泥沙输移的理论研探

本文通过对泥沙颗粒在水中的受力情况分析，从理论上导出了描述推移质运动的数学表达式．在此基础上，又导得了挟沙水流的底部含沙量，从而使泥沙运动的扩散方程能够方便地运用到工程实际问题之中．     

基于惯性释放理论及子模型法的平衡轴支架优化

为提升平衡轴支架强度计算准确度及全面性,建立了某6x4自卸载货车刚柔耦合的整车模型,计算了各工况下车架连接点的载荷,并以此作为边界载荷输入,在利用惯性释放原理提升边界设置合理性的基础上,运用子模型法克服了惯性释放无法进行接触非线性计算的问题,通过建立接触单元、细化网格等方法,对该支架进行了七工况的结构非线性强度计算,并...     

浅谈桥梁深基坑挡土墙防护施工方案

本文根据该项工程实际情况和相关技术标准、水文地质特征,对施工准备、测量放线、基坑开挖、挡土墙施工、基坑监测等关键部分进行深入研究。     

高放废液玻璃固化工艺冷试验装置的设计和验证试验

设计、安装了一套玻璃固化冷试验装置,作了多轮工艺冷试验,取得了一定的经验。本文介绍了装置的设计参数和工艺冷试验对设备的考验结果。     

果汁非酶褐变的机制及控制措施

本文阐述了果汁非酶褐变的机制：焦糖化反应、美拉德反应、抗坏血酸氧化分解和多元酚氧化缩合,并对目前常用的抑制果汁非酶褐变的方法进行了综述.     

Sorption and displacement of pyrene in soils and sediments

Sorption isotherms of pyrene on soils and sediments were examined to understand its sorption behavior. All systems examined exhibited nonlinear sorption. Sorption nonlinearity was found to be a function of the polarity index of soil/sediment organic matter (SOM), suggesting that the degree of condensation of SOM, characterized by its polarity index, was correlated with the sorption behavior of pyrene. The polarity index of SOM could be a new factor for explaining the sorption nonlinearity. The sorption affinity of two soils and two sediments for pyrene increased with decreasing SOM polarity. A higher sorption affinity in the two soils was associated with a higher degree of condensation of SOM compared to that of the two sediments. A displacement test was performed after pyrene sorption using phenanthrene as a displacer. Pyrene was displaced in all systems examined, and nonlinearity became less pronounced after displacement. Such an increase in isotherm linearity implied that sorption site energies became more homogeneous after displacement. Furthermore, the site energy distribution IE*) derived from the Freundlich model parameters showed that energy reduction of high-energy sites was more significant than that of low-energy sites after displacement. In addition, a decrease in sorption capacity after displacement could be ascribed to the partial depletion of sorption sites by the displacer. The displacement data indicated that the cocontaminant can have potential effects on the fate and bioavailability of anthropogenic organic pollutants sorbed in soils and sediments, thus affecting their exposure risks.     

Root uptake and phytotoxicity of ZnO nanoparticles

Increasing application of nanotechnology highlights the need to clarify nanotoxicity. However, few researches have focused on phytotoxicity of nanomaterials; it is unknown whether plants can uptake and transport nanoparticles. This study was to examine cell internalization and upward translocation of ZnO nanoparticles by Lolium perenne (ryegrass). The dissolution of ZnO nanoparticles and its contribution to the toxicity on ryegrass were also investigated. Zn2+ ions were used to compare and verify the root uptake and phytotoxicity of ZnO nanoparticles in a hydroponic culture system. The root uptake and phytotoxicity were visualized by light scanning electron, and transmission electron microscopies. In the presence of ZnO nanoparticles, ryegrass biomass significantly reduced, root tips shrank, and root epidermal and cortical cells highly vacuolated or collapsed. Zn2+ ion concentrations in bulk nutrient solutions with ZnO nanoparticles were lower than the toxicity threshold of Zn2+ to the ryegrass; shoot Zn contents under ZnO nanoparticle treatments were much lower than that under Zn2+ treatments. Therefore, the phytotoxicity of ZnO nanoparticles was not directly from their limited dissolution in the bulk nutrient solution or rhizosphere. ZnO nanoparticles greatly adhered on to the rootsurface. Individual ZnO nanoparticles were observed present in apoplast and protoplast of the root endodermis and stele. However, translocation factors of Zn from root to shoot remained very low under ZnO nanoparticle treatments, and were much lower than that under Zn2+ treatments, implying that little (if any) ZnO nanoparticles could translocate up in the ryegrass in this study.     

形变量和冷却速度对SCM435冷镦钢形变诱导铁素体相变的影响

通过热模拟试验研究了两相区轧制,研究了形变量(15％～40％)和冷却速度0.8℃/s和1.2℃/s对SCM435冷镦钢的形变诱导铁素体相变的影响.结果表明:SCM435钢在奥氏体和铁素体两相区(750～850℃)轧制,在0.8℃/s的冷速下,随形变量增加,形变诱导铁素体体积分数呈升高趋势,并存在粒状珠光体组织,硬度呈先...     

Quick qualitative analysis of PCDD/Fs from the iron ore sintering process

Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry(GC×GC-TOFMS)was applied to the quick qualitative analysis of 17 types of polychlorinated dibenzo-p-dioxins and furans(PCDD/Fs)from the iron ore sintering process.The GC×GC-TOFMS parameters were evaluated and optimized to yield a complete separation for the 17 types of PCCD/Fs from interference and to the attainment of high sensitivity.After optimization,all the 17 types of PCCD/Fs were separated within 42.5 min.Th...     

大学化学课程混合式教学模式的实践

大学化学课程教学是非化学化工专业人才培养的重要环节,课程教学的不断完善是提升高等教育质量的关键。大学化学课程教学实践证明,采用混合式教学模式能够融合信息化教育与传统教育的优势,真正践行以学生为中心的现代教育理念,有助于培养学生能力和提高教学质量。