Made available in DSpace on 2014-10-09T12:45:00Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:08Z (GMT). No. of bitstreams: 1 07181.pdf: 9427675 bytes, checksum: b63bf520f5e52b6456ed23681cc3e0dd (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:26:35Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:28Z (GMT). No. of bitstreams: 0 / Neste trabalho foram determinados experimentalmente os índices espectrais 28r* e 25d* e o fator de eficiência de contagem gama através da técnica de varredura gama de varetas combustíveis no reator nuclear IPEN/MB-01. A vantagem deste método experimental consiste no fato de terem sido eliminados a maioria dos fatores de correção advindos dos cálculos, permanecendo somente os fatores de rendimento médio de fissão e a fração de fissão no 235U na determinação do 25d*. Os experimentos foram efetuados com luvas de cádmio de diferentes espessuras: 0,55 mm, 1,10 mm e 2,20 mm. As incertezas experimentais inferiores a 1% e a excelente caracterização dos dados geométricos e materiais do reator IPEN/MB-01 permitem utilizar os resultados obtidos como benchmark para a validação de bibliotecas de dados nucleares. Sendo assim, foi utilizado o programa MCNP-5 com as bibliotecas de dados nucleares: ENDF/B-VI.8, ENDF/B-VII.0, JENDL-3.3 e JEFF-3.1. A comparação entre os valores advindos dos cálculos e os resultados experimentais mostrou que houve progressos sensíveis com as bibliotecas de dados nucleares atuais. Os desvios entre a comparação dos valores calculados e os resultados experimentais são inferiores a 2 %, sendo que o melhor desempenho foi obtido com a biblioteca de dados nucleares ENDF/B-VII.0 e a incerteza máxima na comparação dos resultados foi de -1,4 %, para as bibliotecas de dados nucleares JEFF-3.1 e JENDL-3.3. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:26:15Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:38Z (GMT). No. of bitstreams: 0 / Este trabalho apresenta um estudo da Física dos Sistemas dirigidos por Fontes Externas (ADS). É apresentada a definição de alguns parâmetros estáticos e cinéticos da Física do reator que são importantes na avaliação e definição destes sistemas. O objetivo é demonstrar que há diferenças nestes parâmetros quando o sistema está no nível crítico ou subcrítico. Além disso, o trabalho mostra as diferenças observadas nos parâmetros para diferentes modelos de cálculo. São mostradas nesta dissertação duas metodologias de cálculo: Gandini&Salvatores e Dulla e são calculados alguns destes parâmetros utilizando as duas metodologias. O código determinístico de transporte ANISN é utilizado no cálculo destes parâmetros. Numa configuração subcrítica do Reator IPEN/MB-01 dirigido por uma fonte externa de nêutrons são calculados alguns parâmetros físicos. No final do trabalho são apresentadas as conclusões obtidas através destes cálculos. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:34:24Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:44Z (GMT). No. of bitstreams: 0 / Este trabalho visa determinar as razões espectrais e o espectro de energia de nêutrons no interior do combustível do Reator Nuclear IPEN/MB-01. Estes parâmetros são de grande importância para determinar com precisão parâmetros físicos de reatores nucleares, como taxas de reação, tempo de vida do combustível e também parâmetros de segurança, tais como reatividade. Para o experimento, utilizou-se detectores de ativação na forma de finas folhas metálicas, introduzidas em uma vareta combustível experimental desmontável. Em seguida, a vareta foi colocada na posição central do núcleo, que tem uma configuração retangular padrão de 26x28 varetas combustível. Foram utilizados detectores de ativação de diferentes elementos como 197Au, 238U, 45SC, 58Ni, 24Mg, 47Ti e 115In para cobrir grande parte do espectro de energia dos nêutrons. Após a irradiação, os detectores de ativação foram submetidos a espectrometria gama utilizando um sistema de contagem com Germânio hiper-puro, afim de se obter a taxa de reação (atividade de saturação) por núcleo alvo. As razões espectrais foram comparadas com valores obtidos através do método de Monte Carlo utilizando o código MCNP-4C. O espectro de energia de nêutrons foi obtido no interior da vareta combustível utilizando o código SANDBP com um espectro de entrada obtido pelo código MCNP-4C, a partir dos valores de atividade de saturação por núcleo alvo dos detectores de ativação irradiados. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-01-19T10:26:11Z No. of bitstreams: 0 / Made available in DSpace on 2015-01-19T10:26:11Z (GMT). No. of bitstreams: 0 / Um dos parâmetros fundamentais da física de reatores é a curvatura do fluxo de nêutrons (Buckling) do núcleo do reator. Ele está relacionado com outros parâmetros importantes, tais como as taxas de reação, potencia de operação, queima de combustível, entre outros. Num reator crítico, o Buckling depende das características geométricas e de material do núcleo do reator. Este trabalho apresenta os resultados do Buckling experimental para o reator nuclear IPEN/MB-01 em sua configuração cilíndrica com 28 barras de combustível ao longo de seu diâmetro. O IPEN/MB-01 é um reator de potência zero projetado para operar em uma potência máxima nominal de 100 watts. É uma instalação nuclear versátil que permite a simulação de todas as características de um grande reator nuclear e ideal para este tipo de medição. Foi realizado um mapeamento do fluxo de nêutrons no interior do reator e, assim, determinado o Buckling total da configuração cilíndrica. O reator foi operado durante uma hora para cada experimento. Em seguida, a taxa de reação nuclear das varetas de combustível foram medidas por espectrometria gama em um detector de germânio hiper-puro (HPGe) que escaneou as varetas axial e radialmente. Foram analisados os fótons gama do 239Np ( 276,6 keV ), gerado a partir da captura de nêutrons epitérmicos e rápidos, e do 143Ce ( 293,3 keV ), gerado por fissão em ambos 238U e 235U, respectivamente. Foram analisadas as direções axial e radial. Outras medições foram realizadas com fios e folhas de ouro nas direções radial e axial do núcleo do reator. O Buckling total obtido a partir da média ponderada dos três métodos medidos é de 96,55 ± 7,47 m-2. Os objetivo dos valores experimentais obtidos é obter um conjunto de dados experimentais que permitam uma comparação direta com valores calculados pelos códigos de Física de Reatores CITATION e MCNP. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

The purpose of this study is to empirically investigate if the municipal decision on wind power development can be explained by a model including socioeconomic variables and proxies for the natural environment, using a pooled cross-section data set for Swedish municipalities for the period 2010-2019. The study poses the question whether politicians' decisions-making can be explained by socioeconomic factors. In order to analyse the approving or denying of wind power development in Swedish municipalities, three models are used: the linear probability model, the probit and the logit model. The results show that the Green political party (positively affecting wind power development) and that the unemployment rate, income, population density, protected areas and the affiliations with the Sweden Democrats (negatively affecting the approval rate), has a statistical significant effect on the permissionprocess. Installed capacity of wind power plants seemingly have no impact. Our findings suggest that the municipal decision making is less random than the critics of the municipal veto proposes.

In photodynamic therapy a photosensitizer drug is administered and is irradiated with light. Upon absorption of light the photosensitizer goes into its triplet state and transfers energy or an electron to oxygen to form reactive oxygen species (ROS). These ROS react with biomolecules in cells leading to cell damage and cell death. PDT has interested many researchers because of its non-invasiveness as compared to surgery, it leaves little to no scars, it is time and cost effective, it has potential for targeted treatment, and can be repeated as needed. Different photosensitizers such as porphyrines, chlorophylls, and dyes have been used in PDT to treat various cancers, skin diseases, aging and sun-damaged skin. These second generation sensitizers have yielded reduced skin sensitivity and improved extinction coefficients (up to ~ 105 L mol-1 cm-1). While PDT based on small molecule photosensitizers has shown great promise, several problems remain unsolved. The main issues with current sensitizers are (i) hydrophobicity leading to aggregation in aqueous media resulting in reduced efficacy and potential toxicity, (ii) dark toxicity of photosensitizers, (iii) non-selectivity towards malignant tissue resulting in prolonged cutaneous photosensitivity and damage to healthy tissue, (iv) limited light absorption efficiency, and (v) a lack of understanding of where the photosensitizer ends up in the tissue. In this dissertation research program, these issues were addressed by the development of conducting polymer nanoparticles as a next generation of photosensitizers. This choice was motivated by the fact that conducting polymers have large extinction coefficients ( > 107 L mol-1 cm-1), are able to undergo intersystem crossing to the triplet state, and have triplet energies that are close to that of oxygen. It was therefore hypothesized that such polymers could be effective at generating ROS due to the large excitation rate that can be generated. Conducting polymer nanoparticles (CPNPs) composed of the conducting polymer poly[2-methoxy-5-(2-ethylhexyl-oxy)-p-phenylenevinylene] (MEH-PPV) were fabricated and studied in-vitro for their potential in PDT application. Although not fully selective, the nanoparticles exhibited a strong bias to the cancer cells. The formation of ROS was proven in-vitro by staining of the cells with CellROX Green Reagent, after which PDT results were quantified by MTT assays. Cell mortality was observed to scale with nanoparticle dosage and light dosage. Based on these promising results the MEH-PPV nanoparticles were developed further to allow for surface functionalization, with the aim of targeting these NPs to cancer cell lines. For this work targeting of cancers that overexpress folate receptors (FR) were considered. The functionalized nanoparticles (FNPs) were studied in OVCAR3 (ovarian cancer cell line) as FR+, MIA PaCa2 (pancreatic cell line) as FR-, and A549 (lung cancer cell line) having marginal FR expression. Complete selectivity of the FNPs towards the FR+ cell line was found. Quantification of PDT results by MTS assays and flow cytometry show that PDT treatment was fully selective to the FR+ cell line (OVCAR3). No cell mortality was observed for the other cell lines studied here within experimental error. Finally, the issue of confirming and quantifying small molecule drug delivery to diseased tissue was tackled by developing quantum dot (Qdot) biosensors with the aim of achieving fluorescence reporting of intracellular small molecule/drug delivery. For fluorescence reporting prior expertise in control of the fluorescence state of Qdots was employed, where redox active ligands can place the Qdot in a quenched OFF state. Ligand attachment was accomplished by disulfide linker chemistry. This chemistry is reversible in the presence of sulfur reducing biomolecules, resulting in Qdots in a brightly fluorescent ON state. Glutathione (GSH) is such a biomolecule that is present in the intracellular environment. Experimental in-vitro data shows that this design was successfully implemented.

No description available.

Micro and nanofabrication technologies have been used extensively in many biomedical and biological applications. Integration of MEMS technology and biology (BioMEMS) enables precise control of the cellular microenvironments and offers high throughput systems. The focus of this research was to develop three dimensional (3-D) isotropic microstructures for comprehensive analysis on cell-substrate interactions. The aim was to investigate whether the normal and cancerous cells differentially respond to their underlying substrate and whether the differential response of the cells leads to a novel label-free technique to distinguish between normal and cancerous cells. Three different generations of 3-D isotropic microstructures comprised of curved surfaces were developed using a single-mask, single-etch step process. Our experimental model included HS68 normal human fibroblasts, MCF10A normal human breast epithelial cells and MDA-MB-231 metastatic human breast cancer cells. Primary findings on the first generation of silicon substrates demonstrated a distinct adhesion and growth behavior in HS68 and MDA-MB-231 cells. MDA-MB-231 cells deformed while the fibroblasts stretched and elongated their cytoskeleton on the curved surfaces. Unlike fibroblasts, MDA-MB-231 cells mainly trapped and localized inside the deep microchambers. Detailed investigations on cytoskeletal organization, adhesion pattern and morphology of the cells on the second generation of the silicon substrates demonstrated that cytoskeletal prestress and microtubules organization in HS68 cells, cell-cell junction and cell-substrate adhesion strength in MCF10A cells, and deformability of MDA-MB-231 cells (obtained by using AFM technique) affect their behavior inside the etched cavities. Treatment of MDA-MB-231 cells with experimental breast cancer drug, SAHA, on the second generation of substrates, significantly altered the cells morphology, cytoarchitecture and adhesion pattern inside the 3-D microstructures. Third generation of silicon substrates was developed for comprehensive analysis on behavior of MDA-MB-231 and MCF10A cells in a co-culture system in response to SAHA drug. Formation of colonies of both cell types was evident inside the cavities within a few hours after seeding the cells on the chips. SAHA selectively altered the morphology and cytoarchitecture in MDA-MB-231 cells. Most importantly, the majority of MDA-MB-231 cells stretched inside the etched cavities, while the adhesion pattern of MCF10A cells remained unaltered. In the last part of this dissertation, using AFM analysis, we showed that the growth medium composition has a pronounced effect on cell elasticity. Our findings demonstrated that the proposed isotropic silicon microstructures have potential applications in development of biosensor platforms for cell segregation as well as conducting fundamental biological studies. / Ph. D.

No description available.