Spatio-temporal characteristics of adaptability between crop water requirements for summer maize and rainfall in Henan Province,China

Environmental Science and Pollution Research - It is very important to master the rainfall utilization efficiency and spatial-temporal distribution characteristics in order to improve the...     

Up-regulation of contractile endothelin receptors by airborne fine particulate matter in rat mesenteric arteries via activation of MAPK pathway

Fine particle matters (PM_2.5) is a well-known risk factor for cardiovascular diseases. However, the underlying molecular mechanisms are largely unknown. Vascular hyper-reactivity plays an important roles in the pathogenesis of cardiovascular diseases. The present study was designed to investigate a hypothesis that PM_2.5 up-regulated endothelin receptors in mesenteric artery and the potential underlying mechanisms. Rat mesenteric arteries were cultured with PM_2.5. The artery contractile responses were recorded by a sensitive myograph. ET_B and ET_A receptor expressions of mRNA and protein were assessed by quantitative real-time PCR, Western blotting, and immunohistochemistry, respectively. Results showed that ET_B receptor agonist, sarafotoxin 6c induced a negligible contraction in fresh artery segments, while ET_A receptor agonist, ET-1 induced an obvious contraction. After organ culture, the contraction curve mediated by ET_B and ET_A receptors were shifted toward the left. PM_2.5 1.0 μg/ml cultured for 16 h further enhanced ET_B and ET_A receptor-mediated contractile responses with a markedly increased maximal contraction. The organ culture enhanced ET_B and ET_A receptor mRNA and protein levels from fresh arteries, which were further increased by PM_2.5. The U0126 (MEK/ERK1/2 inhibitor) and SB203580 (p38 inhibitor) significantly attenuated both organ cultured-induced and PM_2.5-induced up-regulation of ET_B receptor. U0126 also suppressed organ culture-increased and PM_2.5-increased expressions of ET_A receptor. SB203580 only suppressed PM_2.5-induced enhanced expressions of ET_A receptor In conclusion, airborne PM_2.5 up-regulates ET_B and ET_A receptors of mesenteric artery via p38 MAPK and MEK/ERK1/2 MAPK pathways.

     

浙东沿海城市大气颗粒物污染特征及来源解析研究

对2009年夏季浙东沿海地区环境空气质量进行监测,监测大气颗粒物(TSP、PM10、PM2.5、PM1.0)浓度,分析颗粒物污染特征、水溶性离子及无机元素组成,运用化学质量平衡受体模型(CMB模型)对浙东沿海地区大气TSP来源进行解析.结果表明,浙东沿海地区的大气颗粒物主要以细颗粒物为主,颗粒物中主要的水溶性离子为SO2-4、NH+4、Ca2+,土壤尘是该地区大气TSP的主要来源,北仑、乐清和奉化TSP中土壤尘的分担率分别达到55.49%、42.52%、40.70%,各监测点TSP来源具有一定的地域特征.     

介质阻挡放电等离子协同TiO_2-GAC降解甲基橙的研究

采用介质阻挡放电(DBD)等离子协同颗粒活性炭负载TiO2(TiO2-GAC)对甲基橙进行降解,研究了该体系的协同处理效果,探讨了放电电压、初始pH、初始电导率、初始浓度和TiO2-GAC投加量等操作参数的影响,并建立了协同体系的表观反应动力学模型.实验结果表明,DBD与TiO2-GAC联合处理表现出明显的协同效应,处理25min后,协同体系对甲基橙的降解率和COD去除率分别为96.2%和90%,与单独DBD体系相比,分别提高了52.7%和50.4%;协同体系降解甲基橙的过程符合表观反应动力学模型,模型值与实验值吻合良好,总级数为2.352;体系中H2O2、O3浓度测定结果表明,与单独DBD体系对比,协同体系的H2O2浓度增高,而O3浓度降低,说明TiO2-GAC起到了催化作用;TiO2-GAC在DBD体系中获得了原位再生,五次再生循环后再生率达80%.     

我国典型电子废弃物拆解地农田土壤中的多溴联苯醚

选择我国主要电子垃圾拆解地清远龙塘-石角地区作为研究区,以14种多溴联苯醚(Polybrominated Diphenyl Ethers,PBDEs)化合物为研究对象,探讨了PBDEs化合物在龙塘-石角地区农田土壤中的含量、同系物组成及空间分布状况,分析了土壤TOC、土地利用方式(水旱轮作)等对农田土壤PBDEs含量特征的影响.结果表明,清远龙塘-石角地区农田土壤中14种PBDEs化合物的总量平均为(19.0±20.1)ng·g-1(以干重计),明显低于来自路边、拆解中心、居民区等表土中的PBDEs含量.研究区农田土壤中PBDEs的空间分布与土壤TOC呈现出一致性特征,当去除TOC的影响后,作为点源的电子垃圾拆解地成为土壤PBDEs分布的关键控制因素.水旱轮作的土地利用方式下,在一个轮作周期内,当轮作为水稻且土壤处于淹水状态时土壤中的PBDEs含量最低.总体来看,农田土壤中的PBDEs动态受土壤水含量、作物种植情况、土壤水旱状态等多因素的综合影响,表现出不确定的变化特征.本文的研究成果对土壤-作物系统PBDEs的行为研究进行了补充,并可为完善现有的土地质量评估体系提供基础资料.     

溴化咪唑类离子液体对胞嘧啶结构和性质影响的计算研究

离子液体被称为绿色溶剂得到广泛的应用,但离子液体并非完全无毒性,其中关于离子液体基因毒性的相关实验报道不少.本文运用密度泛函理论M06-2X和ωB97XD方法在6-311++G(2d,p)基组水平,对阳离子(C_(2/4)mim~+)、阴离子(Br~-)、离子液体([C_(2/4)mim]Br)与胞嘧啶(C)作用体系的几何结构、能量学特征、谱学性质和电子结构等进行计算研究.两种方法计算得到5种最稳定结构C-C_2mim-1、C-C_4mim-1、C-Br-1、C_21和C_41,经BSSE校正后的结合能分别为-99.1(-103.9)、-99.6(-104.3)、-102.2(-99.3)、-97.3(-100.7)和-104.5(-105.6)kJ·mol~(-1),体系中胞嘧啶变形能在2.8~6.9 kJ·mol~(-1)范围内.复合物中胞嘧啶的C2=O7和N1―H键的伸缩振动频率均发生一定程度的红移.分子中的原子理论(Atoms in molecule)得到阳离子、阴离子、离子液体与胞嘧啶作用以静电作用为主.自然键轨道分析(Natural bond orbitals)表明C_21和C_41的稳定化能主要来源于LP Br→BD~* N1—H、LP Br→BD~* N1―C2和LP O7→BD~* C2―H之间的相互作用.极化连续介质模型(Polarizable continum model)计算表明水溶液环境可削弱溴化咪唑类离子液体对胞嘧啶结构和性质的影响.