Advanced anticorrosive coatings prepared from electroactive polyimide-TiO2 hybrid nanocomposite materials

In this study, we present the first preparation and corrosion protection studies of a series of electroactive polyimide-TiO₂ (EPTs) hybrid nanocomposite materials containing conjugated segments of electroactive amino-capped aniline trimer (ATs) and TiO₂ nanoparticles of ∼10 nm in diameter. Redox behavior of as-prepared EPTs hybrid materials was identified by electrochemical cyclic voltammetry (CV) studies. Higher concentration of TiO₂ component in as-prepare corresponding EPTs was found to reveal better corrosion protection effect on cold-rolled steel (CRS) electrode based on sequential electrochemical corrosion measurements in 5 wt.% NaCl electrolyte. Enhancement of corrosion protection of EPTs coatings on CRS electrode could be interpreted by following three possible reasons: (1) Electroactive polyimide (EPI) could act as a physical barrier coating. (2) The redox catalytic capabilities of ATs units existed in EPTs may induce the formation of passive metal oxide layers on CRS electrode. (3) The well-dispersed TiO₂ nanoparticles in EPTs matrix could act as effective hinder to enhance the oxygen barrier property of EPTs.     

Effective monitoring of corrosion in reinforcing steel in concrete constructions by a multifunctional sensor

A novel multifunctional sensor is developed for in situ and non-destructive monitoring of the corrosion current and open circuit potential of reinforcing steel, as well as the pH and Cl⁻ concentration of concrete. The pH and Cl⁻ sensors show good responses to the pH and Cl⁻ concentration of concrete pore solutions, respectively, and are able to monitor both the carbonization process of concrete and the ingress of Cl⁻ in concrete. Combined with measurements of the corrosion potential and corrosion current density, as well as the EIS spectra of reinforcing steel in concrete, this study demonstrates that the pH and the Cl⁻ concentration of concrete are two of the most crucial factors that determine the corrosion of reinforcing steel in concrete. The corrosion tendency and corrosion rate of reinforcing steel largely depend on the chemical environment in the concrete. The multifunctional sensor is a powerful tool for in situ monitoring corrosion of steel in concrete, and provides accurate details of the chemical condition of the concrete pore solution and the corrosion status of the reinforcing steel in concrete. These are essential for corrosion predictions and service life evaluations of concrete constructions.     

Experimental investigation on the dynamic responses of vented hydrogen explosion in a 40-foot container

To investigate the structural dynamics of a container subjected to a vented hydrogen explosion, 48 field tests were conducted in a 40-foot container with roof vents and an end vent. The effects of the hydrogen concentration, ignition position, and obstacles on the evolution of the dynamic responses were investigated. Three stages were generally observed for displacements: (1) At the stage of the vent rupture, the displacement could be approximated as a quasi-static response, and there was a linear relationship between the peaks of positive overpressure and displacement. (2) Structural deformation appeared as reciprocating vibration at the stage of Helmholtz oscillation. (3) The structure exhibited relatively weak irregular fluctuation when high-frequency acoustic oscillation occurred. Two types of the structural acceleration with low and high amplitudes resulting from Helmholtz oscillation and acoustic oscillation, respectively, were clearly observed. For the end-vented explosion, multiple peaks were observed for the displacement at the quasi-static stage due to the rupture, discharge, and external explosion. Moreover, the displacement was sensitive to hydrogen concentration, whereas the number of obstacles and the ignition position had significant influences on the peak acceleration for roof venting. This work conducted the fundamental explanation for the evolution law of structural responses induced by vented hydrogen explosions from the perspective of structural dynamics and enriched the experimental accumulation in a large-scale container with congestion in this field.     

分布式项目管理的项目模板管理与信息重用

新环境下的分布式项目管理系统要求完善项目计划制定流程，将个人计划和集体计划灵活结合，同时提高已有项目信息的重用能力。这里首先提出基于XML的项目模板模型，指出该模型能够作为个人项目计划信息的载体，并能够和分布式项目计划信息互相转化，从而既满足个人项目计划和集体项目计划相互转化的要求，也能满足已有项目计划重用的要求。其次开发了集成于分布式项目管理系统的项目模板管理系统，给出功能设计。最后介绍了项目模板管理系统的一个实际使用案例。     

In situ measurement of Cl- concentrations and pH at the reinforcing steel/concrete interface by combination sensors

This paper presents an in situ, nondestructive method of monitoring Cl- concentrations and pH values at the steel/concrete interface. The Ag/AgCl electrodes prepared by the electrochemical anodization and the Ir/IrO2 electrodes prepared by thermal oxidation in carbonate served as Cl- concentration and pH sensors, respectively. The potentiometric response of the Ag/AgCl electrode to the logarithm of Cl- concentrations ranging from 1 x 10(-4) to 2 M in saturated Ca(OH)2 solution simulating the inner electrolytic medium of concrete shows good linearity. The Ir/IrO2 electrode also exhibits an ideal Nernstian response in the range of pH 1-14. The Ag/AgCl and Ir/IrO2 electrodes were combined into a multiplex Cl-/pH sensor, and the sensor was embedded in concrete close to the steel/concrete interface to realize an in situ and long-term measurement of Cl- concentrations and pH values. The results indicate that the combined sensor is robust and sensitive enough to in situ measure Cl- concentrations and pH quantitatively at the steel/concrete interface, which is of indispensable importance to the study of corrosion and protection of the steel in concrete.     

利用金属钆测量热中子通量的实验研究

研究了一种测量热中子通量的新方法,利用金属钆与热中子反应产生的次级γ射线来确定热中子通量。使用两个NaI探测器进行符合测量,设计了对伽玛射线和散射中子的良好屏蔽体。经过对本底和钆样品的多次测量,对钆与中子反应产生的伽玛能谱进行了分析,计算出了中子与钆反应产生的计数率(样品净计数率),其最大值达到2.74 Hz,从而证实了这种方法的可行性。     

Some critical structure factors of titanium oxide nanotube array in its photocatalytic activity

A highly ordered TiO2 nanotube array on Ti substrate was fabricated by using an electrochemical anodic oxidation method. The morphology, crystalline phase, and photoelectrochemical property of the nanotube array were characterized. The photocatalytic activity of the nanotube array was evaluated by the decolorization of methyl orange in aqueous solution using the different light sources. The effects of structure and morphology of the nanotube array on its photocatalytic activity were investigated. It was found that the photoabsorption behavior of the TiO2 nanotube film depended on the structures of the nanotube array. The nanotube array films exhibited a drastically enhanced photocurrent, and a higher photocatalytic activity compared with the TiO2 nanoparticle film prepared by the regular sol-gel method. The experimental results indicated that the film thickness markedly influenced the photocatalytic activity of nanotube array film, and the 2.5 microm-thick TiO2 nanotube array film appeared a maximum photodegradation efficiency to methyl orange. However, for a given nanotube length, the tube diameter was only very slightly affected the photocatalytic efficiency in this work. The explanation for some critical structure factors of TiO2 nanotube array in the photocatalytic activity was discussed as well.     

促肝细胞生长素联合腺苷蛋氨酸治疗慢性重型肝炎疗效观察

目的 观察促肝细胞生长素联合腺苷蛋氨酸治疗慢重肝的疗效。 方法 120 例慢重肝患者随机分成两组, 联合用药组(n =62) 和常规治疗组(n =58)。联合用药组在一般治疗的基础上加用促肝细胞生长素及腺苷蛋氨酸, 常规治疗组采用一般治疗。 结果 促肝细胞生长素联合腺苷蛋氨酸联合用药组肝功能明显改善(P <0.05), 总有效率、显效率明显高于常规治疗组(P <0.05), 病死率明显低于常规治疗组(P <0.05), 早、中期慢重肝炎患者的存活率明显高于常规治疗组(P <0.05)。 结论 促肝细胞生长素联合腺苷蛋氨酸治疗慢重肝具有协同保护肝细胞, 促肝细胞再生的作用, 能明显改善肝功能, 降低病死率。对慢重肝患者应早期、足量使用促肝细胞生长素及腺苷蛋氨酸, 能取得满意的治疗效果。     

矩形波导加载光栅结构的太赫兹振荡器

本文采用矩形波导加载光栅的慢波结构作为太赫兹返波管的高频结构,通过理论分析和电磁仿真研究了该慢波结构的色散特性和互作用阻抗,理论分析结果和仿真结果能很好地吻合。在理论分析的基础上,设计了一个中心频率为340GHz的返波管,经粒子模拟软件计算,在较低电流密度的情况下该返波管输出功率达100mW且可调带宽约30GHz。