THE CRYSTAL STRUCTURE OF BAYLEYITE

The bayleyite crystallizes in monoclinic space group C_2~5h-P2_1/c with a=6.499(1), b=15.235(5), c=26.513(6), β= 92.92(2)°, Z=4. Intensities of 3430 independent reflections are collected with diffractometer using MoKα radiation. The crystal structure has been solved by the Patterson method and refined by block least square refinement for positional parameters and isotropic temperature factor of non-hydrogen atoms. The final R factor is 0.038.The result of crystal structure analysis shows that the structure consists of discrete [UO_2(CO_3)_3]~(4-) ions and Mg~(2 ) cations are between slab-like units, but they are not in a slablike unit. Its crystal struture is different from that of liebigite which was determined by Appleman. Complexes and cations between slab-like units and in a slab-like unit are connected by hydrogen bonds formed by water molecules.     

VIRUS RESISTANCE OF TRANSGENIC TOBACCO PLANTS EXPRESSING TOBACCO MOSAIC VIRUS COAT PROTEIN GENE

An intermediate expressing vector carrying the tobacco mosaic virus (TMV, Chinese common strain) coat protein (CP) gene was constructed by recombinant DNA techniques. The TMV-CP gene was transferred into the tobacco genome via Ti plasmid and a large number of regenerated plants, including both systemic and local lesion hosts for TMV, were obtained. Southern blot analysis revealed that 1-5 copies of the CP gene were integrated into the tobacco genome. RNA and protein analysis demonstrated that the TMV-CP gene was correctly expressed in the transgenic plants. The abundance of TMV-CP mRNA in total leaf RNA accounted for 0.005-0.01%, while the amount of coat proteins reached 0.05-0.2% of the total leaf soluble proteins. Virus challenge experiments showed that the symptom development of virus infection was markedly delayed and the replication as well as the spread of the virus was significantly inhibited in the transgenic plants expressing the TMV-CP gene. Three of these plants were completely protected afte     

部分还原氧化石墨烯-Fe_3O_4对水中Mn(Ⅱ)的快速去除

采用改进的Hummers法制备了氧化石墨烯(GO),继而用一步共沉淀法制备了部分还原氧化石墨烯-四氧化三铁复合物(PRGO-Fe_3O_4).采用X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)、X射线能量色散光谱(EDX)、高分辨透射电子显微镜(HRTEM)、选区电子衍射(SAED)及傅里叶变换红外光谱(FTIR)等技术对其进行了分析表征;考察了p H值、接触时间、吸附材料用量、共存物质、GO的还原、循环使用次数等因素对Mn(Ⅱ)吸附行为的影响.结果表明,PRGO-Fe_3O_4中Fe_3O_4颗粒分布均匀,大小为15~20 nm,剩磁和矫顽力均很小.因Fe_3O_4颗粒的锚定作用,石墨烯片层很薄,使PRGO-Fe_3O_4对Mn(Ⅱ)表现出高效的吸附性能和良好的循环使用性能:当p H=7、PRGO-Fe_3O_4用量为500 mg/g时,对201.3211 mg/L的Mn(Ⅱ)溶液仅3 min即达吸附平衡,吸附率和吸附量分别为99.35%和404.49 mg/g,磁分离仅需10 s,经5次循环吸附后,容量保持率为首次的78%.机理与热力学研究结果表明,吸附为吸热、自发的单层化学吸附.     

遗传算法结合密度泛函理论研究Cu13团簇的几何结构

基于Gupta 多体势采用遗传算法详细计算了金属团簇Cu13的几何结构,对所得到的大量低能（基态及低激发态）结构,利用密度泛函理论方法作进一步优化计算。结果表明：尽管遗传算法所得基于Gupta原子间多体势的基态结构（Ih高对称性的紧致结构）并不对应第一性原理计算结果（非紧致低对称性基态）,但遗传算法给予的大量候选结构经密度泛函理论再次计算仍然可以高效地得到真实基态结构,体现出遗传算法在计算具有非紧致低对称性基态体系时的有效性。     

电力系统自动化设备的电磁兼容技术

当前随着电力自动化技术的迅猛发展,电力自动化技术的应用范围也不断扩大。在电力自动化技术应用过程中一个典型的问题日益突出,这就是电磁兼容问题。电磁兼容问题是一个重要问题,它影响着电力系统的正常运行。在人们对电力自动化技术的重视程度越来越高的背景下,加强电磁兼容技术的研究有着重要意义。     

Cu13团簇几何和电子结构的密度泛函研究

利用遗传算法结合Gupta原子间相互作用势,采用密度泛函理论,系统研究了带电 团簇的基态与低激发态的几何结构和电子结构并与中性Cu13团簇进行了对比．计算结果表明：对 Cu13（中性及带电）团簇,高对称性几何构型在众多异构中无能量竞争性优势,团簇基态结构皆为非紧致低对称性结构,对 负电Cu13找到一种新的低对称性最低能结构;带电明显影响团簇结构稳定性,带电Cu13团簇与中性Cu13团簇的结构稳定性序列显著不同;基态 Cu13（中性及带电）团簇的具有磁矩最小化效应,而其高对称性结构则有较大磁矩;计算所得Cu13团簇电离能及电子亲和势与实验结果相符．     

A New Method for Calculation of Single Seismic Phase of Cylindrically Multilayered Media Including Liquid Interlayer

A new method based on generalized reflection and transmission （R/T） coefficients method is proposed to calculate the single seismic phase （SSP） of cylindrically multilayered media including liquid interlayer. The use of normalization factors and normalized Lamé coefficients makes the algorithm stable numerically. Using the modified R/T matrices, we derive the iterative expressions of generalized R/T matrices, and by using the iterative relation we determine the SSP of each interface and the full waveforms. To show the superiority of this new approach for investigating of reflection and transmission properties of cylindrically multilayered media, we simulate the full waveforms and SSPs of cased hole model with annulus I （casing-cement interface） channelling （or, cross-flow）. The generalized reflection coefficient spectra and SSPs of interfaces obtained show the propagation mechanism of each component of full waveform clearly.     

光子扫描隧道显微镜光子隧穿可视化数值模拟

提出了一种新的入射波设置“三波法”,即将光子扫描隧道显微镜(PSTM)系统中的入射波、全内反射波和透射的隐失波同时设置为时域有限差分(FDTD)计算区域的入射源,克服了PSTM中应用FDTD所遇到的存在样品台(分层界面)和全内反射等困难。给出了PSTM中探针针尖与样品相互作用和光子隧穿的物理图像。模拟了PSTM探针等高扫描过程。给出了PSTM图像,比较了单光束照射与π对称照射等高度扫描曲线的不同,前者有一定的偏移,后者可纠正偏移。     

激光对运动圆柱体加热的几何学研究

 当激光无论从地面或是从空中辐照运动的圆柱体时,都涉及到入射激光相对于圆柱体的辐照方式。在一定假设下,导出了激光对抛射圆柱体表面加热时圆柱表面热加载功率密度分布公式,并结合一理想情况,针对光束入射角度因子、光斑中心的偏移、光斑形状的变化进行了解析计算分析。分析表明,即使圆柱体本身不做自转,圆柱体表面的光强分布中心也会发生偏移,分布也会发生变化,尤其沿圆柱体轴向的分布变化较大,必须结合实际加以细化研究。