遥感震害快速定量评估方法及其在玉树地震中的应用

在伽师地震、汶川地震遥感定量化灾害评估基础上,提出了基于少量现场调查样本进行遥感解译震害与地面实际震害定量评估的方法,以玉树地震为例,建立了遥感解译震害与现场调查结果的定量关系,并进一步得到了玉树县城结古镇街区的等效震害指数和结古镇综合震害指数,结果显示遥感震害快速定量评估结果与实际调查结果一致.该模型可应用于建筑物结构类型分布与玉树县结古镇相似的城镇遥感震害评估工作中.     

应急避难场所的规划建设——基于玉树地震调查数据的研究

对玉树地震灾区的应急避难情况进行了实际考察和问卷调查,基于所获取的数据分析了应急避难及紧急疏散中存在的问题,在总结多次地震灾区经验教训和国内外部分城市应急避难场所建设经验的基础上,对应急避难场所的功能设计及运营管理提出了建议。     

Use of sensitive methods for detection of DNA damage on human lymphocytes exposed to p,p′-DDT: Comet assay and new criteria for scoring micronucleus test

Wide distribution, stability and long persistence in the environment of dichlorodiphenyltrichloroethane (DDT), probably the best-known and most useful insecticide in the world, imposes the need for further examination of the effect of this chemical on human health and especially on the human genome. In this study, peripheral blood human lymphocytes from a healthy donor were exposed to 0.025 mg/L concentration of p,p′-DDT at different time periods (1, 2, 24 and 48 h). For the assessment of genotoxic effect, the new criteria for scoring micronucleus test and alkaline comet assay were used. Both methods showed that p,p′-DDT induces DNA damage in low concentration used in this research. Results of micronucleus test showed a statistically significant (p < 0.05) genotoxic effect of p,p′-DDT on human lymphocytes compared with corresponding control and a different exposure time. A comet assay also showed increased DNA damage caused in p,p′-DDT-exposed human lymphocytes than in corresponding control cells for the tail length. Results obtained by measuring the level of DNA migration and incidence of micronuclei (MN), nucleoplasmic bridges (NPBs) and nuclear buds (NBUDs) indicate the sensitivity of these tests and their application in detection of primary genome damage after long-term exposure to establish the effect of p,p′-DDT on human genome.     

Determination of hypoxia and dietary copper mediated sub-lethal toxicity in carp, Cyprinus carpio, at different levels of biological organisation

Hypoxic events frequently occur in the aquatic environment in association with micro pollutants, including heavy metals. Only a few studies are however available on the uptake and biological responses of heavy metals under hypoxic conditions. To elucidate the phenomenon, mirror carp Cyprinus carpio L. (16.13-16.22 g) were exposed chronically to dietary copper (Cu; 250 and 500 mg kg dry wt.⁻¹) for 30 d under normoxic (8.25 mg O₂ L⁻¹) and hypoxic (∼3 mg O₂ L⁻¹) conditions and adopting an integrated approach, sub-lethal biomarker responses were determined at different levels of biological organisation. Level of oxidative DNA damage (as determined by modified Comet assay) showed strong significant difference following exposure to dietary Cu level under normoxic (1.6-fold) as well as under hypoxic condition at both Cu levels (2.1 and 2.5-folds respectively). Significant difference was also observed for haematological parameters (i.e. increased red and white blood cells, haematocrit value and haemoglobin concentration). Quantitative histology revealed alterations in tissues (i.e. liver and gills) for hypoxic and all dietary Cu treatment groups under both normoxic and hypoxic conditions suggesting a compensatory response to these organs (p < 0.05). The order of Cu accumulation in tissues (as determined by ICP-OES) was liver > intestine > kidney > gill. Interestingly, SGR under both normoxic and hypoxic conditions reduced with elevating Cu levels (p = 0.019). Overall, the results provide evidence for enhanced toxicological responses in fish following exposure to Cu either alone or in combination with hypoxic condition and lends support to the evolving viewpoint that many water quality guidelines should be revisited in terms of new ecotoxicological criteria.     

Can Hediste diversicolor (Nereidae, Polychaete) be considered a good candidate in evaluating PAH contamination? A multimarker approach

The aim of this study was to develop a preliminary characterization of the biological responses of Hediste diversicolor to polycyclic aromatic hydrocarbons (PAHs) under controlled laboratory conditions. In order to test the effects of PAH exposure, a battery of biomarkers was applied to the polychaetes by exposing them to sublethal concentrations of benzo[a]pyrene (0.1 and 0.5 mg L⁻¹) for 10 d under laboratory conditions. The battery of biomarkers tested included oxidative stress biomarkers (glutathione content, enzymatic activities of catalase, glutathione S-transferases, glutathione reductase, glutathione peroxidases), total oxyradical scavenging capacity (TOSC) toward peroxyl and hydroxyl radicals and activity of acyl CoA oxidase (AOX) as a marker of peroxisome proliferation measured in the entire body; lipofuscin and neutral lipid accumulations and levels of Ca²⁺-ATPase activity analyzed in the intestinal epithelium; lysosomal membrane stability and genotoxic effects measured as DNA strand breaks and frequency of micronuclei in coelomocytes. Chemical analyses were also carried out to verify the polychaete’s benzo[a]pyrene (B[a]P) bioaccumulation levels after the exposure period. The results obtained indicate that B[a]P caused significant changes in most of the parameters measured in H. diversicolor. Biological responses to the organic compound were particularly significant for the biomarkers measured in the intestinal epithelium and in coelomocytes, emphasizing that these tissues were more affected during our experimental conditions. Considering the key trophic role of this benthic species in estuarine and coastal ecosystems, this study confirmed that H. diversicolor is an appropriate bioindicator of organic contamination.     

Cadmium-induced DNA damage and mutations in Arabidopsis plantlet shoots identified by DNA fingerprinting

Random amplified polymorphic DNA (RAPD) test is a feasible method to evaluate the toxicity of environmental pollutants on vegetal organisms. Herein, Arabidopsis thaliana (Arabidopsis) plantlets following Cadmium (Cd) treatment for 26 d were screened for DNA genetic alterations by DNA fingerprinting. Four primers amplified 20-23 mutated RAPD fragments in 0.125-3.0 mg L⁻¹ Cd-treated Arabidopsis plantlets, respectively. Cloning and sequencing analysis of eight randomly selected mutated fragments revealed 99-100% homology with the genes of VARICOSE-Related, SLEEPY1 F-box, 40S ribosomal protein S3, phosphoglucomutase, and noncoding regions in Arabidopsis genome correspondingly. The results show the ability of RAPD analysis to detect significant genetic alterations in Cd-exposed seedlings. Although the exact functional importance of the other mutated bands is unknown, the presence of mutated loci in Cd-treated seedlings, prior to the onset of significant physiological effects, suggests that these altered loci are the early events in Cd-treated Arabidopsis seedlings and would greatly improve environmental risk assessment.     

Coupled hydromechanical modeling of CO2 sequestration in deep saline aquifers

Sequestration of carbon dioxide (CO₂) in deep saline aquifers has emerged as an option for reducing greenhouse gas emissions to the atmosphere. The large amounts of supercritical CO₂ that need to be injected into deep saline aquifers may cause large fluid pressure increases. The resulting overpressure may promote reactivation of sealed fractures or the creation of new ones in the caprock seal. This could lead to escape routes for CO₂. In order to assess the probability of such an event, we model an axisymmetric horizontal aquifer–caprock system, including hydromechanical coupling. We study the failure mechanisms, using a viscoplastic approach. Simulations illustrate that, depending on boundary conditions, the least favorable moment takes place at the beginning of injection. Initially, fluid pressure rises sharply because of a reduction in permeability due to desaturation. Once CO₂ fills the pores in the vicinity of the injection well and a capillary fringe is fully developed, the less viscous CO₂ displaces the brine and the capillary fringe laterally. The overpressure caused by the permeability reduction within the capillary fringe due to desaturation decreases with distance from the injection well. This results in a drop in fluid pressure buildup with time, which leads to a safer situation. Nevertheless, in the presence of low-permeability boundaries, fluid pressure continues to rise in the whole aquifer. This occurs when the radius of influence of the injection reaches the outer boundary. Thus, caprock integrity might be compromised in the long term.     

Ozone tolerance in Phaseolus vulgaris depends on more than one mechanism

Two bean cultivars with different sensitivity to ozone, i.e. the O₃-sensitive Cannellino and the O₃-tolerant Top Crop, were exposed to acute O₃-stress (165 nL L⁻¹) with the aim of evaluating physiological and biochemical traits that may confer O₃-tolerance. Stomatal conductance was smaller and the ability to dissipate excess energy, via regulated and unregulated nonphotochemical quenching mechanisms was greater in Top Crop than in Cannellino. These morphological and physiological-traits allowed the O₃-tolerant cultivar to compensate for the light-induced declines in Φ_PSII, to preserve photosystem II from excitation-energy, and likely to prevent the generation of ROS to a superior degree than the O₃-sensitive cultivar. Furthermore, the potential capacities to reducing the superoxide anion and H₂O₂ were significantly greater in Top Crop than in Cannellino. These findings are consistent with the early accumulation of H₂O₂, the almost complete disruption of cell structure, and irreversible damages to the photosynthetic apparatus observed in the O₃-sensitive cultivar.     

粘滞阻尼支撑框架结构弹塑性时程分析

对阻尼支撑框架结构的弹塑性时程分析方法进行了探讨,给出了阻尼支撑的力学计算模型;对地震动的选用进行了分析,给出了地震动选取的初步建议。建立了两个三层的单榀粘滞阻尼支撑框架结构,利用IDARC 2D非线性分析软件进行了弹塑性时程分析,对框架弹塑性阶段的地震响应、塑性铰分布及结构损伤进行了对比研究,提出了阻尼支撑框架结构的设计要点,为实际工程提供设计依据。     

基于结构多尺度分析的超大跨斜拉桥损伤定位方法研究

以苏通大桥斜拉桥的扁平钢箱梁结构为分析对象,采用子结构方法,将扁平钢箱梁结构的整体尺度动力特性和细节尺度构件损伤相互衔接,实现了超大跨斜拉桥的多尺度损伤分析。在此基础上,对模态曲率指标和模态应变能指标的损伤识别效果进行了对比分析。结果表明:采用子结构方法可以有效地实现钢箱梁局部构件损伤与整体结构响应的多尺度衔接,从而较真实地研究钢箱梁局部构件损伤对超大跨斜拉桥动力特性的影响;无噪声情况下,模态曲率指标能正确识别所有损伤工况,而模态应变能指标则对部分损伤工况的识别效果较差;模态应变能指标的抗噪声能力总体上优于模态曲率指标。