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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.
21

Desenvolvimento de técnica de análise de imagens digitais para avaliação do estágio da fibrose em biópsias hepáticas de pacientes portadores de hepatite crônica por vírus da hepatite B e C / Development of a digital image analysis technique for the evaluation of fibrosis stage in liver biopsies of HBV and HCV patients

Carlos Frederico Ferreira Campos 26 January 2011 (has links)
As hepatites crônicas por vírus são as mais frequentes, destacando-se os vírus das hepatites B (VHB) e C (VHC). O estudo anatomopatológico da biópsia hepática é considerado o padrão ouro para avaliar com precisão a distorção arquitetural e o grau de fibrose do parênquima do fígado, importantes fatores prognósticos para os pacientes portadores de hepatites crônicas virais. Na avaliação histopatológica atual, em adição aos relatos subjetivos das alterações histológicas, escores semiquantitativos que correlacionam achados morfológicos com graus numéricos são usados, tais como os reconhecidos escores de Ishak e METAVIR. Entretanto, em todos estes sistemas há a desvantagem da subjetividade do examinador e da incorporação de alterações categóricas, sem referências às mudanças quantitativas do colágeno hepático. Técnicas de análise de imagens digitais (AID) que fornecem quantificação objetiva dos graus de fibrose em amostras histológicas têm sido desenvolvidas. Todavia, o alto custo e dificuldade ao acesso das tecnologias descritas restringem seu uso a poucos centros especializados. Este estudo visa o desenvolvimento de uma técnica de custo acessível para a análise de imagens digitais da fibrose hepática em hepatites crônicas virais. Foram estudadas 304 biópsias de pacientes com hepatite crônica por vírus B e C, obtidas através de agulhas Menghini. Todas as amostras tinham pelo menos 15 mm de comprimento ou cinco espaços-porta completos e foram coradas pelo método Tricrômico de Masson. O estadiamento foi feito por um único hepatopatologista experiente, sem o conhecimento dos dados clínicos dos pacientes. Os escores de Ishak e METAVIR foram aplicados. As imagens microscópicas foram digitalizadas. Os índices de fibrose foram determinados de forma automatizada, em técnica desenvolvida no programa Adobe Photoshop. Para o escore de Ishak, observamos os seguintes índices de Fibrose (IF) médios: 0,8% 0,0 (estágio 0), 2.4% 0,6 (estágio 1), 4,7% 1,6 (estágio 2), 7,4% 1,4 (estágio 3), 14,9% 3,7 (estágio 4), 23,4% 2,9 (estágio 5) e 34,5% 1,5 (estágio 6). Para a classificação METAVIR: 0,8% 0,1 (estágio F0), 3,8% 1,8 (estágio F1), 7,4% 1,4 (estágio F2), 20,4% 5,2 (estágio F3) e 34,5% 1,5 (estágio F4). Observamos uma excelente correlação entre os índices de fibrose da AID e os escores de Ishak (r=0,94; p<0,001) e METAVIR (r=0,92; p<0,001). Em relação à indicação de tratamento antiviral, foi observado IF médio de 16,4%. Em relação ao diagnóstico de cirrose, foi observado IF médio de 26,9%, para o escore de Ishak, e 34,5% para a classificação METAVIR. A reprodutibilidade intra-observador foi excelente. Este novo método de análise de imagens digitais para a quantificação de fibrose hepática tem custo acessível e foi desenvolvido com tecnologia que está disponível em todo o mundo, permitindo identificar com precisão todos os estágios de fibrose, com excelente reprodutibilidade intra-observador. / The hepatitis caused by viruses are the most frequent, principally the virus B (HBV) and C (HCV) hepatitis. The anatomopathologic study of the liver biopsy is considered the gold standard for the evaluation of architectural distortion and degree o fibrosis of the livers parenchyma, important prognostic factors for the patients with chronic viral hepatitis. In the actual histopathological evaluation, in addition to subjective reports of histological alterations, semiquantitative scores that correlate morphological findings with numeric degrees are used, such as the renowned Ishak and METAVIR scores. However, in all of these systems there is the disadvantage of the subjectiveness of the examinator and the incorporation of categorical description of architectural changes without reference to quantitative changes in liver collagen. Digital Image Analysis techniques (DIA) that provide objective quantification of the degrees of liver fibrosis in histological samples have been developed. But the high cost and worldwide unavailability of the technologies described restrained their use to a few specialized centers. This study aims at developing an affordable technique for livers fibrosis DIA in chronic viral hepatitis. Three hundred and four core needle biopsies obtained by Menghini needles from patients with virus B and virus C hepatitis were studied. All samples had at least 15 mm in length or five complete portal tracts and were stained with the Massons Trichrome Method. The staging by Ishaks and METAVIRs scores was done by a single experienced hepatopathologist, without the knowledge patients clinical data. The microscopic images were digitalized. The fibrosis indexes were calculated in an automated way by a new technique developed in the Adobe Photoshop software. For the Ishak score the following median Fibrosis Indexes (FI) were observed: 0,8% 0,0 (stage 0), 2.4% 0,6 (stage 1), 4,7% 1,6 (stage 2), 7,4% 1.4 (stage 3), 14,9% 3.7 (stage 4), 23,4% 2.9 (stage 5) e 34,5% 1,5 (stage 6). For the METAVIR classification: 0,8% 0,1 (stage F0), 3,8% 1.8 (stage F1), 7,4% 1.4 (stage F2), 20,4% 5,2 (stage F3) e 34,5% 1,5 (stage F4). We found an excellent correlation between the DIA fibrosis indexes and the Ishaks (r=0.94; p<0.001) and METAVIR (r=0.92; p<0.001) stages. In relation to the indication for antiviral treatment, the mean FI observed was 16.4% for both classifications. In relation to cirrhosiss diagnosis, the mean FI observed was 26.9% for Ishaks score, and 34.5% for METAVIRs classification. There was excellent intraobserver reproducibility. This new method of digital image analysis for liver fibrosis quantification is affordable and was developed using technology that is available worldwide, allowing the precise identification of all the stages of fibrosis in the group of patients studied, with excellent intraobserver reproducibility.
22

MULTIVARIATE ANALYSIS TO IDENTIFY POTENTIAL BIOMARKERS FOR PROGNOSIS AND TREATMENT RESISTANCE IN HEAD AND NECK CANCER PATIENTS

Wicker, Christina Ann 01 January 2018 (has links)
It is estimated that nearly 50,000 individuals in the United States will be diagnosed with head and neck cancer in 2017 (American Cancer Society www.cancer.org). Ninety percent of oral cancers are head and neck squamous cell carcinoma (HNSCC). Major obstacles in the treatment of HNSCC are recurrence and treatment resistance, which contributes to increased mortality. Therefore, there is increased need to determine genetic alterations in HNSCC that may be ideal novel drug targets, and biomarkers to improve diagnostic and prognostic testing. Abnormal localization and overexpression of base excision repair protein and transcriptional regulator Apurinic/Apyrimidic endonuclease (APE1) has been associated with treatment resistance and poor prognosis. Therefore, we explored mechanisms for how APE1 contributes to treatment resistance and increased mortality in HNSCC. Because oxidative stress heavily influences APE1’s expression and transcriptional regulatory activities, we examined genes involved in oxidative stress management, including SOD3 and NRF2. PPARGC1A, a NRF2 transcriptional co-activator, was also examined as our lab previously observed a link between APE1 and PPARGC1A expression. This previous work also revealed that APE1 suppressed gene expression of tumor suppressor, decorin (DCN). To examine possible mechanisms for how APE1 regulates expression of tumor suppressors and antioxidants, digital image analysis of immunohistochemistry staining was used to identify alterations in protein expression. Nuclear and total cellular protein expression of APE1, DCN, NRF2, PPARGC1A, and SOD3 were quantified in regions of proximal benign, carcinoma in situ (CIS) and invasive HNSCC. Patient survival analysis revealed that increased APE1, DCN, and PPARGC1A protein levels were significantly associated with reduced survival in CIS, benign, and invasive tissues respectively. Using multivariate analysis of protein expression, we identified that increased APE1 protein levels in the CIS of primary tumors were associated with the presence of cancer invaded lymph nodes. Elevated DCN and SOD3 protein levels in benign tissue were associated with poorly differentiated tumors as was reduced PPARGC1A in CIS. Most importantly, potential prognostic biomarkers for use in early cancer development were identified. Identifying poor prognosis in early cancer development allows the possibility of improved treatment strategies, which could prevent invasive cancer development, and increase patient survival.
23

Digital Image Analysis of Cells : Applications in 2D, 3D and Time

Pinidiyaarachchi, Amalka January 2009 (has links)
Light microscopes are essential research tools in biology and medicine. Cell and tissue staining methods have improved immensely over the years and microscopes are now equipped with digital image acquisition capabilities. The image data produced require development of specialized analysis methods. This thesis presents digital image analysis methods for cell image data in 2D, 3D and time sequences. Stem cells have the capability to differentiate into specific cell types. The mechanism behind differentiation can be studied by tracking cells over time. This thesis presents a combined segmentation and tracking algorithm for time sequence images of neural stem cells.The method handles splitting and merging of cells and the results are similar to those achieved by manual tracking. Methods for detecting and localizing signals from fluorescence stained biomolecules are essential when studying how they function and interact. A study of Smad proteins, that serve as transcription factors by forming complexes and enter the cell nucleus, is included in the thesis. Confocal microscopy images of cell nuclei are delineated using gradient information, and Smad complexes are localized using a novel method for 3D signal detection. Thus, the localization of Smad complexes in relation to the nuclear membrane can be analyzed. A detailed comparison between the proposed and previous methods for detection of point-source signals is presented, showing that the proposed method has better resolving power and is more robust to noise. In this thesis, it is also shown how cell confluence can be measured by classification of wavelet based texture features. Monitoring cell confluence is valuable for optimization of cell culture parameters and cell harvest. The results obtained agree with visual observations and provide an efficient approach to monitor cell confluence and detect necrosis. Quantitative measurements on cells are important in both cytology and histology. The color provided by Pap (Papanicolaou) staining increases the available image information. The thesis explores different color spaces of Pap smear images from thyroid nodules, with the aim of finding the representation that maximizes detection of malignancies using color information in addition to quantitative morphological parameters. The presented methods provide useful tools for cell image analysis, but they can of course also be used for other image analysis applications.
24

Desenvolvimento de um método computacional para avaliação da conformidade de cones obturadores acessórios / A computerized routine of digital image analysis as an efficient approach to evaluate the standardization quality of filling cones

Cristiane Audi 12 February 2008 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Esse trabalho teve como objetivo avaliar a qualidade de padronização dos cones acessórios Fine Medium (FM), Medium (M) e Medium Large (ML) de cinco diferentes marcas comerciais de cones de guta-percha e de uma marca de cone Resilon, através do desenvolvimento de um método automático de processamento e análise digital de imagens. Para tal, 21 cones de cada conicidade e marca comercial foram digitalizados em um scanner com 1200 DPI, o que implica em uma precisão de 0.021 mm, e uma rotina de processamento digital das imagens foi desenvolvida para obter medições automáticas dos seguintes parâmetros: diâmetro da ponta (D0), diâmetro a 3 mm da ponta (D3), diâmetro a 16 mm da ponta (D16), comprimento (L) e conicidade (C). As medidas encontradas foram submetidas a análises estatísticas e comparações entre os grupos das médias de cada parâmetro avaliado. As especificações ANSI/ADA números 57 e 78 foram empregadas como referências para a análise da estandardização dos cones testados. De posse dos resultados, foi possível concluir que existe uma ineficaz padronização dos cones obturadores, os quais apresentaram grandes variações entre as diversas marcas testadas e dentro de uma mesma marca. O método desenvolvido para medição dos parâmetros de controle dos cones se mostrou bastante eficaz, gerando resultados confiáveis. / The present study aimed to evaluate the standardization quality of the accessory gutta-percha cones Fine Medium (FM), Medium (M) and Medium Large (ML) of five different commercial brands of gutta-percha cones and a brand of Resilon cone, through the development of an automated method of digital image processing and analysis sequence. Hence, 21 cones of each conicity and commercial brand were digitalized with a scanner with 1200 DPI, which implicates on a precision of 0,021mm and a sequence of digital image processing were developed to obtain automatic measures of the following parameters: D0, D3, D16, length (L) and conicity (C). The measures found were submitted to statistical analysis and comparisons among the groups of the means of each parameter evaluated. Numbers 57 and 78 ANSI/ADA specifications were used as references to the standardization analysis of the tested cones. Based on the results obtained it was possible to conclude that there is an inefficient standardization of obturating cones, which presented large variations among the different tested brands and in a single brand also. The method developed to measure the parameters of the obturating cones control group was very efficient, producing reliable results.
25

Desenvolvimento de um método computacional para avaliação da conformidade de cones obturadores acessórios / A computerized routine of digital image analysis as an efficient approach to evaluate the standardization quality of filling cones

Cristiane Audi 12 February 2008 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Esse trabalho teve como objetivo avaliar a qualidade de padronização dos cones acessórios Fine Medium (FM), Medium (M) e Medium Large (ML) de cinco diferentes marcas comerciais de cones de guta-percha e de uma marca de cone Resilon, através do desenvolvimento de um método automático de processamento e análise digital de imagens. Para tal, 21 cones de cada conicidade e marca comercial foram digitalizados em um scanner com 1200 DPI, o que implica em uma precisão de 0.021 mm, e uma rotina de processamento digital das imagens foi desenvolvida para obter medições automáticas dos seguintes parâmetros: diâmetro da ponta (D0), diâmetro a 3 mm da ponta (D3), diâmetro a 16 mm da ponta (D16), comprimento (L) e conicidade (C). As medidas encontradas foram submetidas a análises estatísticas e comparações entre os grupos das médias de cada parâmetro avaliado. As especificações ANSI/ADA números 57 e 78 foram empregadas como referências para a análise da estandardização dos cones testados. De posse dos resultados, foi possível concluir que existe uma ineficaz padronização dos cones obturadores, os quais apresentaram grandes variações entre as diversas marcas testadas e dentro de uma mesma marca. O método desenvolvido para medição dos parâmetros de controle dos cones se mostrou bastante eficaz, gerando resultados confiáveis. / The present study aimed to evaluate the standardization quality of the accessory gutta-percha cones Fine Medium (FM), Medium (M) and Medium Large (ML) of five different commercial brands of gutta-percha cones and a brand of Resilon cone, through the development of an automated method of digital image processing and analysis sequence. Hence, 21 cones of each conicity and commercial brand were digitalized with a scanner with 1200 DPI, which implicates on a precision of 0,021mm and a sequence of digital image processing were developed to obtain automatic measures of the following parameters: D0, D3, D16, length (L) and conicity (C). The measures found were submitted to statistical analysis and comparisons among the groups of the means of each parameter evaluated. Numbers 57 and 78 ANSI/ADA specifications were used as references to the standardization analysis of the tested cones. Based on the results obtained it was possible to conclude that there is an inefficient standardization of obturating cones, which presented large variations among the different tested brands and in a single brand also. The method developed to measure the parameters of the obturating cones control group was very efficient, producing reliable results.
26

Desenvolvimento de técnica de análise de imagens digitais para avaliação do estágio da fibrose em biópsias hepáticas de pacientes portadores de hepatite crônica por vírus da hepatite B e C / Development of a digital image analysis technique for the evaluation of fibrosis stage in liver biopsies of HBV and HCV patients

Carlos Frederico Ferreira Campos 26 January 2011 (has links)
As hepatites crônicas por vírus são as mais frequentes, destacando-se os vírus das hepatites B (VHB) e C (VHC). O estudo anatomopatológico da biópsia hepática é considerado o padrão ouro para avaliar com precisão a distorção arquitetural e o grau de fibrose do parênquima do fígado, importantes fatores prognósticos para os pacientes portadores de hepatites crônicas virais. Na avaliação histopatológica atual, em adição aos relatos subjetivos das alterações histológicas, escores semiquantitativos que correlacionam achados morfológicos com graus numéricos são usados, tais como os reconhecidos escores de Ishak e METAVIR. Entretanto, em todos estes sistemas há a desvantagem da subjetividade do examinador e da incorporação de alterações categóricas, sem referências às mudanças quantitativas do colágeno hepático. Técnicas de análise de imagens digitais (AID) que fornecem quantificação objetiva dos graus de fibrose em amostras histológicas têm sido desenvolvidas. Todavia, o alto custo e dificuldade ao acesso das tecnologias descritas restringem seu uso a poucos centros especializados. Este estudo visa o desenvolvimento de uma técnica de custo acessível para a análise de imagens digitais da fibrose hepática em hepatites crônicas virais. Foram estudadas 304 biópsias de pacientes com hepatite crônica por vírus B e C, obtidas através de agulhas Menghini. Todas as amostras tinham pelo menos 15 mm de comprimento ou cinco espaços-porta completos e foram coradas pelo método Tricrômico de Masson. O estadiamento foi feito por um único hepatopatologista experiente, sem o conhecimento dos dados clínicos dos pacientes. Os escores de Ishak e METAVIR foram aplicados. As imagens microscópicas foram digitalizadas. Os índices de fibrose foram determinados de forma automatizada, em técnica desenvolvida no programa Adobe Photoshop. Para o escore de Ishak, observamos os seguintes índices de Fibrose (IF) médios: 0,8% 0,0 (estágio 0), 2.4% 0,6 (estágio 1), 4,7% 1,6 (estágio 2), 7,4% 1,4 (estágio 3), 14,9% 3,7 (estágio 4), 23,4% 2,9 (estágio 5) e 34,5% 1,5 (estágio 6). Para a classificação METAVIR: 0,8% 0,1 (estágio F0), 3,8% 1,8 (estágio F1), 7,4% 1,4 (estágio F2), 20,4% 5,2 (estágio F3) e 34,5% 1,5 (estágio F4). Observamos uma excelente correlação entre os índices de fibrose da AID e os escores de Ishak (r=0,94; p<0,001) e METAVIR (r=0,92; p<0,001). Em relação à indicação de tratamento antiviral, foi observado IF médio de 16,4%. Em relação ao diagnóstico de cirrose, foi observado IF médio de 26,9%, para o escore de Ishak, e 34,5% para a classificação METAVIR. A reprodutibilidade intra-observador foi excelente. Este novo método de análise de imagens digitais para a quantificação de fibrose hepática tem custo acessível e foi desenvolvido com tecnologia que está disponível em todo o mundo, permitindo identificar com precisão todos os estágios de fibrose, com excelente reprodutibilidade intra-observador. / The hepatitis caused by viruses are the most frequent, principally the virus B (HBV) and C (HCV) hepatitis. The anatomopathologic study of the liver biopsy is considered the gold standard for the evaluation of architectural distortion and degree o fibrosis of the livers parenchyma, important prognostic factors for the patients with chronic viral hepatitis. In the actual histopathological evaluation, in addition to subjective reports of histological alterations, semiquantitative scores that correlate morphological findings with numeric degrees are used, such as the renowned Ishak and METAVIR scores. However, in all of these systems there is the disadvantage of the subjectiveness of the examinator and the incorporation of categorical description of architectural changes without reference to quantitative changes in liver collagen. Digital Image Analysis techniques (DIA) that provide objective quantification of the degrees of liver fibrosis in histological samples have been developed. But the high cost and worldwide unavailability of the technologies described restrained their use to a few specialized centers. This study aims at developing an affordable technique for livers fibrosis DIA in chronic viral hepatitis. Three hundred and four core needle biopsies obtained by Menghini needles from patients with virus B and virus C hepatitis were studied. All samples had at least 15 mm in length or five complete portal tracts and were stained with the Massons Trichrome Method. The staging by Ishaks and METAVIRs scores was done by a single experienced hepatopathologist, without the knowledge patients clinical data. The microscopic images were digitalized. The fibrosis indexes were calculated in an automated way by a new technique developed in the Adobe Photoshop software. For the Ishak score the following median Fibrosis Indexes (FI) were observed: 0,8% 0,0 (stage 0), 2.4% 0,6 (stage 1), 4,7% 1,6 (stage 2), 7,4% 1.4 (stage 3), 14,9% 3.7 (stage 4), 23,4% 2.9 (stage 5) e 34,5% 1,5 (stage 6). For the METAVIR classification: 0,8% 0,1 (stage F0), 3,8% 1.8 (stage F1), 7,4% 1.4 (stage F2), 20,4% 5,2 (stage F3) e 34,5% 1,5 (stage F4). We found an excellent correlation between the DIA fibrosis indexes and the Ishaks (r=0.94; p<0.001) and METAVIR (r=0.92; p<0.001) stages. In relation to the indication for antiviral treatment, the mean FI observed was 16.4% for both classifications. In relation to cirrhosiss diagnosis, the mean FI observed was 26.9% for Ishaks score, and 34.5% for METAVIRs classification. There was excellent intraobserver reproducibility. This new method of digital image analysis for liver fibrosis quantification is affordable and was developed using technology that is available worldwide, allowing the precise identification of all the stages of fibrosis in the group of patients studied, with excellent intraobserver reproducibility.
27

[en] PHYSICAL SIMULATION AND CHARACTERIZATION OF HEAT AFFECTED ZONE (HAZ) IN DUPLEX STAINLESS STEELS / [pt] SIMULAÇÃO FÍSICA E CARACTERIZAÇÃO MICROESTRUTURAL E MECÂNICA DA ZONA TERMICAMENTE AFETADA (ZTA) EM AÇOS INOXIDÁVEIS DUPLEX

LILIA OLAYA LUENGAS 06 February 2018 (has links)
[pt] Os aços inoxidáveis duplex (AID) possuem uma estrutura mista de Delta-ferrita e Gamma-austenita em frações de volume aproximadamente iguais e combinam muitas das propriedades benéficas das duas fases, a ferrita fornece alta resistência mecânica e resistência à corrosão, enquanto que a austenita aumenta a ductilidade e a resistência à corrosão uniforme. Uma vantagem dos AID é a resistência à trincas de solidificação, que está associado à soldagem. Pela combinação de propriedades, esses aços são amplamente utilizados na indústria de equipamentos químicos, petróleo e gás, plantas de dessalinização, controle de poluição, usinas elétricas e, mais recentemente, em aplicações off-shore como na extração de petróleo em águas profundas. No entanto, a exposição destes aços a temperaturas elevadas entre 600 graus celsius e 1000 graus celsius, que ocorre durante a soldagem por fusão resulta na precipitação de diferentes compostos, sendo os mais frequentemente encontrados a fase sigma, a fase x, os nitretos de cromo e os carbonetos que reduzem tanto a resistência mecânica quanto a resistência a corrosão. Este trabalho teve como objetivo simular fisicamente as microestruturas da zona termicamente afetada (ZTA) dos AIDs UNS S32304, S32205 e S32750. De modo a obter diferentes ZTAs foi utilizado o simulador termo-mecânico Gleeble, por meio deste simulador foram aplicados vários aportes de calor que permitiram avaliar a evolução microestrutural e as propriedades mecânicas destas zonas. As temperaturas utilizadas nas simulações físicas foram determinadas por meio do software Thermo-Calc assegurando assim as faixas de transformações microestruturais. A temperatura de pico utilizada foi de 1350 graus celsius por 2 segundos; seguida de resfriamento em acordo com o modelo Rykalin-2D, onde um grupo de amostras sofreu resfriamento até alcançar a temperatura de 500 graus celsius seguido de uma têmpera em água e um outro grupo até 250 graus celsius seguido de uma têmpera. Este procedimento foi adotado de modo a identificar a influência dos aportes de calor e as taxas de resfriamento na frações volumétricas das fases obtidas. Foi observado um aumento da fração volumétrica da austenita, assim como um aumento do tamanho de grão da ferrita e um crescimento nos grãos da austenita, em função do aumento do aporte de calor durante as simulações físicas das ZTAs. Estas variações microestruturais ocasionaram o decréscimo da resistência mecânica nos três AID avaliados quando comparados ao respectivo metal de base. / [en] The duplex stainless steels (DSS) have a structure that consist of approximately equivalent amounts of delta-austenita and gamma-ferrite, exhibit excellent properties combinations of both phases. DSS combine the high strength and resistance to stress corrosion cracking come from ferrite, whereas the austenite phase influences ductility and uniform corrosion resistance. The advantage of DSS is solidification cracking resistance; it is associated to welding processes. The application of DSS have being increasingly used as structural material in various industrial sectors, such as chemical, petrochemical, pulp and paper, power generation, desalination, oil and gas, for the constructions in marine and chemical industries and most recently for manufacturing components used in off-shore oil platforms for oil extraction in deep water. However, the exposure of these steels to high temperatures between 600 celsius degrees and 1000 celsius degrees, which occurs during fusion welding results in different compounds precipitation, the most frequently encountered being the sigma phase, the X phase, the chromium nitrides and carbides which reduce both mechanical strength and corrosion resistance. The aim of this work was to simulate physically the Heat Affected Zone (HAZ) microstructures in DSS UNS S32304, S32205 and S32750. In order to obtain different HAZ the Gleeble system was used. Several heat inputs were applied through this simulator, which allowed evaluate the microstructural evolution and the mechanical properties of these zones. The temperatures used in physical simulations were determined by Thermo-Calc Software, this supplied the microstructural transformations temperature ranges. The peak temperature used was 1350 celsius degrees for 2 seconds; followed by cooling in accordance with the Rykalin-2D model; one sample set was cooled to 500 celsius degrees followed by water quenching, and the second sample set was cooled to 250 celsius degrees followed by quenching. This procedure was adopted in order to identify the effect of the final temperature on the phases volume fraction obtained. An increase in the austenite volume fraction, as well as an increase in the ferrite grain size and a widening in the austenite grains, due to the increase of the heat input during the physical simulations of the ZTAs was observed. These microstructural variations caused the tensile strength and Yield strength decreasing in HAZ of DSS evaluated when these zones were compared to the respective base metal.
28

Shape Characterization of Granular Particles using Image Based Techniques

Roy, Nimisha January 2017 (has links) (PDF)
Granular soils with different sizes and shapes are often used in many civil engineering structures. In different contexts, several researchers have emphasized that shape of particles play a pivotal role in influencing several engineering properties such as maximum and minimum packing densities, shear strength, permeability and compressibility. However, the complexities involved in obtaining the geometrical parameters necessary to adequately compute particle shape have hampered the clear understanding of the contribution of particle shape to such properties. Researchers have attempted to characterize the shape of the particles by many conventional and advanced image based methods in the past. However, these methods suffer from many criticisms; conventional methods of shape characterization include ocular inspection of particles based on visual reference charts, which are more prone to user dependent interpretations. The recently developed image based methods deviate from the conventional and most well accepted definitions formulated by researchers in the past due to the difficulties involved in automating them. The aim of this thesis is to address this shortcoming by developing a robust methodology for accurate and precise determination of particle shape in accordance with the most widely accepted formulae in literature, which can replace the existing methods based on manual measurements, approximate visual charts and non-robust imaging techniques. For this purpose, several computational algorithms are written and implemented in MATLAB and operations are performed on particle images. These methods are developed to precisely characterize the particles shape parameters observed at three levels of scales, which are adequate for complete shape characterization. According to Barrett (1980) the particle shape features can be observed independently at three different scales, viz. macro-scale, meso-scale and micro-scale, the shape parameters such as form, roundness and surface texture falls into these three scales respectively. The macro-scale component of form (sphericity) is quantified as per the formula used in the visual chart proposed by Krumbein & Sloss (1951). In light of its continuing popularity and wide usage, the roundness concept proposed by Wadell (1932) is chosen to be the appropriate parameter for meso-scale shape representation. The micro-scale component of surface texture or roughness is measured by the conventional and widely used root mean square definition, by incorporating the use of digital filtering techniques. The distinct concept of angularity as proposed by Lees (1964) is used for effective shape representation of crushed particles. Kinematic behaviour of particles such as sliding, rolling and interlocking are dependent on the geometrical features observed at meso-scale present along their boundaries, which consequently govern the material strength and deformation characteristics. Based on precise identification of such features (concavo-convex regions along particle boundary), a new classification chart is proposed in this thesis to comprehend the kinematics of particles. The effects of critical parameters such as scale, resolution and user defined cutoff values on the quantification of shape parameters are analyzed and eliminated. The proposed methodology is compared with standard visual charts provided by earlier researchers and is demonstrated on real soil particles falling across a wide range of sizes and shapes. Finally, the role of particle shape in governing packing behaviour of aggregates is quantified based on the precise particle shape characterization.
29

Optimizing Topramezone and Other Herbicide Programs for Weed Control in Bermudagrass and Creeping Bentgrass Turf

Brewer, John Richard 02 April 2021 (has links)
Goosegrass [Eleusine indica (L.) Gaertn.] and smooth crabgrass [Digitaria ischaemum (Schreb.) Schreb. ex Muhl.] are problematic weeds in bermudagrass and creeping bentgrass turf. Increased incidences of herbicide resistant weed populations and severe use restrictions on formerly available herbicides have increased need for selective, postemergence control options for these weeds in creeping bentgrass and bermudagrass turf. This weed management exigency has led turf managers to utilize less effective, more expensive, and more injurious options to manage goosegrass and smooth crabgrass. Although potentially injurious, topramezone can control these weeds, especially goosegrass, at low doses. Low-dose topramezone may also improve bermudagrass and creeping bentgrass response. An initial investigation of three 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibiting herbicides in different turf types showed that Kentucky bluegrass, perennial ryegrass, and tall fescue were highly tolerant to topramezone, while creeping bentgrass and bermudagrass could tolerate topramezone doses that may control grassy weeds. Further investigation suggested that frequent, low-dose topramezone applications or metribuzin admixtures could enhance weed control and may conserve turfgrass quality. A novel mixture of topramezone at 3.7 g ae ha-1 and metribuzin at 210 g ai ha-1 controlled goosegrass effectively and reduced bermudagrass foliar bleaching associated with topramezone 10-fold compared to higher doses of topramezone alone in 19 field and 2 greenhouse trials. In an attempt to further enhance bermudagrass tolerance to topramezone, post-treatment irrigation was applied at various timings. When bermudagrass turf was irrigated with 0.25-cm water at 15 or 30 minutes after herbicide treatment, bermudagrass injury was reduced to acceptable levels when following low-dose topramezone plus metribuzin but not when following high-dose topramezone alone. Goosegrass control was reduced significantly by post-treatment irrigation in all cases, while irrigation reduced goosegrass control by low-dose topramezone plus metribuzin to below-commercially-acceptable levels. Novel, low-dose, frequent application programs containing topramezone or siduron were developed for season-long crabgrass or goosegrass control on creeping bentgrass greens. Greens-height creeping bentgrass quality was preserved following five biweekly treatments of siduron at rates between 3,400 to 13,500 g ai ha-1 and topramezone at 3.1 g ha-1. Siduron programs controlled smooth crabgrass and suppressed goosegrass while topramezone programs controlled goosegrass and suppressed smooth crabgrass. In laboratory and controlled-environment experiments, goosegrass absorbed three times more 14C than bermudagrass within 48 hours of 14C-topramezone treatment. Bermudagrass also metabolized topramezone twice as fast as goosegrass. Metribuzin admixture reduced absorption by 25% in both species. When herbicides were placed exclusively on soil, foliage, or soil plus foliage, topramezone controlled goosegrass only when applied to foliage and phytotoxicity of both bermudagrass and goosegrass was greater from topramezone than from metribuzin. Metribuzin was shown to reduce 21-d cumulative clipping weight and tiller production of both species while topramezone caused foliar discoloration to newly emerging leaves and shoots with only marginal clipping weight reduction. These data suggest that selectivity between bermudagrass and goosegrass is largely due to differential absorption and metabolism that reduces bermudagrass exposure to topramezone. Post-treatment irrigation likely reduces topramezone rate load with a concomitant effect on plant phytotoxicity of both species. Metribuzin admixture decreases white discoloration of bermudagrass by decreased topramezone absorption rate and eliminating new foliar growth that is more susceptible to discoloration by topramezone. / Doctor of Philosophy / Goosegrass and smooth crabgrass are problematic weeds in bermudagrass and creeping bentgrass turf. Increased incidences of herbicide resistant weed populations and severe use restrictions on formerly available herbicides have increased need for selective, postemergence control options for these weeds in creeping bentgrass and bermudagrass turf. Although potentially injurious, topramezone (Pylex™) can control these weeds, especially goosegrass, at low doses. Low-dose Pylex™ may also improve bermudagrass and creeping bentgrass response. An initial investigation evaluating tembotrione (Laudis®), Pylex™, and mesotrione (Tenacity®) in different turfgrass species showed that Kentucky bluegrass, perennial ryegrass, and tall fescue were highly tolerant to Pylex™ at rates ranging from 0.75 to 2.25 fl. oz./A, while creeping bentgrass and bermudagrass were low to moderately tolerant to Pylex™. Further investigation suggested that frequent, low-dose (less than 0.25 fl. oz./A) Pylex™ applications or metribuzin (Sencor®) admixtures could enhance weed control and may conserve turfgrass quality. A novel mixture of Pylex™ at 0.15 fl. oz./A and Sencor® at 4 oz. wt./A controlled goosegrass effectively and reduced bermudagrass injury to near acceptable levels and significantly less than Pylex™ applied alone at 0.25 fl. oz/A. In an attempt to further enhance bermudagrass tolerance to Pylex™, post-treatment irrigation was applied at different timings. When bermudagrass turf was irrigated at 15 or 30 minutes after herbicide treatment, bermudagrass injury was reduced to acceptable levels when following Pylex™ at 0.25 fl. oz./A plus Sencor® at 4 oz but not when following Pylex™ applied alone at 0.5 fl. oz./A. Goosegrass control was reduced significantly by post-treatment irrigation in all cases, while irrigation reduced goosegrass control by low-dose Pylex™ plus Sencor® to below-commercially-acceptable levels. Novel, low-dose, frequent application programs containing Pylex™ or siduron (Tupersan®) were developed for season-long crabgrass or goosegrass control in creeping bentgrass greens. Greens-height creeping bentgrass quality was preserved following five biweekly treatments of Tupersan® at rates between 6 and 24 lb./A and Pylex™ at 0.125 fl. oz./A. Tupersan® programs controlled smooth crabgrass and suppressed goosegrass while Pylex™ programs controlled goosegrass and suppressed smooth crabgrass. The data from these studies indicate that utilizing low-dose Pylex™ in combination with Sencor® can impart acceptable bermudagrass safety while also controlling goosegrass effectively. For creeping bentgrass greens, the low-dose, frequent application of Tupersan® is the safest legal option for golf course superintendents to control smooth crabgrass effectively, while having some ability to suppress goosegrass.
30

Análisis estructural de los productos derivados de cereales y su aplicación en la optimización de procesos y productos

Garzón Lloría, Raquel 24 May 2021 (has links)
[ES] La inspección visual es un parámetro de calidad que describe tanto el aspecto externo como la estructura interna en los productos derivados de cereales. El análisis digital de imagen (ADI) es una herramienta ampliamente utilizada en diversos campos para procesar y analizar los objetos que observamos visualmente. Sin embargo, a pesar de su potencial, ha sido escasamente explotado en el ámbito de alimentos. La estructura de la miga de los productos derivados de cereales es uno de los parámetros característicos del pan y en este contexto es fundamental realizar el seguimiento de los cambios estructurales que se producen durante el proceso o debido a las modificaciones en la formulación. Por ello, el objetivo principal de la presente tesis doctoral fue definir la interrelación entre la estructura y parámetros de calidad de masas y productos horneados, así como extender la utilidad del ADI y su uso para optimizar los procesos y las formulaciones en productos horneados. Para ello, en primer lugar, se establecieron las condiciones óptimas de captura y se estudió la forma de mejorar la detección de bordes. Posteriormente se evaluó el potencial del análisis de imagen para cuantificar los cambios estructurales ocurridos en la formación de geles de almidón en un analizador rápido de fuerza. Seguidamente, se estudió el impacto en la estructura de la adición o sustitución de distintos ingredientes o aditivos en panes con y sin gluten. Y finalmente se investigaron las posibles correlaciones entre los resultados obtenidos de la caracterización tecnológica (perfil de textura, estructura de la miga, humedad) frente a la percepción sensorial (propiedades del bolo, masticación y deglución). El ADI permitió cuantificar las diferentes estructuras obtenidas con los distintos almidones. Además, el estudio reveló las diferencias en el tiempo necesario para formar una estructura homogénea y bien distribuida, que fue dependiente del origen del almidón. La modificación de la formulación de panes con o sin gluten requirió de la adaptación del proceso y permitió obtener diferentes estructuras atendiendo a los ingredientes /aditivos estudiados. El ADI resultó ser una herramienta eficaz para detectar y cuantificar los cambios originados a nivel estructural, en masa y producto final. Además, los cambios cuantificados mediante ADI obtuvieron correlaciones estadísticamente significativas con varios de los parámetros estudiados de percepción sensorial, como son la adhesividad del bolo y el tiempo total para masticar y deglutir una muestra. Por lo tanto, el ADI resultó una herramienta suficientemente específica y no destructiva, que permitió caracterizar el impacto del cambio de la formulación en la distribución alveolar de panes con y sin gluten. Existiendo relación entre este y los parámetros utilizados habitualmente en la caracterización de productos derivados de cereales, así como con la percepción sensorial. / [CA] La inspecció visual és un paràmetre de qualitat que descriu tant l'aspecte extern com l'estructura interna en els productes derivats de cereals. L'anàlisi digital d'imatge (ADI) és una eina àmpliament utilitzada en diversos camps per a processar i analitzar els objectes que observem visualment. No obstant això, malgrat el seu potencial, ha sigut escassament explotat en l'àmbit d'aliments. L'estructura de la molla dels productes derivats de cereals és un dels paràmetres característics del pa i en aquest context és fonamental realitzar el seguiment dels canvis estructurals que es produeixen durant el procés o a causa de les modificacions en la formulació. Per això, l'objectiu principal de la present tesi doctoral va ser definir la interrelació entre l'estructura i paràmetres de qualitat dels diferents tipus de masses i productes enfornats, així com estendre la utilitat de l'ADI i el seu ús per a optimitzar els processos i les formulacions en productes enfornats. Per a això, en primer lloc, es van establir les condicions òptimes de captura i es va estudiar la manera de millorar la detecció de les vores. Posteriorment es va avaluar el potencial de l'anàlisi d'imatge per a quantificar els canvis estructurals ocorreguts en la formació de gels de midó en un analitzador ràpid de força. Seguidament, es va estudiar l'impacte en l'estructura de l'addició o substitució de diferents ingredients o additius en pans amb glútens i sense glútens. I finalment es van investigar les possibles correlacions entre els resultats obtinguts de la caracterització tecnològica (perfil de textura, estructura de la molla, humitat) enfront de la percepció sensorial (propietats del bol, masticació i deglució). L'ADI va permetre quantificar les diferents estructures obtingudes amb els diferents midons. A més, l'estudi va revelar les diferències en el temps necessari per a formar una estructura homogènia i ben distribuïda, que fou dependent de l'origen del midó. La modificació de la formulació de pans amb gluten o sense va requerir de l'adaptació del procés i va permetre obtindre diferents estructures atesos els ingredients /additius estudiats. L'ADI va resultar ser una eina eficaç per a detectar i quantificar els canvis originats a l'entorn estructural, en massa i producte final. A més, els canvis quantificats mitjançant ADI van obtindre correlacions estadísticament significatives amb els diversos paràmetres estudiats de percepció sensorial, com són l'adhesivitat del bol i el temps total per a mastegar i deglutir una mostra. Per tant, l'ADI va resultar una eina prou específica i no destructiva, que va permetre caracteritzar l'impacte del canvi de la formulació en la distribució alveolar de pans amb glutens i sense. Tot i existint relació entre aquest i els paràmetres utilitzats habitualment en la caracterització de productes derivats de cereals, així com amb la percepció sensorial. / [EN] Visual inspection is a quality parameter that describes both the external appearance as the internal structure in cereal-based products. Digital image analysis (DIA) is a tool widely used in several fields to process and analyse objects visually observed by the human eye. However, despite of its potential, it has been barely explored for food analysis purposes. Crumb structure in cereal-derived products is one of the most characteristic parameters in bread. Due to this, following up the structural changes caused by the process or by the formulation changes, is of fundamental importance. For that reason, the main target of this thesis was the definition of the relationship between the structure and the quality parameters of dough and baked products. Moreover, extending the DIA utility and its use to improve process and mixes in baked products represented other main objective of this work. To do that, first, the optimal capture conditions were established and the way to improve the edge detection was studied. Afterwards, image analysis was evaluated to quantify the structural changes that happened during the starch gels formation in a fast force analyser. Then, the impact on the structure by adding or replacing different ingredients or additives in gluten-free breads was studied. Finally, the possible correlations between the results obtained from technological characterization (texture profile, crumb structure, moisture content) versus sensory perception (bolus properties, chewing and swallowing) were also investigated. DIA allowed the quantification of the different structures obtained from different starches. In addition, the study revealed the differences in time needed to form a homogeneous and well-distributed structure, which was dependent on the origin of the starch. Formulation modification in bread with or without gluten required a process adjustment that allowed to obtain different structures depending on the ingredients / additives studied. DIA has been proved to be an effective tool for detecting and quantify changes originated at the structural, dough and final product levels. In addition, the changes quantified by DIA obtained statistically significant correlations with several parameters studied for the sensory perception, such as bolus adhesion and total time to chew and swallow the sample. Therefore, DIA was a sufficiently specific and non-destructive tool, which allowed to characterize the impact of the formulation change on the bread cell distribution with and without gluten. There being a relationship between this, and the parameters usually used in cereal products characterization, as well as sensory perception. / Authors acknowledge the financial support of the Spanish Ministry of Economy and Competitiveness (Projects AGL2011-23802 and AGL2014-52928-C2-1-R), the European Regional Development Fund (FEDER) and Generalitat Valenciana (Projects Prometeo 2012/064 and Prometeo 2017/189), the Spanish Ministry of Science, Innovation and Universities (RTI2018-095919-B-C21), and the European Regional Development Fund. This work is based upon the work from COST Action 18101 SOURDOMICS – Sourdough biotechnology network towards novel, healthier and sustainable food and bioprocesses, the European Regional Development Fund and the joint project between research group from IATA-CSIC and the research groups of Nutriomics and CIDPRO from Tecnologico de Monterrey, Mexico. / Garzón Lloría, R. (2021). Análisis estructural de los productos derivados de cereales y su aplicación en la optimización de procesos y productos [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/166856

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