Structure and coordination behavior of 2,3-bis(2-furanyl)quinoxaline

The title compound crystallizes in the orthorhombic system, space group Pna2₁, with a = 15.721 (5) Å, b = 16.945 (5) Å, c = 4.6961 (15) Å, V = 1251.0 (7) ų, and Z = 4. One furanyl ring is rotated with respect to the quinoxaline group by 66.4(2)°, and another furanyl ring almost lies coplanar with the quinoxaline moiety. Although it has potential for chelation involving the furanyl oxygen atom and the nearest nitrogen atom of the quinoxaline group, poor coordination behavior was observed while attempting to synthesize its complexes with a metal center like Ru(II), Cu(II), or Co(III), entirely different from its analogue 2,3-bis(2-pyridyl)quinoxaline. This is most likely due to the weak donating ability of the furanyl oxygen atom and the steric hindrance.     

Crystal and molecular structure of main adduct of benzaldoxime dehydrodimer and styrene

Three 1:1 adducts have been obtained by heating benzaldoxime dehydrodimer with styrene. The main product possesses the structure of bis-nitrone type. A radical addition mechanism is proposed.     

Synthesis,crystal structure and spectroscopic properties of a copper(II) complex of the Schiff-base derived from picolinaldehyde N-oxide and 4-aminoantipyridine

The Schiff-base (PNOAAP) derived from picolinaldehyde N-oxide and 4-aminoantipyrine, and its copper(II) complex: [Cu(PNOAAP)₂(EtOH)₂]₂(ClO₄)₄ (1) has been prepared and characterized by elemental analysis, i.r., ¹H-n.m.r. spectrum, and single crystal X-ray crystallographic determination. The PNOAAP ligand isomerizes from trans to cis after chelating to copper(II).     

Influence of nanomechanical force on the electronic structure of InAs/GaAs quantum dots

We show nanomechanical force is useful to dynamically control the optical response of self-assembled quantum dots, giving a method to shift electron and heavy hole levels, interval of electron and heavy hole energy levels, and the emission wavelength of quantum dots (QDs). The strain, the electron energy levels, and heavy hole energy levels of InAs/GaAs(001) quantum dots with vertical nanomechanical force are investigated. Both the lattice mismatch and nanomechanical force are considered at the same time. The results show that the hydrostatic and the biaxial strains inside the QDs subjected to nanomechanical force vary with nanomechanical force. That gives the control for tailoring band gaps and optical response. Moreover, due to strain-modified energy, the band edge is also influenced by nanomechanical force. The nanomechanical force is shown to influence the band edge. As is well known, the band offset affects the electronic structure, which shows that the nanomechanical force is proven to be useful to tailor the emission wavelength of QDs. Our research helps to better understand how the nanomechanical force can be used to dynamically control the optics of quantum dots.     

Electron beam evaporation deposition of cadmium sulphide and cadmium telluride thin films： Solar cell applications7

Cadmium sulphide （CdS） and cadmium telluride （CdTe） thin films are deposited by electron beam evaporation. Atomic force microscopy （AFM） reveals that the root mean square （RMS） roughness values of the CdS films increase as substrate temperature increases. The optical band gap values of CdS films increase slightly with the increase in the substrate temperature, in a range of 2.42-2.48 eV. The result of Hall effect measurement suggests that the carrier concentration decreases as the substrate temperature increases, making the resistivity of the CdS films increase. CdTe films annealed at 300 ℃ show that their lowest transmittances are due to their largest packing densities. The electrical characteristics of CdS/CdTe thin film solar cells are investigated in dark conditions and under illumination. Typical rectifying and photovoltaic properties are obtained.     

二维光子晶体禁带特性研究

采用平面波展开法对二维光子晶体分别在E和H极化下的带隙进行了计算. 考虑了填充比、晶格结构、介电常数对最大绝对帯隙的影响. 结果表明,不论是正方晶格还是三角晶格,TM模在介质柱型光子晶体中更容易形成带隙;TE模在空气孔型光子晶体中更容易形成带隙. 填充比一定,最大绝对帯隙宽度并非随着介电常数增大总是增大,而是存在一个峰值. 相对介电常数一定,最大绝对帯隙宽度随填充比的变化也存在一个峰值. 不论空气孔型还是介质柱型结构,三角晶格比正方晶格更容易形成帯隙. 关键词： 平面波展开法 TE模 TM模 最大绝对帯隙     

乙烯和丙烯自由基共聚反应的多尺度模拟模型

结合量子化学和传统过渡态理论计算了乙烯和丙烯自由基聚合反应的速率常数.利用速率常数定义了聚合反应几率(Pijl),构造了乙烯和丙烯共聚合反应的粗粒化动力学模拟模型,并利用该模型研究了不同组成比的乙烯和丙烯的共聚合反应.发现反应速率常数和链端自由基周围的单体浓度都影响链上组分的序列分布.     

Syntheses and Characterization of Homochiral Three-dimensional Lanthanide-organic Frameworks Based on Ln4O4 Clusters and L-Aspartic Acid

Four isostructural lanthanide compounds formulated as {[Ln4(μ3-OH)4(L-asp)3- (H2O)10](ClO4)5·10H2O}n (Ln=Nd (1), Sm (2), Eu (3), Gd (4); asp=aspartic acid) were synthe- sized by a conventional solution reaction. Their structures were characterized by single-crystal X-ray diffraction, IR spectroscopy and elemental analyses (EA). It reveals that they crystallize in the chiral P212121 space group. Their structures feature a homochiral three-dimensional (3D) lan- thanide-organic framework, which contains a cubic [Ln4(μ3-OH)4]8+ cluster sub-building unit (SBU). Additionally, the photoluminescence property of Eu compound was investigated in the solid-state at room temperature.     

Optimal dynamic bandwidth allocation for complex networks

Traffic capacity of one network strongly depends on the link’s bandwidth allocation strategy. In previous bandwidth allocation mechanisms, once one link’s bandwidth is allocated, it will be fixed throughout the overall traffic transmission process. However, the traffic load of every link changes from time to time. In this paper, with finite total bandwidth resource of the network, we propose to dynamically allocate the total bandwidth resource in which each link’s bandwidth is proportional to the queue length of the output buffer of the link per time step. With plenty of data packets in the network, the traffic handling ability of all links of the network achieves full utilization. The theoretical analysis and the extensive simulation results on complex networks are consistent. This work is valuable for network service providers to improve network performance or to do reasonable network design efficiently.     

Influence of disorder and deformation on the optical properties of two-dimensional photonic crystal waveguide

We investigate the effect of disorder and mechanical deformation on two- dimensional photonic crystal waveguide. The dispersion characteristics and transmittance of the waveguide are studied by using the finite element method. Results show that the geometric change of the dielectric material perpendicular to the light propagation direction has a larger influence on the waveguide characteristics than that parallel to the light propagation direction. Mechanical deformation has an obvious influence on the performance of the waveguide. In particular, longitudinal deformed structure exhibits distinct optical characteristics from the ideal one. Studies on this work will provide useful guideline to the fabrications and practical applications based on photonic crystal waveguides.