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Lead (Pb) and copper (Cu) contamination seriously threatens agricultural production and food safety. This study aims to investigate Pb and Cu induced hormetic effect and toxicity mechanisms in lettuce (Lactuca sativa L.) and establish reliable empirical models of potentially toxic elements (PTEs) transfer in the soil-plant system. The content and distribution of Pb and Cu at subcellular levels in lettuce plants were examined using inductively coupled plasma-mass spectrometry, differential centrifugation and micro-X-ray fluorescence spectroscopy. The PTE-loaded capacity of Pb that ensures food safety was lower than that of Cu in the studied soil, but the PTEloaded capacity of Pb that limits yield was higher than that of Cu. Lead in lettuce roots mainly accumulated in the cell wall (41%), while Cu mainly accumulated in the vacuoles (46%). The Pb and Cu were primarily distributed in the radicle of lettuce seeds under severe PTE stress, resulting in no seed development. Iron plaque formed on the root surface of lettuce seedlings and sequestered Pb and Cu via chelation. At the same concentration, lettuce was less tolerant to Cu in contaminated soil than Pb due to the higher activity of Cu ions in the soil. Lead was more phytotoxic to lettuce than Cu, however, since the radicle emerged from the seed under severe Cu levels, while it did not protrude under severe Pb levels. The potentially damaging effect of Pb in the visually healthy lettuce appeared to be higher than that of Cu under the same soil contamination level.

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The feasibility of monitoring changes in guided waves' characteristics in a fractured long bone as modeled by a hollow cylinder and a callus at different healing stages is studied. Various guided wave modes are detected and extracted from a broadband signal at several discrete locations. The energy-spectrum and v(FEP) (effective velocity of the first energy peak in callus region) of guided modes are found sensitive to the healing process in different aspects and stages. The healing process may be divided into several sub-courses, each of which can be evaluated by different combinations of guided wave modes. The energy-spectrum indicates that the longitudinal tube modes L(0,1) and L(0,2) are suitable for early healing; L(0,1), L(0,2), L(0,3), and L(0,5) for midway-course; and L(0,1) and L(0,3) for late consolidation, while L(0,2), L(0,5), and L(0,8) are suitable for detecting the change in callus geometrics. The v(FEP) results suggest that L(0,5) for monitoring early-course; L(0,3) and L(0,7) for midway process; L(0,2) for later consolidation, and L(0,7) for monitoring geometrical variation.

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The characteristics and function of geographic information system (GIS) technique were summarized and the advantages of GIS application in environmental impact assessment (EIA) were introduced. GIS can provide good function of information technology for EIA, based on its strong ability on processing spatial data and attribute data. The applications of GIS in establishing environmental information database, selecting sites for projects, making environmental thematic map and combining with environmental model to predict environmental impact were introduced. The traffic noise prediction of Beijing Xiwai Street west extension project in EIA report was taken as an example to introduce GIS application in urban road EIA.