基于ANSYS Workbench的某汽车转向节的有限元分析

转向节是汽车中一个受力复杂且工况多变的重要零件,优化设计前必须进行强度分析.为了提供更加有效的强度分析依据,采用ANSYS Workbench建立了转向节的有限元模型,在分析转向节悬架、前车桥等其他零部件装配关系的基础上,建立了转向节结构约束载荷关系,按照汽车行驶中3种典型工况的名义载荷计算方法,利用有限元技术对转向节进行了结构静力学分析,得到了应力云图与变形图,并通过与传统的计算分析结果比较,得出有限元分析更准确的结论.     

旋转式尿素造粒喷头的设计理论研究及工程应用

采用极限负荷准则,在考虑造粒喷头极限造粒能力的情况下,避开了尿素造粒喷头内复杂的流体力学问题的计算工作,给出了常压式旋转式尿素造粒喷头的参数确定方法。针对典型的年产400 kt尿素装置造粒喷头的设计过程及使用情况进行了计算,比较了斜孔喷头和直孔喷头在造粒塔内的不同喷洒效果,分析了众多文献中报道的塔内驼峰产生的原因和改进方向。在理论计算的基础上,讨论了带压式喷头和常压式喷头的工作原理和影响因素及各自在实际生产中的优缺点。     

石墨烯量子点在生物传感和成像技术中的应用

石墨烯量子点具有许多吸引人的优点,如低细胞毒性、溶解能力强、稳定的光致发光、良好的生物相容性、高比表面积、电子高迁移率和可调节带隙等,因此,适用于构建传感系统和生物成像。根据近几年来,基于石墨烯量子点性质构建的光学生物传感器和电化学生物传感器以及石墨烯量子点在生物成像技术中的应用进行了综述。     

落实科学发展观,繁荣建筑创作

本文从落实科学发展入手,结合建筑设计行业及北京市建筑设计研究所近年来典型项目建筑创作的实践,论述了重申“建筑方针”的现实指导意义。     

Degradation of soil-sorbed trichloroethylene by stabilized zero valent iron nanoparticles: effects of sorption, surfactants, and natural organic matter

Zero valent iron (ZVI) nanoparticles have been studied extensively for degradation of chlorinated solvents in the aqueous phase, and have been tested for in-situ remediation of contaminated soil and groundwater. However, little is known about its effectiveness for degrading soil-sorbed contaminants. This work studied reductive dechlorination of trichloroethylene (TCE) sorbed in two model soils (a potting soil and Smith Farm soil) using carboxymethyl cellulose (CMC) stabilized Fe-Pd bimetallic nanoparticles. Effects of sorption, surfactants and dissolved organic matter (DOC) were determined through batch kinetic experiments. While the nanoparticles can effectively degrade soil-sorbed TCE, the TCE degradation rate was strongly limited by desorption kinetics, especially for the potting soil which has a higher organic matter content of 8.2%. Under otherwise identical conditions, ∼44% of TCE sorbed in the potting soil was degraded in 30 h, compared to ∼82% for Smith Farm soil (organic matter content = 0.7%). DOC from the potting soil was found to inhibit TCE degradation. The presence of the extracted SOM at 40 ppm and 350 ppm as TOC reduced the degradation rate by 34% and 67%, respectively. Four prototype surfactants were tested for their effects on TCE desorption and degradation rates, including two anionic surfactants known as SDS (sodium dodecyl sulfate) and SDBS (sodium dodecyl benzene sulfonate), a cationic surfactant hexadecyltrimethylammonium (HDTMA) bromide, and a non-ionic surfactant Tween 80. All four surfactants were observed to enhance TCE desorption at concentrations below or above the critical micelle concentration (cmc), with the anionic surfactant SDS being most effective. Based on the pseudo-first-order reaction rate law, the presence of 1×cmc SDS increased the reaction rate by a factor of 2.5 when the nanoparticles were used for degrading TCE in a water solution. SDS was effective for enhancing degradation of TCE sorbed in Smith Farm soil, the presence of SDS at sub-cmc increased TCE degraded by ∼10%. However, effect of SDS on degradation of TCE in the potting soil was more complex. The presence of SDS at sub-cmc decreased TCE degradation by 5%, but increased degradation by 5% when SDS dosage was raised to 5×cmc. The opposing effects were attributed to combined effects of SDS on TCE desorption and degradation, release of soil organic matter and nanoparticle aggregation. The findings strongly suggest that effect of soil sorption on the effectiveness of Fe-Pd nanoparticles must be taken into account in process design, and soil organic content plays an important role in the overall degradation rate and in the effectiveness of surfactant uses.     

医药级二硫代二苯并噻唑的合成

以乙醇水溶液为反应介质,采用环境友好型氧化剂H2O2,将2-巯基苯并噻唑(促进剂M)一步氧化制备高品质医药级二硫代二苯并噻唑(促进剂DM)。考察了反应温度、加料时间、反应时间、溶剂用量、物料配比等因素对反应结果的影响,得到的较佳工艺条件为反应温度35℃,加料时间3h,反应时间3h,V(溶剂)∶m(M)=3.5mL/g,n(M)∶n(H2O2)=2∶1.3。在上述条件下,DM的熔点可达182℃,纯度高达98%,产率高达98%。     

聚酰亚胺薄膜及纤维的探索研究

利用均苯四甲酸二酐(PMDA)、4,4'-二氨基二苯醚(4,4'-ODA)和自制三单体在强极性非质子有机溶剂N,N-二甲基乙酰胺(DMAc)中进行共缩聚反应,制得高粘度的聚酰胺酸(PAA)溶液,经涂膜、热亚胺化,得到坚韧透明的聚酰亚胺(PI)薄膜,其具有较好的拉伸断裂强度和合适的伸长率;同时将得到的PAA溶液进行湿法纺丝,制成PAA纤维,采用热亚胺化和高温拉伸的方法制得PI纤维,其断裂强度能达到3.67cN/dtex。     

Antifouling performance enhancement of polyethersulfone ultrafiltration membrane through increasing charge-loading capacity over Prussian blue nanoparticles

Prussian blue (PB), as a kind of regulator of charge-loading capacity, was first used to modify polyethersulfone (PES) membrane, and a novel PB/PES ultrafiltration membrane was prepared by non-solvent induced phase separation method. The physicochemical properties of PB-NPs and PB/PES membranes were analyzed by Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscope, atomic force microscope, and zeta potential analysis. It was observed that PB-NPs were uniformly distributed in the PES matrix and a lotus-seedpod structure was formed inside the membrane. The addition of PB-NPs improved the charge-loading capacity of the PES membrane. The permeation and antifouling performance were investigated by filtering bovine serum albumin aqueous solution with different pH values. The results showed that the PB/PES membrane with 0.2-wt% PB-NPs content had the excellent antifouling performance and the flux recovery ratio value reached 90.73%. Moreover, the long-term stability test showed that PB-NPs did not fall off after continuous pure water filtration, indicating that PB/PES membrane had a good stability.