DBP对铜绿微囊藻生长和抗氧化酶的影响

文章研究不同浓度邻苯二甲酸二丁酯对铜绿微囊藻生长、叶绿素a含量、藻液中可溶性磷含量、超氧化物歧化酶(superoxide dismutase,SOD)和过氧化氢酶(catalase,CAT)活性的影响。结果表明:和对照组相比,DBP在较低浓度范围内(1~4 mg/L)促进铜绿微囊藻的生长特性、SOD和CAT的活性;然而较高浓度的DBP(8 mg/L)却对藻类的生长表现出抑制作用,同时还会降低SOD、CAT的活性。这表明:随着浓度的增加,DBP对铜绿微囊藻生长的影响呈现先促进,后抑制的效果。研究结果可为水华化感抑制剂的研发和安全使用提供理论指导作用,同时对全面了解水华暴发机制有一定的意义。     

溶解氧对好氧/延长闲置SBR除磷性能的影响

以合成废水为研究对象,乙酸钠为外加碳源,考察不同溶解氧(DO)浓度下好氧/延长闲置(O/EI)序批式反应器的除磷效果,并通过分析典型周期内磷元素及微生物体内各储能物质的变化,探究DO浓度对O/EI工艺除磷性能的影响机制.结果表明,低DO浓度(1 mg·L-1)条件下,O/EI系统具有良好的除磷效果,除磷率高达96%,单位污泥除磷量为5.02 mg·g-1;而当DO浓度较高(4 mg·L-1)时,反应器内磷的去除率降至50%,单位污泥除磷量仅2.81 mg·g-1.研究表明,在DO浓度为1 mg·L-1时,微生物能合成较多聚羟基脂肪酸酯(PHAs),糖原的合成及利用较少,系统好氧吸磷量远高于其他反应器,并在闲置期释放出更多聚磷酸盐.可见,DO可通过影响微生物体内PHAs和糖原的合成及转化,闲置期释磷,好氧前期释磷及好氧吸磷,进而影响系统的除磷性能.     

邻苯二甲酸二异壬酯致小鼠肾组织氧化损伤的研究

邻苯二甲酸二异壬酯是一种新型替代增塑剂,对其毒性研究已受到广泛关注。为探究邻苯二甲酸二异壬酯对肾组织的氧化损伤作用,将昆明小鼠随机分为5组,包括1个阴性对照组、4个邻苯二甲酸二异壬酯染毒组,按0.5、5、50和500 mg·kg-1四个剂量水平灌胃染毒14天。制备小鼠肾组织切片进行病理学观察,以肾组织匀浆测定活性氧(reactive oxygen species,ROS)、还原型谷胱甘肽(glutathione,GSH)、丙二醛(malondialdehyde,MDA)和8-羟基脱氧鸟苷(8-hydroxy-2-deoxyguanosine,8-OHd G)的含量,以肾组织细胞悬液测定DNA-蛋白质交联(DNA-protein Crosslink,DPC)系数。随着邻苯二甲酸二异壬酯染毒剂量的升高,小鼠肾组织的损伤程度加重,ROS、MDA、8-OHd G含量和DPC系数逐渐上升,GSH含量逐渐降低,各指标均呈一定剂量-效应关系。染毒剂量为5 mg·kg-1时,ROS、DPC系数差异有统计学意义(P0.05,P0.01);染毒剂量为50 mg·kg-1和500 mg·kg-1时,ROS、GSH、8-OHd G、MDA含量和DPC系数差异均有统计学意义(P0.05,P0.01)。结果表明较高剂量(≥50 mg·kg-1)邻苯二甲酸二异壬酯可造成小鼠肾组织氧化损伤。     

拟除虫菊酯气相色谱手性拆分方法及其影响因素分析

拟除虫菊酯具有较强的手性特征,包含多种异构体,不同异构体具有不同的生物活性,因此,其异构体的手性拆分具有重要的意义。气相色谱分析法因其分辨率高,峰容量大,灵敏度高、分析时间短,选择性强等特点,已被广泛应用于拟除虫菊酯的手性拆分中。文章通过阐述基于氢键作用、配位作用、包结络合作用的3种手性固定相的拆分机制,综述了气相色谱用于拟除虫菊酯手性分离的研究状况。此外,文章还分析了有机溶剂、水、温度等对拟除虫菊酯在拆分过程中差向异构现象的影响。     

方钢管再生混凝土柱恢复力模型试验与分析北大核心CSCD

为研究低周反复荷载作用下方钢管再生混凝土柱的恢复力模型,以再生粗骨料取代率和轴压比为变化参数,设计并制作了6个试件,进行拟静力试验。观察试件的破坏形态,实测试件的滞回曲线,综合采用定点指向、位移幅值承载力突降、模型软化点等特殊处理方法,建立以相对屈服点、相对峰值点和相对破坏点为特征点并结合滞回曲线和卸载刚度的三折线荷载—位移恢复力模型。结果表明:试件破坏形态与普通钢管混凝土柱相似,方钢管底部鼓曲破坏,再生混凝土底部被压碎。试件的滞回曲线比较饱满,且稳定性良好。建立的低周反复荷载作用下方钢管再生混凝土构件的三折线恢复力模型与实测滞回曲线吻合较好,建议用于该类新型组合结构的弹塑性地震反应分析。     

Separation of chlorinated hydrocarbons and organophosphorus, pyrethroid pesticides by silicagel fractionation chromatography and their simultaneous determination by GC-MS

A silicagel fractionation procedure for environmental sample extracts, which separates chlorinated hydrocarbons(CHCs) and organophosphorus, pyrethroid pesticides into two groups for subsequent instrumental analysis, was developed in this study. This method was achieved by optimizing the fraction cut-off volume of elution and different solvents. Using fully activated silica gel and cut-off CHCs collection after 10ml 10% dichloromethane (DCM) in n-hexane passing through the column resulted in satisfactory separation of CHCs and organophosphorus, pyrethroid pesticides. This procedure had a higher reliability for CHCs than for organophosphorus, pyrethroid pesticides, because there is a relatively reliable recovery for CHCs. This approach is less expensive due to reducing sample pre-treatment time and solvent consumption.     

Organochlorines in sediments and mussels collected from coastal sites along the Pearl River Delta, South China

IntroductionContaminationofthemarineenvironmentassociatedwithorganochlorineshasreceivedincreasingattentionoverthelastthirtyyears.Particularattentionhasbeenfocusedonthecoastalzoneandestuaries ,especiallynearmetropolitanregion(Sericano ,1990 ) .ThePearlRiverestuarine ,rangefromDayaBayintheeasttoChangshanIslandsinthewest,supportslargepopulationsofmarineorganismsandextensivefisheriesintheSouthChina .Sincethe 1980s ,therehasbeenrapideconomicdevelopmentinthePearlRiverDeltaresultinginexcessivedi…     

Photochemistry of insecticide imidacloprid: direct and sensitized photolysis in aqueous medium

The direct and sensitized photodegradations of imidacloprid, 1-(6-chloro-3-pyridinylmethyl)-N-nitro-2-imidazolidinimine, were investigated in aqueous solution and with and without various photo-sensitizers. Results of the study revealed that the intensity of lamp-house and irradiation wavelength had significant effects on the photolysis of imidacloprid. Complete degradation of 20 mg/L imidacloprid in aqueous phase was observed in 40 min under ultraviolet(UV) irradiation system, suggesting the ultraviolet ray played significant role in direct photolysis of imidacloprid. The additions of various photo-sensitizers lead to improve the degradation efficiency of imidacloprid under the irradiation of black light fluorescent lamp. TiO2 was the most efficient in the photo-catalytic degradation of imidacloprid among other photo-sensitizers in used this study. However, addition of acetone inhibited the photolysis of imidacloprid under the irradiation of UV, indicating the occurrence of competition between acetone and imidacloprid for photos. Mineralization of the imidacloprid was examined to clarify the final photochemical degradation products of the insecticide which were CO2, CI^- and NO3^-. Complete photo-oxidation of nitrogen to NO3^- occurred very slowlyvia the intermediate formation of NH4^ and NO2^- .     

拟动力试验方法的发展与展望

结构抗震试验是模拟地震作用、分析掌握地震机制及结构抗震性能的有效方法。对拟动力试验技术的研究现状和进展进行了概括总结,分析探讨了拟动力试验特别是基于子结构技术试验的逐步积分方法、加载控制方式、误差分析、拟动力子结构试验、实时子结构试验、远程协同拟动力试验、混合子结构拟动力试验等关键技术,对比分析了拟动力试验技术与其他试验方法的差异,以及拟动力试验技术中基于子结构技术各试验方法间的区别和特点,并进一步阐述了各种拟动力试验的现存问题、应用前景,指出了需要进一步研究的方向。     

双(对羧苯基)苯基氧化膦阻燃改性聚酯的热解和燃烧特性实验研究

本文以双(对羧苯基)苯基氧化膦为阻燃单体,合成了阻燃共聚酯(COPET)。通过热失重分析和锥形量热分析,研究了阻燃共聚酯的热降解行为和燃烧特性,并对阻燃剂的阻燃机理进行了简单的讨论。实验结果表明,阻燃剂双(对羧苯基)苯基氧化膦是适于聚酯的较好阻燃剂,但其发烟量有待抑制。