DSpace Coleção:http://repositorio.ufc.br/handle/riufc/3102024-03-28T22:16:29Z2024-03-28T22:16:29ZO uso do glicerol para a obtenção de produtos de alto valor agregado via biocatáliseSousa Junior, Paulo Gonçalves dehttp://repositorio.ufc.br/handle/riufc/763462024-02-29T18:52:51Z2023-01-01T00:00:00ZTítulo: O uso do glicerol para a obtenção de produtos de alto valor agregado via biocatálise
Autor(es): Sousa Junior, Paulo Gonçalves de
Abstract: Eversa® Transform 2.0 is a lipase derived from Thermomyces lanuginosus produced by a genetically modified microorganism. It has a low production cost, high substrate specificity, and high catalytic activity in organic synthesis. Glycerol is a subproduct of the biodiesel industry, and in this research, glycerol is used to produce glycerides. The Taguchi method was used to evaluate the best conditions for the enzymatic esterification of glycerol with acetic acid. A yield of 84.8% was obtained, under the optimal conditions (temperature = 40 ◦C; molar ratio glycerol/acid = 1:1; biocatalyst = 15% w/w; time = 12.5 h). After the statistical analysis, the temperature was found to be the most significant parameter influencing the reaction conversion. A theoretical study was carried out to generate a homology model of the enzyme, based on other natural lipases. Molecular docking, molecular dynamics, and QM/MM simulations were applied to understand the mechanism of esterification and to derive thermodynamic and kinetic data. The nucleophilic attack step was identified as the rate-limiting step for both acylation (13.1 kcal/mol) and deacylation (13.8 and 12.9 kcal/mol) reaction mechanisms. Although the enzyme is capable of esterifying all three alcohol groups of glycerol, the esterification of the primary alcohols is thermodynamically more favorable (5 kcal/mol), especially at higher temperatures.
Tipo: Dissertação2023-01-01T00:00:00ZEletrodeposição de revestimentos de Fex-Nix-1 de alta área e avaliação de sua atividade eletrocatalítica para a reação de desprendimento de hidrogênio em meio alcalinoDantas, Valdessandro Fariashttp://repositorio.ufc.br/handle/riufc/762622024-02-23T20:29:33Z2023-01-01T00:00:00ZTítulo: Eletrodeposição de revestimentos de Fex-Nix-1 de alta área e avaliação de sua atividade eletrocatalítica para a reação de desprendimento de hidrogênio em meio alcalino
Autor(es): Dantas, Valdessandro Farias
Abstract: This work aims to produce porous Fe, Ni and Fe-Ni electrocatalysts for the production of hydrogen from the electrolysis of water in an alkaline medium. All electrocatalysts were prepared in an acidic soluction, under constant stirring, at a temperature of 333 K and galvanostatic electrodeposition in an aqueous soluction at a current density of 5 mA cm−2. Electrolytes containing Fe and Ni at different molar ratios were used. For morphological and electrocatalytic evaluations, the following techniques were used, respectively: scanning electron microscopy (SEM), flame atomic absorption spectrometry (FAAS), cyclic voltammetry (CV), linear scanning voltammetry (LSV) and stability tests in continuous operation. As a result, all electrocatalysts obtained presented porous surface morphology. As for the electrocatalytic tests, they all presented electrochemically active area (ECSA) values between 1107 and 6245 cm², with the electrodeposits with the highest Fe content being those with the highest value. The kinetic parameters suggest that electrodeposits with higher Fe content have more positive overpotential values and charge transfer kinetics that are more favorable to the hydrogen release reaction (RDH). Finally, stability tests suggested good adhesion of the electrodeposits during an operating time of 40 hours and a temperature of 333 K, with potential values remaining stable between –200 and –400 mV.
Tipo: Dissertação2023-01-01T00:00:00ZEmulsões com colágeno extraído de resíduo do beneficiamento de Tilápia com extrato de Phyllanthus niruri com propriedade antioxidanteLima, Grazielly Cardosohttp://repositorio.ufc.br/handle/riufc/755882024-01-04T12:34:57Z2018-01-01T00:00:00ZTítulo: Emulsões com colágeno extraído de resíduo do beneficiamento de Tilápia com extrato de Phyllanthus niruri com propriedade antioxidante
Autor(es): Lima, Grazielly Cardoso
Abstract: Emulsions are systems composed of two immiscible liquids, thermodynamically unstable and with a particle diameter greater than 200 nm. Due to the pleasant sensory properties, low irritability, optimum moisturizing, spreadability, in addition to rapid penetration of skin images, they have attention of the various areas of study. Therefore, this work presents collagen emulsions extracted from Nile Tilapia (Oreochromis niloticus) processing residues for the incorporation of aqueous extracts of dry leaves the Phyllanthus niruri. Collagen was extracted from the demineralized Tilapia scales by the enzyme method and by the aqueous extract of Phyllanthus niruri, being used as an aqueous extractor of pressurized solvent (ASE). Stable emulsions with the combination of olive oil, sorbitan monooleate and polysorbate 80 by the high energy method using tip ultrasound. The stability was analysed by macroscopic, centrifugation, pH, zeta potential, polydispersity and electrical conductivity. The EHL value required for sunflower oil is studied and recorded equal to 7.0. To determine thebest formulation, a ternary diagram was constructed,noting that the experimente 29 (80% water, 10% surfactant and 10% oil), showed greater stability. Primary testes the emulsion containing collagen (0.1%, 0.25%, 0.5%, 0.75% and 1%) were done. The emulsions containing 0.1% and 0.5% obtained the highest macroscopic stability, even after centrifugation, but the size was 634.6 and 715.1 nm, respectively. Several other emulsions were formulated until arrive an F'1 emulsion, added to the aqueous Phyllanthus extract. In this emulsion, in addition to the stability tests, cytotoxic activity was carried out against tumor lines of the uterine colon, prostate, leukemia and astrocytoma. This in vitro activity studies, showed activity, however, it is necessary to review tests with higher concentrations, aiming to improve their cytotoxic action.
Tipo: Dissertação2018-01-01T00:00:00ZDesenvolvimento de método analítico para determinação de Hg em amostras biológicas utilizando técnica de geração fotoquímica de vapor acoplada à espectrometria de absorção atômicaAndrade Neto, Renato Sampaiohttp://repositorio.ufc.br/handle/riufc/753662023-12-19T14:30:22Z2019-01-01T00:00:00ZTítulo: Desenvolvimento de método analítico para determinação de Hg em amostras biológicas utilizando técnica de geração fotoquímica de vapor acoplada à espectrometria de absorção atômica
Autor(es): Andrade Neto, Renato Sampaio
Abstract: Photochemical vapor generation (PVG) is an analytical technique used to convert elements into volatile species to improve the efficiency of the transport of this analyte to the detection system. In this work, analytical procedures were developed for the determination of Hg in samples of certified reference material (DORM-2, TORT-2 and Oyster Tissue) and samples of cerebellum and abdominal fat of rodents submitted to Hg contamination protocol for determination by atomic absorption spectrometry (AAS). The analyte was extracted from the samples using solubilization in formic acid. The method was optimized using full factorial design with axial points using as variables: the UV irradiation time, the formic acid concentration and the gas flow and as respons the integrated absorbance. Concentrations found in the cerebellum samples were 2863,01 ± 0,05 mg kg-1 and 776,4 ± 0,08 mg kg-1 in the abdominal fat samples. The method developed showed limits of detection and quantification equal to 0.04 μg kg-1 and 0.12 μg kg-1, respectively. The accuracy of the method was statistically proven through the analysis of certified reference material. The present method proved to be an efficient alternative for the analysis of Hg in samples of animal origin, aligning the increase of sensitivity with the photochemical generation of vapor, in addition to respecting the principles of green chemistry.
Tipo: Dissertação2019-01-01T00:00:00Z