应用差分干涉技术研究气体与水两相传热

本文用脉冲红宝石激光器结合差分干涉技术研究气体与水的两相传热过程,实验结o果表明在水蒸汽与空气的分界面里存在大量的波纹状的细条纹;并分析了折射率与温度梯度的关系。     

痕量铬检测传感器的设计与实现

目前药品胶囊中六价铬的检测多通过实验室化学分析方法,精度虽高但难以满足现场检测的需求,针对此问题设计了一种可用于现场检测的痕量六价铬传感器。它包括化学敏感材料、光学激发模块与信号处理模块三部分,化学敏感材料将六价铬浓度转化为光信号,光学激发模块完成激光光源的稳定输出,信号处理模块实现微弱光信号的转换、放大、数据处理与检测结果的显示。实验通过制作的光电转换与信号处理电路完成痕量六价铬的快速检测,实现了检测仪器的小型化与现场检测。结果表明,在六价铬浓度10～500 μg·L-1范围内传感器检测结果呈现良好的线性,拟合后的线性方程为Y=1.542 47*X-2.353 47,线性度为0.998 62,检测下限达到10 μg·L-1,传感器响应时间为90 s,实验中选取5份药用胶囊样品做了对比检测,结果表明该传感器定量检测数据可靠,满足了痕量六价铬低成本、快速、现场检测的需求。     

集中力作用下球形颗粒六角密排堆积体的传力研究

采用铝塑板技术和复写纸技术相结合,当球形颗粒堆积体在不同的六角密排情况下受集中力作用时,对堆积体底面力的分布情况进行了定量的实验研究.结果表明：在所有排列情形下都存在明显的拱效应,且在堆积体的每一水平层面上力的分布都具有120°对称性.证实了颗粒排列形式对力的传递有很大影响.发现在纯六角密排排列时,底部颗粒的受力最为平均,单个颗粒受力的最大值在所有排列中为最小.还发现了非主力链的“聚焦”现象.对实验结果做出了理论解释. 关键词： 颗粒介质 六角密排 力链     

BESIII barrel time-of-flight （TOF） calibration using cosmic ray data

The principle of the method for the BESIII TOF calibration using cosmic ray data without magnetic field are reported in this paper. After applying calibration constants, the single-end readout time resolution could reach about 150 ps, and the time resolution for one layer is achieved to be about 110 ps. The paper also described the extraction scheme for the event start time of cosmic events.     

Tuning the Electronic Coupling and Electron Transfer in Mo2 Donor–Acceptor Systems by Variation of the Bridge Conformation

Assembling two quadruply bonded dimolybdenum units [Mo₂(DAniF)₃]⁺ (DAniF=N,N′‐di(p‐anisyl)formamidinate) with 1,4‐naphthalenedicarboxylate and its thiolated derivatives produced three complexes [{Mo₂(DAniF)₃}₂(μ‐1,4‐O₂CC₁₀H₆CO₂)], [{Mo₂(DAniF)₃}₂(μ‐1,4‐OSCC₁₀H₆COS)], and [{Mo₂(DAniF)₃}₂(μ‐1,4‐S₂CC₁₀H₆CS₂)]. In the X‐ray structures, the naphthalene bridge deviates from the plane defined by the two Mo?Mo bond vectors with the torsion angle increasing as the chelating atoms of the bridging ligand vary from O to S. The mixed‐valent species exhibit intervalence transition absorption bands with high energy and very low intensity. In comparison with the data for the phenylene analogues, the optically determined electronic coupling matrix elements (H_ab=258–345 cm^?1) are lowered by a factor of two or more, and the electron‐transfer rate constants (k_et≈10¹¹ s^?1) are reduced by about one order of magnitude. These results show that, when the electron‐transporting ability of the bridge and electron‐donating (electron‐accepting) ability of the donor (acceptor) are both variable, the former plays a dominant role in controlling the intramolecular electron transfer. DFT calculations revealed that increasing the torsion angle enlarges the HOMO–LUMO energy gap by elevating the (bridging) ligand‐based LUMO energy. Therefore, our experimental results and theoretical analyses verify the superexchange mechanism for electronic coupling and electron transfer.     

Plasmon coupling in the double-sector structure

A silver nanostructure consisting of double sectors is proposed in this paper. In addition, the plasmon resonance and electric field enhancement have been investigated theoretically. It is found that, in this structure, the multiple resonances produce, which is tunable by the parameter of the structure. The localized electromagnetic fields can be produced at the tips of the structure. In addition, the enhanced electromagnetic fields can be observed between the sectors in a wide scale at the lower energy peak. The result of the investigation has great significance for the production of practical nanostructures and the improvement of possible applications.     

Hopf bifurcation analysis in a Lorenz-type system

In this technical note, the Hopf bifurcation in a new Lorenz-type system is studied. By analyzing the characteristic equations, the existence of a Hopf bifurcation is established. Some corresponding dynamics are also discussed briefly. Numerical simulations are carried out to illustrate the main theoretical results.     

Syntheses and Bioactivity of o- or p-Trifluoromethylphenyl Phosphates

o- and p-Trifluoromethylphenyl phosphates designed as mechanism-based phosphotyrosine phosphatase inactivators have been prepared. Some of them show herbicidal activities.