O uso de nanomateriais em aplicações como catálise e medicina, despertou nos últimos anos o interesse no estudo das propriedades de nanoclusters. O estudo das propriedades termodinâmicas desses sistemas é essencial, pois mudanças estruturais originadas de mudanças de fase podem alterar propriedades como atividade catalítica, momento magnético e propriedades óticas. A dinâmica molecular vêm sendo utilizada para o estudo computacional das propriedades termodinâmicas de diversos nanomateriais, enquanto o uso de métodos de Monte Carlo (MC), nesse contexto, tem se restringido ao estudo de nanoclusters de Lennard-Jones (LJ). Para avaliar a viabilidade do uso de métodos de MC no estudo de propriedades de sistemas reais, uma implementação do método Parallel Tempering Monte Carlo (PTMC) utilizando algoritmos do estado da arte para realização de trocas, determinação de temperaturas e ajuste de deslocamentos foi construída. Através de testes, é mostrado que alguns dos algoritmos implementados podem não ser adequados ao estudo do problema em questão. A implementação foi validada com o estudo das propriedades termodinâmicas de nanoclusters de LJ com 38, 55 e 147 átomos, que possuem resultados conhecidos na literatura. Além disso, resultados para propriedades do nanocluster LJ98 são apresentados, e devido à características estruturais desse sistema, é observada uma transição sólido-sólido entre as estruturas tetraédricas e icosaédricas em temperatura abaixo da de fusão. A hipótese do uso do algoritmo PTMC para o estudo de propriedades de materiais reais, foi testada nas nanoligas (PtCo)55 e (PtNi)55, descritas pelo potencial de Gupta. Através da comparação das estruturas de mais baixa energia com resultados de teoria do funcional da densidade (DFT, do inglês), é mostrado que o uso do potencial de Gupta pode ser justificado, dados os baixos desvios no comprimento de ligação (menores que 2.4%) e a semelhança de outras características estruturais. Os resultados obtidos indicam que o método PTMC é capaz de identificar as mudanças de fase das nanoligas estudadas. Essas mudanças são ilustradas e analisadas com o uso de um algoritmo para a comparação da similaridade de estruturas, com o qual foi possível analisar a fusão dos nanoclusters Co55, Ni55, Pt30Co25 e Pt40Ni15 (obtida em temperaturas entre 900 e 1100 K); além da fusão, a 727 K, e transição sólido-sólido, a 300 K, para a Pt55. Com as estruturas mais frequentes, encontradas através da análise de similaridade, e com a realização de cálculos DFT, foi possível observar um deslocamento do centro da banda d em direção ao HOMO (Highest Occupied Molecular Orbital) causado pelo aumento da temperatura. Esse deslocamento, segundo o modelo da banda d válido para superfícies, pode indicar uma maior reatividade dos nanoclusters nesses casos. / The use of nanomaterials in applications such as catalysis and medicine, aroused in the last years interest in studying properties of nanoclusters. The study of thermodynamic properties of these systems is essential, since structural changes originated from phase changes can alter properties such as catalytic activity, magnetic moment and optical properties. Molecular dynamics have been used for the computational study of thermodynamic properties of various nanomaterials, while the use of Monte Carlo methods (MC), in this context, has been restricted to the study of Lennard-Jones (LJ) nanoclusters. To evaluate the feasibility of using MC methods to study properties of real systems, an implementation of the Parallel Tempering Monte Carlo (PTMC) method using state of the art algorithms to perform exchanges, determine the temperature set and adjust the maximum displacement, was built. Through testing, it is shown that some of the implemented algorithms may not be suitable for the study of the problem in question. The implementation was validated by studying the thermodynamic properties of LJ nanoclusters with 38, 55 and 147 atoms, which have results known in the literature. In addition, results for the properties of the LJ98 nanocluster are reported, and due to the structural features of this system, a solid-solid transition between the tetrahedral and icosahedral structures in a temperature below melting is observed. The possibility of using the PTMC algorithm in the study of properties of real materials, is tested in the (PtCo)55 and (PtNi)55 nanoalloys, described by the Gupta potential. By comparing the lowest energy structures with density functional theory (DFT) results, it is shown that the use of the Gupta potential can be justified, given the small deviation in the bond lenght (less than 2.4%) and the similarity of other structural features. The results indicate that the PTMC method is able to identify the phase changes in the studied nanoalloys. These changes are illustrated and analyzed with the use of an algorithm for comparing the structure similarity, which made possible the analysis of the melting of the Co55, Ni55, Pt30Co25 e Pt40Ni15 nanoclusters (obtained at temperatures between 900 e 1100 K); and the melting at 727 K, and solid-solid transition at 300 K, for Pt55. With the most frequent structures, obtained by the similarity analysis, and through DFT calculations, it was possible to observe a shift in the d band center to the HOMO (Highest Occupied Molecular Orbital) caused by the temperature increase. This shift, following the d band model valid for surfaces, may indicate a higher reactivity of the nanocluster in these cases.

O pinhão é a semente comestível da Araucaria angustifolia, sendo consumido no sul e sudeste do Brasil. Possui excelentes características nutritivas e energéticas. As sementes têm uma atividade de água muito elevada (>0,98), o que facilita o desenvolvimento de fungos durante a estocagem, dificultando a sua comercialização. A literatura sobre os seus aspectos nutricionais e tecnológicos é muito escassa. O objetivo principal deste trabalho foi determinar aspectos tecnológicos e de engenharia relacionados com o processamento e armazenamento do pinhão. Foi estudada a vida de prateleira do pinhão cru a 25°C (5 dias), 5°C (3 meses) e –18°C (mais de 8 meses) através de análises fisicoquímicas, microbiológicas e sensoriais. Foram propostas as seguintes operações preliminares para preservar a qualidade da semente comercializada: recepção, limpeza, seleção, classificação e armazenamento. Foram determinadas as isotermas de desorção do pinhão cru e cozido e de adsorção da farinha de pinhão cru em diferentes temperaturas (entre 10 e 40°C) sendo ajustados modelos da literatura e calculadas a entalpia e entropia diferenciais. Para os três casos o modelo que melhor se ajustou aos dados foi o de Chirife e a teoria compensatória foi aplicada. Foi avaliada também a cinética de secagem do pinhão cru e cozido em secador de bandeja a 55, 70 e 85°C. Os dados foram ajustados a modelos de secagem e calculadas as difusividades efetivas, sendo que a difusividade do pinhão cozido (1,18 a 3,17 x10-10 m2s-1) foi menor do que a do pinhão cru (1,64 a 4,52 x10-10 m2s-1), provavelmente devido à gelatinização do amido. Um dos processos empregados pela tecnologia de alimentos, com a finalidade de obter produtos estáveis a partir de sementes, é a produção de farinhas. Neste trabalho foi produzida farinha de pinhão variando as seguintes condições de processo: utilização de pinhão cru e cozido e diferentes temperaturas de secagem (55, 70 e 85°C). As farinhas produzidas com pinhão cozido apresentaram cor mais escura, com uma luminosidade menor (Lmédia= 75.8) e coordenada de cromaticidade maior (amédia= 6.9), quando comparadas com as farinhas de pinhão cru (Lmédia= 89.0, amédia= 2.1). A temperatura de secagem também influenciou a cor das farinhas produzidas com pinhão cru. Através de análise multivariada dos dados foi possível agrupar as amostras. A partir dos resultados da análise sensorial constatou-se que o suflê produzido com a farinha de pinhão cozido apresentou maior aceitação, obtendo-se um produto que une praticidade, inovação e apelo regional. Por último, como uma forma de aproveitamento da casca do pinhão, foi estudada a extração de compostos fenólicos da casca, como uma nova fonte de antioxidantes. Foram determinadas as melhores condições em termos de volume e concentração de solvente (etanol) e temperatura de extração, utilizando a metodologia de superfície de resposta. / The seeds of Araucaria angustifolia, named pinhão, are consumed in the South and Southeast of Brazil. Pinhão has good nutritious and energetic characteristics. Since the seeds have a high water activity (>0,98), they can be easily contaminated by mushrooms during the stockpiling, hindering its commercialisation. The literature about nutritional and technological aspects of pinhão is very scarce. The main objective of this work was to determine technological and engineering aspects of the processing and storage of pinhão. The Shelf life of raw pinhão was studied at 25°C (5 days), 5°C (3 months) and -18°C (more than 8 months) using physiochemical, microbiological and sensorial analyses. The following preliminary operations were proposed to preserve the quality of the seed for commercialisation: reception, cleaning, selection, classification and storage. Desorption of raw and cooked pinhão and adsorption isotherms of raw pinhão flour were determined at different temperatures (between 10 and 40°C), modelled using well know isotherm models and differential enthalpy and entropy were calculated. Results show that the Chirife model most appropriately represents the experimental data for the three cases and the enthalpy-entropy compensation theory was applied. Drying behavior of raw and cooked pinhão was studied at 55, 70 and 85°C. The data were adjusted to drying models and effective diffusivity were calculated. Values for cooked pinhão (1,18 to 3,17 x10-10 m2s-1) were smaller than values for raw pinhão (1,64 to 4,52 x10-10 m2s-1), probably due to starch gelatinisation. One of the processes used by food technology with the purpose of obtaining stable products from seeds, it is the production of flours. In this work pinhão flour was produced varying the following process conditions: use of raw or cooked pinhão and different drying temperatures (55, 70 and 85°C). Flours produced with cooked pinhão presented darker colour, with a smaller brightness (Lmean = 75.8) and larger coordinate of chromaticity (amean = 6.9), when compared with raw pinhão flours (Lmean = 89.0, amean = 2.1). Drying temperature also influenced the colour of flours produced with raw pinhão. Through multivariate analysis of the data it was possible to cluster the samples. Results of sensorial analysis show that soufflé produced with cooked pinhão flour presented larger acceptance, being obtained a new product with regional appeal. The extraction of phenolic compounds of pinhão coats was also studied as a new source of antioxidants. The best condition of solvent volume, ethanol concentration and temperature, using factorial design and response surface methodology, were obtained.

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2018-11-21T16:44:58Z No. of bitstreams: 1 2013 - Beatriz Autullo Ramos.pdf: 1610426 bytes, checksum: c3defc33414fda5b010152756fc0f0ce (MD5) / Made available in DSpace on 2018-11-21T16:45:00Z (GMT). No. of bitstreams: 1 2013 - Beatriz Autullo Ramos.pdf: 1610426 bytes, checksum: c3defc33414fda5b010152756fc0f0ce (MD5) Previous issue date: 2013-08-29 / CAPES / FAPERJ / The aim of this study was to obtain the sorption isotherms, analyze the kinetics of drying jatropha seeds, perform mathematical modeling of sorption isotherms and kinetic experiments, and to study the thermodynamics of the process. Seeds with initial moisture content of 8-10%, dry basis, were used. The sorption isotherms were found using two experimental devices: a water activity meter and a thermal bath with temperatures adjusted at 30, 40 and 50 ?C for the first apparatus and 40, 50 and 60 ?C for the second one. To obtain the sorption isotherms with a thermal bath the method of saturated saline solutions of MgCl2, K2CO3, KI, NaCl, and NaBrO3 was applied and the time to reach equilibrium was, generally, 20 days. Nine kinetic experiments were performed setting temperatures at 30, 40 and 50 ?C, and the superficial gas velocity at 397, 794 and 1190 cm/min, with duration of three hundred and sixty minutes. Oswin's mathematical model was the best to describe the hygroscopic behavior of the isotherms found with the water activity meter, while Caurie's model was the best for the thermal bath data, because they showed the lowest deviations and the highest coefficients of determination. ANOVA indicated that only the water activity has significant influence over the equilibrium moisture on the sorption isotherm experiments, in both equipments. Nine mathematical models were tested to simulate the kinetics and the ?two exponential terms? model presented the lowest deviations and highest coefficients of determination. It was observed that the temperature and superficial gas velocity did not significantly influence the kinetic experiments. For calculation of the thermodynamic properties the models that best fitted the data of the two experiments to obtain the sorption isotherms were used. The positive values of the differential enthalpy and entropy for both studies showed that the sorption process of jatropha seeds is endothermic and irreversible. The negative values of the Gibbs free energy variation for both studies indicated that the sorption process occurs spontaneously for the temperature conditions evaluated. The enthalpy-entropy compensation theory was applied satisfactorily and Krug?s test showed that the isokinetic temperature was different from the harmonic mean temperature in both studies. / O objetivo deste trabalho foi obter as isotermas de sor??o, analisar a cin?tica de secagem da semente do pinh?o-manso, realizar a modelagem matem?tica dos experimentos da isoterma de equil?brio e de cin?tica, e o estudo termodin?mico do processo. Utilizaram-se sementes com teor de umidade inicial de 8 a 10 %, em base seca. Os experimentos de determina??o da isoterma de equil?brio foram realizados utilizando dois equipamentos: o medidor de atividade de ?gua e o banho t?rmico, com faixas de temperatura de 30, 40 e 50 ?C, para o primeiro, e de 40, 50 e 60 ?C, para o segundo. As isotermas obtidas pelo banho t?rmico foram obtidas atrav?s do m?todo das solu??es salinas saturadas de MgCl2, K2CO3, KI, NaCl e NaBrO3 e o tempo para atingir o equil?brio foi, em geral, de 20 dias. Foram realizados nove experimentos de cin?tica, nas temperaturas de 30, 40 e 50 ?C, com velocidade superficial do g?s de 397, 794 e 1190 cm/min, com dura??o de trezentos e sessenta minutos. O melhor modelo matem?tico selecionado para descrever o comportamento higrosc?pico das isotermas foi o Oswin, para o medidor de atividade de ?gua, e o de Caurie, para o banho t?rmico, pois apresentaram os menores desvios e os maiores coeficientes de determina??o. Atrav?s da ANOVA verificou-se que somente a atividade de ?gua apresentou influencia significativa sobre a umidade de equil?brio para os experimentos de isoterma, em ambos os equipamentos. Nove modelos matem?ticos foram testados para a simula??o da cin?tica sendo que o modelo de ?Dois termos exponenciais? apresentou os menores desvios e os maiores coeficientes de determina??o. Observou-se que a temperatura e a velocidade superficial do g?s n?o influenciaram significativamente os experimentos de cin?tica. Para os c?lculos das propriedades termodin?micas foram utilizados os modelos que melhor ajustaram os dados dos dois experimentos para obten??o das isotermas de sor??o. Os valores positivos de entalpia e entropia diferencial, para ambos os estudos, mostraram que o processo de sor??o de ?gua nos gr?os de pinh?o-manso ? endot?rmico e irrevers?vel. Os valores negativos da varia??o da energia livre de Gibbs, para os dois estudos, indicaram que o processo de sor??o ocorre de forma espont?nea para as condi??es de temperatura avaliadas. A teoria compensat?ria entalpia-entropia foi aplicada de forma satisfat?ria, e o teste de Krug mostrou que a temperatura isocin?tica foi diferente da temperatura m?dia harm?nica nos dois estudos realizados.

Understanding of the interrelationship between structure, thermodynamic properties and phase diagrams is very useful for rationalizing the behavior of materials and development of predictive models, which can be used to optimize the composition of materials and their fabrication processes. The properties of materials are governed by its electronic and crystallographic structure. Chemical bonding determines the electronic structure of materials. Furthermore, the electronic structure plays a predominant role in determining the physical, electrical, magnetic, thermal and optical properties of materials. Crystal structure also influences most properties of materials. Since changes in thermodynamic variables such as temperature, pressure, and composition dramatically alter the physical properties of materials and its structure, it is desirable to study the thermodynamic stability of materials in conjunction with phase relations. Phase diagrams can indicate the ranges of pressure, temperature and chemical composition where specific phases and mixtures of phases are stable. If the Gibbs energies of all the phases involved are known, phase diagram can be computed using Gibbs energy minimization algorithms. In recent times, one of the important uses of thermodynamics in materials science has been in the computation of phase diagrams. To materials scientists phase diagrams are like maps to travelers. They guide the path through the composition space to find phases, fulfilling specific materials performance requirements. As phase diagrams are the graphic representations of minimizations of Gibbs energy under given constraints, computational thermodynamics significantly expands our capability to walk in the multi-component space of engineering materials. High-temperature phase-equilibrium studies, thermodynamics and materials processing have had a close relationship over a number of decades. Successful utilization of ceramic materials under different environmental conditions at high temperatures requires accurate thermodynamic data. Focus of the present investigation is to obtain correct phase relations and accurate thermodynamic data in selected technologically important ceramic oxide systems in which the data are either not available or are inconsistent. Based on the experimental data, different types of phase diagrams are computed for the systems of contemporary relevance. After a brief introduction, Chapter 1 discusses the brief overview of the experimental techniques available for determining the phase relations and thermodynamic properties at high temperatures and the methods used in this study. The chapter reviews the possible sources of errors in experimental techniques and tests for correct functioning. In Chapter 2, systematic studies on high-temperature phase equilibria and thermodynamic properties of compounds in the ternary systems Ln-Pd-O (Ln = La, Pr, Eu, Gd, Tb, Dy, Ho and Er) are presented. Some of the ternary oxides on the Ln-Pd-O systems have potential application in catalysis and electrochemistry. To optimize the parameters for the synthesis and to understand the behavior of the catalysts, it is useful to have information on the thermodynamic stability domain of each compound. Quantitative information on the stability of the ternary oxides is also useful for assessing the interaction of metal Pd with ceramic compounds containing rare-earth elements under different environments. Furthermore, the thermodynamic data are beneficial for the design of processes for the recovery of rare earth and precious metals from scrap. There is very little thermodynamic and phase diagram information on the Ln-Pd-O systems. Isothermal sections of phase diagram for the ternary system La-Pd-O at 1200 K and for the systems Ln-Pd-O (Ln = Pr, Eu, Gd, Tb, Dy, Ho and Er) at 1223 K, were established by the isothermal equilibration technique at high temperatures. Phases were identified after quenching by optical and scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive X-ray spectroscopy (EDS). Based on the phase relations, the thermodynamic properties of ternary interoxide compounds were determined by the solid-state galvanic cell technique over a range of temperature between 925 - 1400 K. An advanced version of the solid-state cell incorporating a buffer electrode was used for high temperature thermodynamic measurements. The function of the buffer electrode, placed between reference and working electrodes, was to absorb the electrochemical flux of the mobile species through the solid electrolyte caused by trace electronic conductivity. The buffer electrode prevented polarization of the measuring electrode and ensured accurate data. Yttria-stabilized zirconia was used as the solid electrolyte and pure oxygen gas at a pressure of 0.1 MPa as the reference electrode. These novel features enhanced the accuracy of thermodynamic data. From electrochemical measurements, the standard enthalpies of formation of these oxides from elements and their standard entropies at 298.15 K were also evaluated. The variation of the lattice parameters and unit cell volume as a function of rare earth atomic number for the three ternary compounds Ln4PdO7, Ln2PdO4 (Ln = La, Pr, Nd, Sm, Eu, Gd) and Ln2Pd2O5 (Ln = La to Er) are discussed. The systematic variations of thermodynamic properties of all the ternary compounds as a function of rare earth atomic number are presented and correlated with structural features. Thermodynamic and structural parameters of uninvestigated Ln-Pd-O systems (Ln = Ce, Pm) can be obtained by interpolation. Based on the thermodynamic information obtained in this study and auxiliary data on binary compounds available in the literature, different types of phase diagrams, isothermal oxygen potential diagrams, isobaric phase diagrams, isothermal two dimensional and three-dimensional chemical potential diagrams for the systems Ln-Pd-O (Ln = La, Pr, Eu, Gd, Tb, Dy, Ho and Er) are constructed. Chapter 3 contains the studies on partial phase diagrams of the systems M-Ru-O (M = Ca and Sr) at 1300 K and determination of Gibbs energies of formation of calcium and stronsium ruthenates in the temperature range from 925 to 1350 K using solid-state cells with yttria-stabilized zirconia as the electrolyte and Ru + RuO2 as the reference electrode. Gibbs energies, enthalpies and entropies of formation of calcium and strontium ruthenates from their component binary oxides were deduced. The standard enthalpies of formation of these oxides from elements and their standard entropies at 298.15 K were also evaluated. Based on the thermodynamic data obtained in this study and auxiliary information from the literature, the three dimensional representation of oxygen potential diagram for the M-Ru-O systems (M = Ca and Sr) as a function of composition and temperature are computed. The purpose of this chapter is to determine the thermodynamic stability of alkaline earth metal ruthenates in the perovskite related layered system Mn+1RunO3n+1 (n = 1, 2, and ¥ for Ca-Ru-O system and n = 1, 2, 3 and µ for Sr-Ru-O system) since these calcium and stronsium ruthenates have interesting magnetic and electronic device applications. Moreover, there is no literature available for thermodynamic properties on first and second members of the Ruddelsdon-Popper (R-P) series in Ca-Ru-O system, Ca2RuO4, Ca3Ru2O7 and third member of R-P series in Sr-Ru-O system, Sr4Ru3O10. Some of the available literature information on thermodynamic properties for other compounds of R-P series in Mn+1RunO3n+1 (M = Ca, Sr) are found to be based on incorrect assumptions and erroneous calculation. Thus, this chapter provides the complete thermodynamic information for all the electronically and magnetically applicable alkaline earth metal ruthenates for optimizing the deposition condition in device fabrications. Chapter 4 gives the structure-properties correlations of 2-3 spinel compounds and spinel-corundum equilibria for the system NiO-Al2O3-Cr2O3 at 1373 K. Nickel, aluminum and chromium are important base-constituent elements of high-temperature oxidation-resistant alloys. A spinel phase is usually found in the protective scale formed on the surface of the alloys. There is no thermodynamic data on spinel solid solution NiAl2O4-NiCr2O4. Thus, the phase relations and mixing properties of the spinel solid solution have been determined in this chapter. The inter-crystalline ion-exchange equilibrium between NiAl2+2xO4+3x-NiCr2O4 spinel solid solution and Al2O3-Cr2O3 solid solution with corundum structure in pseudo-ternary system NiO-Al2O3-Cr2O3 have been determined by the conventional tie-line rotation method at 1373 K. The nonstoichiometry of NiAl2+2xO4+3x has been taken into consideration. Lattice parameters were used to obtain the compositions of the corundum and spinel solid solutions at equilibrium. Formation of homogeneous solid solutions and attainment of equilibrium were confirmed by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS). From the experimental tie-line information and thermodynamic data on Al2O3-Cr2O3 solid solution available in the literature, the activities in the spinel solid solution were derived by using a modified Gibbs-Duhem integration technique. Gibbs energy of mixing of the spinel solid solution has been calculated from the derived activity data. Since high temperature data generation is expensive and time consuming, it is useful to develop models, which relate thermodynamic properties to electronic and crystallographic structure, leading to predictive modeling of mixing properties. By comparing the results from models with experimental information, one can evolve methodologies for the prediction of the properties of uninvestigated system. A model can be used to discriminate among conflicting experimental data and extrapolate the data into regions where direct measurements are lacking or difficult to perform. In this chapter, a model approach has also been considered to analyze the activity-composition relationship in the NiAl2O4-NiCr2O4 spinel solid solution in terms of the intra-crystalline exchange of cations between the tetrahedral and octahedral sites of the spinel structure governed by site preference energies of the cations. Since Ni2+ and Cr3+ ion in tetrahedral coordination exhibits Jahn-Teller distortion, an entropy corresponding to randomization of the distortion in the cubic phase has been incorporated in the cation distribution model. The thermodynamic mixing properties of stoichiometric spinel solid solution NiAl2O4-NiCr2O4 in terms of one mole of mixing species were computed at 1373 K. The strain energy caused by size mismatch was added as a separate term to the Gibbs energy of mixing using empirical relationship between enthalpy of mixing for a pair of ions and the difference in their ionic volumes. Madelung constant and electrostatic contribution of energy of mixing of the spinel solid solution have also been computed. Comparison of Gibbs energy of mixing calculated using the cation mixing model for the stoichiometric spinel solid solution NiAl2O4-NiCr2O4 with that of the experimental tie-line data for nonstoichiometric spinel solid solution NiAl2+2xO4+3x-NiCr2O4 were included in this chapter. The thermodynamic mixing properties obtained in this study would be helpful in understanding the formation of complex spinel protective layers on alloys containing nickel, aluminium and chromium in high-temperature applications. The summary of the important finding and the conclusions arrived at on the basis of results obtained from the present investigations are presented in Chapter 5.

O pinhão é a semente comestível da Araucaria angustifolia, sendo consumido no sul e sudeste do Brasil. Possui excelentes características nutritivas e energéticas. As sementes têm uma atividade de água muito elevada (>0,98), o que facilita o desenvolvimento de fungos durante a estocagem, dificultando a sua comercialização. A literatura sobre os seus aspectos nutricionais e tecnológicos é muito escassa. O objetivo principal deste trabalho foi determinar aspectos tecnológicos e de engenharia relacionados com o processamento e armazenamento do pinhão. Foi estudada a vida de prateleira do pinhão cru a 25°C (5 dias), 5°C (3 meses) e –18°C (mais de 8 meses) através de análises fisicoquímicas, microbiológicas e sensoriais. Foram propostas as seguintes operações preliminares para preservar a qualidade da semente comercializada: recepção, limpeza, seleção, classificação e armazenamento. Foram determinadas as isotermas de desorção do pinhão cru e cozido e de adsorção da farinha de pinhão cru em diferentes temperaturas (entre 10 e 40°C) sendo ajustados modelos da literatura e calculadas a entalpia e entropia diferenciais. Para os três casos o modelo que melhor se ajustou aos dados foi o de Chirife e a teoria compensatória foi aplicada. Foi avaliada também a cinética de secagem do pinhão cru e cozido em secador de bandeja a 55, 70 e 85°C. Os dados foram ajustados a modelos de secagem e calculadas as difusividades efetivas, sendo que a difusividade do pinhão cozido (1,18 a 3,17 x10-10 m2s-1) foi menor do que a do pinhão cru (1,64 a 4,52 x10-10 m2s-1), provavelmente devido à gelatinização do amido. Um dos processos empregados pela tecnologia de alimentos, com a finalidade de obter produtos estáveis a partir de sementes, é a produção de farinhas. Neste trabalho foi produzida farinha de pinhão variando as seguintes condições de processo: utilização de pinhão cru e cozido e diferentes temperaturas de secagem (55, 70 e 85°C). As farinhas produzidas com pinhão cozido apresentaram cor mais escura, com uma luminosidade menor (Lmédia= 75.8) e coordenada de cromaticidade maior (amédia= 6.9), quando comparadas com as farinhas de pinhão cru (Lmédia= 89.0, amédia= 2.1). A temperatura de secagem também influenciou a cor das farinhas produzidas com pinhão cru. Através de análise multivariada dos dados foi possível agrupar as amostras. A partir dos resultados da análise sensorial constatou-se que o suflê produzido com a farinha de pinhão cozido apresentou maior aceitação, obtendo-se um produto que une praticidade, inovação e apelo regional. Por último, como uma forma de aproveitamento da casca do pinhão, foi estudada a extração de compostos fenólicos da casca, como uma nova fonte de antioxidantes. Foram determinadas as melhores condições em termos de volume e concentração de solvente (etanol) e temperatura de extração, utilizando a metodologia de superfície de resposta. / The seeds of Araucaria angustifolia, named pinhão, are consumed in the South and Southeast of Brazil. Pinhão has good nutritious and energetic characteristics. Since the seeds have a high water activity (>0,98), they can be easily contaminated by mushrooms during the stockpiling, hindering its commercialisation. The literature about nutritional and technological aspects of pinhão is very scarce. The main objective of this work was to determine technological and engineering aspects of the processing and storage of pinhão. The Shelf life of raw pinhão was studied at 25°C (5 days), 5°C (3 months) and -18°C (more than 8 months) using physiochemical, microbiological and sensorial analyses. The following preliminary operations were proposed to preserve the quality of the seed for commercialisation: reception, cleaning, selection, classification and storage. Desorption of raw and cooked pinhão and adsorption isotherms of raw pinhão flour were determined at different temperatures (between 10 and 40°C), modelled using well know isotherm models and differential enthalpy and entropy were calculated. Results show that the Chirife model most appropriately represents the experimental data for the three cases and the enthalpy-entropy compensation theory was applied. Drying behavior of raw and cooked pinhão was studied at 55, 70 and 85°C. The data were adjusted to drying models and effective diffusivity were calculated. Values for cooked pinhão (1,18 to 3,17 x10-10 m2s-1) were smaller than values for raw pinhão (1,64 to 4,52 x10-10 m2s-1), probably due to starch gelatinisation. One of the processes used by food technology with the purpose of obtaining stable products from seeds, it is the production of flours. In this work pinhão flour was produced varying the following process conditions: use of raw or cooked pinhão and different drying temperatures (55, 70 and 85°C). Flours produced with cooked pinhão presented darker colour, with a smaller brightness (Lmean = 75.8) and larger coordinate of chromaticity (amean = 6.9), when compared with raw pinhão flours (Lmean = 89.0, amean = 2.1). Drying temperature also influenced the colour of flours produced with raw pinhão. Through multivariate analysis of the data it was possible to cluster the samples. Results of sensorial analysis show that soufflé produced with cooked pinhão flour presented larger acceptance, being obtained a new product with regional appeal. The extraction of phenolic compounds of pinhão coats was also studied as a new source of antioxidants. The best condition of solvent volume, ethanol concentration and temperature, using factorial design and response surface methodology, were obtained.

O pinhão é a semente comestível da Araucaria angustifolia, sendo consumido no sul e sudeste do Brasil. Possui excelentes características nutritivas e energéticas. As sementes têm uma atividade de água muito elevada (>0,98), o que facilita o desenvolvimento de fungos durante a estocagem, dificultando a sua comercialização. A literatura sobre os seus aspectos nutricionais e tecnológicos é muito escassa. O objetivo principal deste trabalho foi determinar aspectos tecnológicos e de engenharia relacionados com o processamento e armazenamento do pinhão. Foi estudada a vida de prateleira do pinhão cru a 25°C (5 dias), 5°C (3 meses) e –18°C (mais de 8 meses) através de análises fisicoquímicas, microbiológicas e sensoriais. Foram propostas as seguintes operações preliminares para preservar a qualidade da semente comercializada: recepção, limpeza, seleção, classificação e armazenamento. Foram determinadas as isotermas de desorção do pinhão cru e cozido e de adsorção da farinha de pinhão cru em diferentes temperaturas (entre 10 e 40°C) sendo ajustados modelos da literatura e calculadas a entalpia e entropia diferenciais. Para os três casos o modelo que melhor se ajustou aos dados foi o de Chirife e a teoria compensatória foi aplicada. Foi avaliada também a cinética de secagem do pinhão cru e cozido em secador de bandeja a 55, 70 e 85°C. Os dados foram ajustados a modelos de secagem e calculadas as difusividades efetivas, sendo que a difusividade do pinhão cozido (1,18 a 3,17 x10-10 m2s-1) foi menor do que a do pinhão cru (1,64 a 4,52 x10-10 m2s-1), provavelmente devido à gelatinização do amido. Um dos processos empregados pela tecnologia de alimentos, com a finalidade de obter produtos estáveis a partir de sementes, é a produção de farinhas. Neste trabalho foi produzida farinha de pinhão variando as seguintes condições de processo: utilização de pinhão cru e cozido e diferentes temperaturas de secagem (55, 70 e 85°C). As farinhas produzidas com pinhão cozido apresentaram cor mais escura, com uma luminosidade menor (Lmédia= 75.8) e coordenada de cromaticidade maior (amédia= 6.9), quando comparadas com as farinhas de pinhão cru (Lmédia= 89.0, amédia= 2.1). A temperatura de secagem também influenciou a cor das farinhas produzidas com pinhão cru. Através de análise multivariada dos dados foi possível agrupar as amostras. A partir dos resultados da análise sensorial constatou-se que o suflê produzido com a farinha de pinhão cozido apresentou maior aceitação, obtendo-se um produto que une praticidade, inovação e apelo regional. Por último, como uma forma de aproveitamento da casca do pinhão, foi estudada a extração de compostos fenólicos da casca, como uma nova fonte de antioxidantes. Foram determinadas as melhores condições em termos de volume e concentração de solvente (etanol) e temperatura de extração, utilizando a metodologia de superfície de resposta. / The seeds of Araucaria angustifolia, named pinhão, are consumed in the South and Southeast of Brazil. Pinhão has good nutritious and energetic characteristics. Since the seeds have a high water activity (>0,98), they can be easily contaminated by mushrooms during the stockpiling, hindering its commercialisation. The literature about nutritional and technological aspects of pinhão is very scarce. The main objective of this work was to determine technological and engineering aspects of the processing and storage of pinhão. The Shelf life of raw pinhão was studied at 25°C (5 days), 5°C (3 months) and -18°C (more than 8 months) using physiochemical, microbiological and sensorial analyses. The following preliminary operations were proposed to preserve the quality of the seed for commercialisation: reception, cleaning, selection, classification and storage. Desorption of raw and cooked pinhão and adsorption isotherms of raw pinhão flour were determined at different temperatures (between 10 and 40°C), modelled using well know isotherm models and differential enthalpy and entropy were calculated. Results show that the Chirife model most appropriately represents the experimental data for the three cases and the enthalpy-entropy compensation theory was applied. Drying behavior of raw and cooked pinhão was studied at 55, 70 and 85°C. The data were adjusted to drying models and effective diffusivity were calculated. Values for cooked pinhão (1,18 to 3,17 x10-10 m2s-1) were smaller than values for raw pinhão (1,64 to 4,52 x10-10 m2s-1), probably due to starch gelatinisation. One of the processes used by food technology with the purpose of obtaining stable products from seeds, it is the production of flours. In this work pinhão flour was produced varying the following process conditions: use of raw or cooked pinhão and different drying temperatures (55, 70 and 85°C). Flours produced with cooked pinhão presented darker colour, with a smaller brightness (Lmean = 75.8) and larger coordinate of chromaticity (amean = 6.9), when compared with raw pinhão flours (Lmean = 89.0, amean = 2.1). Drying temperature also influenced the colour of flours produced with raw pinhão. Through multivariate analysis of the data it was possible to cluster the samples. Results of sensorial analysis show that soufflé produced with cooked pinhão flour presented larger acceptance, being obtained a new product with regional appeal. The extraction of phenolic compounds of pinhão coats was also studied as a new source of antioxidants. The best condition of solvent volume, ethanol concentration and temperature, using factorial design and response surface methodology, were obtained.

Com o aumento do uso do método de síntese por combustão em solução para obtenção de pós cerâmicos, há uma crescente percepção da necessidade de se entender as características únicas deste processo. Esta tese apresenta uma investigação baseada na obtenção de diferentes pós nanoestruturados: Al2O3-α (alumina), Cr2O3 (crômia), Fe2O3-α (hematita), Fe3O4 (magnetita), NiO (bunsenita) e CoO, Co3O4 (óxidos de cobalto), como opção para futuras aplicações. Estes foram caracterizados via ATD, BET, DRX, MET, MEV, VSM, XPS e FTIR. O foco particular deste trabalho é o estudo da razão combustível-oxidante e sua influência nas características dos materiais resultantes. Outros parâmetros de combustão foram identificados e também devidamente avaliados, tais como: tipo de chama, temperatura, gases gerados e composição química dos reagentes precursores. O cálculo termodinâmico da reação de combustão em solução mostrou que, quando a razão combustível-oxidante aumenta, obtêm-se uma elevação da temperatura de chama adiabática e da quantidade de gás produzida, definindo características do particulado como morfologia, tamanho de cristalito, área superficial e nível de agregação. A formação dos óxidos e metais seguiu um comportamento termodinâmico esperado, conforme energia livre de Gibbs. Menores tamanhos de cristalito foram obtidos sempre na condição deficiente em combustível para todos os sistemas estudados. Já a temperatura foi o principal parâmetro de reação que governou a taxa de crescimento e concorreu com a geração de gases para a formação dos cristalitos em certas condições redutoras. Os resultados deste trabalho melhoraram significativamente o entendimento do efeito da razão combustível-oxidante no comportamento das características físicas dos pós. Esta correlação foi avaliada com intuito de fornecer base de conhecimento para possível aplicação desta tecnologia na otimização ou desenvolvimento de novos sistemas de pós. / With the increasing use of solution combustion synthesis method for powder obtaining, there is a growing realization of the need to understand the unique characteristics of this process. This thesis presents the novel investigation of this technique specifically based upon some nanostructured powders such as α - Al2O3 (alumina), Cr2O3 (eskolite), α - Fe2O3 (hematite), Fe3O4 (magnetite), NiO (bunsenite), and CoO, Co3O4 (cobalt oxides) as a core option for future applications. These were characterized via DTA, BET, XRD, TEM, SEM, VSM, XPS, and FTIR. The particular focus of this work is based on the study of the fuel-to-oxidant ratio influence to the characteristics of the resulting materials. Other combustion parameters were identified and also proper appraised as flame type, temperature, gas generation, and chemical composition of precursor reagents. The thermodynamic calculation of the combustion reaction shows that as fuel-tooxidant ratio increases the amount of gas produced, and adiabatic flame temperature also increases. Powder characteristics as morphology, crystallite size, surface area and aggregation degree are mainly governed by the flame temperature, and generation of gases. The oxide and metals formation followed a thermodynamic behavior as expected, conform to Gibbs free energy. Lower crystallite sizes were always obtained by fuel-lean condition for all studied systems. The temperature was the main reaction parameter controlling the growth rate, while it competed with generation of gases to form crystallites under certain reducing conditions. The outcomes of this work have significantly improved the understanding of the fuelto- oxidant ratio effects on the behavior of the physical characteristics of powders. This correlation has been drawn in order to provide a knowledge basis for possible application of this technology to optimize or develop new powder systems.

Com o aumento do uso do método de síntese por combustão em solução para obtenção de pós cerâmicos, há uma crescente percepção da necessidade de se entender as características únicas deste processo. Esta tese apresenta uma investigação baseada na obtenção de diferentes pós nanoestruturados: Al2O3-α (alumina), Cr2O3 (crômia), Fe2O3-α (hematita), Fe3O4 (magnetita), NiO (bunsenita) e CoO, Co3O4 (óxidos de cobalto), como opção para futuras aplicações. Estes foram caracterizados via ATD, BET, DRX, MET, MEV, VSM, XPS e FTIR. O foco particular deste trabalho é o estudo da razão combustível-oxidante e sua influência nas características dos materiais resultantes. Outros parâmetros de combustão foram identificados e também devidamente avaliados, tais como: tipo de chama, temperatura, gases gerados e composição química dos reagentes precursores. O cálculo termodinâmico da reação de combustão em solução mostrou que, quando a razão combustível-oxidante aumenta, obtêm-se uma elevação da temperatura de chama adiabática e da quantidade de gás produzida, definindo características do particulado como morfologia, tamanho de cristalito, área superficial e nível de agregação. A formação dos óxidos e metais seguiu um comportamento termodinâmico esperado, conforme energia livre de Gibbs. Menores tamanhos de cristalito foram obtidos sempre na condição deficiente em combustível para todos os sistemas estudados. Já a temperatura foi o principal parâmetro de reação que governou a taxa de crescimento e concorreu com a geração de gases para a formação dos cristalitos em certas condições redutoras. Os resultados deste trabalho melhoraram significativamente o entendimento do efeito da razão combustível-oxidante no comportamento das características físicas dos pós. Esta correlação foi avaliada com intuito de fornecer base de conhecimento para possível aplicação desta tecnologia na otimização ou desenvolvimento de novos sistemas de pós. / With the increasing use of solution combustion synthesis method for powder obtaining, there is a growing realization of the need to understand the unique characteristics of this process. This thesis presents the novel investigation of this technique specifically based upon some nanostructured powders such as α - Al2O3 (alumina), Cr2O3 (eskolite), α - Fe2O3 (hematite), Fe3O4 (magnetite), NiO (bunsenite), and CoO, Co3O4 (cobalt oxides) as a core option for future applications. These were characterized via DTA, BET, XRD, TEM, SEM, VSM, XPS, and FTIR. The particular focus of this work is based on the study of the fuel-to-oxidant ratio influence to the characteristics of the resulting materials. Other combustion parameters were identified and also proper appraised as flame type, temperature, gas generation, and chemical composition of precursor reagents. The thermodynamic calculation of the combustion reaction shows that as fuel-tooxidant ratio increases the amount of gas produced, and adiabatic flame temperature also increases. Powder characteristics as morphology, crystallite size, surface area and aggregation degree are mainly governed by the flame temperature, and generation of gases. The oxide and metals formation followed a thermodynamic behavior as expected, conform to Gibbs free energy. Lower crystallite sizes were always obtained by fuel-lean condition for all studied systems. The temperature was the main reaction parameter controlling the growth rate, while it competed with generation of gases to form crystallites under certain reducing conditions. The outcomes of this work have significantly improved the understanding of the fuelto- oxidant ratio effects on the behavior of the physical characteristics of powders. This correlation has been drawn in order to provide a knowledge basis for possible application of this technology to optimize or develop new powder systems.

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