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991.
7B04铝合金海洋性大气腐蚀研究 总被引:5,自引:3,他引:2
通过在青岛和海南开展的7B04铝合金户外大气暴露试验,利用失重分析、形貌观察、断面分析和电化学交流阻抗谱等研究了7B04铝合金在海洋性大气环境中的腐蚀动力学规律和腐蚀特征。结果表明,在青岛和海南等海洋性大气环境中,7B04铝合金腐蚀初期以点蚀形式萌生,随后向均匀腐蚀发展;腐蚀过程均经历了腐蚀速率由高到低的过程,且腐蚀失重与时间的关系均可用幂函数显著回归;电化学阻抗谱分析表明当腐蚀产物足够厚时,7B04铝合金海洋性大气腐蚀的电化学过程由侵蚀性离子的扩散步骤来控制。 相似文献
992.
993.
Two biological aerated filters (BAF) were setup for ammonia removal treatment of the circulation water in a marine aquaculture. One
of the BAFs was bioaugmented with a heterotrophic nitrifying bacterium, Lutimonas sp. H10, where the ammonia removal was not
improved and the massive inoculation was even followed by a nitrification breakdown from day 9 to 18. The nitrification was remained
stable in control BAF operated under the same conditions. Fluorescent in situ hybridization (FISH) with rRNA-targeted probes and
cultivable method revealed that Lutimonas sp. H10 almost disappeared from the bioaugomented BAF within 3 d, and this was mainly
due to the infection of a specific phage as revealed by flask experiment, plaque assay and transmission electron observation. Analyses
of 16S rRNA gene libraries showed that bacterial groups from two reactors evolved di erently and an overgrowth of protozoa was
observed in the bioaugmented BAF. Therefore, phage infection and poor biofilm forming ability of the inoculated strain are the main
reasons for bioaugmentation failure. In addition, grazing by protozoa of the bacteria might be the reason for the nitrification breakdown
in bioaugmented BAF during day 9–18. 相似文献
994.
Accumulation of copper (Cu) and cadmium (Cd) in six rice cultivars (94D-22, 94D-54, 94D-64, Gui630, YY-1 and KY1360) was evaluated through exposure to heavy metal contamination (100 mg/kg Cu, 1.0 mg/kg Cd, and 100 mg/kg Cu + 1.0 mg/kg Cd) in a greenhouse. The dry weight of shoot and root, concentrations of Cu and Cd in plant tissues and the Cu, Cd, P, Fe concentrations in the root surface iron plaques were analyzed eight weeks later after treatment. The results indicated that the plant biomass was mainly determined by rice genotypes, not Cu and Cd content in soil. Separated treatment with Cu/Cd increased each metal level in shoot, root and iron plaques. Soil Cu enhanced Cd accumulation in tissues. In contrast, Cu concentrations in shoot and root was unaffected by soil Cd. Compared to single metal contamination, combined treatment increased Cd content by 110.6%, 77.0% and 45.2% in shoot, and by 112.7%, 51.2% and 18.4% in root for Gui630, YY-1 and KY1360, respectively. The content level of Cu or Cd in root surface iron plaques was not affected by their soil content. Cu promoted Fe accumulation in iron plaques, while Cd has no effect on P and Fe accumulation in it. The translocation of Cu and Cd from iron plaques to root and shoot was also discussed. These results might be beneficial in selecting cultivars with low heavy metal accumulation and designing strategies for soil bioremediation. 相似文献
995.
Acute toxicity of excess Cu on the photosynthetic performance of Chlorella pyrenoidosa was examined by using chlorophyll a fluorescence transients and JIP-test after exposure to elevated Cu concentrations for a short time period. High Cu concentration resulted in a significant suppression in photosynthesis and respiration. The absorption flux (ABS/RC) per PSII reaction center increased with increasing Cu concentration, but the electron transport flux (ET0/RC) decreased. Excess Cu had an insignificant effect on the trapping flux (TR0/RC). The decline in the efficiency, with which a trapped exciton can move an electron into the electron transport chain further than QA−(Ψ0), the maximal quantum yield of primary photochemistry (?P0), and the quantum yield of electron transport (?E0) were also observed. The amount of active PSII reaction centers per excited cross section (RC/CS) was also in consistency with the change of photosynthesis when cells were exposed to excess Cu concentration. JIP-test parameters had a good linear relationship with photosynthetic O2 evolution. These results suggested that the decrease of photosynthesis in exposure to excess Cu may be a result of the inactivation of PSII reaction centers and the inhibition of electron transport in the acceptor side. 相似文献
996.
取代芳烃对呆鲦鱼急性毒性的QSAR研究 总被引:4,自引:1,他引:3
应用密度泛函方法(DFT)在B3LYP/6-311G**水平上全优化计算25个取代芳烃的量子化学参数,结合疏水性参数与化合物对呆鲦鱼的急性毒性进行定量构效关系研究(QSAR)。经逐步回归筛选变量后,所建多元线性回归方程的相关系数R及去一法交互检验复相关系数R2cv分别为0.967和0.907。用预测集样本进行了外部预测,所得外部预测样本复相关系数R2ext和外部预测集交互检验Q2ext分别为0.881和0.836。模型结果显示:分子疏水性参数logP较大时具有较大的脂溶性,化合物的毒性较大;取代基的吸电子能力越强,苯环的正电性越大,化合物的毒性越大。 相似文献
997.
998.
SPME-GC/MS法测定垃圾渗沥液中双酚A 总被引:3,自引:3,他引:0
建立了固相微萃取-气相色谱质谱联用法测定垃圾渗沥液中双酚A的方法,并用于广州大田山垃圾渗沥液中双酚A含量的测定。对影响萃取的参数进行了优化,实验选用涂层厚度为85μm聚丙烯酸酯(PA)萃取纤维,在搅拌速度为1200r/min、NaCl浓度为20%、pH2.0和室温条件下萃取60min。方法的线性范围为0.1~100μg/L,检出限为0.03μg/L,精密度为6.6%。应用本方法监测了广州大田山垃圾渗沥液中BPA的含量在生物法处理过程中的变化情况。 相似文献
999.
1000.