脑电信号的标度分析及其在睡眠状态区分中的应用

脑电信号具有长程幂律相关性及多重分形的标度特性,并随生理病理状态改变.本文首次针对睡眠脑电信号应用单重分形去趋势波动分析(detrended fluctuation analysis,简记为DFA)方法与多重分形奇异谱对睡眠脑电信号的标度特征进行系统的对比研究.发现DFA标度指数α对于不同导联和样本组间的差异较为敏感,随睡眠状态的变化不规律;而多重分形奇异强度区间Δα随睡眠状态的变化更为规律,睡眠Ⅰ期至Ⅳ期不断增大,并且导联间差异和样本组间差异均较小.多重分形Δα参数更适合作为判定睡眠状态的定量参数.     

High performance of semiconductor optical amplifier available for cold atom physics research

We present a novel design of a compact, stable, and easy-adjustable semiconductor optical amplifier （SOA） system. This SOA system is capable of providing up to 560-roW laser power at the wavelength of 852 nm. For the continuous-wave （CW） seeding laser, the amplification gain can reach 18 dB. We add amplitude modulation onto the CW laser and measure the modulation amplification between seeding and output laser. The amplification gain remains constant within the frequency range from 10 Hz to 1 MHz. The whole system could work in ultra-stable condition： for CW seeding laser, the fluctuation of output power is less than 0.33% in several hours.     

复合微球的制备、性能及应用

本文综述了复合微球的制备、性能及其应用，并对其发展趋势作了展望．     

生石灰颗粒中温脱硫过程数值计算

本文采用晶粒模型对中温条件下单颗粒石灰石脱硫过程进行数值模拟。利用已有文献数据、电子显微镜及TGA实验数据确定模型中化学反应动力学以及物性参数。计算结果与TGA实验结果符合较好,表明脱硫模型可直接应用于中温条件下石灰石脱硫过程的数值预报与分析。     

玻色-爱因斯坦凝聚特性及其应用

本文介绍了北京大学建立的玻色-爱因斯坦凝聚实验平台，实现了玻色-爱因斯坦凝聚（图1），获得了原子数为五十万个，温度为50纳开尔文的玻色凝聚体。在此基础上我们精密测量了玻色-爱因斯坦凝聚的相变温度，还利用玻色-爱因斯坦凝聚实验平台通过马越让那跃迁获得了可控的多量子态玻色爱因斯坦凝聚体。并利用四种方法获得了原子激光（图2），其中有三种方法是国际上第一次使用。另外，我们提出了将玻色一爱因斯坦凝聚转入Magic光晶格阱，实现精度优于10^-17的新型原子钟的设想。     

环氧氯丙烷修饰的对位和间位芳纶涂覆剂研究

制备了具有环氧丙基侧链的对位芳纶(PPTA-ECH)和间位芳纶(PMIA-ECH),并将其用做对位芳纶(PPTA)织物/环氧树脂复合材料中PPTA织物的涂覆剂。采用场发射扫描电子显微镜(FE-SEM)及XPS等方法对PPTA织物表面的PPTA-ECH涂层结构进行了表征。考察了PPTA-ECH和PMIA-ECH涂覆的PPTA织物/环氧树脂复合材料的层间剪切强度和面内剪切强度,并与未经涂覆的PPTA织物复合材料的性能作比较。结果表明,PPTA-ECH和PMIA-ECH可显著改善PPTA织物和环氧树脂之间的界面性能。涂覆了PPTA-ECH及PMIA-ECH的PPTA织物/环氧树脂复合材料的层间剪切强度(ILSS)比未经涂覆的复合材料分别提高了26.20%和14.76%,面内剪切强度(ISS)分别提高了26.98%和11.86%。由于PPTA-ECH对PPTA纤维具有更强的亲和能力,因此PPTA-ECH在层间剪切强度和面内剪切强度方面的增强效果均优于PMIA-ECH。对PPTA-ECH在PPTA纤维表面铺展与吸附及对复合材料的增强机理也进行了初步探讨。作为新型涂覆剂,PPTA-ECH在对位芳纶复合材料的开发应用方面具有潜在的应用前景。     

微波消解-ICP-MS法测定肺癌患者肺组织中33种元素

建立了冷冻干燥微波消解ICP-MS法测定肺癌患者肺组织中33种元素的方法。样品经真空冷冻干燥,采用纯化硝酸-过氧化氢体系微波消解,稀释定容后用ICP-MS对溶液进行元素的测定,在优化仪器工作参数后,以铑(Rh)和铼(Re)双内标进行校正。测定结果表明,元素检出限为0.01～0.45 ng·mL-1,测定了国家标准物质GBW(E)080193牛肝中的元素,测定值与标准值或参考值一致,元素精密度(RSD)为2.1%～14.3%,回收率为90.1%～117.5%。用该法测定了6例肺癌患者的肺癌、癌旁和正常组织中33种元素的含量。所建立的方法快速、简便、准确,适于肺组织等生物样品中多种元素的测定。     

珠状酚醛系氨基膦酸树脂的制备及其螯合性能

本文采用反相县浮聚合技术,以苯酚、甲醛、乙二胺为起始原料,一步反应制得珠状凝胶型、大孔型胺基树脂,进一步膦酸化后得到珠状氨基膦酸螯合树脂,小球表面光滑,颗粒均匀,对Ｃａ＾２＋和Ｃｕ＾２＋螯合容量分别达到１．３６ｍｍｏｌ／ｇ和２．３１ｍｍｏｌ／ｇ。氨基膦酸树脂对Ｃａ＾２＋的吸附可用Ｆｒｅｕｎｄｌｉｃｈ吸附等温式加以描述,Ｆｒｅｕｎｄｌｉｃｈ参数ｎ＝１．７６９,线性回归方程相关系数γ＝０．９９５８。     

基于条件熵扩维的多变量混沌时间序列相空间重构

提出一种多变量混沌时间序列相空间重构的条件熵扩维方法.首先使用互信息法求解每个变量的时间延迟,其次按条件熵最大原则逐步扩展相空间的嵌入维数,使得重构坐标从低维到高维的转换保持较强的独立性,最终的重构相空间具有较低的冗余度,为多变量时间序列的预测构造了有效的模型输入向量.通过对几个经典多变量混沌时间序列进行数值实验,结果表明该方法比单变量预测和已有多变量预测方法具有更好的预测效果,说明了该重构方法的有效性. 关键词： 多变量混沌时间序列 相空间重构 条件熵 神经网络预测     

Generation and expansion of laser-induced plasma as a spectroscopic emission source

Laser-induced plasma represents today a widespread spectroscopic emission source. It can be easily generated using compact and reliable nanosecond pulsed laser on a large variety of materials. Its application for spectrochemical analysis for example with laser-induced breakdown spectroscopy (LIBS) has become so popular that one tends to forget the complex physical and chemical processes leading to its generation and governing its evolution. The purpose of this review article is to summarize the backgrounds necessary to understand and describe the laser-induced plasma from its generation to its expansion into the ambient gas. The objective is not to go into the details of each process; there are numerous specialized papers and books for that in the literature. The goal here is to gather in a same paper the essential understanding elements needed to describe laser-induced plasma as results from a complex process. These elements can be dispersed in several related but independent fields such as laser-matter interaction, laser ablation of material, optical and thermodynamic properties of hot and ionized gas, or plasma propagation in a background gas. We believe that presenting the ensemble of understanding elements of laser-induced plasma in a comprehensive way and in limited pages of this paper will be helpful for further development and optimized use of the LIBS technique. Experimental results obtained in our laboratory are used to illustrate the studied physical processes each time such illustration becomes possible and helpful.