Papers by Keyword: Organic Contamination

Abstract: This study was performed to develop a fuzzy model for human health risk assessment of organic contamination of groundwater to quantify the uncertainties inherent in risk assessment processes. The fuzzy model was constructed based on the fuzzy set theory and traditional risk assessment approach. Triangular fuzzy number was used to describe the variability of parameters associated with traditional risk assessment and α-cut sets was taken to transform fuzzy numbers to intervals that can be fairly taken into arithmetic operation of lifetime cancer risk (ELCR) and hazard index (HI) which respectively denotes the carcinogenic and non-carcinogenic risks. Considering the exposure routes of drinking and showering, the developed fuzzy model yields risks at different memberships as well as the expectation of risks. The model was applied to a site in China with organics-contaminated groundwater. It was found that tetrachloroethylene (PCE) posed the most risks, followed by trichloroethylene (TCE), while carbon tetrachloride (CT) posed the smallest. Results also showed drinking, compared with showering, is the major exposure route and boiling is important for reducing health risks of groundwater.

Abstract: Methods for the analysis of the oxide-silicon interface were compared for their ability to reveal metal segregation at the interface and organic contamination. The impact of these contaminations on surface recombination velocity measurements, on capacitance vs. voltage, conductance vs. voltage and capacitance vs. time measurements and on MOS-DLTS spectra was studied. Niobium-contaminated wafers were used as an example of metal surface segregation, because it was previously shown that niobium is prone to surface segregation. Interface state density measurements obtained by the conductance method showed a limited impact of niobium implantation. Vice versa significant effects were found in MOS-DLTS spectra. For what concerns organic contamination, MOS-DLTS showed the most significant effects from the point-of-view of the intrinsic properties of the silicon oxide - silicon interface, and GOI tests demonstrate a clear impact of the organic contamination on MOS capacitors oxide breakdown events.