邻硝基苯基荧光酮-Tween 80双波长分光光度法测定微量铝

本文研究了在非离子表面活性剂Tween 80存在下Al(Ⅲ)与O-NPF显色反应的条件,在pH9.0～11.0的HBO_3-Na_2CO_3缓冲溶液中可形成稳定的紫色络合物,最大吸收波长为564nm,铝量在0～5μg/25ml范围符合比尔定律,采用双波长法摩尔吸光系数高达1.81×10~5。本法具有简便、快速、灵敏度高、准确性好等优点。     

Fast synthesis of dopamine-coated Fe3O4 nanoparticles through ligand-exchange method

A fast approach was described for the synthesis of water-dispersible monodisperse dopamine-coated Fe₃O₄ nanoparticles（DA-Fe₃O₄） with uniform size and shape via ligand-exchange of oleic acid on Fe₃O₄ using only 2 min.The prepared DA-Fe₃O₄ nanoparticles were characterized by transmission electron microscopy,Fourier transform infrared spectrometry,and vibrating sample magnetometer.The results indicated that the resulting DA-Fe₃O₄ nanoparticles had an average diameter of about 19.2 nm. The magnetic saturation value of the prepared DA-Fe₃O₄ nanoparticles was determined to be 72.87 emu/g,which indicating a well-established superparamagnetic property.     

钛钒铁间吸收增强效应研究及其校正

利用X射线荧光分析方法,采用电制冷Sic(PIN)探测器,对配制的Ti-V,Ti-Fe,V-Fe三种伪二元体系样品进行测量,得到了元素计数率归一系数(RK)与含最(WK)之间的关系曲线,对各组元素间的吸收-增强效应程度进行了定性分析.结果表明,Ti-V二元系中所表现的吸收增强效应较明显,Ti-Fe,V-Fe两种二元系中吸收增强现象不明显.同时,采用指数拟合的数学校正方法,对RK-WK关系曲线进行了拟合,从而获得元素X射线荧光计数率与含垦的函数方程.利用三组Ti-V二元系样品对此方法进行检验,与实际结果相比,对Ti,V元素的相对分析误差均在0.2%以内.     

热处理对MgB_2超导体超导电性和显微结构的影响

采用固相反应法常压下制备MgB2超导块材,研究两种不同的热处理工艺(淬火、预热)对MgB:超导电性和显微结构的影响.结果显示淬火有助于细化晶粒,提高样品的临界电流密度;预热在一定程度上提高MgB2样品的致密度和磁通钉扎力,其中随炉升温600℃预热1 h再升至750℃保温0.5 h后淬火的样品自场Jc达到0.586 MA/cm2,不可逆场超过7 T,20 K下在0.8T达到最大钉扎力Fpumax.     

高温超导量子干涉器件在磁性粒子标记免疫测定中的应用

具有超顺磁特性的Fe3O4纳米磁性粒子在外场中被极化时会产生沿极化方向的宏观磁矩,当撤销极化磁场后,利用高灵敏的高温超导量子干涉仪(SQUID)测量磁性粒子的磁弛豫行为.由于小尺度的磁性粒子磁性衰减很快,其行为遵循布朗弛豫;相较而言,通过生物待标记物连接的较大尺度磁性粒子或发生偶连的磁性团簇磁性衰减较慢,满足尼尔弛豫的条件.根据磁性颗粒的磁弛豫特性配合超导SQUID的低噪声实现对磁性粒子标记的微量生物待标记物的免疫检测.分别对平均尺寸为144nm的聚苯乙烯磁珠和406nm的二氧化硅磁珠的磁性衰减信号进行测量,得到了一些初步的实验结果.前者聚苯乙烯磁珠样品因磁珠尺寸太小,磁弛豫太快,未见明显的响应曲线;而后者的弛豫曲线遵循尼尔弛豫指数关系.结果表明粒子的有效弛豫依赖于磁性团簇的尺度.并且通过加大极化场,可以增强磁珠的尼尔弛豫信号,提高测量灵敏度。     

Synthesis of mesoporous carbon materials via enhanced hydrogen-bonding interaction

A general method based on two-phase polymerization has been described to synthesize mesoporous carbons via self-assembly. Mild reacting conditions and wide composition ranges are the obvious advantages of this method over the techniques previously reported.     

浅谈平面振子的阻尼运动

从动力学方程出发并结合Mathcad数值计算,研究了平面振子的阻尼运动,并分析了阻尼系数对平面振子运动轨迹的影响.     

Hybrid Composite of Polyaniline Containing Carbon Nanotube

Among various conducting polymers, polyaniline (PANI) is a unique and promising candidate for practical applications because it is not only highly stable in air and in some solvents, but also exhibits dramatic changes in its electronic structure and physical properties in protoactivate state1,2,3. The carbon nanotubes (CNTs) have been proven to possess exotic properties, such as high mechanical strength, flexibility and electric conductivity. The study of carbon-based nanostructures and ma…     

Continuous Production of Carbon Nanotubes by Using Moving Bed Reactor

Since the discovery in 19911, carbon nanotubes have been the subject of intensive research due to their extraordinary mechanical and electronic properties2-7. However, lack of sufficient amount of materials limited the study of the fundamental properties and development of more practical applications. It is highly desirable to have large quantities of pure nanotubes. To date, few methods have been developed for the production of high-quality tubes which can adapted to industrial production …     

回旋行波管动力学分析及数值计算

 以小回旋电子注、均匀截面光滑壁圆柱波导为例,对回旋行波管动力学色散方程作了解析分析和讨论;数值计算和分析了注波互作用耦合系数与电子注参数的相互关系,为优化选择电子注参数,提高注波互作用效率获得了依据。