BiophotonicE. coli O157:H7(BEC) was evaluated for growth and stability to evaluate the effectiveness of BEC as a tool to validate pathogen reduction interventions. Escherichia coliO157:H7 containing Xen14 and pAK1 lux plasmids were monitored for growth and stability over 10 d at 2.2˚C and 37˚C. Concentration of BECat 2.2˚C remained constant (P> 0.05) but photonic emissions (RLU/s) changed (P<0.05), resulting in a positive correlation between RLU/s and CFU/mL (P< 0.01; r=0.5718). BEC grown at 37˚C yielded no change after a decrease on day 2 (P>0.05). In phase I, purge was monitored for photonic emission after trim was inoculated with BEC. BECwas found at 4 h in Combo C and D. Phase II purge collection used inoculated trim indicative of trim used currently in the beef industry stored in simulated combos. Neither photonic emission nor CFU’s were enumerated in phase II.

This thesis deals with the problem of determining the reasons behind the purge conducted by various high officials in the Nazi regime on June 30-July 2, 1934.

Polymer Electrolyte Membrane Fuel Cells (PEMFC) are promising power generating devices that use an electrochemical reaction to convert the energy from hydrogen fuel into usable electricity. One cell produces a small voltage so many cells are combined in series in order to produce a useful voltage, this configuration is referred to as a stack. Hydrogen is supplied to the anode of the stack in amounts greater than the electrochemical reaction requires to guarantee that enough hydrogen is available for every cell in the stack and to provide enough pressure throughout the cell flow channels for good mass transfer. For reasonable fuel efficiency, the anode outlet gas containing unconverted hydrogen is recycled (or recirculated) back to the anode inlet. PEMFC performance is highest when pure hydrogen fuel is supplied, however, nitrogen at the cathode will permeate through the membrane and accumulate in the anode gas with recirculation. Nitrogen buildup dilutes the hydrogen gas which adversely affects fuel cell performance at the anode. Also, in practical applications hydrogen-rich gas produced from reformed methane, called reformate, is used as the fuel. Reformate contains impurities such as, nitrogen, carbon dioxide, carbon monoxide, and sulfur compounds. This thesis will focus on trace levels of carbon monoxide entering in the hydrogen fuel stream, and the impact of contaminant build-up due to anode recirculation. Carbon monoxide adsorbs readily onto the platinum catalyst sites, called poisoning, thus decreasing PEMFC performance. In efforts to minimize the buildup of impurities and crossed over nitrogen, a portion of the anode outlet gas is periodically and continuously purged to the exhaust. How often the outlet gas is purged depends on a variable called the purge fraction. The purpose of this research is to study the effect of purge fraction on PEMFC performance, measured by the average cell voltage, for a Hydrogenics 10 cell stack. The operating parameters used for testing and the experimental apparatus were designed to mimic a Hydrogenics 8kW Hydrogen Fuel Cell Power Module. A pump connected between the anode outlet and anode inlet form the anode recirculation loop. In Phase 1 of the test program the effect of purge in the absence of carbon monoxide was studied to see if hydrogen dilution from nitrogen crossover and accumulation would cause significant cell voltage degradation. In Phase 2 the effect down to 0.2 ppm carbon monoxide was evaluated. The results showed that nitrogen buildup, in the absence of carbon monoxide, did not significantly penalize the cell performance in the range of purge fractions tested. However, for the same purge fraction but with as little as 0.2 ppm carbon monoxide present, the voltage loss was significant. A discussion of the effect of purge on the impurity concentration and the associated cell voltage degradation is detailed with particular emphasis on carbon monoxide poisoning.

Polymer Electrolyte Membrane Fuel Cells (PEMFC) are promising power generating devices that use an electrochemical reaction to convert the energy from hydrogen fuel into usable electricity. One cell produces a small voltage so many cells are combined in series in order to produce a useful voltage, this configuration is referred to as a stack. Hydrogen is supplied to the anode of the stack in amounts greater than the electrochemical reaction requires to guarantee that enough hydrogen is available for every cell in the stack and to provide enough pressure throughout the cell flow channels for good mass transfer. For reasonable fuel efficiency, the anode outlet gas containing unconverted hydrogen is recycled (or recirculated) back to the anode inlet. PEMFC performance is highest when pure hydrogen fuel is supplied, however, nitrogen at the cathode will permeate through the membrane and accumulate in the anode gas with recirculation. Nitrogen buildup dilutes the hydrogen gas which adversely affects fuel cell performance at the anode. Also, in practical applications hydrogen-rich gas produced from reformed methane, called reformate, is used as the fuel. Reformate contains impurities such as, nitrogen, carbon dioxide, carbon monoxide, and sulfur compounds. This thesis will focus on trace levels of carbon monoxide entering in the hydrogen fuel stream, and the impact of contaminant build-up due to anode recirculation. Carbon monoxide adsorbs readily onto the platinum catalyst sites, called poisoning, thus decreasing PEMFC performance. In efforts to minimize the buildup of impurities and crossed over nitrogen, a portion of the anode outlet gas is periodically and continuously purged to the exhaust. How often the outlet gas is purged depends on a variable called the purge fraction. The purpose of this research is to study the effect of purge fraction on PEMFC performance, measured by the average cell voltage, for a Hydrogenics 10 cell stack. The operating parameters used for testing and the experimental apparatus were designed to mimic a Hydrogenics 8kW Hydrogen Fuel Cell Power Module. A pump connected between the anode outlet and anode inlet form the anode recirculation loop. In Phase 1 of the test program the effect of purge in the absence of carbon monoxide was studied to see if hydrogen dilution from nitrogen crossover and accumulation would cause significant cell voltage degradation. In Phase 2 the effect down to 0.2 ppm carbon monoxide was evaluated. The results showed that nitrogen buildup, in the absence of carbon monoxide, did not significantly penalize the cell performance in the range of purge fractions tested. However, for the same purge fraction but with as little as 0.2 ppm carbon monoxide present, the voltage loss was significant. A discussion of the effect of purge on the impurity concentration and the associated cell voltage degradation is detailed with particular emphasis on carbon monoxide poisoning.

In recent years, HVAC systems of commercial buildings imposed heavy load on power demand, especially during summertime on-peak periods. The HVAC power consumption of commercial buildings usually accounts for 40% of total which indicated huge potential for energy-savings if proper operation strategies can be implemented. In this research, three different operational strategies were studied in an attempt to conserve energy, namely: the Night Purge, Free Cooling,and Pre-cooling. They were simulated , under the local weather conditions, and then validated with full-scale experiments.The experimental results indicated that significant load-shifting effect can be experienced, which also warranted good engineering application potentials when coupled with other HVAC energy-savings operation strategies.

Le retour à meilleure fortune est un fait juridique résultant de l’amélioration soudaine de la situation patrimoniale d’un débiteur, par un gain à la loterie ou un héritage, le mettant en mesure de payer ses créanciers. Pris en compte dans la cession de biens sous l’Antiquité, le débiteur de bonne foi n’échappait à la prison pour dettes que contre l’abandon de ses biens et l’engagement de s’acquitter du reliquat dû après leur vente si la fortune venait de nouveau à lui sourire. Le droit positif n’accorde, aujourd’hui, que peu de place à ce fait juridique. En droit public, celui-ci constitue encore, dans le Code de l’action sociale et des familles ainsi que dans celui des collectivités territoriales, un critère de récupération des aides publiques. Et, en droit privé, la liberté contractuelle permet encore d’assortir la remise de dette d’une clause de retour à meilleure fortune afin d’organiser une réversibilité de l’abandon de créance. L’article 2284 du Code civil donne encore un effet juridique à cette situation en intégrant au gage commun des créanciers tous les biens nouveaux acquis par le débiteur. Partant de là, le retour à meilleure fortune devrait profiter aux créanciers. Mais ce principe est aujourd’hui malmené par un droit « à ne pas payer ses dettes ». Qu’il soit un consommateur ou un professionnel, le débiteur de bonne foi peut obtenir la purge de ses dettes. L’obligation de paiement du débiteur est alors éteinte y compris si la fortune vient de nouveau à lui sourire. Seuls les créanciers dont les droits sont juridiquement préservés des effets de la purge peuvent encore prétendre à un paiement dans une telle situation. Pour l’essentiel, le débiteur conserve donc l’acquis de son retour à meilleure fortune. D’ailleurs, la Commission européenne a demandé aux Etats-membres de l’Union d’encourager le rebond du débiteur par une politique en faveur de la seconde chance. Le législateur français a ainsi adopté différentes mesures en faveur du rebond pour encourager celui qui a échoué à retenter sa chance. Les présents travaux envisagent donc les incidences juridiques du retour à meilleure fortune en distinguant les situations dans lesquelles il est valorisé de celles où il est neutralisé ; avant d’aborder les mesures en faveur du rebond du débiteur. / Return to better fortune is a legal item, consisting in a better financial state to the debtor by lottery or by inheritance. In this way, the creditors can obtain payment if the debtor’s situation happens to improve suddenly. A long with the transfer of property in Antiquity, the debtor in good faith could only avoid prison by abandoning his property and committing to pay off the balance due following its sale if fortune were again to smile on him. These days, the civil law contains indirect echoes of this concept. Today, the law accords but little room to this payment cause of action against a debtor. It is true that, under public law, it still qualifies as a criterion for recovery of public aid in the family and social Code as well as in the local authorities Code. And under private law, freedom of contract allows deferral of debt to be made subject to a return to better fortune clause so as to organize reversibility of abandoning property. Article 2284 of the Civil code includes all newly acquired property within a general pledge to creditors. In this way, return to better fortune should be profitable to creditors: they can obtain payment. But, for the main part, this concept is today ill-supported by a law “not to pay one’s debts”. Whether to be a consumer or a professional, the debtor in good faith can obtain purge of his debts. The debtor’s obligation to pay is thus extinguished, even if fortune were again to smile on him. Only creditors whose rights can be preserved juridically, by purge of this debts, are alleged to be paid in such a situation. But for the main part, the debtor conserves the fruit of his return to better fortune. Such policy in favor of a second chance, sought by the European institutions, has lead to the French legislator adopting recovery-favorable measures: the taking over of a company in difficulty has been favored and reintegration of the failed facilitated. Certain hurdles to recovery have also been removed in this research : on the one hand, return to better fortune valued, on the other hand, this situation neutralized ; before taking up the actions in favor of a second chance for the debtor.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Neste trabalho desenvolveu-se uma metodologia analítica para determinação do teor de trialometanos THMs em amostras de águas potáveis, utilizando a técnica de purga e armadilha acoplada à cromatografia a gás (GCPT). Os THMs são subprodutos da cloração da água que devem possuir um limite máximo de 100 &mu;g.L-1 segundo a legislação brasileira, estes compostos são suspeitos carcinogênicos humanos com base em estudos em animais de laboratório. A técnica de purga e armadilha extrai eficientemente estes compostos da água e a separação no cromatógrafo a gás ocorre utilizando coluna de leve polaridade e detector por captura de elétrons. Este detector é seletivo e o mais sensível para estes compostos halogenados. A metodologia desenvolvida foi validada nos itens de: linearidade, seletividade, exatidão, precisão, limite de quantificação, limite de detecção e robustez. O limite de detecção para os THMs foi menor do que 0,5 &mu;g.L-1. A exatidão e precisão foram adequadas para ensaios de compostos traços. As amostras de água potável foram coletadas na cidade de Suzano-SP, que pertence à região do Alto do Tietê, nesta região nas margens do rio a vegetação é predominante. Entre todos os THMs, o composto encontrado na água potável em maiores concentrações foi o clorofórmio onde os resultados quantitativos, utilizando esta metodologia apresentaram teores entre 15,9 à 111,0 &mu;g.L-1 em águas potáveis. / This work shows an analytical methodology developed and optimized to determine trihalomethanes level THMs, in drinking water samples, using purge and trap coupled to gas chromatography (GC-PT). THMs are byproducts water chlorination, these compounds must have a maximum of 100 &mu;g.L-1 under Brazilian law, due these compounds be suspected human carcinogens base on studies in laboratory animals. The technique of purge and trap efficiently extracts these compounds from water, and the gas chromatograph separates the THMs. The GC uses a light polarity column and electron capture detector. This detector is selective and more sensitive in the detection of these compounds. The methodology was validated in terms of: linearity, selectivity, accuracy, precision, quantification limit, detection limit and robustness. The detection limit was less than 0,5 &mu;g.L-1. The accuracy and precision were adequate for testing the trace compounds. The drinking water samples were collected in the city of Suzano-SP, which belongs to Alto do Tietê, in this region lay Tietê river with predominant vegetation. The THMs compound found in drinking water at higher concentrations was chloroform where the spread of values found between 15,9 to 111,0 &mu;g.L-1 in drinking water.

Neste trabalho desenvolveu-se uma metodologia analítica para determinação do teor de trialometanos THMs em amostras de águas potáveis, utilizando a técnica de purga e armadilha acoplada à cromatografia a gás (GCPT). Os THMs são subprodutos da cloração da água que devem possuir um limite máximo de 100 &mu;g.L-1 segundo a legislação brasileira, estes compostos são suspeitos carcinogênicos humanos com base em estudos em animais de laboratório. A técnica de purga e armadilha extrai eficientemente estes compostos da água e a separação no cromatógrafo a gás ocorre utilizando coluna de leve polaridade e detector por captura de elétrons. Este detector é seletivo e o mais sensível para estes compostos halogenados. A metodologia desenvolvida foi validada nos itens de: linearidade, seletividade, exatidão, precisão, limite de quantificação, limite de detecção e robustez. O limite de detecção para os THMs foi menor do que 0,5 &mu;g.L-1. A exatidão e precisão foram adequadas para ensaios de compostos traços. As amostras de água potável foram coletadas na cidade de Suzano-SP, que pertence à região do Alto do Tietê, nesta região nas margens do rio a vegetação é predominante. Entre todos os THMs, o composto encontrado na água potável em maiores concentrações foi o clorofórmio onde os resultados quantitativos, utilizando esta metodologia apresentaram teores entre 15,9 à 111,0 &mu;g.L-1 em águas potáveis. / This work shows an analytical methodology developed and optimized to determine trihalomethanes level THMs, in drinking water samples, using purge and trap coupled to gas chromatography (GC-PT). THMs are byproducts water chlorination, these compounds must have a maximum of 100 &mu;g.L-1 under Brazilian law, due these compounds be suspected human carcinogens base on studies in laboratory animals. The technique of purge and trap efficiently extracts these compounds from water, and the gas chromatograph separates the THMs. The GC uses a light polarity column and electron capture detector. This detector is selective and more sensitive in the detection of these compounds. The methodology was validated in terms of: linearity, selectivity, accuracy, precision, quantification limit, detection limit and robustness. The detection limit was less than 0,5 &mu;g.L-1. The accuracy and precision were adequate for testing the trace compounds. The drinking water samples were collected in the city of Suzano-SP, which belongs to Alto do Tietê, in this region lay Tietê river with predominant vegetation. The THMs compound found in drinking water at higher concentrations was chloroform where the spread of values found between 15,9 to 111,0 &mu;g.L-1 in drinking water.

Gas turbines operate with medium of very high temperatures, which requires using advanced materials for vanes and blades and sophisticated methods of their cooling. Other parts of the turbine have to be protected from contact with hot gases. Discs that hold vanes and blades are especially exposed to this danger. In order to avoid it certain improvements have to be applied: providing sealing air and adjusting geometry of the hub to make the ingress to the cavity (space between discs)more difficult. This thesis concerns CFD investigation of the influence of the amount of sealing air on sealing efficiency and on the flow in the main annulus. The first part concerned literature study. Phenomena of ingress and interaction between main flow and sealing air were described. Different methods of estimating efficiency were shown. The second part focused only on the main path of the gas, modeling secondary air as constant and uniform outflow through the opening. The aim was to investigate how the power and reaction rate depend on the secondary air. The results were also exported to be used as boundary condition in the second part of the thesis. The last part concerned only the cavity – conditions at the main annulus were taken from the main annulus solution. Pressure in specified locations was measured and used to calculate sealing efficiency. Results were compared with the theoretical equations from the literature study. A structure of the flow inside the cavity was analyzed for several different amounts of the sealing flow. A method of unsteady flow analysis was developed and described. It was successfully implemented which proves that the method is promising. However, some improvements are necessary to obtain stable solution and research in this field should be continued. / Turbopower