Inhibition of stress corrosion cracking in 304 stainless steel through titanium ion implantation

The effects of titanium ion implantation on the stress corrosion cracking (SCC) behaviour of 304 austenitic stainless steel were studied. Slow strain rate tests (SSRTs) were conducted on 304 steel in air and in 5?wt-% NaCl solution. The microscopic effects of ion implantation were evaluated by Stopping and Range of Ions in Matter Procedures (SRIM). Fracture morphologies and microstructures were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The fracture surfaces illustrate that ion implantation significantly inhibits the corrosion pits that initiate SCC. A dense passive film, which inhibits SCC, was formed during the ion implantation process. SCC initiation was restrained due to the dense dislocation nets that were generated by titanium ion implantation.

Highlights

• Ion implantation inhibits SCC susceptibility.

• The lack of Cr at the grain boundary leads to the expansion of SCC along the grain boundary.

• Implantation-induced damage leads to high-density dislocations.

• The surface was amorphised due to high-density dislocations.

     

工业厂房可靠度评估的一种新方法

工业厂房的多样性使得其组成部分的可靠度、耐久性、安全性、适用性、成新度等评估等级往往不在同一范围内 ,这给工业厂房的等级评估带来困难。本文利用物元分析法和层次分析法的特点 ,将物元分析和层次分析法有机的结合起来建立工业厂房综合评估模型 ,并用该模型对某工业厂房可靠度进行了评估 ,评估结果表明该评估方法评估建筑产品可靠度是比较符合客观实际的 ,能够克服传统方法中参评人员的主观不确定性和认识上的模糊性     

Degradation of DBPs' precursors in river water before and after slow sand filtration by photo-Fenton process at pH 5 in a solar CPC reactor

The generation of disinfection by-products during water treatment can be controlled by reducing the levels of precursor species prior to the chlorination step. The Natural Organic Matter (NOM) is the principal organic precursor and conventional removal of pollutants such as coagulation, flocculation and filtration do not guarantee the total NOM removal. In this study the degradation of NOM model compounds (dihydroxy-benzene) as well as the removal of NOM from river water via photo-Fenton process in a CPC solar photo-reactor is presented. The effect of solar activated photo-Fenton reagent at pH 5.0 before and after a slow sand filtration (SSF) in waters containing natural iron species is investigated and the details reported. The results showed that the total transformation of dihydroxy-benzene compounds along a mineralization higher than 80% was obtained. The mineralization of the organic compounds dissolved in natural water was higher than in Milli-Q water, suggesting that the aqueous organic and inorganic components (metals, humic acids and photoactive species) positively affect the photocatalytic process. When 1.0 mg/L of Fe³⁺ is added to the system, the photo-Fenton degradation was improved. Therefore the photo-Fenton reagent could be an interesting complement to other processes for NOM removal. Comparing the response of two rivers as media for the organic compounds degradation it was observed that the NOM photo-degradation rate depends of the water composition.     

物料群颗粒与振动床面碰撞运动理论分析

从两颗粒碰撞理论出发,推导出了振动床面上物料群颗粒碰撞运动 规律,建立了物料群颗粒与振动床面碰撞后某颗粒运动速度与恢复系数、 物料层数、床面速度之间的数学模型,并对不同的恢复系数进行了详细 分析:为解决筛分、分选、给料等工程中实际的问题奠定了理论基础。     

物元分析法对土壤重金属质量评价的研究及改进

本文主要针对物元分析法在土壤重金属质量评价中的应用进行研究,并以东莞市12个监测点的土壤重金属监测数据为例对土壤重金属污染现状进行评价。同时,深入剖析物元分析评价法,对其方法的不足进行改进,研究结果证明,采用权重和毒性相结合的"基于加权毒性的物元分析法"是一种合理的计算方法,评价结果可靠、准确,是一种适用于土壤重金属评价的新方法。     

Matter Timed

At best, the ageing of materials is regarded as lending a patina to historic buildings. In reality, however, materials often age disgracefully and unevenly, requiring a high level of maintenance and refurbishment. What if materials could be engineered and integrated into buildings not only to enhance but to heal? Martina Decker , Assistant Professor in the College of Architecture and Design at the New Jersey Institute of Technology (NJIT), looks at pioneering research that is being undertaken into performative, time-dependent materials.     

Beyond Electromagnetic and Mechanical World‐views: J. Larmor's Models of Matter and Energy in the Early 1890s

In the last decades of the nineteenth century, the relationship between matter and energy was widely debated, mainly in the context of electromagnetic theories. In the 1880s and early in the 1890s, Larmor swung between Helmholtz and Maxwell's theoretical models. In 1893, he put forward a renewed Maxwellian approach centred around the relationships between electricity and matter, and between electric and chemical phenomena. Both the electromagnetic theory and the theory of matter were based on the assumption of a rotationally elastic aether. In 1894, he introduced the ‘electron’, namely a subatomic unit of matter and electric charge, stemming from a continuous aether as a knot of rotational energy. He tried to connect continuous models to discrete models; he tried to connect the intimate nature of matter to the intimate nature of energy. In particular, he aimed at unifying physics, starting from a primitive medium, whose motions could produce regular structures and regular perturbations. New bold hypotheses, like electrons' ‘steady motion’ inside atoms, were the price Larmor had to pay for that integration. I find that Larmor's theoretical contribution cannot be qualified as an electromagnetic world‐view, just because he tried to go beyond a purely mechanical or a purely electromagnetic foundation of physics.     

高空气球探测暗物质试验的数据采集测试系统

德国亚琛工业大学(RWTH-Aachen)作为AMS-01和AMS-02的参与者计划在AMS实验无法继续的基础上,利用高空探测气球进行暗物质的探测。该项目就是为了研究暗物质而开展的试验,论文介绍Positron Electron Balloon Spectrometer(PEBS)的数据采集部分,前端探测器部分可以查阅AMS的相关网页。     

Kinetics of Natural Organic Matter as the Initiator,Promoter, and Inhibitor,and Their Influences on the Removal of Ibuprofen in Ozonation

Natural organic matter (NOM) can simultaneously act as the initiator, promoter and inhibitor in water ozonation. This study presents an explicit method that can be used to determine these rate constants via the integration of the transient steady-state hydroxyl radical (?OH) model, the R_ct concept and the pseudo first-order ozone decomposition model. The theoretical background of this method was provided, and the method was validated with model compounds. The rate constants of three NOM isolates were determined using the developed method. With these rate constants, the influences of NOM on the degradation of ibuprofen, an ?OH-reactive pharmaceutical compound, can be quantitatively described. [Supplementary materials are available for this article. Go to the publisher's online edition of Ozone Science &; Engineering for the following free supplemental resources: tables, figures, and equations.]     

福建蜂蜡非皂化部分组成分析研究

作者采集了福建省八地区的蜂蜡样品，对其组成进行系统的分析研究－皂化后分离出的非电皂化部分^[1]（高级脂肪醇C22－32），通过红外光谱和质谱以及气相色谱分析研究其组成结果，可以确定高级脂肪醇C22－32的分布及其结果，利于以其为原料生产正－三十烷醇的厂家对不同地区蜂蜡的选取。