The partition of radionuclides between solid and solution phase has been studied in humic/quartz sand ternary systems. Data have been recorded under ambient (air) and inert (O2 and CO2 free) atmospheres. For Eu (III) and Th (IV), the systems show simple ternary behaviour, with sorption decreasing (and mobility increasing) in the presence of humic, whilst for U (VI), the behaviour is more complex, with the humic enhancing sorption and reducing mobility. There is also evidence that the sorbed humic has an enhanced affinity for the uranyl, which is probably due to fractionation of the humic. Further, the behaviour of plutonium has also been studied in these systems. Pu (IV) showed the simple ternary characteristics, which had been observed for Eu (III) and Th (IV). Pu (V) and Pu (VI) systems exhibited more complex behaviour, with low concentrations of humic actually enhancing sorption, probably due to ternary complex formation. A simple mathematical model has been developed to predict the behaviour of both metal ion and humic acid. The model performs well in predicting the partition of the humic and that of the metal ions in the systems that show simpler ternary behaviour.

Consideramos um modelo de interações quadrupolares entre micelas capaz de explicar a ocorrência de fases nemáticas biaxiais. Micelas uniaxiais de formatos variáveis, representando a polidispersividade do sistema, são incluídas. O modelo apresenta uma fase nemática calamítica separada de uma fase discótica por uma fase biaxial, segundo resultados de campo médio e de simulações de Monte Carlo. / We consider a model of quadrupole interactions between micelles which is able to explain the occurrence of biaxial phases. Uniaxial micelles of variable shape, representing system polydispersity, are included. The model displays a calamitic nematic phase separated from a discotic phase by a biaxial phase, according to mean-field and Monte Carlo simulation results.

Consideramos um modelo de interações quadrupolares entre micelas capaz de explicar a ocorrência de fases nemáticas biaxiais. Micelas uniaxiais de formatos variáveis, representando a polidispersividade do sistema, são incluídas. O modelo apresenta uma fase nemática calamítica separada de uma fase discótica por uma fase biaxial, segundo resultados de campo médio e de simulações de Monte Carlo. / We consider a model of quadrupole interactions between micelles which is able to explain the occurrence of biaxial phases. Uniaxial micelles of variable shape, representing system polydispersity, are included. The model displays a calamitic nematic phase separated from a discotic phase by a biaxial phase, according to mean-field and Monte Carlo simulation results.

<p> This dissertation is concerned with establishing the conditions under which planar phase interfaces are morphologically unstable during phase transformations in isothermal ternary systems. First, linear perturbation methods are employed in a detailed treatment of precipitatematrix interface stability for dilute ternary systems. Following this, the stability of the planar interface in a two-phase ternary diffusion couple is examined with the aid of perturbation theory. An experimental investigation into the stability of <alpha>-<beta> phase interfaces in the Cu-Zn-Ni system at 775°C is described. The results of this experimental study are shown to be in good agreement with the earlier theoretical predictions. </p> / Thesis / Doctor of Philosophy (PhD)

Orientador: João Carlos de Andrade / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-08T12:04:09Z (GMT). No. of bitstreams: 1 May_GydaMarie_D.pdf: 1117218 bytes, checksum: da4af99338bc640a6cd71e1718ad9c8d (MD5) Previous issue date: 2006 / Doutorado / Quimica Analitica / Doutor em Ciências

Orientadores: Roger Josef Zemp, Ana Maria Frattini Fileti / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-04T03:59:01Z (GMT). No. of bitstreams: 1 Ribeiro_ValeriaSantana_M.pdf: 3503404 bytes, checksum: 3030e0b52819fa164dbcd760c731404b (MD5) Previous issue date: 2005 / Resumo: Na literatura são apresentados vários modelos termodinâmicos para o ajuste de dados de equilíbrio líquido-vapor (ELV) multicomponentes. Entretanto, devido à complexidade destes modelos termodinâmicos para interpolar dados para pressões onde dados experimentais não são disponíveis, foi proposto o uso das Redes Neurais Artificiais. Inicialmente a resolução de equações de equilíbrio líquido-vapor foi feita através de cálculos do ponto de Bolha T para o sistema ternário 2-buranol 2-butanona- água a fin de se obter uma grande quantidade de dados para serem usados nos treinamentos das redes. O modelo termodinâmico usado na representação da fase líquida foi NRTL (Non-Random-Two-Liquid). Estes dados foram então usados para treinar e testar os modelos de redes neurais, e nós verificamos que as redes neurais foram capazes de descrever o comportamento de equilíbrio com pequenos desvios nas composições preditas para o vapor em sistemas isobáricos. Um modelo neural foi então desenvolvido no MATLAB para fazer predição das propriedades termodinâmicas para o sistema 2-butanol-2-btanona-água, usando dados em diferentes pressões para treinas a rede, e predizer a composição de vapor e temperaturas em pressões na usadas no treinamento das redes. Como esperado, resultados muito pobres foram obtidos quando dois conjuntos de dados isobáricos usados para predizer o comportamento de ELV em uma pressão intermediária... Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: Many thermodynamic models for the data correlation of multicomponent liquid-vapor equilibrium (LVE) can be found in the literature. However, due the difficulty of these thermodynamic models to interpolate data at pressures where experimental data is not available, the use of Artificial Neural Networks was considered. Initially the resolution of liquid-vapour equilibrium equations was made through calculations of the bubble-point T for the ternary system 2-butanol / 2-butanone / water in order to get a reasonable amount of data to be used in the training of the networks. The thermodynamic model used in the representation of the liquid phase was NRTL (Non-Random-Two-Liquid). These data were then used to train and test neural network models, and we verified that the neural nerworks were capable of describing the equilibrium behavior with small deviations in predicted vapor composition, for isobaric systems. A neural model was then developed in MATLAB to make predictions of thermodynamic properties for the 2-butanol / 2-butanone / water system, using data at different pressures to train the network, and predict vapor composition and temperature at pressures nor used to train the network. As expected, a very poor result was obtained when two isobaric sets of data were used to predict LVE behavior at an intermediate pressure... Note: The complete abstract is available with the full electronic digital thesis or dissertations / Mestrado / Sistemas de Processos Quimicos e Informatica / Mestre em Engenharia Química

Ternary systems comprising DNA/RNA, proteins and one (or more) metal ion are generating increased interest due to its biological relevance. The knowledge gained from the study of these systems could provide important clues regarding the precise mechanism for transcription factors, repair proteins and metal complexes with anti-tumoral/anti-viral activities.The interactions occurring among the components of these ternary systems can be broadly grouped into covalent and non-covalent. The first kind of interactions can lead to the irreversible transformation of the components in the system, while the second is thought to be reversible leading to transient states and fluxionality. Both kinds of interaction are generally present in living systems, complementing the function of each other.Monofunetional Platinum-nucleobase complexes (MPNs) are synthesized via substitution of a chloride ligand by a nucleobase in platinum complexes with trans geometry. MPNs are particularly interesting for the study of ternary systems since they mimic the first step in the formation of a platinum-DNA adduct and their interaction with aminoacids/proteins provide a good first approach for more complex systems.The presence of the nucleobase as a ligand, significantly modifies the biological activity of these complexes by reducing its cytotoxicity and generating a promising anti-viral activity, especially against HIV-1 virus. The specific role of the nucleobase ligand on these complexes as a non-covalent motif, important for protein recognition, was explored in models involving tryptophan/N-acetyl tryptophan and a small protein domain called zinc finger, containing also a tryptophan residue.The coordination of the nucleobase to a metal ion such as Pt(II) or Pd(II) was found to increase its π-stacking interaction towards aromatic residues in proteins, specifically tryptophan. The enhancing effect was found to depend on the nature of the metal ion, nature of nucleobase and size/complexity of the protein model. Furthermore, DFT studies revealed an important change in the energy for the lowest unoccupied molecular orbital (LUMO) in the coordinated nucleobases, which could place this orbital in an favored position to interact with the highest occupied molecular orbital (HOMO) in the tryptophan residue. Results from calculations showed a good correlation with experimental evidence and could indicate an important role for the frontier molecular orbitals (HOMO/LUMO) of the species involved in the π-stacking interaction.This study was extended to a zinc finger domain from an essential protein in HIV-1 virus, i.e. nucleocapsid protein NCp7. Findings showed that the nucleobase ligand in addition to modulate hydrolysis and reaction rates for MPNs can also be responsible for an initial non-covalent recognition towards a specific protein. This initial recognition has been proposed as the first stage in a two-step mechanism of action for these platinum complexes that ultimately can lead to zinc ejection from the zinc finger domain in the viral NCp7. The significance of the data presented show that is possible to modulate the ligand coordination sphere in metal complexes to can result in great differences in terms of biological effects.The novel chemistry derived from DNA adducts with platinum complexes with a trans geometry was also explored in silico. The molecular dynamics of two free DNA 20-mer is compared with the corresponding metallated-adducts, namely monofunctional, 1,2-bifunctional interstrand and 1,3-bifunctional intrastrand. The differences in terms of structure and energy are compared for these systems, in general the monofunctional adduct exhibited the most interesting feature in terms of structural change in the DNA double strand causing the destacking of the metallated nucleobase. Bifunctional adducts exhibited loss of Watson-crick bonds and localized change in sugar puckering. These results showed that important differences can be found for platinated DNA even at short simulation times < 1 ns.

The sorption of humic acid (HA) and HA size fractions onto magnetite has been studied. There is considerable irreversibility in the interaction of the humic with the magnetite surface, but the presence of Eu3+ ions has no effect on the sorption of humic onto magnetite. The magnitude of the sorption to magnetite increases with HA fraction size for all ionic strengths between 0.01 and 3 mol dm-3. Increasing ionic strength also increases sorption. Asymmetric Flow Field Flow Fractionation analysis of HA sorption to magnetite after 1 day revealed preferential sorption of lower molecular weight material. Eu3+ sorption onto magnetite was studied as a function of Eu concentration, which showed an increase in relative sorption as Eu concentration decreased. The behaviour of Eu3+ in ternary (HA/Eu3+/magnetite) systems is heavily influenced by HA, and from the data there is direct evidence for ternary complex formation. Larger HA size fractions retain more Eu3+ in solution than the smaller fractions. The binding strengths of HA size fractions were determined through ion exchange resin experiments: generally the larger fractions (> 10 kDa) showed stronger binding than the smaller components, but the unfractionated sample showed the strongest binding.First order dissociation rate constants have been determined for the whole HA and HA size fractions. The dissociation rate constants are independent of HA fraction size, but the larger species bind more Eu non-exchangeably. Time series ultrafiltration of Eu3+/whole humic mixtures has shown a shift in the distribution of metal ions to larger size fractions after a few days. Two ternary system kinetic speciation models have been developed to predict the behaviour of HA and Eu3+ in ternary systems. The two differ in their description of the multi-component behaviour of the binary HA-mineral interaction. The first assumes a single HA species and two surface binding sites and was found to perform better overall than the second, which has a single surface sorption site and two HA species in solution. The exchangeable binding strengths for the different HA samples calculated from both models showed similarities to those measured experimentally.

Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-08-16T13:03:53Z No. of bitstreams: 1 JULIANA CORDEIRO NUNES - TESE (PPGEQ) 2017.pdf: 2293745 bytes, checksum: c60baeed38c440f535a6b8170f9736f4 (MD5) / Made available in DSpace on 2018-08-16T13:03:53Z (GMT). No. of bitstreams: 1 JULIANA CORDEIRO NUNES - TESE (PPGEQ) 2017.pdf: 2293745 bytes, checksum: c60baeed38c440f535a6b8170f9736f4 (MD5) Previous issue date: 2017-09-15 / A pesquisa por fontes alternativas de energia tem sido cada vez mais intensa. Nesse contexto, surge o biodiesel, biocombustível que apresenta as seguintes características: emite menos poluente que o diesel de petróleo, biodegradável, renovável, não tóxico, dentre outras. O biodiesel é produzido através da reação de transesterificação, onde o óleo vegetal ou a gordura animal reage com álcool de cadeia curta na presença de um catalisador. O óleo de girassol é uma oleaginosa com potencial utilização para a produção do biodiesel, visto que pode ser plantada no Nordeste brasileiro no período chuvoso. Após a reação de transesterificação, o produto reacional contém impurezas que precisam ser retiradas e, para isso, devem ser realizadas a lavagem e a purificação do produto reacional. Para realizar a lavagem e a purificação é necessário conhecer o equilíbrio líquido-líquido de misturas formadas por água, glicerina, biodiesel e álcool. E, para isso, pode ser preciso ter posse dos dados termodinâmicos. O objetivo deste trabalho é realizar o estudo termodinâmico sobre o equilíbrio de fases de sistemas ternários (biodiesel de girassol – álcool – glicerina) e pseudoquaternários (biodiesel de girassol – álcool – glicerina – água/ácido diluído). Para isso, foi utilizado o método da minimização da energia de Gibbs, à temperatura e pressão constantes. Para representar as fases formadas em cada sistema, foi empregado o modelo UNIQUAC. Os parâmetros de interação binária entre os compostos foram estimados através do método dos mínimos quadrados. O sistema ternário formado por biodiesel metílico de girassol – metanol – glicerina, foi analisado à 25ºC, 35ºC e 45ºC e foi observado que o efeito da temperatura foi pouco expressivo, havendo uma pequena redução da região de imiscibilidade à 45ºC. Foram estudados os sistemas pseudo-quaternários formados por biodiesel metílico de girassol – metanol – glicerina – água destilada/ácido sulfúrico diluído, o sistema ternário de biodiesel etílico de girassol – etanol – glicerina e também os sistemas pseudo-quaternários formados por biodiesel etílico de girassol – etanol – glicerina – água destilada/ácido sulfúrico diluído. Em todos os sistemas pseudo- quaternários foi observado que a presença de água/ácido diluído: aumenta a região de separação de fases, não havendo alteração expressiva no comportamento da curva ao aumentar a quantidade de água destilada/ácido diluído de 50% para 75% em relação à massa da glicerina; e diminui a solubilidade do biodiesel na fase rica em glicerina+água destilada/ácido diluído. Na modelagem termodinâmica do ELL, os dados experimentais foram comparados com os valores calculados pelo modelo UNIQUAC, onde obteve-se uma boa concordância entre os dados experimentais e os valores calculados, uma vez que o maior desvio apresentado foi de 0,27%. Isso mostra que, no estudo no ELL dos sistemas analisados, podem ser utilizados os parâmetros calculados. Observou-se que é satisfatório o uso do modelo UNIQUAC para tais sistemas. / The search for alternative sources of energy has been increasingly intense. In this context, it appears the biodiesel, biofuel that has the following characteristics: it emits less pollutant than petroleum diesel, biodegradable, renewable, non-toxic, among others. biodiesel is produced through the transesterification reaction, where vegetable oil or animal fat reacts with short chain alcohol in the presence of a catalyst. Sunflower oil is an oleaginous with potential use for the production of biodiesel, since it can be planted in the Brazilian Northeast during the rainy season. After the transesterification reaction, the reaction product contains impurities that need to be removed and, for this, the wash and purification of the reaction product must be carried out. To carry out the washing and the purification it is necessary to know the liquid-liquid equilibrium of mixtures formed by water, glycerine, biodiesel and alcohol. And for that, it may be necessary to have possession of the thermodynamic data. The objective of this work is to perform the thermodynamic study on the phase equilibrium of ternary systems (sunflower biodiesel - alcohol - glycerin) and pseudo - quaternaries (sunflower biodiesel - glycerine - water / diluted acid). The Gibbs energy minimization method was used at constants temperature and pressure. To represent the phases formed in each system, the UNIQUAC model was used. The parameters of binary interaction between the compounds were estimated using the least squares method. The ternary system formed by sunflower methyl biodiesel - methanol - glycerin was analyzed at 25ºC, 35ºC and 45ºC and it was observed that the effect of the temperature was not very expressive, with a small reduction of the region of immiscibility at 45ºC. We studied the pseudo quaternary systems formed by sunflower methyl biodiesel - methanol - glycerol - distilled water / diluted sulfuric acid, the ternary l system of ethyl biodiesel of sunflower - ethanol – glycerin and also the pseudo - quaternary systems formed by sunflower ethyl biodiesel - ethanol - glycerin - distilled water / diluted sulfuric acid. In all pseudo-quaternary systems it was observed that the presence of diluted water / diluted acid: increases the region of phase separation, with no significant change in the behavior of the curve by increasing the amount of distilled water / diluted acid from 50% to 75% relative to the glycerol mass; and decreases the solubility of biodiesel in the rich phase at glycerin + distilled water / dilute acid. In the thermodynamic modeling of the LLE, the experimental data were compared with the values calculated by the UNIQUAC model, where a good agreement was obtained between the experimental data and the calculated values, since the largest deviation was 0.27%. This shows that, in the LLE study of the analyzed systems, the calculated parameters can be used. It was observed that the use of the UNIQUAC model for such systems is satisfactory.

The theory of the lamellar eutectoid reaction by volume diffusion has been extended to account for solute segregation within the product phases and the effect of dilute third element additions. It has been demonstrated for symmetric binary systems that the segregation can account for 10% or more of the free energy stored in the product phases and can lead correspondingly to a predicted lamellar spacings appreciably greater than those obtained when segregation is neglected. This segregation is relatively high in the systems Cu-In, Cu-Be and Ag-Cd and may account for the fact that a secondary coarse-grained pearlitic reaction follows the initial fine grained one in these systems. The binary theory has been-used to analyse the available data for the eutectoid reaction in the Cu-Al and Fe-C systems and satisfactory agreement is obtained. The theory for ternary systems, while complete in principle, proves to be. intractable in all but the simplest version of the solution thermodynamics. It is concluded that the effect of the third element on the binary eutectoid reaction is mainly through its effect on the phase diagram, the ternary cross effects in the diffusion matrix tending to cancel out. Any additional element which lowers the eutectoid temperature will retard the reaction. / Thesis / Doctor of Philosophy (PhD)