溶剂萃取法分离Fe3+、Al3+实验中离子鉴定方法的改进

利用液-液萃取分离Fe3 和Al3 ,最后在滤纸上鉴定它们是否完全分离时,教材中的方法不能准确鉴定出分离后的Fe3 溶液中是否含有Al3 ,而改进的鉴定方法是在原方法的基础上,把滤纸放在氨气上熏蒸,该法能很好地鉴定出Al3 离子。实验现象明显,效果良好。     

光束品质因子M2对非同轴激光雷达探测性能的影响

光束品质因子M2直接影响高斯光束传播特性,光纤口径主要约束激光雷达接收系统的视场角.几何重叠因子是影响激光雷达探测性能的重要参量,其主要受激光束的发射特性、接收系统的结构等影响.通过探讨光束品质因子M2及耦合光纤口径对几何重叠因子的影响,为设计激光雷达发射接收系统,改善激光雷达的探测性能提供了优化方案.数值计算及初步实验表明,光纤的耦合效率与光纤的放置位置及光纤口径有很大的关系;几何重叠因子小于1的探测距离受到M2因子的较大影响且随着M2因子的增大而增大.     

紫外分光光度法测定控释尿素的透膜扩散速率

使用控释氮肥能提高其利用率,减轻环境污染。(包膜型)控释尿素是近几年发展较快的控释氮肥之一。控释尿素透膜扩散速率是其控释性能的一个重要指标。研究表明, 使用对二甲氨基苯甲醛为显色剂,在酸性水溶液介质中显色络合物的最大紫外吸收峰在λ=426 nm处,尿素浓度在7.5～210 μg·mL-1范围内,其浓度与吸光度呈线性关系。据此, 建立了在此紫外波段测定水溶液中尿素的含量来实现控释尿素透膜扩散速率的测定方法, 其回收率为96.1％～103.9％。     

Study on long distance transmission technique of weak photocurrent signal in laser gas sensor

The continuous monitoring of H2S gas concentration is a common problem in natural gas desulfurization process technology.Tunable diode laser absorption spectroscopy(TDLAS)is a preferred technology for continuous monitoring of gas in industrial sites,because of its high selectivity,high sensitivity,and fast response.We discuss the technical solutions of on-line monitoring of H2S in natural gas desulfurization process technology based on TDLAS,and study the security design of monitoring system in inflammable and explosive areas.We also design a weak photocurrent signal converting circuit and perform experiments on transmission characteristics of different distances.The signal-to-noise ratio(SNR)of laser absorption spectrum does not decrease after the 1 500-m transmission.The detection limit is 300 ppb.The system can be operated stably and reliably,and satisfies the need for continuous monitoring of the H2S in natural gas desulfurization process.     

Electronic transport properties of single-wall boron nanotubes

Electronic transport properties of single-wall boron nanotube(BNT) with different chiralities, diameters, some of which are encapsulated with silicon, germanium, and boron nanowires are theoretically studied. The results indicate that the zigzag(3, 3) BNT has more electronic transmission channels than the armchair(5, 0) BNT because of its unique structure distortion. Nanowires encapsulated in the BNT can enhance the conductance of the BNT to some extent by providing a significant electronic transmission channel to the BNT. The effect of the structure of nanowires and the diameter of BNTs on the transport properties has also been discussed. The results of this paper can enrich the knowledge of the electron transport of the BNT and provide theoretical guidance for subsequent experimental study.     

高载量PtNi金属间化合物的氧还原电催化性能

采用改进的多元醇法制备了PtNi(原子比1∶1)质量分数为60%的高金属载量碳载PtNi合金(PtNi/C), 通过在450 ℃下退火处理获得了碳载PtNi金属间化合物氧还原电催化剂. 该催化剂对氧还原的质量比活性和面积比活性分别是商业化Pt/C(JM Pt/C)催化剂的1.66和2.3倍; 并且加速耐久性测试后PtNi金属间化合物催化剂的质量比活性仍与Pt/C的初始性能相当, 耐久性得到了大幅提升. PtNi/C金属间化合物催化剂氧还原活性和稳定性的提高归因于PtNi的有序原子排布结构及催化剂表面零价金属含量的提高.     

氢氧化2，9，16，23-四羧基酞菁合铁(Ⅲ)与硫醇轴配反应

用分光光度法研究了酞菁合铁［Fe(Ⅲ)Pc(COOH)₄OH^-］与β-羟基乙硫醇(HOCH₂CH₂SH)的轴向配位反应热力学，求得了配位数(n)，稳定常数(β_n)及热力学参数Δ_rH⁰_m、Δ_rS⁰_m。用停流法研究了［Fe(Ⅲ)Pc(COOH)₄OH^-］与β-羟基乙硫醇及苯硫酚的轴配反应动力学，讨论了反应机理，求得了预平衡步的平衡常数(K)和速控步的速率常数(k)；研究了温度等诸因素对反应动力学的影响，得到了预平衡的Δ_rH⁰_m、Δ_rS⁰_m和速控步的活化参数Δ^≠H_m、Δ^≠S_m     

Ultraviolet Raman lidar for high-accuracy profiling of aerosol extinction coefficient

An ultraviolet （UV） Raman lidar system at 354.7 nm has been developed for accurately measuring the aerosol extinction profiles. A spectroscopic filter combining a high-spectral-resolution grating with two narrowband mirrors is used to separate the vibrational Raman scattering signal of N2 at a central wavelength of 386.7 nm and the elastic scattering signal at 354.7 nm. The aerosol extinction is derived from the Raman scattering of N2 and the elastic scattering by the use of Raman method and Klett method, respectively. The derived results of aerosol extinction are used to compare the difference of two retrieval methods, and the preliminary experiment shows that the Raman lidar system operated in analog detection mode has the capability of measuring aerosol profiles up to a height of 3 km with a laser energy of 250 mJ and an integration time of 8 min.     

铂纳米棒有序阵列催化电极在被动式直接甲醇燃料电池中的应用

直接甲醇燃料电池(DMFC)具有能量密度高、无需充电、液体燃料添加便捷及环境友好等优点,是新一代便携式移动电源研究热点. DMFC规模应用的主要技术挑战是如何进一步提高电池性能、显著降低成本和可靠延长寿命.催化电极作为 DMFC发电核心和成本的集中体现,其电催化活性和贵金属用量直接影响 DMFC的性能和成本,开发高性能、低成本的催化电极对推进 DMFC实用化进程具有重要意义.特别是在被动式 DMFC中,阴极催化电极不仅需要提高电催化活性和大幅降低贵金属用量,而且还面临内部严重的“水淹”和氧传质受限等问题.近年来,随着纳米技术发展,有序纳米结构已逐渐应用于 DMFC催化电极的构筑中,电池性能得到显著提高.然而,目前的研究主要集中在膜电极纳米有序微孔层、纳米有序改性膜和纳米有序阳极催化电极及其阳极贵金属载量降低等方面,关于阴极催化电极在有序纳米结构以及载量降低等方面的研究相对较少.
　　本文采用模板法直接在微孔层上电沉积定向生长排列有序、直径可控的铂纳米棒阵列,并作为阴极催化电极应用于被动式 DMFC. X射线衍射和透射电镜结果表明,该铂纳米棒结构稳定,表面含有丰富的纳米晶须结构,有利于催化电极比表面积增加和电催化活性提高.不同催化电极上氧还原的极化曲线表明电极性能依下列次序变化：直径为200 nm铂纳米棒阵列电极>100 nm铂纳米棒阵列电极>商业化铂黑催化电极.电池性能表征表明,长度为1–3μm、直径分别为200和100 nm、载量为1.0 mg/cm2的铂纳米棒阵列作为阴极催化电极的 DMFC最大功率密度分别为17.3和12.0 mW/cm2.通过催化电极电化学活性面积和阻抗测试,分析其性能提高的原因可归结于有序排列的铂纳米棒阵列结构提高了电化学活性面积、增强了氧还原电催化活性并促进了阴极氧的传质.     

高纯金属的快速分析-强激光溅射电离飞行时间质谱法

随着现代材料行业的发展,高纯金属纯度分析日趋重要。本研究建立了一种基于强激光溅射电离飞行时间质谱（LAI-TOFMS）检测高纯金属纯度新方法。为消除高价离子和多原子离子等干扰峰的影响,在离子源内引入了氦气。通过分析高纯阴极铜的系列标准样品,建立了其中16种痕量元素的固体直接定量分析方法,在4个动态范围内（10-7 – 10-3 μg/g）的线性相关度优于0.97,检出限低至0.1 μg/g。该方法几乎无需样品处理、分析时间短、操作简便、灵敏度高、谱峰干扰小,可用于高纯金属材料纯度及其痕量杂质的快速分析。