动脉中非平稳流动壁面剪切力及其Hilbert-Huang变换

本文通过数值方法求解均匀动脉中的非平稳脉动流,给出了通过测量非平稳脉动血流量确定壁面切应力的方法.作为算例,采用实测的大鼠颈总动脉流量信号,求出了均匀动脉壁面切应力波形.进一步对求得的切应力波形进行经验模态分解(EMD),得到了切应力波形的各内在模态(IMF),以及Hilbert幅值谱.从切应力波形经Hilbert-Huang变换得到的IMF和Hilbert谱图可以明显地看出切应力各频率成分的物理意义.所得结果为进一步深入研究非平稳脉动切应力与血管重建的关系提供了一种方法学基础.     

Suzuki Reaction of Aryl Bromides Using a Phosphine-Free Magnetic Nanoparticle-Supported Palladium Catalyst

A palladium catalyst immobilized on superparaganetic nanoparticles was prepared with a palladium loading of 0.30 mmol/g. The catalyst was characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, thermogravimetric analysis, Fourier transform infrared, atomic absorption spectrophotometry, and nitrogen adsorption. The immobilized palladium catalyst was an efficient catalyst without added phosphine ligands for the Suzuki cross-coupling reaction of several aryl bromides with phenylboronic acid. The recovery of catalyst was simply by magnetic decantation in the presence of a magnet. The immobilized palladium catalyst can be reused many times without significant degradation in catalytic activity. No leaching of active palladium species into the reaction solution was detected.     

三元TBZ/HPB-铜(Ⅱ)-L-蛋氨酸配合物的合成、表征、抑菌活性及与DNA的作用

本文合成了2个新的三元铜(Ⅱ)配合物:[Cu(TBZ)(L-Met)(H2O)]ClO4.H2O(1)和[Cu(HPB)(L-Met)]ClO4(2)[TBZ=2-(4′-噻唑基)苯并咪唑,HPB=2-(2-吡啶)苯并咪唑,L-Met=L-蛋氨酸]。通过元素分析、摩尔电导率、IR、UV-Vis及电喷雾质谱对这些配合物进行了表征。用二倍稀释法研究了配合物的抗菌活性,发现配合物对金黄色葡萄球菌(Staphylococcus aureus,G+),枯草杆菌(Bacillussubtilis,G+),沙门氏杆菌(Salmonella,G-)和大肠杆菌(Escherichia coil,G-)具有良好的抑制作用。采用电子吸收光谱、荧光光谱、粘度测定及琼脂凝胶电泳方法研究了配合物与DNA的相互作用,结果表明,配合物以插入方式与DNA作用,在维生素C存在下通过羟自由基.OH,单线态氧1O2或者1O2类似物如Cu-O2,切割pBR322 DNA双螺旋结构。     

互补对偶结构的三值ECL锁存器设计

在分析发射极耦合逻辑(ECL)电路的互补对偶特性基础上,指出了差分对的两个开关变量的不独立性及互补对偶特性,并设计了互补对偶结构的ECL三值D型锁存器.这种新型的D型锁存器电路比传统电路具有更简单的电路结构.它的输出是互补的双轨三值输出系统.应用这种新型锁存器设计的D触发器及时序电路将具有更简单的电路结构.     

Tm~(3+)掺杂Ge-Ga-Se玻璃中红外发光特性与多声子弛豫分析

用熔融急冷法制备了系列不同Tm3+掺杂浓度的Ge30Ga5Se65玻璃样品,测试了样品折射率、拉曼光谱、吸收光谱以及800nm激光泵浦下的近红外及中红外波段荧光光谱和荧光寿命。用Judd-Ofelt理论计算了Tm3+在Ge30Ga5Se65玻璃中的强度参数Ωi(i=2,4,6)、自发辐射跃迁概率A、荧光分支比β和辐射寿命τrad等光谱参数。讨论了800nm激光泵浦下掺杂1Wt%Tm3+样品在近红外1.23,1.48和1.8μm处的发光特性及各量子效率,研究了800nm激光泵浦下的样品中红外荧光特性与掺杂浓度之间的关系,计算了常温下该基质玻璃中Tm3+:3H5→3F4跃迁对于3.8μm处的多声子弛豫速率Wmp和Ge30Ga5Se65玻璃基质中多声子弛豫常数W(0)和电子-声子结合常数α值。结果表明Ge30Ga5Se65硒基玻璃较低的声子能量可以大大降低稀土离子能级间跃迁的多声子弛豫概率,从而提高中红外荧光发光效率,因此硒基玻璃作为稀土离子的掺杂基质材料对实现中红外荧光输出是非常有利的。     

On Problems in the Calculus of Variations in Increasingly Elongated Domains

This paper deals with minimization problems in the calculus of variations set in a sequence of domains, the size of which tends to infinity in certain directions and such that the data only depend on the coordinates in the directions that remain constant. The authors study the asymptotic behavior of minimizers in various situations and show that they converge in an appropriate sense toward minimizers of a related energy functional in the constant directions.     

CONSERVATION OF ENDANGERED ENDEMIC SEABIRDS WITHIN A MULTI‐PREDATOR CONTEXT: THE BARAU'S PETREL IN RÉUNION ISLAND

Abstract Seabirds breeding on islands are vulnerable to introduced predators, such as rats and cats, and the removal of such predators is generally viewed as a priority for seabird conservation and restoration. However, multiple invasive mammal species interacting may generate unexpected outcomes following the removal (eradication) of one species. Generally these indirect interactions are not well understood or demonstrated. We propose and study a prey (seabird)‐mesopredator (rat)‐superpredator (cat) model, taking into account the juvenile stages in the prey population, in order to direct conservation management for seabird conservation. We give a more biologically realistic differential system than those studied before (Courchamp et al. [1999] ; Fan et al. [2005] ), in particular for long‐lived seabird species. We present a theoretical study and show existence and uniqueness of a positive solution as well as a qualitative study of the equilibria that may appear. Because standard numerical methods, usually implemented in scientific softwares, can fail to give the right biological approximations ( Anguelov et al. [2009] ), we propose a reliable algorithm that preserves most of the qualitative properties of the continuous system, using the theory of nonstandard finite difference methods. Finally, we use biologically realistic parameters available for the representative Barau's petrel (Pinet et al. [2008] ), an endemic species from Réunion island, to present numerical simulations that support the theoretical study. Cats play the major role in seabird prey population dynamics. Seasonality in seabird breeding delays but does not prevent extinction. In all scenarios, cat control (or preferably eradication) is imperative to prevent extinction of vulnerable long‐lived seabirds, like the Barau's petrel.     

EESI-MS监测ZrOCl2·8H2O催化的Paal-Knorr反应

用电喷雾萃取电离质谱（EESI-MS）离线监测甲醇中,ZrOCl₂·8H₂O催化的苯胺和2,5-己二酮的Paal-Knorr反应,检测到中间体m/z 204和m/z 208,产物m/z 172和产物二聚体m/z 343的准分子离子信号,并对其进行了结构分析。     

Controlling Dual Molecular Pumps Electrochemically

Artificial molecular machines can be operated using either physical or chemical inputs. Light‐powered motors display clean and autonomous operations, whereas chemically driven machines generate waste products and are intermittent in their motions. Herein, we show that controlled changes in applied electrochemical potentials can drive the operation of artificial molecular pumps in a semi‐autonomous manner—that is, without the need for consecutive additions of chemical fuel(s). The electroanalytical approach described in this Communication promotes the assembly of cyclobis(paraquat‐p‐phenylene) rings along a positively charged oligomeric chain, providing easy access to the formation of multiple mechanical bonds by means of a controlled supply of electricity.     

诺氟沙星–铜(Ⅱ)-吡啶衍生物配合物的合成、表征及生物活性

诺氟沙星(NFA)(图1)(1-乙基-6-氟-1,4-二氢-4-氧代-7-(1-哌嗪基)-3-喹啉羧酸)是一种典型的喹诺酮类抗菌化合物,主要通过抑制DNA旋转酶和拓扑异构酶Ⅱ使脱氧核糖核酸、核糖核酸及蛋白质的合成受到干扰,使细胞不能再进行分裂,而起杀菌作用,具有广谱抗菌性[1].