脉冲电晕放电脱除NO化学反应动力学过程

采用非接触的色散荧光发射光谱和时间分辨光谱方法,在大气压条件下,对脉冲电晕放电脱除NO的化学反应动力学过程进行了实验研究。在该研究中,首先利用色散荧光发射光谱方法,得到纯NO气体脉冲电晕放电中各活性粒子的色散荧光谱,并对其进行归属,确定了各活性粒子的灵敏指纹跃迁谱线;在此基础上,通过测量NO气体放电过程中所产生的N+,O,N₂及NO分子的灵敏指纹跃迁谱线的时间行为特性,研究脉冲电晕放电脱除NO的化学反应机理。实验结果表明：在脉冲电晕放电过程中,NO分子首先与高能电子发生非弹性电离碰撞,变成NO+离子,随后NO+离子发生解离反应,形成N+离子和O原子;N+离子在向阴极运动过程中与电子碰撞结合成激发态N原子,继而和其他激发态N原子结合成为激发态N₂;而O原子则应与其它O原子结合成为O₂。由此建立了大气压条件下纯NO气体脉冲电晕放电脱除NO的化学反应动力学模型。     

一种实验教学用蒸发结晶装置的设计

针对目前蒸发结晶实验教学的需要,以实验室常用玻璃器材为主,设计了一种蒸发结晶装置。该装置包括数显加热搅拌装置、蒸发瓶、滴液装置、H型管、套管式换热器、冷凝液接收装置、连接装置和原料液储罐等8个部分,结构简单、占用空间小。并以硫酸铜溶液的蒸发结晶过程为例,对其使用方法进行了研究。通过外形的设计,可实现装置安装时长在15 min内,用时短,拆卸方便;通过控制原料液浓度和流速,实现对晶体的生长速度和形状的调控;原料液可循环使用,原料节约;玻璃器材为主,原理展示清晰;以硫酸铜水溶液为原料液,颜色鲜艳,便于演示。该装置能较好地满足高校工程类专业实验教学的需求。     

Y1-xRxBa2Cu3O7—δ体系（R=Eu、Gd）的正电子寿命和超导性研究

本文报道了对Y1-xRxBa2Cu3O7-δ（R=Eu、Gd）两个系列样品的超导电性研究结果．首先，发现随着Eu、Gd掺杂量x的增加，Y1-x]EuxBa2Cu3O7-δ和Y1-xGdxBa2Cu3O7-δ的晶胞体积均随之增大．但所有样品均保持与Y-123样品相同的单相正交结构；正电子平均寿命实验结果表明Cu—O链处局域电子密度ne随Eu、Gd掺杂浓度x的增加而减小．说明Eu、Gd对Y位的替代引起晶胞结构参量的变化不汉改变了Y位的电子密度．同时也影响了Cu-O链周围的电子密度分布；超导转变温度Tc随Eu、Gd掺杂浓度x增加而略有增加，反映了Eu、Gd掺杂虽然改变了体系的局域电子结构．但没有破坏超导所需的Cu-O链与CuO2面之间的耦合：Y位掺杂体系的超导电性与掺杂离子的磁性无关，而与掺杂离子的半径有关．     

EFFECTS OF BANDGAP SHRINKAGE IN FEMTOSECOND ABSORPTION SATURATION MEASUREMENTS OF GaAs FILM

Using CPM dye laser and self-mode-locked Ti sapphire laser as pump-probe optical sources, the effects of bandfilling and bandgap shrinkage on the femtosecond absorption saturation spectra of GaAs film have been studied, For exciting photon energy of 1.97eV and carrier density of 1×10¹⁸cm^-3, an optical-induced absorption increase is observed and is attributed to bandgap shrinkage, The dependence of the absorption coefficient change on the carrier temperature and the carrier densities is discussed.     

RELAXATION DYNAMICS OF PHOTOINDUCED EXCITON BLEACHING IN POLYMERS

Presented in this paper are systematic studies of photoiuduced exciton bleaching dynamics in the polymers with nondegenerate ground state, such as polydiacetylene, polythiophene and polyaniline. From a three-level model, the photoexcitation and relaxation of the exciton bleaching in the polymers are simulated. The results show that the exciton bleaching decay is composed of two components, the fast component and the slow component. For the fast component, the speed of exciton bleaching decay depends on the way in which the excitons relax. When the relaxation of the exciton to the ground state is dominant, the polymers exhibit an ultrafast initial bleaching relaxation; when the relaxation of the exciton to the self-trapped exciton state is dominant, the polymers exhibit a slower initial bleaching relaxation than that in the former case, For the slow component, the exciton bleaching decay is due to the relaxation of the self-trapped excitons to the ground state. Using femtosecond time-resolved pump-probe technology, we measured the relaxation dynamics of the photoinduced exciton bleaching in the emeraldine base form of polyaniline. Fitting the experimental data to the theoretical model indicates that the fast component arises from the relaxation of excitons to the ground state (～100fs) and the slow component arises from the relaxation of self-trapped excitons to the ground state (～30 ps).     

回旋管磁场电流调节器的改进

一、引言 最近,用电子回旋共振加热(ECRH)产生热电子等离子体引起了人们很大兴趣。为开展ECRH在聚变装置的应用研究,我们在一个简单磁镜MM-2中,用频率15千兆赫回旋管建立热电子等离子体,并开展了一系列热电子环物理实验研究。在该装置实验中,我们发现,回旋管正常工作的关键是它的主磁场电源的稳定度。它要求电源输出500A时,电流稳定度优于0.05％。最早该电源用28只三极管并联作为电流调节器,由于管子参数分散性大,均流和     

4-羟基异维A酸(4-N-茄尼基氨基苯酚)酯的合成

以异维A酸和茄尼醇为原料合成了4-羟基异维A酸(4-N-茄尼基氨基苯酚)酯,其结构经1H NMR,13C NMR,IR和MS表征.     

激光烧蚀La-Ca-Mn-O反应产物的角分辨和时间分辨质谱研究

研究了 5 32nm脉冲激光烧蚀La₂-O₃-CaO-MnO₂ 混合氧化物的反应 .在较高的激光能量密度下 ,烧蚀反应生成了高平动能的La ,Ca和Mn的离子、原子以及多种不同价态的金属氧化物 .由时间分辨质谱测得的飞行时间谱可用带质心速度的Maxwell-Boltzmann分布拟合 ,并由此得出Mn⁺离子的最可几平动能为 6 34eV ,Mn原子的最可几平动能为 0 .43eV .对烧蚀产物的角分布测定表明 ,Mn⁺离子的角分布可用cosⁿθ描述 ,而Mn原子的角分布遵循acosθ + ( 1 -a)cosⁿθ公式 .同时 ,对La-Ca-Mn-O的激光烧蚀反应机理进行了讨论 .     

Enhanced Production of Crude Violacein from Glucose in <Emphasis Type="Italic">Escherichia coli</Emphasis> by Overexpression of Rate-Limiting Key Enzyme(S) Involved in Violacein Biosynthesis

Cadaverine is used for the synthesis of the novel bio-polyamides 54, 56, and 510. Here, we examine the feasibility of using a lysine decarboxylase (LdcC) from Escherichia coli for high-level production of cadaverine. After sequential optimization of whole-cell biotransformation conditions, recombinant E. coli-overexpressing LdcC (EcLdcC) could produce 1.0 M cadaverine from 1.2 M crude l-lysine solution after 9 h. EcLdcC retained a higher cadaverine yield after being reused 10 times at acidic and alkaline pH values than that of a recombinant E. coli strain overexpressing an inducible lysine decarboxylase (CadA), a conventional cadaverine producer (90 vs. 51% at pH 6 and 55 vs. 15% at pH 8). This study reveals that EcLdcC is a promising whole-cell biocatalyst for the bio-based production of cadaverine from industrial grade l-lysine in comparison to EcCadA.     

Ho3+/Yb3+共掺ZnO-Al2O3-GeO2-SiO2玻璃陶瓷的制备和上转换发光性质

综合ZnO-Al_2O_3-SiO_2系和锗酸盐玻璃陶瓷的优点,采用熔融-晶化法首次制备了Ho~(3+)/Yb~(3+)共掺以ZnAl_2O_4为主晶相的ZnO-Al_2O_3-GeO_2-SiO_2系玻璃陶瓷。因[GeO_4]四面体和[SiO_4]四面体都是玻璃网络形成体,讨论了GeO_2取代SiO_2对玻璃陶瓷样品硬度及发光性能的影响,最终确定GeO_2的取代量为10.55%(w/w)时,玻璃陶瓷综合性能最佳。在980 nm泵浦光的激发下,发现强的绿色(546 nm)和弱的红色(650 nm)上转换发光,并研究了不同Ho~(3+)/Yb~(3+)掺杂比对样品上转换发光的影响,最终结果表明当Ho~(3+)/Yb~(3+)掺杂比为1∶11(n/n)时样品荧光强度最强,在绿色上转换发光材料方面具有潜在的应用。