注浆微型钢管桩体轴向承载特性的试验研究∗

针对注浆微型钢管桩用于桩基工程时的承载与变形性能的研究相对较少,借助室内试验研究钢管直径d和壁厚t、桩体长H、浆体水灰比、钢管表面布孔直径r和间距s等因素对微型钢管桩轴向承载、变形和破坏模式的影响.结果 表明:钢管直径和壁厚是影响微型钢管桩轴向极限荷载的主要因素,随着钢管直径和壁厚增加,极限荷载近似呈线性增加,破坏模式由脆性破坏向延性破坏发展;增加桩长或注浆体水灰比,极限荷载呈减少趋势;当钢管直径与桩径之比增至0.59≤d/D≤0.72时,试验桩长、注浆水灰比和钢管表面布孔形式对轴向极限荷载的影响较小;进而基于桩体轴向承载特性及钢管受力与应变分析,提出了合理桩径比值为0.59≤d/D≤0.72,并提出了微型钢管桩轴向极限荷载计算公式.     

电化学合成的聚合氯化铝的形态特征

采用电解法合成了聚合氯化铝溶液 ,并采用2 7AlNMR法、透射电镜等方法对其形态特征进行了研究 .2 7AlNMR法表明在电化学制备PAC中主要含有铝单体 ,铝的二聚体及Al13形态 .Al13含量与其溶液的碱化度 (B)有关 .在总铝浓度 (AlT)为 2 .0mol L ,B为 2 .2时Al13含量达到最高 ,占AlT 的 70 .2 % ,并在溶液中较稳定存在 .透射电镜实验结果表明 ,电解制备的PAC的粒度分布均匀 ,无团聚现象产生     

亚铵法造纸黑液制取水煤浆添加剂的研究

利用黑液中有效成分 ,经过适当处理制备水煤浆添加剂 ,并且对添加剂的性能进行了测试。结果表明 ,依照该工艺生产的添加剂 ,性能优良 ,能够满足工业实际生产需要     

神经元网络在安全评价中的应用

神经元网络是适于处理模糊信息的数学工具，可以解决安全评价中的许多问题，本文就此进行了探索。     

Na2SO4对古尔班通古特沙漠细沙盐结皮特性的影响

盐晶体胶结土壤颗粒形成的一层盐结皮层质地致密且强度较高,具有较高的抗风蚀能力,在土壤风蚀治理中具有重要作用.盐结皮特性与盐的种类及质量分数有关,为探究w（Na₂SO₄）对结皮特性的影响,选取古尔班通古特沙漠东南缘流动风沙土的主要颗粒（100~200 μm）,于70℃下在烘箱内进行13个w（Na₂SO₄）的12 h胶结试验,即风沙土中w（Na₂SO₄）为0.1%、0.2%、0.5%、1.0%、2.0%、3.0%、4.0%、5.0%、6.0%、7.0%、8.0%、10.0%、12.0%,分析w（Na₂SO₄）对风沙土盐结皮的表观、抗压强度及韧性特征3个抗风蚀能力指标的影响.结果表明:①随着w（Na₂SO₄）的增大,结皮表面颜色由红棕色变为浅红棕色再变为灰白色,表面盐晶越来越多.②w（Na₂SO₄）≤ 3.0%时结皮表面平整,4.0%~7.0%时结皮表面呈现起伏"波浪状",≥ 8.0%时结皮表层遭孔隙应力破坏并脱离土体.③w（Na₂SO₄）≤ 3.0%时,样品抗压强度随着w（Na₂SO₄）的增加呈线性上升;≥ 3.0%时受孔隙压力破坏的影响,结皮抗压强度随w（Na₂SO₄）的增加反而下降.④结皮的韧性与w（Na₂SO₄）存在密切关系,w（Na₂SO₄）≤ 3.0%时,韧性随w（Na₂SO₄）的增加而增大,≥ 3.0%时韧性随w（Na₂SO₄）的增加反而减小.沙漠中风沙土主要组成物质是细沙（100~200 μm）,且主要粒径沙土结皮特性与自然风沙土的结皮最相似.所以,若采用质量分数为3.0%的Na₂SO₄胶结风沙土形成盐结皮,具有较好的抗压强度和韧性,且表面平整无破坏,胶结体具有较好的抗风蚀性能,可用作流动沙地的治理.      

Competitive and cooperative adsorption of arsenate and citrate on goethite

The fate of arsenic in natural environments is influenced by adsorption onto metal (hydr)oxides. The extent of arsenic adsorption is strongly a ected by coexisting dissolved natural organic acids. Recently, some studies reported that there existed competitive adsorption between arsenate and citrate on goethite. Humic acid is known to interact strongly with arsenate by forming complexes in aqueous solution, hence it is necessary to undertake a comprehensive study of the adsorption of arsenate/citrate onto goethite in the presence of one another. The results showed that at the arsenate concentrations used in this study (0.006–0.27 mmol/L), citrate decreased arsenate adsorption at acidic pH but no e ect was observed at alkaline pH. In comparison, citrate adsorption was inhibited at acidic pH, but enhanced at alkaline pH by arsenate. This was probably due to the formation of complex between arsenate and citrate like the case of arsenate with humic acid. These results implied that the mechanism of the adsorption of arsenate and citrate onto goethite in the presence of one another involved not only competition for binding sites, but the cooperation between the two species at the watergoethite interface as well.     

Theoretical and exploratory research on sustainability mental model of the public in China: based on a typical survey in Guangdong province

This article aims to investigate the public’s sustainability mental model (SMM), which can reveal the sustainability dilemma from the public respective, other than enterprise or government. In this article, SMM is defined as one’s cognitive structure, thinking mode, and behavior tendency when someone deals with sustainability issues. After theoretical analysis, the authors developed reliable and valid measures systematically and conducted a typical survey with 581 participants from college students’ families in Guangdong province in China. Based on those samples, the author used the exploratory factor analysis and confirmatory factor analysis to construct a measurement model of SMM, which includes three dimensions, i.e. sustainable cognition, sustainable thinking, and sustainable behavior intention. According to SMM survey and clustering analysis, the results indicate that SMM of those participants is inactive. Even though those samples do not represent the whole country comprehensively, but this survey was sampled typically and they came from around China. So, the authors consider the SMM scores can reflect Chinese people to some extent, leading to the assumption that SMM of Chinese people is not active presently.     

Analysis of antibiotic resistance of Escherichia coli isolated from the Yitong River in North-east China

The concentrations of four types of antibiotics in the Yitong River were detected. The concentration of total coliforms in summer was higher than that in spring. There was a seasonal difference in antibiotic resistance of E. coli. The E. coli in the Yitong River was found to have multiple antibiotic resistance. The Yitong River is one of the largest secondary tributaries of the Songhua River. The area where the Yitong River flows is densely populated and contains the livestock and poultry breeding areas of north-east China. These areas introduce a high risk of antibiotic contamination. In this study, the concentrations of four types of typical antibiotics including quinolones, tetracyclines, sulfonamides, and trimethoprim were determined by solid phase extraction-high performance liquid chromatography. The antibiotic resistance of Escherichia coli caused by antibiotic pollution was investigated. The concentration of total coliforms in the Yitong River was detected by the plate counting method. The antibiotic resistance of E. coli to quinolones, tetracyclines, sulfonamides, and trimethoprim was analyzed by the Kirby-Bauer method. The results showed that the concentration of total coliforms in the summer was higher than that in the spring. There was a seasonal difference in the resistance rate of E. coli to antibiotics except trimethoprim. The antibiotic resistance to fluoroquinolones was relatively low. The resistance rate to tetracyclines was higher during the summer. Moreover, resistance to several antibiotics was observed in all sections. This study provides basic data for research on pollution characteristics and prevention of antibiotic exposure in rivers.     

Comparison of mixing layer height inversion algorithms using lidar and a pollution case study in Baoding, China

Beijing–Tianjin–Hebei area is suffering from atmospheric pollution from a long time. The understanding of the air pollution mechanism is of great importance for officials to design strategies for the environmental governance. Mixing layer height(MLH) is a key factor influencing the diffusion of air pollutants. It plays an important role on the evolution of heavy pollution events. Light detection and ranging(lidar), is an effective remote-sensing tool, which can retrieve high spatial and temporal evolution process within mixing layer(ML), especially the variation of MLH. There are many methods to retrieve MLH, but each method has its own applicable limitations. The Mie-lidar data in Beijing was firstly used to compare three different algorithms which are widely used under different pollution levels.We find that the multi-layer structure near surface may cause errors in the detection of mixing layer. The MLH retrieved based on image edge detection was better than another two methods especially under heavy polluted episode. Then we applied this method to investigate the evolution of the mixing layer height during a pollution episode in December2016. MLH at Gucheng county showed the positive correlation with the concentration of particulate matters during the start of this pollution episode. The elevated pollution level in Gucheng was not associated with MLH's decrease, and the significantly increased particulate matters raised the boundary layer, which trapped the pollutants near the surface.     

镉诱导仔猪睾丸支持细胞氧化酶活性降低及DNA损伤的研究

以仔猪睾丸支持细胞为实验模型,采用二步酶消化法分离支持细胞进行培养。探讨了0、10、20、40、80gmol·L^-1的氯化镉对支持细胞的毒性作用。结果表明：10gmol·L^-1以上的氯化镉有抑制支持细胞生长的作用,并能使支持细胞氧化酶活性下降,造成支持细胞DNA损伤。