http://hdl.handle.net/11422/59 2026-05-07T03:23:32Z 2026-05-07T03:23:32Z Leal, Ana Beatriz Alves http://hdl.handle.net/11422/29142 2026-05-06T19:47:02Z 2026-02-23T00:00:00Z

Title: Determinação qualitativa e quantitativa de sangue oculto em fezes humanas, através do kit luminol-UFRJ: um teste não invasivo para rastreamento de lesões gastrointestinais Author(s)/Inventor(s): Leal, Ana Beatriz Alves Advisor: Lopes, Claudio Cerqueira Abstract: The detection of occult blood in stool (FOB) is one of the main non-invasive strategies for screening gastrointestinal diseases, especially those associated with inflammatory, hemorrhagic, or neoplastic processes. This study presents the development and evaluation of an innovative analytical method based on the Luminol Kit produced by the Laboratory for Synthesis and Analysis of Strategic Products (LASAPE/UFRJ), traditionally used in forensic applications due to its ability to emit chemiluminescence in the presence of hemoglobin. The proposal consists of adapting the use of luminol to detect small concentrations of occult blood in fecal samples, exploiting its high sensitivity and potential for rapid and low-cost analysis. The method developed is qualitative and quantitative in nature, incorporating a simple, economically accessible, and easy-to-execute approach, with a view to its use in laboratory and clinical environments. The quantification of hemoglobin concentrations in the samples was performed using computerized densitometry, allowing for the systematic evaluation of essential parameters such as sensitivity, accuracy, and diagnostic capacity. In addition, the performance of the proposed method was qualitatively compared to the immunochromatographic test, currently the most widely used procedure in routine fecal occult blood screening. By enabling the quantification of fecal hemoglobin in patients with different gastrointestinal conditions, this study seeks to demonstrate the potential of the luminol-based method as an alternative tool for early diagnosis and therapeutic monitoring. Thus, the research aims to contribute to the development of innovative, non-invasive, and low-cost strategies capable of offering greater sensitivity, operational simplicity, and applicability in medical practice, especially in relevant diseases such as inflammatory bowel disease and colorectal cancer. Publisher: Universidade Federal do Rio de Janeiro Type: Dissertação

2026-02-23T00:00:00Z Jesus, Victor Freitas de http://hdl.handle.net/11422/29141 2026-05-06T19:25:38Z 2025-06-30T00:00:00Z

Title: Desenvolvimento e aplicação de metodologia de desgaste controlado de aço galvanizado para ensaios de corrosão atmosférica em campo Author(s)/Inventor(s): Jesus, Victor Freitas de Advisor: Salles, Maiara Oliveira Abstract: This dissertation shows the development and application of an innovative methodology for controlled wear of galvanized steel, aiming field atmospheric corrosion tests. Galvanized sample preparation generated three different groups according to different carbon steel surface treatment: dry steel grit blasting (group G), dry glass bead blasting (group V) and mill scale acid pickling (group C). The experimental approach used design of experiments (DoE) to decide wear methodology. Preliminary assays were performed to determine initial evaluation parameters, getting to two viable wear types: chemical and physical. Tested variables were solution concentration and immersion time for chemical wear, and flap disc grit and contact time of flap disc with sample surface for physical wear. Screenings and optimization assays were based on full factorial design of experiment (𝑛𝑘) with triplicate at the central point. The aimed goal was 50% reduction of the original galvanized layer, relating this value to mass variation according to each kind of wear. Galvanized compliance tests were performed, as well as electrochemical techniques to evaluate worn surfaces compared to non-worn surfaces. Results indicated that the optimized chemical wear was the most promising, validated with 95% accuracy. Complementary assays allowed a better understanding of the surface wear techniques used. The first data for corrosion rate indicated the possibility to create better predictive models for atmospheric corrosion aiming the electric sector. This work contributes to establish better benchmarks for preventive maintenance, as well as more accurate analysis of extending the service life of galvanized metal structures. Publisher: Universidade Federal do Rio de Janeiro Type: Dissertação

2025-06-30T00:00:00Z Oliveira, Patrick Marques de http://hdl.handle.net/11422/29140 2026-05-06T18:52:45Z 2026-02-11T00:00:00Z

Title: Fragmentação de ésteres em fase gasosa por impacto de elétrons Author(s)/Inventor(s): Oliveira, Patrick Marques de Advisor: Pereira, Maria Luiza Rocco Duarte Abstract: This work presents an experimental/theoretical investigation into the ionization and fragmentation of three esters: methyl formate, methyl acetate, and ethyl acetate. Time-of-flight mass spectrometry was applied across a wide range of electron impact energy, from 12 eV to 800 eV. To convert the fragment cross-sections obtained relative to the not dissociated molecular ion and determine the total absolute ionization cross-section the Binary-Encounter-Bethe methodology was used. Both experimental and theoretical results were compared with available data. It was found that the molecular structure and dissociation pathways significantly alter the production of various common fragments among the molecules. An increase in both partial and total absolute cross-sections was observed as a function of electron impact energy, which is strongly dependent on the chain length. The extension of the molecular chain implies a greater number of valence electrons and, therefore, more molecular orbitals and excited levels reached by ionization participating in the dissociation process. The data allowed for a comparison between the maximum total ionization cross-section and the volumetric polarizability, revealing a linear behaviour as proposed in the literature for organic compounds, which suggests the validity of the present calculations. This study is of interest to astrochemistry, particularly astrobiology. Specifically, the interstellar medium (ISM) contains organic molecules, including esters essential for the evolution and chemical diversity of a stellar system. The matter within the ISM, found in heterogeneously distributed gas and dust clouds, is processed by ionizing radiation, including electron incidence, forming complex molecules based on carbon, hydrogen, and oxygen. Publisher: Universidade Federal do Rio de Janeiro Type: Dissertação

2026-02-11T00:00:00Z Costa, Marília Ladeira Alves e http://hdl.handle.net/11422/29138 2026-05-06T18:25:17Z 2026-01-01T00:00:00Z

Title: Uso de métodos DFT e de docking molecular para avaliar a quelação de átomos de Ferro em grupos [Fe4S4(Cys)4]-2 Author(s)/Inventor(s): Costa, Marília Ladeira Alves e Advisor: Lima, Camilo Henrique da Silva Abstract: This work aims to perform a critical analysis of the ability of molecular docking methods to describe electronic interactions in metalloenzymes containing [4Fe–4S] clusters. The study employs Density Functional Theory (DFT) calculations and docking simulations to investigate systems in which metal–ligand interactions require explicit consideration of electronic effects, which are often neglected by classical methods. The methodology initially involved DFT calculations on [4Fe–4S] cluster models coordinated by cysteine residues to evaluate the energetic favorability of ligand coordination. Subsequently, docking studies were carried out on different protein systems using AutoDock4, LeDock, AutoDock Bias, and Metalloprotein Bias Docking, under RESP and AM1-BCC partial charge schemes, in addition to cavity analyses to assess site accessibility. The results demonstrate that, although the search algorithms generate poses with low RMSD values in redocking protocols, the scoring functions consistently fail to reproduce realistic coordination geometries. Excessively short metal–oxygen distances and incorrect orientations of coordinating atoms were favored, regardless of the applied bias or charge scheme. It is concluded that the main limitations of classical docking methods in metalloprotein systems are intrinsically associated with deficiencies in the scoring functions. Publisher: Universidade Federal do Rio de Janeiro Type: Dissertação

2026-01-01T00:00:00Z