Van der Pauw Hall Measurement on Intended Doped ZnO Films for p-Type Conductivity

A Van der Pauw Hall measurement is performed on the intended doped ZnO films （Na doped ZnO） grown by using the molecular beam epitaxial method. All as-grown samples show n-type conductivity, whereas the annealed samples （annealing temperature 900℃） show ambiguous carrier conductivity type （n- and p-type） in the automatic Van der Pauw Hall measurement. A similar result has been observed in Li doped ZnO and in as-doped ZnO films by other groups before. However, by tracing the Hall voltage in the Van der Pauw Hall measurement, it is found that this alternative appearance of both n- and p-type conductivity is not intrinsic behavior of the intended doped ZnO films, but is due to the persistent photoconductivity effect in ZnO. The persistent photoconductivity effect would strongly affect the accurate determination of the carrier conductivity type of a highly resistive intended doped ZnO sample.     

Preliminary study of a niobium quarter-wave prototype cavity for a heavy-ion superconducting linac

Superconducting quarter-wave resonators,due to their compactness and their convenient shape for tuning and coupling,are very attractive for low-β beam acceleration.In this paper,two types of cavities with different geometry have been numerically simulated the first type with larger capacitive load in the beam line and the second type of lollipop-shape for 100 MHz,β=0.06 beams then the relative electromagnetic parameters and geometric sizes have been compared.It is found that the second type,whose structural design is optimized with the conical stem and shaping drift-tube,can support the better accelerating performance.At the end of the paper,some structural deformation effects on frequency shifts and appropriate solutions have been discussed.     

Directed Motion of a Molecular Motor Based on the Four-State Model with Unequal Substeps

A periodic one-dimensional four-state hopping model is proposed. In the model, the substeps betweenarbitrary adjacent states are unequal, and an explicit solution of the master equation is first obtained for the probabilitydistribution as a function of the time and position for any initial distribution with all the transients included. Next, thetransient behaviors in the initial period of time and the characteristic time to reach the steady state for the molecularmotor are discussed. Finally, we compare the steady state results to experiments and illustrate qualitatively the kineticbehaviors of a molecular motor under external load F.     

非Kolmogorov大气湍流温度谱标度指数的测量与分析

 阐述了非Kolmogorov湍流谱理论以及湍流谱标度指数的测量与计算方法。在近地面多个地点对大气湍流温度起伏进行了多次的实验观测,结果表明：实际大气湍流温度谱标度指数多数不等于-5/3,并且通常在-2到-1之间变化。分析了湍流温度谱标度指数与湍流发展程度的相关性,利用小波分析方法展现了不同湍流强度下湍流温度脉动能量在各尺度之间的分配状态,发现湍流温度谱标度指数的绝对值在一定程度上随湍流强度的增加而增大。     

毛细管电泳法评价细胞色素c与单链脱氧核糖核酸库的相互作用

以细胞色素c(Cyt c)为碱性蛋白质模型,建立了毛细管电泳评价Cyt c与3种不同链长的单链脱氧核糖核酸(ssDNA)库相互作用的评价方法,研究了离子强度对Cyt c与ssDNA库相互作用的影响。比较了Cyt c与含有20、40和60个随机碱基序列的3种不同链长的ssDNA库的作用及基于未涂层毛细管和涂层毛细管的毛细管区带电泳方法。因碱性蛋白质在未涂层毛细管管壁上存在吸附,因此利用未涂层毛细管区带电泳不能区别3种ssDNA库与其作用的差异。利用涂层毛细管电泳法,在压力辅助的反向电压下,根据游离ssDNA库的峰面积变化可比较3种ssDNA库与细胞色素c的相互作用差异。结果表明,含有20个随机寡核苷酸链长的ssDNA库与Cty c的作用最强。此外,NaCl浓度显著影响Cyt c与ssDNA60库的作用。在优化的实验条件下,0.02 mol/L NaCl有利于两者的相互作用。调节盐浓度可抑制非特异性静电作用,能提高碱性蛋白质适配体的单轮筛选效率。利用未涂层毛细管电泳分析复合物及游离ssDNA库的峰面积变化,可优化有利复合物形成的盐浓度。     

TiO2／Al2O3负载量对气相酯交换合成碳酸甲丙酯的影响

采用XRD、N2 physical adsorption、XPS、NH3-TPD和吡啶吸附IR等技术,对碳酸二甲酯和丙醇气固相合成碳酸甲丙酯的TiO2/Al2O3催化剂进行了表征.实验结果表明,TiO2/Al2O3表面的Lewis酸中心是反应的催化活性位,酸性主要来源于Al2O3,TiO2起修饰作用,有利于选择性生成碳酸甲丙酯.随着Ti负载量的增加,TiO2在Al2O3表面由高度分散状态向晶态转变,其比表面积逐渐降低,但是TiO2/Al2O3的表面酸性质没有受到显著影响,L酸量先是增加,而后略有下降.当Ti负载量为5%时,DMC的转化率及MPC的选择性分别达到54.3%和88.1%.     

新的双枝[1,3,4]-噁二唑衍生物的设计与微波合成

在微波辐射条件下,以三氯氧磷作环合剂,以双酰肼为中间体,快速有效地合成了一系列新的1,3-二[(5-芳基-1,3,4-噁二唑-2-基)甲氧基]苯类化合物.十二个目标化合物(5a-5l)和五个中间体(4c,4d,4e,4j,4k)均为未见文献报道的新化合物,其结构经核磁、红外、质谱和元素分析所确证.该方法的显著优点是简单...     

水热法合成纳米氧化铜及其对盐酸异丙嗪的电化学传感研究

采用简单的水热法一步反应,制备了尺径均一的纳米氧化铜颗粒并构建了纳米氧化铜修饰电极。结果表明,该修饰电极对盐酸异丙嗪的电化学氧化有显著的电催化作用,研究了各种因素包括pH值、修饰剂用量、扫速以及共存离子等对电极响应的影响,优化了各项测试条件。该方法测定盐酸异丙嗪的线性范围为0.5~150μmol/L,检出限为1.3×10-7 mol/L,同时成功测定了药物中盐酸异丙嗪的含量。     

STUDY OF OPTICAL PUMPING OF ALKALI ATOMIC BEAM IN STRONG MAGNETIC FIELDS

We have gained a very comprehensive set of results for infrared diffraction (10.6μm wavelength) from fabricated single grooves of reflection with widths in the range of 5μm to 65μm. The experimental results show that the diffraction can still occur when the groove width becomes comparable to or less than the wavelength of the probing light. Variations of the diffraction intensities have a very regular sinusoidal relationship with the polarization angle of the incident light; and the diffraction intensities are the when the incident light is TM polarized. However, the diffraction intensities will be a minimum when the incident light is TE polarized; and the biger the diffraction angle, the higher the rate of change of the diffractive intensity with increasing polarization angle of the incident light.     

左截断数据中的Fisher信息量

本文研究左截断数据(U,V)含θ的Fisher信息量,并给出了基于分布和失效率表示的两个表达式.特别在Koziol-Green模型下研究左截断观测数据(U,V)含θ的Fisher信息量与完全数据X含θ的Fisher信息量的关系,得出在该模型下左截断观测数据(U,V)含θ的Fisher信息量不仅未损失,反而增加的结论.