镍催化氟代烯基硼酯与烷基卤化物Suzuki偶联反应

有机化合物特定位点嵌入氟原子或含氟片段,可以产生独特的生物或物理性质改变.单氟取代烯基是生物医药领域理想的酰胺键替代物,在医药化学、药物研发等方向已经获得广泛的应用.通过溴化镍（Ⅱ）二乙二醇二甲醚复合物、4,4'-二叔丁基-2,2'-二吡啶的催化体系,实现了多种氟代烯基硼酯与一级烷基卤化物碘代物、溴代物以及二级烷基溴代物的Suzuki偶联反应.该反应具有良好的收率和优秀的官能团兼容性,能够兼容酯基、氰基、醇羟基等多种具有有机合成化学价值的官能团,为单氟取代烯烃的合成提供了方法.机理实验表明该反应可能经历烷基卤化物自由基均裂历程.     

Field measurements of bottom boundary layer processes and sediment resuspension in the Changjiang Estuary

A field observation of the hydrodynamics and the sediment resuspension in a bottom boundary layer was carried out in the Changjiang Estuary, during July-August 1997. Using bottom field research facilities, detailed measurements of near-bottom currents and suspended sediment concentration distribution within 1.0 m above bed have been obtained in the Changjiang Estuary——a high concentration estuary. An Acoustic Suspended Sediment Monitor (ASSM) wasused to observe near bed sediment resuspension processes. In addition, the log-profile method was applied to estimating hydraulic roughness Z0 and bottom shear stress values (or friction velocities u). Further understanding of sediment suspension mechanics and hydrodynamic characteristics will require the long-term measurements of near bed processes.     

云南松松塔中两种新木脂素圆二色谱的密度泛函研究

采用梯度校正的密度泛函理论方法,计算了云南松松塔中分离的2种新木脂素的绝对结构为7S,8R的手性结构、电子吸收光谱、电子圆二色谱、红外振动光谱和振动圆二色谱,计算值与实验值相符. 分子轨道和振动模式分析,两种新木质素具有相似的手性光谱. 电荷密度转移对电子圆二色谱具有主要贡献;而振动圆二色谱主要源于分子骨架运动.     

H2,C2H4在铂及铂锡合金上化学吸附的量子化学计算

本文详尽地分析了推广的休克尔分子轨道理论方法(EHMO)中参量化过程。借助于计算双原子体系选择出合理的经验参数和近似方式,引进了过渡金属内层原子轨道排斥作用项。分别计算了H,H₂,C₂H₄和C₂H₃在铂及铂锡合金上化学吸附键能,计算结果表明,同铂金属比较,在铂锡合金上H原子,C₂H₄分子的化学吸附键变弱在锡富集的铂锡合金上单个的铂原子不能解离吸附H₂分子,在铂锡合金上C₂H₄脱氢反应较难进行。     

山楂中硒的测定

用荧光法测定了山楂中硒的含量，结果表明，山楂中含有痕量硒。     

CO在Ni/Ti2O3体系上吸附的DV-Xα研究

用DV-X_α方法计算了Ni_3Ti_2O_3,CO-Ni_3Ti_2O_3,CO-Ni_4和CO-Ni_3Ti各原子簇的电子结构。这些原子簇分别模拟担载在Ti_2O_3上的金属Ni,CO在Ti_2O_3担载的Ni表面的化学吸附,CO在纯Ni及Ni_3Ti表面上的化学吸附。比较计算的结果表明,Ti~(3+)离子和金属Ni之间形成强共价键;成键过程中电子由Ni向Ti~(3+)转移,Ni原子带0.07个正电子电荷。计算的Ni-CO键和C—O键的Mulliken重叠集居指出,Ti~(3+)-Ni之间的强成键及电子转移没有导致Ni吸附CO的活性降低及吸附的CO的活化程度的提高。这就表明,电子因素,即Ti~(3+)-Ni之间的强成键及电子转移似乎不是导致所谓的金属载体强相互作用(SMSI)的主要原因。     

Charge noise acting on graphene double quantum dots in circuit quantum electrodynamics architecture

We investigate the dephasing mechanisms induced by the charge noise and microwave heating effect acting on a graphene double quantum dot(DQD) capacitively coupled to a microwave resonator. The charge noise is obtained from DC transport current, and its contribution to dephasing is simultaneously determined by the amplitude response of the microwave resonator. A lowfrequency 1/f-type noise is demonstrated to be the dominant factor of the dephasing of graphene DQD. Furthermore, when the applied microwave power is larger than-90 d Bm, the dephasing rate of graphene DQD increases rapidly with the increase of microwave power, and fluctuates slightly with the applied microwave power smaller than-90 d Bm. Our results can be applied to suppress the impeditive influence on the dephasing of graphene-based devices associated with microwave input in the perspective investigations.     

随机稀释基底上刻蚀模型动力学标度行为的数值模拟研究

表面界面动力学粗化过程是凝聚态物理领域重要的研究内容,为研究基底不完整性对刻蚀模型动力学 标度行为的影响,本文采用Kinetic Monte Carlo(KMC)方法,分析研究了在随机稀释基底上刻蚀模型(Etching model)生长表面的动力学标度行为.研究发现:尽管随机稀释基底的不完整性会对刻蚀表面的动力学 行为产生显著的影响,导致刻蚀表面粗糙度指数和生长指数有明显的增加, 但其仍基本满足原有的动力学标度规律.此外,本文还对刻蚀表面动力学标度指数的有限尺寸效应进行了 分析讨论.     

高钒高速钢冲击磨损性能与机理的研究

以高铬铸铁Cr26为对比材料,利用可模拟破碎机耐磨件实际服役工况(主轴转速2 840 r/min)的WM-1型冲击磨损试验机,以初始直径约25 mm的鹅卵石颗粒为磨料研究了高钒高速钢V9的冲击磨损性能及其磨损机理.结果表明:高钒高速钢V9的耐磨性为高铬铸铁Cr26的3倍以上;在颗粒的高速冲击下,高铬铸铁的磨损机理主要为划伤和碳化物碎裂导致剥落;高钒高速钢的磨损机理主要为在鹅卵石颗粒冲击下,基体受到显微切削而导致碳化物脱落,使基体受到颗粒的蚕食作用而不断反复进行的磨损过程.