Predictions of nitrate diffusion in sediment using horizontal attenuated total reflection (HATR) by Fourier transform infrared (FTIR) spectrometry

Using a novel and simple method based on horizontal attenuated total reflection (HATR) by Fourier transform infrared (FTIR) spectrometry, the effective diffusion coefficient, De, of nitrate in a contaminated anthropogenic sediment was estimated as 7.34 x 10(-6)cm2 s(-1). This method, which requires as little as 1 mL of sediment sample, was able to measure the De of a chemical species with a reproducibility of +/-3% in about 5h. Based on this De and a pre-determined nitrate reduction rate, the profiles of nitrate concentration in two sediment columns were satisfactorily predicted from a mathematical model. Results showed that the profile in this aged sediment depended mainly on the diffusion of nitrate and, only to a much lesser degree, the rate of nitrate reduction. Measurements in 55 anthropogenic sediment samples collected from five locations and various depths of a contaminated site further showed that the De of nitrate increased linearly with the water content of the sediment, but decreased with the sediment density. The technique demonstrated in this study shall be applicable for the risk assessment of toxic pollutants in contaminated sediments, and for planning the spatial and time intervals of nitrate injection strategy in bioremediation.     

Speciation of selenium in plant water extracts by ion exchange chromatography-hydride generation atomic absorption spectrometry

Determination of selenium (Se) speciation in plants is important in studying the bioavailability and toxicity of Se in Se-contaminated soil/sediment. In this study, we used an anion exchange resin (Dowex 1-10X) to separate Se into non-amino acid organic Se, Se-amino acids, selenite (Se [IV]) and selenate (Se [VI]) in a plant (Stanleya pinnata) extract. The hydride generation atomic absorption spectrometry (HGAAS) was used to determine concentrations of these Se compounds in plant extracts. Results showed that Se compounds can be quantitatively separated by the resin column. Recovery of five spiked standard Se compounds (trimethylselenonium ion (TMSe+), dimethylselenoxide (DMSeO), selenomethionine (Semet), Se [IV] and Se [VII]) in the plant extract ranged from 92.9 to 103%. Water extractable Se accounted for 60.4-72.6% of the total Se in the plant. Among the soluble Se compounds in the plant extract, Se-amino acids were 73-85.5%, Se [VI] ranged from 7.5 to 19.5% and non-amino acid organic Se was less than 7%. Se [IV] in most samples was below the detection limit (1 microg/g). This study showed that considerable amounts of the accumulated Se [VI] in the plant was metabolized to Se-amino acids during growth of the plant.     

简易自动喷水灭火系统在中小型场所中的应用

通过中小型场所的火灾实体模拟试验,说明了在中小型场所中设置简易自动喷水灭火系统的可行性和重要性。     

重庆菜袁路隧道模拟设计

本文论述应用平面变形条件下的模型试验结果,分析研究重庆菜袁隧道的初步设计,确定喷射混凝土和岩石锚杆的尺寸和二次衬砌的厚度,以及选择适合的施工方法。     

建筑科学“三个走向”的发展趋势——走向自然共生、走向公共大众、走向地域文化

本文提出建筑科学大范围内发展趋势的“三个走向”,即走向自然共生、走向公共大众、走向地域文化,并以新世纪的新建筑实例说明这“三个走向”的发展趋势,这也是落实可持续发展战略的中心内容。     

北京远南大厦设计及其成败得失

介绍了北京南大厦供暖，空调通风，机械排风以及防排烟系统的设计概况，总结了设计中的成功经验，并结合运行情况，提出了一些在设计，生产，施工安装中应注意的问题。     

Effects of Air Inlet Configuration on Forced-Ventilation Enclosure Fires on a Naval Ship

The effects of air inlet configuration on pool fire behavior in a mechanically ventilated cabin were investigated. The closed cabin used was a model of a certain machinery cabin on a naval ship. Two air inlet configurations of one vent and two vents were taken into account together with five different elevations of air inlet. In one-vent cases, mass loss rate and gas temperature were lower and oxygen concentrations were higher than those of two-vent cases. With the increase of air inlet elevation, a sudden drop in average mass loss rate and peak temperature were found in the two-vent cases at the air inlet elevation of 1.56 m. In one-vent cases, a similar drop in average mass loss rate was found at the air inlet elevation of 0.88 m, while the peak temperature was almost unaffected by inlet elevation. According to temperature profiles and the characteristic parameter of the smoke layer stability, the formation of the smoke layer was destroyed by increasing the air inlet elevation or reducing the air inlets, and furthermore a more uniform distribution could be found. For the current cabin, the one-vent case with a lower air inlet elevation was recommended for smoke control, and the inlet should be set away from the essential equipment and the entrances of the cabin.     

GE板形模型的功能及应用

梅钢热轧板厂于2002年引进了先进的凸度仪、平直度仪及GE板形模型,采用模型对窜辊量与弯辊力进行设定与闭环控制,板形质量有了量化指标与控制手段,通过几年的应用与实践,对板形模型的工作原理有了一定了解,文章论述了模型的设定策略、分配策略及控制策略,并阐述了该模型在负荷分配的优化、轧辊磨损量的优化、F4～F6工作辊原始辊型的优化及轧制计划的优化等方面的应用.     

Structure and electrochemical properties of titanate perovskite with in situ exsolution as a ceramic electrode material

Journal of Electroceramics - In this work, the structure and electrochemical properties of titanate ceramics with in situ Ni exsolution are investigated to identify the structure-performance...     

闵行LNG汽车加气与灌装示范站低温预冷技术探讨

LNG(液化天然气)站的低温设备及工艺管道预冷是场站投产前的关键环节,以上海市闵行LNG汽车加气与灌装示范站工程站内低温设备及工艺管道预冷施工为例,分析阐述了LNG场站预冷的目的和原则,预冷的关键技术以及预冷后的注意事项等,并对工程进行总结归纳,对后续类似工程施工有一定指导作用。