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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
261

Estudo geofísico em área contaminada por diesel no município de Cerquilho (SP) / Geophysical study in a diesel contaminated area in the municipality of Cerquilho (SP)

Junqueira, Paula Gomes [UNESP] 20 January 2017 (has links)
Submitted by Paula Gomes Junqueira null (pgjunqueira@hotmail.com) on 2017-03-13T06:01:46Z No. of bitstreams: 1 DefesaFinal.pdf: 5051274 bytes, checksum: 6ffce5e28d13b1d24dc4d4fe3898f485 (MD5) / Approved for entry into archive by LUIZA DE MENEZES ROMANETTO (luizamenezes@reitoria.unesp.br) on 2017-03-15T19:43:26Z (GMT) No. of bitstreams: 1 junqueira_pg_me_bauru.pdf: 5051274 bytes, checksum: 6ffce5e28d13b1d24dc4d4fe3898f485 (MD5) / Made available in DSpace on 2017-03-15T19:43:26Z (GMT). No. of bitstreams: 1 junqueira_pg_me_bauru.pdf: 5051274 bytes, checksum: 6ffce5e28d13b1d24dc4d4fe3898f485 (MD5) Previous issue date: 2017-01-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Impactos relacionados ao aporte de hidrocarbonetos em subsuperfície são particularmente preocupantes ao ambiente e à saúde humana, devido à aspectos degradativos e separação em fases dissolvida e residual, que resultam num tempo frequentemente prolongado de residência. Estudos da fase residual são relevantes ao monitoramento e remediação de contaminações em subsuperfície, frente à possibilidade de contaminação das águas subterrâneas mesmo após anos da seção da fonte primária. Os métodos geofísicos são ferramentas consagradas no estudo de contaminações em solo, tanto na fase de confirmação, como na fase de monitoramento, devido à possibilidade de investigações indiretas e não invasivas em solos e rochas. A integração de dados geofísicos com análises químicas de solo ou águas subterrâneas proporciona uma visão abrangente e adequada ao estudo e monitoramento de áreas contaminadas. Neste sentido, este trabalho apresenta o estudo geofísico numa área impactada pelo vazamento de hidrocarbonetos, devido a acidente ferroviário. A área investigada é um trecho de ferrovia localizado no município de Cerquilho (SP), onde ocorreu em 2002 um acidente com vagões que transportavam óleo diesel e está em processo de recuperação desde então. Foram medidos e calculados os parâmetros físicos resistividade elétrica e cargabilidade a partir dos métodos geofísicos Eletrorresistividade e Polarização Induzida, por meio da técnica de Imageamento Elétrico. Também foram compilados dados de análises químicas realizadas na área de estudos e disponibilizados pela CETESB. A análise dos resultados permitiu determinar que os métodos geofísicos foram sensíveis aos contaminantes presente na área de estudos e delimitar fase residual e dissolvida e zonas da pluma de contaminação. / Impacts related to the oil supply in the subsurface are of particular concern to the environment and human health due to degradative aspects and separation in dissolved and residual phases, resulting in an often prolonged residence time. Residual phase studies are relevant to monitoring and remediation of contaminants in the subsurface, facing the possibility of groundwater contamination even after years of primary source section. Geophysical methods are tools appropriate to the study of contamination in soil, both in the confirmation phase, as in the monitoring phase, due to the possibility of indirect and non-invasive investigations in soils and rocks. Integration of geophysical data with chemical analysis of soil or groundwater provides a comprehensive and adequate view to the study and monitoring of contaminated areas. In this sense, this work presents a geophysical study in an area affected by the leak of hydrocarbons due to railway accident. The study area is a railway stretch in the municipality of Cerquilho (SP), where an accident with wagons carrying diesel oil occurred in 2002 and the area is in recovery process since then. Electric resistivity and chargeability were the physical parameters measured from geophysical methods Electrical Resistivity and Induced Polarization by means of electrical imaging technique. Chemical analysis data collected in the study area were provided by CETESB and compiled. The results analysis allowed to determine that the geophysical methods were sensitive to the contaminants in the study area and delimit residual and dissolved phase and contamination plume features.
262

Estudo da porção offshore da bacia do Benin e o seu potencial no armazenamento de hidrocarbonetos, margem equatorial africana /

Benvenutti, Carlos Felipe. January 2012 (has links)
Resumo: A presente pesquisa conta com uma área de estudo de 7.737 km2 na porção ojJshore da Bacia do Benin, localizada na Província do Golfo da Guiné, Margem Equatorial Africana, onde a lâmina da água varia de 100 a mais de 3.200 m, cobrindo basicamente o talude. Dados ísmicos 3D e 2D foram disponibilizados pela Compagnie Béninoise des Hydrocarbures(CBH SARL) para interpretação dos mesmos com o objetivo de caracterizar o arcabouço estrutural e estratigráfico da região, assim como avaliar o potencial do armazenamento de hidrocarboneto. Foi necessário o mapeamento dos horizontes sísmicos, a elaboração de mapas de contorno estrutural, de atributos sísmicos e de isópacas. A Bacia do Benin encontra-se entre as zonas de fratura de Romanche e Chain, correlata à Bacia do Ceará na Margem Equatorial Brasileira. Sua evolução tectono-sedimentar está condicionada à ruptura do Gondwana no Cretáceo Inferior, predominando estruturas da fase rifte relacionadas à distensão e transcorrência, a influência da transpressão é muito significativa no Cretáceo Superior. Destaca-se também uma tectônica gravitacional marcada por falhamentos dos níveis estratigráficos cenozóicos. A coluna sedimentar é representada por uma seção rifte continental limitada pela discordância do Meso-Albiano e outra pós-rifte marinha, do Albiano Superior ao Recente; sendo esta subdividida pela discordância do Oligoceno relacionada a uma queda eustática. A sedimentação está controlada pelo strends NE-SW e ENE-WSW, incluindo os canais submarinos. Os principais altos estruturais desta região já foram perfurados sem sucesso comercial, porém o potencial de acumulação de hidrocarbonetos é promissor, pelo menos dois grandes canais foram identificados no estudo em uma região cuja profundidade do fundo do mar é cerca de 2.200 m. Oportunidades... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The present research has a study area of 7.737 km2 located in the offshore portion of Benin Basin in the Gulf of Guinea Province, African Equatorial Margin. The water depth ranges from 100 to more than 3.200 m, basically covering the slope. The Compagnie Béninoise des Hydrocarbures (CBH SARL) provided 3D and 2D seismic data in order to interpret and characterize the stratigraphic and structural frarnework, as well as to evaluate the petroleum exploration potential. To achieve the desired results, it was performed seismic horizons mapping, elaboration of structural outline, isopach and seismic attribute maps. Benin Basin is limited by Romanche and Chain fracture zones and is correlated to Ceará Basin in Brazilian Equatorial Margin. Its tectono-stratigraphic evolution was conditioned by the Gondwana break-up in the Lower Cretaceous and shows rift structures related to extension trike-slip tectonics. The transpression influence is very significant in the Upper Cretaceous. It is also highlighted a gravitational tectonic marked by normal faults in the Cenozoic level. The sedimentary package is represented by a continental rift section limited by a Mid-Albian unconformity and other marine post-rift sequence from Upper Albian to Recent; the last one can still be divided by the Oligocene unconformity. The sedimentation is controlled by NE-SW and ENE- WSW trends, including submarine channels in the Upper Cretaceous. The main structural traps weredrilled in the study area without commercial success. At least two great channels were identified in a region where the water depth is around 2.200 m. Roll-overs and minor channels opportunities in Paleogene and Neogene should also be considered. The pre-rift sequences of the study area are poorly recognized, the absence of well information in this interval and the low resolution of seismic data... (Complete abstract click electronic access below) / Orientador: Nelson Angeli / Coorientador: Maria Gabriela C. Vincetelli / Banca: George Luiz Luvizotto / Banca: Adilson Viana Soares Júnior / Mestre
263

Exploring the role and the function of Aryl Hydrocarbon Receptor (AhR) and Aryl Hydrocarbon Nuclear Translocator (ARNT) in T cells

Rosenzweig, Ella January 2012 (has links)
The Aryl Hydrocarbon Receptor (AhR) and the Aryl Hydrocarbon Nuclear Translocator (ARNT) play a role in mediating transcriptional responses to environmental pollutants, including the highly toxic compound 2,3,7,8-tetrachlorodibenzo -p-dioxin (TCDD) but also endogenous physiological ligands. More recent studies have also indicated that the AhR plays a role in the immune system notably in effector Th17 cells where it seems to be critical for the production of the IL-22 cytokine. It is known that AhR ligands such as dioxins can suppress CD8 T cell mediated antiviral immune responses but it is not known whether this reflects a direct role of the AhR in CD8 T cells.Accordingly, one objective of the present study was to explore AhR and ARNT expression in CD8 T cells. The initial strategy was to probe AhR and ARNT expression by western blot analysis. A second approach was to develop a mouse model that would fate mark single lymphocytes that have activated AhR signaling pathways. A third strategy was to examine the impact of deletion of AhR and ARNT on CD8 T-cell function.The data show that AhR and ARNT expression in CD8 T cells is limited to immune activated effector cells and these transcription factors are not expressed in naïve CD8 T cells. There are only low levels of AhR complexes in conventional CD8 positive cytotoxic T cells. To investigate AhR function at the single cell level we developed a mouse model to fate mark cells that have activated AhR signaling. In this model a mouse expressing Cre recombinase ‘knocked in’ to the CYP1A locus (CYP1A1Cre+/-) was backcrossed to the R26REYFP reporter mouse. In R26REYFP mice, a gene encoding EYFP is knocked into the ubiquitously expressed Rosa26 locus preceded by a loxP flanked stop sequence. CYP1A1 expression is controlled by AhR/ARNT complexes and the concept of our model was that cells that express AhR and ARNT complexes and are triggered with AhR ligands will express Cre recombinase and delete the loxP flanked stop sequence in the R26REYFP reporter locus and hence begin to express YFP.In vitro experiments demonstrated the validity of this AhR reporter model. The in vitro data reveal that expression of functional AhR/ARNT complexes occurs during Th17 and Tc17 cell differentiation but only a very low frequency of cytotoxic T cells activates the AhR. In vivo data found no evidence for AhR activation during T cell development in the thymus but show strong evidence for activation of AhR/ARNT signaling in innate lymphocytes in the gut. The ARNT transcription factor is highly expressed in cytotoxic T cells. These cells do not express functional AhR complexes, yet we considered that ARNT might play a role in CD8 T cell biology because of its ability to dimerise with the transcription factor Hif-1a. Our studies of T cells lacking ARNT expression revealed that in CD4 T cells the ARNT transcription factor regulates IL-17 and IL-22 production. In CD8 T cells we discovered that Hif-1a/ARNT signaling controls glycolysis in immune activated cells by sustaining expression of glucose transporters and multiple rate limiting glycolytic enzymes. ARNT was not required for CD8 T cell proliferation but was required for immune activated CD8 T cells to normally differentiate to express perforin and granzymes and to acquire the migratory program of effector T cells. Importantly, we discovered that Hif-1a/ARNT signaling is regulated by mTOR (mammalian target of rapamycin) thus revealing a fundamental mechanism linking nutrient sensing and transcriptional control of CD8 T-cell differentiation.
264

Ethane Conversion to Ethylene in a Direct Hydrocarbon Fuel Cell

Wurtele, Matthew 15 February 2019 (has links)
Direct hydrocarbon fuel cells are fuel cells than use hydrocarbons directly as fuel instead of the most commonly used fuel in a fuel cell, hydrogen. Studies are being done on direct hydrocarbon fuel cells because they have the potential to be energetically more efficient than hydrogen fuel cells. There are many different hydrocarbons that are available to use as a feed stock and each one reacts at different reaction rates. As the current density of a fuel cell is linked to the reaction rate, it is important to know the energetics of an oxidation reaction that is occurring. Density Functional Theory (DFT) is a technique that can be used to predict the energy states of intermediate reaction steps in a given mechanism. The focus of this study is the using DFT to explore the energetics of the oxidation of ethane to ethylene in a nickel-anode catalyst fuel cell. DFT was used in adsorption runs to optimize the geometries beginning (adsorbed ethane) and end (adsorbed ethylene) of the oxidation reaction. DFT was then used to calculate the energy of transition states by varying bond lengths. It was determined the removal of the second hydrogen from the ethyl radical is the most energy intensive step and, thus, the rate limiting step. Hydrogen, ethane, and ethylene were all explored in this study. The heats of adsorption varied from largest to smallest in the order of ethylene, hydrogen, and ethane. It was determined that the heat of adsorption of hydrogen is sufficient to meet the energy requirements for the dissociation reaction. This may help explain why hydrogen reacts so readily in fuel cells. Conversely, the heats of adsorption for the hydrocarbons did not meet the energy requirements for the dissociation reactions. This may help explain why ethane and ethylene react more slowly in a fuel cell as compared to hydrogen. Also, the oxidation of ethane to ethylene requires two large activation energies. These two additional activation energies may help explain why ethylene reacts more readily than ethane in a fuel cell.
265

Anthropogenic secondary organic aerosol from aromatic hydrocarbons

Al-Naiema, Ibrahim Mohammed Jasim 01 May 2018 (has links)
Atmospheric aerosols deteriorate visibility and pose a significant risk to human health. The global fluxes of secondary organic aerosols (SOA) that form in the atmosphere from aromatic hydrocarbons are poorly constrained and highly uncertain. The lack of molecular tracers to quantify anthropogenic SOA (ASOA) in part limits the understanding of its abundance and variability, and results in a systematic underestimation of the role of ASOA in the atmosphere. The research presented in this thesis advances the knowledge about ASOA through the i) development of new and advanced methods to quantify potential ASOA tracers, ii) evaluation of their suitability as tracers for ASOA, and iii) application of the validated tracers to assess the spatial, diurnal and seasonal variation of ASOA in three urban environments. In this research, a greater understanding of the role of ASOA is gained through the expansion of tracers for SOA from aromatic hydrocarbons. An analytical method to quantify furandiones, which are produced in high yields from the photooxidation of aromatic hydrocarbons, was developed and enabled the first ambient measurements of furandiones. The optimized method allows for the simultaneous extraction of primary source tracers (e.g., polycyclic aromatic hydrocarbons, hopanes, levoglucosan) and other potential ASOA tracers (e.g., 2,3-dihydroxy-4-oxopentanoic acid [DHOPA], benzene dicarboxylic acids, and nitromonoaromatics). The systematic evaluation of potential ASOA tracers by their detectability, gas-particle partitioning, and specificity revealed that DHOPA, phthalic acid, 4-methylphthalic acids, and some nitromonoaromatics are good ASOA tracers because they are specific to aromatic hydrocarbon photooxidation, readily detected in ambient air, and substantially partition to the particle phase under ambient conditions. These tracers are thus recommended for use in field studies to estimate ASOA contributions to atmospheric aerosol relative to other sources. ASOA was determined to be a significant contributor to PM2.5 organic carbon (OC) in three urban environments. In the industrial Houston Ship Channel area in Houston, TX, ASOA contributed 28% of OC, while biogenic SOA (BSOA) contributed 11%. Diurnally, ASOA peaked during daytime and was largely associated with motor vehicle emissions. In Shenzhen, a megacity in China, 13-23% of OC mass was attributed to ASOA, three folds higher than BSOA. When China controlled the emissions from fossil fuel-related sources, the ASOA contribution to OC reduced by 42-75% and visibility remarkably improved. In downtown Atlanta, GA, ASOA contributed 29% and 16% of OC during summer and winter, respectively. ASOA dominates over BSOA during winter, while high biogenic VOC fluxes made BSOA the major SOA source in Atlanta, GA during summertime. These results indicate the high abundance of ASOA in urban air that has potential to be reduced by modification of anthropogenic activities. Overall, the work presented in this dissertation advances the knowledge about the abundance and variation of ASOA in urban atmospheres through the development of quantification methods and expansion of ASOA tracers. These tracers improve source apportionment of ASOA in receptor based models, which can ultimately aid in developing and implementing effective strategies for air quality management.
266

Regulatory crosstalk and interference between the PCB 126 stimulated AHR and hypoxia stimulated HIF-1α signaling pathways

Vorrink, Sabine Ulrike 01 May 2014 (has links)
Polychlorinated biphenyls (PCBs) are synthetic organic chemicals that persist in the environment and are known to be carcinogenic to humans. Virtually all of the deleterious effects of PCB 126, the most potent dioxin-like PCB, are mediated by the aryl hydrocarbon receptor (AhR). By means of the common cofactor ARNT, the AhR signaling pathway can crosstalk with the hypoxia signaling pathway. Regulated by hypoxia-inducible factors (HIFs), the hypoxia pathway mediates responses to environments of reduced oxygen availability (hypoxia). This dissertation specifically examines the crosstalk and interference between these two pathways in the context of PCB 126 exposure. The results of this dissertation show that the antagonistic relationship between the AhR and hypoxia signaling pathways affects the function and responses of both AhR and HIF-1Α. We provide substantial evidence that ARNT is indeed a crucial factor in both the AhR and HIF-1Α signaling pathways. Furthermore, this dissertation examines regulatory mechanisms involved in AhR-mediated gene expression and identifies epigenetic regulation as a critical factor in AhR target gene expression. In summary, this dissertation helped to improve the understanding of mechanisms of PCB 126 toxicity. Understanding the detrimental biological effects of these ubiquitous environmental pollutants might ultimately have significant implications for human health.
267

Economic Diversification in Saudi Arabia: Looking Beyond Oil

Kleemeier, Dena 01 January 2019 (has links)
Saudi Arabia faces a universally acknowledged need to diversify beyond hydrocarbons. The Saudi Arabian government has outlined a strategy to achieve diversification through its Vision 2030 reform plan. Contrary to the Vision 2030 plan, the Saudi government should allow for entrepreneurs and market signals to determine diversification when considering what sectors should receive investment, with the exception of broad infrastructure investments contributing to the overall enabling environment. Government lending for private-sector investments need to have plausibly high projected rates of return, and meet minimum standards of environmental and social responsibility, requiring participation by multiple government ministries sufficiently insulated from the government.
268

Non-Methane Hydrocarbon Source Apportionment and BTEX Risk Assessment of Winter 2015 in Roosevelt, Utah

Lamb, Jerimiah 01 December 2017 (has links)
Non-Methane Hydrocarbons (NMHC) monitored in Roosevelt Utah including Benzene, Toluene, Ethylbenzene and Xylene (collectively known as BTEX) are associated with deleterious effects including cancer. This study was designed to assess the origin and effect of the toxicants and addressed two points: 1) Source identification using the USEPA’s Positive Matrix Factorization (PMF) and NOAA’s Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model and 2) A human health risk assessment based on ambient concentrations of BTEX collected at the Roosevelt site. Model fit indicated that the primary contributor to total NMHCs was local oil and gas operations and was supported by previous assessments. Assessment of ambient BTEX concentrations was associated with slightly elevated carcinogenic risk.
269

Characterisation and modelling of naturally fractured reservoirs

Tran, Nam Hong, Petroleum Engineering, Faculty of Engineering, UNSW January 2004 (has links)
Naturally fractured reservoirs are generally extremely complex. The aim of characterisation and modelling of such reservoirs is to construct numerical models of rock and fractures, preparing input data for reliable stimulation and fluid flow simulation analyses. This requires the knowledge of different fracture heterogeneities and their correlations at well locations and inter-well regions. This study addresses the issues of how to integrate different information from various field data sources and construct comprehensive discrete fracture networks for naturally fractured reservoir. The methodology combines several mathematical and artificial intelligent techniques, which include statistics, geostatistics, fuzzy neural network, stochastic simulation and simulated annealing global optimisation. The study has contributed to knowledge in characterisation and modelling of naturally fractured reservoirs in several ways. It has developed: .An effective and data-dependant fracture characterisation procedure. It examines all the conventional reservoir data sources and their roles towards characterisation of different fracture properties. The procedure has the advantage of being both comprehensive and flexible. It is able to integrate all multi-scaled and diverse fracture information from the different data sources. .An improved hybrid stochastic generation algorithm for modelling discrete fracture networks. The stochastic simulation is able to utilise both discrete and continuum fracture information. It could simulate not only complicated distributions for fracture properties (e.g. multimodal circular statistics and non-parametric distributions) but also their correlations. In addition, with the incorporation of artificial fuzzy neural simulation, discrete multifractal geometry of fracture size and fracture density distribution map could be evaluated and modelled. Compared to most of the previous fracture modelling approach, this model is more flexible and comprehensive. .An improved conditional global optimisation model for modelling discrete fracture networks. The hybrid model takes full advantages of the advanced fracture characterisation using geostatistical and fuzzy neural analyses. Discrete fractures are treated individually and yet continuum information could be modelled. Compared to the stochastic simulation approach, this model produces more representative fracture networks. Compared to the conventional optimisation programs, this model is more versatile and contains superior objective function.
270

Calculation of the effective permeability and simulation of fluid flow in naturally fractured reservoirs

Teimoori Sangani, Ahmad, Petroleum Engineering, Faculty of Engineering, UNSW January 2005 (has links)
This thesis is aimed to calculate the effective permeability tensor and to simulate the fluid flow in naturally fractured reservoirs. This requires an understanding of the mechanisms of fluid flow in naturally fractured reservoirs and the detailed properties of individual fractures and matrix porous media. This study has been carried out to address the issues and difficulties faced by previous methods; to establish possible answers to minimise the difficulties; and hence, to improve the efficiency of reservoir simulation through the use of properties of individual fractures. The methodology used in this study combines several mathematical and numerical techniques like the boundary element method, periodic boundary conditions, and the control volume mixed finite element method. This study has contributed to knowledge in the calculation of the effective permeability and simulation of fluid flow in naturally fractured reservoirs through the development of two algorithms. The first algorithm calculates the effective permeability tensor by use of properties of arbitrary oriented fractures (location, size and orientation). It includes all multi-scaled fractures and considers the appropriate method of analysis for each type of fracture (short, medium and long). In this study a characterisation module which provides the detail information for individual fractures is incorporated. The effective permeability algorithm accounts for fluid flows in the matrix, between the matrix and the fracture and disconnected fractures on effective permeability. It also accounts for the properties of individual fractures in calculation of the effective permeability tensor. The second algorithm simulates flow of single-phase fluid in naturally fractured reservoirs by use of the effective permeability tensor. This algorithm takes full advantage of the control volume discretisation technique and the mixed finite element method in calculation of pressure and fluid flow velocity in each grid block. It accounts for the continuity of flux between the neighbouring blocks and has the advantage of calculation of fluid velocity and pressure, directly from a system of first order equations (Darcy???s law and conservation of mass???s law). The application of the effective permeability tensor in the second algorithm allows us the simulation of fluid flow in naturally fractured reservoirs with large number of multi-scale fractures. The fluid pressure and velocity distributions obtained from this study are important and can considered for further studies in hydraulic fracturing and production optimization of NFRs.

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