Cavity Ring Down Laser Absorption Spectroscopy of NiI

用激光蒸发/反应、超声射流和光腔衰荡吸收光谱方法研究NiI在445～510 nm的吸收光谱. 发现两个新的跃迁体系[21.3]²?_5/2～X²?_5/2和[21.9]²Π_3/2～X²?_5/2,并且观察到了同位素分子⁵⁸NiI和⁶⁰NiI光谱. 同时计算得到了电子态[21.3]^{2相似文献}   

基于洗涤品生产的化工实训课程设计*

为适应地方院校应用型转型发展的要求,结合化工专业特色,设计了基于洗涤品生产的校内化工实训课程。该课程内容丰富、可操作性强。内容涵盖了配方设计、小试实验、生产操作、产品罐装、性能测试、安全教育等环节。课程采用教、学、做、产一体化的教学模式,运行效果显著,可激发学生的学习兴趣,培养学生的科研思维与实践创新能力。     

Generating monoenergetic proton beam by using circularly polarlzed laser

The interaction of ultrashort intense circularly polarized laser with ultra thin overdense foil is studied by particle-in-cell simulation and analytic model.It is found that with the balance between pondermotive force and electrostatic force,highly quasi-monoenergetic proton beam can be generated by Phase Stable Acceleration(PSA)process.As in conventional accelerators,ion will be accelerated and bunched up in the longitudinal direction at the same time.     

Mechanism studies of thermolysis process in copolyamide 66 containing triaryl phosphine oxide

Thermolysis behavior of flame-retardant copolyamide 66 (FR-PA66) in the presence of triaryl phosphine oxide (TPO) has been studied using different techniques such as differential scanning calorimetry, thermal gravimetric analysis, Fourier transform-infrared spectroscopy, and gas chromatography–mass spectrometry. The results indicate that TPO extends the thermolysis time of FR-PA66, and improves the thermolysis temperature. A three-stage mechanism for the decomposition of FR-PA66 has been proposed in this article. In the first stage, cleavage of P–C bond takes place in FR-PA66, while in the second stage, cleavage of polyamide chain occurs mainly. In the third stage, formation of cyclic compounds proceeds along with the formation of carbonized protective layer on the degraded polymer.     

Synthesis and optical behaviour of hydrogen-bonded liquid crystals based on a chiral pyridine derivative

Three series of cholesteryl-containing supramolecular hydrogen-bonded (H-bonded) liquid crystal (LC) complexes with different number of fluoro-substituent were synthesised and characterised. Cholesteryl isonicotinate as proton acceptor and 4-n-alkoxybenzoic acids with or without fluoro-substituent as proton donor had been mixed in tetrahydrofuran to obtain H-bonded LC complexes. The effect of lateral substitution and the length of terminal chain in the H-bonded precursors on the formation of the supramolecular complexes had been examined. It was found that the introduction of fluoro substituent on the induced mesogens could widen the molecular width and thus reduce the molecular aspect ratio of the complexes, therefore it could lead to compress the formation of the LCs. However, the fluoro substituent played a positive role in enhancing the intermolecular interactions and stabilising the H-bond structure of the complexes. The influence of terminal length on the mesogenic behaviours is also discussed. On increasing the spacer length, the clear point and the thermal range of induced mesophase-like cholesteric phase decreased, and an induced chiral smectic phase began to appear in some complexes with long terminal tails.     

Hydro­gen‐bonded azo­pyridine and succinic acid co‐crystal

In the 1:1 supramolecular adduct of azo­pyridine (AZP) and succinic acid (SA) [systematic name: di‐4‐pyridyl­diazene–succinic acid (1/1)], C₁₀H₈N₄·C₄H₆O₄ or AZP·SA, both components lie on inversion centers. Alternating AZP and SA mol­ecules are linked by O—H·N hydrogen bonds to form a linear chain extending in the [31] direction. Between chains there is a strong pyridyl–azo π–π interaction, with a 3.340 Å separation between the inversion center at the mid‐point of the azo bond and the centroid of the pyridine ring; this interaction results in the formation of sheets.     

基于后向散射模型的蒸汽湿度测量及仿真

为了更加准确地测量出汽轮机末级蒸汽湿度,为锅炉给水量提供依据,促进汽轮机内部除湿技术的发展,采用了后向角散射法的思路设计了湿蒸汽参数测量模型,并对模型所需物理量进行了详细的计算,为后向散射法测量蒸汽湿度的研究提供参考。通过对模型进行仿真模拟以及实验研究,得到了后向散射光光强数据。通过对比仿真模拟数据与实验数据,验证了该模型的可行性与有效性,对光散射法测量蒸汽湿度的实验分析以及工程实践具有重要意义。     

The influence of grafted cellulose nanofibers and postextrusion annealing treatment on selected properties of poly(lactic acid) filaments for 3D printing

l ‐lactide monomers were grafted onto cellulose nanofibers (CNFs) via ring‐opening polymerization, forming poly(lactic acid) grafted cellulose nanofibers (PLA‐g‐CNFs). PLA‐g‐CNFs and pristine PLA were then blended in chloroform and dried to prepare a master batch. PLA‐g‐CNFs/PLA composite filaments targeted for 3D printing were produced by compounding the master batch in PLA matrix and melt extrusion. The as‐extruded composite filaments were subsequently thermal annealed in a conventional oven, and their morphological, thermal, and mechanical properties were evaluated. PLA was successfully grafted on the surface of CNFs as demonstrated by elemental analysis, and the concentration of grafted PLA was estimated to be 33 wt %. The grafted PLA were highly crystallized, contributing to the growth of crystalline regions of PLA matrix. The incorporation of PLA‐g‐CNFs improved storage modulus of the composite filaments in both low temperature glassy state and high temperature rubbery state. Postextrusion annealing treatment led to 28 and 63% increases for tensile modulus and strength of the filaments, respectively. Simulated Young's moduli from the Halpin‐Tsai and Krenchel models were found comparable with the experimental values. The formed composite filaments are suitable for use in 3D printing. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 847–855     

Beam dynamics and RF design of trapezoidal IH-RFQ with low energy spread

Beam dynamics and RF design have been performed of a new type trapezoidal IH-RFQ operating at 104 MHz for acceleration of 14C+ in the framework of RFQ based 14C AMS facility at Peking University. Low energy spread RFQ beam dynamics design was approached by the method of internal discrete bunching. 14C+ will be accelerated from 40 keV to 500 keV with the length of about 1.1 m. The designed transmission efficiency is better than 95% and the energy spread is as low as 0.6%. Combining the beam dynamics design, a trapezoidal IH-RFQ structure was proposed, which can be cooled more easily and has better mechanical performance than traditional RFQ. Electromagnetic field distribution was simulated by using CST Microwave Studio (MWS). The specific shunt impedance and the quality factor were optimized primarily.