In this work, the phase behavior of binary systems comprising nitrogen and a noble element (nitrogen + argon and nitrogen + krypton) was studied at high density in the condensed state. Following the work of Lotz et al.[2001], the main goal of this work was to further investigate the pressure-concentration phase diagram as well as to look for the possible formation of van der Waals compounds at elevated pressures and room temperature and study their physical properties, using both vibrational spectroscopy and X-ray diffraction. The observed phases, formed by single atoms and/or simple molecules in the binary systems were solved and modeled for their corresponding crystalline structures. From experimental results, lattice parameters for all crystalline structures and phase transitions, if detected, have been observed to shift with respect to that of the pure substances. The analyses and characterization of these binary systems are discussed in detail.

An objective analytical method was developed to characterize the taste profiles of five cheese varieties. Nonvolatile water extracts of Cheddar, Edam, Gouda, Swiss, and Parmesan cheeses were analyzed by high performance liquid chromatography (HPLC) with a reversed phase column. The HPLC operating conditions were determined with Mapping Super-Simplex followed by Centroid Mapping Optimization. A ternary gradient elution system was used with an Adsorbosphere C8 column to resolve a maximum number of components. The optimum solvent volume ratio was 96.8 : 1.2 : 2.0 for trifluoroacetic acid (0.1%), acetonitrile, and methanol, with a flow rate of 1.0 mL/min. Over 50.3 min this ratio was changed to 56.3 : 30.3 : 13.4. Multivariate statistical analyses including principal component and discriminant analyses were applied to 55 peak areas from 106 cheese chromatograms. Principal component analysis reduced the dimensionality of the "data from 55 to 17 principal components, which are-combinations of the original variables, with a 26% loss of explained sample variation. Discriminant analysis on data from a single HPLC column was able to correctly classify cheeses by variety at a greater than 90% success rate. This grouping rate dropped to 64% when data from all four HPLC columns was combined, implicating large between column variations. A semi-trained sensory panel correctly classified cheeses by variety at a 63% rate. This objective method provides a lasting fingerprint of cheese products. / Land and Food Systems, Faculty of / Graduate

Orientadores: Narcizo Marques de Souza Neto, Flávio César Guimarães Gandra / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-26T19:21:43Z (GMT). No. of bitstreams: 1 Reis_RicardoDonizethdos_D.pdf: 10140891 bytes, checksum: 060b8807511ae67be03dba829dddacaf (MD5) Previous issue date: 2015 / Resumo: Os resultados apresentados nesta tese mostram a potencialidade do uso das técnicas de espectroscopia de absorção de raio X no estudo das hibridizações (4f,5f )/(5d,6d) em compostos intermetálicos ajudando no entendimento de diversos fenômenos físicos. Na primeira parte do trabalho utilizamos as técnicas de espectroscopia para estudar o comportamento da valência e do magnetismo no composto de EuPt2Si2 quando submetido à pressão. Ao contrário do previamente reportado na literatura nossos resultados mostram que o composto de EuPt2Si2, encontra-se nas vizinhanças de um ponto crítico quântico de flutuação de valência, e a valência do íon de Eu, que é de 2.2 ã pressão ambiente, aumenta com o incremento da pressão se tornando 3+ para pressões maiores do que 15 GPa. A mudança de valência diminuiu o número de íons magnéticos da amostra o que provoca um colapso do seu momento magnético. Nossos dados suportados por cálculos de densidade de estados eletrônicos mostram que o processo de transição de valência ocorre com uma transferência de carga entre os níveis 4f e 5d do Európio, acompanhado de uma maior localização dos orbitais 5d do Eu, fazendo com que as cargas inicialmente compartilhadas pelos íons de Eu/Pt/Si se localizem no orbital 5d do Eu. Na segunda parte desta tese nós mostramos, até nosso conhecimento, os primeiros resultados de dicroísmo circular magnético de raios X (XMCD) nas bordas L2,3 do Urânio. Foram estudados os compostos de UM2(M=Ga,Ge) e UX(X=Te,Se) para os quais foi observada uma gigante contribuição quadrupolar nos espectros de dicroísmo na borda L3. Descrevemos uma metodologia associando a técnica de dicroísmo circular magnético com simulações da estrutura eletrônica usando teoria do funcional densidade (DFT), para estudar o grau de hibridização entre os orbitais 5f-6d e obter informações a respeito do caráter itinerante/localizado do magnetismo de cada um dos compostos. Por fim, a seletividade ao elemento químico da técnica de XMCD foi aplicada no estudo do magnetismo dos compostos de UCu2Si2 e UMn2Si2. A partir dos espectros de XMCD nas bordas L3 do Urânio e K do Cu e do Mn, mostramos que ao contrário do previamente reportado na literatura, tanto o Urânio como os metais 3d nesses materiais apresentam um momento magnético não nulo e que as hibridizações entre os níveis 5f e 3d regulam as propriedades magnéticas nestes dois materiais. Além disso, mostramos que no composto UCu2Si2 o momento magnético oriundo dos níveis 5f (contribuição quadrupolar do XMCD) é antiparalelo ao momento dos níveis 6d (contribuição dipolar do XMCD) / Abstract: The results reported in this thesis show the potential for the use of X-ray Absorption Spectroscopy (XAS) technique on the study of (4f,5f )/(5d,6d) hybridization in intermetallic compounds aiding the understanding of many physical phenomena. On the first part of this thesis, in order to probe the changes in the valence state and magnetic properties of EuPt2Si2 compound under extreme pressure, x-ray absorption near-edge spectroscopy (XANES) and x-ray magnetic circular dichroism (XMCD) were carried out. The XANES spectrum exhibitx a strong dependence with temperature and pressure. Contrary to previous reports, Eu was found to change the valence with the increase of the pressure from divalent to the trivalent state. The change in valence reduced the number of magnetic ions of the sample which causes a collapse of its magnetic moment. Density functional theory has been applied to give insight into the pressure-induced changes in Eu valence and the magnetic ordering on this compound. In the second part of this thesis we show, to the best of our knowledge, the first results of magnetic circular dichroism in Uranium L2,3 edges. A giant quadrupolar contribution was observed in U-L2,3 edges x-ray magnetic circular dichroism of a few representative Uranium compounds (UGa2, UGe2, UTe and USe). We support the spectroscopic data with density functional theory to assess the degree of 5f -6d electronic hybridization and the degree of itineracy/localization of 5f electrons in each of the compounds. Finally, we use the element and orbital selectivity of XANES and XMCD measurements combined on U-L3 and Cu and Mn K absorption edges to probe the eletronic and magnetic properties of the UMn2Si2 and UCu2Si2 compounds. Our results show that both Uranium and 3d elements present magnetic moment and therefore the 5f /3d hybridization regulates the magnetic properties on these compounds. Furthermore, we show for UCu2Si2 compound the aligment of magnetic moments of U 5f and U 6d orbitals is antiparallel / Doutorado / Física / Doutor em Ciências

Orientadores: Denis José Schiozer, Otto Luiz Alcântara Santos / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica e Instituto de Geociências / Made available in DSpace on 2018-08-28T00:50:08Z (GMT). No. of bitstreams: 1 Correia_CatarinadeBarros_M.pdf: 39709375 bytes, checksum: f340649615835b8ee6394fd81de2034f (MD5) Previous issue date: 2015 / Resumo: Para estimar a pressão de poros, é necessário entender os mecanismos pelos quais ela foi gerada. Dentre aqueles capazes de gerar alta pressão de poros (sobrepressão), um tem sido apontado na literatura como o mais comum, a subcompactação, entretanto, outros mecanismos, como aqueles causadores de descarregamento, podem atuar. A não identificação da sobrepressão ou a desconsideração dos efeitos causados pelos mecanismos atuantes podem resultar em erros significativos ao estimar a pressão de poros antes da perfuração. A consequência (pressão real maior que a pressão de poros estimada) pode revelar, na prática, estreitamento da janela operacional durante a perfuração, deteriorando a segurança por levar a complicadores como instabilidade das paredes do poço, kicks, perdas de circulação, dano aos revestimentos etc. Este trabalho propõe a análise crítica e aplicação de dois métodos de estimativas de pressão de poros, Eaton (1975) e Bowers (1995), discutindo suas principais premissas, vantagens e limitações, levando em conta uma sistemática de trabalho considerada compatível com o estado da arte usado em companhias de petróleo internacionais. O primeiro se baseia na ocorrência de subcompactação de formações argilosas, sua utilização é consagrada pela indústria de petróleo e suas equações são as mais utilizadas em simuladores comerciais. O segundo propõe um método gráfico para investigação da co-atuação de outros mecanismos geradores de sobrepressão. Os dois métodos foram avaliados pela estimativa de pressão de poros usando a velocidade intervalar da sísmica e perfis elétricos de poços de dois campos de petróleo em águas profundas da Bacia de Sergipe ¿ Alagoas, com foco no Cretáceo Superior da Formação Calumbi. Os resultados gerados foram analisados e comparados com os dados de pressão medida, sobretudo no Maastrichtiano e no Campaniano, mostrando, em geral, correlação muito boa ou boa nessas idades geológicas, dentro dos parâmetros de qualidade estabelecidos. Foi demonstrado, entretanto, que o Método de Eaton (aplicado, previamente, para entender o comportamento das pressões nos campos), mesmo face às limitações envolvidas, é mais simples, fácil de aplicar e de calibrar e menos dependente de medidas pontuais de perfis de leitura de porosidade para geração de curvas de pressão de poros que o Método de Bowers. Este último se mostrou instável, com exigências de aplicação e dependente de parâmetros que não tornam seu uso tão amplo, fácil e simples de interpretar quanto o de Eaton, mesmo em áreas não exploratórias / Abstract: An understanding of pressure generating mechanisms is necessary when predicting pore pressure, the mainstay of any well drilling project. Undercompaction of clay rich sediments is the most commonly cited mechanism. However, a number of others, such as those related to fluid expansion, have been proposed as capable of generating overpressures. Failure to identify or ignore the overpressure or the active mechanism may result in significant errors in pore pressure estimation. The consequence (real pressure higher than the estimated pressure) deteriorates the drilling safety, narrowing the drilling window and leading to well instability, kicks, mud losses, casing damages etc. This study proposes a critical analysis and the application of two methods for estimating pore pressure, that of Eaton (1975) and Bowers (1995), pointing the main assumptions, advantages and limitations, taking into account a systematic work considered compatible with the state of art used by international oil companies. The first one is based on the occurrence of only undercompaction, its use is established in the oil industry and its equations are the most used in commercial simulators. On the other hand, Bowers Method proposes a graphical analysis to account for other overpressure mechanisms besides undercompaction. In this study, the two methods were evaluated by pore pressure estimative using seismic velocity data and wells electric profiles from two deepwater oil fields in the Sergipe ¿ Alagoas Basin (Brazil) within the Upper Cretaceous Calumbi Formation. The results of both methods were analyzed and compared with pressure data measurements in reservoirs of Campanian and Maastrichtian ages, shown in general, very good or good correlation within the quality parameters set. Eaton¿s Method was used previously to understand the fields¿ pressure behavior of the two fields. It was demonstrated that, despite Eaton¿s apparent limitation, it is simpler, easier to apply and calibrate and less dependent on specific porosity logging measurements than Bowers¿ Method. The latter one was considered unstable, with its application dependent on parameters that do not make it as widely or simple to use and interpret as Eaton¿s method, even in oil fields in their development phases / Mestrado / Explotação / Mestra em Ciências e Engenharia de Petróleo

Soot is a carbon particulate formed as a result of the combustion of fossil fuels. Due to the health hazard posed by the carbon particulate, government agencies have applied strict regulations to control soot emissions from road vehicles, airplanes, and industrial plants. Thus, understanding soot formation and evolution is critical. Practical combustion devices operate at high pressure and in the turbulent regime. Elevated pressures and turbulence on soot formation significantly and fundamental understanding of these complex interactions is still poor. In this study, the effects of pressure and turbulence on soot formation and growth are investigated numerically. As the first step, the evolution of the particle size distribution function (PSDF) and soot particles morphology are investigated in turbulent non-premixed flames. A Direct Simulation Monte Carlo (DSMC) code is developed and used. The stochastic reactor describes the evolution of soot in fluid parcels following Lagrangian trajectories in a turbulent flow field. The trajectories are sampled from a Direct Numerical Simulation (DNS) of an n-heptane turbulent non-premixed flame. Although individual trajectories display strong bimodality as in laminar flames, the ensemble-average PSDF possesses only one mode and a broad tail, which implies significant polydispersity induced by turbulence. Secondly, the effect of the flow and mixing fields on soot formation at atmospheric and elevated pressures is investigated in coflow laminar diffusion flames. The experimental observation and the numerical prediction of the spatial distribution are in good agreement. Based on the common scaling methodology of the flames (keeping the Reynolds number constant), the scalar dissipation rate decreases as pressure increases, promoting the formation of PAH species and soot. The decrease of the scalar dissipation rate significantly contributes to soot formation occurring closer to the nozzle and outward on the flames wings as pressure increases. The scaling of the scalar dissipation rate is not straightforward due to buoyancy effects. Finally, a new scaling approach of the flame at different pressures is introduced. In this approach, both Reynolds number and Grashof number are kept constant so that the effect of gravity is the same at all pressures. In order to keep Gr constant, this requires the diameter of the nozzle to be changed as pressures vary. This approach guarantees a similar non-dimensional flow field at all pressures and rules out the effect of hydrodynamics and mixing, so that only the effect of chemical kinetics on soot formation can be studied.

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The topic of this master´s thesis is a design of high-pressure washer designed for hobby and semi-professional users. The work deals with analysis of current state of knowledge, basic technical parameters and the design of high pressure washer. The goal of this thesis is to create a new product that will meet technical, ergonomic and aesthetic requirements.

Felsic granulites from the Kutná Hora complex in the Moldanubian zone of central Europe preserve mineral assemblage that record transition from early eclogite to granulite facies conditions, and exhibit discordant leucocratic veining, which is interpreted as evidence for melt loss during the decompression path. The granulites are layered and consist of variables proportions of quartz, ternary feldspar, garnet, biotite, kyanite, and rutile. In the mesocratic layers, garnet grains show relatively high Ca contents corresponding to 28-41 mol. % grossular end member. They have remarkably flat compositional profiles in their cores but their rims exhibit an increase in pyrope and a decrease in grossular and almandine components. In contrast, garnets from the leucocratic layers have relatively low Ca contents (15-26 mol. % grossular) that further decrease towards the rims. In addition to modelling of pressure-temperature pseudosections, compositions of garnet core composition, garnet rim- ternary feldspar-kyanite-quartz equilibrium, ternary feldspar composition, and the garnet- biotite equilibrium provide five constraints that were used to constrain the pressure- temperature path from eclogite through the granulite and amphibolite facies. In both layers, garnet cores grew during omphacite and phengite dehydration...

In this work, optical pump – near-infrared probe and near-infrared pump – mid-infrared probe spectroscopy are used for the investigation of pressure-induced insulator-tometal transitions in transition metal oxide compounds. The materials under study are a-Fe₂O₃, also known as hematite, and VO₂. Both materials undergo pressureinduced metallization. However, the physical mechanisms of this phase transition are very different for these systems and have not been fully understood up to now. Using ultrafast pump-probe spectroscopy we obtain an insight into the evolution of the band structure and electron dynamics across the insulator-to-metal transition. In the case of VO₂, our near-infrared pump – mid-infrared probe experiments reveal a non-vanishing pumping threshold for photo-induced metallization even at our highest pressures around 20 GPa. This demonstrates the existence of localized charge carriers and the corresponding persistence of a band gap. Besides the threshold behaviour for photo-induced metallization, the carrier relaxation time scale, and the linear reflectivity and transmissivity have been studied under pressure increase. An anomaly in the threshold behaviour as well as the linear reflectivity and transmissivity at a critical pressure around 7 GPa indicates band gap filling under pressure. This is further supported by results obtained under decompression, where the changes of the linear reflectivity turned out to be almost fully reversible. The observations on VO₂ are highly reproducible and can be explained in terms of a pressure-induced bandwidth-driven insulator-to-metal transition. Fe₂O₃ has been studied via optical pump – near-infrared probe spectroscopy up to pressures of 60 GPa. In the pressure range up to 40 GPa, the changes of the response can be explained by photo-induced absorption and bleaching. The pressure-dependent study of the relaxation dynamics allows to identify cooling of the electron system as origin of the picosecond relaxation process.