聚硅酸钛制备及其助凝特性

采用在活化硅酸制备过程中加入适量Ti Cl4的方法,试制了一种新型无机高分子助凝剂—聚硅酸钛。研究了不同[Si]/[Ti]条件下制备的聚硅酸钛在固定p H值的水中分散物的粒径和Zeta电位随着活化时间的变化趋势,并与活化硅酸作比较。结果表明,在Si/Ti=20,活化48 h的条件下能制备出较为稳定的聚硅酸钛。与活化硅酸相比,聚硅酸钛在水中的分散物具有较大的粒径和更高的Zeta电位。通过对比制备的活化硅酸和聚硅酸钛的红外图谱发现,聚硅酸钛中有TiO-Si键,证明钛离子参与了聚合反应,新生成的化学键提高了它的聚合度和稳定性。采用硫酸铝为混凝剂,聚硅酸钛为助凝剂进行混凝除浊实验。测定了絮凝体的Zeta电位和混凝沉淀后的上清液浊度,研究了硫酸铝投加量和混凝p H对聚硅酸钛助凝效果的影响。结果表明,投加适量的聚硅酸钛助凝剂,明显提高了混凝除浊效果且拓宽了有效混凝p H值的范围。     

Preparation and Characterization of Collagens from the Skin of Northern Snakehead (<Emphasis Type="Italic">Channa argus)</Emphasis>

Channa argus, a type of snakehead fish native to China, is a popular food fish in certain Asian countries but is a known destructive invasive species in the US. In this study, the two collagens, i.e. acid-soluble collagen (ASC) and pepsin-solubilized collagen (PSC), were obtained from C. argus skin. The yield of ASC was 28.0% and that of PSC was 16.8% on the dry bases. The collagens were identified as the collagen of type I by SDS–PAGE patterns. The Tds were approximately 27.0?°C. Similar ultraviolet spectra of both collagens were observed. Fourier Transform infrared spectra indicated PSC structure had a little change due to the loss of terminal domains by pepsin digestion. The results of XRD proved that the two collagens retained their helical structures. The results suggest that the collagens isolated from C. argus can potentially be alternative sources of vertebrate collagens for use in the food and other industries.     

Distribution Characteristics and Implication of n-alkanes in Soils and Plants in Alpine Meadow

Russian Journal of Ecology - The present study was conducted to investigate the n-alkane composition of typical alpine meadows. Plant and soil samples were collected and analyzed to characterize...     

Precursors and potential sources of ground-level ozone in suburban Shanghai

• Air masses from Zhejiang Province is the major source of O₃ in suburban Shanghai. • O₃ formation was in VOC-sensitive regime in rural Shanghai. • O₃ formation was most sensitive to propylene in rural Shanghai. A high level of ozone (O₃) is frequently observed in the suburbs of Shanghai, the reason for this high level remains unclear. To obtain a detailed insight on the high level of O₃ during summer in Shanghai, O₃ and its precursors were measured at a suburban site in Shanghai from July 1, 2016 to July 31, 2016. Using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model and concentration weighted trajectories (CWT), we found that Zhejiang province was the main potential source of O₃ in suburban Shanghai. When the sampling site was controlled by south-western winds exceeding 2 m/s, the O₃-rich air masses from upwind regions (such as Zhejiang province) could be transported to the suburban Shanghai. The propylene-equivalent concentration (PEC) and ozone formation potential (OFP) were further calculated for each VOC species, and the results suggested that propylene, (m+p)-xylene, and toluene played dominant roles in O₃ formation. The Ozone Isopleth Plotting Research (OZIPR) model was used to reveal the impact of O₃ precursors on O₃ formation, and 4 base-cases were selected to adjust the model simulation. An average disparity of 18.20% was achieved between the simulated and observed O₃ concentrations. The O₃ isopleth diagram illustrated that O₃ formation in July 2016 was in VOC-sensitive regime, although the VOC/NO_x ratio was greater than 20. By introducing sensitivity (S), a sensitivity analysis was performed for O₃ formation. We found that O₃ formation was sensitive to propylene, (m+p)-xylene, o-xylene and toluene. The results provide theoretical support for O₃ pollution treatment in Shanghai.     

Manganese-modified biochar for highly efficient sorption of cadmium

Environmental Science and Pollution Research - In this study, corn stalk was modified by manganese (Mn) before (MBC1) and after (MBC2) pyrolysis at different temperatures (400~600&nbsp;°C)...     

Electrocatalytic oxidation of PCP-Na by a novel nano-PbO2 anode: degradation mechanism and toxicity assessment

Environmental Science and Pollution Research - This study aims at investigating the electrocatalytic oxidation of sodium pentachlorophenate (PCP-Na) using a novel nano-PbO2 powder anode. The...     

好氧触媒在造纸法再造烟叶污水处理中的应用分析

本文围绕好氧触媒在造纸法再造烟叶污水处理中的应用展开分析。如对好氧触媒在再造烟叶污水处理中的应用必要性及好氧触媒作用原理予以介绍,并对好氧触媒在造纸法再造烟叶污水处理中应用展开试验。     

阿勒泰地区雾的气候特征与变化趋势及其对人体的影响研究

利用1961年-2012年阿勒泰地区气象观测资料,对雾的时空分布特征和变化趋势进行分析。结果表明:阿勒泰地区雾日数在时间分布上,初春的3月出现最多;冬季(12月-翌年2月)雾出现的比例最高,占37.6%。20世纪80年代年雾出现日数最多,2000年至今最少。阿勒泰地区雾日数在空间分布上也不是很均匀,区域性为西部的吉木乃、哈巴河县最多,东部的富蕴、青河县最少。阿勒泰地区雾出现日数年变化率与各县站的变化趋势一致,均呈明显的下降趋势,在1966年出现了减少的突变现象。R/S方法分析表明,各县站未来的年雾出现日数仍会呈减少趋势,雾天对人体有一定的影响。     

表观遗传学机制与空气污染的健康效应

空气污染是一个全球性的问题,并且具有深远的环境影响。暴露于空气污染会对人体健康产生许多不同的影响,理解空气污染的健康效应又是一个复杂命题,既要考虑不同类型的污染物同时也要考虑相关疾病的复杂性。然而越来越多的研究表明,表观遗传学在空气污染相关疾病的发生、发展中发挥着重要的作用。空气污染物可引起DNA甲基化、组蛋白修饰和miRNA表达等表观遗传学改变,这种改变往往发生在疾病产生的早期,因此相关研究不仅可以了解疾病的发病机制,而且还为疾病早期诊断和预防筛选可能的标志物。本文综述了表观遗传学的几种修饰方式和空气污染物造成不良健康损伤机制的一些研究进展。