Preparation and Characterization of Polymer‐Protected Pt@Pt/Au Core‐Shell Nanoparticles

Poly(N‐vinyl‐2‐pyrolidone) protected Pt‐core bimetallic Pt/Au‐shell (Pt@Pt/Au) nanoparticles were prepared by multi‐step reduction of HAuCl₄ and H₂PtCl₆ alternately by hydrogen adsorbed on platinum atom. Transmission electronic microscopy (TEM) and x‐ray diffraction (XRD) were used to characterize Pt@Pt/Au nanoparticles. The structure of the shell of the nanoparticles seems to be the Au‐Pt solid solution.     

Rheological Properties of Mixed Aqueous Solutions of Geminis (12‐3‐12,2Br−) and SDS

The rheological properties of surfactant solutions are the main parameter that affects the surfactant application. In this work, the rheology of the mixed system 12‐3‐12,2Br^?/SDS/H₂O was discussed particularly. The relationship between the microstructure of surfactant aggregates and rheology of mixed solutions was explored. It is shown that the rheological properties of solutions have different behaviors at different molar ratio of two surfactants under given total concentration. With the increase of molar ratio (12‐3‐12,2Br^?/SDS), the solution change from Newtonian liquid into positive thixotropy then to negative thixotropy, at last turn to positive thixotropy again, and ATPS becomes the dividing line. The difference of rheological properties is the embodiment of difference for surfactant aggregates' microstructures. The cryo‐TEM results shown that the solutions containing aggregates with big size, such as rodlike micelles, multilamellar micelles, show positive thixotropy. However, the solutions containing lamellar micelles or liquid crystal will show negative thixotropy. The positive thixotropy endows the mixied system a potential application in enhanced oil recovery.     

Studies on the Effects of Additional Components on Micellization of CTAB via Surface Tension Measurements

The effects of Tris-HCl buffer solution on the cmc of cetyltrimethylammonium bromide (CTAB) were studied by surface tension measurement. The result shows that the effect of the buffer solution depends on the interaction between CTAB and NaCl and the structure accelerants of water, Tris. A series of parameters, including the critical micelle concentration (cmc), the surface tension at cmc (γ_cmc), the adsorption efficiency (pC₂₀), and the effectiveness of surface tension reduction (∏_cmc) were obtained from the surface tension measurements in the presence of glycine with different concentration in the Tris-HCl buffer solution at 27°C. In addition, maximum surface excess concentration (Γ _max) and minimum surface area per molecule (A_min) at the air-water interface were estimated according to the Gibbs adsorption isotherm. The thermodynamic parameters (Δ C _p,m , Δ H _m,tr , Δ C _p,m,tr ) of micellization for CTAB in the absence and presence of glycine at different temperature were also been obtained.     

溶胶-凝胶新方法合成介孔铁酸铜纳米粉体催化剂上CO低温氧化(英文)

Mesoporous CuFe2O4 solid solution nanopowders with high specific surface areas were synthesized by a novel, very simple and inexpensive sol-gel route using propylene oxide as gelation agent, and used as the catalyst in low temperature CO oxidation. The samples were characterized by X-ray diffraction, N2 adsorption-desorption, thermogravimetric/differential thermal analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and temperature-programmed reduction. The results revealed that the samples have a nanocrystalline structure with crystals in the range of 10 to 25 nm, and that all the catalysts have mesoporous pores. The addition of Cu into iron oxide affected its structural and catalytic properties. The sample containing 15 mol% Cu showed the highest specific surface area and catalytic activity, and showed high catalytic stability in low temperature CO oxidation.     

Preparation and Characterization of Al8.31Si1.91Mg3.78O20/Al4.8Si1.2O9.6/Mg2.0Al4.02Si4.98O18 Multiphase Material

A two-step sintering method was used to prepare Al8.31Si1.91Mg3.78O20 (corundum solid solution)/Al4.8Si1.2O9.6 (mullite solid solution)/Mg2.0Al4.02Si4.98O18 (cordierite solid solution) multiphase material, for the purposes of making these three crystal structures have point defects which could help the particles diffuse and transfer at high temperature, accelerate the sintering efficiently and enhance the material strength as well as the bulk density. The impacts of different formulas on the structure and properties of the multiphase material were investigated. With XRD and SEM analyses, for each sample, the crystal structure and microstructure were characterized, the crystalline phase content and cell parameters were determined with Rietveld Quantification software, and the properties were tested. The comparative optimal formula determined was calcinated chamotte of 80wt% and calcinated sludge of 20wt%; and its corresponding bending strength and retention rate of bending strength after a thermal shock were 29.74 MPa and 80.15%, respectively.     

AgGa(S1-xSex)2固溶体的电子结构和光学性质

采用基于赝势平面波基组的密度泛函理论方法, 对一系列具有黄铜矿结构的AgGa(S_1-xSe_x)₂固溶体的构型、电子结构、线性和二阶非线性光学性质进行了系统研究. 结果表明, 各固溶体具有类似的能带结构, 体系带隙随x值增加而逐渐减小. 当所引入的Hartree-Fock交换项贡献为22.56%时, 对应的杂化PBE泛函得到的带隙值与实验结果相近. 固溶体的各种光学性质, 包括折射率、双折射率、反射率、吸收系数和二阶倍频系数等均随着组成的改变呈现出有规律的变化趋势, 变化范围介于AgGaS₂和AgGaSe₂二者之间. 因此, 利用固溶体光学性质的变化规律, 可从中寻找出具有特定光学性能的晶体材料.     

Ni-La/CexZr1-xO2对甲烷部分氧化/CH4-CO2重整耦合制合成气的催化剂制备及反应性能

通过共沉淀法制备铈锆固溶体作为载体,采用等体积、分步浸渍的方法制备了一系列10% Ni-3% La/CexZr1-xO2（X=0、0.16、0.5、0.75、1）催化剂,并将其应用到甲烷部分氧化和甲烷二氧化碳重整耦合制合成气的反应中。对不同Ce/Zr比的催化剂性能展开研究,采用XRD、H2-TPR、SEM手段对载体及催化剂进行了表征。结果表明,铈锆固溶体的形成不仅提高了催化剂表面活性组分的分散度,使催化剂表面NiO晶粒尺寸从26.5 nm减到13.7 nm;而且能够加强活性组分与载体之间的相互作用,提高催化剂的热稳定性能;随着Ce/Zr比的增加,催化剂的转化率、选择性及稳定性随之增强,其关系为：Ni-La/Ce0.75Zr0.25O2 > Ni-La/Ce0.5Zr0.5O2 > Ni-La/Ce0.16Zr0.84O2。     

基于无线传感器网络的飞行器测控通信系统测量方案设计

随着航天技术的发展,飞行器测控通信系统需要测量的参数种类和数量不断增加,但同时要求系统在进行方案搭建时满足更高的可靠性、更小的体积和更小的设备质量。为解决这类问题,提出了基于无线传感器网络的飞行器测量方案,方案重点从节点配置、时间同步、网络拓扑、能源供应等方面对方案进行阐述,最后给出了应解决的关键技术攻关方向。     

A uniqueness theorem of radially symmetric positive stationary solutions for a competition–diffusion system

In this paper, as a first step to study the global structure of solution, we treat a class of reaction–diffusion systems with competitive interaction, and discuss a uniqueness theorem of radially symmetric solutions for the system. To do this, the comparison principle and the shooting method are employed, and the spatial profile is investigated.     

两大部类持续扩大再生产的优化

基于经典的马克思两大部类社会再生产公式,建立了离散确定型的持续扩大再生产的优化问题的动态规划模型.在生产资料部类的不变资本产出率高于另一部类的条件下,动态规划的指标函数是作为决策变量的生产资料部类积累率的单调函数,因而可以使用逆序解法或者顺序解法,获得唯一的最优策略和最优指标函数.借助《资本论》中的一个举例,计算验证了最优解.