2,4-二甲基吡咯-3,5-二羧酸二乙酯的合成——推荐一个大学有机化学实验

采用Knorr吡咯合成法，以乙酰乙酸乙酯和亚硝酸钠为原料，在醋酸和锌粉作用下采用“一锅法”得到2,4-二甲基吡咯-3,5-二羧酸二乙酯。本实验涉及到控温、回流、重结晶、熔点测定、红外光谱及核磁共振等实验操作和分析检测方法。该实验原料简单易得、产物收率高，结合波谱解析方法，可以培养和提高学生合成实验的能力，加强学生对杂环合成和波谱解析的理解与分析。     

Adsorption of thorium(IV) on magnetic multi-walled carbon nanotubes

The influences of pH, contact time, solid-liquid ratio, temperature and C60(C(COOH)2)n on Th(IV) adsorption onto the magnetic multi-walled carbon nanotubes(MMWCNTs) were studied by batch technique. The dynamic process showed that the adsorption of Th(IV) onto MMWCNTs could reach equilibrium in 40 h and matched the pseudo-second-order kinetics model. The adsorption of Th(IV) onto MMWCNTs was significantly dependent on pH values, the adsorption ratio increased markedly at pH 3.0–5.0, and then maintained a steady state as pH values increased. At low pH, different C60(C(COOH)2)n content could enhance the adsorption content of Th(IV) onto MMWCNTs, but restrained it at higher pH. Through simulating the adsorption isotherms by Langmuir, Freundlich and Dubini-Radushkevich models, it could be seen respectively that the adsorption pattern of Th(IV) onto MMWCNTs was mainly surface complexation, and that the adsorption process was endothermic and irreversible.     

光谱法锌离子检测系统的研究

采取标准锌显色剂与锌发生显色反应，生成不溶于水的絮状络合物。用光谱仪测它的吸光度，研究其特征谱与吸光度的特点，建立其浓度与特征波长吸光度间的数学模型。本文所采用的显色剂主要与锌、铜、镉、镍四种离子发生络合反应。因此分别探索了四种离子高浓度以及低浓度时显色反应的吸光度，最终通过得到锌离子浓度与吸光度的关系式以及锌离子浓度与四波长下四种离子混合溶液显色后的吸光度的关系式，给出了锌离子的吸光度与总吸光度的关系式。显色反应能否满足分光光度法的要求，主要与显色剂的性质有关，同时显色反应的条件也至关重要。因为在显色反应过程中，主要是锌离子与锌显色剂发生络合反应形成络离子，进而形成絮状络合物。络离子一般比较稳定，但在水溶液中也存在着电离平衡，也就是说当显色条件发生变化时，既有可能形成络离子，也有可能发生络离子的分解，从而影响络合反应的程度。显色条件包括显色剂用量、pH值、反应温度、显色时间、待测溶液的盐度以及浊度等。重点研究待测溶液的盐度对锌离子浓度测量值的影响，并通过实验给出影响规律以及校正模型。     

Nd∶YVO4/Nd∶GdVO4双波长激光器的功率均衡实验研究

实验研究了Nd∶YVO4/Nd∶GdVO4双波长激光器在不同抽运功率条件下,通过调节热沉温度达到功率均衡时的输出特性.实验结果表明:对于Nd∶YVO4/Nd∶GdVO4双波长激光器,当提高抽运功率,需要重新降低热沉温度达到功率均衡输出,降温幅度与抽运功率增加之比为11.23℃/W.与此同时,随着抽运功率和热沉温度的变化,双波长激光器的中心波长会出现小幅度的漂移,左峰波长随抽运功率增加的蓝移速率为0.056 nm/W,右峰波长随抽运功率增加的蓝移速率为0.054 nm/W.实验还发现功率均衡条件下激光器的输出总功率随抽运功率的增加而增加,拟合斜效率为8.7%,当抽运功率为5.58 W时,输出最大总功率达到115.7 mW.     

光伏太阳能电池生产过程中的污染问题

日益壮大的光伏产业正在为人类发展作出积极的贡献.采用光伏发电来代替传统的发电技术,将会减少89%的空气污染.然而,在这个倡导绿色环境的时代,光伏器件生产引起的环境、健康和安全（EHS）问题也日益引起社会各界的广泛关注.认清光伏产品在生产过程中污染的真相对维持光伏产业的可持续发展有着相当重要的意义.本文综述了常见太阳能电池的EHS问题,并提出了可以减少污染的有效途径;采用生命周期评估（LCA）方法进一步比较了各种太阳能电池生产过程中污染物的排放量数据.     

Stereospecific radical polymerization of optically active (S)-N-(2-hydroxy-1-phenylethyl) methacrylamide catalyzed by Lewis acids

The effects of Lewis acids, namely, rare earth metal trifluoromethanesulfonates, on the radical polymerization of (S)-N-(2-hydroxy-1-phenylethyl) methacrylamide were examined under various conditions. In the absence of Lewis acids, syndiotactic-rich polymers (r = 84%) were obtained, whereas in the presence of a catalytic amount of Lewis acids, the polymerization proceeded in an isotactic-specific manner (m up to 64%). Polymerization solvents strongly influenced the effect of the Lewis acids. The polymerization in n-butyl alcohol showed the highest isotactic selectivity, whereas the polymerization in DMSO showed no isotacticity-enhancing effect. Further increases in the Lewis acid concentration and the polymerization temperature did not produce clear effects on the tacticity of the polymers. The interaction between the monomer and Lewis acids was investigated, and the plausible mechanism of stereocontrol in the radical polymerization of (S)-HPEMA was analyzed based on the Lewis acid-monomer interaction.     

N-Doped Carbon Nanofibers Encapsulating CoO@Co9S8 Nanoparticles: Preparation from S-Rich Co32 Coordination Cluster Precursors by Electrospinning and Application for Superior Li-ion Storage

Thiacalixarene-supported Co₃₂nanoclusters encapsulated in polyacrylonitrile nanofibers(Co₃₂@PAN-NFs) by electrospinning have been utilized as precursors to fabricate N-doped CoO@Co₉S₈ carbon nanofibers(CoO@Co₉S₈@CNFs) for superior Li-ion storage. The S-rich Co₃₂ clusters capped by organic sheets afforded the well dispersed cobalt oxide/sulfide nanoparticles embedded in carbon nanofiber composites by direct calcination. The N-doped CoO@Co₉S₈@CNFs nanocomposites have been utilized as anode materials for lithium ion battery with the reversible capabilities being of 1051.8, 967.6, 894.7, 782.7, 669.5 and 525.4 mA·h/g at 0.1, 0.2, 0.5, 1, 2 and 3 A/g, respectively. The CoO@Co₉S₈@CNFs also showed a relatively high stable capacity of 551.7 mA·h/g at the current density of 1 A/g after 200 cycles of rate experiments. The as-obtained N-doped CoO@Co₉S₈@CNFs nanocomposites exhibited superior reversible capacity, rate performance, Coulomb efficiency(74.5% vs. 63.9%) and cyclic stability comparing with the CoO@Co₉S₈@C derived from simple annealing of Co₃₂ templates.     

微弱日盲紫外电晕自动实时检测方法

针对目前商用日盲紫外/可见光双谱段电晕探测仪对故障的判定效率低且容易受噪声干扰问题,本文提出了一种微弱日盲紫外电晕自动实时检测方法。在分析电晕目标和噪声时间域统计特性的基础上,该方法利用电晕目标在时间域连续的特点,首先完成灰度图像二值化、形态学膨胀等预处理,其次将N帧连续图像累加后阈值化,最后进行特征提取,获取电晕位置、面积等特征信息,实现电晕的自动实时检测。在完成设备辐射标定的基础上,可立即回溯得到故障的光子计数参考值。建立了该方法的探测概率、虚警率数学模型。将其在高速数字处理平台TMS320DM642上实现并输入测试视频,结果表明:在典型参数情况下该方法单次检测虚警概率为2.85×10^-5,处理时间小于120 ms,可实现微弱日盲紫外电晕的实时检测。