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Scientific information is required to make environmental policy that will enhance and protect the health of ecosystems. The issues placed on the policy agenda come from the interactions amongst stakeholders, decision makers and other influential actors. These actors include government, civil society, private sector, and planning regimes. Ideally, scientific research then provides members of the policy community with assessed options upon which final decisions are eventually made. <br /><br /> This process is more complex than most in the realm of environmental policy because the goal of sustainability, commonly advocated by government, should serve to guide choices regarding policy alternatives. Sustainability, in practice, requires simultaneous attention to factors such as the needs of present and future generations; consideration for vastly differing social, environmental, and economic perspectives; and development of effective strategies to deal with the interconnectedness and complexity of the world. Management of these factors demands an ability to collect and process massive amounts of information at different temporal and spatial scales. The complexity of such situations means that there are instances when scientific information is not available and decisions need to be made quickly. <br /><br /> Using a case study approach, this thesis investigates the Canadian Wildlife Service?s attempts to achieve its mandate of conserving migratory birds while approving bismuth as an alternative to lead that was shown to cause poisoning of birds. This case study serves as an example of the tension between limited or ambiguous scientific information and urgent decisions. The chosen policy alternative to the use of lead shot was the approval of bismuth shot as a non-toxic substitute in 1997 and banning the use of lead shot nationwide in 1999. This decision to approve bismuth shot was based upon a few studies that were interpreted in a way that made it appear benign when compared to lead. This thesis examines the implications of this decision by conducting a comprehensive literature review of bismuth?s interactions with soil, vegetation, and animals, with some medical information on humans to put findings into an anthropocentric context. Also, analysis has been carried out on the results of a four-year study on bismuth in a wetland site near Kingston, Ontario, Canada. Finally, a ?post-normal perspective? exploration of the Canadian Wildlife Service revealed that decisions could be harmful to both human and environmental health if the values and knowledge of stakeholders are not taken into account and if uncertainties are overlooked. <br /><br /> Key findings generated by the literature review were potential chronic impacts to the neurological and reproductive health of animals exposed to bismuth shot. In turn, bismuth-contaminated meat may be a source of bismuth for humans and therefore guidelines for consumption should be investigated. Also, soil and vegetation have also been shown to accumulate bismuth, but it is unknown if it amounts to toxic levels. The wetland study helped to address the literature gap of bismuth?s fate in the environment. The mean concentration of bismuth in the soil after four years was 6. 40 µg/g, which was significantly higher than the control soil mean of 0. 42 µg/g. Ultimately, in terms of environmental policy, a ?post-normal perspective? offers three main tools for decision makers faced with urgent issues and uncertain facts. Namely, extended peer communities, acknowledgement and demonstration of uncertainty, and making values explicit.

Scientific information is required to make environmental policy that will enhance and protect the health of ecosystems. The issues placed on the policy agenda come from the interactions amongst stakeholders, decision makers and other influential actors. These actors include government, civil society, private sector, and planning regimes. Ideally, scientific research then provides members of the policy community with assessed options upon which final decisions are eventually made. <br /><br /> This process is more complex than most in the realm of environmental policy because the goal of sustainability, commonly advocated by government, should serve to guide choices regarding policy alternatives. Sustainability, in practice, requires simultaneous attention to factors such as the needs of present and future generations; consideration for vastly differing social, environmental, and economic perspectives; and development of effective strategies to deal with the interconnectedness and complexity of the world. Management of these factors demands an ability to collect and process massive amounts of information at different temporal and spatial scales. The complexity of such situations means that there are instances when scientific information is not available and decisions need to be made quickly. <br /><br /> Using a case study approach, this thesis investigates the Canadian Wildlife Service?s attempts to achieve its mandate of conserving migratory birds while approving bismuth as an alternative to lead that was shown to cause poisoning of birds. This case study serves as an example of the tension between limited or ambiguous scientific information and urgent decisions. The chosen policy alternative to the use of lead shot was the approval of bismuth shot as a non-toxic substitute in 1997 and banning the use of lead shot nationwide in 1999. This decision to approve bismuth shot was based upon a few studies that were interpreted in a way that made it appear benign when compared to lead. This thesis examines the implications of this decision by conducting a comprehensive literature review of bismuth?s interactions with soil, vegetation, and animals, with some medical information on humans to put findings into an anthropocentric context. Also, analysis has been carried out on the results of a four-year study on bismuth in a wetland site near Kingston, Ontario, Canada. Finally, a ?post-normal perspective? exploration of the Canadian Wildlife Service revealed that decisions could be harmful to both human and environmental health if the values and knowledge of stakeholders are not taken into account and if uncertainties are overlooked. <br /><br /> Key findings generated by the literature review were potential chronic impacts to the neurological and reproductive health of animals exposed to bismuth shot. In turn, bismuth-contaminated meat may be a source of bismuth for humans and therefore guidelines for consumption should be investigated. Also, soil and vegetation have also been shown to accumulate bismuth, but it is unknown if it amounts to toxic levels. The wetland study helped to address the literature gap of bismuth?s fate in the environment. The mean concentration of bismuth in the soil after four years was 6. 40 µg/g, which was significantly higher than the control soil mean of 0. 42 µg/g. Ultimately, in terms of environmental policy, a ?post-normal perspective? offers three main tools for decision makers faced with urgent issues and uncertain facts. Namely, extended peer communities, acknowledgement and demonstration of uncertainty, and making values explicit.

The objective of this study was to determine the effect of time, temperature and organic matter on disinfectant efficacy. Staphylococcus aureus (SA) and Salmonella Typhimurium (ST) were used as organisms to represent Gram positive and Gram negative bacteria, respectively, commonly found in poultry housing. Three independent experiments evaluated the effect of temperature, time, and organic matter on the efficacy of working concentrations of disinfectants against representative organisms found in commercial poultry housing. Quaternary ammonium, chlorhexidine, phenolic and binary ammonium based solutions represented disinfectants commonly used within the poultry industry. Results from these experiments indicated that long term storage of disinfectants will reduce their efficacy against SA. However, a reduction (p ≤ 0.05) in efficacy was observed with the phenolic compound against ST at elevated temperatures. Following the inclusion of organic matter (OM), reduced (p ≤ 0.05) efficacy of all disinfectants was observed in a dose dependent manner against both organisms, with the exception of the phenolic compound against SA. Fresh disinfectant performed better (p ≤ 0.05) in the presence of OM than 30 wk old disinfectant. These results emphasize the need to use fresh disinfectants and that OM should be removed prior to disinfection. We also evaluated the effect of bismuth citrate, lactose and citric acids on the development of necrotic enteritis in broilers. Clostridium perfringens’ associated necrotic enteritis in poultry causes significant loss and increased morbidity in the industry. Due to the reduced usage of antibiotic growth promoters, the incidence of necrotic enteritis has increased. These experiments evaluated different levels of bismuth citrate and bismuth citrate with lactose or citric acid added, on lesion development, bacterial intestinal colonization of C. perfringens and pH levels in the gut of broilers orally challenged with C.perfringens. Results from this investigation indicate that bismuth citrate at 100 ppm and 200 ppm caused a reduction (p ≤ 0.05) in C. perfringens colonization and intestinal lesion development. The addition of dietary lactose to bismuth citrate enhanced the effect of bismuth citrate on intestinal lesion development. These data suggest that bismuth citrate alone or in combination with dietary lactose will reduce intestinal lesion development in broilers with necrotic enteritis.

¡@¡@¡@¡@¡@¡@¡@¡@¡@¡@¡@¡@¡@Abstract This paper presents an integrated batch-produced (Bi, Sb)2Te3 micro thermoelectric cooler(£g-TEC) fabricated by electrochemical MEMS technology. To optimize the thermal conductivity of (Bi, Sb)2Te3 thin layers, a cathode with tunable rotary speed has been designed in the electroplating system to well control the thin film deposition rate and uniformity.The column-type micro thermoelectric thin films fabricated using electrochemical-deposited and patterned using photolithography processes. The thermoelectric thin films made of N-type Bi2Te3 and P-type Sb2Te3 with an average thickness of 5£gm, are connected using Cr/Au layers at the hot junctions and cold junctions. The measured Seebeck coefficient and electrical resistivity of the thermoelectric thin films,are -52£gV/K and 2.52¡Ñ10-5£[m(N-type, power factor of 0.11mW/K2m),and 71£gV/K and 1.91¡Ñ10-5£[m( P-type, power factor of 0.26mW/K2m) after annealing at 250¢J.Under the circumstances that voltage of 2-5 volts is driven, the upper and lower levels electrode shows tentatively that there is 0.7¢Jof difference in temperature.

This paper presents an integrated column-type micro thermoelectric cooler (£g-TEC) constructed with serial connected p-type antimony-tellurium (Sb2Te3) and n-type bismuth-tellurium (Bi2Te3) micro pillars deposited by electrochemical deposited technology. To optimize the power factor, density and uniformity of the TE films and to enhance the reproducibility of £g-TEC device, a cathode with tunable rotary speed and with accurate current controller has been designed in the electroplating system of this research. The electroplating deposited Bi2Te3 and Sb2Te3 with an average thickness of 8 £gm, are connected using Cr/Au layers at the hot junctions and cold junctions. The measured Seebeck coefficient and electrical resistivity are -86 £gV/K and 16 £g£[-m for Bi2Te3 films after annealed at 250¢XC, and are 68 £gV/K and 30 £g£[-m for Sb2Te3 films after annealed at 200¢XC. The optimized power factors of the n-type (2.64¡Ñ10-4 W/K2m) and p-type (2.64¡Ñ10-4 W/K2m) telluride compounds have been demonstrated in this paper. Under 5 volts driven, the integrated £g-TEC device shows average cooling achieved is about 1.3 ¢XC.

Thèse de doctorat : Physique : Metz : 1999. / 1999METZ038S. 102 ref.

Thèse de doctorat : Spectrochimie, molécules, solides, réactivité : Lille 1 : 2000. / Résumé en français et en anglais. Bibliogr. en fin de chapitres.

Reproduction de : Thèse de doctorat : Science des Matériaux : Lille 1 : 2005. / N° d'ordre (Lille 1) : 3703. Résumé en français et en anglais. Titre provenant de la page de titre du document numérisé. Bibliogr. p. 186-193.

This thesis describes investigations performed into the growth and characterisation of Bi-based (Bi₂Sr₂Ca_n-1Cu_nO_{2n + 4 + x}, n=2, 3) ceramic superconducting material in the form of thin films, about 0.5μm thick, grown on single crystal MgO, LaAIO₃ and SrTiO₃ substrates by r.f. magnetron sputtering. The effect of oxygen content on the Pb doped Bi-2223 (n=3) phase was also studied by changing the cooling process and by annealing in different partial pressures of oxygen at ambient pressure. The films produced have been assessed by considering their initial composition where it is found that Bi/Sr ratios can be between 0.9<Bi/Sr<1 for the Bi-2212 (n=2) phase, while for the Bi-2223 phase the Bi-content should be below 1.9 or lower than the Sr-content, for the films not to peel off the substrate during high temperature annealing. T_{c- zero} of around 80K is achievable for (Ca + Sr)/Bi ratios between 1.4 and 1.65 while T_{c- onset} remains above 90K for Bi-2212 films. However, the best superconducting properties can be obtained for a (Ca + Sr)/Bi ratio which is quite close the nominal composition. The use of a heavily Pb doped target is an effective way of Pb doping Bi-2223 thin films. A Bi-content of 1.4<Bi<1.8 in as deposited films may provide almost single phase Bi-2223 thin films with Tc values running from 105.5K to 109.5K and Jc>10,sup>4</sup>A/cm² at 77K. The effect of the initial Pb content and annealing conditions on the formation of the Bi-2223 phase was investigated. It was found that high Pb content (0.9<Pb/Bi<1.5) lowers the formation temperature appreciably and increases the range of sintering temperature (to at least 10K). The Bi-2223 phase starts to form at 835°C from the initial phases (Bi-2212, CuO and Ca₂PbO₄) formed below 835°C and its fraction increases with increasing sintering temperature up to 862°C, while the fraction of initial phases decreases. An annealing duration of 30 min. has provided highly oriented films with c-axis perpendicular to the substrate surface and sharp superconducting transition (<5K). Although Pb/Bi ratio is not critical in the range studied, when it is above 1.3 slow heating and cooling is necessary to prevent retention of excess Ca₂PbO₄ in the film after sintering. On LaAIO₃ and SrTiO₃ perovskite substrates, T_c is at least 5K lower than in the case of MgO. Nevertheless, LaAIO₃ can provide good microstructure with a critical current density, of 5x10⁴A/cm² at 77K. The direction and the range of variation of T_c in Bi-2223 films with oxidising process can be related to both the film composition (especially Bi and Pb content) and initial oxygen content. The variation range of T_c with oxidising is controlled by the Pb content. However, the maximum variation is around 4K at ambient pressure. Radiation response measurements were carried out on films patterned into a 150μm wide, and 1 cm long meander-type structure using standard photolithography and wet chemical etching in EDTA. The results showed that the optical response using a continuous wave (cw) He-Ne laser is bolometric, while the microwave response using a 34.5 GHz Gunn diode microwave generator contains a non bolometric component. Such polycrystalline Bi-based high T_c thin films may have interesting applications as sensitive microwave detectors, but they are not particularly good for microwave applications because of their high surface resistance, Rs, at microwave frequencies.