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iv In recent years, outbreaks of infections associated with raw and minimally processed fruits and vegetables have been reported. Possible sources for contamination are irrigation water, manure, wash water, handling by workers and contact with contaminated surfaces. Pathogens can occur on raw and minimally processed produce at populations ranging from 103 to 109 CFU/g and able to survive and sometimes grow under various storage conditions. The objective of this study was to analyse the growth/survival of Salmonella Enteritidis at spot-inoculated or stem-injected cherry tomatoes during passive modified atmosphere packaging (MAP), controlled atmosphere (CA) and air storage at 7 and 22&deg / C. Low density polyethylene (LDPE) with a package size of 10x10 cm2 for 25&plusmn / 2 g tomatoes was used for MAP storage in which the gas composition equilibrated to 6% O2/ 4% CO2 and a carbon dioxide incubator was used for CA storage in which the CO2 level was monitored and maintained as 5% through the term of storage at 7 and 22&deg / C. During the research, the effect of ozone treatment (5-30 mg/L ozone gas for 0-20 min) was also considered for surface sanitation. The results demonstrate that S.Enteritidis can survive and/or grow during the storage of tomatoes depending on the location site of the pathogen on fruit, suspension cell density and storage temperature. During MAP, CA and air storage, S.Enteritidis with initial population of 7.0 log10 CFU/tomato survived on tomato surfaces with an approximate decrease of 4.0-5.0 log10 CFU/tomato in population within the storage period / however, in the case of initial population of 3.0 log10 CFU/tomato, cells died completely on day 4 during MAP storage and on day 6 during CA and air storage. The death rate of S.Enteritidis on the surfaces of tomatoes that were stored in MAP was faster than that of stored in air. Storage temperature was effective on the survival of S.Enteritidis for the samples stored at ambient atmosphere / cells died completely on day 6 at 7&deg / C and on day 8 at 22&deg / C. Stem scars provided protective environments for Salmonella / an approximate increase of 1.0 log10 CFU/tomato in stem-scar population was observed during MAP, CA and air storage at 22&deg / C within the period of 20 days. Cells survived with no significant change in number at 7&deg / C. The development of the microbial association in tomatoes was dominated by lactic acid bacteria (LAB). The pH values of the tomatoes changed approximately from 4.0 to 3.0 during the storage period. LAB grew well under all atmospheric conditions with or without the presence of S.Enteritidis. Gaseous ozone treatment has bactericidal effect on S.Enteritidis, inoculated on the surface of the tomatoes. 5 mg/L ozone gas treatment was not effective. 30 mg/L ozone gas treatment affected surface color.

Neste trabalho, foram desenvolvidos filmes finos de composição SrTi1-xFexO3 (0,00≤ x ≤0,150) nanoestruturados visando sua aplicação como sensor de gás ozônio. Os filmes finos foram depositados através da técnica de deposição por feixe de elétrons (EBD) cujo alvo utilizado foram pastilhas obtidas a partir do pó cristalino SrTi1-xFexO3 (0,00≤ x ≤0,150) sintetizadas através do método dos precursores poliméricos. Foi observado a partir das analises termogravimétrica e térmica diferencial que a incorporação de ferro no sistema diminui a temperatura de queima do pó precursor, sugerindo que o ferro atua como catalisador na cadeia polimérica. Os filmes depositados por DFE apresentam-se no estado amorfo sendo necessário um tratamento térmico ex-situ para que a fase cristalina desejada seja obtida. Todos os filmes apresentaram uma boa aderência aos diferentes tipos de substratos utilizados. Após o processo de cristalização, os filmes depositados sobre diferentes substratos foram caracterizados através das técnicas de difração de raios-X, espectroscopia UV-Vis e microscopia de força atômica (MFA). Foi observado que um aumento na temperatura de tratamento térmico dos filmes leva a um aumento no grau de cristalização e a uma diminuição no valor da energia de gap, calculada a partir dos espectros UV-VIS. A analise por MFA mostrou que a mudança do tipo de substrato utilizado não influencia as propriedades estruturais e microestruturais dos filmes. Através da realização de medidas de resistência elétrica, observou-se que os filmes cristalinos submetidos a um tratamento térmico ex-situ a 500oC por 4 horas apresentaram uma boa sensibilidade ao gás ozônio sendo possível detectar a presença de até 75 ppb de ozônio. / In this study, nanostructured thin films of SrTi1-xFexO3 (0.00 ≤ x ≤ 0.150) compositions were prepared looking their application as ozone gas sensor. The thin films were deposited using the technique of electron beam deposition (EBD) whose targets were obtained from polycrystalline SrTi1-xFexO3 (0.00 ≤ x ≤ 0.150) powders synthesized by the polymeric precursor method. It was observed from the thermogravimetric and differential thermal analysis that the incorporation of iron in the system decreases the calcination temperature of the precursor powders, suggesting that the iron acts as a catalyst in the polymer chain. The as obtained films deposited by EBD present an amorphous state being necessary a ex-situ heat treatment to obtain the desired crystalline phase. All films showed good adhesion to different substrates. After the crystallization process, the films deposited on different substrates were characterized through X-ray diffraction, UV-Vis spectroscopy and atomic force microscopy (AFM) trechniques. It was observed that an increase in the annealing temperature of the film results in an increase in the degree of crystallization and a decrease in the value of band gap energy, which was calculated from the UV-VIS spectra. The AFM analysis showed that changing the type of substrate does not influence the structural properties and microstructure of the films. By carrying out measurements of electrical resistance, it was observed that the crystalline films subjected to a ex-situ heat treatment at 500oC for 4 hours showed a good sensitivity to the ozone gas being possible to detect the presence of up to 75 ppb ozone.

Neste trabalho, foram desenvolvidos filmes finos de composição SrTi1-xFexO3 (0,00≤ x ≤0,150) nanoestruturados visando sua aplicação como sensor de gás ozônio. Os filmes finos foram depositados através da técnica de deposição por feixe de elétrons (EBD) cujo alvo utilizado foram pastilhas obtidas a partir do pó cristalino SrTi1-xFexO3 (0,00≤ x ≤0,150) sintetizadas através do método dos precursores poliméricos. Foi observado a partir das analises termogravimétrica e térmica diferencial que a incorporação de ferro no sistema diminui a temperatura de queima do pó precursor, sugerindo que o ferro atua como catalisador na cadeia polimérica. Os filmes depositados por DFE apresentam-se no estado amorfo sendo necessário um tratamento térmico ex-situ para que a fase cristalina desejada seja obtida. Todos os filmes apresentaram uma boa aderência aos diferentes tipos de substratos utilizados. Após o processo de cristalização, os filmes depositados sobre diferentes substratos foram caracterizados através das técnicas de difração de raios-X, espectroscopia UV-Vis e microscopia de força atômica (MFA). Foi observado que um aumento na temperatura de tratamento térmico dos filmes leva a um aumento no grau de cristalização e a uma diminuição no valor da energia de gap, calculada a partir dos espectros UV-VIS. A analise por MFA mostrou que a mudança do tipo de substrato utilizado não influencia as propriedades estruturais e microestruturais dos filmes. Através da realização de medidas de resistência elétrica, observou-se que os filmes cristalinos submetidos a um tratamento térmico ex-situ a 500oC por 4 horas apresentaram uma boa sensibilidade ao gás ozônio sendo possível detectar a presença de até 75 ppb de ozônio. / In this study, nanostructured thin films of SrTi1-xFexO3 (0.00 ≤ x ≤ 0.150) compositions were prepared looking their application as ozone gas sensor. The thin films were deposited using the technique of electron beam deposition (EBD) whose targets were obtained from polycrystalline SrTi1-xFexO3 (0.00 ≤ x ≤ 0.150) powders synthesized by the polymeric precursor method. It was observed from the thermogravimetric and differential thermal analysis that the incorporation of iron in the system decreases the calcination temperature of the precursor powders, suggesting that the iron acts as a catalyst in the polymer chain. The as obtained films deposited by EBD present an amorphous state being necessary a ex-situ heat treatment to obtain the desired crystalline phase. All films showed good adhesion to different substrates. After the crystallization process, the films deposited on different substrates were characterized through X-ray diffraction, UV-Vis spectroscopy and atomic force microscopy (AFM) trechniques. It was observed that an increase in the annealing temperature of the film results in an increase in the degree of crystallization and a decrease in the value of band gap energy, which was calculated from the UV-VIS spectra. The AFM analysis showed that changing the type of substrate does not influence the structural properties and microstructure of the films. By carrying out measurements of electrical resistance, it was observed that the crystalline films subjected to a ex-situ heat treatment at 500oC for 4 hours showed a good sensitivity to the ozone gas being possible to detect the presence of up to 75 ppb ozone.

This thesis is focused on the effect of ozone on ink-jet prints. The knowledge about print technologies, materials for ink-jet printing, influence of environmental factors on the prints degradation and the methods of print lifetime estimation are discussed in the theoretical part of the thesis. Test-charts of 108 samples of C, M, Y primary colours and their overprints were prepared. I used two types of papers designed for ink-jet printing. These samples were exposed the effect of ozone in various concentrations to perform an accelerated aging experiment. Optical density values, La*b* coordinates, colour difference values were calculated from the measured spectral data. Changes of colours of the ink due to ozone exposure were determined and discussed. The validity of the reciprocal law due to ozone exposure was studied, too. The reciprocal behaviour was not confirmed for both types of the studied papers.

In this diploma thesis the basic principles of inkjet print, ink composition, print media and degradation mechanisms of ink dyes are summarized. The thesis deals with study of varnish barrier properties in coloured inkjet prints. Permeability of water vapour and oxygen (parts of atmosphere) depending on different coatings are tested there. In addition the influence of ozone on degradation of dyes was studied, while ozone was permeating through barrier varnish layer of inkjet print. Ozone plays an important role in degradation processes of the inkjet prints and it also causes a gas-fading. Concentrations of acting ozone were established by iodometric titration. Simultaneously kinetics of degradation of Orange 7 was studied on indicator papers.

Submitted by Neusa Fagundes (neusa.fagundes@unioeste.br) on 2018-06-15T14:40:42Z No. of bitstreams: 2 Suian_Granella2018.pdf: 12037340 bytes, checksum: e79d50a23a20a18669ee3d99f5f048a2 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-06-15T14:40:42Z (GMT). No. of bitstreams: 2 Suian_Granella2018.pdf: 12037340 bytes, checksum: e79d50a23a20a18669ee3d99f5f048a2 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-02-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The development of seeds with high quality has demanded effective techniques throughout yield and trading chain, based on searching for increasingly technological procedures. Considering wheat as a source of essential energy in human and animal diet, and despite the occurrence of research advances on the production sector, further studies are needed to assure the safety of wheat seed quality. Thus, this trial aimed at studying the hygroscopicity of wheat seeds, and evaluating drying-ozonation process on kinetics of drying, total fungi counting and seeds physiological properties. Hygroscopic and thermodynamic properties were determined during water desorption in seeds for different psychrometric conditions of air, kinetics and thermodynamic properties of drying for different air temperatures and ozonation time. It was also evaluated the influence of ozone exposure time and air temperature during drying by the reduction of fungi and physiological properties (electrical conductivity, vigor and germination). It should be highlighted that the evaluations were repeated after 45 days of storage. The obtained results allowed the following conclusion: a) water content of wheat seeds balance was directly proportional to the relative humidity and decreases with the temperature increase to the same value of relative humidity, as it occurs for most hygroscopic products. Chung-Pfost was the model that best fitted to experimental data. The required energy (heat desorption isoteric) increased in order to remove water from the product due to water content decrease; b) Midili was the best model to represent the drying curves of wheat seeds. The effective diffusion coefficient increased as there was an increase on drying air temperature, whose values ranged from 6.1492×10−11 to 13.3568×10−11 m2 s−1 in drying period without ozone and from 6.8302×10−11 to 8.2668×10−11 on the drying-ozonation process. The activation energy showed values of 32.18 and 5.82 kJ mol-1, to drying with and without ozone, respectively. The thermodynamic properties (enthalpy and entropy) increased as the drying temperature increased; c) there was reduction on fungi as there was an increase on exposure time to ozone, and drying air temperature. Germination, vigor and electrical conductivity of wheat seeds were not significantly influenced by the time of exposure to ozone neither by the air drying temperature. Similar results were obtained after 45 days of storage. / O desenvolvimento de sementes de alta qualidade utiliza técnicas eficientes em toda cadeia de produção e comercialização, com a busca de procedimentos cada vez mais tecnológicos. Haja vista o trigo ser considerado uma fonte de energia essencial para a alimentação humana e animal, e apesar da ocorrência de avanços da pesquisa no setor de produção, são necessários estudos mais aprofundados na segurança da qualidade de sementes de trigo. Assim, objetivou-se, com este trabalho, estudar a higroscopicidade das sementes de trigo, e avaliar o processo de secagem-ozonização sobre a cinética de secagem, contagem de fungos total e propriedades fisiológicas das sementes. Foram determinadas as propriedades higroscópicas e termodinâmicas durante a dessorção da água nas sementes para diferentes condições psicrométricas do ar, a cinética e as propriedades termodinâmicas da secagem para diferentes temperaturas do ar e tempo de ozonização. Avaliaram-se também a influência do tempo de exposição ao ozônio e a temperatura do ar durante a secagem pela redução de fungos e propriedades fisiológicas (condutividade elétrica, vigor e germinação). As avaliações repetiram-se após 45 dias de armazenagem. Os resultados obtidos permitiram concluir que: a) o teor de água de equilíbrio das sementes de trigo foi diretamente proporcional à umidade relativa e decresceu com o aumento de temperatura para um mesmo valor de umidade relativa, como ocorre para a maioria dos produtos higroscópicos. E o Chung-Pfost foi o modelo que melhor se ajustou aos dados experimentais. O aumento da energia (calor isotérico de dessorção) necessária para retirar água do produto ocorreu devido à redução do teor de água; b) o modelo de Midilli foi o que melhor representou as curvas de secagem das sementes de trigo. O coeficiente de difusão efetivo aumentou com a elevação da temperatura do ar de secagem de 6,1492×10−11 para 13,3568×10−11 m2 s−1 na secagem sem ozônio e de 6,8302×10−11 para 8,2668×10−11 para o processo secagem-ozonização. A energia de ativação apresentou valores de 32,18 e 5,82 kJ mol-1, para a secagem com e sem ozônio, respectivamente. As propriedades termodinâmicas (entalpia e entropia) aumentaram com a elevação da temperatura de secagem; c) a redução de fungos aumentou com o acréscimo do tempo de exposição ao ozônio e temperatura do ar de secagem. As respostas para a germinação, o vigor e a condutividade eléctrica das sementes de trigo não foram influenciadas significativamente pelo tempo de exposição ao ozônio e nem pela temperatura do ar de secagem. Resultados semelhantes foram obtidos após a armazenagem por 45 dias.

Title from second page of PDF document. Includes bibliographical references (p. 144-152).

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