Catalyst-Controlled Selectivity in Oxidation of Olefins: Highly Facile Success to Functionalized Aldehydes and Ketones

Catalysis Letters - The attractive challenge in green chemistry is exploring novel heterogeneous catalyst system for catalyst-controlled product selectivity for oxidation of olefins. Hence, we...     

Production of glass-ceramics using Municipal solid waste incineration fly ash

Municipal solid waste incineration(MSWI) fly ash is a by-product from municipal waste incineration.According to incomplete statistics, each year more than one million tons MSWI fly ash was produced in China. Owing to high heavy elements content, widely used disposal methods of landfill are not suitable for MSWI fly ash treatment. In this study, by using MSWI fly ash as raw materials, glassceramics was synthesized for the solidification of heavy metals and waste recycle. Process parameters, including composition, heat treatment temperature and time, were studied and optimized. Under optimizing conditions, the product has good properties of density of 3.42 g·cm~(-3) and Vickers hardness of 6.91 GPa. Moreover, the leaching concentration of heavy metal elements meets allowable values of toxicity characteristic leaching procedure(TCLP).This study offers an alternative for MSWI fly ash recycle.     

Photovoltaic Study of Photoelectrochemical Biofuel Cells Sensitized by Porphyrin Derivatives with Different Substituents

Two porphyrin derivatives with different substituents were investigated as dyes for the titanium dioxide (TiO₂) film electrode to construct new two-compartment photoelectrochemical biofuel cells (PEBFCs). The two porphyrin derivatives were tetrakis(4-carboxyphenyl)porphyrin (TCPP) and meso-tetra(p-hydroxyphenyl)porphine (THPP). To determine how cell performance was affected by the dye with different substituents, we analyzed the photochemical and photoelectrochemical properties of the two dyes by physical characterization and photoelectrochemical experiments. The UV–Vis absorption spectra and X-ray photoelectron spectra indicated that the interactions between the dye and TiO₂ decreased in the order of TCPP > THPP, which was also in accord with the results of Fourier transform infrared. In addition, TCPP and THPP were calculated using the density functional theory and the time-dependent density functional theory, and the calculation result exhibited that the radiative lifetime decreased in the order of TCPP > THPP. Compared with THPP, TCPP with longer excited-state was expected to enhance the performance of a PEBFC. We measured and compared the incident photon-to-collected electron conversion efficiency and the light-to-electrical conversion efficiency (η) of the porphyrin-sensitized photoelectrochemical biofuel cell. The photovoltaic characteristics showed the TCPP was more effective compared to the THPP, which obviously showed that the experimental results were consistent with theoretical expectation. These results revealed that the kind of the substituent for the porphyrin influenced the photovoltaic properties of the PEBFC.     

Exposure to Diflubenzuron Results in an Up-Regulation of a Chitin Synthase 1 Gene in Citrus Red Mite,Panonychus citri (Acari: Tetranychidae)

Chitin synthase synthesizes chitin, which is critical for the arthropod exoskeleton. In this study, we cloned the cDNA sequences of a chitin synthase 1 gene, PcCHS1, in the citrus red mite, Panonychus citri (McGregor), which is one of the most economically important pests of citrus worldwide. The full-length cDNA of PcCHS1 contains an open reading frame of 4605 bp of nucleotides, which encodes a protein of 1535 amino acid residues with a predicted molecular mass of 175.0 kDa. A phylogenetic analysis showed that PcCHS1 was most closely related to CHS1 from Tetranychus urticae. During P. citri development, PcCHS1 was constantly expressed in all stages but highly expressed in the egg stage (114.8-fold higher than in the adult). When larvae were exposed to diflubenzuron (DFB) for 6 h, the mite had a significantly high mortality rate, and the mRNA expression levels of PcCHS1 were significantly enhanced. These results indicate a promising use of DFB to control P. citri, by possibly acting as an inhibitor in chitin synthesis as indicated by the up-regulation of PcCHS1 after exposure to DFB.     

膨润土对Pb~(2+)的吸附及铝的影响研究

研究膨润土对水溶液中铅的吸附特性以及铝对铅吸附的影响。通过各组吸附实验,建立膨润土对水溶液中铅离子的吸附最佳条件,天然膨润土对铅的吸附平衡时间约为60 min,其吸附符合一级动力学方程;铅吸附最适p H=9;天然膨润土对水溶液中铅离子的吸附规律符合Freundlich等温方程和Langmuir等温方程,呈显著相关性;加入少量铝离子时,吸附除铅能力增强,但继续增加铝浓度,去除能力降低,该现象主要通过铝盐水解所致的p H变化起调节作用,电中和作用不明显。     

呼和浩特回族聚居区的保护与更新发展

本文以呼和浩特回族聚居区为切入点,分析其特色与保护价值。针对目前城市发展过程中存在的一系列问题,提出统一协调建筑特色、完善人性化设施、大力发展民族特色产业等观点。     

HIPS/PPO共混物拉伸和冲击断裂面的电镜观察

研究了高冲击强度聚苯乙烯(HIPS)/聚苯醚(PPO)共混物断面3个特征区的形貌特征及形成机制,分析了它们对材料力学性能的影响。     

压缩垃圾车结构的载荷描述与优化设计

通过建立垃圾堆曲面函数,给出自重、惯性、压缩、挤入和推出等基本工况下压缩垃圾载荷作用机理的变参数数学描述以及各种实际组合工况下压缩垃圾载荷的数学表达式.利用ANSYS软件对压缩垃圾车进行结构有限元分析,调校载荷数学表达中的可变参数,保证分析计算与试验测试结果一致,采用导重法对压缩垃圾车结构的外形与构件尺寸进行优化设计,在结构最大应力从504 MPa下降到176 MPa的同时,结构质量减少29.3 %.     

锻造成形有限元数值模拟技术

数值模拟是目前塑性成形分析最有效的方法.通过有限元数值模拟,可以预测金属流动规律,获得应力场、应变场及温度场等场量分布及变化,进而揭示出复杂的变形机理.介绍锻造成形有限元法以及模拟中的关键技术,并以基于DEFORM软件的热-力耦合模拟实验为例,探讨了数值模拟技术在工程实际中的指导意义.