Role of Bipolar Pulsed DBD on the Growth of <Emphasis Type="Italic">Microcystis aeruginosa</Emphasis> in Three-Phase Discharge Plasma Reactor

Algae in drinking water supplies often bring about impact on the water treatment. In this study, a bipolar pulsed dielectric barrier discharge system in three-phase discharge plasma reactor was constructed for investigating its ability to control excessive growth of cyanobacteria, Microcystis aeruginosa. Experimental results show there was almost no change in optical density immediately after the interruption of electrical discharge, but the decreasing trend of optical density, cell density and chlorophyll-a content was obvious during the incubation period, indicating a significant residual effect of electrical discharge process on the algal growth inhibition. Scanning electron microscopy investigation of algae revealed surface damage, apparent leakage of intracellular contents and pores formed after electrical discharge process, which showed that algal cells had no potential to survive and grow. Compared with the control sample, it was observed that electrical discharge on the algal extracellular products has almost no residual effect and the growth rate of algae slightly decreased before three days storage. Hydrogen peroxide was produced by electrical discharge in the μM level and showed a first-order decay. But at such level, the external addition of hydrogen peroxide alone is not likely to cause the residual effect. These results implicated that the growth inhibition of M. aeruginosa was mainly caused by electrical discharge process, and it made the algal cells lose ability to survive, demonstrating the considerable potential of such an alternative process for efficient water purification.     

Some intriguing items in the history of scientific balances

The short survey covers the development of the balance since its invention in the Neolithic era. Scales have been used most probably first as tools in trading, but already in Old Egyptian papyrus its use in techniques is documented. Its theory was cleared by Aristotle and Archimedes and at least at that time it was used as a scientific instrument. Today the balance is still the most widely used instrument in science and there are still improvements.     

沉淀剂和Ag含量变化对甲醛降解性能的影响

采用不同沉淀剂制备CeO₂-Co₃O₄复合金属氧化物载体,通过浸渍负载不同含量Ag获得Ag/CeO₂-Co₃O₄催化剂.借助氮气物理吸附、XRD、Raman和H₂-TPR等手段研究了催化剂的物理化学性质.结果表明：当WHSV=30 000 mL·g^-1·h^-1时,催化剂能表现出良好的催化氧化甲醛性能,在≤ 90℃时实现甲醛的完全转化.草酸沉淀能有效降低Ce-Co氧化物的结晶度,使得Co²⁺含量增加,提供更多的氧空位,促进了氧分子的活化与迁移,从而提高了催化活性.随着Ag含量增加,使得由草酸沉淀制备的Ag/CeO₂-Co₃O₄催化剂的活性增强,且金属与载体间的相互作用也增强,当Ag负载量为1%（重量百分比）时活性最佳.     

飞机撞击建(构)筑物研究进展

飞机撞击重要建(构)筑物会导致灾难性后果。本文从试验研究、理论分析、数值模拟等3个方面对飞机撞击建(构)筑物的国内外研究现状,相关研究难点、需要注意的问题和研究方向及趋势进行总结,包括:缩比试验的系统和验证,飞机撞击力模型,撞击所致局部破坏计算公式,飞机和建(构)筑物的精细化建模,撞击所致振动特性,撞击荷载和火荷载对结构的耦合毁伤效应,一般模型和精细化模型、解耦和耦合方法以及不同数值模拟程序计算结果的对比分析等方面,以期为后续研究提供参考。     

移动简谐荷载作用下桥梁响应的高效计算

在计算移动荷载过桥问题中广泛使用的Newmark方法必须在每一时间步内限制荷载的大小和作用位置都不能改变。精细积分法虽然允许荷载的大小在每一时间步长内发生变化,但是仍假定其作用位置是不变的,未能采取措施以描述荷载沿着桥面的连续移动性。本文提出三种精细积分格式,在每一时间步内不但允许移动荷载的大小按简谐规律连续变化,而且模拟了简谐荷载在空间域的连续移动。通过与Newmark方法和简单问题的解析解进行数值比较,表明用本文提出的方法可以用较粗的结构单元和较大的时间步长而获得很高的计算精度。在精度相同的前提下,计算效率比Newmark方法可提高1~2个数量级。     

The pentacene films on the glass/ITO surface: structure and optical properties

Abstract

The structure, morphology and optical transmittance spectra of pentacene films on the (glass/ITO) surface were studied. The films were grown by two methods - the thermal vacuum deposition (TVD) and pulsed laser deposition (PLD). The electron diffraction pattern from thermally deposited pentacene films confirms their polycrystalline structure while the diffraction pattern of PLD-coated layers has a diffusion character. The results obtained showed that layers deposited by the TVD method has an optical spectrum that is characteristic for the pentacene film in contrary to the layers deposited by the PLD method. It is found a sensitivity of the optical transmittance of pentacene films to the ammonia action, which may be used for development the optical gas sensor.     

Scenario Reduction Algorithms in Stochastic Programming

We consider convex stochastic programs with an (approximate) initial probability distribution P having finite support supp P, i.e., finitely many scenarios. The behaviour of such stochastic programs is stable with respect to perturbations of P measured in terms of a Fortet-Mourier probability metric. The problem of optimal scenario reduction consists in determining a probability measure that is supported by a subset of supp P of prescribed cardinality and is closest to P in terms of such a probability metric. Two new versions of forward and backward type algorithms are presented for computing such optimally reduced probability measures approximately. Compared to earlier versions, the computational performance (accuracy, running time) of the new algorithms has been improved considerably. Numerical experience is reported for different instances of scenario trees with computable optimal lower bounds. The test examples also include a ternary scenario tree representing the weekly electrical load process in a power management model.     

基于BP网络的混凝土耗能器骨架曲线拟合

结合5种混凝土延性柱耗能器在低周期反复荷载作用下的试验数据研究,利用神经网络的工作原理,通过建立神经网络的输入层、隐含层、输出层,确定输入单元、输出单元和隐含层节点数,从而建立了BP神经网络的模型,并根据已有的部分试验数据数据.对网络进行训练,对各种混凝土延性柱耗能器骨架曲线进行了预测拟合,实现混凝土延性柱耗能器骨架曲线的数字化,使其成为具有分析和判断的拟合曲线功能,完整的描绘混凝土延性柱耗能器的骨架曲线,为后续混凝土延性柱耗能器性能研究的仿真模拟提供了可靠的数据模型.结果表明,这种方法是可行的.     

固相萃取-离子色谱-积分脉冲安培法测定人血清中游离氨基酸

比较了磺基水杨酸和无水甲醇沉淀人血清中蛋白质的效果,优化了国产732型阳离子交换树脂进行固相萃取净化的条件和Dionex-600离子色谱分析系统的梯度淋洗条件。用该离子色谱仪检测了谷氨酰胺等14种氨基酸,结果表明,峰面积-浓度的校正曲线的相关系数为0.9900~0.9995,检出限为0.02~0.59mg/L;峰面积的相对标准偏差为1.9%~10.4%;回收率为80.6%~114.8%。     

高效阴离子交换色谱分离-脉冲安培检测法测定烟草料液中的糖、糖醇和醇类化合物

建立了高效阴离子交换色谱分离-脉冲安培检测法测定烟草料液中的糖、糖醇以及醇类化合物的方法。以NaOH为淋洗液,在CarboPac MA1阴离子交换柱上等度分离了肌醇、甘油、丙二醇、半乳糖醇、木糖醇、山梨醇、甘露醇、葡萄糖、果糖、蔗糖、甘露糖和半乳糖等12种化合物。对影响分离和检测的条件进行了优化,并在此优化条件下分析了烟草料液中的糖、糖醇以及醇类化合物。12种化合物的检出限为2.0~216μg/L(25.0μL进样,以3倍信噪比计算检出限)。12种化合物浓度为1~5mg/L的标准溶液连续7次进样的RSD为0.7%~4.3%。方法对烟草料液中12种化合物的加标回收率为80%~108%。方法灵敏、高效、简便、快捷。