}}$ cluster is discussed.     

Oxidation process of polysulfides in charge process for lithium�Csulfur batteries

The oxidation of polysulfides to element sulfur in charge process was studied by solution thermodynamic analysis and means of cyclic voltammetry (CV), X-ray diffraction (XRD), and charge?Cdischarge test. Basing on the solution thermodynamic analysis, the oxidation process of polysulfides to element sulfur would arise only if the charge voltage exceeds 3.36 V in a lithium?Csulfur cell employing 1.0 M LiN(CF₃SO₂)₂ in 1,2-dimethoxy ethane. Furthermore, the minimum of charge voltage which can push the oxidation would fall down with the increasing solubility of elemental sulfur in electrolyte solution. These analyses were confirmed by practical measurements. One new anodic peak corresponding to the oxidation process of polysulfides to solid sulfur was observed by CV. Both XRD patterns and charge?Cdischarge test showed that the element sulfur appeared in the cathode after the battery was charged over 3.4 V. Hence, the lithium?Csulfur cell charged over 3.4 V exhibited an improved cycle life since the capacity degradation between the first cycle and the second was depressed. In order to improve the energy efficiency, carbon disulfide was added in the electrolyte solution of lithium?Csulfur cell to increase the solubility of sulfur.     

Morphological and ultrastructural characterization of the alimentary canal in Japanese wax scale (Ceroplastes japonicus Green)

The morphology and ultrastructure of the alimentary canal in the adult female of the Japanese wax scale, Ceroplastes japonicus Green (Hemiptera: Coccoidea: Coccidae), was investigated using light microscopy, scanning electron microscopy and transmission electron microscopy. The results showed that the foregut was subdivided into a sclerotized pharynx and an oesophagus. A pair of salivary glands attached in the middle of the foregut. The loop-shaped midgut was narrow and longer than the foregut and its inner wall lined with a thick layer of epithelia. The hindgut was divided into a narrower ileum and a broader rectum, with the well-developed filter chamber enclosed in the anterior rectum. Malpighian tubules consisted of two brownish-yellow moniliform tubules with pores, approximately 1 μm in diameter, scattered on the outer surface and many spherical crystals inside the tubules.     

Design and fabrication of Gires�CTournois interferometers for?Yb-doped photonic crystal fiber laser system

A Gires?CTournois interferometer (GTI) with large dispersion compensation was designed and fabricated according to the requirement of the Yb-doped photonic crystal fiber laser system. The designed GTI can provide an average group delay dispersion (GDD) of ?1500 fs² and a high reflectance (>99.7%) from 1030 to 1050 nm. The Ion-assisted Deposition (IAD) technique was utilized to manufacture the mirror. Good agreement between the measured and designed results both for reflectance and GDD was achieved. The reflectance during 1030?C1050 nm was above 99.5% and the GDD ripple was less than ±300 fs². The GTI was used both in the intracavity dispersion compensation and extracavity pulse compression for the Yb-doped photonic crystal fiber laser system. A mode-locked soliton pulse with a 506-fs duration was recorded. An extracavity pulse compression test showed that the GTI had identical pulse compression capability as the conventional grating pairs while the energy loss was obviously reduced. Our results demonstrated that the HDM, which was able to provide quite a large amount of negative dispersion (???8×10⁴ fs²), could be an ideal alternative to replace the dispersive compensating grating pairs for the dispersion compensation of the Yb-doped photonic crystal fiber laser system.     

罗布泊遥感影像"耳纹"特征分析及其环境意义

研究典型干旱区的罗布泊,对揭示区域环境演变特征和全球变化具有重要意义.从遥感影像上的"耳纹"特征入手,通过光谱、土壤和地表参数等分析,认为:地表全盐含量和结构差异是形成罗布泊遥感影像"耳纹"特征的直接原因;光谱、全盐含量和土壤粒径的分析结果具有很好的一致性."耳纹"记录下了罗布泊地区的环境演变特征,这些特征表明:受全球环境影响,湖水在气候不断干旱的过程中逐渐干涸,干涸过程的气候调整,使罗布泊地区经历了两次相对湿润的气候环境,前一次较长,后一次很短.