Application of Iron Tailings-Based Composite Supplementary Cementitious Materials (SCMs) in Green Concrete

How to treat the iron tailings of mining solid waste with high value is an urgent problem on a global scale. In recent years, the application of iron tailings in the building materials industry has attracted the attention of many scholars. The conversion of iron tailings into green building materials helps achieve carbon neutrality and high-value utilization of solid waste, and promotes sustainable development. Although iron tailings have been extensively studied as supplementary cementitious materials, the performance of concrete is not ideal due to its low activity. In this study, the hybrid supplementary cementitious materials system was prepared by iron tailings, phosphorus slag, and steel slag, and the effects of supplementary cementitious materials type, iron tailings content, iron tailings grinding time, and supplementary cementitious materials content on concrete performance were studied. The compressive properties, iron tailings properties, pore structure, interfacial transition zone, and element distribution of hydration products of concrete were tested by compressive strength tests, X-ray Diffractometer (XRD), X-ray Photoelectron Spectroscopy (XPS), Mercury Intrusion Porosimetry (MIP), Backscattering Electron Tests (BSE), and Energy Dispersive Spectrometer (EDS). The results show that further grinding improves the iron tailings activity. There is a synergistic mechanism between steel slag and phosphorus slag in the composite supplementary cementitious materials, which overcomes the low activity defect of iron tailings and produces concrete with a compressive strength exceeding 40 MPa. The composite supplementary cementitious materials can optimize the interfacial transition zone of the concrete interface and reduce the calcium–silicon ratio of the hydration products. However, it will deteriorate the pore structure of the concrete matrix, cause part of the concrete matrix to be damaged and lead to a loss of compressive strength, and the loss is acceptable. This work broadens the methods of comprehensive utilization of iron tailings and also provides a reference for a more detailed understanding of the properties of iron tailings-based concrete.     

以教学评估为契机培养高素质的药学人才

为迎接教学评估,培养高素质的药学人才,药学教学应从更新观念,加快师资队伍建设,改进人才培养模式,教学方法等方面入手。     

Study on Remote Field Eddy Current Testing Technology for Crack-like Defects in Long Truss Structure of Aircraft

Detection of hidden defects of aircraft long truss structures (aluminum alloy) is a challenging problem. The shape of the aircraft truss structure is complex, and the crack defects are buried in a large depth. Without the restriction of skin effect, remote field eddy current (RFEC) has great advantages in detecting buried depth defects. In this paper, in order to detect the hidden defects of the aluminum alloy aircraft long truss structure, the remote field eddy current probe is improved from two aspects of magnetic field enhancement and near-field signal suppression using the finite element method. The results show that indirect coupling energy is greatly enhanced when the connected magnetic circuit is added to the excitation coil. By adding a composite shielding structure outside the excitation coil and the detection coil, respectively, the direct coupling energy is effectively restrained. As a result, the size of the probe is reduced. By optimizing the coil spacing and probe placement position, the detection sensitivity of the probe is improved. The simulation is verified by experiments, and the experimental results are consistent with the simulation conclusions.     

汉密顿抑郁量表的因素结构研究

目的探索和检验汉密顿抑郁量表在中国抑郁障碍人群中的因素结构。方法采用探索性因素分析和验证性因素分析的方法评价汉密顿抑郁量表在抑郁障碍人群中的因素结构。结果探索性主成分分析显示，汉密顿抑郁量表由8个因子组成，因素负荷为0．428—0．912，与原7因子模型不一致；验证性因素分析也不支持汉密顿抑郁量表的7因子结构模型。结论汉密顿抑郁量表在中国抑郁障碍人群中可能呈现多因子结构，不同人群体可能因子结构不同。     

四川省北川县擂鼓镇家庭结构试点调查:2008年汶川大地震前后对比

目的:客观对比擂鼓镇2008年汶川大地震前后家庭结构情况并分析探讨其原因。方法:于2012年对四川省北川县擂鼓城乡进行深入到户试点调查,将调查结果与采用同样调查方法的2007年数据(调查点包括擂鼓农村)进行纵向对比分析,另就2012年数据横向对比擂鼓城乡间以及羌汉两族家庭结构情况。结果与结论:此次调查的擂鼓城乡与2007年擂鼓农村户均人口均约为4左右。汶川大地震后(2012年)擂鼓农村家庭的户均人数与地震前(2007年)相比减少了7%;擂鼓农村2007年家庭96%为核心、主干与夫妇家庭,地震后(2012年)这个比例下降至80%,扩大和其它家庭显著增加,类型更趋多元化。擂鼓城镇与农村不分民族来看家庭结构差异无统计学意义(P>0.05)。擂鼓农村羌族与汉族对比:家庭规模羌汉差距不大(P>0.05);家庭类型差异有统计学意义(P<0.05),汉族家庭更趋多元化;家庭代际差异有统计学意义(P<0.05),汉族家庭更趋大户型。     

Comparative Analysis of Domestic and International Test Guidelines for Various Concrete Repair Materials

The number of aged bridges among concrete structures is increasing. Therefore, to increase their lifespans, repair and reinforcement schemes ought to be implemented. This study selected various repair materials according to crack-surface treatment, crack-filling, and crack-injection methods. These repair materials were evaluated using various test methods proposed by the Korean Standards and the American Society for Testing and Materials for structure protection, structure restoration, and crack repair; the results were analyzed and compared. Consequently, the structure restoration material exhibited a similar freezing–thawing trend as that of chloride, while also exhibiting similar flexural, compressive, bond, and splitting-tensile strengths. However, chloride yielded performance differences (up to two-fold) depending on the type of material used for comparison. The crack-repair material yielded similar trends only for bond strength but yielded differences (up to 2–4-fold) in tensile, compressive, and flexural strengths depending on the material used for comparison. These results confirmed that crack-repair materials exhibit significant differences in performance depending on the manufacturer compared with structure protection and structure restoration materials. Therefore, it is expected that repair materials appropriate for usability, durability, and structure safety, while also being environmentally friendly, could be used in future bridge repairs based on these test evaluations.     

1985 — 2014年中国7～18岁学生超重与肥胖流行趋势

  目的  探讨儿童期超重肥胖与血管结构损害的关系,为成人心血管病儿童期危险因素的防控提供科学依据。  方法  于2017年11月 — 2018年1月采用方便整群抽样方法,在山东省淄博市桓台县抽取1所公立小学共1 319名6～11岁儿童作为研究对象,根据体质指数（BMI）将其分为正常体重组、超重组和肥胖组;采用协方差分析比较不同BMI分组儿童的颈动脉内 – 中膜厚度（carotid intima-media thickness,cIMT）差异,并应用多因素非条件logistic回归模型分析儿童期超重肥胖对血管结构损害的影响。  结果  在调整了性别、年龄、每日睡眠时间、每日视屏时间、每日蔬菜水果摄入频率、每周碳酸饮料摄入频率、每日体力活动时间、收缩压和舒张压等混杂因素后,协方差分析结果显示,超重组和肥胖组儿童的cIMT分别为（0.469 ± 0.083）和（0.502 ± 0.093）mm,均高于正常体重组儿童的（0.453 ± 0.068）mm（均P < 0.05）;超重组和肥胖组男童的cIMT分别为（0.485 ± 0.082）和（0.521 ± 0.092）mm,均高于正常体重组男童的（0.467 ± 0.070）mm（均P < 0.05）;超重组和肥胖组女童的cIMT分别为（0.449 ± 0.077）和（0.480 ± 0.088）mm,均高于正常体重组女童的（0.437 ± 0.064）mm（均P < 0.05）。多因素非条件logistic回归分析结果显示,超重组和肥胖组儿童发生cIMT增厚的风险分别为正常体重组儿童的3.38倍（OR = 3.38,95 % CI = 1.67～6.86）和17.39倍（OR = 17.39,95 % CI = 9.97～30.35）;超重组和肥胖组男童发生cIMT增厚的风险分别为正常体重组男童的6.41倍（OR = 6.41,95 % CI = 1.61～25.56）和41.73倍（OR = 41.73,95 % CI = 12.58～138.41）;超重组和肥胖组女童发生cIMT增厚的风险分别为正常体重组女童的3.02倍（OR = 3.02,95 % CI = 1.24～7.36）和12.38倍（OR = 12.38,95 % CI = 6.16～24.86）。  结论  超重和肥胖可能是儿童期血管结构损害的重要危险因素,预防和控制儿童期超重肥胖可能会降低早期血管结构的损害。