Thesis Ph. D.)(Chemical Engineering)--University of Pretoria, 2003. / Title from opening screen (viewed Oct. 06, 2004). Summaries in English and Afrikaans. Includes bibliographical references (leaves 144-151).

Thesis (Ph. D.)--University of Chicago, Dept. of Radiology, August 2000. / Includes bibliographical references. Also available on the Internet.

No description available.

Orientador: Paulo Sérgio de Moraes Barros / Banca: Carlos Augusto Araujo Valadão / Banca: Stélio Pacca Loureiro Luna / Banca: Denise Tabacchi Fantoni / Banca: Newton Nunes / Resumo: Os principais fatores a serem considerados durante a anestesia em eqüinos são a depressão cardiovascular e ventilatória e suas implicações hemodinâmicas. O objetivo do presente estudo foi o de avaliar duas modalidades ventilatórias na espécie eqüina e as repercussões destes modos de ventilação nos parâmetros ventilatórios, hemodinâmicos e mecânica respiratória. Foram utilizados 19 eqüinos clinicamente sadios, em decúbito lateral, aleatoriamente divididos em dois grupos, sendo que no Grupo I foi realizada a ventilação com pressão positiva intermitente e, no Grupo II com pressão controlada. O experimento foi dividido em duas fases, sendo que na primeira foram avaliados os parâmetros ventilatórios e de mecânica respiratória e, na segunda fase, além desses, também foram avaliados os parâmetros hemodinâmicos. Observou-se melhora dos parâmetros de ventilação em relação aos momentos de ventilação espontânea, quando empregou-se a ventilação controlada. Não foram observadas alterações hemodinâmicas e de oxigenação quando comparados os diferentes momentos num mesmo grupo, porém os valores da pressão venosa central e da pressão da artéria pulmonar foram superiores no grupo da ventilação com pressão positiva intermitente. Concluiu-se que não há diferença entre a ventilação com pressão positiva intermitente e a ventilação com pressão controlada em eqüinos clinicamente saudáveis. / Abstract: The most important factors to be considered in equine anesthesia are the cardiovascular and ventilatory depressions and further hemodynamic failure. The purpose of the present study was to evaluate two modes of mechanical ventilation in horses and their repercussion on ventilatory and hemodynamic parameters and respiratory mechanics also. Nineteen healthy horses in lateral recumbency, were randomly assigned into two groups. In Group I, intermittent positive pressure ventilation was used and, in Group II, pressure controlled ventilation. The experiment was divided into two phases, in the first ventilatory parameters and respiratory mechanics were evaluated and in the second phase, hemodynamic parameters were also measured. A significant improvement was observed in ventilatory parameters when compared controlled to spontaneous ventilation. No changes in hemodynamic and oxygenation parameters were observed, but central venous pressure and pulmonary arterial pressure were higher with intermittent positive pressure ventilation. In conclusion, there is no difference between intermittent positive pressure ventilation and pressure controlled ventilation in healthy horses. / Doutor

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / Devido à degradaÃÃo progressiva dos corpos hÃdricos em geral, tem-se dado bastante atenÃÃo a alternativas para a recuperaÃÃo da qualidade de suas Ãguas. TÃcnicas de aeraÃÃo e oxigenaÃÃo artificial via injeÃÃo de ar ou oxigÃnio puro na Ãgua (plumas de bolhas) podem ser utilizadas para tal finalidade. Nesse contexto, o presente trabalho desenvolveu um modelo integral para avaliaÃÃo da transferÃncia de massa de plumas de bolhas circulares em ambientes nÃo estratificados, o qual à baseado em uma distribuiÃÃo radial do tipo Gaussiana das propriedades do escoamento e em relaÃÃes matemÃticas para o coeficiente de entrada turbulenta e o fator de amplificaÃÃo da quantidade de movimento devido à turbulÃncia. O impacto da transferÃncia de massa na hidrodinÃmica de plumas de bolhas foi investigado considerando diferentes diÃmetros de bolha, vazÃes de gÃs e profundidades em sistemas de aeraÃÃo e oxigenaÃÃo. Os resultados revelaram impacto significativo quando bolhas finas sÃo consideradas mesmo em profundidades moderadas. Bolhas mÃdias apresentaram, em geral, comportamento semelhante ao de bolhas grossas. As simulaÃÃes tambÃm indicaram que, em condiÃÃes de vazÃes relativamente baixas e elevadas profundidades, dissoluÃÃo e turbulÃncia podem afetar a hidrodinÃmica da pluma de bolhas, o que demonstra a importÃncia de se levar o fator de amplificaÃÃo da quantidade de movimento em consideraÃÃo. SimulaÃÃes utilizando o modelo proposto e modelos clÃssicos disponÃveis na literatura resultaram em boa concordÃncia tanto para processos de aeraÃÃo quanto de oxigenaÃÃo. Finalmente, foram apresentados estudos de caso para os dois processos. / Due to the progressive degradation of water bodies in general, alternatives have been studied so as to restore their water quality. Artificial aeration/oxygenation by injecting air/pure oxygen in the water (bubble plumes) can be used for this purpose. Hence, this study presents an integral model to evaluate gas transfer from circular bubble plumes in unstratified environments which is based on a radial Gaussian type distribution of plume properties and functional relationships for the entrainment coefficient and factor of momentum amplification due to turbulence. The impact of gas-liquid mass transfer on bubble plume hydrodynamics is investigated considering different bubble sizes, gas flow rates and water depths. Also simulations were run for aeration and oxygenation systems in order to provide the analysis of these effects. The results revealed a significant impact when fine bubbles are considered, even for moderate water depths. Medium bubbles present overall similar behavior as coarse bubbles. Additionally, model simulations also indicate that for bubble plumes with relatively low gas flow rates and high water depths, both dissolution and turbulence can affect bubble plume hydrodynamics, which demonstrates the importance of taking the momentum amplification factor relationship into account. For deeper water conditions, simulations of bubble dissolution using the present model and classical models available in the literature resulted in a very good agreement for both aeration and oxygenation processes. Finally, case studies involving those processes are presented.

Extracorporeal membrane oxygenation (ECMO) has been used as life-saving support for children with varying causes of respiratory and/or cardiac failure. However, few studies have assessed the utility of ECMO as a viable treatment option in the setting of pediatric burn injury. We aim to examine the outcomes of pediatric burn patients requiring ECMO support by utilizing the Extracorporeal Life Support Organization (ELSO) registry in order to elucidate whether or not ECMO should be considered in this population. A retrospective cohort study was conducted by querying the ELSO database for all pediatric patients (birth to less than 18 years) who were supported on ECMO with burn-associated cardiopulmonary failure between 1990 and 2016. ICD-9 codes 940–949.5 were utilized to identify patients with an associated burn injury. Venovenous ECMO was defined as any patient with only venous cannulas, including double-lumen venous cannulas. Venoarterial ECMO was defined as any patient with a venous and an arterial cannula, any patient originally supported on VA ECMO that was converted to venovenous, or any patient originally supported on venovenous that was converted to venoarterial ECMO. Oxygenation indices (OI) and complication rates were compared among survivors and non-survivors for both venovenous (VV) and venoarterial (VA) groups. Primary outcome variables were survival and non-survival to hospital discharge. Demographic and clinical data, along with pre-ECMO variables and ECMO complications, were analyzed for predictive mortality. A total of 113 patients met inclusion criteria for the study. Overall survival to discharge was 52.2% (n=59) for the entire cohort. 73 patients were supported on VA ECMO, while 37 patients required VV ECMO support with a survival to discharge of 47.9% (n=35) and 62.2% (n=23), respectively. There was no statistical difference for median age (p=0.765), median weight (p=0.932), or median hours on ECMO (p=0.963) between survivors and non-survivors. Three patients did not have the type of cannulation identified but were listed as “other” in the ELSO registry. Patients requiring ECMO support for respiratory failure had a higher over-all survival (55.7%, n=97) compared to those requiring ECMO for cardiac failure (33.3%, n=6) or ECPR (30%, n=10). Patients who were supported on VV ECMO for respiratory failure had the best overall survival at 62.2% (n=37) and those cannulated to VA ECMO for respiratory failure had a survival of 51.7% (n=58). Patients supported on VA ECMO for cardiac failure or ECPR support had the same survival at 33.3% (n=6 and 9 respectively). Several factors were found to be significantly associated with mortality. Cardiac arrest prior to cannulation was associated with increased mortality with an odds ratio of 3.41 (95% CI 1.29-9.06, p=0.011). There was a trend for the use of nitric oxide prior to cannulation to be associated with a decrease in mortality with an odds ratio of 0.40 (95% CI 0.16-1.01, p=0.048)Following cannulation, complications including the need for inotropes (OR 2.64, 95% CI 1.24-5.65, p=0.011), presence of gastrointestinal hemorrhage (p=0.049), and hyperglycemia (glucose > 240mg/dL) (OR 3.42, 95% CI 1.13-10.38, p=0.024) were associated with increased mortality.

No description available.

No description available.

High gravity (HG) brewing has become the most used strategy for maximizing fermenter productivity in commercial brewing. While HG brewing has many benefits, the additional stress placed on the yeast due to the higher concentration of fermentable sugars in the wort can negatively impact fermentation performance and flavor compound formation. A proper dissolved oxygen (DO) level is vital to guarantee adequate yeast performance during HG fermentations. Dissolved oxygen is vital to yeast viability throughout the fermentation process, as yeast requires oxygen to synthesize vital cell membrane components needed for continued anaerobic growth and cell division. Previous research has demonstrated the importance of DO in wort for regular gravity fermentation and flavor compound production. However, the impact of dissolved oxygen during HG brewing on fermentation performance and how this will impact the production of flavor compounds have not been fully researched. The objectives of this research were to analyze the impact of wort aeration timing and concentration on fermentation performance, flavor stability, and the formation of volatile flavor compounds, determined using gas chromatography. Gas chromatography analysis was modeled after the ASBC Method Beer-48. Flavor stability and staling was analyzed during aging under normal and accelerated conditions utilizing TBA analysis. Pre-pitch oxygen treatments at levels greater than 8 ppm dissolved oxygen significantly increased attenuation when compared to the unoxygenated controls. Post-pitch oxygenation significantly increased attenuation, with DO treatments at levels of 8 ppm showed the most significant decrease in wort specific gravity. Aldehyde, ester, and higher alcohol production were all significantly affected by DO concentration. Aldehyde production decreased with increased DO concentration. Ester production increased from 0 to 8 ppm DO treatment and decreased at DO treatments greater than 8 ppm. Higher alcohol production increased from 0 to 10 ppm and decreased with DO treatments greater than 10 ppm. Greater concentrations v of DO resulted in greater TBA index values after normal and accelerated aging, with accelerated aging producing greater TBA index values than normal aging.

No description available.