北京谱仪Ⅲ电磁量能器触发系统的模拟研究

利用北京谱仪Ⅲ探测器模拟和触发系统模拟程序,研究了北京谱仪Ⅲ电磁量能器的触发方案.根据物理目标设计了中性事例触发,巴巴事例判选和带电事例触发的方案,优化了各触发条件的参数,并仔细研究了对本底的排斥能力.研究了一批典型的物理道,给出了它们的触发效率,同时给出了预期的本底触发事例率.     

Result of search for low velocity exotic particles

The L3＋C experiment, taking advantage of the L3 muon magnetic spectrometer, measured the spatial tracks of charged cosmic ray particles to obtain rigidity as well as velocity. One possible low velocity exotic particle is observed. The existing uncertainties are discussed, and the flux upper limit of the low velocity exotic particles from this observation is deduced based on the assumption of a null observation. The result is 6.2×10^-10 cm^-2·s^-1·sr^-1 at 90% confidence level in the velocity range from 0.04c to 0.5c.     

基于MIL⁃53(Al)的碳纳米管复合材料的制备及其用于超级电容器的性能

基于金属有机框架材料MIL?53(Al),制备出多孔碳原位生长碳纳米管(CNTs)的碳复合材料(C?MIL?53(Al)和C?Co@MIL?53(Al))。得益于MIL?53(Al)和CNTs的复合结构以及CoF2的形成,C?Co@MIL?53(Al)复合材料作为超级电容器电极时,在0.5 A·g^-1电流密度下展现出了高比电容(240.1 F·g^-1),并且经过2000次充放电循环后表现出良好的循环稳定性。     

Divergent Total Synthesis of Euphoranginol C,Euphoranginone D,ent-Trachyloban-3β-ol,ent-Trachyloban-3-one,Excoecarin E,and ent-16α-Hydroxy-atisane-3-one

A divergent synthetic approach to biogenetically related diterpenoids such as ent-kauranes, ent-trachylobanes, ent-beyerane, and ent-atisane has been developed. The unified synthetic route involves the De Mayo reaction to rapidly generate the bicyclo[3.2.1]-octane moiety of ent-kaurane. The key reactions also include bioinspired nucleophilic cyclopropanation generating the [3.2.1.0^2,7]-tricyclic core of ent-trachylobane and regioselective cyclopropane fragmentation furnishing ent-beyerane and ent-atisane through the nucleophilic attack and protonation of the cyclopropane ring. This strategy enables the asymmetric total syntheses of six diterpenoids from the commercially available geraniol.     

A Fully Non-fused Ring Acceptor with Planar Backbone and Near-IR Absorption for High Performance Polymer Solar Cells

Fused-ring electron acceptors have made significant progress in recent years, while the development of fully non-fused ring acceptors has been unsatisfactory. Here, two fully non-fused ring acceptors, o-4TBC-2F and m-4TBC-2F, were designed and synthesized. By regulating the location of the hexyloxy chains, o-4TBC-2F formed planar backbones, while m-4TBC-2F displayed a twisted backbone. Additionally, the o-4TBC-2F film showed a markedly red-shifted absorption after thermal annealing, which indicated the formation of J-aggregates. For fabrication of organic solar cells (OSCs), PBDB-T was used as a donor and blended with the two acceptors. The o-4TBC-2F-based blend films displayed higher charge mobilities, lower energy loss and a higher power conversion efficiency (PCE). The optimized devices based on o-4TBC-2F gave a PCE of 10.26 %, which was much higher than those based on m-4TBC-2F at 2.63 %, and it is one of the highest reported PCE values for fully non-fused ring electron acceptors.     

Optimization of SIMS analytical parameters for water content measurement of olivine

Secondary ion mass spectrometry (SIMS) has a wide range of applications in Earth Science research, thanks to its high precision and sensitivity, and its capacity in direct insitu micromeasurement. The technique is operated in ultra-high vacuum (UHV) conditions, especially for the measurement of volatiles such as hydrogen, or the water content in nominally anhydrous minerals (NAMs). To minimize the water background and obtain accurate and precise water contents in NAMs (eg, olivine) critical parameters such as presputtering time, field aperture (FA), dynamic transfer on/off, and primary beam current intensity were investigated for a CAMECA IMS 1280-HR system. When the chamber vacuum reaches approximately 2 × 10⁻⁹ mbar, we set the DTOS OFF, raster size to 50 μm and primary beam current to 5 nA, and used 2000 μm FA and 170-second presputtering time. Consequently, an approximately 1.2 ppmw water background and 3.6 ppmw limit of detection (LOD) were yielded, from analyzing the San Carlos olivine. Meanwhile, the water content and homogeneity of a range of olivine minerals were characterized for potential use as reference materials for SIMS water content measurement. Olivine water content calibration curve was also established by comparing the Fourier transform infrared (FTIR) results with the SIMS-measured ¹⁶O¹H⁻/¹⁶O⁻ ratios. Accuracy and precision of water content measurement were estimated to be better than approximately 10% in this study.     

大环镍(Ⅱ)配合物与扁桃酸的手性识别

外消旋大环镍(Ⅱ)配合物[Ni (rac-L)](ClO₄)₂分别与l-和d-扁桃酸阴离子在乙腈/水溶液中反应,通过手性识别得到六配位的[Ni (_RR-L)(S-Man)]ClO₄(1)和[Ni (SS-L)(R-Man)]ClO₄(2)对映异构体(L=5,5,7,12,12,14-六甲基-1,4,8,11-四氮杂环十四烷,Man=扁桃酸)。当[Ni (rac-L)](ClO₄)₂与dl-扁桃酸阴离子反应时得到一对对映体等量存在的共聚物,其中大环配体中RR和SS构型分别优先与l-和d-Man^- 配位形成外消旋混合物,反应过程中发生了手性识别现象,每颗晶体均为手性对映体。当[Ni (rac-L)](ClO₄)₂分别与结构类似的dl-2-苯基丙酸和dl-托品酸阴离子反应时,分别得到化合物[Ni (rac-L)(dl-PPA)]ClO₄(3)(PPA=2-苯基丙酸)和[Ni (rac-L)(dl-Tro)]ClO₄(4)(Tro=托品酸)。X射线单晶衍射结果表明,4个配合物中Ni (Ⅱ)离子均与折叠大环配体L的4个氮原子和2个来自羧基与羟基的氧原子(1和2),或羧基氧原子(3和4)顺式配位,形成六配位八面体构型。配合物1和2属于一对对映异构体,分别通过[Ni (_RR-L)(S-Man)]⁺和[Ni (SS-L)(R-Man)]⁺分子间氢键作用形成一维之字形链状结构。配合物1和2的单手性特征与圆二色(CD)谱测定结果一致。     

利用Ag@SiO_2纳米粒子等离子体共振增强发光二极管辐射功率的数值研究

金属纳米粒子利用其局域表面等离子体共振效应(LSPR),可以增强附近荧光分子的自发辐射速率,因而在光学传感、光电器件等领域中具有潜在的应用价值.金属纳米粒子的LSPR与其自身的材料、形状、尺寸以及周围环境介质密切相关,这影响着纳米粒子在具体器件中的应用.本文利用三维时域有限差分法,研究了相同体积的球形、椭球形、立方形与三棱柱形银纳米粒子对薄膜发光二极管辐射功率的影响;计算了不同形状银纳米粒子对偶极子光源辐射功率和薄膜器件光出射强度的增强,并结合LSPR效应讨论了辐射功率变化的物理机理.研究结果表明:银纳米粒子自身形状尖锐程度的增加有利于提高LSPR的共振强度;同时纳米粒子的形状影响了LSPR共振电场与薄膜器件中偶极子辐射电场之间的耦合作用,其中立方形纳米粒子因为能实现最强的耦合作用而对器件的辐射功率增强最大.在此基础上进一步讨论了不同薄膜材料对LSPR共振及光源辐射功率的影响,发现较高的材料折射率有利于增强金属纳米粒子的LSPR与器件的耦合作用,从而改善发光二极管性能.     

领结形中空表面等离子体波导的传输特性

设计了一种领结形中空表面等离子体波导.采用频域有限差分法,对这种波导所支持的基模的能流密度分布、有效折射率、传播长度和模式面积随几何结构参数和工作波长的依赖关系进行了分析.结果表明,沿纵向的能流主要分布在两个上下突起所形成的中间区域.通过调整几何参数及工作波长,可以调节模式的有效折射率、传播长度和模式面积.在工作波长确定的条件下,有效折射率随突起半径的增大呈减小趋势,而传播长度和模式面积则随着突起半径的增大呈增大趋势,四个角上的圆弧半径对波导的传输特性有微调作用,左右扇形区域的半径对波导的传输特性有较明显 关键词： 集成光学 光波导 表面等离子体波导     

Convergence of the viscosity solution of non-autonomous Hamilton-Jacobi equations

In this paper,we investigate the non-autonomous Hamilton-Jacobi equation ■ where H is 1-periodic with respect to t and M is a compact Riemannian manifold without boundary.We obtain the viscosity solution denoted by T_(t_0)~tφ(x) and show T_(t_0)~tφ(x) converges uniformly to a time-periodic viscosity solution u~*(x,t) of ?_tu+H(t,x,?_xu,u)=0.