静态顶空/气相色谱-质谱联用快速测定茶粉中残留溶剂

在基质改性剂H2O,平衡温度55℃,进样针温度60℃,传输线温度65℃,平衡加热时间30min,顶空气体进样量0.2mL等顶空取样条件下,建立了静态顶空取样,气-质联用技术快速测定茶粉中残留溶剂乙酸乙酯、氯仿的方法。结果表明该方法简单快速、准确度高、重复性好。     

Co/HZSM-5分子筛催化醛氨缩合反应活性的研究

研究了担载不同钴含量的Co/HZSM-5分子筛的表面酸性以及醛氨缩合反应的催化活性和选择性.结果表明,钴组元的引入,使HZSM-5表面L酸增加,B酸略减少;弱酸增加,强酸减少,总酸量增加;催化剂的孔体积和比表面都随钴含量的增加而减小.反应中吡啶、2-甲基吡啶和3-甲基吡啶的总收率随担载的钴含量的增加先增加后降低,当钴担载量为0.51%时,催化活性达到最高,三种吡啶同系物的收率达到最大(61.3%).此外,还讨论了Co/HZSM-5催化剂的表面酸性与醛氨缩合催化活性的关系.     

Optimization design of flat-band long-period grating

We present a method to optimize the flat-band long-period fiber Bragg grating (FBG) in this letter. The method is based on the particle swarm optimization method and the matrix transmission method. The optimized refractive modulation profile does not introduce so many phase shifts and is easier to fabricate compared with that of layer-peeling method which introduces lots of π phase shift at each zero point of apodization profile in designing for the same problem.     

正交各向异性平面弹性问题物性值V_(12)和G_(12)的反分析

采用边界元法和卡尔曼滤波对正交各向异性平面弹性问题物性值进行反分析,由有限个观测点的位移值反算出材料常数ν１２和 Ｇ１２．算例表明了该方法的有效性．     

钴铜铝水滑石类化合物的合成及其催化氧化对甲酚：Ⅰ.水滑石的合成及 …

用共沉淀法合成了以钴为主的水滑石型化合物，用ＸＲＤ，ＩＲ等对其及热分解产物进行了表征。结果表明，水滑石经过焙烧，逐渐失去层间的Ｈ２Ｏ，ＯＨ＾＝和ＣＯ＾２－３，转化成尖晶石结构。比表面积测定和ＣＯ２－ＴＰＤ结果表明，焙烧温度和产物的Ｃｏ：Ｃｕ比对表面积和碱性均有明显的影响。     

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.     

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     

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.     

Donor-bound electron states in a two-dimensional quantum ring under uniform magnetic field

The electron states in a two-dimensional GaAs/AlGaAs quantum ring are theoretically studied in effective mass approximation. On-centre donor impurity and uniform magnetic field perpendicular to the ring plane are taken into account. The energy spectrum with different angular momentum changes dramatically with the geometry of the ring. The donor impurity reduces the energies with an almost fixed value; however, the magnetic field alters energies in a more complex way. For example, energy levels under magnetic field will cross each other when increasing the inner radius and outer radius of the ring, leading to the fact that the arrangement of energy levels is distinct in certain geometry of the ring. Moreover, energy levels with negative angular momentum exhibit the non-monotonous dependence on the increasing magnetic field.