Data Offline Calibration for the BES-Ⅱ TOF System

Data offline calibration and reconstruction for the BES-Ⅱ TOF system are reported in this paper. After applying calibration constants to correct the measured raw data, a the resolution of 180 ps is obtained for the new TOF system. The power of charged particle identification is improved. The momentum for the 3σπ/K separation goes up to 0.93 GeV/c.     

具有纳米结构的铂电极表面的电化学制备及其性能

采用控电位方波氧化还原法和控电流方波氧化还原法分别成功地制备了控电位粗糙铂(CPRPt)和控电流粗糙铂(CCRPt)纳米级铂电极表面.通过考察两类电极表面对甲醇电催化氧化的性能,发现CPRPt和CCRPt纳米级铂电极表面催化氧化甲醇峰值电流密度分别是光滑铂电极的约1.35倍和2.50倍.采用现场拉曼光谱技术考察了两电极表面的表面增强拉曼(SERS)效应,发现两电极表面对吡啶吸附均有较高SERS活性,CPRPt电极表面还对有机小分子的解离吸附的拉曼光谱具有特殊的增强效应.本文初步探讨了两电极表面的SERS机理.     

BER催化还原一些含氮功能基化合物的研究

用强碱性阴离子交换树脂制备了硼氢阴离子交换树脂还原剂(BER),使其在氯化铜等金属化合物的催化下还原一些芳香硝基、氰基、氮氮双键等含氮功能基化合物.还研究了BER的制备条件:如温度、溶剂、不同金属化合物对还原反应的影响,并初步探讨其反应机理.     

Directed Electron Delivery from a Pb-Free Halide Perovskite to a Co(II) Molecular Catalyst Boosts CO2 Photoreduction Coupled with Water Oxidation

The development of high-performance photocatalytic systems for CO₂ reduction is appealing to address energy and environmental issues, while it is challenging to avoid using toxic metals and organic sacrificial reagents. We here immobilize a family of cobalt phthalocyanine catalysts on Pb-free halide perovskite Cs₂AgBiBr₆ nanosheets with delicate control on the anchors of the cobalt catalysts. Among them, the molecular hybrid photocatalyst assembled by carboxyl anchors achieves the optimal performance with an electron consumption rate of 300±13 μmol g⁻¹ h⁻¹ for visible-light-driven CO₂-to-CO conversion coupled with water oxidation to O₂, over 8 times of the unmodified Cs₂AgBiBr₆ (36±8 μmol g⁻¹ h⁻¹), also far surpassing the documented systems (<150 μmol g⁻¹ h⁻¹). Besides the improved intrinsic activity, electrochemical, computational, ex-/in situ X-ray photoelectron and X-ray absorption spectroscopic results indicate that the electrons photogenerated at the Bi atoms of Cs₂AgBiBr₆ can be directionally transferred to the cobalt catalyst via the carboxyl anchors which strongly bind to the Bi atoms, substantially facilitating the interfacial electron transfer kinetics and thereby the photocatalysis.     

表面液晶-垂直腔面发射激光器阵列的热特性

液晶与垂直腔面发射半导体激光器(VCSELs)阵列结合可实现波长可调谐、偏振精确控制等,同时液晶的引入也会改变垂直腔面发射半导体激光器阵列的热特性,本文设计了表面液晶-垂直腔面发射激光器阵列结构,并开展了阵列的热特性实验研究.对比分析了向列相液晶层对VCSEL阵列热特性的影响,实验结果表明,1×1,2×2,3×3三种表面液晶-VCSEL阵列的阈值电流温度变化率最高可降低23.6%,热阻降低26.75%;同时,激光器阵列各发光单元之间的温度均匀性显著提高,出光孔与周围温差小于0.5℃.综上所述,VCSEL阵列中液晶层的引入不仅大大加速激光器阵列单元热量扩散,而且降低了有源区结温,提高了VCSELs激光器阵列热特性,为实现高光束质量的单偏振波长可控VCSEL激光器阵列打下了良好的理论和实验基础.     

不同间隙条件下的叶顶区流动

本文用数值方法研究带有间隙的三维叶栅叶顶区的流动。对于不同大小的间隙及环壁静止与旋转的不同壁面条件,揭示了叶顶区流动的细节。计算结果表明,叶片当地厚度与间隙高度之比过大过小的情形均不易形成叶顶分离涡,相比轮毂静止的情形,轮毂转动时较不易形成叶顶分离涡。     

氧化镁对聚丙烯/聚氯乙烯脱氯行为的影响

对废旧塑料的回收利用是近年来人们一直关注和不断研究的一个重要课题。将废塑料热裂解为燃料油或单体被认为是最具前景的处理方法之一[1]。当含有PVC的废旧塑料裂解时产生氯化氢气体,严重腐蚀设备;同时也会产生含氯的有机化合物,从而使其裂解生成的液体作为燃料使用时会生成有     

吡啶-2-羧酸的Dy(Ⅲ)和Tm(Ⅲ)配合物及其与牛血清白蛋白结合性能

以5-(三氟甲基)吡啶-2-羧酸(Htpc)与DyCl₃·6H₂O、TmCl₃·3H₂O构筑了2种异质同晶的单核配合物[M(tpc)₃(H₂O)₃]·H₂O,其中 M=Dy (1)、Tm (2)。配合物 1 和 2 均为单斜晶系,P2₁/c 空间群,中心金属离子为八配位且形成了轻微扭曲的十二面体构型。温度梯度下的荧光和紫外测试表明,2 种配合物均能与牛血清白蛋白(BSA)发生静态猝灭作用,猝灭常数(K_sv)为 10⁵~10⁶ L·mol^-1。配合物与BSA结合过程的ΔH和ΔS均为正值,说明疏水作用在其中扮演重要的角色。25℃时,2种配合物与BSA结合常数约为10⁴ L·mol^-1,表明二者与BSA的具有中等强度的结合力。     

Lewis Base/Brønsted Acid Co-Catalyzed Asymmetric Thiolation of Alkenes with Acid-Controlled Divergent Regioselectivity

A divergent strategy for the facile preparation of various enantioenriched phenylthio-substituted lactones was developed based on Lewis base/Brønsted acid co-catalyzed thiolation of homoallylic acids. The acid-controlled regiodivergent cyclization (6-endo vs. 5-exo) and acid-mediated stereoselective rearrangement of phenylthio-substituted lactones were explored. Experimental and computational studies were performed to clarify the origins of the regioselectivity and enantioselectivity. The calculation results suggest that C−O and C−S bond formation might occur simultaneously, without formation of a commonly supposed catalyst-coordinated thiiranium ion intermediate and the potential π–π stacking between substrate and SPh as an important factor in the enantio-determining step. Finally, this methodology was applied in the rapid syntheses of the bioactive natural products (+)-ricciocarpin A and (R)-dodecan-4-olide.     

Improved Performance by a Double-Insulator Layer in Organic Thin-Film Transistors

Organic thin film transistors based on pentacene are fabricated by the method of full evaporation. The thickness of insulator film can be controlled accurately, which influences the device operation voltage markedly. Compared to the devices with a single-insulator layer, the electric performance of devices by using a double-insulator as the gate dielectric has good improvement. It is found that the gate leakage current can be reduced over one order of magnitude, and the on-state current can be enhanced over one order of magnitude. The devices with double-insulator layer exhibit field-effect mobility as large as 0.14cm^2/Vs and near the zero threshold voltage. The results demonstrate that using a proper double insulator as the gate dielectrics is an effective method to fabricate OTFTs with high electrical performance.