Single particle analysis of ambient aerosols in Shanghai during the World Exposition, 2010: two case studies

ATSI Model 3800 aerosol time-of-flight mass spectrometer (ATOFMS) was deployed for single-particle analysis in Shanghai during the World Exposition (EXPO), 2010. Measurements on two extreme cases: polluted day (1st May) and clean day (25th September) were compared to show how meteorological conditions affected the concentration and composition of ambient aerosols. Mass spectra of 90496 and 50407 particles were analyzed respectively during the two sampling periods. The ART-2a neural network algorithm was applied to sort the collected particles. Seven major classes of particles were obtained: dust, sea salt, industrial, biomass burning, organic carbon (OC), elementary carbon (EC), and NH₄-rich particles. Number concentration of ambient aerosols showed a strong anti-correlation with the boundary layer height variation. The external mixing states of aerosols were quite different during two sampling periods because of different air parcel trajectories. Number fraction of biomass burning particles (43.3%) during polluted episode was much higher than that (21.6%) of clean time. Air parcels from the East China Sea on clean day diluted local pollutant concentration and increased the portion of sea salt particle dramatically (13.3%). The large contribution of biomass burning particles in both cases might be an indication of a constant regional background of biomass burning emission. Mass spectrum analysis showed that chemical compositions and internal mixing states of almost all the particle types were more complicate during polluted episode compared with those observed in clean time. Strong nitrate signals in the mass spectra suggested that most of the particles collected on polluted day had gone through some aging processes before reaching the sampling site.     

Enhancing soil aggregation and acetamiprid adsorption by ecofriendly polysaccharides hydrogel based on Ca2+- amphiphilic sodium alginate

Soil aggregation plays an important role in agricultural production activities. However, the structure of soil aggregation is destroyed by the natural environment and unreasonable farming management, resulting in the loss of water, fertilizers and pesticides in soil. At present, hydrogels have been widely reported to promote the formation of soil aggregation. In this paper, amphiphilic calcium alginate (ASA/Ca²⁺) was applied to promote the formation of soil aggregation and enhance pesticide retention. Initially, an ASA was obtained through the one-pot Ugi condensation (a four-component green chemical reaction). Then, ASA/Ca²⁺ hydrogel is prepared by Ca²⁺ cross-linking. The formation of soil aggregation was determined through the Turbiscan Lab Expert stability analyzer, Confocal Laser Scanning Microscope (CLSM), and Transmission Electron Microscope (TEM). And the effect of soil aggregation on acetamiprid environmental behavior was investigated by adsorption kinetics, adsorption isotherms, and leaching. The results shown that the three-dimensional network structure of ASA/Ca²⁺ hydrogel can promote the formation of soil aggregation. Aggregate durability index (ADI) was 0.55 in the presence of ASA/Ca²⁺ hydrogel, indicating that amphiphilic hydrogel can enhance the stability of soil aggregation. The adsorbing capacity of acetamiprid was 1.58 times higher than pure soil, and the release of acetamiprid only about 20% in the presence of ASA/Ca²⁺ hydrogel. These results would be helpful for the formation of soil aggregation and pesticides adsorption on soil aggregation. Thus, ASA/Ca²⁺ hydrogel is likely to improve soil quality, simultaneously it can minimize the mobility of pesticides in the agricultural system.     

Utilization of solidified phosphogypsum as Portland cement retarder

The utilization of the phosphogypsum (PG) as cement retarder is both an economical and an ecological approach to treat this solid waste. Cement using raw PG as retarder has two problems pressing for solution,namely, delaying the setting time and difficulty being fed into the cement mill. The soluble phosphates in PG behave as super-retarder and bring about retarding in the setting process of cement made with PG. Two types of solidified phosphogypsum (SPG) were prepared to solve those two problems. The strength and the water stability of the SPG were good enough to ensure that they may be conveyed easily and fed into the cement mill stably. The cements with SPG had a similar setting time and strength as cement made with natural gypsum (NG). The microstructure of two kinds of SPG were observed with SEM. During factory application of SPG, good techniques and economic benefits were obtained.     

二硫化钼基杂化物对聚合物火灾安全性影响

为改善聚合物材料的火灾安全性,利用二硫化钼(MoS2)的独特性能,结合纳米复合、催化成炭等设计思路,采用共沉淀法制备CeMnOx-MoS2和CeFeOx-MoS2双金属氧化物-MoS2纳米杂化物,并将其分别应用到2种典型聚合物(聚氨酯和环氧树脂)中.结果 表明:2种杂化物均匀分散在聚合物基体中,可有效延缓聚合物材料的热...     

Experimental investigation into the oxidation reactivity, morphology and graphitization of soot particles from diesel/n-octanol mixtures

Aiming to investigate the impacts of n-octanol addition on the oxidation reactivity, morphology and graphitization of diesel exhaust particles, soot samples were collected from a four-cylinder turbocharged diesel engine fueled with D100（neat diesel fuel）, DO15（85% diesel and 15% n-octanol, V/V） and DO30（70% diesel and 30% n-octanol, V/V）. All tests were conducted at two engine speeds of 1370 and 2150 r/min under a fixed torque of 125 N ·m. The soot properties were characterized by thermogravimet...     

Absence of metallothionein 3 expression in breast cancer is a rare but favorable marker that is under epigenetic control

Cadmium (Cd²⁺), a known carcinogen, mimics the effects of estrogen in the uterus and mammary gland suggesting its possible involvement in the development and progression of breast cancer. This lab showed through analysis of a small set of archival human diagnostic specimens that the third isoform of the classic Cd²⁺ binding protein metallothionein (MT-3) is not expressed in normal breast tissue, but is expressed in some breast cancers and that expression tends to correlate with a poor disease outcome. The goals of this study were to verify that overexpression of MT-3 in a large set of archival human diagnostic specimens tends to correlate with poor disease outcome and define the mechanism of MT-3 gene regulation in the normal breast epithelial cell. The results showed that MT-3 was expressed in approximately 90% of all breast cancers and was absent in normal breast epithelium. The lack of MT-3 staining in some cancers correlated with a favorable patient outcome. High frequency of MT-3 staining was also found for in situ breast cancer suggesting that MT-3 might be an early biomarker for breast cancer. The study also demonstrated that the MCF-10A cell line, an immortalized, non-tumorigenic model of human breast epithelial cells, displayed no basal expression of MT-3, nor was it induced by Cd²⁺. Treatment of the MCF-10A cells with the demethylation agent, 5-aza-2′-deoxycytidine, or the histone deacetylase inhibitor, MS-275, restored MT-3 mRNA expression. It was also shown that the MT-3 metal regulatory elements are potentially active binders of protein factors following treatment with these inhibitors suggesting that MT-3 expression may be subject to epigenetic regulation.     

Aqueous high‐temperature chemistry of arsenic‐containing compounds in water at 300°C

Arsenic compounds, and especially organo‐arsenic derivatives, are highly toxic and many have been manufactured as chemical warfare agents. This study was designed to provide background information relevant to the potential application of aquathermolysis techniques for the detoxification of such potent military warfare agents. Six arsenic‐containing compounds with structural features which mimic known agents were studied in neutral superheated water: 4‐aminophenylarsine oxide, 4‐arsanilic acid, 4‐nitrophenylarsonic acid, 5, 10‐dihydro‐10‐ethylphenarsazine, tetraphenylarsonium chloride hydrate, and (3‐cyanopropyl)dimethyl(2‐phenethyl)arsonium bromide. Most of these compounds were moderately susceptible to hydrolysis for 1h at 300°C. o‐ and p‐Aminosubsituted arsenic compounds were more reactive than compounds with an electron‐withdrawing group substituent. Aromatic C—As bonds were more resistant to cleavage than aliphatic C—As bonds.     

液氮冻融破碎生物污泥制备生物絮凝剂

利用城市剩余生物污泥,采用液氮冻融破碎、提取液提取的方法制备了生物污泥絮凝剂。对絮凝剂的制备条件及其絮凝性能进行了研究,结果表明:采用液氮冻融破碎,pH为1.0的稀盐酸溶液作为提取液提取所制备的絮凝剂,对高岭土悬浮液的絮凝效率可达98.5%。液氮冻融破碎的次数对絮凝剂制备没有明显影响。同时考察了絮凝剂投加量以及絮凝体系的pH对絮凝剂絮凝活性的影响。     

松花江哈尔滨江段高锰酸盐指数的遥感反演

以松花江哈尔滨江段高锰酸钾指数为研究对象,于2012年7月14～15日,测定了11个断面31个采样点的高锰酸钾指数数据,同步获取了采样点水质高光谱反射率数据,使用相关性统计分析和多元非线性回归分析方法,用其中21个样点数据构建反演模型,得到模型决定系数(R2)为0.890,用10个样点数据进行验证,得到预测值的均方根误差(RMSE)为0.439 mg·L-1,平均绝对偏差(MAD)为0.365 mg·L-1,平均绝对偏差率(MADR)为8.43%.     

北京地区典型二噁英(PCDDs)及多氯联苯(PCBs)的长距离传输潜力——基于TaPL3模型的应用研究

以典型二噁英(PCDDs)和多氯联苯(PCBs)为研究对象,利用TaPL3模型模拟计算了稳态假设下北京地区4种PCDDs和7种PCBs通过大气和水体的长距离迁移潜力(LRTP)和总持久性(Pov),比较了不同氯取代数的特征迁移距离(CTD)和Pov的大小,分析讨论了二者之间的关系,并以PCB180为例对关键参数进行了灵敏度分析.结果表明,4种PCDDs和7种PCBs在北京地区通过大气的CTDair范围分别为714—874 km和1771—8517 km,Povair范围分别为1422—5169 d和1210—35687 d;通过水体的CTDwater范围分别为1232—1385km和643—4222 km,Povwater范围分别为4900—5618 d和1831—35922 d.对于PCDDs,CTD和Pov基本上随着氯取代数目的增加而增大;对于PCBs,Pov的变化规律与PCDDs类似,而通过大气和通过水体的CTD的变化规律不同.CTD和Pov没有表现出直接的关系.与国内外同类研究相比,北京地区的结果和国外接近,但高于兰州地区通过大气的CTDair,低于通过水体的CTDwater.