<p> The polymerization of styrene initiated with gamma radiation as well as thermal initiation was studied at temperatures, 150, 155, 160, 165, 180 and 200C and dose rates of 0.072-0.1836 M Rads/hour. In all cases the reactions were studied up to 100% conversion and the following results were obtained. (1) Rate of polymerization was independent of dose rate. (2) 165C was considered to be the temperature at which the radiation polymerization system in the case of styrene reaches a limiting rate of initiation caused by high temperature and dose rate. (3) Self-production of ethynylbenzene in the system at 200C probably caused retardation of the initial rate of polymerization. (4) No significant gel effect was observed in the investigated temperature range. (5) Polystyrene produced by radiation at high temperatures has a very low average molecular weight. (6) A general mechanism was proposed based on the characteristics of the reactions. (7) A temperature range was proposed as an optimal reaction temperature for radiation polymerization of styrene. </p> / Thesis / Master of Engineering (MEngr)

This report presents results from a series of experiments in which YAG samples (undoped, as well as doped with Nd and Cr3+) were exposed to ionizing radiation (gamma rays and UV). These experiments were performed for the purpose of investigating the various phtodarkening processes taking place in these materials in response to the ionizing radiation. The purpose of this investigation was to establish whether and how co-doping YAG with Cr3+ improves the material's resistance to photodarkening due to the ionizing radiation. The experiments tracked time-resolved transmittance of the samples at 1064 nm in immediate response a pulsed exposure to the ionizing radiation, as well as steady-state spectrally-resolved changed in the samples' optical absorption after the irradiation. The investigation revealed a number of photodarkening processes occurring in the samples in response to the ionizing radiation, both transient and permanent. It was further revealed that inclusion of Cr3+ ions in YAG significantly reduces these photodarkening processes, improving the material's radiation resistance. It was observed that materials containing at least 0.5 at% Cr3+ are essentially radiation-hardened, resisting both transient and steady-state changes in transmittance observed in the materials not containing Cr3+.

No description available.

Whey proteins are mainly a group of small globular proteins. Their structures can be modified by physical, chemical and other means to improve their functionality. The objectives of this study were to investigate the effect of radiation on protein-protein interaction, microstructure, and microbiological properties of whey protein-water solutions. Whey protein isolate (WPI) solutions (27-36% protein) were treated with different dosages (10-35 KGy) of gamma radiation. The protein solutions were analyzed for viscosity, turbidity, soluble nitrogen, total plate count, and yeast and mold counts. The interactions between whey proteins were also analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and scanning electron microscopy (SEM). The viscosity of protein solution (27%, w/w) was increased from 2.19 for the control to 4.78 mPa*s for the sample treated at 25 KGy, respectively, and viscosity also increased during storage at 23°C. The soluble nitrogen (10%, w/w) was decreased from 100% to 54.7% for control and the sample treated at 35 KGy. The effects of gamma radiation and storage time on viscosity of whey protein solutions were significant (p

Diversas alternativas têm sido buscadas para minimizar o impacto ambiental causado pelos polímeros convencionais. Uma importante alternativa é o uso de polímeros biodegradáveis; no entanto, em razão do seu custo elevado quando comparados com polímeros convencionais, surgiu à necessidade de desenvolver misturas poliméricas biodegradáveis utilizando aditivos naturais degradáveis, menos agressivos ao meio ambiente; os quais podem ser degradados pela ação de micro-organismos ou enzimas. Este trabalho teve como objetivo preparar blendas de amido termoplástico (thermoplastic starch, TPS) obtidos com glicerol, óleo de mamona (OM) e TWEEN&reg; 80 com poli(butileno adipato-co-tereftalato) (PBAT), por extrusão. Posteriormente as blendas foram submetidas ao processo de irradiação com dose de 25 kGy e caracterizadas por análises termogravimétrica (TGA); calorimetria exploratória diferencial por fluxo de calor (DSC); espectroscopia vibracional de absorção no infravermelho por transformada de Fourier (FTIR); microscopia eletrônica de varredura (MEV); difração de raios X (DRX) e índice de cristalinidade (IC). Os resultados mostraram maior degradabilidade térmica para as blendas F2 (compostas por OM) e F3 (compostas por OM e TWEEN&reg;80) em relação as blendas F0 (compostas por glicerol) e F1 (compostas por glicerol e TWEEN&reg; 80). Observou-se uma boa interação química entre os componentes das misturas e a sua miscibilidade parcial para as misturas F0 e F1, comparadas com as demais. No entanto, as misturas F2 e F3 não tiveram fases co-contínuas; sendo que as curvas padrões de DRX das amostras não foram alteradas pela radiação gama. Os IC tiveram alterações antes e após a irradiação de acordo com o plastificante utilizado. Assim, as amostras irradiadas e não irradiadas não tiveram suas propriedades alteradas nos testes realizados. Pôde-se concluir que é viável a substituição do óleo de mamona por glicerol em blendas de TPS/PBAT. / Several alternatives have been sought to minimize the environmental impact caused by conventional polymers. The use of biodegradable polymers is an important alternative for this; however, when compared to conventional polymers, the biodegradable ones have higher costs. Thus, the development of polymeric blends using matrices of biodegradable and synthetic polymers with natural additive, less environmentally aggressive materials that can be degraded by the action of microorganisms or enzymes, was considered. This work aimed to prepare blends of thermoplastic starch (TPS) obtained with glycerol, castor oil (OM) and TWEEN&reg; 80 with poly(butylene adipate-co-terephthalate) (PBAT) by extrusion. Posteriorly, the blends were submitted to the irradiation process at a dose of 25 kGy and characterized by thermogravimetric analysis (TGA); differential heat flow scanning calorimetry (DSC); Fourier transform infrared spectroscopy (FTIR); scanning electron microscopy (SEM); X-ray diffraction (XRD), and crystallinity index (CI). The results demonstrated increased thermal degradation for the F2 (composed by OM) and F3 (composed by OM and TWEEN&reg; 80) regarding F0 (composed by glycerol) e F1 (composed by glycerol and TWEEN&reg; 80) blends. A good blend component chemical interaction and partial miscibility for the blends F0 and F1 was observed and compared to the others. However, F2 and F3 blends did not present co-continuous phases; being that the XRD curve patterns were not altered by the gamma radiation. Changes in the crystallinity indexes (CI) were observed before and after irradiation according to the plasticizer used. The tests performed demonstrated that the irradiated and non-irradiated samples did not have their properties significantly altered. Thus, it was concluded that it is feasible to replace castor oil with glycerol in TPS/PBAT blends.

O amido é o mais abundante dos polissacarídeos de armazenamento de energia de plantas, usualmente depositado na forma de grânulos no citoplasma das células. Também é a principal fonte de energia para o homem, compondo 80-90% dos polissacarídeos da dieta humana, e é o principal responsável pelas propriedades tecnológicas que caracterizam grande parte dos produtos processados. O presente trabalho teve como objetivo a aplicação da ressonância paramagnética eletrônica (RPE) e espectroscopia de Infravermelho por transformada de Fourier (FTIR) ao estudo de amidos irradiados. Amostras em pó de dois amidos naturais, batata (bulbo) e milho (cereal) e farinha de mandioca fermentada ou polvilho azedo (raiz) foram submetidos à ação da radiação ionizante de fonte de 60Co Gammacell 220 com doses de 10, 20 e 30 kGy, taxa de dose de 1kGy h-1. Foram registrados e comparados os espectros de RPE dos três tipos de amidos irradiados e não irradiados. Os amidos apresentaram espectros de RPE semelhantes variando apenas na intensidade do sinal de radicais livres que acompanhou o incremento da dose. Foram estabelecidas as curvas de decaimento para cada um dos amidos ensaiados. No caso de amido de batata o decaimento do sinal apresentou excepcionalmente um comportamento linear quando a dose utilizada foi de 20 kGy. Foi obtido de maneira experimental o valor do fator g, que variou de 2,06062 a 1,94661, sendo o valor teórico g = 2,0023. Foram também estabelecidas as modificações radioinduzidas na estrutura molecular das amostras através da análise dos espectros de absorção no infravermelho por FTIR. / Starch is the most abundant plant energy storage polysaccharide, usually deposited in the form of granules in the cytoplasm of cells. It is also the main source of energy for man, making up 80-90% of polysaccharides in the human diet, and is mainly responsible for the technological properties that characterize most processed products. The present work aimed to the application of electronic paramagnetic resonance and Fourier Transform Infrared Spectroscopy to the study of irradiated starches. Powdered samples of two natural starches, potato (bulb) and corn (cereal) and fermented cassava flour or sour cassava (root) were subjected to the action of ionizing radiation from a 60Co Gammacell 220 at doses of 10, 20 and 30 kGy, dose rate of 1kGy h-1. The electronic paramagnetic resonance spectra of the three types of irradiated and non-irradiated starches were recorded and compared. The starches showed similar electronic paramagnetic resonance spectra varying only in the intensity of the free radical signal that accompanied the dose increase. The decay curves were established for each of the tested starches. In the case of potato starch, signal decay showed an exceptionally linear behavior when the dose used was 20 kGy. The value of factor g was obtained experimentally, ranging from 2.06062 to 1.94661, with the theoretical value g = 2.0023. The radioinduced modifications in the molecular structure of the samples were also established by the analysis of the infrared absorption spectra by Fourier Transform Infrared Spectroscopy.

A busca de uma vida mais saudável tem levado o consumidor a repensar seus hábitos alimentares, ingerir frutas e hortaliças em substituição a produtos industrializados, devido a isso, a demanda dos produtos minimamente processados tem evoluído rapidamente. O kiwi (Actinidia deliciosa) possui alto valor nutritivo, sendo rico principalmente em vitamina C, o qual apresenta grande aceitação nos mercados consumidores. Dessa forma, juntamente com o mamão, o maracujá e o abacaxi, o kiwi pode ser considerado como um recurso adicional de vitamina C na dieta, ou como substituto das frutas cítricas tradicionais. O objetivo deste trabalho foi avaliar os efeitos da radiação gama nas características físico-químicas de kiwis minimamente processados e armazenados sob refrigeração, uma vez que essa tecnologia aumenta a vida útil de prateleira de frutos e hortaliças. Os kiwis foram descascados, tratados e cortados em rodelas, armazenados em potes de polietileno de 10 cm de diâmetro por 6 cm de altura e irradiados nas doses de 0 (controle), 1 e 2 kGy, em fonte de 60Co Gammacell 220, com taxa de dose 0, 429 kGy/hora, no qual cada tratamento constou de 5 repetições com 15 rodelas de kiwis por repetição. Após irradiação as amostras foram armazenadas em câmara climática com temperatura de 6ºC (próxima à temperatura de geladeiras comerciais). Foram realizadas as seguintes análises físico-químicas: pH, cor, teor de clorofila, perda de massa fresca, umidade, ºBrix, acidez titulável e ácido ascórbico. O período de avaliações do kiwi foi 1º, 7º e 14º dia após a irradiação. Pelos resultados obtidos concluiu-se que a radiação gama não induziu mudanças prejudiciais nas propriedades fisico-químicas do kiwi, podendo ser utilizada para a conservação de frutos de kiwi minimamente processado o qual apresentou 7 dias de vida útil. / The search for a healthy life has led consumers to rethink their eating habits, consuming fruits and vegetables in place of manufactured products, therefore, the demand for minimally processed products has evolved rapidly. The kiwi fruit (Actinidia deliciosa) has high nutritional value, being rich in C vitamin especially, which has wide acceptance in consumer markets. Thus, along with papaya, passion fruit and pineapple, kiwi can be considered as an additional feature of C vitamin in the diet, or as a substitute for traditional citrus. The aim of this study was to assess the effects of gamma radiation on physical and chemical characteristics of kiwis minimally processed and stored under refrigeration, since this technology increases the shelf life of fruits and vegetables. The Kiwis was stripped, processed and cut into slices, stored in polyethylene bags of 10 cm squared and irradiated at doses of 0 (control), 1 and 2 kGy. A source of 60Co Gammacell 220, dose rate of 0.429 kGy/hour, in which each treatment had 5 replicates with 15 slices of kiwifruit per replicate. After irradiation the samples were stored in a climatic chamber at 6°C (near the temperature of commercial refrigerators). The following criteria were physicalchemical analysis: pH, color, chlorophyll content, loss of weight, moisture, acidity and Brix. The analysis were done on 1st, 7th and 14th days after irradiation. The results indicated that gamma radiation did not induce deleterious changes in the physicochemical properties of the kiwi may be used for preservation of minimally processed kiwifruit.

A ervilha é considerada uma fonte nutritiva de proteína vegetal de alta qualidade, sendo também reconhecida como boa fonte de vitaminas, minerais, compostos fenólicos e carboidratos. Considerando que nem todos os nutrientes presentes no alimento tornam-se acessíveis para absorção pelo organismo e considerando ainda que a irradiação é uma técnica que permite garantir a segurança e a qualidade de um alimento, controlando microrganismos patogênicos, sem afetar significativamente qualquer atributo organoléptico e sensorial, estudou-se comparativamente os efeitos gerados na bioacessibilidade de Fe e Zn, tomando como base, uma amostra controle, o processo tradicional de ervilhas congeladas e o processo utilizando radiação gama na dose de 1 kGy. As ervilhas foram avaliadas em duas condições de tempo: tempo inicial, correspondente ao tempo após o término do processamento e tempo após quinze dias de armazenamento. Verificou-se que para as amostras controle e irradiada, a bioacessibilidade do Fe foi inferior à das amostras congeladas. A bioacessibilidade do Zn para as amostras de ervilhas analisadas (controle, irradiada e congelada), apresentou um teor médio de 71%, de acordo com os testes estatísticos de ANOVA e Tukey, não houve diferença significativa entre as amostras. Este trabalho avaliou também os aspectos sensoriais (cor, textura e sabor), microbiológicos e a composição centesimal dos produtos obtidos por esses tratamentos. Nos aspectos sensoriais observou-se pela análise de variância (ANOVA) em um nível de significância de p>0,05, que não houve diferença significativa entre as amostras analisadas. Nos aspectos microbiológicos, para as análises de bolores e leveduras, contagem de aeróbios mesófilos, coliformes a 45°C, E. coli e Salmonella, verificou-se que a irradiação trouxe melhor preservação microbiológica às ervilhas quando comparadas com o congelamento e com as ervilhas apenas refrigeradas (controle). Em relação à composição centesimal, constatou-se que os resultados encontrados estão alinhados aos referenciados na literatura. / The pea is considered a nutritious source of high quality vegetable protein and is also recognized as a good source of vitamins, minerals, phenolic compounds and carbohydrates. Considering that not all the nutrients present in the food become accessible for absorption by the body, and also considering that irradiation is a technique that ensures the safety and quality of a food by controlling pathogenic microorganisms without significantly affecting any sensory attributes, this work evolved the effects generated in the bio accessibility of Fe and Zn. The study performed the comparison between the control sample (the traditional process of frozen peas) and those submitted to the process using gamma radiation at 1 kGy dose. The peas were evaluated in two conditions: initial time, corresponding to time after processing, and after fifteen days of storage. For both samples - control and the irradiated - the bioaccessibility of Fe was lower than that of the frozen samples. Considering the initial time and after 15 days of storage, the bioaccessibility of the Zn to the analyzed (control, irradiated and frozen) pea samples, was about 71% and according to the statistical tests of ANOVA and Tukey there was no difference between the samples. This work also evaluated the sensory aspects (color, texture and flavor), microbiological and the centesimal composition of the products obtained by these treatments. Sensory aspects presented no statistical differences among analyzed samples (p> 0.05). Microbiological aspects (for yeast and mold counts, aerobic mesophilic counts, Salmonella, coliforms organisms and Escherichia coli) demonstrated that the irradiation brought better microbiological preservation to the peas when compared with the freezing and the chilled peas (control). In relation to the centesimal composition, results found are in agreement with those referenced in the literature.

O presente trabalho teve como objetivos realizar um levantamento para identificar a entomofauna associada a rações na cidade São Paulo/SP bem como avaliar o efeito da radiação gama em rações para alimentação de animais domésticos infestadas por pragas. Amostras de 20 lojas Pet Shop de diferentes regiões da cidade São Paulo/SP foram submetidas a triagens de 1 e 45 dias para coleta de insetos com auxilio de aspirador entomológico e peneiras de diferentes granulometrias. As espécies Sitophilus zeamais, Cryptolestes ferrugineus, Lasioderma serricorne e Oryzaephilus sp. apresentaram maior freqüência. Na avaliação dos efeitos da radiação gama utilizamos amostras de grãos de milho, sementes de girassol e mistura para roedores infestadas com insetos adultos das espécies Sitophilus zeamais, Lasioderma serricorne e Plodia interpunctella, após o periodo de 7 a 10 dias foram retirados os insetos e as amostras submetidas a doses crescentes de radiação gama. As espécies Sitophilus zeamais e Lasioderma serricorne foram submetidas as doses de 0,25 a 1,50kGy e a espécie Plodia interpuctella a doses de 0,10 a 2,0kGy. Decorridos 40 dias após irradiação avaliou-se o número de insetos emergidos. Os resultados dos bioensaios com Sitophilus zeamais como com Lasioderma serricorne demostraram que doses apartir de 0,5 kGy foram suficientes para causar letalidade dos ovos e larvas recém emergidas. Os resultados com a Plodia interpunctella a partir de 1,50 kGy, não emergiram insetos adultos, concluindo-se que essas doses foram suficientes para causar letalidade dos ovos e larvas. / This study aimed to realize a survey to identify the associated insects to feed the city São Paulo / SP and also to assess the effect of gamma radiation on food ration for domestic animals infested by pests. Samples of 20 stores, \"Pet Shop\" in different regions in São Paulo / SP were subjected to trials of 1 and 45 days for collection of insects with the aid of plastic tray and screens of different sizes. The species Sitophilus zeamais, Cryptolestes ferrugineus, Lasioderma serricorne and Oryzaephilus sp. showed a higher frequency. In assessing the effects of gamma radiation we used samples of maize, sunflower seeds and mix for rodents infested with adults of the species Sitophilus zeamais, Lasioderma serricorne and Plodia interpunctella, after the period of 7 to 10 days the insects were removed and samples subjected to increasing doses of gamma radiation. The species Sitophilus zeamais and Lasioderma serricorne subjected doses from 0,25 to 1,50 kGy and species Plodia interpuctella doses from 0,10 to 2,0 kGy. After 40 days of irradiation was evaluated the number of insects emerged. The results of bioassays with Sitophilus zeamais and with Lasioderma serricorne demonstrated that doses starting at 0,5 kGy was sufficient to cause mortality of eggs and newly emerged larvae. The results with Plodia interpunctella from the 1,5 kGy, hasnt emerged adult insects, concluding that these doses were sufficient to cause mortality of eggs and larvae.

O presente trabalho teve como objetivo verificar e comparar o comportamento químico e físico-químico da manga cv. Tommy Atkins submetida aos tratamentos hidrotérmico e a irradiação nas doses 0,4 kGy e 1,0 kGy, a fim de complementar os estudos feitos por SABATO et al (2009) no teste de transporte real de mangas irradiadas do Brasil para o Canadá. Esses estudos permitiram comparar o desempenho da irradiação com o tratamento térmico quanto à preservação das características da manga destinada à exportação. Para tanto as mangas foram divididas em grupos: controle; banho térmico (46°C por 90 min); dose 0,4 kGy e dose 1,0 kGy. Os frutos foram mantidos em câmara fria (11°C ± 2) por 14 dias, e, posteriormente, a temperatura ambiente (23°C ±2) até o fim de sua vida útil. Durante o período de armazenamento a baixa temperatura, as análise foram realizadas em intervalos de 7 dias; e a cada 3 dias, quando mantidos a temperatura ambiente. Os resultados indicaram que a dose de 1,0 kGy foi o único grupo que manteve os frutos com a coloração da casca no estágio 3 durante todo período do experimento, porém promoveu uma maior perda de textura e degradação nos teores de acidez total titulável nos frutos ainda verdes. Notou-se que somente o grupo controle apresentou teores mais altos de ácido cítrico e succínico no último dia de experimento. Não houve diferenças significativas nos valores de sólidos solúveis totais, açúcares totais e avaliação de massa fresca em relação aos tratamentos avaliados. A análise de observação visual indicou que o grupo do banho térmico foi o que obteve o maior número de descarte dos frutos por decomposição com, aproximadamente, 55%. Concluiu-se que a irradiação é mais efetiva para a preservação da qualidade de mangas cv. Tommy Atkins, diminuindo o surgimento de podridões ou murchamento em relação ao tratamento térmico. Entretanto, a preservação da qualidade extrínseca do fruto não é concomitantemente influenciada pelas suas características intrínsecas, uma vez que, internamente, os frutos continuam seu amadurecimento normal, independente da dose aplicada. / The purpose of the present study was to verify and compare the chemical and physical-chemical behaviour of mango cv. Tommy Atkins subjected to hydrothermal treatment and irradiation at doses 0.4 and 1.0 kGy, to complement the studies by SABATO et al (2009) in the real transport of irradiated mangoes from Brazil to Canada. These studies allowed to compare the performance of irradiation with heat treatment on the preservation of the characteristics of mango for export. For these reason fruits were divided into groups: control, heat bath (46 ° C for 90 min), at dose 0.4 kGy and at dose 1.0 kGy. The fruits were stored at low temperature (11 ° C ± 2) for 14 days, and then at room temperature (23 ° C ± 2) until the end of its useful life. During the period of cold storage the analysis were performed at intervals of 7 days and every 3 days when kept at room temperature. The results indicated that the dose of 1.0 kGy was the only group that kept the fruit with the skin color on stage 3 throughout the experimental period, but provided a greater loss of texture degradation and the levels of total acidity in the fruits with green skin. It was noted that only the control group showed higher levels of citric acid and succinic acid in the last day of the experiment. There were no significant differences in soluble solids, total sugars and evaluation of weight in relation to treatments. The analysis of visual observation indicated that the heat bath group was the one with the highest number of fruit drop by decomposition with approximately 55%. It was concluded that irradiation is more effective in preserving the quality of mangoes cv. Tommy Atkins, reducing the appearance of rot or shriveling in relation to heat treatment. However, the preservation of the skin of fruit is not concurrently influenced by its intrinsic nature, since, internally, the fruits continue their normal maturation, independent of the applied dose.