When a gas turbine operates in a particle laden environment, such as a desert, small solid particles are ingested into the engine. The ingested sand particles can cause damage to engine components and reduce the service life of the engine. Particle ingestion causes the erosion of metal blades and vanes, and, if the firing temperature is hot enough, deposition of molten particles in the hot sections of the engine. Both deposition and erosion phenomena can severely reduce overall engine performance. The Coefficient of Restitution (COR) is a measure of the particle-wall interaction, and has been widely used to quantify particle rebound characteristics in past particle impact studies. This work investigates the effects of temperature on sand particle impact characteristics by measuring the COR and other deposition related impact parameters. The first study presented as part of the dissertation contains a description of a novel method used to measure COR using a Particle Tracking Velocimetry (PTV) method. This is combined with Computational Fluid Dynamics (CFD) flow field to allow for an accurate determination of the particle impact velocity. The methodology described in this paper allows for measurement of the COR in a wide range of test conditions in a relatively simple manner. The COR data for two different sizes of Arizona Road Dust (ARD) and one size of glass beads are presented in this paper. Target material was stainless steel 304 and the impact angle was varied from 25 to 85 degrees. The second study details the first quantification of the COR of san particles at elevated temperatures. Temperatures used in this study were 533 K, 866 K, and 1073 K. In this study the mass flow rate through the experimental setup was fixed. This meant that velocity and temperature were coupled. Target material for this study was stainless steel 304 and the impact angle was varied from 30° to 80°. The COR was found to decrease substantially at the temperatures and velocity increased. It was determined that the decrease in COR was almost certainly caused by the increase in velocity, and not the decrease in temperature. The third study contains COR results at elevated temperatures. Significant improvements from the method used to calculate COR in the first paper are described. The particle used for these tests was an ARD sand of 20-40 μm size. Target materials used were stainless steel 304 and Hastelloy X. The particles impinged on the target coupon at a velocity of 28m/s. Tests were performed at three different temperatures, 300 K (ambient), 873 K, and 1073 K to simulate temperatures seen in gas turbine cooling flows. The angle of impingement of the bulk flow sand on the coupon was varied between 30° and 80°. A substantial decrease in COR was discovered at the elevated temperatures of this experiment. Hastelloy X exhibited a much larger decrease in COR than does stainless steel 304. The results were compared to previously published literature. The final study also used the ARD size of 20-40 μm. The target material was a nickel alloy Hastelloy X. Experiments for this study were performed at a constant velocity of 70m/s. Various temperatures ranging from 1073 K up to and including 1323 K were studied. Particle angle of impact was varied between 30° and 80°. Significant deposition was observed and quantified at the highest two temperatures. The COR of the ARD sand at the highest temperatures was found not to change despite the occurrence of deposition. At elevated temperatures, many of the particles are not molten due to sand's non-homogenous and crystalline nature. These particles rebound from the target with little if any change in COR. / Ph. D.

Many gas turbine engines operate in harsh environments where the engine can ingest solid particles. Particles can accelerate the deterioration of an engine and reduce the engine’s service life. Understanding particle interactions with the materials used in gas turbines, at representative engine conditions, can improve the design and development of turbomachinery operating in particle laden environments. Coefficient of Restitution (COR) is a measure of the particle/wall interactions and is used to study erosion and deposition. This study presents data taken using the Virginia Tech Aerothermal Rig. Arizona Road Dust (ARD) of 20-40 μm is injected into a flow field to measure the effects of temperature and velocity on particle rebound from a polished high temperature material coupon. The high temperature coupon was tested at different temperatures of ambient (300K), 873K, 1073K, 1173 K, 1223 K, 1273 K, and 1323 K while the velocity of the flow field was held constant at 28 m/s or 70 m/s. The impingement angle of the coupon was varied from 30° to 80° for each temperature tested. The results show an increase in deposition as the temperature approaches the melting temperature of sand. The results have also been compared to previously published literature. / Master of Science

Six studies were conducted to examine the role of endogenous opioid peptides in the regulation of ingestive behavior in the domestic fowl. In the first study, the dose-response relationships of two opioid antagonists, naloxone and naltrexone, were evaluated in Rock-Comish (RC) and Single-Comb White Leghorn (SCWL) cockerels. Naloxone and naltrexone decreased food and water intake in both stocks. In a separate experiment, the effect of naloxone on water intake was evaluated independent of food intake. Naloxone depressed water intake in normally hydrated and saline-loaded chicks. These results indicate endogenous opioid peptides influence food and water consumption independently in the domestic fowl. The sensitivities of RC and SCWL stocks to naloxone were compared in a second investigation. There was no difference in the efficacy of naloxone in attenuating ingestive behavior when the stocks were compared at either the same age or similar body weight. Therefore, genetic selection for meat or egg production has not significantly altered naloxone-sensitive opioid mechanisms regulating food and water intake in the domestic fowl. A third study extended the investigation of opioid regulation of ingestive behavior to Japanese quail (Coturnix coturnix japonica). Administration of naloxone attenuated feeding, but not drinking, suggesting that water in Japanese quail is not influenced by endogenous opioids. The fourth study was performed to determine whether opioid regulation of ingestive behavior in the domestic fowl is mediated at sites within the central nervous system or peripheral tissues. An initial experiment examined the effects of two opioid antagonists with differing ability to traverse the blood-brain barrier (bbb). Food and water intake were attenuated by both antagonists. However, at equally potent doses the antagonist which does not readily traverse the bbb (quaternary naloxone) was more effective than its congener which crosses the bbb (tertiary naloxone). Central administration of tertiary naloxone attenuated water consumption, but not feeding. No alterations in ingestive behavior were observed when these levels of tertiary naloxone were injected im. Therefore, these results suggest that opioid regulation of food intake occurs at sites outside the bbb, whereas water intake is at least, in part, centrally mediated. The remaining studies were conducted to identify the specific opioid receptor subtypes which mediate ingestive behavior in the domestic fowl. In the fifth study, ingestive responses to central (intracerebroventricular; ICV) and peripheral (im) administration of the mu agonist, morphiceptin, and the delta agonist, [Met⁵]·enkephalin, were studied. The mu and delta-opioid receptors are the receptors for which naloxone has the highest and lowest affinity, respectively. ICV administration of morphiceptin stimulated drinking, whereas im administration stimulated feeding. [Met⁵]·enkephalin stimulated food intake by both routes of administration. These results indicate that the mu opioid receptor mediates water intake in the central nervous system and food intake peripherally, while the delta-opioid receptor mediates food intake centrally and peripherally. Failure to detect central opioid mediation of food intake in previous studies was likely due to the low-affinity naloxone exhibits for the delta receptor. The final study examined the feeding, drinking, and temperature responses to ICV administration of ß-endorphin. ß-endorphin has equal affinity for the mu, delta, and epsilon opioid receptors. ICV administration of ß·endorphin induced increases in feeding, drinking, and colonic temperature in RC and SCWL. These studies indicate that endogenous opioid peptides influence food and water intake in the domestic fowl. Opioids appear to influence food and water consumption at sites within and outside the bbb, and via different receptor subtypes. Furthermore, there seems to be no difference in naloxone·sensitive opioid systems influencing ingestive behavior in meat and egg stocks of chickens. / Ph. D. / incomplete_metadata

Le pâturage, principal mode d’alimentation en zone tropicale, est souvent dévalorisé car il est associé à des performances animales jugées insuffisantes, et peut avoir des effets néfastes sur l’environnement. Même si l’alimentation à l’auge permet de meilleures productions, ce mode de conduite présente également des inconvénients, en termes d’investissements, de rentabilité économique, d’impact des rejets sur l’environnement et de qualité des produits. Une intensification de la conduite au pâturage semble donc une voie d’avenir, mais nécessite une meilleure connaissance de ce mode de conduite et de ses conséquences sur l’alimentation et les performances des animaux. Il apparait également nécessaire de comparer l’élevage au pâturage et à l’auge sur des critères homogènes, en dissociant les composantes de ces modes de conduite.L’objectif de la thèse est d’évaluer et de comparer la conduite au pâturage et la conduite hors sol, en tenant compte également de la distribution ou non de concentré, sur l’alimentation, la croissance, les caractéristiques d’abattage et la consommation d’eau. Dans un premier temps, nous avons étudié au cours d’une expérimentation, les effets de ces deux modes de conduite sur la croissance, les caractéristiques d’abattage et de carcasse de taurillons Créoles abattus à deux âges (précoce vs tardif). Les taurillons à l’auge avaient une croissance plus rapide, des poids de carcasse plus élevés, ainsi que des carcasses plus grasses. Nous avons observé qu’abattre plus tardivement au pâturage (17 et 21 mois vs 14 et 17 mois à l’auge), permettait d’atteindre des poids finaux similaires à ceux obtenus à l’auge et des carcasses de meilleure qualité, plus riche en muscle. Nous avons expliqué la majorité de nos résultats par les effets combinés des modes de conduite et de l’alimentation et avons voulu étudier leurs effets respectifs. Dans un second temps, l’étude des effets du mode de conduite a été faite dans un premier temps, par le biais d’une méta-analyse. Les performances des animaux à l’auge étaient meilleures qu’au pâturage, mais ces effets dépendaient de la stratégie de complémentation. De cette méta-analyse est également apparu le manque d’études auge vs pâturage sur l’alimentation et à ration égale. Afin d’étudier les effets respectifs du mode de conduite et de la stratégie de complémentation, un dispositif analytique avec des taurillons élevés à l’auge et au pâturage complémentés ou non avec du concentré a été mis en place. Dans un premier temps, une étude méthodologique menée grâce à ce dispositif nous a permis d’identifier que la SPIR permettait la meilleure estimation de la dMO, l’OMI et la MODI au pâturage. Les résultats de l’étude analytique ont montré que les animaux au pâturage utilisaient mieux leur alimentation pour leur croît que ceux à l’auge et la stratégie de complémentation influençait davantage ces variables que le mode de conduite. Avec une stratégie de complémentation appropriée, les animaux au pâturage peuvent atteindre des performances similaires à celles obtenues à l’auge. / Grazing, main way of feeding ruminants in the tropics, is often undervalued because it is associated with animal performance deemed insufficient, and may have adverse effects on the environment. Even if stall feeding allows better production, this way of feeding has drawbacks in terms of investment, profitability, impact of emissions on the environment and product quality. Intensification of grazing seems a way forward, but requires a better understanding of this way of feeding and its impact on feeding and animal performance. It also appears necessary to compare grazing and stalls feeding on homogeneous criteria, separating the components of these modes of management.The aim of the thesis is to evaluate and compare stalls and pasture feeding environment, taking into account also the distribution or not of concentrate on feeding, growth, slaughter characteristics and water consumption. At first , we studied in an experiment , the effects of these two feeding systems on growth, slaughter and carcass characteristics of Creoles bulls slaughtered at two ages (early vs. late ). Bulls fed in trough grew faster, had greater carcass weight and fatter carcasses. We observed that a later slaughter of grazing animals (17 and 21 months vs. 14 and 17 months in stalls), allowed to reach final weights similar to those obtained in stalls and carcasses richer in muscle. We explained most of our results by the combined effects of feeding environment and complementation strategy and wanted to study their effects. In a second step, the study of the effects of feeding environment was made in first instance, through a meta-analysis. Stalls fed animals had greater performances than pasture fed ones, but these effects depended on complementation strategy. This meta-analysis also highlighted the lack of knowledge on intake and digestibility at pasture, which is a limitation on attempts to compare with measurements carried out in trough-fed animals. To investigate the relative effects of feeding environment and complementation strategy, we conceived an analytical trial with Creole bulls reared in stalls and at pasture, supplemented or not with concentrate. First of all, this analytical trial was the support of a methodological study, which identified that the NIRS method allows the best estimate of the OMD, OMI and DOMI at pasture. The analytical trial showed that grazing animals had better feed efficiency feed for their growth than stall fed ones and complementation strategy influenced more these variables than feeding environment. With an appropriate strategy for complementation, grazing animals can achieve similar performance to those obtained at the trough.

La gestion des sites et sols pollués repose sur l’évaluation des expositions aux contaminants. Le retour d’expérience montre que les voies d’exposition directe, et notamment l’ingestion de terre pour les enfants, engendrent les niveaux de risque les plus élevés. Actuellement, en se basant sur la concentration totale d’un polluant dans le sol, l’évaluation des risques tend à être surprotectrice dans la mesure où seule une fraction de la substance peut pénétrer à l’intérieur de l’organisme. L’objectif de l’étude est de mettre en évidence que le test in vitro UBM (Unified Barge Method) de bioaccessibilité est pertinent pour estimer la fraction biodisponible des ETM dans les sols. Pour cela, il est nécessaire de démontrer que la solubilisation des contaminants dans le tractus gastro-intestinal est une étape limitante dans le processus de biodisponibilité et d’autre part que les mesures de bioaccessibilité sont corrélées aux mesures de biodisponibilité. Pour 15 sols sélectionnés sur trois sites contaminés différents, l’étude montre que la biodisponibilité est très variable pour le plomb (8% à 82%), le cadmium (12% à 91%) et l’arsenic (3% à 78%). Pour l’antimoine, les valeurs de biodisponibilité relative et de bioaccessibilité sont très faibles indépendamment des caractéristiques contrastées des sols (valeurs < 20%). De ce fait, ces conditions ne permettent pas de valider le test in vitro pour l’antimoine. Les résultats des corrélations, pour les trois autres contaminants, démontrent que la bioaccessibilité est l’étape limitante de la biodisponibilité et que le test UBM est pertinent pour estimer la bioaccessibilité de ces éléments dans les sols. Notre étude met également en évidence l’impact de la matrice sol sur les variations des valeurs de bioaccessibilité. Ainsi, il a été montré que la distribution des contaminants sur les différentes phases porteuses du sol est un paramètre majeur et robuste pour expliquer les variations de la bioaccessibilité pour l’ensemble des sols étudiés. Les résultats de l’étude mettent en lumière que le test in vitro UBM peut fournir une alternative possible aux investigations in vivo afin d’affiner les niveaux d’exposition des ETM suite à l’ingestion de sol / The management of contaminated soil is based on the assessment of exposure of pollutants. The review shows that the direct routes of exposure, including soil ingestion for children, generate the highest risk levels. Currently, based on the total pollutant concentration in soil, risk assessment tends to be overestimate because only a fraction of the substance may penetrate into the body. The aim of the study is to demonstrate that in vitro UBM test (Unified Method Barge) is relevant to estimate the bioavailable fraction of metals in the soil by estimating the bioaccessible fraction. For this, it is necessary to show that the solubilization of contaminants in the gastrointestinal tract is a limiting step in oral bioavailability process and that bioaccessibility is correlated to bioavailability. For 15 soils selected on three different sites, the study shows that bioavailability is highly variable for lead (8% to 82%), cadmium (12% to 91%) and arsenic (3 % to 78%). For antimony, the relative bioavailability and bioaccessibility values are very low independently of the different soil characteristics (values <20%). Thus, these conditions do not allow to validate in vitro test for antimony. The results of correlations, for the three other contaminants, show that bioaccessibility is the limiting step in the bioavailability process and that UBM test is relevant to estimate the bioaccessibility. Our study also highlights the impact of the soil matrix on the variation of bioaccessibility values. Thus, it was shown that the distribution of contaminants in the different bearing phases of soil is a major and robust parameter to explain the variations of bioaccessibility for all soils studied. The results of the study highlight that the in vitro UBM test is a promising alternative to in vivo investigations to measure the exposure levels of metals after soil ingestion

No description available.

Olestra is, a sucrose polyester, a noncaloric fat substitute, made from sucrose and several fatty acid esters. It has been approved by the FDA as a food additive used in preparing low-fat deep-frying foods such as savory snacks. Available literature on olestra was evaluated that had both positive and negative connotations. Clinical trials in numerous species of animals including humans were conducted to determine if olestra would affect the utilization and absorption of macro- and micronutrients; the effects of olestra on growth, reproduction, or its toxicity were also examined. The roles of olestra as a fat substitute, how it could effect on humans and the environment, and the potential impacts from its use in large amounts were assessed. Olestra can be removed from the environment by aerobic bacteria and fungi which may be isolated from activated sludge and soils.

Thesis advisor: Alan Richardson / Burgeoning exotic consumerism in the eighteenth century supplied British consumers with an increasingly material “Orient,” which never seemed so accessible as when it could be physically consumed, in the form of exotic groceries or ingestible substances like opium. My dissertation investigates how the linguistic representation of foreign, ingestible substances – which I call “exotic ingestants” – problematizes such attempts to access or master the Orient by underscoring the gap between literary trope and material thing. In the writings of Oliver Goldsmith, Thomas Moore, Charlotte Brontë, Charles Dickens, and others, exotic ingestion provides a flexible figure through which British authors do not just imagine the Orient, but also critically diagnose the ways in which that Orient functions as a cipher for domestic fears and fantasies. Their texts self-consciously highlight how both consumer practices and discursive representations fetishize, appropriate, or otherwise distort the Oriental “other” in question. A self-reflexive discursive mode, however, does not imply a consistently anti-imperial agenda. The authors in this study interrogate cultural binaries for a range of purposes, but what does remain consistent is that they do so in order to construct, renovate, or re-imagine their own sense of self. Going beyond the models of contamination or domestication that critics usually deploy when considering cultural representations of opium and tea, I investigate scenes of exotic ingestion as dynamic sites of identity formation, where British authors negotiate their national and transnational subjectivities by consciously engaging with constructions of cultural otherness. Each chapter compares two authors to spotlight one distinctive mode of cross-cultural imagination, and the way it plays out through figurations of exotic ingestion. Together, the four chapters trace a historical trajectory. The evolving scene of exotic ingestion offers an exemplary window into Britain’s construction of its own imperial identity, which develops in response to historical events such as the eighteenth-century consumer revolution, the 1851 Great Exhibition, and the Opium Wars with China. The prominently consumerist mode of British imaginations of China explains that rival empire’s particular, though not exclusive, significance to this project. Treating China as a case study but contextualizing it within both Sino-British relations and the Orientalist discursive tradition that emerged out of Britain’s reception of the Arabian Nights, this dissertation contributes to ongoing efforts at relocating British consciousness at the intersection of national, imperial, and global discourses and practices.

Made available in DSpace on 2014-06-11T19:22:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-08-18Bitstream added on 2014-06-13T19:27:12Z : No. of bitstreams: 1 bustamante_tf_me_botfm.pdf: 3625249 bytes, checksum: 92a758c187e8eec63582c316baef9e88 (MD5) / Universidade Estadual Paulista (UNESP) / A ingestão acidental de substâncias cáusticas constitui um grave problema de saúde pública, ocorrendo principalmente na faixa etária pediátrica, sendo a estenose do esôfago uma complicação frequente. A dilatação esofágica é o tratamento de escolha para estes casos. Várias substâncias já foram testadas nos casos refratários à dilatação, porém com resultados insatisfatórios. A mitomicina C, agente quimioterápico capaz de inibir a síntese protéica e a proliferação de fibroblastos, tem sido usada com sucesso em estenoses esofágicas refratárias às dilatações. No entanto, há poucos estudos experimentais descrevendo como a mitomicina C interage com o tecido lesado e qual o melhor momento para o seu uso após a lesão cáustica. Avaliar os efeitos do uso tópico da mitomicina C, associada ou não à dilatação esofágica, aplicada em diferentes momentos após a lesão cáustica do esôfago de ratos com soda cáustica (NAOH 10%). Para efeito de comparação, utilizou-se ratos nos quais se infundiu solução salina (SF0,9%) no esôfago. Quarenta e oito ratos foram divididos em 6 grupos com 8 ratos cada: grupo manipulado ou sham (Gs), grupo controle (Gc), grupo com lesão cáustica e não tratado (Gnt), grupo com lesão cáustica e aplicação de mitomicina C (MMC) logo após a lesão (GmmcD0), grupo com lesão cáustica e aplicação de MMC 14 dias após a lesão (GmmcD14) e grupo com lesão cáustica seguido de dilatação e aplicação de MMC 14 dias após a lesão (Gdil+mmcD14). A lesão cáustica foi produzida seguindo o modelo descrito por Gehanno & Guedon modificado pelo nosso grupo de pesquisa, com NaOH10%. Em 4 momentos de avaliação (7º, 14º, 21º, e 28º dias de pós operatório - PO), todos os animais foram pesados. No 7º e 21º dias de PO, 4 ratos de cada grupo foram submetidos ao exame contrastado de esôfago. No 28º dia de PO... / The accidental ingestion of caustic substances is an important problem of public health, occurring mainly in childhood. The esophageal stricture is a frequent complication and esophageal dilation is the treatment of choice. Many agents have been tested when esophageal dilation is unsatisfactory, although with poor results. Mitomycin C, a chemotherapeutic agent that inhibits protein synthesis and the proliferation of fibroblasts, has been used successfully in cases of esophageal stricture that are refractory to dilation. However, there are few experimental studies describing how this substance interacts with damaged tissue and the best time window for its use after caustic injury. The purpose of this study was to evaluate the effects of the topical application of MMC in rats, with or without associated esophageal dilatation, at different moments after the induction of a caustic esophageal lesion by NaOH10%. 48 Wistar rats were divided into 6 groups of 8 animals each: sham group (SG), control group (CG), injured group but not treated (NTG), injured group with mitomycin C application immediately after the caustic lesion (MMCD0G), injured group with MMC application 14 days after induction of caustic lesion (MMCD14G) and injured group with esophageal dilation and application 14 days after caustic lesion (MMCD14+DILG). The caustic injury was produced as described by Gehanno & Guedon, modified by our group, with NaOH10%. There were 4 moments of evaluation: 7°, 14°, 21° and 28° days after caustic injury, when rats were weighted. At 7° and 21° days after injury, it was performed the esophagograms of 4 rats of each group. On day 28 after caustic injury, all animals were sacrificed, and morphological and histopathological analyses were performed on the esophageal specimens, besides... (Complete abstract click electronic access below)

This thesis argues that caffeine use offered a survival advantage to our ancestors and that moderate use continues to offer modern humans benefits. Caffeine ingestion, through the blocking of adenosine receptors, elicits broad elements of the mammalian threat response, specifically from the ‘flight or fight’ and ‘tend and befriend’ repertoires of behaviour: in effect, caffeine hijacks elements of the stress response. If the effects of caffeine had been discovered recently, rather than being available to Homo sapiens since Neolithic hunter gatherer times, it is likely that caffeine would be considered a ‘smart’ drug. More caffeine is being ingested today than ever previously recorded. Caffeine use is found across all age groups, all socio-economic strata, most ethnic groups, and is being used increasingly by the medical and pharmaceutical industries and by the armed forces. Yet despite this wide usage and a substantial body of research literature, there is at present no clear pattern or plausible model for the way caffeine achieves its effects. There is much contradiction in the literature and ambiguity as to why caffeine use should improve performance on some tasks, impair it on others and have no effect on other tasks, for some but not all of the time. The present work argues, through an examination of the specificity of caffeine’s operation, that these effects are not arbitrary but elicited by the nature of the tasks, in particular that caffeine ingestion affects those processes and behaviours which improve the probability of survival under perceived threat or stress. This is argued through the perspective of evolutionary psychology and relies theoretically on Polyvagal Theory. The argument generates testable hypotheses and empirical support for the thesis is garnered from nine experiments on card-sorting, verbal and numerical processing, local and global categorization, field dependence-independence, the Stroop task, tests of visuo-spatial ability, and from a correlational study of caffeine use and personality traits. It is concluded that moderate caffeine use in healthy adults promotes behaviours likely to be adaptive under perceived threat or stress. Limitations of both theory and empirical work and are discussed, together with potential practical applications and suggestions for further work.