<p>Catalytic combustion is an environmentally friendlytechnique to combust fuels in e.g. gas turbines. Introducing acatalyst into the combustion chamber of a gas turbine allowscombustion outside the normal flammability limits. Hence, theadiabatic flame temperature may be lowered below the thresholdtemperature for thermal NO_Xformation while maintaining a stable combustion.However, several challenges are connected to the application ofcatalytic combustion in gas turbines. The first part of thisthesis reviews the use of catalytic combustion in gas turbines.The influence of the fuel has been studied and compared overdifferent catalyst materials.</p><p>The material section is divided into two parts. The firstconcerns bimetallic palladium catalysts. These catalysts showeda more stable activity compared to their pure palladiumcounterparts for methane combustion. This was verified both byusing an annular reactor at ambient pressure and a pilot-scalereactor at elevated pressures and flows closely resembling theones found in a gas turbine combustor.</p><p>The second part concerns high-temperature materials, whichmay be used either as active or washcoat materials. A novelgroup of materials for catalysis, i.e. garnets, has beensynthesised and tested in combustion of methane, a low-heatingvalue gas and diesel fuel. The garnets showed some interestingabilities especially for combustion of low-heating value, LHV,gas. Two other materials were also studied, i.e. spinels andhexaaluminates, both showed very promising thermal stabilityand the substituted hexaaluminates also showed a good catalyticactivity.</p><p>Finally, deactivation of the catalyst materials was studied.In this part the sulphur poisoning of palladium, platinum andthe above-mentioned complex metal oxides has been studied forcombustion of a LHV gas. Platinum and surprisingly the garnetwere least deactivated. Palladium was severely affected formethane combustion while the other washcoat materials were mostaffected for carbon monoxide and hydrogen.</p><p><b>Keywords:</b>catalytic combustion, catalyst materials,palladium, platinum, bimetallic, garnet, spinel, hexaaluminate,deactivation, sulphur, poisoning, diesel, methane,hydrocarbons</p>

Thesis (D.P.H.)--University of Alabama at Birmingham, 2007. / Title from PDF title page (viewed on Feb. 19, 2010). Includes bibliographical references.

M.Tech. Business Administration. Business School. / This study investigates the extent to which levels of awareness of lead poisoning among mine workers at the Exxaro lead and zinc mine in Namibia correlate to their levels of compliance. Specifically, the study investigates the extent to which mine workers are aware of lead poisoning and whether this knowledge influences their attitudes towards compliance to regulations on handling hazardous materials.

Polymer electrolyte membrane (PEM) fuel cells are promising alternative green power source for mobile, portable and stationary applications. However, their cost, durability, and performance are impacted by their sensitivity to impurities in fuel stream. Carbon monoxide (CO), an impurity commonly present in the hydrogen gas produced from hydrocarbon fuels, is known to have a significant degrading effect on PEM fuel cell performance because CO has a strong affinity to the platinum-based catalyst. At present, most studies in literature are limited to either experimental or simplified-dimensional analysis/modeling. In this thesis research, a three-dimensional (3D) multiphase PEM fuel cell model with the CO poisoning and O2 bleeding is developed based on the conservation laws for mass, momentum, energy, and species, and implemented in the commercial software Fluent (6.3.26) through the user-defined functions. Numerical simulations are conducted to simulate a single PEM fuel cell including flow channels, gas diffusion layers, catalyst layers, and PEM. The simulation results are compared with experimental data favorably. The result shows that the reaction rate of hydrogen in the anode catalyst layer is higher near the membrane layer, decreasing towards the gas diffusion layer (GDL) interface, and the reaction rate in general is higher in the inlet region and decreases towards the exit region of the flow channel. It means that the outlet of anode catalyst layer next to the flow channel and GDL has suffered the most significant poisoning effect. The result helps optimize the design of anode catalyst layer by embedding more platinum on the most poisoned area to increase available surface for hydrogen adsorption; similarly, reducing platinum loading on the less poisoned area. The fuel cell performance can be almost fully recovered when switching the anode fuel mixture to pure hydrogen, though it takes a long period of time. The reaction rate of hydrogen decreases significantly along the flow channel when impurity mixture is provided; while there is little change along the channel for pure hydrogen fuel. Adding oxygen into the anode fuel mixture can mitigate CO poisoning, but there is a time delay when the oxygen is introduced into the anode stream and when the performance starts to recover. It is observed that at the beginning of oxygen introduced in the anode stream the recovery rate in the region adjacent to the channel outlet is faster than the rate in the region close to the inlet. This difference in the recovery rate gradually becomes smaller over time. In addition, the influence of CO poisoning and oxygen bleeding on multi-phase water is investigated. The influence on dissolved water is only clearly seen in the anode catalyst layer next to the land area. Finally, response to sudden load changes is simulated by changing cell voltage. It is found that the overshoot and undershoot are more significant at high current densities.

Darbo tikslas. Išsiaiškinti mirtinus apsinuodijimus Vilniaus apskrityje sukėlusias medžiagas, įvertinti jų saugumo laipsnį, vadovaujantis gautais rezultatais numatyti galimas prevencijos priemones. Tyrimo metodika. Tyrimo objektas – 2002 – 2006 m. Vilniaus apskrities stacionarines paslaugas teikiančiose įstaigose nuo apsinuodijimo mirusių pacientų Ligos istorijos bei suvestiniai Valstybinės ligonių kasos duomenys apie stacionarinėse ASPĮ apsinuodijusiems asmenims suteiktas paslaugas. Tyrimo metodas – statistinių duomenų analizė. Tyrimo metu analizuotos 283 Ligos istorijos iš 4 Vilniaus apskrities ASPĮ (Vilniaus greitosios pagalbos universitetinėje, Vilniaus miesto universitetinėje, Ukmergės ir Trakų ligoninės). Statistinės analizės metodai – statistinis duomenų reikšmingumas buvo tiriamas pagal χ2 kriterijų, laisvės laipsnių skaičių (df) bei statistinį reikšmingumą (p). Skirtumai tarp požymio laikyti statistiškai reikšmingi, kai p<0,05. Rezultatai. Tiriamuoju laikotarpiu mirtini apsinuodijimai alkoholiu ir jo surogatais sudarė didžiausią (66 proc.) visų tirtų apsinuodijimų dalį. Mirtini apsinuodijimai kitomis medžiagomis mažėjimo tvarka išsidėstė sekančiai: apsinuodijimai medikamentais, opioidais, nepatikslinta medžiaga, korozine medžiaga, nuodingomis dujomis, maistu, metalais bei techninėmis priemonėmis. Tiriamuoju laikotarpiu vidutinis mirštamumas keturiose ASPĮ buvo 2,2 proc. o vidutinis mirtingumas tarp Vilniaus apskrities gyventojų- 0,6 / 10’000. Didžiausiu (1,3 atv.)... [toliau žr. visą tekstą] / Aim of the study. To find out chemical agents caused lethal poisonings in Vilnius County, to assess chemical safety of these chemical products, and provide possible means of prevention. Methods. The retrospective cohort of 283 lethal poisoning cases was formed using data of four hospitals from Vilnius County in 2002-2006 years. The results were compared with data of State patient fund about all cases of acute poisonings during the same period. SPSS package and MS Excel program were used for statistical analysis. Data were analyzed according to the Chi criteria. Results. Most of lethal poisonings (66 %) were caused by ethyl alcohol and it’s surrogates; other chemical agents were (in declining order): different pharmaceuticals, opioids, unspecified chemical materials, corrosive agents, poisonous gas, food, metals, and technical materials. The average fatality ratio of acute poisonings treated in hospitals was 2.2 %, while the average mortality ratio from acute poisonings between Vilnius County inhabitants was 0.6/10000. The highest mortality ratio (1.3/10000) was found in Trakai municipality , and the lowest (0.2/10000) in– Švenčionys municipality. Half of deaths were in those between 45-64 years old. Due to early death more than 5000 life years were lost. Males accounted for more lethal poisonings cases (70%) than females. Alcohols and opioids as lethal poisonings agents were significantly higher in males than females (p<0.05). Death from corrosive agents and pharmaceuticals... [to full text]

Lead (Pb) is a known toxicant that affects young children. It is believed that old water reticulation systems are prone to lead leaching from the walls of lead pipes and fixtures where water is conveyed to households. Many households in Christchurch city particularly in the Northwestern and Central parts of the city contain old water reticulation systems thereby, putting children at considerable health risks. The purpose of this dissertation is to identify the hazards of lead exposure that comes from old water reticulation system of Northwest (NW) Christchurch water supply to households, characterize the health risks due to such contamination and, finally, to suggest possible ways to minimize the hazards. This is accomplished by conducting a systematic review of literature on the exposure patterns of lead from reticulation systems and a literature review of the possible dose response patterns of health effects of lead contamination from old water reticulation systems on children. Thus, this dissertation involves a literature based risk assessment of lead contamination of drinking water supply in the Northwest Christchurch Zone and particularly, its effects on young children. The selection process of the research studies is based on whether they offer accurate and suitable information on the risk of adverse mental function in infants and young children due to environmental lead exposure; whether the studies have been peer reviewed by qualified scientists; whether the results are confirmed by other studies; and involves only human subjects. Future research may consider whether lead levels in drinking water are seasonal; whether these values are significant to health or, the possible role of the government in tightening product controls when monitoring the availability and health risk of high lead drinking water supply plumbing products available in the New Zealand market.

Lead is a serious developmental neurotoxin with the capacity to interrupt brain development and impair functioning. Since at least 1930 numerous case studies in American, Canadian and Australian literature have identified lead based paint in the home as a source of poisoning for young children; and since at least 1990 evidence has shown that it is the lead dust from deteriorating paint in older homes and renovating activities that is the primary source of chronic exposure for young children today. Not much is known about the extent of childhood lead poisoning in Canada. Gaps in our understanding include a lack of national survey data on childhood blood lead levels and an absence of reliable data to determine the era of housing that poses the greatest risk. This thesis posits that despite this paucity of research knowledge there is evidence to suggest that populations of vulnerable children continue to be harmed by exposure to historic sources of lead, such as lead-based paint found in older housing stock. This thesis examines the evidence to support this contention by critically analyzing the Canadian public health response to the issue of childhood lead poisoning. Specific attention is paid to discourse corresponding to lead-based paint, the putative major pathway of exposure for children ages 1 to 5 years. Using Foucault’s genealogical/archaeological approach, as elaborated upon by Rawlinson (1987) this thesis discusses the socio-political and economical processes that shaped health care knowledge regarding childhood lead poisoning in Canada and influenced the way knowledge was produced and used by health care providers and policy makers. The analysis is assisted via a comparison of Canadian public health discourse with American discourse, with an emphasis on discourse appearing in the post leaded gasoline era (1990-2008). The strength of a Foucauldian archaeological/genealogical analysis for nursing research and particularly for this analysis is in its focus on discourse, surfaces of emergence, transformations, mutations, contingencies, events, recognition of power/knowledge strategies, descriptions of discipline technologies and consequences, and suggested possibilities of resistance. This thesis proposes that surveillance data constituted both a product and acatalyst of the dominant view on childhood lead poisoning occurring from residential sources and posits that a lack of Canadian context specific surveillance data was the major “policing” factor limiting Canadian public health discourse. Further, privileged access to blood lead survey data maintained the view that childhood lead poisoning was a problem of the past or an American problem. Third, tensions among Canada’s two federal agencies which hold primary responsibility for lead, health and housing resulted in a weakened response whereby, to date, no legislation exists to protect vulnerable populations of Canadian children from exposure to historic sources of lead in residential dwellings.

Ruthenium(III) acetylacetonate was employed for the first time as homogeneous catalyst in the hydrolysis of sodium borohydride. Ruthenium(III) acetylacetonate was not reduced by sodium borohydride under the experimental conditions and remains unchanged after the catalysis, as shown by FT-IR and UV-Vis spectroscopic characterization. Poisoning experiments with mercury, carbon disulfide or trimethylphosphite provide compelling evidence that ruthenium(III) acetylacetonate is indeed a homogenous catalyst in the hydrolysis of sodium borohydride. Kinetics of the ruthenium(III) acetylacetonate catalyzed hydrolysis of sodium borohydride was studied depending on the catalyst concentration, substrate concentration and temperature. The hydrogen generation was found to be first order with respect to both the substrate concentration and catalyst concentration. The activation parameters of this reaction were also determined from the evaluation of the kinetic data: activation energy / Ea = 25.6 &amp / #61617 / &amp / #61472 / 1.3 kJ.mol-1, the enthalpy of activation / &amp / #8710 / H# = 24.6 &plusmn / 1.2 kJ.mol-1 and the entropy of activation &amp / #8710 / S# = -170 &plusmn / 5 J&amp / #61655 / mol-1&amp / #61655 / K-1. Ruthenium(III) acetylacetonate provides the lowest activation energy ever found for the hydrolysis of sodium borohydride. Ruthenium(III) acetylacetonate was found to be highly active catalyst providing 1183 total turnovers in the hydrolysis of sodium borohydride over 180 min before they are deactivated. The recorded turnover frequency (TOF) is 6.55 min-1.

The goal of current solid oxide fuel cell (SOFC) research is to design electrode materials and other system components that permit the fuel cell to be operated in the 400-700ºC range. Cell performance in this lower temperature range is limited by the oxygen reduction process at the SOFC cathode and by multiple contamination processes. The work presented demonstrates that Raman spectroscopy, a form of vibrational spectroscopy, can provide structural and compositional information complementary to that from traditional characterization methods. Initial experiments into the oxygen reduction mechanism on SOFC cathodes were unable to detect surface oxygen species on selected perovksite-based SOFC cathode materials. However, the Raman signal from the cathode surface was able to be enhanced by depositing silver or gold nanoparticles on the cathode, creating the so-called surface-enhanced Raman scattering (SERS) effect. The Raman sample chamber was also used to study two possible electrode contamination processes. First, the deposition of carbon on nickel and copper anodes was observed when exposed to different hydrocarbon fuel gases. Second, the poisoning of an SOFC cathode by chromium-containing vapor (usually generated by stainless steel SOFC system components) was monitored. Overall, Raman spectroscopy was shown to be useful in many areas crucial to the development of practical, cost-effective SOFCs. The techniques developed here could also be applied to other high temperature electrochemical and catalytic systems.

Solid oxide fuel cells (SOFCs) are electrochemical devices based on solid oxide electrolytes that convert chemical energy in fuels directly into electricity via electrode reactions. SOFCs have the advantages of high energy efficiency and low emissions and hold the potential to be the power of the future, especially for small power generation systems (1-10 kW). Another unique advantage of SOFCs is the potential to directly utilize hydrocarbon fuels such as natural gas through internal reforming. However, all hydrocarbon fuels contain some sulfur compounds, which transform to hydrogen sulfide (H2S) in the reforming process and dramatically degrade the performance of the existing SOFCs. In this study, the interactions between sulfur contaminant (in the form of H2S) and the anodes for SOFCs were systematically investigated in order to gain a fundamental understanding of the mechanism of sulfur poisoning and ultimately to achieve rational design of sulfur-tolerant anodes. The sulfur poisoning behavior of the state-of-the-art Ni-YSZ cermet anodes was characterized using electrochemical measurements performed on button cells (of different structures) under various operating conditions, including H2S concentration, temperature, cell current density/terminal voltage, and cell structure. Also, the mechanisms of interactions between sulfur and the Ni-YSZ cermet anode were investigated using both ex situ and in situ characterization techniques such as Raman spectroscopy. Results suggest that the sulfur poisoning of Ni-YSZ cermet anodes at high temperatures in fuels with ppm-level H2S is due not to the formation of multi-layer conventional nickel sulfides but to the adsorption of sulfur on the nickel surface. In addition, new sulfur-tolerant anode materials were explored in this study. Thermodynamic principles were applied to predict the stability of candidate sulfur-tolerant anode materials and explain complex phenomena concerning the reactivity of candidate materials with hydrogen sulfide. The enhanced sulfur tolerance for some candidate anode materials such as (Gd2Ti1.4Mo0.6O7) is attributed to the transition of the surface from metal oxides to sulfides (i.e., MoS2), which enhances the catalytic activity and increases the number of reaction sites.