竹粉含量对竹浆造纸白泥/聚氯乙烯复合材料性能的影响

以竹粉、竹浆造纸白泥和聚氯乙烯为原料,采用铝酸酯偶联剂对竹粉和竹浆造纸白泥进行改性处理,通过热压成型技术制备竹浆造纸白泥/聚氯乙烯复合材料,研究竹粉含量对复合材料密度、力学性能、尺寸稳定性和阻燃性能的影响,并通过XRD、扫描电镜和红外光谱对竹浆造纸白泥进行表征。结果表明：偶联剂与竹浆造纸白泥产生了化学作用;竹粉含量在一定范围内时,对复合材料的力学性能具有一定的增强效果,但其尺寸稳定性能和阻燃性能随竹粉含量的增加而下降;当竹粉含量为10%时,复合材料的密度为1.03 g·cm-3,拉伸强度为4.84 MPa,拉伸断裂伸长率为2.84%,弯曲强度11.83 MPa,弯曲模量为8 883.33 MPa,24 h TS为1.65%,24 h WA为5.16%,氧指数为38.6%,其综合性能较优,其中氧指数达到国家建筑材料阻燃等级B1级的要求。     

SBBR工艺硝化过程中DO对N2O产生量的影响

利用生物膜序批式反应器(SBBR),考察不同溶解氧(DO)条件下硝化过程中N2O产生及释放过程。研究结果表明:DO浓度增大有利于控制系统中N2O的产生;DO浓度分别为(1.92±0.14)mg/L、(2.34±0.11)mg/L和(2.70±0.11)mg/L时,硝化过程中N2O释放因子(N2O总产量与NH4+-N转化量的比值)分别为5.47%、5.36%和4.77%。分析其原因主要是DO浓度的减小使DO对生物膜的穿透力降低,氧传递能力减弱后生物膜系统内易发生以N2O为产物的氨氧化细菌(AOB)反硝化反应。同时,在研究的3种不同的DO条件下,低DO运行条件更有利于SBBR实现亚硝酸盐型同步硝化反硝化。     

Atmospheric pollution of agriculture-oriented cities in Northeast China: A case in Suihua

Agriculture-oriented cities in Northeastern China have experienced frequent atmospheric pollution events. Deeper understandings of the pollution characteristics, haze causes and effects of management on local air quality are crucial for conducting integrated management approaches for the sustainable development of agriculture-oriented cities. Taking a typical agriculture-dominant city( i.e., Suihua) in Northeast China, we analyzed in detail the characteristics and causes of atmospheric pollution...     

危废填埋项目环境水文地质勘查与分析

文中以宿迁市某危废填埋项目为例,采用水文地质调查、抽水试验、渗水试验等多种水文地质勘查方法,查明了评价区内的环境水文地质条件与特征,获得了预测评价所需的水文地质参数,为地下水环境影响评价提供了基础资料,也作为类似工程的场地环境水文地质勘查工作的参考。     

Landfills in Jiangsu province, China, and potential threats for public health: leachate appraisal and spatial analysis using geographic information system and remote sensing

Waste disposal is of growing environmental and public health concern in China where landfilling is the predominant method of disposal. The assessment of potential health hazards posed by existing landfills requires sound information, and processing of a significant amount of spatial data. Geographical information system (GIS) and remote sensing (RS) are valuable tools for assessing health impacts due to landfills. The aims of this study were: (i) to analyze the leachate and gas emissions from landfills used for domestic waste disposal in a metropolitan area of Jiangsu province, China, (ii) to investigate remotely-sensed environmental features in close proximity to landfills, and (iii) to evaluate the compliance of their location and leachate quality with the relevant national regulations. We randomly selected five landfills in the metropolitan areas of Wuxi and Suzhou city, Jiangsu province, established a GIS database and examined whether data were in compliance with national environmental and public health regulations. The leachates of the sampled landfills contained heavy metals (Pb, As, Cr(6+) and Hg) and organic compounds in concentrations considered harmful to human health. Measured methane concentrations on landfill surfaces were low. Spatial analysis of the location of landfills with regard to distance from major water bodies, sensible infrastructure and environmental conditions according to current national legislation resulted in the rejection of four of the five sites as inappropriate for landfills. Our results call for rigorous evaluation of the spatial location of landfills in China that must take into consideration environmental and public health criteria.     

旅游小贴士

随着人们生活水平的不断提高,很多人已经开始计划甚至在打点行装,准备外出游玩。出门旅游,有很多事项需要特别注意,因为这些都关乎您的健康。     

Interaction of total N-nitroso compounds in environment and in vivo on risk of esophageal cancer in the coastal area, China

Shantou, China, is one of the endemic regions of esophageal cancer (EC) in the coastal areas, but the relationship between the multiple exposures of total N-nitroso compounds (TNOCs) and the high risk of EC to date is unclear. This study is to estimate the potential integrative role of multiple exposures of environmental and endogenous TNOC on the EC risk. We collected randomly the samples of 72 h diet and 24 h urine from 256 healthy male (aged 30-65 years) in the high- and low-risk area for EC, and determined the contents of TNOC and 4 N-nitrosamino acids (NAAs) by a method of chemical fission-Thermal Energy Analyzer (TEA) and gas chromatography--TEA, respectively. We used TNOC and NAAs index to evaluate the integrative effect of multiple TNOC exposures on the EC risk by a logistic model. TNOC intake and urinary TNOC content were higher in the high-risk subjects than that in the low-risk subjects by 1.60 micromol/day and 1.45 micromol/L, respectively. TNOC intake, urinary TNOC content and its interaction were significant factors involved in the higher risk of EC (R(2)=0.685, p=0.000) with predicted Correct Class of 85.6%. The risk of the occurrence of a larger SMR of EC may increase by 4.841-fold for every 1 micromol/day increase in TNOC intake (95% CI 2.370-9.888, p=0.000) and by 4.113-fold for every 1 micromol/L increase in urinary TNOC content (95% CI 2.108-8.023, p=0.000), respectively. The integrally role of multiple exposures of TNOC in environment and in vivo may increase the risk of EC in the coastal areas in eastern Guangdong, China.     

Benchmark dose for cadmium exposure and elevated N-acetyl-β-d-glucosaminidase: a meta-analysis

Environmental Science and Pollution Research - Cadmium (Cd) is a well-known nephrotoxic contaminant, and N-acetyl-β-d-glucosaminidase (NAG) is considered to be an early and sensitive marker of...     

非规则多跨简支梁桥纵向地震反应及参数影响分析

考虑支座非线性和桥墩弹塑性的影响,建立了不等墩高5跨非规则简支梁桥的有限元模型。采用非线性时程分析方法计算了不同地震波输入下多跨简支梁桥的纵向地震反应,研究了非规则多跨简支梁桥邻跨刚度比及上部结构间相互碰撞效应对桥梁纵向地震位移反应和内力反应的影响规律。研究表明,邻跨刚度比对非规则多跨简支梁桥的桥墩剪力、墩底弯矩、墩顶位移、梁体位移、墩梁间相对位移及主梁间相对位移有着显著的影响,并且邻跨刚度相差越大,影响越为显著,更容易使上部梁体发生落梁破坏;考虑桥梁上部结构碰撞效应时,邻跨比对桥梁结构反应的影响受地震波的影响较大,碰撞未必加剧落梁破坏。     

新时期我国区域协调发展进展研究

近年来，随着我国社会和经济改革的逐渐深入，区域协调发展问题日益凸现和发展，成为制约我国社会和经济进一步发展的瓶颈。综述了我国新时期区域协调发展的主要研究进展，展望了地理学在这一领域的发展趋势。