Anisotropic defect reduction in non-polar a-plane GaN grown by hydride vapor phase epitaxy on maskless patterned templates

Several non-polar a-plane GaN films had been grown by hydride vapor phase epitaxy (HVPE) on different designed metal organic chemical deposition (MOCVD) GaN templates, which exhibited various ridge-like sidewall facets surface morphologies. The templates induced a lateral growth at the early stage of the HVPE growth, and resulted in a kind of maskless epitaxy lateral overgrown (ELO) process. It is found that the dislocation reduced differently along [1 0 0 0] and [] directions in these HVPE a-plane GaN layers. In [0 0 0 1] direction, the dislocation reduction resulted from the optimal surface roughness value of the template. In [] direction, the inclined facet might be a main factor for the dislocation reduction in HVPE-GaN films. The maskless ELO process had a significant influence on decreasing the dislocation density.     

基于低分辨率色散型拉曼光谱仪的汽油苯含量快速分析

针对汽油苯含量的快速分析问题,提出了基于低分辨率色散型拉曼光谱仪的新的检测方法。由于色散型拉曼光谱中存在着严重的测量噪声和荧光背景干扰,应用多项式平滑滤波除噪声和迭代多项式拟合基线校正方法减少荧光背景的干扰。随后,分别采用岭回归、主成分回归、偏最小二乘回归方法,对炼油厂的汽油样本建立了三个苯含量的快速分析模型并对其进行验证。实验表明,基于低分辨率色散型拉曼光谱仪进行汽油苯含量分析,结合常规建模方法,重复性和再现性均满足SH/T0713—2002标准的要求,此外由于其具有低成本、小型易携带等优点,适用于日常快速分析。     

Morphological characterization of the mouthparts of the vector leafhopper Psammotettix striatus (L.) (Hemiptera: Cicadellidae)

The leafhopper Psammotettix striatus (L.) (Hemiptera: Cicadellidae), is one of the most significant economic pests of wheat in Western China. This insect vectors a phytoplasma that causes wheat blue dwarf (WBD), a severe disease limiting wheat production in the Western China. A microscopic analysis of the ultrastructure of the mouthparts of the adult was conducted using scanning electron microscopy and the putative functions of the mouthparts were determined. The piercing-sucking mouthparts of P. striatus are of the conventional type comprising a three-segmented labium with a deep groove in the anterior side, a stylet fascicle consisting of two mandibular and two maxillary stylets, and an uppermost small cone-shaped labrum. The mandibular stylets, located laterad of the maxillary stylets, have sculpture on their tips, which may function in tearing plant tissue, cutting channels into the plant tissues, and attaching the body to the host plant during molting. The maxillary stylets are interlocked to form two separate compartments, a larger food canal and a smaller salivary canal. Two dendritic canals are also found in each maxilla and one in each mandible. Four kinds of sensilla were found on the labium: s. trichodea I, s. trichodea II, s. basiconic I, s. basiconic II. These may be involved in host recognition and are likely chemo- or mechanosensory, or both.     

热泵中定容水箱保温率的研究

提出定容水箱保温率的概念及其方程。为此,本实验对定容水箱自然冷却过程中各热力参数进行了测量。根据实验所测数据及相关公式推导,得到保温率方程的经验函数关系式。同时,通过对测量曲线和经验函数曲线的拟合,验证了定容水箱保温率方程。     

Helium and point defect accumulation: (i) microstructure and mechanical behaviour

Ferritic/martensitic (F/M) steels are good candidate structural materials for the future fusion reactors and spallation sources. However, irradiation of steels is known to produce hardening, loss of ductility, shift in ductile to brittle transition temperature (DBTT) and reduction of fracture toughness and creep resistance starting at low doses. Helium (He), produced by transmutation during the irradiation, also impacts mechanical properties. Numerous experimental and theoretical studies on the evolution of the microstructure of steels under irradiation have been conducted until now. We review the effect of irradiation-induced point defects and in particular of He on the mechanical properties of F/M steels. To cite this article: R. Schäublin et al., C. R. Physique 9 (2008).     

Bright and dark optical solitons in the nonlinear Schr(o)dinger equation with fourth-order dispersion and cubic-quintic nonlinearity

By the use of an auxiliary equation, we find bright and dark optical soliton and other soliton solutions for the higher-order nonlinear Schr(o)dinger equation (NLSE) with fourth-order dispersion (FOD), cubic-quintic terms, self-steepening, and nonlinear dispersive terms. Moreover, we give the formation condition of the bright and dark solitons for this higher-order NLSE.     

Development of infrared spectral radiation measurement system of a non-luminous flame

The spectral radiation characteristic of a non-luminous flame is analyzed. The apparatus and the calibration procedure based on infrared emission spectrometry for measurements of the flame are introduced.The influence of background radiation and stray light on the measurement results could be reduced and suppressed by the design of thermolator and digital lock-in technique. A blackbody cavity was used as reference emission source to calibrate the system that completed absolute measurement. The spectral measurement range is 1-20 μm. The least measuring distance and the lowest power detected at the entrance pupil are 550 mm and 10-9 W/cm2, respectively. The experimental results show that the measure error is less than 10%.     

Variational methods for the problems of nonconservative force fields in the micropolar elastodynamics

Based on the properties of the convolution and the convolute commutation, some quasi-variational principles for the problems of nonconservative force field in the micropolar elastodynamics are given and verified in this paper. The theorem given in this paper can be applied to the theories of the nonlocal elastic mediums and the nonlocal micropolar elastic mediums.     

Second-order cnoidal waves at the free surface and interface of a two-fluid system

In this paper, using the PLK method and reductive perturbation method, we obtained the second approximation to cnoidal waves at the free surface and interface for the two-fluid system considered in [1]. The corresponding results in [3] and [4] may be obtained as special cases in this paper.Projects Supported by the Science Fund of the Chinese Academy of Sciences.     

单光束错位云纹干涉法测板的斜率和曲率

本文提出一种用高密度位相型闪耀光栅测取板的曲率和斜率的单光束错位云纹干涉法,由于这一方法具有高灵敏度。大量程和高反差的优点。可有效地用来求解板的弯曲问题。文中还给出了周边固定圆板和带缺口的方板两个应用实例。