植物铜素毒害及其抗性机制研究进展

Cu是植物生命活动必需的微量矿质元素，广泛参与各种生命活动；但过量Cu胁迫将诱导植物细胞产生大量活性氧，引起膜脂过氧化，膜透性增大，细胞内容物大量外渗，甚至发生细胞死亡。Cu^2 扩散到细胞核内会诱发DNA之间、蛋白质之间以及DNA和蛋白质之间发生分子内和分子间交联，DNA链的断裂、重排和脱嘌呤作用等前诱变损伤以及DNA期外合成、DNA甲基化异常等遗传毒害。植物细胞在长期进化过程中形成了各种抗Cu素毒害机制，如细胞壁的固着作用、质膜的限制作用、有机小分子(有机酸、植物螯合肽、金属硫蛋白)螯合作用等。文章综述了有关研究的最新进展。     

重大突发事件下应急冷链供应链协同化评价模型及策略研究*

为有效规避冷链供应链受突发事件带来的不利影响,并强化其应急体系协同化发展,提出基于层次分析法和序参量法的应急冷链供应链协同化水平评价模型。模型以供应链协同化理论为基础,从协同化目标入手构建影响其协同化水平的测度指标体系;利用层次分析法确定评价指标的综合权重,最后运用序参量法评估冷链供应链各应急环节的协同度。结果表明:评价模型能有效评估应急冷链供应链协同化水平,可为冷链供应链应对突发事件提供参考。     

Explosion regions and limiting oxygen concentrations of methyl propionate,methyl acetate,dimethyl carbonate with air and inert gas mixtures

New data about explosion regions with special focus on limiting oxygen concentrations for methyl propionate, methyl acetate, dimethyl carbonate with air in the presence of nitrogen, helium and carbon dioxide were determined at ambient initial pressure and 423 K. The measurements were executed according to EN 1839 method T. The changes of the explosion regions with temperature and type of inert gas were also modeled mathematically using an extended calculated adiabatic flame temperature profile (CAFTP) method. The shift of the explosion region boundaries with temperature when switching from nitrogen to carbon dioxide were reproduced well. For a switch to helium a good agreement could be reached only if the very high thermal conductivity of helium had been considered properly by using the Lewis number. This requires the knowledge of the respective Lennard-Jones parameters. The LOC of helium-containing mixtures can, however, be calculated with acceptable accuracy even if the Lennard-Jones parameters of the flammable substance are not known exactly by using reasonable estimations.     

Experimental study of nitrite accumulation in predenitrification biological nitrogen removal process

The effect of dissolved oxygen (DO) concentration on nitrite accumulation was investigated in a pilot-scale pre-denitrification process at room temperature for 100 days. In the first 10 days, due to the instability of the system, the DO concentration fluctuated between 1.0 and 2.0 mg/L. In the next 14 days, the DO concentration was kept at 0.5 mg/L and nitrite accumulation occurred, with the average nitrite accumulation rate at 91%. From the 25th day, the DO concentration was increased to 2.0 mg/L to destroy the nitrite accumulation, but nitrite accumulation rate was still as high as 90%. From the 38th day the nitrite accumulation rate decreased to 15%–30% linearly. From the 50th day, DO concentration was decreased to 0.5 mg/L to resume nitrite accumulation. Until the 83rd day the nitrite accumulation rate began to increase to 80%. Dissolved oxygen was the main cause of nitrite accumulation, taking into account other factors such as pH, free ammonia concentration, temperature, and sludge retention time. Because of the different affinity for oxygen between nitrite oxidizing bacteria and ammonia oxidizing bacteria when DO concentration was kept at 0.5 mg/L, nitrite accumulation occurred. __________ Translated from Environmental Science, 2006, 27(12): 2472–2476 [译自: 环境科学]     

满江红花青素在镉胁迫下的抗氧化作用

为了研究镉胁迫诱导满江红体内花青素合成的生理功能,采用镉诱导和体外实验的方法评价了满江红体内花青素的抗氧化作用.测试指标包括还原力、清除超氧阴离子(O-2)、过氧化氢(H2O2)、羟自由基(·OH)的能力.结果表明,花青素的还原力和对氧自由基的清除作用随花青素提取物浓度的增加而增加.因此,镉胁迫下合成的花青素是一种清除活性氧自由基的良好抗氧化剂.镉胁迫对满江红活性氧代谢影响的试验结果表明,在0.5mg·L-1Cd胁迫下,满江红体内O-2和H2O2大量积累,造成活性氧胁迫,说明花青素只能在一定程度上保护满江红免受过氧化伤害.本实验初步证实,花青素含量的增加是满江红抗性机理之一,可缓解镉的毒害.     

Effects of COD/N ratio and DO concentration on simultaneous nitrification and denitrification in an airlift internal circulation membrane bioreactor

The effects of chemical oxygen demand and nitrogen(COD/N)ratio and dissolved oxygen concentration(DO)on simultaneous nitrification and denitrification(SND)were investigated using an airlift internal circulation membrane bioreactor(AIC-MBR)with synthetic wastewater.The results showed that the COD efficiencies were consistently greater than 90% regardless of changes in the COD/N ratio.At the COD/N ratio of 4.77 and 10.04,the system nitrogen removal efficiency became higher than 70%.However,the nitrogen rem...     

饮用水源地重金属溶出的影响研究——以广东石门台水库为例

文章研究对饮用水源地水水质现状进行了全面调查;采集水源地土壤进行浸泡释放实验和模拟酸雨的淋溶实验,结果表明在充分搅拌释放条件下,释放污染物对于水质影响不大;而淋溶实验表明各元素释放强度依次为:Mn>Ni>Cu>Pb>As>Hg;Mn和Ni的淋出液浓度超过了地表水水源地水质标准;pH为3.0和5.6的酸雨对于硫铁矿区重金属的溶出和迁移均是有利条件,pH为5.6的酸雨对于钨矿区重金属的溶出更为有利。     

城市饮用水源地水质健康风险评价

介绍饮用水水源受到基因毒物质和躯体毒物质所致的健康危害的风险度计算模型,并应用于西安市饮用水源地饮水途径健康风险评价,分别计算出了各类污染物的风险度。结果表明：（1）基因毒物质镉所致健康风险大约为10^-7a^-1,躯体毒物质所致风险在10^-12～10^-10之间。所以,基因毒物质是首先控制的污染物质。（2）对于躯体毒物质,铅的风险度是最高的,躯体毒物质所致的风险度大小排序为Pb〉NH3-N〉Hg〉挥发酚。（3）饮用水中的所有有害物质的健康危害总风险度未超过国际辐射防护委员会（ICRP）推荐的最大可接受限值5.0×10^-5a^-1,也没超过瑞典环保局、荷兰建设和环境部推荐的最大可接受水平6.0×10^-5a^-1。研究结果可直接确定该市地表水源水质的风险污染物的主次及治理的优先顺序,为该市地表水源水质风险管理提供了帮助。     

HIPS阻燃复合材料三元潜在火灾危险性评价

将高抗冲聚苯乙烯树脂颗粒(纳米/微米级)、十溴二苯乙烷颗粒、三氧化二锑、弹性体、分散剂和偶联剂通过一步熔融共混工艺先行制备UL94 V-0级阻燃母粒,再将其与HIPS本体树脂按不同比例混合制得阻燃复合材料,并利用极限氧指数(LOI)、垂直燃烧(UL94)及ISO 5660锥形量热计三项测试表征制得样品的燃烧和火灾性能,从中提炼和分析LOI、垂直燃烧等级和最大热释放速率(Pk HRR)等三元关键指标相关性,给出了定性定量相结合的潜在火灾危险性分级范围。结果表明:UL94燃烧等级和Pk HRR相关性体现为当Pk HRR≤330.0 k W/m~2时,试样UL94等级均为V-0级;UL94燃烧等级和LOI相关性体现为随UL94燃烧等级从V-0降到HB时,试样LOI从27.0降到17.0;Pk HRR与LOI相关性体现为Pk HRR与LOI呈粗略反向线性相关性;UL94燃烧等级、Pk HRR和LOI三元相关性体现为当LOI22.0、Pk HRR为399.0~665.0 k W/m~2时,材料UL94燃烧等级介于HB~V-2。     

蓝藻胞外聚合物对供水管网水质的影响

针对游离态蓝藻胞外聚合物（EPS）在常规水处理工艺中不易去除、残留蓝藻EPS极易进入供水管网的特性,研究了蓝藻EPS对供水管网水质变化及生物稳定性的影响.针对管道使用时限分析了不同管道内部产生附膜条件下,蓝藻EPS对供水管网中余氯、浑浊度、生物稳定性、有机组分等主要水质指标变化规律的影响.结果表明,蓝藻EPS加快了管网余氯衰减速度,导致管网水质浑浊度在12~24h后即超出生活饮用水卫生标准上限,并使管网水质生物稳定性降低,BDOC在72h内增加37.2~39.5%,AOC增加365~393%,总活菌数升高18~20倍.阐明了蓝藻水华爆发时期净水厂出厂水残留蓝藻EPS在管网余氯存在前提下,仍然能够作为微生物营养基质和代谢能量,而促进管道内细菌生长繁殖,增加微生物代谢活性,刺激微生物胞外有机组分分泌释放,导致管网水质二次污染.