Impact of contamination

Optics contamination, in EUV Lithography, V. Bakshi, Ed., pp. 227 259, SPIE Press, Bellingham, WA (2009). 

Hollenshead and L. Klehanoff, Modeling extreme ultraviolet/H20 oxidation of ruthenium optic coatings, J. Vac. Sci. Technol. B 24,118 130 (2006) Y. Gomei, H. Takase, T. Aoki, Y. Kakutani, and M. Niihe, Scaling law in acceleration test of extreme ultraviolet lithography projection optics mirror contamination, J. Vac. Sci. Technol. B 23, 2848 2851 (2005) A.N. Broers, W.W. Molzen, J.J. Cuomo, N.D. Wittels, Electron beam fabrication of 80A metal structures, Appl. Phys. Lett. 29, 596 598 (1976). 

Hollenshead and L. Klehanoff, Modeling radiation induced carbon contamination of extreme ultraviolet optics, J. Vac. Sci. Technol. B 24, 64 82 (2006). 

Second, because contamination resulting from carbon deposition depends on the local intensity of the EUV radiation at the surface of the mirror, it is possible that certain parts of the mirror surface in the projection optics may experience a local reduction in reflectivity that is larger than that occurring at other locations. The result is apodization of the projection optics, which can cause CD variation across the chip that is printed with EUV lithography.  

La Fontaine, EUV optics, in Extreme Ultraviolet Lithography, B. Wu and A. Kumar, Eds., Chapter 4, McGraw Hill, New York (2009). 

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Retention and drainage additives are vital to the use of recycled fibers. Papermakers consider recycled fibers to behave like virgin fines, while recycled fines behave like filler. Drainage on the paper machine can be impeded and first-pass retention reduced by the use of recycled fiber (9). Additionally, the negative impact of contaminants found in recycled fibers can be minimized by the appropriate use of dispersants and other pitch-control additives. 

Steam Sampling Awareness. The very common problem of lack of any reliable sample points in the steam condensate system presumably exists on the premise that somehow the smaller the boiler, the less the risk of condensate-related problems or the lower the potential impact of contamination. Unfortunately, this premise is simply not true as some operators can testify when the repair bills arrive or... 

Potential impacts of contaminants on habitat are reductions in cover and quality. The loss of preferred habitat may leave animals more susceptible to predation and disease. Loss of reproductive habitat may result in fewer animals reproducing in a given season or exposing the young to increased predation. For some animal populations, then, habitat changes may lead to decreased reproduction, increased mortality, and increased emigration. 

Assessments of the quality status of water systems are required as part of the WFD. These assessments include data on the concentrations of contaminants in different compartments such as water and sediment. It is, however, perhaps more important is to assess the impact these contaminants may have on the ecosystem and to predict future impacts. The impact of contaminants is determined by the behaviour of chemicals in the system, determining exposure of biota and the... 

The impacts of contaminants on the structure of the immune system can be assessed by examining white blood cell (WBC) numbers and the mass and cellularity of immune organs, although these indicators are usually not as sensitive as measures of immune function. Avian immunotoxicity studies frequently assess total and (or) differential WBC counts [79], and immunosuppression can be indicated by reduced numbers of WBCs or elevated WBC numbers caused by recurrent infections. An elevated heterophil to lymphocyte ratio can indicate altered immune status in response to corticosteroid stress hormones or other factors [78,7 9], Exposure to lead shot or lead acetate has been shown to alter total and (or) differential WBC numbers in Japanese quail (Coturnix coturnix) and mallards [81-83], In western grebes (Aechmophorus occidentalis) from California, concentrations of mercury in the kidney were positively correlated with heterophil... 

Richardson, J.S., Hall, K.J., Kiffiiey, P.M., Smith, J.A. and Keen, P. (1998) Ecological impacts of contaminants in an urban watershed, DOE FRAP 1998-25, Environment Canada, Environmental Conservation Branch, Aquatic and Atmospheric Sciences Division, Vancouver, BC, 22 pp. 

Contaminated sites may pose risks to both the environment and human health. The impacts of contaminated sites in the UK and internationally are managed using a conceptual risk-based assessment model ... 

New awareness of the potential danger to water supplies posed by the use of agricultural chemicals and urban industrial development has also focused attention on the nature of rainfall-runoff and recharge processes and the mobility of various solutes, especially nitrate and pesticides, in shallow systems. Dumping and spills of other potentially toxic materials are also of concern because these chemicals may evenmally reach streams and other public water supplies. A better understanding of hydrologic flow paths and solute sources is required to determine the potential impact of contaminants on water supplies, develop management practices to preserve water quality, and devise remediation plans for sites that are already polluted. 

Within the petroleum industry, emulsion of oil and water may be associated with every stage of production, transportation, or refining. The extent of emulsification and the economic impact of contaminants associated with emulsions in hydrocarbon-processing equipment will determine what treating methods, if any, are necessary to produce desired hydrocarbon specifications. An understanding of the impact of oil contaminants and incomplete demulsification on key hydrocarbon processing areas is required. The prime areas of concern are typically... 

Whitehead A, Anderson SL, Kuivila KM, Roach JL, and May BP (2003) Genetic variation among interconnected populations of Catostomus occidentalis Implications for distinguishing impacts of contaminants from biogeogra-phic structuring. Molecular Ecology 12 2817-2833. 

The intent of the authors (subject matter experts) was to review the published literature and to determine the impact of contamination of our drinking water with CWAs, whether in warfare or by terrorist activity. 

DoE (1994a) Contaminated Land Research Report 1, A Framework for Assessing the Impact of Contaminated Land on Groundwater and Surface Water , (Two Volumes), DoE (London). 

Prediction of bioavailable heavy metal concentration appears to be more complex, and appropriate normalizing factors still have to be evaluated. Until predictive methods for determining bioavailability of contaminants in sediments can be validated, empirical measurements of body burden and effects as determined by the toxicity test and field monitoring provide the most direct approach for evaluating the impact of contaminated sediment in the aquatic environment (Fava et al., 1987). 

Concerns over the potential risks to human health from exposure to contaminated soils have fired a broader debate over the wider social impacts of contaminated land on the quality of life. Many former industrialised areas form a focus for low cost or social housing, driven partly by positive issues such as access to work opportunities and partly by negative issues such as low land values. Some of the more deprived communities have resided in these contaminated areas. In addition to this social issue of environmental justice, a wider recognition of the importance of a sense of place and community attachment, and a broader interpretation of environment beyond the strictly technical one, are bringing issues like the value of urban ecology, the importance of industrial heritage and the need for wider stakeholder involvement to the fore. 

Contaminants may travel through the atmosphere, soil, groundwater and superficial waters affecting the organisms that inhabit these media. The exposure modeling quantifies the impacts of contaminants as they travel through more than one of these compartments. 

These tests aim to assess the impact of contaminated flowers or honeydew on foraging bees. They can be requested when particular effects (toxicity for larvae, long-term delayed effects, disorientation of bees) have been observed during field tests. In France, the CEB 129 method is used. 

Lipophilicity has emerged as the key parameter for assessing the potential environmental impact of contaminants. This property constitutes a measure for the preference of a substance for either aqueous or non-aqueous phases. The partitioning between compartments of different polarity determines the rate and the direction of the transport of chemicals in the environment and thus their accumulation in some of its components. Therefore, lipophilicity appears in QSARs in environmental studies in two ways - as an endpoint by itself as well as a chemical descriptor to model further distribution-related parameters. 

T-RFLP could also be used to follow shifts in bacterial community structure. Turpeinen et al. [79], used this technique to study the impact of contamination by arsenic, chromium and copper on microbial communities. The T-RFLP analysis showed that contamination with metals induces permanent changes in the microbial community structure. Rousseaux et al. [80] also re-... 

CERCLA has set up a remedial scheme for analyzing the impact of contamination on sites under a hazard ranking system, from which a list of prioritized disposal and contaminated sites is compiled. This list is known as the National Priorities List (NPL). The NPL identifies the worst sites in the nation, based on such factors as the quantities and toxicity of wastes involved, the exposure pathways, the number of people potentially exposed, and the importance and vulnerability of the imderlying groundwater. 

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