农杆菌介导转化新疆棉花体系的优化

以新疆主栽棉花品种新陆早19号和新陆早23号下胚轴为外植体,以GUS基因为报告基因,通过检测GUS基因在转化后的棉花下胚轴中瞬时表达情况,分析了菌液浓度、浸染时间、乙酰丁香酮浓度、超声波辅助处理、共培养温度和共培养时间等因素对GUS瞬时表达的影响.实验结果表明:菌液浓度OD600=0.5,浸染时间15 min,乙酰丁香酮浓度100μmol/L,24 C共培养72 h的转化条件下GUS基因瞬时表达率最高.     

超宽带可调谐SOA四波混频波长变换器的实验研究

基于半导体光放大器(SOA)光纤环形激光器中的双泵浦四波混频效应,构成超宽带并且完全透明的波长变换器,成功实现1550nm窗口2.5Gb/s信号的可调谐波长变换,变换效率在50nm范围内保持基本平坦,同时测出了SOA增益和自发辐射(ASE)噪音功率的关系.实验结果表明,在一定限制条件下,提高泵浦功率可以提高变换信号的信噪比.     

Novel Image Optimization Method for Joint Photoacoustic Tomography

The distribution of speed of sound （SOS） in biomedical tissue and delay compensation （DC） have significant impact on the image quality of photoacoustic tomography （PAT）. When imaging human peripheral joints, using fixed SOS and DC can only ensure that the reconstructed images are focused in a limited depth range, whereas they are defoeused at other depths, which cause severe artifacts and blurring. In this work, a linear-DC based reconstruction approach is proposed to focus the whole PAT image region. It is proved by two in vivo experiments that, compared with traditional delay-and-sum back projection algorithms, the proposed method can effectively optimize the image quality of articular tissues in PAT.     

Effect of annealing temperature on structure, magnetic properties and optical characteristics in Zn0.97Cr0.03O nanoparticles

The Cr-doped zinc oxide (Zn_0.97Cr_0.03O) nanoparticles were successfully synthesized by sol-gel method. The relationship between the annealing temperature (400 °C, 450 °C, 500 °C and 600 °C) and the structure, magnetic properties and the optical characteristics of the produced samples was studied. The results indicate that Cr (Cr³⁺) ions at least partially substitute Zn (Zn²⁺) ions successfully. Energy dispersive spectroscopy (EDS) measurement showed the existence of Cr ion in the Cr-doped ZnO. The samples sintered in air under the temperature of 450 °C had single wurtzite ZnO structure with prominent ferromagnetism at room temperature, while in samples sintered in air at 500 °C, a second phase-ZnCr₂O₄ was observed and the samples were not saturated in the field of 10000 Oe. This indicated that they were mixtures of ferromagnetic materials and paramagnetic materials. Compared with the results of the photoluminescence (PL) spectra, it was reasonably concluded that the ferromagnetism observed in the studied samples was originated from the doping of Cr in the lattice of ZnO crystallites.     

Optimal orientation field to manufacture magnetostrictive composites with high magnetostrictive performance

Magnetostrictive properties have relationship with the applied orientation field during the preparation of giant magnetostrictive composites. To understand the dependence of the optimal orientation field on particle volume fraction, composites with 20%, 30% and 50% particles by volume were fabricated by distributing Terfenol-D particles in an unsaturated polyester resin under various orientation fields. Their magnetostrictive properties were tested without pre-stress at room temperature. The results indicate that as the particle volume fraction increases, the optimal orientation field increases. The main reason for this phenomenon is the packing density for the composites with higher particle volume fraction is larger than that for those with lower particle content.     

Cesium 6S(1/2) --> 8S(1/2) two-photon-transition-stabilized 822.5 nm diode laser

A cesium 6S(1/2) --> 8S(1/2) two-photon-transition (TPT)-stabilized 822.5 nm diode laser is reported for the first time to our knowledge. Allan deviation of 4.4 x 10(-13) (60 s) was achieved, and the possible systematic errors were evaluated as smaller than 2 kHz. We demonstrate that the cesium TPT-stabilized diode laser could be a reliable frequency reference at 822.5 nm wavelength.     

1.8m望远镜变形次镜波前拟合能力分析

波前拟合能力分析是变形次镜研制工作的重要组成部分,是基于变形次镜的新型自适应光学系统研制的重要基础.以拟合误差为评价标准,采用有限元计算所得驱动器影响函数对1.8 m望远镜变形次镜四个备选方案进行了泽尼克(Zernike)多项式、Kolmogorov湍流大气畸变相位屏拟合能力分析.结果表明73单元变形次镜波前拟合能力较...     

Luminescent properties of Dy doped SrMoO4 phosphor

Trivalent dysprosium ions (Dy³⁺) doped strontium molybdate (SrMoO₄) phosphors were synthesized by solid-state reaction and their photoluminescence (PL) properties were investigated. X-ray powder diffraction (XRD) analysis confirmed the formation of SrMoO₄:Dy³⁺. PL measurements indicated that the phosphor exhibited intense emission at 482, 490 (⁴F_9/2→⁶H_15/2) and 575 nm (⁴F_9/2→⁶H_13/2) under UV excitation. The effect of the doping concentration of Dy³⁺in SrMoO₄:Dy³⁺ on the PL was investigated in detail. Na⁺ ion was a good charge compensator for SrMoO₄:Dy³⁺.     

Tunable microwave generation based on a Brillouin fiber ring laser and reflected pump

A simple approach for photonic generation of a tunable microwave signal is proposed and successfully demonstrated. By mixing the output from a single-longitudinal-mode Brillouin fiber ring laser with the reflected laser pump at photodetector, a microwave signal at the Brillouin shift can be obtained. Since the Brillouin shift can be changed by tuning the pump wavelength, tunable microwave can be generated. As a result a microwave signal tunable from 10.39 to 10.67 GHz has been achieved, with linewidth less than 600 KHz.