Platinum nanoparticles from the hydrosilylation reaction: capping agents, physical characterizations, and electrochemical properties

Platinum nanoparticles synthesized by a unique synthetic approach, the hydrosilylation reaction, have been reported previously. However, the interaction between the underlying platinum nanosupport and the capping agents is poorly understood. Here we continue to investigate Pt nanoparticles from the hydrosilylation reaction to address this issue and present the characterization results of nuclear magnetic resonance, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. These characterization results conclude that two different modes of binding of the aliphatic capping agents with the platinum surface are attributed to the formation of Pt-C bonds under excess olefin concentration and Pt-Si bonds under excess hydrosilane concentration. Morphology and UV-vis spectra of the platinum nanoparticles were explored by transmission electron microscopy, X-ray diffraction, and UV-vis spectroscopy. Moreover, electrochemical properties of the platinum nanoparticles were also studied by cyclic voltammetry and chronoamperometry.     

Four-wave mixing assisted stability enhancement: theory, experiment, and application

Stability enhancement on the basis of four-wave mixing (FWM) is proposed and proved for the first time to our knowledge. This technique is applied to dual-wavelength erbium-doped fiber lasers. Significant uniformity and stability of the novel fiber lasers are demonstrated experimentally.     

Forward scattering due to slow-down of the intermediate in the H + HD --> D + H(2) reaction

Quantum dynamical processes near the energy barrier that separates reactants from products influence the detailed mechanism by which elementary chemical reactions occur. In fact, these processes can change the product scattering behaviour from that expected from simple collision considerations, as seen in the two classical reactions F + H(2) --> HF + H and H + H(2) --> H(2) + H and their isotopic variants. In the case of the F + HD reaction, the role of a quantized trapped Feshbach resonance state had been directly determined, confirming previous conclusions that Feshbach resonances cause state-specific forward scattering of product molecules. Forward scattering has also been observed in the H + D(2) --> HD + D reaction and attributed to a time-delayed mechanism. But despite extensive experimental and theoretical investigations, the details of the mechanism remain unclear. Here we present crossed-beam scattering experiments and quantum calculations on the H + HD --> H(2) + D reaction. We find that the motion of the system along the reaction coordinate slows down as it approaches the top of the reaction barrier, thereby allowing vibrations perpendicular to the reaction coordinate and forward scattering. The reaction thus proceeds, as previously suggested, through a well-defined 'quantized bottleneck state' different from the trapped Feshbach resonance states observed before.     

波长重用-扩大基于单纤连接节点的WDM星形单跳网容量

针对可利用的有限信道波长数对基于单纤连接节点的WDM星形单跳网容量限制问题,本文提出了一种有效的解决方案-波长重用.根据该方案,在信道波长数一定的条件下,至少可使网络所支持的节点数-网络容量扩大一倍;在网络节点数不变时,则可大大减少网络节点的排队时延,缓和网络中各通信节点对数据信道波长使用权的竞争矛盾,使网络吞吐量增加1～3倍,有效地改善网络性能.本文首先论述了该基于单纤连接节点的波长重用WDM星形单跳网结构,接着分析了网络的波长重用特性,进而对所要求的光放大器增益和输出功率进行了计算;最后计算了网络的最大节点数和最大信道波长数.     

基于单纤连接节点的WDM星形网及其性能分析

研究基于单纤连接节点的WDM星形网及其性能。首先介绍了该WDM星形网物理结构、节点模块的逻辑结构。然后对网络的各主要性能参数进行了分析和计算,最后介绍了网络通信协议,即动态地址分配方案和传输控制协议。     

Research on particle dispersion in a plane mixing layer with coherent structures

The numerical simulation with two-way coupling was performed in a liquid -particle mixing layer and the corresponding experiment study was made. In the process of vortex rolling up and vortices pairing, the particles with different St number have a very different pattern of dispersion. The mean velocity of particle with St = 1 is higher than that of the fluid phase on the low-speed side, and lower than that of the fluid phase on the high-speed side. The RMS of particle approaches that of the fluid phase with decreasing particle St number. The RMS in the transverse direction is smaller than that in the streamwise direction. The velocity fluctuation correlation of particle is smaller than the Reynolds shear stress, the “overshoot“ phenomenon that the velocity fluctuation correlation of particle is larger than the Reynolds shear stress does not appear. The larger the St number of particle is, the wider the range of the particle dispersion will be. The computed results are in agreement with the experimental ones.     

结构稳定分析域外奇点法

利用等效横向荷载的概念，基于静力问题基本解，导出了平面杆系结构线性失稳分 析的域外奇点法. 该法避开使用形式复杂的稳定问题控制微分方程的基本解，使之 成为静力方法的一种直观推广，具有物理意义明确，便于实现等优点. 给出一数值算例，验证了方法的正确性与实用性.     

Identification and Quantification of Genetically Modified Moonshade Carnation Lines Using Conventional and TaqMan Real-Time Polymerase Chain Reaction Methods

Genetically modified carnation (Dianthus caryophyllus L.) Moonshade was approved for planting and commercialization in several countries from 2004. Developing methods for analyzing Moonshade is necessary for implementing genetically modified organism labeling regulations. In this study, the 5'-transgene integration sequence was isolated using thermal asymmetric interlaced (TAIL)-PCR. Based upon the 5'-transgene integration sequence, conventional and TaqMan real-time PCR assays were established. The relative limit of detection for the conventional PCR assay was 0.05 % for Moonshade using 100 ng total carnation genomic DNA, corresponding to approximately 79 copies of the carnation haploid genome, and the limits of detection and quantification of the TaqMan real-time PCR assay were estimated to be 51 and 254 copies of haploid carnation genomic DNA, respectively. These results are useful for identifying and quantifying Moonshade and its derivatives.