Syntheses and crystal structures of triorganotin(IV) complexes based on mixed ligands of 2,4,5-trifluoro-3-methoxybenzoic acid and 4,4′-bipy

Four new complexes have been synthesized based on the 2,4,5-trifluoro-3-methoxybenzoic acid and 4,4′-bipy of the type [R₃Sn(OOCC₆HF₃OCH₃)]₂·(4,4′-bpy). All complexes were characterized by elemental, IR, ¹H, ¹³C and ¹¹⁹Sn NMR spectra analyses. Complexes 1 and 4 were also characterized by X-ray crystallography. Crystal structures of 1 and 4 show that the coordination number of tin atom is five and the 2D network is connected by intermolecular C–H···O interactions.     

直接甲醇燃料电池阴极催化剂的研究进展

直接甲醇燃料电池阴极催化剂的研究进展;直接甲醇燃料电池;阴极催化剂;氧还原;耐甲醇     

中温太阳能升级改造火电站的变辐照性能分析

我国中小火电站面临增容降耗的任务,利用中温太阳能改造火电站给水加热器投资少,改动小,技术难度低,具有一定应用市场.本文提出了一种对135 MW火电机组进行改造的典型方案,分析研究了辐照强度变化时系统变工况运行中重要参数的变化情况,并揭示了其变化原因,初步分析了变辐照条件下系统的经济性能,对我国火电站的改造具有一定参考价值.     

Synthesis and assembly of rare earth nanostructures directed by the principle of coordination chemistry in solution-based process

In this review, several typical nanomaterials are selected to demonstrate the coordination effect on the control of structure/microstructure/texture, surface/interface, particle size and morphology. Based on the principle of coordination chemistry, with some solution-based methods including solvothermal treatment and the thermolysis of metal complex precursors, a series of novel nanostructured rare earth compounds, such as ultra-small colloidal ceria nanoparticles, highly homogenous and stable ceria–zirconia solid solutions, and high-quality rare earth oxide and fluoride nanocrystals, etc., have been prepared by elaborately controlling the synthetic parameters and reaction kinetics. In order to reveal the mechanisms of synthesis, assembly, and properties, the phase, microstructure, texture, and surface state have been characterized systematically. The main applications of coordination chemistry principle in the synthesis and assembly of rare earth nanocrystals have been summarized, which also can be extended to direct the fabrication of other nanomaterials.     

A selective and ratiometric bifunctional fluorescent probe for Al3+ ion and proton

A new bifunctional probe based on a pyrene-amino acid conjugate for the differential response of Al(3+) and H(+) was demonstrated for the first time. Interestingly, two solvent-dependent sensing mechanisms for Al(3+), which feature a ratiometric change from excimer to monomer in CH(3)OH and a turn-on response in water, are also disclosed.     

Multiply twinned Pt-Pd nanoicosahedrons as highly active electrocatalysts for methanol oxidation

Bimetallic Pt-Pd nanoicosahedrons (NIs) with multiple {111} twins were obtained through a facile one-pot hydrothermal synthesis in a high shape selectivity of 82%. The {111}-enclosed NIs exhibited superior electrocatalytic activities to {111}-enclosed Pt-Pd nanotetrahedrons as well as commercial Pt catalysts (Pt black and Pt/C) for methanol oxidation.     

High-quality sodium rare-earth fluoride nanocrystals: controlled synthesis and optical properties

We report a general synthesis of high-quality cubic (alpha-phase) and hexagonal (beta-phase) NaREF4 (RE: Pr to Lu, Y) nanocrystals (nanopolyhedra, nanorods, nanoplates, and nanospheres) and NaYF(4):Yb,Er/Tm nanocrystals (nanopolyhedra and nanoplates) via the co-thermolysis of Na(CF3COO) and RE(CF3COO)3 in oleic acid/oleylamine/1-octadecene. By tuning the ratio of Na/RE, solvent composition, reaction temperature and time, we can manipulate phase, shape, and size of the nanocrystals. On the basis of its alpha --> beta phase transition behavior, along the rare-earth series, NaREF4 can be divided into three groups (I: Pr and Nd; II: Sm to Tb; III: Dy to Lu, Y). The whole controlled-synthesis mechanism can be explained from the point of view of free energy. Photoluminescent measurements indicate that the value of I610/I590 and the overall emission intensity of the NaEuF4 nanocrystals are highly correlative with the symmetries of the Eu3+ ions in both the lattice and the surface.     

Comparative analysis of the volatile components in cut tobacco from different locations with gas chromatography-mass spectrometry (GC-MS) and combined chemometric methods

A combined approach of subwindow factor analysis and orthogonal projection resolution was used to analyze the volatile components of cut tobacco samples from different sources. After extracted with simultaneous distillation and extraction method, the volatile components in cut tobacco from five different locations were detected by GC-MS. Then, the qualitative and quantitative analysis of the volatile components of cut tobacco from Changde area was completed with the help of subwindow factor analysis resolving two-dimensional original data into pure mass spectra and chromatograms. One hundred and two volatile components among 138 separated peaks were identified and quantified, accounting for about 88.90% of the total content. Finally, orthogonal projection method was used to extract the common peaks from different locations. Among the identified components, there were 74 components coexisting in five studied samples although the relative content of each component showed difference to some extent. The results showed a fair consistency in their GC-MS fingerprints. It was the first time to apply orthogonal projection method to compare different cut tobacco samples, and it reduced the burden of qualitative analysis as well as the subjectivity. The obtained results proved the combined approach powerful for the analysis of complex cut tobacco samples. The developed method can be used to compare the sameness and differences of cut tobacco from different sources and for quality control of cigarette production and materials.     

Self-organized monolayer of nanosized ceria colloids stabilized by poly(vinylpyrrolidone)

Four nanometer colloidal ceria nanocrystals in a fluorite cubic structure have been synthesized via an alcohothermal treatment at 180 degrees C for 24 h from Ce(NO(3))(3)*6H(2)O in ethanol, using various alkylamines including triethylamine, butylamine, and hexadecylamine as the bases and poly(vinylpyrrolidone) (PVP) as the stabilizer. They were characterized by multiple measurements of X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), ultraviolet visible (UV-vis) spectroscopy, dynamic light scattering (DLS), and infrared spectroscopy (IR). The introduction of PVP could effectively stabilize the cerium nuclei against self-aggregation and finally lead to the formation of the CeO(2) colloids. As compared with that of their precipitated counterparts, the UV-vis spectra showed a blue-shifted absorption edge for the as-obtained colloidal nanocrystals, revealing that their surfaces were well-passivated by PVP. Four types of self-organized monolayer patterns (i.e., isolated particles, short chainlike (pseudo-1-D aggregated), pearl necklace-like (1-D aggregated), and dendritic (pseudo-2-D aggregated) alignments) appeared for the as-obtained colloidal particles on the copper TEM grids, due to the delicate balance of the attractive and repulsive forces between the PVP-passivated CeO(2) nanocrystals during the irreversible evaporation of the solvent from various colloidal solutions under ambient conditions. The type of alkylamine and the concentration of PVP were confirmed to be the crucial factors determining the oriented-aggregation dimensionality of the CeO(2) colloids. Possible interparticle interaction modes have been suggested to explain such complex self-organization patterns exhibited by the as-obtained CeO(2) nanocrystals.     

以滤纸为模板合成新型介孔生物活性玻璃微管材料

用快速滤纸为生物模板,通过先浸渍后焙烧的方法合成了介孔生物活性玻璃微管材料。快速滤纸的管状结构被完美复制,其管壁为生成的介孔生物玻璃材料。通过在合成过程中引入铁元素可以使材料具有一定的磁性。材料的形貌、结构和磁性通过扫描电镜、粉末X射线衍射、透射电镜、氮气吸附-脱附曲线,红外光谱和磁滞回线进行了表征。并且通过模拟体液浸泡方法考察了其矿化能力,以地塞米松为模型药物考察其释药能力和生物相容性。合成的介孔生物活性玻璃微管材料具有复杂的管状多级结构、快速的矿化能力和良好的生物相容性,并具备一定的磁性,是一种不可多得的药物缓释材料。