充氢镍箔放氢过程的XRD与EXAFS研究

本文通过带有EXAFS附件的X射线衍射仪在实验室用XRD和EXAFS两种方法完成了对充氢镍箔放氢过程的研究,测定了放氢过程中样品中NiH相含量随释氢时间的变化,XRD和EXAFS的结果是一致的,均呈指数规律下降。实验还确定了NiH相中镍和氢的原子比,说明了氢在点阵中的位置,证明实验室EXAFS装置适合这类问题的研究。 关键词：     

PIP法制备Cf/SiC复合材料过程中碳纤维的化学损伤

对先驱体聚碳硅烷浸渍裂解工艺(PIP)制备Cf/SiC复合材料过程中碳纤维损伤严重的问题, 系统地分析了在Cf/SiC复合材料制备过程中先驱体裂解对碳纤维的化学损伤. 研究结果表明, PIP工艺中碳纤维的化学损伤包括界面反应和基体向碳纤维内部的扩散反应. 其中聚碳硅烷(PCS)中的活性基团和碳纤维的化学反应并不严重, 而微量的氧气和杂质对碳纤维的化学损伤影响很大; 基体中硅等元素可向碳纤维内部扩散, 随着高温处理时间的延长而加深, 并形成脆性的界面层, 使碳纤维截面积减小. 在第一周期浸渍裂解过程中, 先驱体对碳纤维的化学损伤很少, 在后续周期中, 随着基体致密度的提高, 碳纤维的化学损伤有所增加.      

Bi2MoO6纳米薄膜的制备及其光电性能

采用非晶态配合物法在ITO导电玻璃上制备了Bi2MoO6薄膜. 采用扫描电子显微镜(SEM)、X射线衍射(XRD)、激光拉曼光谱(LRS)、紫外-可见漫反射谱(DRS)、光电流响应谱、光电转换量子效率(IPCE)等技术研究了Bi2MoO6薄膜的制备工艺、形貌、结构与薄膜光电性能的关系. 结果表明, 500 ℃、1 h焙烧后的Bi2MoO6薄膜为γ-Bi2MoO6晶相, 沿(131)晶面方向生长, 薄膜厚度约为69 nm. 随着焙烧温度的升高和焙烧时间的延长, Bi2MoO6薄膜的平均颗粒度增大, 并且在525 ℃焙烧出现β-Bi2MoO6和γ’-Bi2MoO6晶相. Bi2MoO6薄膜具有可见光响应活性, 在可见光照射下可以产生光电流, 优化条件下的Bi2MoO6薄膜在400 nm的光电转换量子效率可以达到2.14%. 薄膜的光电响应和光电转换量子效率受薄膜形貌及结晶状态影响, 可以通过控制薄膜的制备条件来提高薄膜的光电转换量子效率.     

Effect of Mo loading on transesterification activities of MoO3/γ-Al2O3 catalysts prepared by conventional and slurry impregnation methods

Summary The effect of Mo loadings and preparation methods, slurry and conventional impregnation, on the performances of alumina-supported MoO₃ catalysts in transesterification of dimethyl oxalate (DMO) with phenol was investigated. Slurry prepared MoO₃/-Al₂O₃ catalyst exhibited higher activity and dispersion capacity than conventional one. Slurry MoO₃/water was used instead of an ammonium heptamolybdate solution. Highly dispersed amorphous Mo catalysts were obtained, closely related to the catalytic activities without calcination, waste solutions, and calcining nitrogenous gases.     

SFC引出静电偏转板高压放电的研究

根据SFC引出静电偏转板的特殊工作环境和运行中发生的现象， 对其高压放电机理进行了深入的研究和大量的电磁场计算。 计算结果表明， 在电场和磁场的共同作用下， 盖板损伤的发生部位与实际运行中的打火痕迹完全符合。 最后阐述了SFC引出偏转板的高压放电过程， 并对其改进措施进行了研究。Due to the special working conditions of the SFC extraction deflector, the breakdown of the deflector is a serious problem. Based on the electromagnetic field calculations and the analysis of electrons and ions in the field, the breakdown mechanism was investigated. The calculated results about the electron hitting spots on the liners are consistent with the observed ones in the operation. At last, an improvement method of the deflector is suggested by using aluminum cathode and combined liners     

超高效液相色谱-串联质谱法同时测定食品级聚苯乙烯和聚乙烯色母粒中33种初级芳香胺

建立了超高效液相色谱-三重四极杆质谱(UPLC-MS/MS)同时测定食品级聚苯乙烯(PS)和聚乙烯(PE)色母粒中33种初级芳香胺(PAAs)的检测方法。PS色母粒用二氯甲烷溶解,超声提取后加入甲醇沉淀,并将提取液过石墨化碳固相萃取柱净化;PE色母粒用二氯甲烷超声溶胀提取;将PS色母粒过柱液和PE色母粒提取液浓缩,浓缩液用甲醇-水(1:9, v/v)定容至2 mL, 0.22 μm膜过滤后上机检测。采用BEH Phenyl色谱柱(100 mm×2.1 mm, 1.7 μm),以0.07%(v/v)甲酸甲醇溶液-水(1:9, v/v)为流动相,梯度洗脱分离,UPLC-MS/MS多反应监测(MRM)模式检测,同位素内标法定量。优化了色谱分离条件、质谱碎裂电压、碰撞能量等,并考察了提取时间、提取溶剂、浓缩方式等对回收率的影响。33种PAAs的方法检出限为6~10 μg/kg,定量限为20~30 μg/kg, 2种不同基质样品在20、100、200 μg/kg等3个添加水平的平均回收率为61.3%~119.8%,相对标准偏差(RSD)为1.4%~14.8%。本方法操作简便、快速、准确、灵敏度高,能满足相关测定要求。     

Ar对微波等离子体CVD单晶金刚石生长的影响

采用自主研发的5 kW不锈钢谐振腔式MPCVD设备,在Ar/H2/CH4气氛下,保持总气压与CH4气流量不变,研究了不同Ar/H2比例对单晶金刚石生长速度和晶体质量的影响.通过拉曼光谱与高分辨率XRD摇摆曲线,从生长速度与生长质量两点对所得样品进行分析.结果表明,适量Ar的存在能够显著提高单晶金刚石的生长速度,并且不损害金刚石的晶体质量.当Ar/H2=30;时,生长速度最高,为35 μm/h.随着Ar/H2比例的进一步增加,单晶金刚石的结晶质量会有所下降,Ar/H2比例过高则会严重破坏单晶金刚石的生长.     

同轴静电纺丝法制备TiN@MnO纤维及其电化学性能研究

本文以钛酸四丁酯和乙酰丙酮锰为起始原料,聚乙烯吡咯烷酮(PVP)为分散剂分别配制高分子溶液. 采用同轴静电纺丝法制备了TiN@MnO前驱体,并经氨气处理得到了具有芯-壳结构的TiN@MnO同轴纤维. 采用X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)、X射线能量色散谱(EDX)和物理吸附仪分析、观察和表征TiN@MnO同轴结构纤维,其比表面积达16 m2?g-1. 循环伏安曲线测试(CV)表明,在20 mV?s-1倍率下,TiN@MnO同轴纤维电极比电容保持率为2 mV?s-1倍率下的81%,充分说明TiN和MnO两种组分的协同效应提高了电极的倍率性能.     

帽状金纳米结构的制备、表征及表面增强拉曼散射活性

采用真空离子溅射法在自组装的单层阵列二氧化硅纳米粒子表面沉积金薄膜, 制备了以SiO₂为核的帽状金纳米结构. 用透射电镜、扫描电镜、原子力显微镜、X 射线衍射仪和紫外-可见-近红外分光光度计对样品的表面形貌、结构及光学性质进行了表征. 以亚甲基蓝作为探针分子, 对金纳米帽的表面增强拉曼散射活性进行了研究, 结果显示, 吸附在金纳米帽上的分子拉曼散射信号得到显著增强, 增强因子达到10⁷数量级. 该基底在超灵敏生物和化学检测方面具有潜在的应用前景.     

Design of the IMP microbeam irradiation system for 100 MeV/u heavy ions

A state-of-the-art high energy heavy ion microbeam irradiation system is constructed at the Institute of Modern Physics of the Chinese Academy of Sciences. This microbeam system operates in both full current intensity mode and single ion mode. It delivers a predefined number of ions to pre-selected targets for research in biology and material science. The characteristic of this microbeam system is high energy and vertical irradiation. A quadrupole focusing system, in combination with a series of slits, has been designed to optimize the spatial resolution. A symmetrically achromatic system leads the beam downwards and serves simulta-neously as an energy analyzer. A high gradient quadrupole triplet finally focuses a C6+ ion beam to 1 μm in the vacuum chamber within the energy range from 10 MeV/u to 100 MeV/u. In this paper, the IMP microbeam system is described in detail. A systematic investigation of the ion beam optics of this microbeam system is presented together with the associated aberrations. Comparison is made between the IMP microbeam system and the other existing systems to further discuss the performance of this microbeam. Then the optimized initial beam parameters are given for high resolution and high hitting efficiency. At last, the experiment platform is briefly introduced.