烘箱消解—分光光度法测定地表水中有机磷

以烘箱代替压力蒸汽消毒器进行消解,采用过硫酸钾氧化—钼酸铵分光光度法测定地表水中的有机磷.实验结果表明,该法可简化消解过程,使温度易于控制,提高了有机磷测定方法的稳定性,同时该方法易于操作,其准确度、精密度、检出限等均令人满意.     

碳化硼微粉的低温合成

以聚乙烯醇和硼酸为原料,首先合成聚乙烯醇硼酸酯前驱物凝胶,然后将前驱物热解及碳热还原制备碳化硼粉末。考察了聚乙烯醇与硼酸的物质的量比,前驱物热解温度,碳热还原温度以及还原时间等因素对碳化硼合成的影响。采用IR、化学分析、XRD、离心粒度分析、SEM等方法对中间物及产物进行了表征,确定了中间物及产物的组成、物相、粒度分布及形貌。研究结果表明：前驱物合成的适宜原料配比是n(聚乙烯醇)∶n(硼酸)=4∶1;前驱物在600 ℃下热解2 h,在1 300 ℃下碳热还原2 h,得到粒径为10 μm左右的碳化硼微粉。     

两种负载膜对纳米Fe~(3+)/TiO_2光催化活性的影响

用溶胶-凝胶法制得的纳米Fe3+/TiO2分别以玻璃和琼脂糖为负载体,采用浸渍-提拉法制备Fe3+/TiO2玻璃负载膜,水热合成法制得Fe3+/TiO2琼脂糖凝胶负载膜,通过降解某制药厂的制药废水,探讨两种负载膜对纳米Fe3+/TiO2光催化活性的影响及用琼脂糖为载体的可行性。结果表明,两种负载膜中纳米Fe3+/TiO2的晶相不变,但琼脂糖凝胶负载膜中纳米Fe3+/TiO2粒子的团聚较少,且不易脱落,重复使用性能高,光催化活性明显较Fe3+/TiO2玻璃负载膜强,从而显示了琼脂糖为载体的可行性、优越性和实用性。     

原料粒度对煤矸石烧结砖结构和性能的影响

将煤矸石粉碎至三种不同的粒度,经过陈腐、压制成型、干燥、烧成后制得煤矸石烧结砖。利用X射线衍射仪、扫描电子显微镜研究烧结砖的物相组成和显微结构,并对其抗压强度和吸水率等性能进行了研究。结果显示,煤矸石原料的粒度和烧结保温时间对烧结砖的吸水率和抗压强度有较大影响。利用粒度小于0.15mm的煤矸石原料制备的烧结砖综合性能较好,1100℃烧结3h时,吸水率为17.63%,抗压强度达到22.47MPa,符合普通烧结砖的有关国家标准要求。     

氧化焰CuO-MnO_2-NiO-TiO_2系金属光泽釉制备及快烧工艺研究

以铅熔块为基础釉、CuO-MnO_2-TiO_2-NiO金属氧化物为析晶剂,制备低温金属光泽釉。通过考察釉料配方、添加物的含量、烧成制度等工艺因素对金属光泽釉的影响做了研究。实验结果表明:最优配方为Mn/Cu质量比为4、TiO_2 20%、NiO 3.5%。     

高碾压混凝土坝施工过程仿真研究

本文根据碾压混凝土坝施工特点，采用计算机系统仿真技术和排队随机仿真网络理论，建立了高碾压混凝土坝施工交通运输系统排队网络仿真模型和高碾压坝施工浇筑过程仿真模型。应用该模型可以较好地研究高碾压混凝土坝施工过程中混凝土的运输和大坝浇筑过程问题，通过算例分析，可以看出：采用这种模型进行计算机仿真，所得结果可为高碾压混凝土坝施工组织设计提供一定参考。     

Degradation of C.I. Acid Orange 7 by heterogeneous Fenton oxidation in combination with ultrasonic irradiation

BACKGROUND: A mesoporous alumina supported nanosized Fe₂O₃ was prepared through an original synthesis procedure and used as a heterogeneous catalyst for the Fenton process degradation of the model azo dye C.I. Acid Orange 7 enhanced by ultrasound irradiation (US/Fe₂O₃‐Al₂O₃‐meso/H₂O₂ system). The effect of various operating conditions was investigated, namely hydrogen peroxide concentration, initial pH, ultrasonic power and catalyst loading. RESULTS: The results indicated that the degradation of C.I. Acid Orange 7 followed a pseudo‐first‐order kinetic model. There exists an optimal hydrogen peroxide concentration, initial pH, ultrasonic power and catalyst loading for decolorization. The aggregate size of the spent catalyst was reduced after dispersion in water by ultrasonic irradiation. A very low level of iron leaching was observed ranging from < 0.1 to 0.23 mg L^?1. The intermediate products of C.I. Acid Orange 7 degradation were identified using gas chromatography–mass spectrometry (GC‐MS). CONCLUSION: The optimal conditions for efficient C.I. Acid Orange 7 degradation were pH close to 3, hydrogen peroxide concentration 4 mmol L^?1, catalyst loading 0.3 g L^?1, and ultrasonic power 80 W. Copyright © 2011 Society of Chemical Industry     

Preparation and orientation behavior of multi‐walled carbon nanotubes grafted with a side‐chain azobenzene liquid crystalline polymer

Covalent functionalization of multi‐walled carbon nanotubes (MWNTs) with side‐chain azobenzene liquid crystalline poly{6‐[4‐(4‐methoxyphenylazo)phenoxy]hexyl methacrylate} (PMMAZO) was successfully achieved via atom transfer radical polymerization. The resultant samples were characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis and transmission electron microscopy. The results of differential scanning calorimetry and polarized optical microscopy show that the liquid crystalline behavior of PMMAZO‐functionalized carbon nanotubes (CNT‐PMMAZO) is similar to that of the PMMAZO homopolymer. The orientation of MWNTs and CNT‐PMMAZO in a PMMAZO matrix in the presence of an electric field was investigated. The results indicate that the orientation of MWNTs is dominated by the viscosity of the matrix, but the orientation of CNT‐PMMAZO is controlled by both the viscosity and the presence of a liquid crystalline phase ascribed to the compatibility between MWNTs and PMMAZO becoming better after covalent modification. Copyright © 2010 Society of Chemical Industry     

Dependence of Dielectric Properties and Percolative Behavior on Phase Separation Structure Induced by Heterogeneous Carbon Nanofiber Distribution in Polymer Blend Nanocomposites

Many thermoplastics currently used in industry are in fact polymer blends and there is a pressing need to understand the dependence of the dielectric properties and percolative behaviors of the multi‐phase polymers with heterogeneous nanofiller distributions. When nanofillers distribution occurs in a polymer blend with phase separation, the dielectric properties and percolative behaviors have been shown to be more complex, and very sensitive to the distribution of the nanofillers. As a basis, the dielectric properties and alternating current (AC) conductivities of the binary carbon nanofiber (CNF)/high density polyethylene (HDPE) composite system were first characterized. Subsequently the properties of the ternary CNF/ultra‐high molecular weight polyethylene (UHMWPE)/HDPE composites were compared and analyzed. Combined with the evidence showing the phase separation of UHMWPE and HDPE and the CNFs exclusively dispersed in HDPE phase, it was inferred that UHMWPE acting as a non‐conductive additive, dramatically changed the uniform CNF presence in the matrix into a heterogeneous distribution. As a result, the dependencies of dielectric properties and conductivities on frequency were strongly affected, and in particular the percolative characteristics showed significantly increased dependencies.

     

用派克方程分析开关磁阻电动机

根据开关磁阻电动机气隙磁导的变化情况，把ＳＲＭ的一相绕组通电后的电磁关系，等效成一台假想的极对数Ｚ２／２，但运行于某种不对称的工作条件的三相凸极同步电动机的电磁关系，建立了与ＳＲＭ相等效的同步电动机模型，使用派克方程来分析ＳＲＭ的工作机理成为可能，并用坐标变换、Ｚ变换和拉氏变换法来求取ＳＲＭ的定子相绕组电流及电磁转矩。，