A magnetite/oxidized carbon nanotube composite used as an adsorbent and a matrix of MALDI-TOF-MS for the determination of benzo[a]pyrene

A magnetite/oxidized carbon nanotube composite, Fe(3)O(4)@SiO(2)/OCNT, was fabricated in a simple way, and it was successfully used as a magnetic solid-phase extraction sorbent and a significant matrix of the matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) for the detection of benzo[a]pyrene (BaP).     

New dibenzocyclooctadiene lignans from the Kadsura ananosma

Fourteen new dibenzocyclooctadiene lignans, ananonins A-N (1-14), together with five known compounds, were isolated from the seeds of Kadsura ananosma. The structures and absolute configurations of 1-14 were established using a combination of MS, NMR, and CD techniques. The biological activity of these compounds was evaluated, and ananonin M (13) showed moderate neuroprotective effects in an in vitro assay.     

不同电性的纳米银对甲基橙光谱学性质的影响

通过吸收光谱和荧光光谱等手段研究了正/负电性纳米银对不同pH值的甲基橙(MO)溶液光谱学性质的影响.研究结果表明,正电性纳米银(P-Ag)与甲基橙作用形成新的复合物,吸收光谱表现为复合物体系的性质.负电性纳米银(N-Ag)与甲基橙静电排斥作用,相互作用较弱,吸收光谱仅表现为两者简单叠加.在正电性纳米银-甲基橙体系中,S1→S0荧光明显增强.当溶液pH=2.1时,荧光增强比率最大,当pH=4.8时,荧光增强比率最小;S2→S0荧光减弱,且与体系的pH值关系不大.在负电性纳米银-甲基橙体系中,仅少量纳米银存在条件下,S1→S0荧光略增强.在溶液pH=2.1时,荧光增强比率最大;S2→S0荧光明显减弱,且与体系的pH值关系不大.分析认为,不同电性的纳米银对甲基橙光谱学性质影响不同,与纳米银与甲基橙分子间相互作用、纳米银的局域场增强效应以及无辐射能量转移作用等密切相关.     

A μ9-iodide in a tricapped trigonal-prismatic geometry

Two luminescent, undecanuclear silver complexes [Ag(11)(μ(9)-I)(μ(3)-I)(3){E(2)P(O(i)Pr)(2)}(6)](PF(6)) [E = S (yellow), 1; Se (orange), 2], containing the first μ(9)-iodine inscribed at the center of a pentacapped trigonal-prismatic silver skeleton, were reported.     

异质双层磁性薄膜中自旋波的波形演化

在一维海森堡模型的基础上,采用界面参数化方法,将双层异质磁薄膜中自旋波本征值问题归结为联立求解能量约束方程和界面参数化方程.重点讨论体系中体模和完全禁闭模的波形演化过程,发现体系中体模波形随自旋波矢呈余弦变化,会出现局域共振现象.激发能对两子层中体模有较大的影响,不仅影响体模的振幅,而且还影响体模的波长.另外,激发能对体系中的完全禁闭模也有较大影响,随着激发能增大,铁磁层中完全禁闭模波长变短,波速变小,但振幅不变.     

Two-dimensional photoelectron momentum distribution of hydrogen in intense laser field

Two-dimensional (2D) electron momentum distributions and energy spectra of a hydrogen in an intense laser field are calculated by solving the time-dependent Schrödinger equation combined with the window-operator technique. Compared with the standard projection technique, the window-operator technique has the advantage that the continuum states of atoms can be avoided in the calculation. We show that the 2D electron momentum distributions and the energy spectra from those two techniques accord quite well with each other if an appropriate energy width is used in the window operator.     

Monomer Adsorption-Desorption Processes

We propose an adsorption-desorption model for a deposit growth system, in which the adsorption and desorption of particles coexist. By means of the generalized rate equation we investigate the cluster （island） size distribution in the dynamic equilibrium state. The results show that the evolution behaviour of the system depends crucially on the details of the rate kernels. The cluster size distribution can take the scale-free power-law form in some cases, while it grows exponentially with size in other cases.     

基于MILO结构的一种单边multipactor模型分析

根据高功率微波源相互作用腔的物理结构特性,以磁绝缘传输线振荡器（MILO）为例,建立了一种单边二次电子倍增效应（mulitpactor）模型.采用概率统计和蒙特卡罗（MC）模拟方法,计算了敏感曲线和二次电子的时间演化规律,分析了射频场参数对二次电子倍增效应的影响,并提出了减小和抑制二次电子倍增效应的具体措施. 关键词： 单边二次电子倍增效应 敏感曲线 二次电子的时间演化     

在Pt/CNTs催化层中预混-溶解La2O3颗粒来构筑孔结构促进甲醇电氧化

为认识孔隙度增加对甲醇电氧化的影响, 将熔盐法制备的La2O3颗粒与Pt/CNTs(碳纳米管)预混合然后用HClO4溶掉La2O3颗粒, 从而增加了Pt/CNTs催化层的孔隙度. 扫描电子显微镜(SEM)观察表明, 该处理可以形成孔结构. 用循环伏安和计时电流实验考察了孔隙度增加对甲醇电氧化的影响, 结果表明甲醇电氧化电流可增加57%. 分析认为, 电流增加的原因是由于多孔催化层中甲醇更易于到达Pt催化剂表面进行电氧化. 该研究表明, 通过在催化层中预混-溶解La2O3来增加孔隙是一种改善催化层性能的有效方法.     

黄海北部CDOM近紫外区吸收光谱特性研究

有色溶解性有机物(CDOM)近紫外区吸收光谱包含CDOM分子结构、组成等重要理化信息。利用2009年3月黄海北部海域CDOM吸收系数的实测数据,分析了该海域CDOM近紫外区的吸收光谱特性,结果表明:由于近岸陆源输入的影响,黄海北部海域CDOM构成差异较大,属于典型的二类水体;特定拟合波段范围的光谱斜率及特定波段处的吸收系数对CDOM分子量相对大小均具有一定的指示作用,250~275,350~400,300~350,275~300 nm波段的光谱斜率Sg,250~275,Sg,350~400,Sg,300~350,Sg,275~300与CDOM分子量相对大小指示参数M值的相关性依次递增,最高可达0.95,吸收系数ag(λ)与M值的相关性随波长增大逐渐变大,400 nm波段处相关性可达0.92;光谱斜率与吸收系数存在相关性与否由光谱斜率拟合波段范围及吸收系数获取波长共同决定,Sg,275~300与ag(400)的相关性最大,可达0.87。