Hydrothermal synthesis and crystal structures of two novel rare earth coordination polymers based on pyridine-2,6-dicarboxylic acid

Two novel rare earth coordination polymers, [La(pydc)₂(H₂O)][La(pydc)(H₂O)₂]·H₂O (1) and [Sm(pydc)₂(H₂O)][Sm(pydc)(H₂O)₂]·H₂O (2) (pydc=pyridine-2,6-dicarboxylate) were hydrothermally synthesized and characterized by the elemental analyses, IR spectra and TG analyses. Single crystal X-ray diffractions show that 1 and 2 are isostructural compounds. In the compounds of 1 and 2, the 1D lanthanide helical chains are connected each other by lanthanide binuclear dimer as building blocks to form a novel 3D covalent framework.     

Notes on the Paper “On SS-Quasinormal and S-Quasinormally Embedded Subgroups of Finite Groups” of Shen et al.

Mathematical Notes - We correct an error in the paper of Z. Shen, S. Li, and J. Zhang published in [4]. In addition, we give an answer to a question posed by the authors.     

质谱在多金属氧簇化学中的应用

随着多金属氧簇化学的发展,迫切需要将多金属氧簇的液相反应过程和固相结构有机结合起来,以便更好地指导功能导向性多金属氧簇的设计与合成。传统的分析方法对一些特殊结构的多金属氧簇以及溶液自组装机理的研究具有局限性。随着软电离技术的发展,尤其是电喷雾电离(ESI)和基质辅助激光解吸电离(MALDI)的发明,质谱(MS)技术越来越多应用在简单无机化合物、配合物及金属有机化合物的研究中。多金属氧簇属无机高分子,是一类结构较特殊的无机配合物,多阴离子自身常带多个负电荷。钼、钨等具有较多同位素,可方便通过理论模拟与实际测量同位素分布的对比确定簇离子的准确组成。本文综述了质谱技术在多金属氧簇化学中的应用,如ESI-MS分析多阴离子在溶液中存在形式、监测反应过程、推断自组装机理,并对其在多金属氧簇化学中的应用前景进行了展望。     

Dual stacked partial least squares for analysis of near-infrared spectra

A new ensemble learning algorithm is presented for quantitative analysis of near-infrared spectra. The algorithm contains two steps of stacked regression and Partial Least Squares (PLS), termed Dual Stacked Partial Least Squares (DSPLS) algorithm. First, several sub-models were generated from the whole calibration set. The inner-stack step was implemented on sub-intervals of the spectrum. Then the outer-stack step was used to combine these sub-models. Several combination rules of the outer-stack step were analyzed for the proposed DSPLS algorithm. In addition, a novel selective weighting rule was also involved to select a subset of all available sub-models. Experiments on two public near-infrared datasets demonstrate that the proposed DSPLS with selective weighting rule provided superior prediction performance and outperformed the conventional PLS algorithm. Compared with the single model, the new ensemble model can provide more robust prediction result and can be considered an alternative choice for quantitative analytical applications.     

Microporous Silica-supported Poi yoxometal ate Catalyst H3PW12O400/SiO2 with High Activity for Acetal Reaction between Benzaldehyde and Ethylene Glycol

Keggin-type polyoxometalates (POMs) whose representative is H3PW12O40(PW12) exhibits a unique combination of physical and chemical properties. They have been widely used as acid catalysts in homogeneous and heterogeneous reaction systems. However, the catalytic activity of PW12 is so limited due to its very low specific surface area (≤9 m2/g)[1] that polar molecules can only react on its surface.     

温度敏感性PNIPAM-b-PZLL-b-mPEG三嵌段共聚物的合成与自组装研究

通过大分子引发剂引发ε-苄氧羰基-L-赖氨酸-N-羧酸酐(Lys-NCA)开环聚合和大分子缩合的方法合成了聚(N-异丙基丙烯酰胺)-b-聚(ε-苄氧羰基-L-赖氨酸)-b-聚乙二醇单甲醚三嵌段共聚物(PNIPAM-b-PZLL-b-mPEG).用GPC和1H-NMR对其结构进行了表征.用芘荧光探针法证明了该三嵌段聚合物形成胶束的性质并测定了临界胶束浓度(CMC).动态光散射(DLS)研究表明,在固定PNIPAM-b-PZLL链段长度的情况下,mPEG分子量为2000时,胶束在温度高于临界溶解温度(LCST)时发生聚集,mPEG分子量为5000时,胶束在LCST以上没有发生聚集.     

Measurement and modeling of density and viscosity of <Emphasis Type="Italic">n</Emphasis>-octanol–kerosene–phosphoric acid solutions in a temperature range 293.15–333.15 K

Densities and viscosities have been measured for the n-octanol + aviation kerosene (AK) + phosphoric acid (H₃PO₄) system with the mass fraction of H₃PO₄ in the range from w = 0 to 0.26 and in the temperature of 293.15–333.15 K. According to the experimental data, the measured viscosities were found well correlated with the temperature and mass fraction of H3PO4, which were fitted to regression equations. The result shows that the dilution effect of AK is obvious under the same temperature and mass fraction of H₃PO₄.     

Development and characterization of transparent waterborne polyurethane acrylate/fullerenols thin-film nanocomposite as thermal-insulating coating

Thermal-insulating coating can lower the energy consumption and cooling costs, which caters to the tendency of environmental protection and energy conservation. Transparent waterborne polyurethane acrylate thin-film nanocomposite was developed by incorporating the fullerenol C₆₀(OH)₁₂(ONa)₂ into the system using ultrasonic dispersion. The thin-film nanocomposite was then synthesized by ultraviolet radiation curing and chemical crosslinking, and its morphology and chemical structures were characterized. Thermogravimetric analysis and differential thermal gravity were used to evaluate the thermal stability. The surface and mechanical properties were tested by the pendulum hardness and MEK resistance. The optical and thermal-insulating properties were assessed by the ultravioletvisible-near infrared spectrophotometer and indoor environmental simulation experiment. The thermal-insulating measurements showed that the glass coated thin-film nanocomposite possessed better thermal-insulation effect than empty glass.