Degradation of parathion methyl by reactive sorption on the cerium oxide surface: The effect of solvent on the degradation efficiency

A simple and easily scalable “wet” procedure was used to prepare nanocrystalline cerium oxide capable of destroying the toxic organophosphate pesticide parathion methyl. The synthetic procedure consists of the direct precipitation of cerous salt with aqueous ammonia in the absence of CO₂. The prepared cerium oxide was able to decompose the organophosphate compounds both in nonpolar (e.g., heptane) and polar aprotic (e.g., acetonitrile) solvents. However, in solvents with hydrogen-bond donating ability, the –OH groups on the cerium oxide surface were solvated and inactivated. The preferential solvation model was used to express the experimental dependencies of the cerium oxide degradation efficiency on the composition of the water-acetonitrile mixture. In certain solvent systems, some empirical polarity scales, such as the alpha-scale or the Dimrodth-Richardt parameter ET(30), may be correlated with the degradation efficiency of cerium oxide.     

吉林某弹药销毁场土壤炸药污染调查及其赋存状态研究

研究吉林某军事弹药销毁场土壤炸药污染程度以及炸药在土壤中的赋存状态,为炸药和重金属污染土壤修复提供针对性策略。采集了某弹药销毁厂焚烧销毁区表层土壤样品,分析了其理化性质和常见重金属元素含量,测试了土壤全样和不同颗粒度土壤样品中炸药污染物的含量,并结合热重-傅里叶变换红外光谱(TGA-FTIR) 对炸药污染土壤样品热力学行为的表征,探讨了炸药污染物的赋存状态,炸药和重金属组合污染特征等。土壤中含有高浓度的TNT、DNT、ADNT、RDX等炸药污染物及其降解产物,并表现出土壤细颗粒富集趋势,其中土壤全样中TNT总浓度达到了1.66×104 mg·kg-1,远远高于EPA推荐的土壤TNT指导限值,RDX超过了以土壤环境为目标的指导限值;销毁活动还造成了土壤中Pb、Cu、Zn重金属浓度的升高,分别为400 mg·kg-1,318 mg·kg-1,1030 mg·kg-1。土壤中受到重金属和有机质等因素的影响,土壤中经过长期老化的炸药污染物的热解行为明显不同于自由态的炸药分子,热解温度升高、过程延长。在销毁区炸药污染土壤的修复中,应加强炸药污染物与重金属相互作用的研究,并在修复治理实践中采取协同修复的策略。     

The cut‐tree of large trees with small heights

We destroy a finite tree of size n by cutting its edges one after the other and in uniform random order. Informally, the associated cut‐tree describes the genealogy of the connected components created by this destruction process. We provide a general criterion for the convergence of the rescaled cut‐tree in the Gromov‐Prohorov topology to an interval endowed with the Euclidean distance and a certain probability measure, when the underlying tree has branching points close to the root and height of order . In particular, we consider uniform random recursive trees, binary search trees, scale‐free random trees and a mixture of regular trees. This yields extensions of a result in Bertoin (Probab Stat 5 (2015), 478–488) for the cut‐tree of uniform random recursive trees and also allows us to generalize some results of Kuba and Panholzer (Online J Anal Combin (2014), 26) on the multiple isolation of vertices. The approach relies in the close relationship between the destruction process and Bernoulli bond percolation, which may be useful for studying the cut‐tree of other classes of trees. © 2017 Wiley Periodicals, Inc. Random Struct. Alg., 51, 404–427, 2017     

论地质灾害防治工程的地质观与工程观

概括前人的经验, 结合作者个人的实践, 本文较详细地讨论了地质灾害防治工程的地质观念与工程观念。提出地质观的核心问题是地质灾害体的变形破坏力学机理分析, 工程观观与工程观运用的最佳耦合。文中还讨论了超前预测的作用, 监测反馈与工程效果检验的关系, 以及地质工程师与设计工程师的关系等, 最后以链子崖危岩体防治工程为例进行了说明。     

Chemical aspects of the radiation stability of macrocyclic extractants designed for 90Sr separation

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黑龙江省矿区生态破坏与地质灾害及其防治

黑龙江省矿产分布情况和开发概况以及矿业开发在经济发展中占有重要地位 ;在矿业开发过程中引起的诸多生态破坏和地质灾害及其引起的危害 ,已引起高度重视 ;本文在综合论述黑龙江省矿区发展所带来各项利弊后提出了具体的防治对策。     

煤炭燃烧过程中N2O消除反应机理的密度泛函理论研究

用密度泛函理论B3LYP方法对煤炭燃烧过程中N₂O的消除反应进行研究。选用6-311++G**和aug-cc-pVTZ基组,优化了反应通道上反应物、过渡态和产物的几何构型。预测了它们的热力学性质(总能量、焓、熵和吉布斯自由能)及其随温度的变化。预测N₂O+CO反应的活化能为200 kJ·mol^-1,与实验值193±8 kJ·mol^-1较一致。计算了500~1 800 K 温度范围的反应速率常数。在N₂O的分解中,N₂O与H和CN自由基的反应为动力学优先进行的反应,其活化能为50~55 kJ·mol^-1。在B3LYP/aug-cc-pVTZ level水平下,N₂O+CN反应是热力学最有利的自发反应,其吉布斯自由能变化为-407 kJ·mol^-1。     

镁合金MB2在高应力三轴度下的拉伸破坏行为研究

通过光滑试件及不同曲率半径缺口圆柱试件的拉伸试验,实现对镁合金MB2的单向及多向应力状态加载。结合数值模拟分析,研究了不同试件在拉伸加载过程中应力状态的变化。以应力三轴度为参数,给出了镁合金MB2等效破坏应变的变化规律,在应力三轴度-等效破坏应变空间建立了镁合金MB2的失效破坏准则。利用扫描电镜对试件断口形貌进行观察,分析了导致材料宏观延性变化的微观损伤机理,对不同应力状态下镁合金MB2的失效破坏行为做出了合理解释。     

内爆炸下钢管混凝土结构变形与破坏的试验分析及数值模拟

钢管混凝土结构由于具有良好的力学性能和低经济成本而受到广泛应用,因此对它的研究很多,但对它在爆炸作用下尤其是内爆炸作用下的研究很少,故分析钢管混凝土结构在内爆炸下的变形与破坏具有重要意义.本文通过试验与数值模拟方法,分析了内爆炸下钢管混凝土结构在具有二条预制狭缝时的变形与破坏情形.结果表明,钢管变形主要发生在靠近狭缝处,变形大小随药量的增加而增大,最终导致钢管在狭缝两端出现约45°方向的裂纹,引起钢管混凝土剪切破坏.     

Advanced high-performance liquid chromatography method for highly polar nitroaromatic compounds in ground water samples from ammunition waste sites

An advanced HPLC-photodiode array detection method for the determination of 12 selected highly polar nitroaromatic compounds in ground water samples of ammunition waste sites has been developed and validated. After solid-phase extraction the limits of detection were in the range 0.1–0.5 μg/l. To prove the applicability of the method to other polar nitroaromatic compounds the retention time of another 32 polar compounds under the specified chromatographic conditions were determined and their UV spectra recorded. To review the method, interlaboratory comparisons were performed with a spiked and a real ground water sample.