Influence of AC Electric Field on Macroscopic Network of Carbon Nanotubes in Polystyrene

CVD‐grown multiwall carbon nanotubes are dispersed in styrene monomer. During the polymerization of styrene, an AC electric field is applied to induce the CNTs to align along the electric field line to form a macroscopic nanotube network in polystyrene matrix. The dielectrophoresis force and the electric field redistribution at the CNTs apexes are responsible for alignment of the CNTs as well as bonding between the CNTs. Parameters such as field strength and nanotube weight fraction are varied. The results indicate that the macroscopic CNTs alignment along electric field direction can be observed only if the AC voltage reaches or is higher than certain values, and the higher the electric field frequency is, the more uniformly the CNTs align along electric field direction. In addition, nanotube concentration also affects the alignment of CNTs. According to the results of this study, the CNTs will align into a developed network in polystyrene matrix under a proper combination of three parameters of the electric field voltage, frequency, and the CNTs concentration.     

Microfluidic chip electrophoresis for biochemical analysis

Microfluidic chip electrophoresis has been widely employed for separation of various biochemical species owing to its advantages of low sample consumption, low cost, fast analysis, high throughput, and integration capability. In this article, we reviewed the development of four different modes of microfluidics‐based electrophoresis technologies including capillary electrophoresis, gel electrophoresis, dielectrophoresis, and field (electric) flow fractionation. Coupling detection schemes on microfluidic electrophoresis platform were also reviewed such as optical, electrochemical, and mass spectrometry method. We further discussed the innovative applications of microfluidic electrophoresis for biomacromolecules (nucleic acids and proteins), biochemical small molecules (amino acids, metabolites, ions, etc.), and bioparticles (cells and pathogens) analysis. The future direction of microfluidic chip electrophoresis was predicted.     

利用光泵磁共振曲线测量氢原子密度

本文给出利用光泵磁共振曲线测量氢原子密度的实验.在我们的实验中,当射频源放电功率一定时,在25~61℃的泡温范围内测量到9.2×10¹¹~1.6×10¹¹(原子/厘米³)的氢原子密度.实验结果表明,当放电功率一定时,氢原子密度随泡温升高而下降.     

部分线性变系数模型的Profile Lagrange乘子检验

对于部分线性变系数模型附有约束条件时的估计与检验问题,基于Profile最小二乘方法给出了参数部分以及非参数部分的约束估计并研究了它们的渐近性质,并针对约束条件构造了Profile Lagrange乘子检验统计量,证明了该统计量在原假设下的渐近分布为χ2分布,从而将Lagrange乘子检验方法推广到了半参数模型上.     

NMR Study of Laser-polarized 129Xe in Low Pressure Natural Xenon Gas

The NMR signal from the laser-polarized t29 Xe in low-pressure natural xenon gas has been observed with a Bruker WP-80SY NMR spectrometer. The laser-polarized 129 Xe was produced by the method of laser pumping and spin exchange in a magnetic field of 1.87 Tesla. It is obtained experimentally that the nuclear spin relaxation rate 1/T1 of laser-polarized 129Xe are (4.03±1.97)×10-3/see～(2.21±0.78)×10-3/see in the range of the 3.33×103 Pa～8.29×104 Pa Xe gas pressures, the apparent wall relaxation rate 1/Tw* =(1.98±0.18)×10-3/see, and the relaxation rate coefficient C of 133Cs-129Xe spin exchange is (2.81±0.74)×10-16 em3/sec.     

Apportionment of wind from water erosion on the hillslopes of China Northern Loess Hilly Area,by the fallout 137Cs technique

Journal of Radioanalytical and Nuclear Chemistry - Differences in the net soil loss and apportionment of wind from water erosion on hillslopes were analyzed and evaluated quantitatively through...     

利用NMR谱仪及模拟机实现量子算法

报道了利用NMR谱仪和NMR模拟机实现量子算法.以天然苯为样品,我们分别用500 M谱仪和NMR模拟机实现了量子D-J算法,Grover搜寻算法及受控非门(C NOT).通过比较实验谱和模拟谱发现二者能很好符合.利用NMR模拟机实现量子算法比用NMR谱仪更为方便、清晰.     

离子色谱法检测食品添加剂焦碳酸二甲酯中的氯离子

建立离子色谱法检测食品添加剂焦碳酸二甲酯（DMDC）中的杂质氯离子的方法。样品用水溶解超声定容后,采用SH-AC-1阴离子交换柱（250mm×4．6mm,5μm）分离,抑制电导法检测。考察了淋洗液种类、浓度对氯离子与干扰离子分离度的影响。最佳色谱条件：以0．005mol／L的四硼酸钠水溶液为淋洗液,流速1．0mL／min。在此条件下,样品中的氯离子可以和其它干扰离子分离,而且分离度达3．0以上,峰形对称。在氯离子浓度为0．1～5．0mg／L的范围内,可获得良好的线性关系,线性相关系数大于0．999;氯离子检出限（S／N=3）达0．007mg／L,加标回收率为97．5％～98．9％。该方法可以用于食品添加剂DMDC中氯离子的测定。     

New role of antibody in bacterial isolation

To eliminate the interference caused by Pseudomonas aeruginosa in the isolation of Salmonella, a rabbit polyclonal antibody against P. aeruginosa was prepared by inoculating four New Zealand rabbits with the pathogen. The antiserum was purified using saturated ammonium sulfate and added into Rappaport-Vassiliadis medium with soya (RVS) broth and Muller-Kauffmann tetrathionate novobiocin broth (MKTTn broth) to evaluate whether it could inhibit the growth of P. aeruginosa. Observations by scanning electron microscopy demonstrated that P. aeruginosa was attacked and destroyed by the antibody when incubated for 10 min at 37 degrees C. The activity of the antibody was also effective against 11 other strains of P. aeruginosa. Twenty-six strains of Salmonella were mixed with P. aeruginosa in RVS and MKTTn broth at 37 degrees C for 12 h, respectively, and the cultures were plated on Salmonella chromogenic medium (SCM; Oxoid, Basingstoke, UK). Only Salmonella grew on SCM; five colonies were randomly selected for identification by VITEK 2 (bioMérieux, Lyon, France). Additionally, when mixed with two strains of Enterobacter cloacae (ATCC 700323 and YG001), the prepared antibody did not affect the growth of E. cloacae. The results demonstrated that the microbicidal activity of the antibody did not affect the tested Salmonella sp. or E. cloacae strains. Therefore, the antibody generated could be used to increase the accuracy of Salmonella isolation.     

主动约束层阻尼振动控制研究进展

主动约束层阻尼(Active Constrained Layer Damping, ACLD)是以可控的压电材料代替被动约束层中不可控的约束层,通过可控的约束层主动地控制黏弹性材料的剪切变形以进一步增大其对振动能量耗散的主动阻尼形式,它充分结合了主动控制与被动阻尼作用各自的优势,使得其在结构振动控制方面显示出极好的应用价值.本文首先解释了ACLD的基本结构和阻尼机理,然后综述了最近几年有关ACLD在结构建模,控制方案及结构优化等方面的最新研究进展,最后指出了应用前景并总结了进一步研究的问题.