Genotoxicity of ferric oxide nanoparticles in Raphanus sativus: Deciphering the role of signaling factors, oxidative stress and cell death

We have studied the genotoxic and apoptotic potential of ferric oxide nanoparticles(Fe_2O_3-NPs) in Raphanus sativus(radish).Fe_2O_3-NPs retarded the root length and seed germination in radish.Ultrathin sections of treated roots showed subcellular localization of Fe_2O_3-NPs,along with the appearance of damaged mitochondria and excessive vacuolization.Flow cytometric analysis of Fe_2O_3-NPs(1.0 mg/m L) treated groups exhibited 219.5%,161%,120.4% and 161.4% increase in intracellular reactive oxygen species(ROS),mitochondrial membrane potential(ΔΨm),nitric oxide(NO) and Ca2+influx in radish protoplasts.A concentration dependent increase in the antioxidative enzymes glutathione(GSH),catalase(CAT),superoxide dismutase(SOD) and lipid peroxidation(LPO) has been recorded.Comet assay showed a concentration dependent increase in deoxyribonucleic acid(DNA) strand breaks in Fe_2O_3-NPs treated groups.Cell cycle analysis revealed 88.4% of cells in sub-G1 apoptotic phase,suggesting cell death in Fe_2O_3-NPs(2.0 mg/m L) treated group.Taking together,the genotoxicity induced by Fe_2O_3-NPs highlights the importance of environmental risk associated with improper disposal of nanoparticles(NPs) and radish can serve as a good indicator for measuring the phytotoxicity of NPs grown in NP-polluted environment.     

纳米二氧化锰/还原态氧化石墨烯复合材料催化臭氧降解苯酚的研究

制备以还原态氧化石墨烯为载体的纳米二氧化锰催化剂,并以苯酚为目标降解物,研究了其催化臭氧化性能,对影响催化臭氧化效果因素及降解机理进行了初步探讨。使用SEM、TEM和XPS对材料进行表征;纳米二氧化锰/还原态氧化石墨烯催化臭氧降解苯酚反应为准一级反应;催化剂的最佳使用量为0.2 g/L;当p H=3时,苯酚催化臭氧化去除率相对于单独臭氧提高了119.0%;催化剂连续使用4次性能良好。     

纳米Fe_3O_4强化混凝-Fenton氧化预处理垃圾渗滤液

采用纳米Fe_3O_4与Fe Cl3制备复合混凝剂,利用混凝沉淀-Fenton氧化工艺预处理垃圾渗滤液原水,研究其处理效果。结果表明:在纳米Fe_3O_4投加量为2 g/L,Fe Cl3投加量为1.4 g/L时制备的复合混凝剂,在p H值为6.5,转速为300 r/min下快速搅拌1 min,转速为100 r/min下慢速搅拌30 min,沉淀时间为30 min的条件下,COD去除率为56.8%,ρ(COD)可由5 240 mg/L降低到2 264 mg/L;利用Fenton氧化处理混凝处理出水,在H_2O_2的投加量为5.5 g/L,n(H_2O_2)∶n(Fe2+)=4,p H值为6,反应时间为80 min,反应温度为25℃的最佳条件下,COD和氨氮的去除率分别为55.7%和40.1%,最终出水ρ(COD)和ρ(氨氮)分别为1 003 mg/L和670 mg/L;该组合工艺对垃圾渗滤液有较好的处理效果,COD、色度和氨氮的去除率分别为80.8%、59.5%和76.2%。     

中国地区氧化亚氮排放量及其变化的估算

对我国大气中氧化亚氮的排放源及其大小进行了分析和计算,中国地区氧化亚氮的年排放置为950G_9N_2O-N,约占全球总排放量的6％.天然源和人为源各占我国氧化亚氮排放量的71％和29％.在天然源中以海洋排放为主,人为源中则以煤炭燃烧释放的贡献最大.计算显示今后几年内氧化亚氮排放的年增加量是6G_9N_2O-N.     

BENEFITS FROM MANAGING FARM PRODUCED NUTRIENTS1

Manures and fertilizers are applied to agricultural lands in excess of recommended amounts, resulting in widespread pollution of surface and ground water and contributing a substantial source of greenhouse gases associated with global warming. By developing policies that exploit the value of farm produced nutrients, input costs can be minimized. Better accounting for or crediting of farm produced nutrients is leading to economically beneficial conservation of fertilizer. In addition, hog producers who own enough land may benefit from properly managing manure nutrients. Poultry litter is valuable as fertilizer and can be marketed by independent dealers to farmers in nutrient deficit areas, with very modest assistance from the government. Dairy producers may modify their past income support programs to finance central compost facilities. Although nutrient problems were neglected in the past, recent Federal initiatives and joint initiatives with states exploit many of these and other opportunities to avoid excessive application of nutrients to the land.     

WO3/TiO2复合半导体的光催化性能研究

采用Ｓｏｌ－Ｇｅｌ法制备ＷＯ３／ＴｉＯ２纳米粉末,以高压汞灯为光源,亚甲基蓝溶液的光催降为模型反应,结果表明,掺入ＷＯ３摩尔比为２％时,ＷＯ３／ＴｉＯ２的光活性最高;随着热处理温升高,ＷＯ３／ＴｉＯ光活性增强;     

广州市移动源现状及其污染控制管理对策

通过对广州市机动车辆构成状况和发展趋势、车流变化与氮氧化物变化关系以及各类车型污染排放分担率的分析,结果表明:在排放污染物的移动源中,小型车(出租车及其他小型车)和摩托车是一氧化碳、碳氢化合物的主要排放源;公共汽车等大型车是氮氧化物的主要排放源之一。并提出对广州市机动车污染控制应着重控制摩托车、小型车(特别是轿车,包括出租车)、公共汽车的污染排放。      

ZrO2负载过渡金属氧化物催化剂对CO＋NO（O2）反应的影响

本文运用固定床微反技术考察了Ｃｕ,Ｆｅ,Ｍｎ,Ｃｒ,Ｃｏ和Ｎｉ负载（ＺｒＯ２载体）氧化物对ＣＯ＋ＮＯ（Ｏ２）反应的催化活性。研究了ＮＯ和ＣＯ在不同比例时,催化剂对Ｎ２Ｏ和Ｎ２生成的影响。结果表明,在ＮＯ＋ＣＯ反应中,ＮＯ和ＣＯ的比例对催化剂活性和Ｎ２Ｏ,Ｎ２生成均有明显的影响,ＣｕＯｘ／ＺｒＯ２催化剂的活性最高;Ｎ２Ｏ是ＮＯ＋ＣＯ反应的中间产物,低温或ＮＯ过量时有利于生成Ｎ２Ｏ,高温或ＮＯ不足时有     

以堇青石蜂窝陶瓷为载体的新型钒氧化物脱氮催化剂研究

以TiO₂/Al₂O₃/堇青石蜂窝陶瓷为载体,以V₂O₅-MoO₃-WO₃为活性组分,用于氨法选择性催化还原烟气中NO的新型催化剂,并对该催化剂的活性性能和微观结构进行了评价和表征.同时,将该催化剂的活性性能与其它几种活性组分相同但载体、制备方法、结构不同的催化剂进行了对比.对比结果表明,该新型催化剂能取得最好的选择性催化还原氮氧化物催化性能BET、FT IR、XPS表征实验结果表明,其高催化活性得益于大比表面积及大孔体积,而TiO₂/Al₂O₃/堇青石蜂窝陶瓷载体及其制备方法对获得好的催化剂构型起了至关重要的作用.     

钴铜改性的ZSM-5对低浓度NO吸附性能的研究

利用固定吸附床研究了不同金属离子改性的ZSM-5分子筛对一氧化氮的吸附性能。实验发现:在过渡金属同钴离子一起改性的ZSM-5中,钴铜金属离子共同改性的ZSM-5分子筛对一氧化氮的吸附性能最好;当铜钴离子共同浸渍、铜钴离子浸渍量比(n(Cu) n(Co))为0 8和Al2O3(粘合剂)用量w(Al2O3)为23%时,改性的ZSM-5分子筛既具有良好的吸附性能又有良好的机械强度。另外,实验还发现改性分子筛吸附一氧化氮的穿透时间随吸附温度的升高而缩短,并利用热重技术,分析了吸附剂的热再生问题。