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Item Variação da energia livre na hidratação de séries homólogas de poliol, glicina e peptídeos ANK usando modelos contínuo e discreto de solvente(Universidade Federal de Goiás, 2017-05-12) Abreu, Leonardo Martins de; Fileti, Eudes Eterno; http://lattes.cnpq.br/5294929829300325; Fonseca, Tertius Lima da; http://lattes.cnpq.br/8193800922148980; Fonseca, Tertius Lima da; Moreno, Roberto Rivelino de Melo; Fujimoto , Milton Massumi; Vale, Renato Pessoa; Silva, Ladir Cândido daUsing continuum and discrete solvent description models, we have investigated the chain length dependence of hydration free energy of polyol, glycine and ANK peptides. In this work this property values were calculated using thermodynamics integration with classical molecular dynamics simulation of one solute molecule to around 1000 solvent molecules. In addition, hydration free energy of polyol, glycine and ANK peptides were also calculated using polarizable continuum model in combination with the universal solvation model. Dipole moment and linear polarizability of the three systems had been also calculate using the PCM method. Our MD results show that ΔG exhibit a linear pattern with the size of glycine and ANK chain as well as observed for organic compounds in literature. In opposition, polyol’s ΔG shows a nonlinear behavior with increasing chain length and for this group of molecules it were found that water solvating effects have an important role over the polyol’s electric properties. These results suggest that in the case of polyols not only variation of polarizability but also variations of dipole moment in going from vacuum to water can influence the behavior of the free energy of hydration. All DM and PCM calculations were performed using the GROMACS 4.5 and the GAUSSIAN09 programs, respectively.Item Instabilidade modulacional em equações não lineares de Schrödinger(Universidade Federal de Goiás, 2015-10-16) Alves , Erivelton de Oliveira; Cardoso , Wesley Bueno; http://lattes.cnpq.br/6845416823133684; Avelar , Ardiley Torres; http://lattes.cnpq.br/5732286631137637; Avelar , Ardiley Torres; Cardoso , Wesley Bueno; Souza , Márcio Adriano Rodrigues; Bazeia Filho , Dionízio; Malbouisson , Jorge Mario CarvalhoIn this work the influence of a saturable nonlinearity on the modulation instability (MI) in the contexts oppositely directed coupler and optical fibers in the presence of high-order effects are investigated. The instability gain is attained by using standard linear stability analysis. In particular, we study the combination of a saturable nonlinearity with self-steepening or intrapulse Raman scattering effects on MI for both normal and anomalous group velocity dispersion regimes. In the case of the directional couplers we investigated how the gain of modulational instability is affected by the saturation model and self-steepening or intrapulse Raman scattering effects. Our results show that instability gain exhibits significant changes due to the effects of saturable nonlinearity. When we analyze self-steepening effect, we show that its effective influence on the gain of the modulational instability depends on the algebraic sum of the parameters in each channel. Analyzing the intrapulse Raman scattering, we observe a symmetry break in the gain regions when the Raman scattering parameter with opposite signals in each channel is considered. Finally, in the context of optical fibers we show how the reduction of the Of the gain frequency of the IM, induced by saturation, can drastically limit the formation of soliton trains.Item Estudo teórico sobre membranas peptídicas e lipídicas: uma análise via dinâmica molecular(Universidade Federal de Goiás, 2021-08-10) Alves, Eyber Domingos; Oliveira, Guilherme Colherinhas de; http://lattes.cnpq.br/0171051425848743; Oliveira, Guilherme Colherinhas de; Castro, Marcos Antonio de; Almeida, Norton Gomes de; Ludwig, Valdemir Eneias; Fileti, Eudes EternoIn this work, the molecular dynamics formalism was used to study the physicochemical properties of peptide and lipid membranes when immersed in solution. Concerningpeptide membranes, the energetic and structural properties were evaluated in the situations in which these membranes were immersed in the Ionic Liquid (IL) formed by the choline (COL) and glycine (GLY) pair. The results indicate the existence of energetic and structural stability of these membranes when in IL, with potential application in energy storage in biodegradable supercapacitors. For lipid membranes, we used the umbrella sampling technique to proceed with a series of 150 insertions of the Fullerene-C 60 molecule in four lipid membranes composed of DOPC (Dipalmitoylphosphatidylcholine) at a ratio of 00% (pure membrane), 10%, 20% and 30% of cholesterol molecules, evaluating the average behavior of molecular insertion energies. The results showed that the presence of cholesterol molecules makes the inclusion process of Fullerene-C 60 energetically unfavorable. Under the computational pathway, we evaluated the pharmacological characteristics associated with monomers constructed based on peptides. For this purpose, we interact the lipid membranes composed of DOPC (Dipalmitoylphosphatidylcholine) at a proportion of 00% (pure membrane), 10% and 30% of cholesterol molecules with the peptide drug L-GL13K. The results reveal that the hydrogen bonds between the compound L-GL13K and the DOPC molecules promote membrane destabilization and increasing the infiltration of water molecules.Item Estudo de soluções localizadas na equação não linear de Schrödinger logarítmica, saturada e com efeitos de altas ordens(Universidade Federal de Goiás, 2018-06-07) Alves, Luciano Calaça; Avelar, Ardiley Torres; http://lattes.cnpq.br/5732286631137637; Cardoso, Wesley Bueno; http://lattes.cnpq.br/6845416823133684; Bazeia Filho, Dionisio; Valverde, Clodoaldo; Santana, Ricardo Costa de; Maia, Lauro June QueirozThis work presents the study of solitary wave solutions, known as solitons, in non-linear and non- homogeneous media using non-linear Schrödinger equations. Three cases are studied: first considering a logarithmic nonlinear term; second with saturation effect and finally including effects of high orders (Raman scattering). Solutions are modulated by three different types of potential. First, linear in the spatial and oscillatory coordinate in the temporal coordinate. The second, quadratic in the spatial and oscillatory in the temporal coordinates. Finally, it is also modulated using a mixed potential, which is the junction of the two potentials presented above. After including inomogeneities in linear and nonlinear coefficients, the similarity transformation technique is used to convert the non-linear, non-autonomous equation into an autonomous one that will be solved analytically. This field of study has potential applications in crystals, optical fibers and in Bose- Einstein condensates, also serving to understand the fundamentals related to this state of matter. The stability of the solutions are checked by numerical simulations.Item Versatilidade estrutural de aminoácidos agregados: design de nanomateriais orgânicos via dinâmica molecular(Universidade Federal de Goiás, 2022-02-25) Andrade, Douglas Xavier de; Oliveira, Guilherme Colherinhas de; http://lattes.cnpq.br/0171051425848743; Oliveira, Guilherme Colherinhas de; Cruzeiro, Vinícius Wilian dias; Fonseca, Tertius Lima da; Ludwig, Valdemir Eneias; Georg, Herbert de CastroIn this work, we carried out structural and energetic characterization of nine nanomembranes and two nanofibers composed of surfactant-like peptides (SLPs), using Molecular Dynamics (MD) simulations with atomistic resolution. The nanomembranes [nanofibers] studied are formed by the peptides I3V3A3G3K3 and K3G3A3V3I3 [G3A3V3I3K3 and K3I3V3A3G3]; A6Hε and A6Hδ; and I3XGK (X = Q, S, N, G or L). The nanomembranes I3V3A3G3K3 and K3G3A3V3I3 are formed by the same amino acids, but linked in inverted primary sequences, which changes torsions, the side chains, and the C and N peptide terminals, affecting the hydration and stability of the nanomembranes. The A6Hε and A6Hδ nanomembranes are differentiated by the position of the hydrogen atom attached to the aromatic ring of histidine (H) residues, alterning the way that this residue is exposed to water, and consequently, the lateral attachment of alanine residues (A). By studying the I3XGK (X = Q, S, N, G or L) nanomembranes, we realized that the peptides with polar residues (X = Q, S, or N) present properties of polar zippers connecting β-sheets laterally. Therefore, this work aims at elucidating and characterizing the formation of polar zippers that, recently, have attracted significant scientific and technological interest. The nanofibers G3A3V3I3K3 and K3I3V3A3G3 are formed by peptides with the same amino acids, but linked in inverted primary sequences, similar to the case of the nanomembranes I3V3A3G3K3 and K3G3A3V3. This way, by studying nanomembranes and nanofibers composed with the same amino acids, this work allows us to understand how changes in the disposition of the peptide side chains lead to the formation of distinct nanostructures, evidencing the structural versatility of aggregate amino acids. The analyses performed are based on the mass density profiles, on nanomembrane thicknesses, on the radial distribution functions, g(r), on the average number of Hydrogen Bonds (HBs) between amino acids and between each amino acid and water molecules - for a better characterization of HBs between peptides and consequently the nanomembranes’ hydration, HB’s time correlation functions are presented - and in the Coulombic and vdW energetic interactions which together with the HBs play a fundamental role in the organization of the peptides forming the nanostructures. Our results indicate that the C-terminal attached to the charged lysine (K) leads to the formation of more hydrated nanomembranes; the A6Hε and A6Hδ are nanostructures with a high degree of organization and with features of crystalline structures; the polar zippers present an interesting route for the design of robust and stable nanostructures, by joining neighboring β-sheets; the peptide nanostructures presented in this work have interesting characteristics suggesting that they can be used to encapsulate and transport drugs, as hydrogels and as an antimicrobial agent. Our MD results show excellent agreement with experimental data reported in the literature. In addition, we show that the CHARMM36 force field could be recommended for the study of the peptide nanomembranes and nanofibers presented. This validation is important because it allows the prediction from the theoretical point of view of new features of peptide structures of this species, providing advances in the development of organic nanostructures.Item Interações da albumina de soro bovino com surfactantes e efeitos de antioxidantes sobre a oxidação de lipoproteínas de baixa densidade induzida por íons de cobre(Universidade Federal de Goiás, 2012-08-02) ANJOS, Jorge Luiz Vieira dos; ALONSO, Antônio; http://lattes.cnpq.br/5013069863616789Human plasma contains primarily large proteins, ranging in composition and concentration as the individual's physiological state. Among these proteins, albumin and low density lipoprotein (LDL) have been widely studied. The albumin (the most abundant protein in blood plasma) is responsible for important functions in the human body due to its excellent ability to bind and transport small molecules. In turn, the LDL (responsible for transporting cholesterol to the cells) in its oxidized form is directly associated with atherosclerosis, the main cause of cardiovascular disease. In the first part of this work, the interaction of bovine serum albumin (BSA) with the ionic surfactants sodium dodecylsulfate (SDS), cetyltrimethylammonium chloride (CTAC) and N-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (HPS) was studied by electron paramagnetic resonance (EPR) spectroscopy of spin label covalently bound to the single free thiol group of the protein. In the second part was studied the oxidation of human LDL by copper ions and also the antioxidant potential of polyphenols resveratrol, (+)-catechin and quercetin, using the EPR of a spin label, derived from stearic acid (5-DSA), and the method malondialdehyde content (MDA). Part I: The dynamics of the BSA and the thermodynamic parameters for transferring the nitroxide side chain from the more motionally restricted to the less restricted component were monitored through EPR spectra simulation. Whereas SDS and CTAC showed similar increases in the dynamics of the protein backbone for all concentrations used, HPS presented a smaller effect at concentrations above 1.5mM. At 10mM of surfactants and 0.15 mM BSA, the standard Gibbs free energy change was consistent with protein backbone conformations more expanded and exposed to the solvent, but with a less pronounced effect for HPS. In the presence of the surfactants, the enthalpy change, related to the energy required to dissociate the nitroxide side chain from the protein, was greater, suggesting a lower water activity. The nitroxide side chain also detected a higher viscosity environment in the vicinity of the Mal-5 induced by the addition of the surfactants. The results suggest that the surfactant-BSA interaction, at higher surfactant concentration, is affected by the affinities of the surfactant to its own micelles and micelle-like aggregates. Complementary DLS (Dynamic Light Scattering) data suggests that the temperature induced changes monitored by the Mal-5 reflects local changes in the vicinity of Cys-34 BSA residue. Part II: The oxidative process induced by copper ions results in lipid peroxidation of LDL (evidenced by high concentration of MDA) could also be monitored by the decrease in the dynamics of 5-DSA, reflected in increased spectral parameter 2A//. The oxidation of LDL resulted in increased energy barrier that the spin labels must overcome to achieve higher degrees of motion. All polyphenols studied were able to protect LDL completely against oxidation for concentrations from 30 M, whereas the protection provided by the Butylated hydroxytoluene (BHT) occurred only partially. This result, based on data from the literature, was attributed to the ability of polyphenols act as scavenger and chelating agents, while the BHT acts just like scavenger due the presence of only a single hydroxyl group in its molecule.Item Eficiência de um motor térmico de Otto quântico baseado em um sistema de dois níveis(Universidade Federal de Goiás, 2021-12-09) Assis, Rogério Jorge de; Almeida, Norton Gomes de; http://lattes.cnpq.br/3182841849332242; Almeida, Norton Gomes de; Serra, Roberto Menezes; Cardoso, Wesley Bueno; Brito, Frederico Borges de; Pinto, Diogo de Oliveira SoaresClassical thermodynamics, also called equilibrium thermodynamics, is a theory that deals with macroscopic systems in equilibrium. After its development, other theories emerged to encompass macroscopic out-of-equilibrium systems. Over the past few decades, researchers have developed a new theory to describe also the thermodynamics of microscopic quantum systems, which became known as quantum thermodynamics. An important application of this theory is in the development of heat engines in which the working substance (the substance responsible for transforming heat into work) is a microscopic quantum system. Due to their composition, these devices came to be commonly called quantum heat engines. Notably, recent studies have shown that using an out-of-equilibrium reservoir as a heat source can improve the performance of quantum heat engines, compared to the usual case where the heat source is an equilibrium reservoir (a thermal reservoir). In this context, this thesis presents two studies related to a quantum Otto heat engine whose working substance is a two-level system: in the first study, the engine has a squeezed thermal reservoir as the heat source, while in the second study, the heat source is a reservoir with a negative temperature. Both studies explore the finite-time regime of the expansion and compression stages of the heat engine. The first study shows that the engine efficiency can be greater than the Carnot efficiency in both the quasi-static and finite-time regimes. However, as in the usual case, decreasing the time of the expansion and compression stages degrades the engine efficiency. In its turn, the second study shows that the engine efficiency can surpass the Otto efficiency in the finite-time regime. Here, different from the usual case, decreasing the time of the expansion and compression stages can increase the engine's efficiency. Finally, the present thesis shows an experimental scheme in the nuclear magnetic resonance context able to provide a proof of concept for the engine in the different situations studied.Item Estudo das interações de porfirinas com sistemas de interesse biológico: potencial uso no transporte de fármacos e aplicação fotodinâmica(Universidade Federal de Goiás, 2019-08-23) Bezerra, Fábio de Castro; Gonçalves, Pablo José; http://lattes.cnpq.br/0515343409614452; Gonçalves, Pablo José; De Boni, Leonardo; Iglesias, Bernardo Almeida; Borissevitch, Iouri; Alonso, AntonioThe purpose of this work was to study the interactions of porphyrins in systems of biological interest aiming at drug transport and photodynamic applications. Interactions of anionic meso-tetrakis(p-sulphonatephenyl) porphyrin (TPPS4) and cationic meso-tetrakis (4- methyl-pyridyl) porphyrin (TMPyP) porphyrins with bovine serum albumin (BSA), antibodies, DNA and biocompatible nanoparticles of maghemite were evaluated. To obtain the binding constants and thermodynamic parameters, spectroscopic UV/Vis absorption and fluorescence techniques were used. Binding constants indicate a higher affinity of porphyrin TPPS4 for proteins compared to TMPyP. Thermodynamic parameters showed that electrostatic and hydrophobic interactions mediated the BSA interactions with the porphyrins TPPS4 and TMPyP, respectively. On the other hand, the nature of porphyrin-antibody interactions shows a behavior opposite to that observed for BSA (electrostatic for TMPyP and hydrophobic for TPPS4), indicating that the binding site of porphyrin TMPyP in the antibodies is likely to have a net negative charge. In the porphyrin TPPS4 interaction with maghemite nanoparticles, besides obtaining the binding parameters of the interaction, it was possible to estimate the number of 21 porphyrins coupled in each nanoparticle. Regarding the interaction of DNA with the porphyrins TPPS4, TMPyP and its complexes with zinc, it was observed that ZnTMPyP has higher affinity for DNA than TMPyP, whereas TPPS4 and ZnTPPS4 do not bind to DNA, which explains the results of photodegradation of DNA by these porphyrins. Keywords: PhotodynamicItem Efeito da interação dipolar magnética na eficiência de aquecimento de nanopartículas: Implicações para magnetohipertermia(Universidade Federal de Goiás, 2014-12-09) Branquinho, Luis Cesar; Bakuzis, Andris Figueiroa; http://lattes.cnpq.br/3477269475651042; Bakuzis, Andris Figueiroa; Pelegrini, Fernando; Franco Junior, Adolfo; Morais, Paulo Cesar de; Landi, Gabriel TeixeiraMagnetic nanoparticles can generate heat when submitted to alternating magnetic fields of adequate amplitude and frequency. This phenomenon is named magnetic hyperthermia and has several therapeutic applications, as for example, in the treatment of cancer. In general, the theoretical models used to describe this neglect the effect of interparticle interaction. In this thesis we investigate the effect of magnetic dipolar interaction in the magnetothermal efficiency (named specific loss power – SLP) of bicompatible magnetic nanoparticles. Firstly, we develop a chain of magnetic particles model, where we prove that the interaction leads to a contribution to the uniaxial anisotropy. This term in the free energy density allowed us to extract from the electron magnetic resonance technique (EMR) information about the mean chain size in the colloid. Further, this additional magnetic nanoparticle anisotropy term was used to develop an analytical theoretical model that takes into account the effect of the dipolar interaction between nanoparticles to SLP, considering the case where the magnetization responds linearly to the field (Linear Response Theory). Our calculations indicate that depending on the particle parameters, specially the anisotropy, the effect can be to enhance or decrease the heat generation. Moreover, we showed that increasing the chain size (number of particles in the chain) the optimal particle size for hyperthermia can decrease up to 30% in comparison with non-interacting particles. This result has several clinical implications, which allowed us to suggest some strategies for improving the therapeutic efficacy. In order to investigate experimentally the effect, two magnetic fluids, one containing spherical nanoparticles based on manganese ferrite (MnF-citrate) in the superparamagnetic regime, and another commercial one (BNF-starch) magnetite-based with a shape of a parallellepiped and blocked, were selected and deeply characterized. We found a decrease of SLP increasing the chain size for the MnF sample, while for BNF-starch no effect was found at the same experimental conditions. The decrease of SLP in the MnF sample, within the particle concentration range, was explained considering in the model not only the effect in the anisotropy but also by an increase in the damping factor parameter, a term correlated to spin-phonon interaction. Data obtained using EMR and Monte Carlo simulations corroborate our hypothesis. The absence of concentration effect for the BNF sample was attributed to the higher anisotropy value and to the probable influence of brownian relaxation. In addition, the same chain model was used to investigate the behavior of blocked nanoparticles of Stoner-Wohlfarth type. In this case, we demonstrate that the chain formation increases the magnetic hyperthermia, as found in magnetosomes. Finally, we showed that a fluctuation of the dipolar interaction field between particles in the chain, which does not destroy the symmetry of this term, shows a Vogel-Fulcher behaviour in the weak coupling regime.Item Estudos de membranas modelo e efeitos de terpenos em membranas de leishmania por ressonância paramagnética eletrônica(Universidade Federal de Goiás, 2013-11-16) Camargos, Heverton Silva de; Alonso, Antônio; http://lattes.cnpq.br/5013069863616789; Alonso, Antônio; Nakamura, Celso Vataru; Ruggiero Neto, João; Dorta, Miriam Cristina Leandro; Anjos, Jorge Luiz Vieira dosElectron paramagnetic resonance (EPR) spectroscopy of spin labels was used to study the main structural accommodations of environment-sensitive probes in the bilayers of saturated phosphatidylcholines with acyl chains lengths ranging from 16 to 22 carbon atoms. The more detailed analysis were made on the spin probe 5-doxyl methyl stearate (5-DMS) whose EPR spectra allowed to identify two distinct spectral components in thermodynamic equilibrium at temperatures below and above the main phase transition. The EPR spectroscopy distinguishes two components associating lower motion with higher polarity (denoted component 1) and higher motion with lower polarity (component 2), which may be assigned to one shallow (more rigid structure) and one deep population of spin probe, respectively. At temperatures until 22◦C only one spectral component can be noted in the spectra whereas at 30◦C the component 1 coexists with an appreciable fraction of component 2. In the liquid-crystalline phase the 5-MSL showed two spectral components for all studied lipids in the entire range of measured temperatures. An accurate analysis of EPR spectra, performed using two fitting programs (NLLS and EPRSIM), allowed us to obtain the thermodynamic profile to these major probe accommodations. Focusing the analysis on two-component EPR spectra, it was studied the influences of cholesterol and a membrane permeation enhancer on the mobility and distribution of spin label on these two main bilayer environments. Parte II Cutaneous leishmaniasis is a neglected tropical disease that infects millions of people worldwide, representing a serious public health problem. The current treatment is based on chemotherapy, using pentavalent antimonials compounds, which cause serious side effects. Electron paramagnetic resonance (EPR) spectroscopy of the spin-label analog of stearic acid (5-DSA ) was used to monitor the effect of the terpenes α-terpineol, 1,8-cineole, III (+)-limonene and nerolidol on the plasma membrane fluidity of Leishmania amazonensis promastigotes. Cytotoxic effects on the parasite were also measured to investigate the relationship between the cytotoxic potential of terpenes and their ability to alter membrane fluidity. All terpenes increased the fluidity of the cellular membrane, without significant differences at higher concentrations. However, the minimum concentration required to cause a change in the membrane was very different between the terpenes and similar to that caused 50% growth inhibition (IC50) showing a correlation between membrane alterations and cytotoxicity. The IC50 values of terpenes analyzed showed the following relationship: nerolidol < (+)-limonene < α-terpineol < 1,8-cineole, with an IC50 of 8 μM for nerolidol and 4700 μM to 1,8- cineole. The EPR spectra of the maleimide derivative spin label (6-MSL) covalently attached to the Leishmania membrane proteins indicated that the terpenes essentially do not alter the dynamics of protein backbone and only increase the mobility of the nitroxide side chain. Cell lysis was not detected at cytotoxic concentrations, as measured by the presence of spin-labeled membrane fragments. Since the terpenes are considered potent skin permeation enhancers with low irritation potential, this work suggests checking the possibility of terpenes applications in the treatment of tegumentary leishmaniasis, where terpenes could perhaps perform a dual action of be an active principle and at the same time facilitate the penetration of other molecules with antileishmanial activity.Item Markov monogamy inequalities(Universidade Federal de Goiás, 2022-03-09) Capela, Matheus; Araújo, Rafael Chaves Souto; ttp://lattes.cnpq.br/1509277905143351; Céleri, Lucas Chibebe; http://lattes.cnpq.br/6630683190018665; Celeri, Lucas Chibebe; Avelar, Ardiley Torres; Oliveira, Thiago Rodrigues de; Santos, Marcelo Paleologo Elefteriadis de Franca; Pinto, Diogo de Oliveira SoaresO estudo dos limites na comunicação com canais ruidosos é um problema central na teoria de informação. Data processing inequalities são de fundamental importância sob esta perspectiva. Entretanto, estas não são as as únicas condições existentes sob o processamento de informação. Neste trabalho, apresentamos uma nova categoria de condições chamadas Markov monogamy inequalities. Estes novos resultados são aplicados ao estudo e caracterização de processos não-Markovianos clássicos e quânticos. De grande importância, as condições Markov monogamy inequalities revelam-se serem mais eficientes que as data processing inequalities na certificação de processos não-Markovianos em determinados exemplos.Item Soluções localizadas em modelos de campos relativísticos e em condensados de Bose-Einstein(Universidade Federal de Goiás, 2010-07-09) CARDOSO, Wesley Bueno; AVELAR, Ardiley Torres; http://lattes.cnpq.br/5732286631137637This work combines some of the results obtained on the study of solitons in relativistic fields and Bose-Einstein condensates. By using a first order formalism to solve the equations of motion of relativistic fields, introduced previously by our group, we construct several classes of lump solutions described by a single real scalar field. We show how these solutions can be controlled depending on a single parameter in the field potential. In condensed matter the solutions of the lump type correspond to bright solitons, very studied in the context of nonlinear crystals, fiber optics, Bose-Einstein condensates, etc. In all these cases, such solutions are obtained via a nonlinear Schr¨odinger equation, responsible for describing the propagation of pulses in optical fibers or crystals, or the atomic density in condensates. In this sense, our main goal is to study the soliton and breather modulations via nonlinear Schrodinger equation. We concentrate on the Bose-Einstein condensate in which the modulation of atomic density can be accomplished through the Feshbach resonance. We study cases where the nonlinearity is described by terms cubic, cubic and quintic, and purely quintic in the nonlinear Schr¨odinger equation. Also, situations where two interacting condensates in which the nonlinear Schr¨odinger equations are coupled, breather modulations, and the study of the soliton behavior under influence of chaotic, random and non-periodic perturbations in the nonlinearity of the system. In many cases we consider the condensate trapped in the cigarshaped configuration, i.e., with freedom in only one spatial dimension. Numerical simulations are performed to verify the stability of the solutions.Item Incerteza quântica local em transições de fase quânticas e uma generalização para sistemas multipartidos(Universidade Federal de Goiás, 2018-05-02) Carrijo, Thiago Mureebe; Céleri, Lucas Chibebe; http://lattes.cnpq.br/6630683190018665; Avelar, Ardiley Torres; http://lattes.cnpq.br/5732286631137637; Almeida, Agnaldo Rosa de; Avelar, Ardiley Torres; Valverde, Clodoaldo; Oliveira, Guilherme Colherinhas de; Cardoso, Wesley BuenoIn this work, we have studied how local quantum uncertainty (LQU) and linear entropy behave in critical systems. Two models of spin 1/2 systems were investigated: XY and XY with triple interaction (XYT), both unidimensional. It was concluded that these measures and their derivatives locate the phase transitions of these systems and a justification was given for the difference of behavior between the LQU and the linear entropy in the region near the transition in the XY model. A measure of multipartite quantum correlations was also created according to a set of axiomatic criteria, which was tested in the family of Werner-GHZ quantum states, producing results in accordance with the expected result, according to the literature.Item Aspectos de modelos eletrônicos bidimensionais fortemente correlacionados: aplicações em cupratos supercondutores(Universidade Federal de Goiás, 2016-06-06) Carvalho, Vanuildo Silva de; SIlva, Hermann Freire Ferreira Lima e; http://lattes.cnpq.br/7198902316435183; Silva, Hermann Freire Ferreira Lima e; Oliveira, Luiz Nunes de; Miranda, Eduardo; Rabelo, Jose Nicodemos Teixeira; Braghin, Fabio LuisWe investigate here the low-energy properties of two strongly correlated electronic models in two spatial dimensions. The first one consists in a version of the Hubbard model in which are considered just the degrees of freedom of the system in the neighborhood of the so-called hot spots, which are defined as the intersection of the Fermi surface of the model with the antiferromagnetic zone. Initially, we set our theory up by linearizing the dispersion model in hot spots and consider all the interacting processes between these regions that conserve momentum within a reciprocal-lattice wave vector. In order to access the physics of the model, we then turn to the renormalization group method of quantum field theory and derive the flow equations for the couplings in the two-loop approximation. As a result, we obtain that the Fermi surface is strongly renormalized in hot spots as the renormalized couplings flow to a non-trivial fixed point in the low-energy limit. Then we suggest that this system can be viewed as an example of a non-Fermi liquid in two spatial dimensions, due to the lack of well defined quasiparticle fermionic excitations in the region close to hot spots. Moreover, we solve the Callan-Symanzik equation for the oneparticle Green function up to two-loop order, calculate the density of states in the hot spots, and derive the renormalization group equations for the order parameters of the potential instabilities which may eventually occur in the system at lower energies. We verify that the system can be characterized, in this regime, in terms of an emergent pseudospin symmetry [SU(2)]4, which leads to the appearance of entangled orders in the region close to the non-trivial fixed point of the model. We also show that the fermionic excitations in the adjacent regions to the hot spots get a gap in both charge a spin excitation spectra. Because of this, we argue that the Fermi surface of the model can be reconstructed, leading therefore to the formation of either Fermi arcs or electronic pockets. The second model analyzed in this thesis was the three-band Emery model, which describes all the interacting processes between fermionic excitations localized in both copper (Cu) and oxygen (O) orbitals in the CuO2 unit cell. By making use of a Hubbard-Stratonovich transformation, we introduce two order parameters in the system: one for the so-called ΘII-loop-current order, which violates Z2 time-reversal symmetry, and another one for the entangled phase with dx 2 -y 2 symmetry involving the singlet superconducting instability and the quadrupole density wave order, whose wave vector points in the direction of the Brillouin zone diagonal. Minimizing the free energy of the model, we derive the self-consistent mean-field equations for these order parameters. The solution of these equations for the zero temperature regime shows that the two phases compete with themselves for the same region of the phase space and, consequently, the system tends not to display coexistence between them. We argue that this effect could be the main reason for the fact that the quadrupole density wave order has never been observed in experiments performed on the cuprate superconductors. Next, we analyze the competition between the ΘII-loop-current order, which is experimentally observed, and charge order with dx 2 -y 2 symmetry and wave vectors in the direction of the main axes of the Brillouin zone. As a result, we obtain that the system only exhibits coexistence between the ΘII-loop-current phase and the bidirectional charge order. Due to the existence of a pseudospin symmetry in this model, we also confirm that the ΘII-loop-current phase coexists with the bidirectional pair density wave order. Finally, we discuss the implications of these results for the pseudogap phase of the cuprate superconductors, which appears in the underdoped regime in these systems.Item Avaliação da dependência com a pressão de propriedades estruturais de compostos orgânicos de interesse farmacêutico(Universidade Federal de Goiás, 2018-05-07) Castro, Rosane de Paula; Sabino, José Ricardo; http://lattes.cnpq.br/9101677399031185; Pinheiro, Carlos Basílio; Santos Júnior, Sauli dos; Bufaiçal, Leandro Félix de Sousa; Fonseca, Tertius Lima daThis thesis presents the structure determination using single crystal x-ray crystallography of four drug candidates under ambient conditions of temperature and pressure, as well as submitted to high pressure. The crystallographic analysis of this type of compound allows to obtain the three-dimensional structure in an unambiguous way. This information is useful for the development process of new drugs in order to achieve the planned properties, such as the study of combinations of the drug with the excipients to be used to guarantee the rate of expected release of the drug in the human body and the optimization of interaction between the drug and the target. Furthermore during the process of drug manufacturing in the pharmaceutical industry polymorphic phases may arise due to the application of pressure, which occurs during grinding and in the preparation of tablets, which may alter the bioavailability, solubility and stability of the medicament. Thus, identifying the conditions under which such modifications may occur guarantees the reliability of the final product. In this sense, the crystallization and crystallographic analysis of drug candidates developed by the Laboratório de Avaliação e Síntese de Substâncias Bioativas (LASSBio) of the Universidade Federal do Rio de Janeiro (UFRJ) was carried out. The compounds analyzed were: LASSBio-1773 and LASSBio-1774, which have hypoglycemic activity, LASSBio-1606, with anti-inflammatory properties, and LASSBio-1735, which has been shown to be active against several types of cancer. For the compounds LASSBio-1774 and LASSBio-1606 X-ray diffraction at high pressures was also performed with Diamond Anvil Cell (DAC), determining their unit cells and analyzing the effects of pressure on the crystalline arrangement. In both compounds reversible phase transitions were observed. The analysis of the structural changes for LASSBio-1774 due to pressure was performed with the aid of strain tensors.Item Propriedades eletrônicas e estruturais de clusters metálicos via métodos ab initio(Universidade Federal de Goiás, 2015-09-25) Damasceno Junior, Jose Higino; Silva, Ladir Cândido da; http://lattes.cnpq.br/7442411485710574; Silva, Ladir Cândido da; Vitiello, Silvio Antonio Sachetto; Fujimoto, Milton Massumi; Castro, Marcos Antônio de; Bufaiçal, Leandro Felix de SousaClusters systems are very different from molecules or their bulk materials, since they exhibit many specific properties. As example, the bond in metallic clusters of metallic atoms is intermediate between metallic and covalent bonding. In general, the structural and electronic properties of these systems are very difficult to measure experimentally, and therefore theoretical modeling is very important in characterizing them. In this thesis, we employed ab initio methods to study metallic clusters such as the aluminum hydride clusters as well as a few aromatic metal clusters. The optimized geometries of the studied clusters have been determined using DFT. The electronic structures of these systems were investigated using the QMC methods. The calculations were carried out within the Variational (VMC) and fixed-node diffusion (DMC) quantum Monte Carlo methods. The calculations are also performed in the Hartree-Fock (HF) approximation in order to analyze the impact of electron correlation. With regards the aluminum hydride clusters, the total atomic binding energy impact varies from ~20% up to about ~50%, whereas for the electron binding energy it ranges from ~1% up to ~73%. The decomposition of the electron binding energies clearly shows that both charge redistribution and electron correlation are important in determining the detachment energies, whereas electrostatic and exchange interactions are responsible for the ionization potential. For the aromatic metal clusters, the presence of a dopant plays important role in their electronic properties enhancing their binding energy, electron affinity, hardness and resonance energy.Item Caracterizações óptica e elétrica de cristais de Bi2TeO5 crescidos por um método de duplo cadinho(Universidade Federal de Goiás, 2015-01-22) Fabris, Zanine Vargas; Carvalho, Jesiel Freitas; http://lattes.cnpq.br/5841291496427516; Carvalho, Jesiel Freitas; Baldochi, Sonia Licia; Santo, Ana Maria do Espírito; Lariucci, Carlito; Gonçalves, Pablo JoséBismuth tellurite, Bi2TeO5, here labeled BTeO has a lot of properties like improper ferroelectricity, photochromic, photorefractive, with two optical axes large optical window and another interesting optical and electrical properties, as recently we discovered, photovoltaic effect. BTeO single crystal growth and processing has two inherent difficulties, high vapor pressure of tellurium oxide close to bismuth tellurite melting point and BTeO cleavage plane parallel to (100) plane. So, BTeO factory good sample for material characterization require singular precautions and depends on researcher experience invariably. Present work is dedicated to detailed study of BTeO single crystals growth parameters in a modified Czochralski method with unpublished concept double crucible system. In our case, we used oxides mix on external crucible with volatile oxide bigger quantity related to internal crucible to create a supersaturated atmosphere used to control crystal growth liquid phase stoichiometry reducing tellurium oxide evaporation. We also highlighted important details about good quality samples production, like crystal cut and polish enclosed in acrylic resin to avoid cleavages during this processes. Finally, we characterized BTeO by optical spectroscopy (optical absorption, Raman scattering and luminescence) and electrical properties (conductivity, photoconductivity and impedance spectroscopy). We measured BTeO photorefractive properties with 633 nm wavelength for the first time and results suggested that material could be photovoltaic, hypothesis tested and confirmed in the present work.Item Estudo das propriedades estruturais e óticas de compostos aluminoboratos e aluminogermanatos puros e dopados com íons terras-raras(Universidade Federal de Goiás, 2017-04-12) Faria Filho, Fausto de Melo; Maia, Lauro June Queiroz; http://lattes.cnpq.br/9454054374479016; Maia, Lauro June Queiroz; Gonçalves, Pablo José; Santana, Ricardo Costa de; Gonçalves, Rogéria Rocha; Souza, Seila Rojas deThe objective of this thesis is study aluminogermanate and aluminoborate compounds containing lanthanide ions for photonic applications, especially light emitting diodes, as phosphors. Samples were prepared by sol-gel and polymeric precursor method (Pechini method). It was studied pure and doped Al6Ge2O13 with 1 mol% Eu3+ or Er3+ , heat treated at 1000 °C; 1 mol% Eu3+ doped xAl2O3+(1-x)B2O3, for x values: 0.33; 0.50; 0.60; 0.66; 0.75 and 0.80 under heat treatments at 800, 900 or 1000 °C; and the Al4B2O9 phase with xNd3+/ yYb3+, where x, y = 1, 0; 1, 1; 1, 2; 1, 4; 1, 8; 0, 1; 2, 1; 4, 1 and 8, 1, heat treated at 900 °C. The powders samples were characterized by X-ray diffraction, infrared vibrational spectroscopy, thermal analysis, and transmission electron microscopy. Diffuse reflectance spectra and photoluminescence emissions were collected under excitation at 394 nm for Eu3+ doped samples, at 378 and 977 nm for Er3+ doped samples, at 804 nm for Nd3+/Yb3+ doped samples and at 365 nm for pure samples. The Er3+ or Eu3+ doped aluminogermanate sample presented the Al6Ge2O13 crystalline phase identified by JCPDS card number 71-1061 after annealings at high temperatures. Absorption spectra in the infrared region showed Al-O-Ge and Al-O type bonds. The Eu3+ doped Al6Ge2O13 samples when excited at 394 nm showed red emission and the spectra analysis lead us to conclude that the lanthanides were located in a homogeneous environment with low symmetry. The Er3+ doped Al6Ge2O13 sample showed emission band in the infrared region with full width at half maximum of around 48 nm when excited at 977 nm. The band gap values were determined being between 4.19 and 4.30 eV. The Eu3+ doped xAl2O3+(1-x)B2O3 compositions presented the crystalline phase Al4B2O9 identified by JCPDS card number 29-0010. AlO6, AlO4, BO4 and BO3 groups were identified by FTIR technique. For these compositions, the emission spectra in the visible region showed a homogeneous environment with low symmetry. The Eu3+ doped 0.66Al2O3+0.34B2O3 sample possess the highest photoluminescence emission, after heat treatments at 900 °C . The lifetime of the Eu3+ 5D0 excited level were between 1.4 and 2.1 ms, depending on the B2O3 concentration and annealing temperature. The optical band gap was also determined having values between 3.72 and 4.42 eV. The Nd3+/Yb3+ doped Al4B2O9 samples present an efficient energy transfer between lanthanide ions and the best relative concentration was 1Nd3+ / 2Yb3+. The decay time of the emission at 1080 nm (975 nm) as function the Nd3+ concentration shows a maximum value around 120 μs at concentration of 4 mol% (around 200 μs for 2 mol%). On the other hand, changing the Yb3+concentration, the maximum decay time for emission at 1080 nm (975 nm) was around 100 μs (175 μs) for 1 mol% of Yb3+. In short, the materials studied are excellent candidates for application as luminophores in various technologies, such as LED´s and displays.Item Estudo das interações da miltefosina com membranas de L. (Leishmania) amazonensis e macrófagos peritoneais(Universidade Federal de Goiás, 2016-02-15) Fernandes, Kelly de Souza; Dorta, Miriam Cristina Leandro; ttp://lattes.cnpq.br/3933395097851681; Alonso, Antonio; http://lattes.cnpq.br/5013069863616789; Alonso, Antonio; Dorta, Miriam Cristina Leandro; Izumi, Erika; Souza, Paulo Eduardo Narcizo de; Oliveira, Valéria deMiltefosine (MT) is a alkylphospholipid originally developed for treatment of breast cancer and other solid tumors. It is currently used in the treatment of leishmaniasis, an infectious parasitic disease caused by protozoa of the genus Leishmania, being the first oral drug adopted for this purpose. However, its mechanism of action remains unclear. Electron paramagnetic resonance (EPR) spectroscopy of a spin-labeled lipid (5-DOXIL stearate) and a thiol-specific spin label (4-maleimido-TEMPO) in the membrane of axenic amastigotes of L.(Leishmania) amazonensis and peritoneal macrophages from Balb/c mice showed that MT causes significant increase in membrane dynamics at similar concentrations that inhibit parasite growth or are cytotoxic to macrophage. Although these alterations can be detected using a spin-labeled lipid, our experimental results indicated that MT interacts predominantly with the protein component of the membrane. Using a method for the rapid incorporation of MT into the membrane, these effects were measured immediately after treatment. Cytotoxicity, estimated via microscopic counting of living and dead cells, indicated ~80% parasites and macrophages death at the concentration of MT at which EPR spectroscopy detected a significant change in membrane dynamics. Cell viability, analyzed using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide tetrazolium) reduction assay, showed that 50% inhibitory concentration (IC50) of MT depends on the cell concentration used in the assay. This dependence was analyzed using a theoretical equation involving biophysical parameters such as the partition coefficient of watermembrane and MT concentrations on the membrane and in the aqueous medium. The data showed that cells more sensitive to MT are respectively: erythrocytes, Leishmania promastigotes and Leishmania amastigotes and macrophage. The IC50 value of MT for 4 x 107 parasites/mL was 24,35 M. For the same cell concentration, a significant alteration was detected in the membrane lipid fluidity of parasites to 15 M of MT. The EPR spectra of spinlabeled membrane-bound proteins were consistent with more expanded and solvent exposed protein conformations, suggesting a detergent-like action, with a possible formation of micelle-like structures around polypeptide chains.Item Simulações entrópicas do modelo de Bell-Lavis para a água(Universidade Federal de Goiás, 2020-04-07) Ferreira, Lucas de Souza; Caparica, Álvaro de Almeida; http://lattes.cnpq.br/4726638254587108; Caparica, Álvaro de Almeida; Rabelo, José Nicodemos Teixeira; Bakuzis, Andris Figueiroa; Chahine, Jorge; Barbosa, Marco Aurélio AlvesIn this work we used the entropic sample simulation to study the Bell-Lavis model for the liquid water. We estimed the joint density of states with which we obtain the average of the termodynamic properties of the energy, specific heat, density of particles, hydrogen bond energies, and the susceptibility of the density of particles to many values of the constants H and μ. Through of the analyze of this quantities we determined the possible ground states and the values for H and μ for which happen the transition between the ground states. We observe that for H = 1, 0 and 0, 0 < μ < 0, 5 the density of particles shows a maximum associated to transition from a configuration of low density to a configuration of high density. In this range the specific heat show two maxima, the first associated to maximum in the density, and do not shows finite size effects , and the second a transition order disorder. For 0.5 < μ < 1.5 we have only one maximum for the specific heat which is the fusion of the two before. We performed a finite size scaling study for μ = 1, 0 observing the thermodynamic quantities that characterize a second order fase transition and we found a critical temperature Tc = 0, 510718(49), while when observing the thermodynamic quantities that characterize a first order fase transition we obtain Tc = 0, 564520(37). Such results indicate the presence of two orders of phase transitions at very close temperatures. For understand the behavior we analise the order parameter to the one dimensional Ising model and conclude that the right choice of the order parameter for the model is decisive to visualize the phase transition. For the Bell-Lavis model the choice of this parameter is yet a challenge to be overcome.
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