An EIS study of the influence of imperfections on the corrosion behaviour of an organic coated steel system

Three different coating conditions influencing the quality of a silicon polyester galvanized steel system were investigated by means of EIS. The first aim was to investigate the influence of different types of pores or discontinuities on the corrosion resistance of the above-mentioned coating system. A second aim was to study the influence of mechanical deformation and damage of the coating on the corrosion behaviour of the coating system. Finally, degradation due to ultraviolet exposure was investigated. In each of these investigations it was possible to distinguish different time constants for different electrochemical events in the Bode phase diagram. Since the difference in magnitude of the values of the resistances was large, they could not be distinguished in the Nyquist plots. Therefore, this type of plot was not used in this work. From the build-up of the coating system and the number of time constants deduced from the EIS measurements, it was possible to model the system. From the model, the physical and electrochemical phenomena occurring during the service life of an imperfect organic coating system was explained.     

Alpha-acaridial a female sex pheromone from an alarm pheromone emilting mite Rhizoglyphus robini

The female sex pheromone of Rhizoglyphus robini Claparède (Astigmata: Acaridae) was identified as u7734227/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-acaridial [2(E)-(4-methyl-3-pentenyl)- butenedial], which stimulated males sexually and enhanced the frequency of male mounting behavior. Although a hexane extract of females manifested alarm pheromone activity against tested males due to the presence of the alarm pheromone neryl formate, silica gel column fractions containing u7734227/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-acaridial evoked increased mounting behavior by males at a dose of 0.1 female equivalent. Synthetic u7734227/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-acaridial at a dose of 10 ng showed a peak of activity as a sex pheromone, with a convex dose–response relationship. Its content was determined to be 388 ± 244 ng per female and 163 ± 97 ng per male by GC. This is the first time that two pheromones (the alarm pheromone neryl formate, and the sex pheromone u7734227/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-acaridial) have been demonstrated to be components of the same opisthonotal gland secretion in astigmatid mites. A mechanism for the appropriate expression of the two pheromones by the mites under different conditions is proposed.     

Impact of Structural Factors on Unsteady Combustion Modes of Gasless Systems

Based on the twou56125033007579t/xxlarge8208.gif" alt="dash" align="MIDDLE" BORDER="0">temperature, twou56125033007579t/xxlarge8208.gif" alt="dash" align="MIDDLE" BORDER="0">velocity timeu56125033007579t/xxlarge8208.gif" alt="dash" align="MIDDLE" BORDER="0">dependent model of gasless combustion, taking into account structural transformations related to the force action of the gas filtering in the pores and vitrification and volume variation of the condensed phase during the chemical transformation, selfu56125033007579t/xxlarge8208.gif" alt="dash" align="MIDDLE" BORDER="0">oscillatory combustion modes are studied. Structural transformations are shown to have a pronounced effect on the propagation pattern of combustion waves and can either stabilize or destabilize combustion. The major structural parameters appreciably affecting combustionu56125033007579t/xxlarge8208.gif" alt="dash" align="MIDDLE" BORDER="0">wave stability are the initial porosity, particle size, and pressure.     

Ultra-violet absorption as a tracing technique for sewage dispersion and water masses in two red sea coastal lagoons in Jeddah

The u.v. absorbance is measured in water samples, collected on six successive cruises made within 1 year, from two Saudi sewage-affected fjord-like lagoons in Jeddah (Arbacen and Reayat Al-Shabab). The hydrochemical elements, salinity, phosphate and ammonia are also measured. The horizontal and vertical distribution pattern of u.v. absorbance and that for the other hydrochemical elements are found to coincide with each other to a great extent. The direction of the discharged wastewater spread at the surface can be easily identified. Three distinct water layers are observed. The surface layer is diluted by sewage effluent containing high values of u.v. absorbance, phosphate and ammonia. The intermediary layer has almost the same properties as the water outside the lagoon mouth at the same level where it is less diluted (i.e. less polluted). The third layer at the bottom (old water) where the water is dammed by the sills is more saline. It has exceptionally high values out of the four elements studied. This situation prevails almost throughout the year except during the intermittent flushing periods in winter and early spring, when the stratification is disturbed. The advantage of using u.v. absorbance measurement is that it can be read directly in the water samples without any chemical pre-treatment and so no special training is needed.     

关于一些钢筋构造做法的探讨

钢筋构造做法是在日常的设计及施工中需要每个工程师都重视的问题,本文就钢筋构造做法上的几个容易造成浪费或者模糊的问题进行了探讨,提出这些问题,望引起读者的关注和讨论。     

日本中厚板超声波探伤技术

介绍了日本中厚板超声波探伤技术的发展,并对超声波探伤装置的布置、探伤钢板品种和探伤检测条件进行了分析。     

溶胶-凝胶法合成Gd2O3:Eu纳米晶及荧光性质的研究

采用溶胶-凝胶法合成了Gd2O3:Eu纳米晶.利用X射线衍射,热重及差热分析和荧光光谱等测试手段对Gd2O3:Eu的结晶过程、发光性质进行了研究.XRD结果表明,合成的样品在550℃开始结晶,晶粒随着温度的升高而长大,发光光谱测试表明,宽的主激发峰是由Eu3 电荷迁移态吸收与Gd3 离子的的激发峰重叠而成,主发射峰为610nm,它们的强度随烧结温度的提高而增强.     

类单叶算子的(u+k)轨道闭包

在一定条件下,刻画了类单叶算子的(u+k)轨道闭包,并证明了单叶算子包含在类单叶算子的(u+k)轨道闭包中。     

Vitamin a deficiency modifies response of predatory miteAmblyseius potentillae to volatile kairomone of two-spotted spider mite,Tetranychus urticae

A volatile kairomone of the two-spotted spider mite,Tetranychus urticae, elicits a searching response of the phytoseiid predatorAmblyseius potentillae, only when the predator is reared on a carotenoid-free diet. However, after addition of crystalline u413843675748237/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-carotene or vitamin A acetate to the predator's rearing diet this searching response was absent. Because vitamin A and u413843675748237/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-carotene are indispensable nutrients for diapause induction, the carotenoid-deficient predators increase their fitness by searching for two-spotted spider mites, when other spider mites are unavailable. Two-spotted spider mites, among others, contain the carotenoids required for diapause induction, but are an inferior prey due to the dense webbing they produce. When the predators have carotenoids at their disposal, they do better by searching for other spider mites that are more profitable in terms of reproductive success. Such a prey is the European red spide mite,Panonychus ulmi. The volatile kairomone of this prey elicits a searching response of the predator whether it has a carotenoid deficiency or not.     

常州地区1978 年- 2012 年降水量时空分布特征

利用1978 年- 2012 年26 个雨量站资料, 基于线性回归、小波分析、滑动平均曲线等方法分析了常州地区降水量时空分布特征, 结果表明: 35 年来常州地区降水量总体呈增加趋势, 降水变化存在5 a、10 a 两个主周期; 降水量空间分布不均, 总体呈西南向东北递减的趋势, 全区多年降水存在两个上升中心; 城区降水多于郊区, 20 世纪80- 90年代前期尤为明显。