季铵盐参与的直接化学选择性O-和N-烷基化反应

将羧酸或胺类化合物与季铵盐进行简单的混合加热,便可直接得到O-或N-烷基化产物。季铵盐中烷基的转移具有较好的选择性,其优先顺序为：苄基〉伯烷基〉仲烷基。     

软骨细胞黏弹性及恢复变形与年龄相关性研究

本文旨在表征年龄对软骨细胞在自然生长过程中的黏弹性和恢复变形能力的影响.结果表明:年龄对软骨细胞黏弹性及其恢复变形能力产生显著影响,老年组软骨细胞各项黏弹性参数值均明显高于幼年和中年组软骨细胞(p<0.000 1),而后两组无显著差异(p>0.05);老年组软骨细胞蠕变达到平衡态所需时间t_E显著小于幼年和中年组(p<0.05),而幼年和中年组无显著差异(p>0.05).老年组软骨细胞最大蠕变位移L_M显著大于幼年和中年组(p<0.005),而幼年和中年组无显著差异(p>0.05).老年组软骨细胞恢复变形时间t_R显著大于幼年和中年组(p<0.005),而幼年和中年组无显著差异(p>0.05).恢复变形前8s的分析发现,幼年组软骨细胞恢复变形率K_y显著高于中年和老年组(P<0.005),而中年组(K_α)和老年组(K_o)软骨细胞的恢复变形率无显著差异(p>0.05);此外,实验发现老年组软骨细胞的残余变形L_R比幼年和中年组显著增大(p<0.005),而后两组无显著差异(p>0.05).研究工作对于软骨组织工程、软骨细胞与支架材料相互作用以及探讨OA发生过程中的力学生物学机制具有理论意义.     

Sterilization of mycete attached on the unearthed silk fabrics by an atmospheric pressure plasma jet

The sterilization of the simulated unearthed silk fabrics using an atmospheric pressure plasma jet(APPJ) system employing Ar/O_2 or He/O_2 plasma to inactivate the mycete attached on the silk fabrics is reported. The effects of the APPJ characteristics(particularly the gas type and discharge power) on the fabric strength, physical-chemical structures,and sterilizing efficiency were investigated. Experimental results showed that the Ar/O_2 APPJ plasma can inactivate the mycete completely within 4.0 min under a discharge power of 50.0 W. Such an APPJ treatment had negligible impact on the mechanical strength of the fabric and the surface chemical characteristics. Moreover, the Ar ions, O and OH radicals were shown to play important roles on the sterilization of the mycete attached on the unearthed silk fabrics.     

直接进样-冷原子吸收分光光度法测定大气颗粒物中汞的含量

<正>大气中汞的来源主要有自然源和人为源,自然源包括土壤、水体、植被、森林火灾、火山爆发等,人为源包括化石燃料燃烧、金属冶炼、水泥制造等^[1-2]。据统计,全球每年向大气中排放汞的总量为5 000 t, 其中4 000 t来自人为排放。大气中的汞可以通过皮肤和呼吸进入人体,并且对神经系统造成危害^[3]。大气中的汞按照物理化学特性分类,一般可被分为气态元素汞、活性气态汞和颗粒态汞3种形态。     

强次指数分布族S*(γ)的μ积分尾分布的卷积等价性

在Klüppelberg提出强次指数分布族并研究其积分尾分布的次指数性的基础上,推广Foss等关于强次指数分布族S*的μ积分尾分布的次指数性结果,得到S*(γ)的μ积分尾分布的卷积等价性.     

Effect of pulsed bias on the properties of ZrN/TiZrN films deposited by a cathodic vacuum arc

ZrN/TiZrN multilayers are deposited by using the cathodic vacuum arc method with different substrate bias(from 0 to 800 V),using Ti and Zr plasma flows in residual N 2 atmosphere,combined with ion bombardment of sample surfaces.The effect of pulsed bias on the structure and properties of films is investigated.Microstructure of the coating is analyzed by X-ray diffraction(XRD),and scanning electron microscopy(SEM).In addition,nanohardness,Young’s modulus,and scratch tests are performed.The experimental results show that the films exhibit a nanoscale multilayer structure consisting of TiZrN and ZrN phases.Solid solutions are formed for component TiZrN films.The dominant preferred orientation of TiZrN films is(111) and(220).At a pulsed bias of 200 V,the nanohardness and the adhesion strength of the ZrN/TiZrN multilayer reach a maximum of 38 GPa,and 78 N,respectively.The ZrN/TiZrN multilayer demonstrates an enhanced nanohardness compared with binary TiN and ZrN films deposited under equivalent conditions.     

Lowering plasma frequency by enhancing the effective mass of electrons： A route to deep sub-wavelength metamaterials

Deep sub-wavelength metamaterials are the key to the further development of practical metamaterials with small volumes and broadband properties. We propose to reduce the electrical sizes of metamaterials down to more sub-wavelength scales by lowering the plasma frequencies of metallic wires. The theoretical model is firstly established by analyzing the plasma frequency of continuous thin wires. By introducing more inductance elements, the effective electron mass can be enhanced drastically, leading to significantly lowered plasma frequencies. Based on this theory, we demonstrate that both the electric and the magnetic plasma frequencies of metamaterials can be lowered significantly and thus the electrical sizes of metamaterials can be reduced to more sub-wavelength scales. This provides an efficient route to deep sub-wavelength metamaterials and will give rigorous impetus for the further development of practical metamaterials.     

熔融法制备金尾矿微晶玻璃及性能研究

以金尾矿为主要原料,采用熔融法制备CaO-Al2O3-SiO2系微晶玻璃.利用差热分析(DSC)、X射线衍射分析(XRD)、扫描电镜(SEM)等分析手段对所制备的微晶玻璃进行了分析测试与表征,并研究了不同晶化温度对制得微晶玻璃的物相组成、微观结构及性能的影响.结果表明:在850～ 950℃下,随着晶化温度的提高,所制备微晶玻璃的性能均提高.确定较佳的晶化制度为950℃保温3h,所制备微晶玻璃的热膨胀系数、抗折强度及密度分别为68.7×10-7/℃,122 MPa和2.836 g/cm3.     

基于差动电容传感器和89C51单片机的电子水平仪

针对原有的气泡式水平仪功能存在的不足进行了改进,改进后的仪器采用了变介质差动电容传感器,设计了电容传感器变换电路,将传感器电容的变化转换为信号频率的变化,用89C51单片机对信号进行处理和显示.实验结果表明,该方法制作的电子水平仪系统性能稳定,测量精度可达到0.01 mm/m.