纳米二氧化钛-高锰酸钾协同光催化氧化体系快速测定化学需氧量

以纳米TiO2-KMnO4协同光催化氧化体系为基础,结合分光光度法建立了一种快速测定水样中化学需氧量(COD)的简便方法。本方法具有线性范围宽、抗氯离子干扰能力强等优点。在选定的最优条件下,线性范围为0.1~320mg/L;当氯离子含量在1500mg/L以内时,相对误差小于5%。此方法适用于污染程度低的自来水、地表水或中等污染程度的工业废水中COD值的快速测定。     

Effect of Stress-Dependent Thermal Conductivity on Thermo-Mechanical Coupling Behavior in GaN-Based Nanofilm Under Pulse Heat Source

The thermal properties of a nanostructured semiconductor are affected by multi-physical fields,such as stress and electromagnetic fields,causing changes in temperature and strain distributions.In this work,the influence of stress-dependent thermal conductivity on the heat transfer behavior of a GaN-based nanofilm is investigated.The finite element method is adopted to simulate the temperature distribution in a prestressed nanofilm under heat pulses.Numerical results demonstrate the effect of stress field on the thermal conductivity of GaN-based nanofilm,namely,the prestress and the thermal stress lead to a change in the heat transfer behavior in the nanofilm.Under the same heat source,the peak temperature of the film with stress-dependent thermal conductivity is significantly lower than that of the film with a constant thermal conductivity and the maximum temperature difference can reach 8.2 K.These results could be useful for designing GaN-based semiconductor devices with higher reliability under multi-physical fields.     

A Novel 3D Na(I) Coordination Polymer Constructed by 3,5-Bis(4'-Carboxy-Phenyl)-1,2,4-Triazole: Synthesis,Crystal Structure,and Photocatalytic Property

Crystallography Reports - A novel 3D metal coordination polymer, {[Na4(µ2-H2O)(DMF)2(BCT)2]?DMF}n (I) (DMF = N,N-dimethylformamide, H2BCT =...     

低压供热涂层材料制备及热性能研究

低压供热技术具有安全系数高和节能降耗等优势,因而成为石化稠油长输管线、风力发电叶片冬季防覆冰和室内供暖等领域的研究热点之一。本文制备了一系列低压供热涂层材料,研究不同碳功能填料对涂层发热速率、发热功率及最高发热温度的影响规律,并揭示石墨烯和碳纤维对提升涂层材料热性能的协同作用。其中石墨烯纳米片的还原程度对材料热性能具有重要影响,降低其表面官能团密度对提升涂层供热特性具有促进作用,但是官能团密度过低会导致石墨烯纳米片的团聚现象,引起涂层发热不均匀。加入适量碳纤维可以提高石墨烯的均匀分散性,提升发热速率。优化石墨烯纳米片和碳纤维的比例后,采用24V电压驱动时,涂层材料的发热速率达到7.1℃·s^-1,功率密度为800W·m^-2,最高发热温度为124℃。     

变温场中具损伤粘弹性矩形板的非线性动力响应分析

基于热粘弹性理论、Von Karman板理论和连续损伤力学,导出了二维状态下各向同性材料的变温粘弹性本构方程,建立了含损伤效应的各向同性粘弹性矩形板在变温场中的非线性运动控制方程,且应用有限差分法对问题进行求解.算例中,讨论了损伤演化及温度场等因素对粘弹性矩形板非线性动力学行为的影响,得出一些有意义的结论.     

Applications of Markov spectra for the weighted partition network by the substitution rule

The weighted self-similar network is introduced in an iterative way. In order to understand the topological properties of the self-similar network, we have done a lot of research in this field.Firstly, according to the symmetry feature of the self-similar network, we deduce the recursive relationship of its eigenvalues at two successive generations of the transition-weighted matrix.Then, we obtain eigenvalues of the Laplacian matrix from these two successive generations.Finally, we calculate an accurate expression for the eigentime identity and Kirchhoff index from the spectrum of the Laplacian matrix.     

Optical Trapping with Focused Surface Waves

Near-field optical trapping can be realized with focused evanescent waves that are excited at the water–glass interface due to the total internal reflection, or with focused plasmonic waves excited on the water–gold interface. Herein, the performance of these two kinds of near-field optical trapping techniques is compared using the same optical microscope configuration. Experimental results show that only a single-micron polystyrene bead can be trapped by the focused evanescent waves, whereas many beads are simultaneously attracted to the center of the excited region by focused plasmonic waves. This difference in trapping behavior is analyzed from the electric field intensity distributions of these two kinds of focused surface waves and the difference in trapping behavior is attributed to photothermal effects due to the light absorption by the gold film.     

基于简单MOPA结构实现3.08 kW全光纤窄线宽线偏振激光输出

基于简单的主振荡功率放大结构,演示了一种高功率窄线宽线性偏振全光纤激光器,其最大输出功率为3.08 kW,3 dB线宽为0.2 nm。在整个功率缩放过程中,偏振消光比约为94%,光束质量M 2约为1.4。这是国内外首次实现3 kW全保偏光纤激光输出,与基于相位调制的窄线宽激光器相比,该激光器可实现近似的线宽,同时具有受激布里渊散射阈值高、系统结构简单、成本低等特点。     

表面喷砂对有机玻璃沿面闪络性能影响

绝缘子表面粗糙处理是提升其沿面闪络性能的重要途径,表面粗糙化处理方式不当,极易带来表面结构不均匀,难以获得稳定耐压性能的绝缘材料。为提升绝缘子表面粗糙处理的均匀性,本文利用表面喷砂技术对圆柱形有机玻璃(PMMA)绝缘子进行了粗糙化处理研究,以球形二氧化硅(SiO2)颗粒为工作介质,研究了不同喷砂粒径、氢氟酸后处理等因素对绝缘材料表面形貌和组分的影响,并利用短脉冲高压测试平台对喷砂处理前后有机玻璃绝缘子样品进行了真空沿面闪络性能测试。研究结果表明,喷砂处理在有机玻璃表面形成了较为均匀的凹坑,HF酸能够有效去除表面残留的SiO2颗粒,具有表面喷砂粗糙结构的绝缘子沿面闪络电压得到了稳定提升,相较于未处理的绝缘子闪络电压提升了约80%。     

OCS分子在128 nm附近的光解动力学研究：S(3PJ=2,1,0)、S(1D2)以及S(1S0)产物通道

本文利用时间切片离子成像技术对OCS分子进行了真空紫外波段的光解动力学研究. 在四个光解光波长(从129.32到126.08 nm)下测量了硫原子解离产物S(³P_J=2,1,0)、S(¹D₂)、S(¹S₀)的速度影像,并从中清晰地发现了四个主要的解离产物通道：S(³P_J=2,1,0)+CO(X¹Σ⁺),S(³P_J=2,1,0)+CO(A³π),S(¹D₂)+CO(X¹Σ⁺)和S(¹S₀)+CO(X¹Σ⁺). 在实验影像中,产物CO分子的部分振动态结构能够得到分辨. 实验还获取解离产物总平动能谱,产物分支比和角分布. 对实验结果进行分析显示除绝热解离通道S(³P_J=2,1,0)+CO(A³π)之外,在其他三个产物通道中非绝热效应都起到非常重要的作用.