Mestrado em Física (IF)
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Item Estudo das interações dos surfactantes iônicos SDS, CTAC e HPS e miltefosina com membranas de leishmania, macrófagos e eritrócitos(Universidade Federal de Goiás, 2023-09-18) Cardoso, Éder Jéferson Souza; Alonso, Antônio; http://lattes.cnpq.br/5013069863616789; Alonso, Antônio; Mendanha Neto, Sebastião Antônio; Silva, Kleber Santiago Freitas eMiltefosine (MT) is an internationally approved oral drug for the treatment of leishmaniasis, however, its mechanism of action is not yet well established. Understanding the mechanism of action of compounds with leishmanicidal activity is important to help in the search for new drug prototypes with greater activity and fewer side effects. Surfactants are compounds widely used in the industry in the manufacture of soap, shampoos and other cosmetics. They are usually classified according to the molecular charge, and may be nonionic, anionic, cationic or zwitterionic (or amphoteric) when they have a positive and negative charge in the same compound. Electron Paramagnetic Resonance (RPE) spectroscopy associated with the spin-label method was used to compare the interactions of MT and the surfactants Sodium Dodecyl Sulfate (SDS, anionic), Cetyl Trimethyl Ammonium Chloride (CTAC, cationic) and N, N-dimethyl-3-ammonio-1-propanesulfonate (HPS, zwitterionic) with the membranes of Leishmania (L.) amazonensis, erythrocyte and macrophage. All compounds increased the molecular dynamics of membrane proteins; however, SDS caused the smallest increase in parasite and erythrocyte membrane dynamics and was also the least effective in antileishmanial activity, cytotoxicity in macrophages J774.A1 and hemolytic potential in both PBS and whole blood. It was detected, in blood plasma, the albumin stiffness caused by 2.5 mM SDS due to the electrostatic and hydrophobic interactions of the compound with the protein. CTAC did not show significant differences in relation to the other compounds, but at higher cell concentrations (>1x109 cells/mL), it showed high activity against the L. amazonensis promastigotes, besides being the most cytotoxic to macrophages J774.A1. For all the experiments, the zwitterionic molecules HPS and MT did not present significant differences between them. The data suggest the possibility of using cationic or zwitterionic surfactants in formulations containing leishmanicides, aiming at the treatment of cutaneous leishmaniasis.Item The dynamical Casimir effect and the generation of thermodynamic entropy(Universidade Federal de Goiás, 2024-03-12) Oliveira, Gustavo de; Céler, Lucas Chibebe; http://lattes.cnpq.br/6630683190018665; Céler, Lucas Chibebe; Landi, Gabriel Teixeira; Maia Neto, Paulo AméricoIn this dissertation, we investigate the dynamics of the thermodynamic entropy production in the dynamical Casimir effect. This is done by considering a quantum scalar field confined by a one-dimensional cavity composed of a pair of ideal mirrors, one fixed and the other allowed to move in a prescribed trajectory. The central goal of this work is to understand how the thermodynamic entropy of the field evolves over time due to the particle creation process induced by the non trivial boundary conditions imposed by the moving mirror. By employing an effective Hamiltonian approach, the system’s entropy production is shown to increase with the number of particles created within the short-time limit. Moreover, one can also demonstrate that this approach is directly related to the generation of quantum coherence in the energy basis of the field. Utilizing a distinct method, grounded in the theory of Gaussian states, we were able to analyze the long-time limit of the entropy production for a single mode of the field. The obtained results establish a relationship between the increase in thermodynamic entropy in the field mode and the entanglement between the considered mode and the rest of the field mode structure. In this way, we link the entropy production in the field due to the dynamical Casimir effect with two fundamental features of quantum mechanics: quantum coherence and entanglement.Item Estudos de materiais dopados com íons lantanídeos para aplicações em nanotermometria(Universidade Federal de Goiás, 2023-10-31) Silva, Daniel Lopo da; Maia, Lauro June Queiroz; http://lattes.cnpq.br/9454054374479016; Maia, Lauro June Queiroz; Poirier, Gaël Yves; Santana, Ricardo Costa deOptical phenomena such as luminescence of materials depend on several characteristics such as temperature, dopants, crystalline structure, etc. Electromagnetic emissions from materials doped with rare-earth ions can provide thermal information regarding the environment where these materials are inserted. Materials with good thermal sensitivity are considered promising for the development of technologies for nanoscale temperature measurements. In this work, nine samples previously prepared through different synthesis routes such as sol-gel process and modified Pechini were analyzed. The samples studied have matrices of several compounds such as aluminum borates (Al4B2O9) monophasic and embedded in silica, aluminum germanates (Al6Ge2O13) monophasic and embedded in silica, yttrium borates (YBO3) and yttrium aluminum silicates (YAS). Altogether, five trivalent lanthanide ions were used as dopants of the samples: Nd, Eu, Er, Tb and Yb. The emission spectra of the samples were analyzed at seven different temperatures from 25 °C to 55 °C with a variation of 5 °C. Diffuse reflectance spectra were studied to confirm the presence of ions in the matrix and enable the calculation of the energy gap for each sample. From the emission spectrum, photoluminescent intensity ratios (RIFs) were calculated for the calculation of relative thermal sensitivities. The sample that showed the highest value for relative thermal sensitivity (Sr) was the one with the composition YBO3 : Nd3+, Eu3+, Er3+, Yb3+, Tb3+ synthesized at 900°C, presenting a value of Sr = (1,52 ± 0,20) %.K-1 in the temperature range of 35°C and 55°C.Item Entropy production in quantum systems and Nernst heat theorem for a single qubit(Universidade Federal de Goiás, 2024-02-23) Sousa, Aryadine Fernandes de; Almeida, Norton Gomes de; http://lattes.cnpq.br/3182841849332242; Almeida, Norton Gomes de; Souza, Alexandre Martins de; Moraes Neto, Gentil Dias deClassical thermodynamics, which focuses on macroscopic systems in equilibrium, has given rise to various theories to address systems out of equilibrium over time. Recently, quantum thermodynamics has emerged as a theory dedicated to describe microscopic quantum systems. A notable application of this theory is found in the development of thermal engines, where the working substance is a microscopic quantum system. In this work, we present the essential theoretical formulation to understand entropy production in quantum systems and its impact on thermal machines. The approach involves exploring quantum friction and conducting a deeper analysis of the laws of thermodynamics on a fundamental scale. Examining the effects of these phenomena in a Quantum Otto Heat Engine, we highlight the implications of quantum friction on engine performance. Particularly noteworthy is the observation that operating the cycle with a reservoir with effective negative temperature enhances the engine efficiency significantly. This improvement is attributed to strategic choices in the populations of excited states in the reservoirs, revealing an innovative approach to optimizing performance in quantum systems. Additionally, we extend the Nernst heat theorem for a single qubit. This result not only presents intriguing theoretical implications but is also supported by numerical simulations and experiments using Nuclear Magnetic Resonance (NMR). These pieces of evidence uphold the remarkable convergence of Helmholtz free energy and internal energy as the temperature approaches zero Kelvin, underscoring the practical applicability of these theorems in quantum systems.