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1
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GLAUBER ANTONIO ALBUQUERQUE DOURADO
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REACTIVITY OF 2-AMINO-1,4-NAFTOQUINONE IN HANTZSCH REACTIONS: TRICOMPONENT SYNTHESIS OF FUNCTIONALIZED AZAPOLICYCLES
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Leader : SILVIO DO DESTERRO CUNHA
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MEMBRES DE LA BANQUE :
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JORGE MAURICIO DAVID
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LOURENCO LUIS BOTELHO DE SANTANA
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SILVIO DO DESTERRO CUNHA
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Data: 1 févr. 2019
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Afficher le Résumé
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The aim of this work was to develop nitrogenous heterocyclic synthesis methodologies, based on the Hantzsch methodology, from multicomponent reactions that were adapted to the principles of green chemistry. The main building block studied was 2-amino-1,4-naphthoquinone, a molecule that has the characteristic of the junction of a quinone nucleus and the enaminone portion. The synthesis of pyrimido- [4,5-b] -quinoline-tetraones derivatives, took special note because these types of molecules have proven biological properties. A novel synthetic route was developed in a trichomponent form using a mixture of 2-amino-1,4-naphthoquinone, benzaldehyde derivatives and barbituric acids, various conditions were tested, and the best result was obtained using reflux in acetonitrile and aminosulfonic acid as catalyst for the synthesis. This new methodology creates another option for the synthesis of this product. By replacing the reaction solvent with ethanol and removing the catalyst to adapt the process to the principles of green chemistry, a new reaction pattern was observed producing unpublished molecules, dihydrobenzo [g] pyrimido [4,5-b] quinoline-tetraone were obtained with the formation of an exocyclic double bond, other than the pyrimido- [4,5-b] -quinolines-tetraones, where this double bond is endocyclic, the synthesis of arylidene in Meldrum's acid was studied, degradation of this acid after 24h at reflux with ethanol. The reaction for the production of the 13phenyl-6,13-dihydro-6-azapentacene-5,7,12,14-tetraone analogs was proposed by our GPSQ research group and then we developed a new proposal that replaces Meldrum acid with malonic acid, reaction with similar yields.
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2
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ANA CLARA RODRIGUES DE MAGALHÃES
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GAS REAGENTS PRODUCTION BY PERSULFATE THERMAL DECOMPOSITION AND ITS EFFECTS ON EDIBLE VEGETABLE OILS SAMPLE PREPARATION.
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Leader : RODOLFO DE MELO MAGALHAES SANTANA
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MEMBRES DE LA BANQUE :
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RODOLFO DE MELO MAGALHAES SANTANA
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DANIELE CRISTINA MUNIZ BATISTA DOS SANTOS
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MADSON DE GODOI PEREIRA
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Data: 5 avr. 2019
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Afficher le Résumé
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Sample preparation step usually implies in high costs and time consumption, in despite of its important play holed in analytical results quality. In this sense, development of new sample preparation strategies that increase analytical throughput and provide more sensitive and accurate analytical methods has being a subject of interest. Thus, the present work aiming to develop a new sample preparation based on the production of insitu reagents from ammonium persulfate decomposition irradiated by microwave in a closed system for the analysis of samples with high-unsaturated fat content. The decomposition parameters, concentration of HNO3 (3.5 to 14.0 mol L-1), decomposition temperature (150 to 210 °C) and decomposition time (23 to 40 min) were evaluated to ensure decomposition efficiency as well as higher in-situ reagent production rate. Therefore, 8 mL of HNO3 were added to safflower oil samples (m ≈ 0.250 g) in presence or absence of auxiliary decomposition vial containing (NH4)2S2O8 solution (2.0 mol L-1). Persulfate effects on digestion step were evaluated by comparison with procedures performed using only HNO3 taking the dissolved carbon content (DOC) as analytical response. The proposed method was applied to samples of edible oils from safflower, coconut, flaxseed and chia to elemental analysis. Decomposition optimum conditions with persulfate indirect application were set at 210 °C with irradiation time of 40 min and HNO3 concentration equal to 7.0 mol L-1. Reagents in-situ generation by persulfate thermal decomposition led to a greater sample solubilization and clearer digested in face of those obtained only using HNO3. However, the chemical evidences obtained from final digested in both procedures indicated that byproduct gas produced by persulfate thermal decomposition did not act as auxiliary oxidizing reagents. Under optimum conditions, DOC levels were equal to 0.61 ± 0.02 and 2.2 ± 0.4 g L-1 in nitric/persulfate and nitric digested, respectively. In addition, a significant difference was observed in relation to the digested obtained when persulfate was applied directly to the sample (2.9 ± 0.3 g L-1). The proposed method presented good accuracy with results in agreement with FDA U.S. Food and Drug Administration reference Method (p = 0.05). In addition, good precision (RSD <10%, N= 7) was found, with wide linear ranges and good linearity (R2≥ 0.999) and LOD ranging from 0.0005 to 0.096 mg L-1. The proposed method allowed the determination of As, Ca, Cd, Cr, Fe, Mn, Na, Ni, P, Pb, Se and Zn in edible vegetable oil samples by ICP OES and ICP-MS. However, it was verified systematic errors occurrence to Cu, for all evaluated oils, and Fe in safflower oil. Thus, (NH4)2S2O8 indirectly use has proved to be an alternative method to nutrients and contaminants determination in edible vegetable oil samples with good analytical productivity, accuracy and precision.
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3
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JOÃO CARLOS SILVA CONCEIÇÃO
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In vitro and in silico studies of biotransformations of phenolic substances
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Leader : ELIANE DE OLIVEIRA SILVA
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MEMBRES DE LA BANQUE :
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ELIANE DE OLIVEIRA SILVA
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JORGE MAURICIO DAVID
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SAMUEL SILVA DA ROCHA PITA
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Data: 3 mai 2019
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Afficher le Résumé
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Biotransformation processes have an important role in chemical derivatization since the enzymes and their cofactors are generated in situ, acting as efficient catalysts that modify different substrates. In general, biotransformation reactions present high selectivity and are according to the Green Chemistry principles. Phenolic substances have numerous bioactivities and are useful for several industries to producing derivatives with high added value. Within this context, in the present study, the biotransformations of three phenolic substances were analyzed using two strains of filamentous fungi: Trametes versicolor ATCC 200801 and Aspergillus brasiliensis ATCC 16404. The fungus T. versicolor is a traditional source for the enzyme laccase (an oxidoreductase). The chemical profiles of the biotransformations were evaluated by using Thin Layer Chromatography (TLC), High-Efficiency Liquid Chromatography coupled to Diode Array Detector (HPLC-DAD) and Gas Chromatography coupled to Mass Spectrometry (GC-MS), and the most promising processes for the biotransformation of the evaluated substrates were selected. The obtained derivatives were isolated by chromatographic column using silica gel as the stationary phase and ethyl acetate, hexane and methanol as the mobile phase. Spectroscopic and spectrometric techniques were used to determine the chemical structures of the derivatives. It was possible to observe that T. versicolor biotransformed only methyl p-coumarate, resulting in the formation of three derivatives: cumaric acid, yield of 12.18 %; methyl caffeate, yield of 3.56%; and (E)-methyl-3- (4-methoxyphenyl) acrylate (identified in mixture). Biotransformations by A. brasiliensis resulted in the conversion of methyl p-coumarate into three derivatives (detected by GC-MS): acetophenone, 1-(4-hydroxyphenyl) propane-1,3-diol and 4-(3-hydroxypropyl) benzene-1,2-diol; methyl ferulate was biotransformed into (4)-methyl-3-(4-hydroxy-3-methoxyphenyl)-3-methoxyacrylate (10.31 % yield). Additionally, the biotransformation of the three phenolic substrates by T. versicolor was studied by in silico assays. It was considered that the enzyme present in the reaction medium was laccase and the molecular docking was carried out. The AutoDock v.4.2 and Pymol softwares provided a prediction of the orientation and preferential conformation that the phenolic substrates took on the active site of laccase. The results indicated that the three substrates interacted spontaneously with the biological receptor, but with different free energy values (ΔG): ΔG p-methyl coumarate = -6.89 Kcal.mol-1, ΔG methyl ferulate = -7, 37 Kcal.mol-1 and ΔG methyl caffeate = -7.55 Kcal.mol-1. The ligand-protein complex consisting of methyl p-coumarate-laccase was the least stable one, explaining the occurrence of biotransformation of this substrate by T. versicolor. Thus, it was possible to demonstrate that methyl p-coumarate interacted more efficiently with the laccase site, allowing the occurrence of hydrolysis, hydroxylation and methoxylation reactions.
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4
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HEMERSON DANTAS DOS SANTOS
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Chemometric analysis of NMR data of coffee from the Chapada Diamantina region (state of Bahia, Brazil)
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Leader : ELISANGELA FABIANA BOFFO
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MEMBRES DE LA BANQUE :
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ELISANGELA FABIANA BOFFO
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PAULO ROBERTO RIBEIRO DE JESUS
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GISELE ANDRE BAPTISTA CANUTO
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ROSILENE APARECIDA DE OLIVEIRA
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LOURDES CARDOSO DE SOUZA NETA
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Data: 3 mai 2019
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Afficher le Résumé
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The coffee from the Chapada Diamantina region, in the state of Bahia, Brazil, are considered high quality, due to the use of adequate production and processing criteria throughout the entire process, has provided this food with a high degree of quality and excellence, which is directly linked to its final chemical complexity. Studies about the chemical profile of coffee have correlated chemical composition, quality standards and data about geographical origin, thus contributing to antifraud methodologies. This research used Nuclear Magnetic Resonance (NMR) to study the chemical composition of coffee from Chapada Diamantina, in order to contrast them to coffee from other regions. We analyzed 37 commercial samples, which are classified, accordingly to their quality, as traditional, superior and gourmet. 1H NMR spectra were acquired on the Varian Inova 500 spectrometer of the Laboratório Baiano de Ressonância Magnética Nuclear (LABAREMN/UFBA). Analyzing the NMR data, we identified characteristic signals of chlorogenic acids (CGA), such as caffeoylquinic acids [6.74 - 6.80 m], alkaloids and xanthines as trigonelline [4.43 s] and caffeine [3.24 s, 3.41 and 3.84 s]. We also observed characteristic signals of furans (5-HMF [9.44 s]), amides and amino acids such as acrylamide [5.83 and 5.99 m] and L-alanine [1.39 d (6 Hz)]. Finally, we identified signals of organic acids, such as lactic acid [1.35 d (7 Hz)] and acetic acid [1.96 s], as well as carbohydrates and lactones, such as myo-inositol [3.27 - 3.35 m] and γ-butyrolactone [2.15 - 2.18 (m)]. The pretreatment of the 1H NMR spectra was made using alignment, autoscaling, and normalization (norm one). Then, the principal components analysis was performed. In the PCA scores plot, we observed four groups, which were denominated Chapada Diamantina, Bahia, Brazil and gourmet/superior. The coffee from Chapada Diamantina presented a characteristic chemical profile, which distinguished them from the others, mainly because they contain higher levels of lipids. The coffee from that region which present highest commercial value and which are classified as gourmet were grouped with Colombian coffee and some national ones with similar quality standards. This group presented higher levels of chlorogenic acids and trigonelline, substances which contribute to the pleasant aroma and taste of the beverage. The chlorogenic acid signals of coffee from other regions of the state of Bahia showed very low intensities. Coffee from other Brazilian states presented higher quinine levels in comparison than those from Bahia, and lower levels of chlorogenic acids than those from Chapada Diamantina. The results show that 1H NMR, coupled with chemometrics, is a very effective tool to discriminate coffee, allowing us to obtain from the data set as much information as possible, and to highlight its most important pieces. This methodology, whose efficiency has been proved by various studies, can help us understand complex mixtures.
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5
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KLEBER OLIVEIRA VISCARD JUNIOR
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STUDY OF THE JOANES RIVER BASIN WATER QUALITY EVOLUTION
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Leader : VANIA PALMEIRA CAMPOS
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MEMBRES DE LA BANQUE :
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VANIA PALMEIRA CAMPOS
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LEONARDO SENA GOMES TEIXEIRA
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LUCIANO MATOS QUEIROZ
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Data: 3 juin 2019
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Afficher le Résumé
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The Joanes River Basin is an important spring located in the Metropolitan Region of Salvador and responsible for about 40% of the water supply of the city of Salvador and the region. Despite this, the environmental aggressions that the river Joanes and its tributaries have been suffering, such as the dumping of domestic and industrial sewage, destruction of riparian forests, undue land occupation, among others, are daily actions suffered by them and can greatly impact the quality of its waters. This work sought to study the evolution of the water quality of this basin over the years 2008 to 2017, through the analysis of physicochemical parameters such as pH, dissolved oxygen, turbidity, among others, and analysis of metals such as cadmium, lead, copper, chromium, nickel and zinc, determined by ICP OES. The data obtained were used to calculate indexes such as WQI (Water Quality Index), TSI (Trophic State Index) and WLI (Aquatic Life Preservation Index), which are used to classify waters according to their quality. According to the calculated indexes, there are variations in the classification of waters that indicate "optimal" quality to "very bad" along the course of the river and its tributaries. It also showed that there was no significant variation in water quality over the years, however, it presents a negative evolution by considering the course of the river from the source to the mouth. By making a comparative approach between the IQA and IVA indexes, the inefficiency of using the IQA as a tool for assessing the quality of the Basin is evidenced, considering that, in more than 70% of the points sampled, the classifications were inconsistent with the presented in the IVA, which uses indisputable parameters of significance, such as the concentration of toxic chemical contaminants. In addition, in more than 80% of the points sampled, there was a violation of the parameters regulated for class 2 fresh waters, in accordance with CONAMA Resolution 357/05. In this way, it is expected that this work serves as a document to encourage concrete actions by the government, aiming, in an emergency time, to reverse the harmful anthropic emissions that have been degrading for a long time the quality of the waters of the Joanes River Basin.
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6
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Leonardo de Oliveira Aguiar
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5,8-π-EXTENDED QUINOXALINE DERIVATIVES AS GOOD CHROMOFORMS FOR PHOTOLUMINESCENCE APPLICATIONS
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Leader : ANDRE ALEXANDRE VIEIRA
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MEMBRES DE LA BANQUE :
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ALOIR ANTONIO MERLO
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ANDRE ALEXANDRE VIEIRA
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MAURICIO MORAES VICTOR
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SILVIO DO DESTERRO CUNHA
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Data: 14 juin 2019
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Afficher le Résumé
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In this work, the synthesis, characterization and the study of thermal and photophysical properties of liquid-crystalline materials containing quinoxaline heterocycle are described, whose derivatives are known to present good performance in the construction of polymers, OLEDs and exhibit pronounced biological activity. To obtain new liquid crystals it is proposed the functionalization this heterocycle at positions 5 and 8, varying the coupled peripheral groups as a function of the alkyl chain length. The structural characteristics of the proposed molecules are capable of presenting calamitic mesomorphism and luminescent properties. The synthetic route to prepare the final compounds begins with the 4,7-dibromo-2,1,3-benzothiadiazole compound, involves reductive sulfur extrusion reaction, followed by cyclization using glyoxal. The final step of Sonogashira cross-coupling reaction allows obtaining the desired π-extended compounds. The synthesized molecules were characterized by spectroscopic techniques. The thermal properties were evaluated by DSC, TGA and MOLP, in addition to studies such as DRX. The final compounds exhibited nematic and smectic liquid-crystalline phases, typical for calamitic structures. The photophysical properties were studied by absorption and emission spectra in solution in chloroform, and it was possible to observe intense green luminescence when irradiated with UV-Vis light. The efficiency of the photoluminescence was evaluated by relative quantum yield in solution and the electrons lifetime study allows characterizing this process as fluorescence. In addition, solvatochromism was studied, applying the Lippert-Mataga equation, in order to evaluate the influence of the polarity of the solvent on the optical properties. Studies to determine the ability to act as a fluorescent sensor were performed through the interaction of quinoxaline derivatives with different metals. The photophysical properties of these materials were also investigated in solid phase by absorption and emission spectra and absolute quantum yield. The evaluation of the influence of heating in the optical properties was verified as well as the morphology of the thin films. Theoretical calculations, through DFT, allowed the comparison of the experimental data with the theoretical values.
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7
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BRUNA OLIVEIRA DO NASCIMENTO
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PHYTOCHEMICAL STUDY AND BIOLOGICAL ACTIVITIES EVALUATION OF THE EXTRACTS AND CONSTITUENTS OF Macrolobium rigidum (R.S Cowan)
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Leader : JORGE MAURICIO DAVID
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MEMBRES DE LA BANQUE :
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JORGE MAURICIO DAVID
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SILVIO DO DESTERRO CUNHA
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ELIANE DE OLIVEIRA SILVA
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LOURINALDA LUIZA DANTAS DA SILVA SELVA DE OLIVEIRA
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CLAYTON QUEIROZ ALVES
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Data: 18 juin 2019
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Afficher le Résumé
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This work describes the first phytochemical and biological study of aerial parts of Macrolobium rigidum. The extracts obtained by partition of the crude methanolic extract of the leaves and the stem of M. rigidumwere submitted to in vitrobiological activity tests: cytotoxic against A. salina microcrustacean, evaluation of the antioxidant activity measured by the DPPH radical scavenging assay method , anticholinesterase, by the microplate method, evaluating the inhibition of the acetylcholinesterase enzyme, and antimicrobial against the bacteria S. aureus, P. aeruginosa,Salmonellaand E. coli, by means of determination of the minimum inhibitory concentration (MIC) detected with the aid of the developer resazurin. The determination of the total phenolic content by the Folin-Ciocalteu method was also performed. None of the extracts presented toxicity, in contrast to the DPPH radical, the extracts in EtOAc presented activities in concentration of 10μg.mL-1, the extracts in EtOAc and in BuOH of the stem presented minimum inhibitory concentration against Salmonellaof ≤125μg.mL-1, in comparison to P. aeruginosa, leaf extracts had lower MIC values. The contents of total phenolic compounds in extracts of M. rigidumranged from 46.438 ± 0.006 to 446.668 ± 0.018 mg EGA/ g of extract. The triterpenes friedelin and taraxerol, the steroid mixture composed of β-sitosterol, capesterol and stigmasterol, the flavonoids, among them apiginine and an unusual glycosylated coumarin, were all isolated by means of chromatographic methods, all identified by analysis of the data of 1H, 13C, HSQC and HMBC NMR spectra, IR region and UV-vis region spectra and mass spectrum.
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8
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LEILA SANTANA VIANA BARBOSA
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Evaliation of amino acids and glutathione coated CdTe quantum dots interaction to urine and dietary supplements analysis
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Leader : RODOLFO DE MELO MAGALHAES SANTANA
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MEMBRES DE LA BANQUE :
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RODOLFO DE MELO MAGALHAES SANTANA
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MARIA DAS GRACAS ANDRADE KORN
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JOSUE CARINHANHA CALDAS SANTOS
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Data: 28 juin 2019
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Afficher le Résumé
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Amino acids (AA) are the main constituents of proteins, and their deficiency or accumulation leads to health damage. Different methods were developed using quantum dots (QD), as photoluminescent probes for indirect AA determination in different matrices.These methods were based on the turn-off-turn-on strategy, which consists in quencher removal (usually metal species) from QD surface by interaction with analytes.Thereby, the present work aims to evaluate AA-QD for the direct analytical methods and its application in urine and supplements samples. Sensitization assays of glutathione-coated CdTe QD (GSH-CdTe) with different sizes were performed against 7 amino acids alone and they were divided according to the properties of their side chain. Experiments with different temperatures and ionic strength were performed to evaluate the quenching mechanism and AA-QD interaction type. Chemical parameters of the probe, such as pH (5 to 10), buffer concentration (0.1 to 0.8 mol L-1), QD size (2.2 to 3.0 nm) and concentration (2.5 to 35 μmol L-1) were evaluated to ensure greater method sensitivity. It was observed that AA with positive charge or neutral polar chains, namely L-histidine (His) and L-threonine (Thr), have reduced 90% of nanocrystal fluorescence. Reaction parameters assesment has shonw that in ammoniacal buffer (0.25 mol L-1) at pH 8.0 GSH-CdTe (2.2 nm) responded only to His, indicating specificity of luminescent probe to the analyte. Studies on the His-QD mechanism suppression and interaction indicated the occurrence of static quenching with complex association constant (ka) ranging from 2.81x10-5 to 9.7x10-6 L mol-1 from 20 °C to 35 °C. In addition, no variation of ka (Δka <11%) was observed changing ionic strength suggesting preferently His-QD interations of Van der Waals force and/or hydrogen bonding.The thermodynamic parameters of His-QD interaction were determined using the Van 'Hoff equations, obtaining values of ΔH = -160.5 kJ mol-1 K, ΔS = -0.858 J mol-1 and ΔG of -411.931 to -424.803 kJ mol-1 K (T = 20 to 35 °C). Parallelism was observed between the calibration curves in aqueous solvent and sample indicating the absence of matrix effect. Under optimal conditions the developed method presented a linear range of 2.5 to 35 mmol L-1 (R = 0.9970, n = 7). The detection limit was 1.1x10-3 mol L-1 (0.170 mg mL -1), showing good precision with RSD <2.5% (for 2.5 and 20 mmol L-1; n = 6). The accuracy method was evaluated by addition and recovery assays for two to three concentration levels in real triplicate in urine and supplement samples, presenting adequate recovery values for both samples demonstrating good accuracy.The method was applied to urine and dietary supplement samples. Histidine was not detected in urine samples. However, in supplement samples, His was determined in amounts equal to 135±5 and 417.2±0.2 mg per tablet.
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9
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ANA CAROLINE NEVES DA SILVA
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Study and application of catalysts based on lanthanum, strontium and cobalt in the catalytic combustion reaction of methane.
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Leader : SORAIA TEIXEIRA BRANDAO
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MEMBRES DE LA BANQUE :
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SORAIA TEIXEIRA BRANDAO
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LILIAN MARIA TOSTA SIMPLICIO RODRIGUES
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ROGER THOMAS FRANCOIS FRETY
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Data: 28 juin 2019
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Afficher le Résumé
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In the present work were studied perovskite catalysts La1-xSrxCoO3 (x = 0.0; 0.2; 0.4) and cobalt oxide, synthesized by the citrate method. The synthesis methodology favored the formation of nanostructured solids with crystalline phases. The obtained samples were characterized and evaluated in the methane catalytic combustion reaction aiming to analyze, mainly, the catalytic effect caused by the partial replacement of lanthanum by strontium in the perovskite site A. The catalytic properties of the catalytic systems were investigated and related to the structure. The materials were analyzed by X-ray diffraction (XRD), thermogravimetric analysis (ATG), surface area measurement by the BET method, transmission electron microscopy (TEM), diffuse reflectance visible Uv spectroscopy (Uv-vis DRS). , hydrogen reduction at programmed temperature (TPR-H2) and X-ray fluorescence (FRX). As a catalytic test, all samples were submitted to the combustion thermoprogrammed surface reaction (TPSR).The results indicate that all studied systems are active the catalytic combustion reaction of methane and the insertion of strontium in the perovskite structure favored the reduction of catalyst activation energy and ignition temperature. A relationship between reductibility of cobalt species and catalytic activity in the materials was also observed. The system that showed lower activation energy, lower ignition temperature and higher reducibility was the La0,8Sr0,2CoO3. system.
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10
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Maiara Oliveira Passos
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Effect of Isotopic Substitution on Hydrogen Abstraction Reaction Speed Constants H3COCOH + O (3P)
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Leader : TIAGO VINICIUS ALVES
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MEMBRES DE LA BANQUE :
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TIAGO VINICIUS ALVES
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MARCOS MALTA DOS SANTOS
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ORLANDO ROBERTO NETO
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Data: 4 juil. 2019
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Afficher le Résumé
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In this study, the energetic, structural, and spectroscopic parameters of the stationary points generated by the abstraction reaction O (3P) + X3COCOX → X3COCO + OX (R1 and R3) and X2COCOX + OX (R2 and R4), in which X = H or D, were obtained at DFT/BB1K/maug-cc-pVTZ, level of theory. At this level, the height of the classical barriers, V ‡, for (R1) and (R2), were 10,45 and 12,05 kcal/mol, respectively. In the aspect of chemical kinetics and dynamics, the thermal rate constants were determined using the CVT/SCT approach, in a wide temperature range (T= 250 - 2000 K). At lower temperatures, the quantum tunneling plays an important role in the k(T). At 250 K, for example, the CVT/SCT thermal rate constant (3,27x10-15 cm3molécule-1s-1) is 4.144 times greater than the CVT counterpart (7,89x10-19 cm3molécula-1s-1). For the reactions with deuterium, the total constant CVT/SCT (5,22x10-16 cm3molécula-1s-1) is 1.717 times greater than the CVT counterpart (3,04x10-19 cm3molécula-1s-1). The kinetic isotopic effect at this temperature, were KIER1/R3 TST = 12,38 e KIER1/R3 CVT/SCT = 6,26; KIER2/R4 TST = 15,23 e KIER2/R4 CVT/SCT = 4,94.
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11
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THIAGO ANASTACIO DA SILVA
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Oxi-CO2 parameter evaluation using LaNiO3 perovskites
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Leader : LILIAN MARIA TOSTA SIMPLICIO RODRIGUES
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MEMBRES DE LA BANQUE :
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CAMILA RIBEIRO DE OLIVEIRA FÉLIX
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LILIAN MARIA TOSTA SIMPLICIO RODRIGUES
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SORAIA TEIXEIRA BRANDAO
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Data: 5 juil. 2019
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Afficher le Résumé
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Carbon dioxide reforming of methane to syngas production was studied employing LaNiO3-based perovskite catalysts (LaNiO3, LaNi0,7Fe0,3O3 e La0,7Ce0,3NiO3), synthesized by the citrate route, objectifying contrast the catalytic performances based on substitutions in the perovskite structure, evaluating them in the catalytic reaction of the dry reform of methane in the presence of oxygen. The catalysts were characterized by TGA/DTG, XRD, TPR-H2, TPSR, TPO, specific surface área by the BET method, besides being tested in the reaction for 20h. It being verified that the substitution with Ce in the structure of LaNiO3 provides conversions and selectivities similar to perovskite in its reference state, but La0.7Ce0.3NiO3 is more viable than the others because presented the highest resistance to coke deactivation in the studied process, this being an effect comes from the addition of cerium which provides a greater stability to the structure. Afterwards, an analysis was performed to find the ideal temperature to conduct the reaction, verifying the effect of temperature on the activity, selectivity and resistance to deactivation by deposition of coke. The tests were performed at three different temperatures of 600 to 800°C, with increments of 100°C, and the results indicated that the catalytic system was sensitive to temperature variation, presenting the best results at 800°C, in which the occurrence of some parallel negative reactions to the process becomes disadvantaged. Finally, an analysis was made of the advantages of using Oxi-CO2 in favor of simpler reforms, such as DRM, concluding that Oxi-CO2 produces the best activity responses, selectivity and resistance to coke deposition , due to the addition of oxygen in the reaction
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12
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IGOR ARAÚJO LINS
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Theoretical Study of Hydrogen Abstraction Reactions of Methyl Formate by OH Radical
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Leader : TIAGO VINICIUS ALVES
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MEMBRES DE LA BANQUE :
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TIAGO VINICIUS ALVES
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ROBERTO RIVELINO DE MELO MORENO
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ORLANDO ROBERTO NETO
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Data: 5 juil. 2019
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Afficher le Résumé
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In this study, the structural, energetic, and spectroscopic parameters for the stationary points generated by the hydrogen abstraction reaction between methyl formate and the OH radical were obtained at the level of theory M06-2X/maug-cc-pVTZ. This approach was chosen after an energetic benchmark construction using the CCSD(T)-F12a/CBS classical barrier height and reaction energy as a reference. The values of classical barrier height (V ‡) for (R1) and (R2) were 1.27, and 2.40 kcal.mol−1, respectively. With the inclusion of the zero-point energy, these energetic parameters were 0.2, and 1.2 kcal.mol−1, respectively. The enthalpy of reaction at 0 K at this level were -19.1, and -18.5 kcal.mol−1. In the chemical kinetics and dynamics study, we applied the classical transition state theory (TST), and canonical variational theory (CVT) with small-curvature tunneling (SCT) in a wide temperature range (233 - 2500 K). The thermal rate constant obtained are in good agreement with the theoretical and experimental predictions.
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13
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JAMILLE SILVEIRA MATOS
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SYNTHESIS AND REACTIVITY OF 3-ACETYL-THIOENAMINONES
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Leader : SILVIO DO DESTERRO CUNHA
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MEMBRES DE LA BANQUE :
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SILVIO DO DESTERRO CUNHA
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ELIANE DE OLIVEIRA SILVA
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DIMAS JOSÉ DA PAZ LIMA
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Data: 29 juil. 2019
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Afficher le Résumé
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The interest in the synthesis of new bioactive molecules and the research for new methodologies according to the principles of Green Chemistry have been increased the last decades. 3-acyl-thioenaminones are densely functionalized intermediates with several reactive centers and they are important building blocks for several heterocyclic compounds, such as pyrazole, isothiazole and tetrazole. The aim of this work was to study green methodologies for synthesis of 3-acyl-thioenaminones and to investigate their reactivity to different nucleophiles and oxidant agent to develop a series of new molecules with biological activity. Two methodologies were developed for the synthesis of these compounds under solvent-free condition, low temperatures and solid support-free. The first methodology involved the reactions of enaminones with phenyl isothiocyanate under solvent-free condition at room temperature. The second methodology involved the same reaction condition under ultrasound irradiation. From the first methodology, it was possible to synthesize different 3-acyl-thioenaminones in yields of 18% and 78%. Most of reactions afforded a mixture isomeric 3-acyl-thioenaminones Z/E in the ratio 3:1. To investigate the reactivity of these compounds the 3-acyl-thioenaminones derivatives were synthesized from the mixture isomeric Z/E with hydrazine and iodine, with sodium azide only the isomer E was used. In the reaction with N2H4 80% in ethanol it was possible to obtain in one step the corresponding pyrazolone and pyrazole in 15% and 34% of yield, respectively. In the reaction with I2 and K2CO3 in acetonitrile the isothiazole was obtained in 17% of yield. In the reaction with NaN3 and Bi(NO3)3.5H2O in acetonitrile by microwave, 120°C, 150W and 5 min the tetrazole was obtained in 26% yield. The proposed methodology for the synthesis of 3-acyl-thioenaminone is according with the principles of Green Chemistry and it was developed with good yields. Among the 20 molecules synthesized in this work, nine are unpublished in the literature.
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14
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TAMIRES MARIEL MUNIZ MILHAZES
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Ruthenium(II) base Schiff complexes: preparation, characterization, and evaluation as potential P450-bioinspired systems
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Leader : LUCAS BOMFIM BOLZON
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MEMBRES DE LA BANQUE :
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LUCAS BOMFIM BOLZON
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JOICY SANTAMALVINA DOS SANTOS
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VALÉRIA PRISCILA DE BARROS
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Data: 1 août 2019
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Brazil is one of the countries with the highest agrochemicals consumption, among which stands out the simazine, an herbicide of the triazine class. Besides it being harmful to directly exposed humans, this substance is also responsible for several damages to the environment, specifically to water sources. Therefore, it is necessary to research about the oxidation of this molecule, in order to provide a better base of toxicological profile, as well as to assist in the remediation of systems that are affected by this pesticide. In living systems, the superfamily of enzymes that perform the metabolism of exogenous molecules (pesticides, dyes and drugs) are the cytochromes P450. These monoxygenases perform the biotransformation of substrates in a fast, versatile and high effective way, that the use of synthetic model-systems that mimics the catalytic function of P450 has been studied over the past three decades. In this context, the objective of this work was to synthesize, characterize and evaluate the catalytic activity of P450 in ruthenium salen complexes against oxidation of simazine. For comparative effect, compounds of iron and manganese with salen were also synthesized, [RuNOCl(Salen-N(Et)2)], [MnCl(Salen-N(Et)2)], [FeCl(Salen-N(Et)2)], [RuNOCl(Salen-MeCl)] and [MnCl(Salen-MeCl)]. These coordination compounds were characterized by spectral techniques (FTIR and UV-Vis) and electrochemical (cyclic voltammetry). The analyzes indicated the efficiency of the complexation, as well as the high-transition states of the metals that possibly act in bioinspired oxidative reaction mechanism. The catalytic assays of these complexes in the simazine oxidation were performed with the respective oxygen donors: H2O2, PhIO, NaClO and m-CPBA and the oxidation products were separated by HPLC. The catalysts obtained satisfactory results in the substrate conversion, particularly for [Ru(Salen-MeCl)]/NaClO system which achieved 26.4%. Regarding to the product distribution, the most selective catalyst was the [Ru(Salen-N(Et)2)] since in the presence of all oxidants it was reached only two products.
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15
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ALBA DE OLIVEIRA DUTRA
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SYNTHESIS OF FUNCTIONALIZED 1-AZADIENES DERIVATIVES OF ENAMINONAS VIA REACTIONS MULTICOMPONETES AND ITS EMPLOYMENT IN THE PREPARATION OF PIRAZÓIS
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Leader : SILVIO DO DESTERRO CUNHA
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MEMBRES DE LA BANQUE :
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FERNANDA ANDREIA ROSA
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MAURICIO MORAES VICTOR
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SILVIO DO DESTERRO CUNHA
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Data: 2 août 2019
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Afficher le Résumé
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1-Azadienes are of great interest in organic synthesis because of their vast versatility in synthetic applications. This study brings innovative reactions to the methodology used to obtain 1-azadienes. Such methodology involves four reagents in two steps that are added in the one-pot way to the reaction medium (multicomponent reactions), so that the products formed incorporate structural characteristics of each of the reagents. Through this methodology, seven analogous azadienes were synthesized, resulting in four new ones to the literature. Still in the pseudo tetracomponent, three tetracyclic pyrazole compounds were synthesized. Obtaining different compounds demonstratesthe influence of the different substituents (activators and disactivants) on the diazonium salts, which are determinants for the final product. The azadienes synthesized by means that methodology were submitted to reactivity tests against oxidizing and reducing agents, in order to study possible synthetic transformations. The results were nitrogenous aromatic heterocycles of five members belonging to the azole class. In addition, trisubstituted and tetrasubstituted pyrazoles were synthesized in a novel way. This class of compounds is important because they belong to a set of molecules that, in addition to high medicinal potential, have a wide range of other applications, such as: pharmacological, agricultural, materials science and photographic.
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16
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JÉSSICA FRANÇA DE OLIVEIRA
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Investigation of the electrochemical synthesis on the capacitive properties of RuO2 and RuO2-WO3 electrodes
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Leader : ADRIANE VIANA DO ROSARIO
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MEMBRES DE LA BANQUE :
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ADRIANE VIANA DO ROSARIO
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RAILDO ALVES FIUZA JUNIOR
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ERNESTO CHAVES PEREIRA DE SOUZA
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Data: 2 août 2019
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Afficher le Résumé
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Electrochemical capacitors have shown a myriad of advantages compared to conventional energy storage devices such as batteries and parallel plate capacitors. Studies have demonstrated that transition metal-based pseudocapacitors are the most promising electrochemical capacitors, as they exhibit high values of specific capacitance and extended life cycle. However, the high cost of ruthenium oxide, due to its sparse natural abundance, is its major drawback. On the other hand, tungsten oxide, whose capacitive properties have not yet been explored by the scientific literature, can feature as a pseudocapacitor component inexpensively. Understanding how the preparation variables influences the final characteristics of the oxides is crucial for the synthesis of increasingly efficient and effective materials. In this sense, factorial experimental design is a powerful tool. However, few are the studies which utilize this compelling approach in this specific field. This research intended to analyze the variables of preparation (scan rate, number of scans, and temperature of deposition) of ruthenium-tungsten mixed-oxide by cyclic voltammetry. This study was performed based on a 23factorial design using as a response factor the specific capacitance (Cs), and the maximum value obtained was of 236.5 Fg-1. The resolution of the factorial design revealed that the variables that most influence the specific capacitance values are, respectively, scan speed and number of cycles. Once the optimum conditions were found, the metal ions proportion in the electrolytic solution were studied and it was observed that the higher ruthenium oxide proportion, higher the specific capacitance values. However, electrodes prepared using a Ru/W molar ratio of 70/30 exhibited Cs values in the order of 300Fg-1, provin to be a very promising system for electrochemical capacitors applications.In the study of growth and nucleation by chronoamperometry from different electrolytic solutions the current transients indicated that the nucleation process occurs instantaneously on the substrate surface.
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17
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JAQUELINE REIS DE SOUZA BISPO
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BIOREDUCTION AND OXIDATIVE KINETIC RESOLUTION OF OXYGENATED COMPOUNDS USING THE MARINE SPONGE Cliona varians
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Leader : VALERIA BELLI RIATTO
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MEMBRES DE LA BANQUE :
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VALERIA BELLI RIATTO
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JORGE MAURICIO DAVID
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ADEMIR EVANGELISTA DO VALE
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Data: 25 sept. 2019
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Biocatalysis is an important tool in organic synthesis, especially in the synthesis of chiral molecules, due to the biological activity associated with these compounds. Brazil has a vast biological diversity, interesting from the biocatalytic point of view, which is still underused. The need to obtain chiral compounds through cleaner synthetic routes (Green Chemistry) makes important the controlled exploitation of fauna and flora, in order to develop new biocatalysts. In this work, the biocatalytic potential of the Cliona varians marine sponge was studied in stereoselective bioreduction reactions of pro-chiral ketone available in the laboratory (acetophenone, nitroacetophenone and acetylfuran) and in the oxidative kinetic resolution of racemic secondary alcohols chemically prepared [p-nitrophenylethanol, p-methoxyphenylethanol and 1-(2-furylethanol)]. To obtain racemic standards for comparison with the products obtained by the bioreductions, the ketones were reduced chemically (yields 75-97%). The reactional products were characterized by spectroscopic techniques (IV, 1H-RMN e 13C-RMN). The experiments were carried out by means of glucose and fructose as additives, and also when there were no additives. The biotransformation reactions were evaluated for 3, 5 and 7 days and analyzed through chiral CG. Hydroxylated products were obtained with moderate conversions and ee ranged from 20% to 84%, alternating the absolute R or S configuration depending on the additive employed.
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18
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TAHYANA MARA CHAGAS CARVALHO RANGEL
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Oxidation of sulindac anti-inflammatory catalyzed by metal complexes as biomimetic and bioinspired models of
cytochrome P450
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Leader : JOICY SANTAMALVINA DOS SANTOS
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MEMBRES DE LA BANQUE :
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JOICY SANTAMALVINA DOS SANTOS
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ELIANE DE OLIVEIRA SILVA
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VALÉRIA PRISCILA DE BARROS
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Data: 28 nov. 2019
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Afficher le Résumé
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Cytochrome P-450 (CYP) enzymes are present in all living organisms and participate of phase I metabolism of drugs, pollutants and other xenobiotics. A more practical, economical and ethical way to study these enzymes metabolites can be done through the use of biomimetic and bioinspired catalysts, structurally similar to CYP enzymes, instead of in vitro / in vivo methods. In this work we studied the sulindac drug oxidation (a non-steroidal anti-inflammatory used for the treatment of rheumatoid arthritis) using biomimetic and bioinspired catalysts: metalloporphyrins, metallosalens (Jacobsen isomers) and cyclam (tetraazocycletretradecane) with iron centers. (III) and manganese (III). Iodosilbenzene, hydrogen peroxide, meta-chloroperbenzoic acid and sodium hypochlorite were used as oxygen donors for the reactions. All reactions were analyzed by high performance liquid chromatography (HPLC). The catalysts used in this study were efficient in sulindac oxidation and better yields (38.2%) was achieved by the system using FeCyclam with NaClO at 1:40:400 molar ratio, followed by FeTFPP and NaClO system at the same molar ratio (31.1%). Good system conversions were observed using Cyclam and NaClO catalysts as oxidant. The results of catalytic studies mediated by biomimetic / bioinspired systems were compared to those obtained by sulindac biotransformation using the fungus Cunninghamella elegans. Oxidation products obtained by biotransformation were separated by classical column chromatography and analyzed by 1H and 13C NMR, and compared to results obtained by biomimetic catalysis. It was possible to separate only one of the biotransformation products, named P7 herein, and identified as 2-(5- fluoro -1(hydroxy-(4-(methylsulfinyl)phenyl)methyl)-2-methyl-1H-inden-3-yl)acetic acid. This compound was also confirmed as a sulindac oxidation product for biomimetic reactions using Fe/ MnCyclam and NaClO.
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19
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ADALBERTO SANTANA LIMA JUNIOR
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Low-lying electronic states of SiF+ specie
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Leader : TIAGO VINICIUS ALVES
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MEMBRES DE LA BANQUE :
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TIAGO VINICIUS ALVES
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ROBERTO RIVELINO DE MELO MORENO
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CLAUDIO HANASHIRO BARBOSA SILVA
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ANTONIO GUSTAVO SAMPAIO DE OLIVEIRA FILHO
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Data: 29 nov. 2019
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In this study, the structural, energetic and spectroscopic parameters of the low-lying electronic states (Λ + S) of the SiF+, correlating with the two lowest dissociation channels [Si+(2Pu) + F(2Pu) e Si+(4Pg) + F(2Pu)], were obtained at MRCI+Q/aug-cc-pV5Z theory level. At this level, the energy difference between these dissociation channels (41145 cm-1), corresponding to excitation Si+(2Pu) - Si+(4Pg). Of the twelve states that correlate with the first dissociation channel, eight of them are stable, (X 1Σ+, 1 3Π, 1 3Σ+, 1 3Δ, 1 1Δ, 1 1Σ-, 1 3Σ+, 2 1Σ+), while for the second channel, only five states were show to be energetically stable, (3 3Π, 1 5Π, 2 3Σ+, 4 3Π, 3 3Σ+). For the ground electronic state (X 1Σ+), the internuclear distance (Re) and vibrational frequency (𝜔e), at MRCI+Q/aug-cc -pV5Z, were 2,891 a0 and 1,043 cm-1, respectively. For the first excited state, (1 3Π), these values were 2,929 a0 and 981 cm-1, respectively. The values obtained in this study are in excellent agreement with previous theoretical and experimental studies. Based on the accurate description of these states, this work provides the structural, energetic and spectroscopic parameters for the first time in the literature, for the electronic states correlated with the second dissociation channel.
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20
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NATHALIA EVELYN MORAIS COSTA
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Synthesis of 2-AMINO-1,4-Naphthoquinone-derived Penta-Heterocycles Through Formal [3 + 2] and [3 + 2 + 1] Promoted Azoric Acids
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Leader : SILVIO DO DESTERRO CUNHA
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MEMBRES DE LA BANQUE :
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SILVIO DO DESTERRO CUNHA
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ANDRE ALEXANDRE VIEIRA
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FERNANDO DE CARVALHO DA SILVA
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Data: 12 déc. 2019
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Afficher le Résumé
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Nitrogenous heterocycles are substances of great importance their biological properties and also for being present in highly consumed substances worldwide. As regarding to this, a great deal of effort has been placed on the synthesis of new compounds, mainly nitrogenous multicycles, once that these products have complex nuclei, with different chemical and biological functions. In this work, was synthesized nitrogen heterocycles from formal azaannulation reactions [3 + 2] and [3 + 2 + 1] that constitute an efficient and versatile protocol for the formation of multiple bonds with step reduction, and production of by-products, making this synthetic route an alternative incorporated into Green Chemistry. An important building block os nitrogen heterocyclic is enaminones, which this work were limited to the 2-amino-1,4-naphhoquinones type. Enaminones are densely functionalized and that are easily obtainable, and have dual reactivity which can act as electrophile or nucleophile, a characteristic that makes it interesting from a synthetic point of view. In this work, the employed enaminones act as nucleophiles and its reactivity was tested against aromatic aldehydes and ninhydrin leading to linear pentacycles, isocoumarins and dihidroxylated pyrols. In order to optimize the synthesis of aza-pentacenotetraones from 2amino-1,4-naphthoquinone and aromatic aldehydes, a study of reactions promoted by organic diacids, and a solvent study was carried out. Fourteen products were isolated with yields between 32 and 97%, among them eight unpublished. N-substituted 2-amino-1,4-naphthoquinones reactivity to ninhydrin is also investigated. In this case, it was possible to isolate two distinct nuclei: isocoumarins and dihydroxylated pyrrols, both in a microwave reactor. Studying the synthesis of isocoumarins made, it was possible to isolate them in yields between 45 and 99%, even with a small amount of catalyst. Also, it was possible to isolate 10 products, among them four unpublished. Dihydroxylated pyrroles were isolated with yields between 30% and quantitative, without catalyst. Eleven products were isolated which all are unpublished. On the reactivity of 2-amino-1,4-naphthoquinones it was possible to show a reactivity sensitive to the reaction medium. In addition, all isolated nuclei exhibit therapeutic potential described in the literature.
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21
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FERNANDO ALVES BARRETTO
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Synthesis of coumarins, benzofurans, itaconimides, and coumarin-itaconimide hybrids using the Wittig reaction of phosphorus ilids derived from maleic anhydride
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Leader : SILVIO DO DESTERRO CUNHA
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MEMBRES DE LA BANQUE :
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SILVIO DO DESTERRO CUNHA
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ELIANE DE OLIVEIRA SILVA
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CECILIA MARIA ALVES DE OLIVERA
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Data: 16 déc. 2019
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Afficher le Résumé
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The main purpose of this scientific research is to evaluate the reactivity of α- triphenylphosphoranylidene-succinic anhydride and triphenylphosphoranylidene-pyrrolidine against dicarbonic electrophiles to obtain coumarins, benzofurans, itaconimides and coumarin-itaconimide hybrids. Using Wittig reaction, with phosphorus ilide (83) and furfuraldehyde (74), was possible verify formation of alkene (76), which cannot be isolated due to its instability. Thereby, the mixture of (76) and triphenylphosphine oxide was submitted in condition of acetic anhydride and sodium acetate for 15 hours at room temperature. After this period, the reaction medium was subjected to reaction in the microwave reactor under the following conditions: 16 min, 100 °C, 200W, 250psi, obtaining benzofuran (77a) in 95% yield for two steps. Basic hydrolysis of (77a) drove benzofurans (77b) and (78). Aryl itaconimide and coumarins can be obtained from three-component synthesis at room temperature, and MeOH employing N- arylmaleimides (86a-e), salicylaldehydes (88) and triphenylphosphine. In this research, it was possible accessed a series of E-itaconimides and coumarins (89a-i), with 28-89% yields. When was employed the coumarins 112(a, b) in phosphorus ilides 87(ba-dc) in EtOH and reflux for a period of 15-22 hours, coumarin-itaconimide hybrids 113(a) and 114(a,c) were obtained. The compound (113a) was obtained in 62% yield and compounds 114(a-c) in 10- 18% yield. Therefore, a new synthetic methodology for obtaining benzofurans compounds was developed by Wittig reaction. New coumarins-itaconimide hybrids and coumarins were obtained using the threecomponent synthesis of maleimides, salicylaldehyde and triphenylphosphine derivatives by in situ Wittig reaction.
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22
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JOSE ROGERIO SOUZA DA SILVA
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OPTIMIZATION OF METHODOLOGY FOR DETERMINATION OF INORGANIC CONSTITUENTS IN QUAIL EGGS USING ICP OES
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Leader : RENNAN GEOVANNY OLIVEIRA ARAUJO
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MEMBRES DE LA BANQUE :
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ANIBAL DE FREITAS SANTOS JUNIOR
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DANIELE CRISTINA MUNIZ BATISTA DOS SANTOS
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RENNAN GEOVANNY OLIVEIRA ARAUJO
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RODOLFO DE MELO MAGALHAES SANTANA
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Data: 19 déc. 2019
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In the present work, an analytical method was optimized for the determination of inorganic constituents in quail eggs using the optical emission spectrometry with inductively coupled plasma (ICP OES). To optimize the conditions of the sample preparation and operational procedures of the spectrometer, three-level experimental planning was applied, based on the Box Benhken and Doehlert models, respectively. The sample preparation was established using diluted nitric acid, being suitable for conception of Green Chemistry. The proposed analytical method proved to be sensitive for the determinations of Ba, Ca, Cu, Fe, K, Mg, Na, P, S, Sr and Zn in quail eggs. The limits of quantification (LoQ) obtained varied between 7 ng g-1 (Ba) and 28 µg g-1 (S). Accuracy of the analytical method was confirmed through the analysis of certified reference materials of bovine muscle (NIST 8414) and egg powder (NIST 8415), obtaining agreement values between 81.60 ± 0.10% and 97.50 ± 0 , 01% for NIST 8414 and 80.0 ± 0.3% and 108.1 ± 0.04% for NIST 8415 respectively. Precision was expressed as relative standard deviation (RSD), being less than 9% (Ca, n = 3). The proposed methodology was applied to the analysis of 30 samples of quail eggs. For macroelements concentrations (Ca, K, P, Mg, Na and S) found varying between 319 ± 9 µg g-1 (Mg) and 8643 ± 218 µg g-1 (P). The microelements and trace elements, Ba, Cu, Fe, Sr and Zn, had their concentrations varying between 4.21 ± 0.26 µg g-1 (Sr) and 65.5 ± 9.7 µg g-1 (Fe) . Multivariate data analysis was applied in order to characterize the quail egg samples in terms of their chemical composition, where it was observed that they did not present a separation into different groups according to the elementary compositions. However, compared to chicken eggs, quail eggs showed higher concentrations for Ca, K, Na, P, S and Zn, representing up to 23% of the recommended digestion index (IDR), established for calcium.
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23
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TALITA MARIA SILVA DE SOUSA
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SYNTHESIS STUDY OF PEROVSKITA LaNiO3 TYPE CATALYTIC PRECURSORS SUPPORTED IN SiO2 APPLIED IN DRY REFORMING OF METHANE
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Leader : SORAIA TEIXEIRA BRANDAO
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MEMBRES DE LA BANQUE :
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SORAIA TEIXEIRA BRANDAO
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ROBERT NEWTON DA SILVA HENRIQUES MAGALHÃES
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ANDRE ROSA MARTINS
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Data: 20 déc. 2019
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Unsupported and SiO2 supported Perovskite catalytic precursors were prepared by the citrate method, wet impregnation and as a proposal of this work, single step synthesis with addition of the support in the citrate route. Subsequently, they were characterized by TG, FTIR, XRD, BET, BJH, SEM, MET, TPR-H2 and evaluated in dry reform of methane. XRD results indicated that the citrate route was satisfactory to obtain the desired perovskite phase and the diffractograms of the reduced samples showed the Ni/La2O3 catalyst formation, and for the supported Ni/La2O3/SiO2 samples. It was verified by the average size of the crystallite that the support promoted the reduction of the metallic phase. Scanning and transmission electron microscopy and surface area and porosity results indicated that the difference in synthesis between the supported materials generated different distributions of the precursors in the support as well as different particle sizes. The results of TPR –H2 showed the significant effect of the synthesis method and the presence of the support under Ni reduction. All catalysts studied were active for methane dry reforming with reaction temperatures below the homogeneous phase. The effect of the support on reducing the activation energy of the reagents, with reaction temperatures lower than the unsupported sample, was also highlighted. The singlestage synthesized sample showed the best results for reagent conversion and product yields, in addition to the near-stoichiometric H2/CO ratio. In addition, the TPO results also indicated the efficiency of this catalyst, due to the 50 times lower carbon formation compared to the reference sample, suggesting that the synthesis method proposed by this work made it possible to obtain a material with high homogeneity and with particle size and surface area, suitable for catalytic activity.
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Thèses |
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1
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GECIANE ALVES DOS SANTOS
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EFFECT OF MAGNESIUM AND IRIDIDE ON PROPERTIES OF NICKEL AND COBALT CATALYSTS OBTAINED FROM FROM PEROVSKITA
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Leader : MARIA DO CARMO RANGEL SANTOS VARELA
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MEMBRES DE LA BANQUE :
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ANDRE ROSA MARTINS
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CESÁRIO FRANCISCO DAS VIRGENS
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HUMBERVÂNIA REIS GONÇALVES DA SILVA
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LUIZ ANTONIO MAGALHAES PONTES
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MARIA DO CARMO RANGEL SANTOS VARELA
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Data: 21 janv. 2019
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Afficher le Résumé
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The limitation and dependence of energy sources are stimulating environmental awareness, thus promoting the search for alternatives to energy from renewable and sustainable sources, such as wind energy and solar energy. In addition, there is growing interest in the production of biofuels from biomass, such as bioethanol, as an attractive source for the production of biohydrogen, which can be used both as a fuel and in internal combustion engines. The construction of the energy vector depends on factors such as the production method and the use of catalysts. The main catalysts are based on nickel, cobalt, copper, platinum, copper oxide, aluminum oxide, aluminum oxide, nickel oxide and nickel oxide. However, the study of the properties of the catalysts is necessary, since the use of catalysts influences the production of plants and nutrients of hydrogen and carbon dioxide (reform products). In this work, the effect of magnesium and iridium on the properties of nickel and cobalt catalysts supported on lanthanum oxide from perovskites, as prepared by the Pechi method, was analyzed. On the other hand, the catalysts were prepared by reducing the concentrations of hydrogen peroxide (1% w/w). After impregnation, the catalysts were reduced and then passivated. Thus, nickel, cobalt and / or iridium catalysts supported on lanthanum oxide (containing magnesium oxide or not) were added. The membranes were characterized by thermogravimetry, Fourier transform infrared spectroscopy, X-ray diffraction, surface measurement, programmed temperature reduction, ammonia desorption and programmed temperature and catalytic evaluation. All catalysts were active and selective in the steam reforming of ethanol. The addition of magnesium contributed to higher yield values for the catalyst containing lanthanum and nickel. While the catalyst contains the largest mole fraction values for products such as hydrogen and carbon dioxide. The addition of iridium positively influenced the stability of the catalysts; In addition, it led to higher values of yield and selectivity
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2
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CARLOS ALBERTO GOMES DE SOUZA
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REMOVAL OF PHENOL IN AQUEOUS EFFLUENTS ON IRON OXIDE CATALYSTS SUPPORTED IN ACTIVATED CHARCOAL
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Leader : MARIA DO CARMO RANGEL SANTOS VARELA
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MEMBRES DE LA BANQUE :
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ALEXILDA OLIVEIRA DE SOUZA
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HUMBERVÂNIA REIS GONÇALVES DA SILVA
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MARIA DO CARMO RANGEL SANTOS VARELA
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MARLUCE OLIVEIRA DA GUARDA SOUZA
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SERGIO TELLES DE OLIVA
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SORAIA TEIXEIRA BRANDAO
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Data: 23 janv. 2019
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Afficher le Résumé
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Advanced Oxidative Processes (AOPs), where hydrogen peroxide is combined with a heterogeneous catalyst, have been established as one of the most promising alternatives for the removal of organic pollutants from aqueous effluents, especially phenols. Among the AOPs, Fenton reaction has been pointed out as one of the most efficient ones. Aiming to develop catalysts more efficient than those describe in literature, as well as to decrease the industrial and agriculture wastes in the environment, catalysts based on iron oxide supported on activated carbons obtained from lignocellulosic and of polymeric materials, to the removal of phenols from aqueous streams, through by oxidation with hydrogen peroxide. Activated carbons were prepared by carbonization/activation of flamboyant pods (agricultural wastes) and Amberlyst-15 polymeric resin (industrial waste), using steam, magnesium chloride, iron nitrate as activators, followed by functionalization with sulfuric acid and nitric acid and impregnated with iron nitrate solutions. Samples were characterized by thermogravimetry, Fourier transform infrared spectroscopy, Raman spectroscopy, X- ray diffraction, specific surface area and porosity measurements, apparent density measurements and scanning electron microscopy. The obtained samples were evaluated in phenol removal by Fenton reaction at room temperature. It was observed that the two precursors were suitable for the production of activated carbons. For all cases, activation led to a significant increase of specific surface area, except for activated carbon obtained with iron nitrate from the polymer resin. The physical activation favored the formation of pores in the activated carbon, while the acid functionalization promoted a significant destruction of pores and, consequently, a decrease of the specific surface area. The incorporation of iron in the supports led to the production of catalysts based on iron oxides (magnetite and hematite) supported on activated carbons. The catalysts activated with magnesium chloride, iron nitrate and steam were able to remove phenol by Fenton reaction; most of them were more active in the reaction, showing low adsorptive capacity. On the other hand, the iron oxide catalyst obtained through pod and activated with steam was the most efficient for phenol removal, being the most promising to degrade organic compounds in industrial effluents, decreasing environmental problems.
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3
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Alessandra Tanajura Campos
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DEVELOPMENT AND VALIDATION OF A METHOD FOR PREDICTING SULFUR CONTENT IN DIESEL BIODIESEL MIXTURES BY SPECTROFLUORIMETRY AND MULTIVARIATE CALIBRATION WITH ROBUSTNESS IN OXIDATIVE FUEL DECAY
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Leader : CRISTINA MARIA ASSIS LOPES TAVARES DA MATA HERMIDA QUINTELLA
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MEMBRES DE LA BANQUE :
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CRISTINA MARIA ASSIS LOPES TAVARES DA MATA HERMIDA QUINTELLA
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JOICY SANTAMALVINA DOS SANTOS
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ELIAS RAMOS DE SOUZA
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IDALIA HELENA SANTOS ESTEVAM
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WAGNA PILER CARVALHO DOS SANTOS
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Data: 24 janv. 2019
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Afficher le Résumé
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The use of sustainable fuels has a high value in the current global energy configuration. However, the presence of sulfur in diesel is a point that has a great environmental concern, because high concentrations of the element, can cause several damages. The present work had the objective of developing and validating a method to predict sulfur content in biodiesel-diesel blends, usingspectrofluorimetry and partial minimum squares methods. Before starting the work, a review of prior, significant literature was carried out in order to identify studies related to the topic, facilitate theory development as well as "technological bottlenecks". The methodology for determining the sulfur content consisted of the preparation of biodiesel blends in diesel and biodiesel oxidized in diesel with different sulfur contents, which cover the limits set by the National Petroleum Agency and in the characterization of the samples by infrared spectroscopy and. Subsequently, the multivariate calibration curves were constructed as a function of the sulfur concentration and using its Sulfur in Di-n-Butyl Sulfide standard through the data obtained in the x-ray fluorescence and fluorescence induced by light emitting diode. The same samples were used to perform the correlation of the reference method (Xray fluorescence), consistent with the standard ABNT NBR 14533, and the new method proposed using the equipment Quimisspectrofluorimeter Q798FIL. The multivariate calibration models obtained low deviations, being around 0.33845 and 1.5045 for B10 and B20, in this order, with addition of sulfur standard obtained in the reference equipment, and for the proposed method was 0.9791 for B10 and 0.6046 for B20. On the other hand, with addition of elemental sulfur, mean standard deviation of 0.3771 and 2.727 (X-ray fluorescence) and 0.3644 and 0.9587 (light emitting diode induced fluorescence) were obtained for B10 and B20, respectively. The addition of elemental sulfur provided a suitable correlation for B10 (R2 of 0.9633) and for B20 (R2 of 0.9745) as well as the addition of its standard for B10 (R2 of 0.9903) and for B20 (R2 of 0.9590). According to the t and F hypothesis tests it was concluded that the proposed method (fluorescence induced by light-emitting diode) meets the proposed objective, presenting also further advantages such as cost, speed of analysis and simplicity.
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4
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Maria Antonieta Pereira de Almeida Santiago
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DEVELOPMENT AND APPLICATION OF ANALYTICAL METHOD MULTI-RESIDUE BY LPME/GC-MS FOR THE DETERMINATION OF PESTICIDES IN RED WINE SAMPLES
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Leader : ANDRE ALEXANDRE VIEIRA
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MEMBRES DE LA BANQUE :
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HAROLDO SILVEIRA DOREA
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GISELE OLIMPIO DA ROCHA
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JAILSON BITTENCOURT DE ANDRADE
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LILIAN LEFOL NANI GUARIEIRO
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WILSON ARAUJO LOPES
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Data: 5 févr. 2019
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The conventional cultivation of grapes for wine production is characterized by the use of a number of different pesticide groups, in which the group that finds the greatest application are the fungicides. Some classes of pesticides are resistant to the fermentation process, which results in their presence in the final product, affecting wine quality and consumer health. The routine methods used in the analysis of pesticide residues generally require a large amount of time and of organic solvents due to the steps involved in preparing the sample prior to the chromatographic analysis. The aim of the present study was to present the steps involved on the development a simple, efficient and low solvent consumption method for the determination of 17 pesticides of different classes (including organophosphorus pesticides, organochlorine, pyrethroid and acaricide) in red and rosé wine, using liquid phase microextraction with a binary solvent mixture (BS-LPME). Extraction parameters, including type and volume of the extraction solvent, salinity, stirring time, extraction time and volume of wine were tested. Once the final extraction conditions were established, the procedure was evaluated in terms of its merit figures: selectivity, linearity, precision, accuracy, limits of detection and quantification. The correlation coefficients between 0.9987 and 0.9999 were obtained by means of matrix equalization using the analytical curves, indicating a good linearity for the working conditions. The limits of detection and quantification ranged from 0.044 to 0.233 μg L-1 and 0.294 to 0.777 μg L-1, respectively. The analytical method was applied to 14 red and rosé wine samples from different origins. The presence of the demeton-o, methylparathion, malathion, dursban and azoxystribin pesticides was found in concentrations ranging from levels below the detection limit up to 24.8 μg L-1 (dursban). The results showed that the method proved to be efficient for the simultaneous identification and quantification of 17 pesticides. Its advantages are the simplicity and the possibility of application in colored and/or turbid samples.
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5
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VANESSA DE SOUZA SANTOS
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EVALUATION OF THE DISTRIBUTION OF ESSENTIAL AND POTENTIALLY TOXIC ELEMENTS IN SAMPLES OF GRAPE MUST AND SOIL OF THE REGION OF THE SÃO FRANCISCO SUBMEDIO.
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Leader : MARIA DAS GRACAS ANDRADE KORN
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MEMBRES DE LA BANQUE :
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KARINA SANTOS GARCIA
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MARCOS DE ALMEIDA BEZERRA
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MARIA DAS GRACAS ANDRADE KORN
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MARIA ELISABETE MACHADO
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RODOLFO DE MELO MAGALHAES SANTANA
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Data: 8 févr. 2019
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The city of Petrolina/PE, located in the Submédio São Francisco produces grapes year-round, destined for both the domestic and international markets. However, content information of essential and potentially toxic elements in grape must in this local is limited. The objective of the present work was to evaluate the distribution of essential and potentially toxic elements in samples of grape must (Al, As, Ca, Cu, Fe, K, Mg, Mn, Se and Zn) and in vineyard soil (Co, Cu, Fe, Mn, Ni, V, Pb and Zn) using inductively coupled plasma optical emission spectrometry (ICP OES), in order to establish a profile of the different types of grapes produced in Petrolina / PE. The decomposition with diluted acid assisted by microwave was proposed for grape must and were analyzed seven grape varieties (Italy Moscato, Italy Melhorada, Arra-15, Scarlotta, Crimson, Benitaka and BRS Isis). The decomposition procedure for grape must had low reagent consumption (1 mL of HNO3 and 1 mL of H2O2), low dissolved organic carbon (<2% m v-1) and low residual acidity (0.8 mol L-1) compared to others procedures described in the literature. The method was validated with good precision (RSD <7%), low LOQ (0.03 to 2.7 mg L-1) and the accuracy of the method was verified through addition and recovery tests, with recovery variation of the elements of 81 ± 0.1 to 119 ± 0.8%. The concentration ranges, in mg L-1, for the analytes in the samples of grape must were: Al (0.8 ± 0.2 - 8.4 ± 0.6), As (0.30 ± 0.03 - 0.51 ± 0.08), Ca (45.9 ± 0.7 - 115, 6 ± 3,3), Cu (0.06 ± 0.01 - 3.03 ± 0.05), Fe (0.50 ± 0.04 - 6.1 ± 0.1), K (718 ± 48 - 1833 ± 4) Mn (0.06 ± 0.01 - 0.33 ± 0.04), Mg (35.5 ± 7.8 - 122.4 ± 0.8), Mn (0.6 ± 0.01 - 0.33 ± 0.04), Se (0.6 ± 0.1 - 1.02 ± 0.28) and Zn (0.10 ± 0.04 - 0.90 ± 0.02). There was no significant difference between the concentrations of the elements of the grape must samples and the values of the Brazilian food composition table (TACO), applying t test, at the 95% confidence level. Samples of Scarlotta and Arra-15 grape must showed higher concentrations of As than LMT by the MERCOSUR technical regulation and Se levels above the ANVISA LMT. Soil samples from grapevine cultivation were analyzed after application of the decomposition procedure of the Environmental Protection Agency, EPA 3051a. The method was validated through accuracy with analysis of certified reference material (NIST 2709a), recovery of elements (80 ± 0.5 to 119 ± 1.3%), precision (RSD <9%) and LOQ (0.4 to 3.8 µg g-1). The concentration ranges, in µg g-1, for the analytes in the soil samples were: Co (0.9 ± 0.2 - 30.1 ± 4.9), Cu (2.2 ± 0.6 - 69.4 ± 0. 9), Fe (2755 ± 30 - 18122 ± 90), Mn (50.8 ± 6.3 - 650 ± 90), Ni (2.7 ± 0.5 - 65.3 ± 3.9), V (6.4 ± 0.6 - 36.9 ± 1.5 ), Pb (3.2 ± 0.1 - 20.7 ± 2.7) and Zn (14.5 ± 2.5 - 154.3 ± 4.8). None soil sample exceeded the stipulated value for intervention in agricultural soils based on resolution 420/2009 of CONAMA. By constructing a regional geochemical basis, calculation the enrichment factor and the geoacumulation index in the soil samples, it was possible to verify that some points investigated presented significant enrichment and moderate to strong contamination for Ni and Cu contents. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied in the results in order to evaluate the main influences of the variables in the grape must and soil samples and allowed to establish a preliminary profile for each variety of grapes and differentiate the soil sample per farm. In addition, the results obtained in this work contribute to the table of mineral composition of foods, since they bring unpublished information of essential and potentially toxic elements in must sample of seven grape varieties grown in the Submédio São Francisco.
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6
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LETICIA DE ALENCAR PEREIRA RODRIGUES
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DETERMINATION OF TRANS FATTY ACIDS BY GAS CHROMATOGRAPHY IN EDIBLE VEGETABLE OILS AFTER HEATING IN THE PRESENCE OF METAL IONS
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Leader : LEONARDO SENA GOMES TEIXEIRA
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MEMBRES DE LA BANQUE :
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LEONARDO SENA GOMES TEIXEIRA
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JORGE MAURICIO DAVID
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ADRIANA COSTA FERREIRA
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WILSON ARAUJO LOPES
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HILDA COSTA DOS SANTOS TALMA
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Data: 14 févr. 2019
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Frying is one of the most widely used cooking methods in the world and has been reported as a process that increases the production of trans fatty acids (TFA). The formation of TFA occurs through the cis-trans isomerization process of the unsaturated fat, which can be favored in the presence of metallic ions and at temperatures above 180°C. The objective of this work was to evaluate the formation of trans fatty acids in samples of soybean and canola oils at typical heating temperature (180 ± 5)°C in the presence of copper and iron ions over 24 h of heating. To quantify the trans fatty acids in the oil before and after heating, the alkaline transesterification was optimized, followed by the validation of the method using gas chromatographic analysis with flame ionization detector (GC-FID). The optimization of the transesterification was performed in a univariate manner and, under the recommended conditions, the following factors were used: concentration of KOH methanolic solution at 2,0 mol L-1 , stirring time of 40 s, volume of the saturated solution of 3,0 mL NaCl and n-heptane solvent. In the validation of the chromatographic method the limits of detection and quantification, linearity, precision and accuracy were evaluated. The Cu and Fe contents were quantified in the oils before heating, and values compatible with the literature were found, revealing the contamination of origin. For the soybean oil it was observed that in the heating experiments without addition of metals there was formation in g/100g of C18:1, 9t; C18:2, 9c 12t; C18:2, 9t 12c and C18:3 trans in 24 h of, respectively: 0,10±0,02; 0,38±0,02; 0,36±0,02 and 0,92±0,01. For canola oil the formation in g/100g of C18:1, 9t; C18:2, 9c 12t; C18:2, 9t 12c and C18:3 trans was, respectively: 0,31±0,04; 0,23±0,02; 0,24±0,02 and 1,25±0,02. In the study of the influence of the metals Cu and Fe in the concentration of 10, 30 and 50 μg kg1 of oil, in general, the addition of the metal ions in the samples caused an increase in the concentrations of the trans fatty acids. In terms of the catalytic effect, iron was the metal that proved to be more efficient in promoting an increase in the concentrations in relation to copper, and, in general, these effects were higher in the concentration of 50 μg kg-1 . The results of the present work are of great importance for the society in general as it addresses the problems related to the formation of TFA in oils when submitted to heating. Copper and iron metals may be present in utensils and containers and generate increased TFA formation during heating.
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7
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LAÍS ARAÚJO SOUZA
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Evaluation of in vitro bioaccessibility of essential elements in food samples: comparison of static and dynamic methods
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Leader : MARIA DAS GRACAS ANDRADE KORN
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MEMBRES DE LA BANQUE :
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MADSON DE GODOI PEREIRA
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MANUEL MIRÓ
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MARIA DAS GRACAS ANDRADE KORN
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RENNAN GEOVANNY OLIVEIRA ARAUJO
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VALFREDO AZEVEDO LEMOS
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WAGNA PILER CARVALHO DOS SANTOS
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Data: 27 mars 2019
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Afficher le Résumé
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Given the importance of knowing the nutritional value of linseed and sesame, the main objective of this study was to compare the different in vitro methods SBET (Simple Bioaccessibility Extraction Test), UBM (Unified Bioaccessibility Method) and Versantvoort and to develop an automatic flow-through dynamic extraction system is proposed for in-vitro exploration, with high temporal resolution, of the transit of the chyme from the gastric to the duodenal compartments using the Versantvoort’s fed-state physiologically relevant extraction method., to evaluate the bioaccessibility of micronutrients. Among the in vitro methods investigated, UBM was selected and The highest bioaccessible fractions, in %, in gastric phase were observed for Mn (19–27%) and Zn (16–25%). In addition, it was found through the application of in vitro simulated gastrointestinal digestion that only a minor fraction of total Fe and Cu was potentially bioaccessible in this samples. The flow manifold was coupled on-line to an inductively coupled plasma optical emission spectrometer for real-time elucidation of the bioaccessible elemental fraction of micronutrients (Cu, Fe and Mn) in food commodities across the gastrointestinal tract. The simulated intestinal and bile biofluid (added to the gastric phase) was successively pumped at 1.0 mL min-1 through a large-bore column (maintained at 37.0 ± 2.0 °C), initially loaded with about 250 mg of linseed, using a Polyvinylidene fluoride (PVDF) filter membrane (5.0 µm pore size) for retaining of the particulate matter and in-line filtration of the extracts. The lack of bias (trueness) of the on-line gastrointestinal extraction method coupled to ICP OES was confirmed using mass balance validation following microwave assisted digestion of the residual (non-bioaccessible) elemental fraction. Mass balance validation yielded absolute recoveries spanning from 79 to 121% for the overall analytes and samples. On-line dynamic extraction was critically appraised against batch counterparts for both gastric and gastrointestinal compartments. The bioaccessibility of the chime, in the dynamic extraction, ranged from 21-30% (Cu), 6-7% (Fe) and 21-22% (Mn), already in batch extraction ranged from 42-58% (Cu), 17-52% (Fe) and 24-37% (Mn). Due to the lack of consensus in the literature regarding the agitation method in batch oral bioaccessibility testing, several extraction approaches (viz., magnetic stirring, end-over-end rotation and orbital shaking) were evaluated. While orbital shaking and end-over-end rotation approaches the gastric bioaccessibility of Fe <17 mg kg-1, magnetic stirring provided higher bioaccessibility, 31.9 ± 0.4 mg kg-1. To the best of our knowledge, this is the firt thesis reporting a fully automatic dynamic GI extraction method.
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8
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VALDINEI SANTOS DE SOUZA
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DETERMINATION OF METAL SPECIES IN SAMPLES OF INTEREST OF THE OIL INDUSTRY USING MICELARIAN SYSTEMS AND ATOMIC ABSORPTION ATOMIZATION SPECTROMETRY
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Leader : LEONARDO SENA GOMES TEIXEIRA
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MEMBRES DE LA BANQUE :
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ERIK GALVÃO PARANHOS DA SILVA
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ICARO THIAGO ANDRADE MOREIRA
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LEONARDO SENA GOMES TEIXEIRA
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MARCOS DE ALMEIDA BEZERRA
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MARIA DAS GRACAS ANDRADE KORN
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WALTER NEI LOPES DOS SANTOS
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Data: 28 mars 2019
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In this work, analytical strategies were developed for the determination of metallic species in samples of interest of the oil and gas sector using cloud point extraction (CPE) or emulsion-induced extraction (EIEB) as sample preparation procedures and spectrometric analysis of atomic absorption with graphite furnace (GF AAS). In the first stage of the work, a patent mapping was carried out in order to evaluate the current scenario and the technological and scientific maturity associated to the determination of vanadium and other species in oil and its derivatives. This search showed that there is a low technological production using vanadium as an element of research, which is a propitious field for the development of scientific and technological research with high potential for innovation. In the second stage, chemometric techniques with multivariate approaches were applied in the optimization of a method of extraction at the cloud point for the determination of vanadium in groundwater collection of tubular wells at fuel stations and surface waters of dams. The method was successfully applied and concentrations in the range of < LOQ to 2.0 μg L-1 were found for the samples collected at fuel stations and from 1.28 to 11.56 μg L-1 for surface water. The limits of detection (LOD) and quantification (LOQ) were 0.13 and 0.42 μg L-1, respectively, and analyte addition and recovery tests presented results between 84 and 122%. The third step involved the determination of vanadium, copper, and nickel in gasoline type C samples using the EIEB. Concentrations in the range of < LOQ to 15.8 μg L-1, 8.9 to 31.9 μg L-1 and < LOQ to 9.8 μg L-1 were found for V, Cu, and Ni, respectively. LOD was estimated at 2.0, 0.6, 0.7 μg L-1 while LOQ were 7.0, 2.0 and 2.3 for V, Cu, and Ni, respectively. The recoveries were between 82 and 130% for all metals. A new strategy was adopted for the determination with speciation of the volatile and non-volatile fractions of Ni and V in the common gasoline. The EIEB procedure was optimized to allow the determination of the analytes in GF AAS. The furnace conditions were also studied and temperatures of 300 and 200 °C were used in the pyrolysis step in the presence of Pd(NO3)2 modifier for the determination of the total contents of V and Ni, respectively. The thermostable fractions were determined without the use of modifier at higher pyrolysis temperatures: 1700 and 1500 °C for V and Ni, respectively. For the vanadium, the LODs, precision (% RSD, n = 8, 10 μg L-1) and recovery values were 1.1 and 0.42 μg L -1, 5.8 and 3.4% and 96-108 and 100-108% for the total content and nonvolatile fraction, respectively. For the nickel, the LODs, precision (% RSD, n = 8, 10 μg L-1) and recovery values were 3.5 and 1.7 μg L-1, 9.6 and 2.0% and 86-101 and 91109% for the total content and non-volatile fraction, respectively. Enrichment factors between 2.5 and 5.0 times were found for both metals. This method was applied in the determination of the total contents: 3.70 - 31.98 and 15.71 - 126.1 μg L-1, of the nonvolatile fractions: 2.16 - 14.33 and 2.00 - 10.99 μg L-1 and of the volatile fractions: 1.54 - 20.54 and 13.71 - 115.1 μg L-1 of vanadium and nickel, respectively, in samples of ordinary gasoline. The methods developed in this work, present adequate analytical characteristics, such as; precision, accuracy, sensitivity, fastness and low waste production for the determination of metals in samples of petroleum industry interest using GF AAS.
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9
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SIDNEI DE OLIVEIRA SOUZA
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ANALYTICAL STRATEGIES USING CHEMIOMETRIC TOOLS FOR ANALYSIS OF HUMAN CONSUMPTION FOOD AND ANIMALS USING SPECTROMETRIC TECHNIQUES
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Leader : RENNAN GEOVANNY OLIVEIRA ARAUJO
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MEMBRES DE LA BANQUE :
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RENNAN GEOVANNY OLIVEIRA ARAUJO
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RODOLFO DE MELO MAGALHAES SANTANA
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DANIELE CRISTINA MUNIZ BATISTA DOS SANTOS
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MARIA DAS GRACAS ANDRADE KORN
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SARAH ADRIANA ROCHA SOARES
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FABIO DE SOUZA DIAS
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VICTOR CERDÀ MARTÍN
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ADRIANO DE ARAÚJO GOMES
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CLEBER GALVAO NOVAES
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TATIANE DE ANDRADE MARANHÃO
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Data: 26 avr. 2019
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In this work, three works were developed involving strategies for food analysis for determination of inorganic constituents in animal feeds and sugarcane juice samples, as well as, chemical speciation analysis of As, Sb and Se of dried fruits using atomic spectrometry. In the first work, simultaneous experimental designs were applied to optimize the conditions of microwave-assisted sample decomposition and operational of a spectrometer for animal feed analysis. Inductively coupled plasma (ICP) based methods were used to determine the concentrations of 23 chemical elements in feed for ornamental and human fishes, ruminants, wild birds, rabbits, equines and ruminants. The limits of quantification obtained ranged from 0.02 mg kg-1 (Cd) to 76 mg kg-1 (Al). The reliability to the methods was confirmed by the analysis of certified reference material of oyster tissue (NIST 1566b) and tea (NCS DC 73351). The concentrations obtained ranged between 0.038 mg kg-1 (Sb) and 3.37% (Ca) for ornamental fishes, <LoQ (Ba) and 2.0% (Ca), <LoQ (Cd, Pb and Sb) and 2.0% (Ca) for rabbits, <LoQ (Cd, Pb, Sb and Se) and 2,53% (Ca) for wild birds, 0.034 mg kg-1 (Sb) and 2.10% (Na) for equines and, <LoQ (Se) and 14% (Ca) for ruminants, all of which are in accordance with Brazilian and American legislation. In the second work, a multivariate optimization of a sample preparation procedure in slurry was used to determine Ca, Cu, Fe, K and Mg in sugarcane juice samples by inductively coupled plasma optical emission spectrometry (ICP OES). The simultaneous designs (fractional factorial and Doehlert) were applied to optimize the variables: HNO3 concentration, H2O2 volume, sonication time, nebulizer gas flow and radiofrequency power for direct analysis of the sample as slurry. The procedure was validated by comparing digestion with addition and recovery tests. The proposed analytical method was applied for analysis of fourteen samples of sugarcane juice marketed in Aracaju, Sergipe, Brazil. The mean concentrations (in mg L-1) of 108 (Ca), 0.51 (Cu), 6.40 (Fe), 470 (K) and 114 (Mg) were obtained. The methodology presented offers a simple, fast, easy and efficient of sample preparation form simultaneous determination of Ca, Cu, Fe, K and Mg in sugarcane juice by ICP OES, after prepared as slurry. Finally, in the third work, the chemical speciation analysis of As, Sb and Se in dried fruit samples was performed using multi-syringe flow injection analysis hydride generation atomic fluorescence spectrometry (MSFIA-HG-AFS). For As and Sb determinations, the concentrations of NaBH4, KI and HCl were evaluated as factors. For Se determination, only concentrations of NaBH4 and HCl were evaluated. The two optimizations were performed through Doehlert designs, having the intensities of As, Sb and Se as response. Limits of quantification ranged from 0.34 (Sb total) to 15 ng g-1 (As total). The accuracy and precision of the analytical methods were evaluated through the analysis of certified reference material and addition and recovery tests. The analytical methods were applied to nine dried fruit samples, and the highest concentrations (in ng g-1) were 8.2 ± 0.6 for Sb(III), 14.0 ± 1.2 for Sb(V), 102.5 ± 7.4 for Se(IV) and 90.5 ± 9.8 for Se(VI). The As(III) and As(V) species obtained concentrations below the LoQ for all samples. In this work, analytical methods for the determination of total concentrations of essential and potentially toxic elements in food and feeds, and can be used for routine analysis to ensure food safety.
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10
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MAURICIO BRANDAO DOS SANTOS
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synthesis of ZSM-5 by interzeolite transformation from Y zeolite
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Leader : ARTUR JOSE SANTOS MASCARENHAS
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MEMBRES DE LA BANQUE :
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ADRIANE VIANA DO ROSARIO
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ARTUR JOSE SANTOS MASCARENHAS
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HELOYSA MARTINS CARVALHO ANDRADE
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MARITZA MONTOYA URBINA
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SIBELE BERENICE CASTELLÃ PERGHER
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Data: 26 avr. 2019
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Afficher le Résumé
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Zeolites are materials strategically widely used in industrial processes of adsorption, separation or heterogeneous catalysis. Zeolites synthesis involves the use of silicon and aluminum sources, a mineralizing agent, and the use of structure directing agents (SDA), which may be inorganic and/or organic cations and organic molecule. The use of organic structure directing agents (OSDAs) despite having been a phenomenon of new structures, but is very costly for industrial purposes. In addition, the zeolites prepared in the presence of OSDAs require a step of burning the organic molecule, which requires a lot of energy and generates possible pollutant molecules. Thus, studies on the synthesis of zeolites without the use of organic directing have been encouraged as an alternative route, more promising from an economical and sustainable point of view. Seed use is another alternative, however, in many cases the seed is synthesized in the presence of organic molecules and the zeolitic phase of interest is not always obtained with the desired purity. In the last years, interzeolite transformation has returned to this scenario as an alternative to syntheses with OSDAs or with seeds due to shorter process time and cost. The two mechanistic routes proposed for the interzeolite transformation are sustained in thermodynamics by the Ostwald rule, according to which a given framework type evolves into a more dense structure, thermodynamically more stable structure, and kinetics, since they will preferably form, zeolites containing in their structure building units (CBUs, SBUs, RBUs) in common with the starting zeolite. However, there are some reports in the literature that counterpose these assertions. The studies carried out in this thesis indicate that the composition of the synthesis gel that favors the obtaining of the target topology can not be left aside. The approach based on both the Ostwald rule and the ring units building is the result of this composition and, therefore, the transformation can not be justified without correlating all the factors involved. Thus, even starting from a zeolite with SiO2/Al2O3 = 3 ratio,the addition of amorphous silica allowed to obtain units in 5-membered rings required to obtain the ZSM-5 and mordenite phases. However, the adjustment of the NaOH/SiO2 molar ratio was also preponderant because it enabled the control of the solubilization and repolymerization of the silicon and aluminum precursors that resulted in different zeolite pure phases such as ZSM-5, mordenite, analcima and cancrinite.
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11
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LEANE SANTOS NUNES
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Analytical strategies using liquid-liquid microextraction with drop drop for determination of Manganese and Vanadium in water, beverage and food samples
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Leader : MARIA DAS GRACAS ANDRADE KORN
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MEMBRES DE LA BANQUE :
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MARIA DAS GRACAS ANDRADE KORN
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RODOLFO DE MELO MAGALHAES SANTANA
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VALFREDO AZEVEDO LEMOS
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WALTER NEI LOPES DOS SANTOS
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CLEBER GALVAO NOVAES
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ANIBAL DE FREITAS SANTOS JUNIOR
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Data: 17 mai 2019
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Afficher le Résumé
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The present work reports on the development of two analytical methods for the determination of manganese and vanadium using atomic absorption spectrometry with graphite furnace and the colorimetry of digital images. Within this context, two papers were prepared. The first consisted of the development of two liquid phase microextraction approaches (LPME), direct immersion droplet microextraction (DI-SDME) and continuous flow microextraction (CFME) using the reagent 1- (2-pyridilazo) -2-naphthol (PAN) as complexing agent and 1-butyl-3-methylimidazolium hexafluorophosphate [C4MIM] [PF6] as the extraction solvent. The extraction efficiencies were compared. Some variables of the preconcentration system were optimized using the univariate method. The developed system presented limit of detection and quantification of 0.17 and 0.51 μg L-1, respectively, enrichment factor of 17.67. The accuracy of the method expressed as relative standard deviation (% RSD, n = 10) was 6.15 using a 1.0 μg L-1 Mn (II) solution. The accuracy of the method was evaluated by determination of manganese in certified reference material of mussel tissue (SEM 2976). The concentrations of manganese found in the certified samples ranged from 4.16 to 4.85 μg g-1.The second work involved the development of a system for determination of vanadium (V) in water samples using SDME-DC (digital colorimetry and colorimetry with digital images). The analyte of interest was extracted into one drop of the solvent hexafluorophosphate of 1 The chemical analyzes were performed in an ImajeJ program that employs an RGB (red-green-blue) primary color space with values ranging from 0 to 255. The RGB data were extracted from cropped digital images of sizes The data obtained by the red channel were used to construct the analytical curve, since it presented the highest sensitivity. Under optimized conditions, the method presented enrichment factors of 50, the detection limit obtained was 0.45 μg L-1 and the limit of quantification was 1.43 μg L-1. The accuracy of the method was assessed by the analysis of a reference material certifi BCR-414, Plankton, from the Institute for Reference Materials and Measurements (IRMM, Geel, Belgium).
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12
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MANOEL ALVES MACHADO FILHO
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Theoretical Study of Acid-Base Interactions Lewis and Reactive Processes in Compounds Organic
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Leader : ROBERTO RIVELINO DE MELO MORENO
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MEMBRES DE LA BANQUE :
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ALVARO SANTOS ALVES
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BOAZ GALDINO DE OLIVEIRA
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FERNANDO DE BRITO MOTA
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ROBERTO RIVELINO DE MELO MORENO
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SILVIO DO DESTERRO CUNHA
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TIAGO VINICIUS ALVES
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Data: 22 mai 2019
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In this thesis, we study theoretically (i) the acid-base Lewis interactions formed between carboxylic acids and CO2 and (ii) reactive processes in organic compounds, such as Knovenaegel reactions and aldol condensations, of great interest for several application areas, especially green chemistry. Our calculations were performed at the level of density functional theory (DFT) and Møller-Plesset second-order perturbation theory (MP2). In case the (i) we present theoretical evidences that Lewis acid-base interactions should occur for carboxylic acids adsorbed on silver, by interacting with CO2. In addition, the study of the Raman and vibrational spectra calculated supposing a supercritical CO2 condition show that surfaceenhanced Raman spectroscopic (SERS) can be used to characterize such interactions, contributing to the formation of new compounds and surfaces with potential adsorption for CO2. In the case (ii) mechanisms of organic reactions involving Meldrum's acid and substituted aromatic aldehydes were studied and elucidated in light of computational procedures and experimental evidence. The understanding of which species of Meldrum acid is more reactive in aqueous medium through the proposition of mechanisms was the first and decisive step so that the reactions with aromatic aldehydes could be characterized and their proposals and experimental results for multicomponent systems could be understood at the level molecular, enabling other forms of reaction, prediction of new results and the follow-up of principles of green chemistry
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13
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GISSELI SOUZA VALASQUES
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ANALYTICAL STRATEGIES USING EXTRACTION-INDUCED EXTRACTION INDUCED FOR QUANTIFICATION OF METAL AND METALOIDS IN OIL OIL
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Leader : ANA MARIA PINTO DOS SANTOS
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MEMBRES DE LA BANQUE :
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ANA MARIA PINTO DOS SANTOS
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MARIA ELISABETE MACHADO
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SERGIO LUIS COSTA FERREIRA
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CLEBER GALVAO NOVAES
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MARCOS DE ALMEIDA BEZERRA
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Data: 27 juin 2019
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Palm oil is an oily product of great interest to the food, cosmetics and biofuel industry. The presence of metals in this matrix is related to its oxidative stability, its nutritional value, the possibilities of contamination in the various stages of production, among other factors. The work presented in this paper deals with the development of analytical methods for the determination of metals and ametals in crude palm oil samples by atomic spectrometry techniques after emulsification assisted by ultrasonic energy followed by extraction induced by emulsion breaking (EIEB) as an alternative, simple, fast and efficient to the traditional processes of decomposition. In this context, the following works were carried out: (i) development of a method for the determination of Ca, Mg, Mn, Fe and Zn in oil crude palm oil by flame atomic absorption spectrometry (FAAS). The optimization of this method was done by constrained mixtures design and desirability function. The method have present limits of quantification between 0.018 and 0.19 mg L-1 and accuracy, expressed as repeatability (% RSD, N = 10) between 1.8 and 3.2% for the five metals studied. The accuracy of the method was achieved by applying addition/recovery tests of the analytes to the samples (obtaining recoveries between 87 and 113%) and by comparing the concentration values found by EIEB with the values found by dry decomposition, finding good agreement between these values. The application of the EIEB method in samples collected in the State of Bahia (Brazil) showed that the concentrations (mg L-1) of the samples were 3.93 to 13.9 (Ca), 0.37 to 2.26 (Mg), > LQ to 0.32 (Mn), 1.77 to 8.57 (Fe) and 0.38 to 2.54 (Zn); (ii) development of a method for the determination of As and Se in crude palm oil by atomic fluorescence spectrometry coupled to the hydrides generation (HG-AFS) and Hg by cold vapor generation (CV-AFS). Two-level fractional factorial design (25-1), Doehlert design and desirability function were used in the optimization process. The method presented limits of quantification of 0.72; 0.12 and 1.5 μg L-1 and accuracy expressed as repeatability (% RSD, N = 10, 5 μg L -1) of 1.7; 2.5 and 3.5% respectively for As, Hg and Se. The accuracy of the method was reached by addition / recovery tests (recoveries between 90 and 128%) and by comparison of the concentration values found by decomposition in Teflon® bombs, showing good agreement. The concentrations (μg L-1) of As, Hg and Se found in the samples were 1.28 to 1.58 (As) and 2.39 to 7.96 (Se). Concentrations of Hg were below LQ in the analyzed samples; (iii) development of a method for determination of Cd and Pb in crude palm oil by graphite furnace atomic absorption spectrometry (GFAAS). The method was optimized using Doehlert design and desirability function. The method have presented quantification limits of 0.16 and 0.12 μg L-1 and accuracy of 1.8 and 5.4% respectively for Cd and Pb. Accuracy was accessed by applying recovery/addition tests and values between 88.5 and 112% were obtained. Quantities of Cd and Pb respectively between 1.39 and 2.31 and 2.36 and 6.29 μg L-1 were found in the analyzed samples.
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14
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DANILO JUNQUEIRA LEÃO
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ANALYTICAL STRATEGIES FOR DETERMINING MERCURY IN ENVIRONMENTAL SAMPLES
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Leader : SERGIO LUIS COSTA FERREIRA
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MEMBRES DE LA BANQUE :
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SERGIO LUIS COSTA FERREIRA
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WALTER NEI LOPES DOS SANTOS
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VALFREDO AZEVEDO LEMOS
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ADRIANO DE ARAÚJO GOMES
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DÉBORA DE ANDRADE SANTANA
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Data: 28 juin 2019
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The present work is about the development of analytical strategies for the determination of mercury in environmental samples using atomic absorption spectrometry with cold vapor generation (CV AAS). Mercury is a metal known to be toxic to the health of humans and ecosystems, standing out to have this toxicity even in low concentrations. Several studies reported in the literature show the need for the development of new, more sensitive methodologies for determination and analysis of mercury speciation, since this analyte is characterized by trace concentrations and is one of the main current concerns when it comes to contamination environmental. Within this context, two papers were developed. The first one consisted in the development of a method of determination of mercury in sediment samples by optimization of a simple procedure of extraction of the analyte of the samples for later determination by CV AAS. Such optimization was performed using multivariate optimization techniques, evaluating the influence of the factors in the analyte extraction step. The factors evaluated were: hydrochloric acid concentration, thiourea concentration, sonication temperature and sonication time. After optimization, the accuracy of the method was confirmed by the analysis of two certified reference materials, Channel Sediment (BCR-320R) and San Joaquin Soil (NIST 2709a). The detection and quantification limits were 1.04 and 3.46 ng g-1, respectively, and the precision, in terms of RSD%, was 4.31%. The method was applied for the determination of mercury in sediment samples collected in the São Paulo Estuary, located in the state of Bahia, Brazil, whose concentrations ranged from 13.8 to 38.5 ng g-1. The second work involved the development of an automated system for the determination of mercury in natural water samples employing multiserial flow injection analysis (MSFIA) and cold vapor generation atomic absorption spectroscopy (CV AAS). The experimental conditions were investigated and optimized using multivariate optimization methodology, such as complete factorial design (2k) and Doehlert Matrix. The optimized variables were: hydrochloric acid concentration, sodium borohydride concentration, sample flow and entrainment gas flow. The proposed method allowed the direct determination of mercury in natural water samples, that is, without preconcentration stage, with limits of detection and quantification of 43.0 and 145.0 ng L-1, respectively. The accuracy of the method was confirmed by analysis of certified water reference material, Trace elements in waste water, (CASS-4). The matrix effect was evaluated by addition and recovery tests in saline water samples, as the method was optimized using aqueous standards, obtaining recoveries above 82%. The method was applied in a sample of sea water and lake of the city of Salvador, Bahia, Brazil, whose concentrations ranged from 0.36 to 1.14 μg L-1.
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15
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OSÉAS SILVA SANTOS
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N2O assisted methanol conversion over acid and base catalysts
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Leader : HELOYSA MARTINS CARVALHO ANDRADE
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MEMBRES DE LA BANQUE :
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ADRIANE VIANA DO ROSARIO
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ARTUR JOSE SANTOS MASCARENHAS
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CARINE TONDO ALVES
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HELOYSA MARTINS CARVALHO ANDRADE
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RAILDO ALVES FIUZA JUNIOR
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SUZANA MODESTO DE OLIVEIRA BRITO
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TEREZA SIMONNE MASCARENHAS SANTOS
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VALERIA CRISTINA FERNANDES
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Data: 28 juin 2019
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Nitrous oxide (N2O), a pollutant that contributes to the greenhouse effect and depletion of the ozone layer, is one of the main protagonists, along with methanol, in this study. In this sense, this work was developed to evaluate nitrous oxide as an oxidizing agent in basic and acidic reactions using methanol to obtain formaldehyde and dimethyl ether, respectively. In the basic catalysis catalysts of cobalt oxides derived from lamellar double hydroxides were used as catalysts for the conversion of methanol to formaldehyde in the presence of nitrous oxide. The catalysts were characterized by various techniques. The test results showed 100% methanol conversion and 91% selectivity to formaldehyde were simultaneously obtained with 100% N2O conversion at 440 ºC over a Co,Mg,Al-mixed oxide catalyst. Higher hydrogen yields and lower CO and CO2 yields were obtained than when air was used as oxidizing agent, under the same conditions. At another time, as a complementary study, these same oxides catalysts were prepared by inserting cerium by the co-precipitation method. In this study, Cobalt and Cerium doped oxides were characterized and tested in the selective catalytic oxidation of methanol assisted by N2O. It was obtained 100% methanol conversion, 100% N2O conversion and 91% formaldehyde yield were obtained on the CoMgAl catalyst. The catalysts containing cerium were more active in the conversion of N2O at lower temperatures (350 - 400 ºC), but presented lower formaldehyde yields, due to the increase of oxidation products (CO and CO2) formation. In general, the basic reaction with oxides derived from HDLs suggests that the reaction occurs on a combination of redox and basic catalytic sites. On the other hand, acidic catalysts were used for H-ZSM-5 and Co-ZMS-5 acid catalysts for the dehydration reaction of methanol to N2O-assisted dimethyl ether (DME). During this study, high conversion of methanol (78 %) and yield and selectivity to DME of 70 and 90 %, respectively, were obtained at 300 °C. During the stability test the Co-ZSM-5 catalyst was shown to be thermally stable and catalytically in the N2O/CH3OH reaction (1:3) with low generation of polyoxymethylene dimethyl ethers (POMEs) (<10%). In conclusion N2O acts in the removal of the carbon deposits avoiding the intensive coking of the acid catalyst. On the other hand, the formation of surface oxygen species due to N2O decomposition generated a higher number of moderate (or density) sites, contributing to the selective formation of DME. N2O can be used as an oxidizing agent in industrial processes of economic importance, such as assisting in the reaction of selective oxidation of methanol to formaldehyde or in the dehydration reaction of methanol to dimethyl ether.
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16
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ELISÂNGELA COSTA SANTOS
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CHEMICAL / GEOCHEMICAL CHARACTERIZATION OF SEDIMENTS OF THE LOW STRAIN OF THE SAN FRANCISCO RIVER TO ASSESS ENVIRONMENTAL IMPACTS
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Leader : VANIA PALMEIRA CAMPOS
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MEMBRES DE LA BANQUE :
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VANIA PALMEIRA CAMPOS
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MARIA ELISABETE MACHADO
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ANTONIO FERNANDO DE SOUZA QUEIROZ
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JOSE ROBERTO BISPO DE SOUZA
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YVONILDE DANTAS PINTO MEDEIROS
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RAILDO MOTA DE JESUS
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Data: 5 juil. 2019
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The low strain of the São Francisco river covers an area that divides between the States of Alagoas and Sergipe, in the stretch after the Xingó Dam, to its mouth, in the city of Sergipe. The objective of this work was to characterize, through chemical and geochemical parameters, the sediments of the low strain of the São Francisco River, in order to evaluate possible environmental impacts. Samples of surface sediments were collected during three seasons, two in dry season (February 2014 and December 2015) and one in the rainy season (July 2016), in the two margins of four transects, totaling 8 sampling points. Core samples of sediments were collected in 7 localities (Pão de Açúcar-AL, Niterói-SE, Traipu-AL, Gararu-SE, Xinaré-AL, Pindoba-SE, Ilha das Flores-SE) in July 2016 at the depths of 2 to 44 cm, to verify the influence of the dams on sedimentation behavior. The Environmental Protection Agency's analytical procedure, EPA 3051A, was applied to the sediments and trace elements were determined by inductively coupled plasma optical emission spectrometry (ICP OES). The origin and sources of organic matter (OM) were evaluated using elemental ratios by elemental analysis coupled to mass spectrometry. The results obtained after partial decomposition of the sediment samples in microwave oven and determination by ICP OES were evaluated through guideline values established by sediment quality guides. It was possible to infer that the samples collected in the low strain of the São Francisco river presented clayey minerals of the kaolinite and ilite type. Concentrations of As in PA-AL (2014) and IF-SE (2015, 2016) were above the criteria of the values for TEL (Threshold Effect Level) and PEL (Probable Effect Level). The concentrations obtained for Cd in PA-AL, GA-SE, IF-SE (2014 to 2016), NI-SE, XI-AL, PI-SE (2014 and 2016), TA-AL (2016) and PE-AL (2015 and 2016) were above the minimum value established by the Canadian and US legislation, TEL and LEL (Lowest Effect Level). In PA-AL (2014) and NI-SE (2016) the values exceeded that established by the Canadian legislation (PEL). In IF-SE (2016) the values are above the limits established by the US legislation, SEL (Severe effect level). The concentration values found for Cr in sediments of SE-SE (2016) presented levels above the lower thresholds established by the American legislation (LEL). The calculated potential ecological risk index reflects great concern in the NI-SE and IF-SE locations, since it was between moderate to high in 2016. By the calculated ecological risk factor for the different locations in the different periods, it can been that the elements As, Cr, Cu, Ni and Pb offer greater ecological risk. In relation to phosphorus, it was observed that a decrease in the flow rate for the NI-SE, TA-AL, GA-SE, XI-AL, PE-AL and IF-SE discharges resulted in an increase in P concentration in the sediment. The results on the origin and source of OM related to the sediments of the Low strain of the São Francisco river revealed different constitutions composed of bacteria, marine algae and C3 plants. The stable isotopes δ13C and δ15N evidenced the presence of sewage, fertilizers, cyanobacteria and OM typical of the estuary. In this way, it is inferred that the work carried out warns about the need for a monitoring in the region of the low strain of the São Francisco river, since the reduction of the flow is more felt by the localities closest to the mouth, due to the decrease of fresh water in relation to the entrance of the sea water, occurring accumulations of OM, fertilizers and trace elements. The work also contributed to the generation of a database on the composition and quality of sediments of the low strain of the São Francisco River
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17
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EDUARDO BATISTA GUIMARÃES NUNES DOS SANTOS
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Exploring solid phase of Al(OH)3 produced in situ by homogeneous precipitation assisted by microwaves radiation for fast extraction of chemical species
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Leader : MAURO KORN
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MEMBRES DE LA BANQUE :
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MAURO KORN
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RENNAN GEOVANNY OLIVEIRA ARAUJO
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DANIELE CRISTINA MUNIZ BATISTA DOS SANTOS
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MADSON DE GODOI PEREIRA
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DÉBORA DE ANDRADE SANTANA
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Data: 5 juil. 2019
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The aluminum hydroxide precipitation in homogeneous solution assisted by microwave radiation for the extraction of organic compounds, coprecipitation of metallic ions and inorganic anion species removal were studied. Unlike what occurs in conventional precipitations, where the precipitant is added, facilitating the production of colloids, precipitation in homogeneous solution produces more pure crystals that are rapidly agglomerate, speeding up the filtration of solids. When irradiating with microwaves, the urea solutions in the presence of aluminum ions leads to the formation of overheating zones and the fast decomposition of urea causes a local pH increasing and the production of Al(OH)3 in situ, which aids to separate other chemical species from the solution. In order to investigate the ability to organic compounds separation with the solid phase produced in situ, some experiments were carried out to extract neutral and electrically charged dyes. The results showed that the Al(OH)3 had a strong affinity for neutral organic compounds, with extraction rates higher than 80% for Congo red dye, betacarotene, humic acid and curcumin. The extraction of phenolic compounds by the proposed separation process was studied and the removal capacities for quercetin, quercitrin, morin, kaempferol, rutin, caffeic acid, ferulic acid, dopamine, L-dopa and chlorogenic acid from aqueous solutions were estimated. As, only quercetin was quantitatively removed with the precipitate (> 99%), an alternative process was developed for the separation and preconcentration of quercetin in aqueous extracts of onion sample without using organic solvents. Studies about the coprecipitation of metallic cations and anions separations during the Al3+ in situ precipitation process were carried out. The coprecipitation of metals by homogeneous precipitation of microwave assisted Al(OH)3 was evaluated in aqueous solutions and brines. Higher recovery rates (> 70%) were obtained for Cr, Fe, Pb and Cu, allowing the determination of Cr and Fe contents in brine samples by atomic spectrometric techniques without the interference of sodium. The proposed irradiation coprecipitation process was applied to evaluate the feasibility of trace metal determination in commercial samples of special salts for culinary uses (black salt, flakes of flower of salt and Himalayan pink salt). Higher separation rates for Cr and Fe were estimated for flower of salt and pink salt samples due to the high sulfur content characteristic of the black salts. Finally, the transfer of large inorganic anions (phosphate and dichromate) from aqueous solutions to the Al(OH)3 produced from homogeneous microwave-assisted precipitation was evaluated and an efficient phosphate extraction to Al(OH)3 solid phase in solutions without chloride and nitrate ions was obtained (> 99%). Phosphate ions determination in fertilized vegetal soil samples and cola soft drink were evaluated and the results indicated strong matrix effects due to competition between organic compounds and inorganic anion. The effect of dichromate ion presence in aqueous and brine solutions were also evaluated.
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18
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JEFERSON DO ROSARIO ALMEIDA
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The integration of Nanomaterials in the Cell Wall of Filamentous Fungi for the production of biohybrid and biomimetic materials.
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Leader : MARCOS MALTA DOS SANTOS
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MEMBRES DE LA BANQUE :
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PAULO ROBERTO RIBEIRO DE JESUS
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LILIAN MARIA TOSTA SIMPLICIO RODRIGUES
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MARCOS MALTA DOS SANTOS
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REGINA MARIA GERIS DOS SANTOS
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ANTONIO FERREIRA DA SILVA
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HAMILTON BRANDÃO VARELA DE ALBUQUERQUE
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ARNAUD VICTOR DOS SANTOS
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MADSON DE GODOI PEREIRA
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Data: 26 juil. 2019
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The present work aims to integrate nanomaterials to the cell wall of filament fungi, aiming the production of luminescent biohybrid materials and semiconductor biomorphic materials. In order to obtain luminescent biohybrid materials, fungi of the species Aspergillus niger, Phialomyces macrosporus and Trichoderma spp were grown in a medium containing luminescent lanthanide metal-organic framework (Tb-MOFs and Eu-MOFs). The biohybrid was characterized by scanning electron microscopy (SEM), fluorescence optical microscopy and luminescence spectroscopy that revealed integration of the MOFs in the cell wall of the three fungal species. Fluorescence light microscopy images also showed that MOF particles are also transported to the intracellular region of the fungi and are stored in the vacuoles. The internalization of the MOFs in the intracellular region of the fungi opens a vast field for the application of these materials in the treatment of infectious fungi. To produce biomorphic materials, the biohybrids of the fungus Phialomyces macrosporus and titanium oxide (anatase) were submitted to a hydrothermal treatment (100-140 ° C) in alkaline medium (10M NaOH solution). The XRD measurements associated with SEM images, transmission electron microscopy (TEM) and X-ray dispersive energy (EDS) showed the production of microtubes made from sodium titanate nanotubes. The variation of NaOH concentration (6.5 to 8.0 M) allowed the formation of microtubes composed of sodium titanate nanoribbons. A mechanism has been proposed for the formation of nanoribbons on the biomorphic structure that takes into account the slow degradation of the cell wall components and adhesive substances that keeps the TiO2 particles bound to the fungal hyphae.
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19
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THIAGO FONTES DA HORA SILVA
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SÍNTESE MECANOQUÍMICA DE ARILIDENOS, CUMARINAS E 4-CLOROACETANILIDA
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Leader : SILVIO DO DESTERRO CUNHA
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MEMBRES DE LA BANQUE :
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SILVIO DO DESTERRO CUNHA
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JORGE MAURICIO DAVID
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VALERIA BELLI RIATTO
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LOURENCO LUIS BOTELHO DE SANTANA
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AMENSON TRINDADE GOMES
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Data: 26 juil. 2019
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Afficher le Résumé
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The Mechanochemistry is based on the use of mechanical energy to promote breakage and bond formation due to high pressure and temperature increase by friction, usually in the absence of solvent, being used in carbon-carbon, carbon-heteroatom, oxidation, reduction, condensation, coupling and organometallic synthesis. Using dedicated laboratory equipment, its application on sophisticated synthetic routes became more reliable due to the control of the energy transferred to the reagents and, thus, greater reproducibility, thus arousing the interest of organic-synthetic scientists. In this work a bibliographic review was made on the use of mechanochemistry in Organic Synthesis, and a study of some reactions between Meldrum's acid and aldehydes with donor substituents and electron withdrawals. Some reactions lead to the formation of arylidenes while others lead to the formation of coumarin acids, due to the presence of a hydroxyl in the 2 position of benzaldehyde, both of which are reactions of Knoevenagel where the compound with active hydrogen (carbanion) is Meldrum’s acid. In the development of the methodology to obtain coumarinic acids an experimental design of central compound and multi-response analysis was performed to optimize the reaction conditions. In addition, we developed the first mechanochemical synthesis of 4-chloroacetanilide as an effective alternative to the experimental class of Green Organic Chemistry.
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20
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KLEBSON SOUZA SANTOS
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Photodegradation of cyanide species in wastewater from cassava flour production with simultaneous fuels production assisted by photocatalysts TiO2.Nix.NiO
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Leader : LUCIANA ALMEIDA DA SILVA
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MEMBRES DE LA BANQUE :
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RAILDO ALVES FIUZA JUNIOR
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LUCAS BOMFIM BOLZON
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LUCIANA ALMEIDA DA SILVA
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ALEXILDA OLIVEIRA DE SOUZA
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SUZANA MODESTO DE OLIVEIRA BRITO
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Data: 19 août 2019
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Damage to water bodies is considered one of the biggest environmental problems today. In view of this, several advanced technologies are being developed for the treatment of contaminating effluents and industrial waters. In this context, the present work focused on the development of a photocatalytic system capable of treating the wastewater from cassava flour production, an effluent rich in cyanide species and other organic compounds, aiming to reduce the pollutant load and, at the same time to recover part of the biomass energy remaining from the tubercle processing. This study involved the synthesis of nickel-doped TiO2 by the sol-gel method, using different concentrations of Ni, followed by thermal treatment in oxidizing and oxidizing/reducing atmosphere. The materials prepared were characterized by X-ray diffractometry, scanning electron microscopy and diffuse reflectance spectroscopy, later used as photocatalysts in the photocatalytic treatment of manipueira water in a bench reactor and argon atmosphere, irradiated with light λ > 370 nm. The results obtained after photocatalytic treatment for 5 hours demonstrate a decrease in the concentration of cyanide species from 8.93 mg L-1 of total cyanide to 5.18 mg L-1 when treated with pure TiO2 and 0.19 mg L-1 when treated with TiO2.Ni/NiO (sample obtained with 25% (m / m) Ni followed by heat treatment in an oxidizing atmosphere). The monitoring of the gaseous effluents produced during the degradation of the cyanide species and organic matter identified the presence of molecular hydrogen and ethene. The ethene production rate was in the range of 0.0667 to 1.029 μmol g-1 h-1 for nickel doped materials at different concentrations and the production of this gas was not detected when pure TiO2 was used. On the other hand, hydrogen production range was from 2.0761 μmol g-1 h -1 using TiO2 doped with 25% (m) of Ni with hydrogen to 0.0985 μmol g-1 h-1 for pure titanium dioxide.
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21
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MILENA DE SANTANA SANTOS
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PEROVSKITAS BASED ON NICKEL, COBALT AND LANTHANUM APPLIED ON THE PARTIAL OXIDATION OF METHANE AND COMBUSTION BY CHEMICAL CYCLE
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Leader : SORAIA TEIXEIRA BRANDAO
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MEMBRES DE LA BANQUE :
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SORAIA TEIXEIRA BRANDAO
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LILIAN MARIA TOSTA SIMPLICIO RODRIGUES
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RAILDO ALVES FIUZA JUNIOR
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JAIME SOARES BOAVENTURA FILHO
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MARLUCE OLIVEIRA DA GUARDA SOUZA
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Data: 30 août 2019
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Afficher le Résumé
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Perovskite with composition LaNi1-xCoxO3 (x = 0.0, 0.2, 0.5, 1.0) were studied in the partial oxidation of methane (POX), in the total oxidation (combustion) by chemical looping and in the catalytic combustion of methane. These samples were synthesized by the citrate method and characterized by different methods, such as XRD, specific area by the BET method, TPR-H2, TPSR-CH4, XPS, TEM, TGA, Raman spectroscopy were evaluated by TPSR-CH4/O2 and by long term tests under different conditions. In POX, the main results indicate that the mechanism of transformation of oxides LaNi1-xCoxO3 (x = 0.2 and 0.5) under atmosphere of CH4 and O2 is dependent on the oxide composition (x = 0.2 and 0.5) and pretreatment conditions (in this case, x = 0.2). The sample (x = 0.5), independent of previous H2 treatment, evidence of the formation of intermediate phases La2BO4 (B = Ni and CO) was noted. However, with the sample (x = 0.2) the mechanism involves the formation of the spinel phases (La2BO4) only in the condition that there was no pretreatment with H2. In all experiments, the phase changes of the oxides (LaNi1-xCoxO3 and Ni1-xCox/La2O3) under atmosphere of CH4 and O2 resulted in the Ni1-xCox/La2O3 system. The performance of the catalytic tests in different conditions with the sample (x = 0.2) suggested that the pretreatment with H2 favors the synthesis gas at a H2/CO ratio closer to the theoretical value (2) when compared to the pre-treatment treatment with the reaction mixture (CH4 + O2). During the tests no evidence of catalyst deactivation was observed, but the reaction of OPM contributed to the formation of graphite carbon on these materials. The LaNi0.5Co0.5O3 oxide showed better performance during the chemical cycle combustion tests, this sample led to the complete reduction in a shorter time as well as showed less susceptibility to deactivation due to the formation of coke in the catalytic combustion of methane, all samples were active, it was verified that the addition of cobalt contributed to obtain a more stable catalyst.
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22
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MILENA DE SANTANA SANTOS
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PEROVSKITAS BASED ON NICKEL, COBALT AND LANTHANUM APPLIED ON THE PARTIAL OXIDATION OF METHANE AND COMBUSTION BY CHEMICAL CYCLE
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Leader : SORAIA TEIXEIRA BRANDAO
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MEMBRES DE LA BANQUE :
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JAIME SOARES BOAVENTURA FILHO
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LILIAN MARIA TOSTA SIMPLICIO RODRIGUES
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MARLUCE OLIVEIRA DA GUARDA SOUZA
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RAILDO ALVES FIUZA JUNIOR
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SORAIA TEIXEIRA BRANDAO
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Data: 30 août 2019
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Afficher le Résumé
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Perovskite with composition LaNi1-xCoxO3 (x = 0.0, 0.2, 0.5, 1.0) were studied in the partial oxidation of methane (POX), in the total oxidation (combustion) by chemical looping and in the catalytic combustion of methane. These samples were synthesized by the citrate method and characterized by different methods, such as XRD, specific area by the BET method, TPR-H2, TPSR-CH4, XPS, TEM, TGA, Raman spectroscopy were evaluated by TPSR-CH4/O2 and by long term tests under different conditions. In POX, the main results indicate that the mechanism of transformation of oxides LaNi1-xCoxO3 (x = 0.2 and 0.5) under atmosphere of CH4 and O2 is dependent on the oxide composition (x = 0.2 and 0.5) and pretreatment conditions (in this case, x = 0.2). The sample (x = 0.5), independent of previous H2 treatment, evidence of the formation of intermediate phases La2BO4 (B = Ni and CO) was noted. However, with the sample (x = 0.2) the mechanism involves the formation of the spinel phases (La2BO4) only in the condition that there was no pretreatment with H2. In all experiments, the phase changes of the oxides (LaNi1-xCoxO3 and Ni1-xCox/La2O3) under atmosphere of CH4 and O2 resulted in the Ni1-xCox/La2O3 system. The performance of the catalytic tests in different conditions with the sample (x = 0.2) suggested that the pretreatment with H2 favors the synthesis gas at a H2/CO ratio closer to the theoretical value (2) when compared to the pre-treatment treatment with the reaction mixture (CH4 + O2). During the tests no evidence of catalyst deactivation was observed, but the reaction of OPM contributed to the formation of graphite carbon on these materials. The LaNi0.5Co0.5O3 oxide showed better performance during the chemical cycle combustion tests, this sample led to the complete reduction in a shorter time as well as showed less susceptibility to deactivation due to the formation of coke in the catalytic combustion of methane, all samples were active, it was verified that the addition of cobalt contributed to obtain a more stable catalyst.
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23
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RAVIR RODRIGUES FARIAS
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Use of the copper catalyzed azide-alkine cicloading methodology in the synthesis of symmetric bis-triazoles. Investigation of it’s physical, biological characteristics and as a binder
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Leader : MAURICIO MORAES VICTOR
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MEMBRES DE LA BANQUE :
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ELIANA MIDORI SUSSUCHI
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JORGE MAURICIO DAVID
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MAURICIO MORAES VICTOR
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ROSSIMIRIAM PEREIRA DE FREITAS
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SILVIO DO DESTERRO CUNHA
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Data: 4 oct. 2019
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Copper-catalyzed azide-alkyne cycloaddition reactio, known as CuAAC reaction, has been investigated in the synthesis of symmetric bis-triazoles from terminal diazides and alkynes. The conditions for obtaining the desired products have been optimized: Copper catalyst sources and the stoichiometric relationship between terminal diazids/alkynes were investigated in the CuAAC methodology. This research aimed to symmetric bis-triazoles and the investigation of their physical, biological and ligand properties. The manipulation allowed the formation of the 4-substituted alkyl-phenyl bis-triazoles in moderate to excelente yields. However, the optimized methodology applied to oxygenated alkynes did not work or led to low yield products. The best result for antifungal activity was obtained by bis-triazole 170 which presented the same fluconazole® MIC (32 μg.mL-1) against Candida Krusei ATCC 6258, na emerging and potentially multiresistant fungal pathogen. Due to its versatility of biological activity, five hydroxyl bis-triazoles showed no inhibition of leishmanicidal activity between 15.0 and 20.0 %, at concentrations of 20 and 40.0 μg.mL-1. Among these compounds, derivative 172 presented the best value of IC50 (63,34 μg.mL-1, 182,86 μM). Regarding cytotoxicity, all compounds were inactive. It was also observed through infrared spectra, the effect of presence and absence of H binding on the triazole ring characteristic bands. In addition, in order to verify the stability of diazids, the termal study was performed using the DSC technique, diazide 154 presented na exothermic event at a temperature of approximately 130.0 °C. 1,3-Bis(4-butyl-1H-1,2,3-triazol-1-yl) propan-2-ol 158 was successfully applied as a binder for the determination of Cu(II) ions by electrode modified in cultivated with bordeaux treatment. The detection limito f the method (LOD) and the limit of quantification (LOQ) were 1,67x10-9 mol.L-1 and 5,05x10-9 mol.L-1, respectively, and the amount of ions of copper found in a real sample of was 8,05 μg.kg-1, a value within the standards stipulated by ANVISA.
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24
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WILSON ELIAS ROZO NUÑEZ
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MECHANOCHEMICAL STUDY OF THE REACTIVITY OF 3,4-DIBROMOFURAN-2(5H)-ONA IN THE SYNTHESIS OF HOMO-ALDOIS AND HETEROPOLICYCLES
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Leader : SILVIO DO DESTERRO CUNHA
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MEMBRES DE LA BANQUE :
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ANDRE ALEXANDRE VIEIRA
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CAIO COSTA OLIVEIRA
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KLEBER THIAGO OLIVEIRA
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MAURICIO MORAES VICTOR
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SILVIO DO DESTERRO CUNHA
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Data: 11 oct. 2019
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In this thesis, a study of furanone reactivity against different nucleophiles such as phthalimide, cyanide salts, ammonium thiocyanate, sodium iodide and sodium azide was performed. In this way it was possible to obtain high purity derivatives without the need for chromatographic purification and high yield. In addition, we also explored the mechanochemical synthesis of homoaldols, furobenzopyranones, and coumarin and 1,2,3-triazole hybrids. The mechanochemistry allowed to perform transformations in the absence of solvent and shorter reaction times. For the first time, the mechanochemical synthesis of furanone-derived homoaldols is described, with yields ranging from 22 to 67%. A mechanochemical method was developed for obtaining the nucleus of 2Hfuro[3,2-b]benzopyran-2-one, creating a library of 11 molecules, of which two are coumarin hybrids. The yields ranged from 44 to 91%. Due to the fluorescence of these molecules, their photophysical properties were evaluated and showed promising results. The classic Pechmann method for the synthesis of coumarins was optimized. By this procedure at least 10 molecules can be obtained.
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25
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LEILA MARIA MENDES SANTOS
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Photocatalytic remediation of organophosphate pesticide using ZnO and TiO2 based photocatalysts and a natural clay
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Leader : LUCIANA ALMEIDA DA SILVA
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MEMBRES DE LA BANQUE :
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LUCIANA ALMEIDA DA SILVA
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JOICY SANTAMALVINA DOS SANTOS
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PEDRO AFONSO DE PAULA PEREIRA
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JEANCARLO PEREIRA DOS ANJOS
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SUZANA MODESTO DE OLIVEIRA BRITO
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Data: 29 nov. 2019
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In recent years pesticide use has become intense to meet the food demand of the world's growing population. The increase in the generation of more pesticide residues requires an effective and sustainable approach capable to degradate these environmental pollutants. A process based on the photocatalysis is presented in this work as a sustainable, efficient and low cost alternative for remediation of this type of pollutant. In this context, the photocatalytic activity of toxic metal-free materials with potential use of solar power was evaluated in the degradation of fention, an organophosphate pesticide. The photocatalysts evaluated were pure and nitrogen-doped TiO2 and ZnO (TiO2-N and ZnO-N), as well as in the form of composites with a hematite-rich natural clay (TiO2/Tauá and ZnO/Tauá, where tauá is a Brazilian indigenous word that means red clay). The photocatalysts were prepared by sol-gel and Pechini methods of synthesis. X-ray diffraction analysis has confirmed the presence of TiO2 and ZnO phases in the doped materials and composites, which were also characterized by SEM, EDX and DRS. The study of surface chemistry by the adsorption method was able to identify the ideal pH condition for better photocatalytic activity. The photocatalysts were irradiated with visible and ultraviolet light aided with the oxidant H2O2. The monitoring of fention concentration during irradiation was performed using a spectrophotometric method after dichloromethane extraction. ZnO/Tauá and TiO2/Tauá composites were the most active photocatalysts when compared to individual components and doped oxides, reaching 90.3% and 87.0% photodegradation, respectively. The optimization of reaction parameters for the most active photocatalyst (ZnO/Tauá) resulted in fention photodegradation within 30 minutes when the initial pesticide concentration was 30 mg L-1 and the H2O2 concentration was 100 mg L-1.
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26
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FRANCIELE OLIVEIRA SANTANA
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Gaseous contaminants/pollutants in the atmosphere of Brazilian urban centers.
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Leader : VANIA PALMEIRA CAMPOS
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MEMBRES DE LA BANQUE :
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VANIA PALMEIRA CAMPOS
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PEDRO AFONSO DE PAULA PEREIRA
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MARCOS DE ALMEIDA BEZERRA
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MARTA VALERIA ALMEIDA S. DE ANDRADE
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PÉROLA DE CASTRO VASCONCELLOS
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Data: 6 déc. 2019
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Gases and particulate matter as atmospheric contaminants/pollutants affect the health of the city populations, causing serious damage to the fauna/flora, building materials and monuments. Vehicle emissions have been considered the predominant source of air quality degradation in large cities. In 2018, ambient air pollution caused 4.2 million deaths worldwide. This work comparatively evaluated the concentrations of 16 atmospheric pollutants / gaseous contaminants from 5 Brazilian urban centers (São Paulo, Salvador, Rio de Janeiro, Belo Horizonte e Londrina), with intense vehicular flow and different characteristics, such as location type (coastal or noncoastal), demographic density and weather conditions, use of passive sampling. Six simultaneous passive sampling campaigns were performed using the AnalyseAr kit for consecutive periods of 7 and 14 days. BTEX compounds were quantified by gas chromatography (GC) with flame ionization detection (FID); HCOH and CH3COH by high performance liquid chromatography (HPLC) with UV-Vis detection; NOx, NO2, NH3 and H2S by molecular spectrophotometry and SO2, O3, HCl, HNO3, HCOOH and CH3COOH by ion chromatography (IC). O3 was the gaseous pollutant with the highest concentration in the city of São Paulo, 58 µg m-3 , ranging from 5.3 to 139 µg m-3 in all the centers. In terms of average levels of atmospheric concentration, most compounds presented higher concentrations in the dry period. São Paulo and Belo Horizonte showed higher concentration levels, corroborating the intensity of the vehicle fleet, allied to meteorological parameters; specifically NOx levels, which exceeded the European Union recommendation (30 µg m-3 ). Formaldehyde and acetaldehyde exceeded international recommendations in all urban centers and benzene concentrations showed values > 1.7 μg m-3 , a level associated with the probability of leukemia, according to the World Health Organization (WHO). The ratios Toluene / Benzene (T/B), Xylenes / Benzene (X/B), m, p-Xylenes / Ethylbenzene (m,p-X/E) and Formaldehyde / Acetaldehyde (FA/AA) indicated that vehicle emissions are the main sources of these Volatile Organic Compounds (VOCs) in the atmosphere of Brazilian urban centers. The cancer risk probability for adults that were exposure to those atmospheres was above the 1.0 x 10-6 , exceed the limit established by the USEPA for both benzene, and for formaldehyde. The emission of diesel vehicles was considered the predominant source for the increase of nitrogen oxide concentrations. NH3 concentrations indicated a significant contribution of anthropogenic emissions from biofuel use, industrial sectors or fertilizer. Urban centers with influence of marine aerosol presented lower concentrations of HNO3, indicating occurrence of reaction of this acid with NaCl in sea spray particles, producing particulate matter and HCl(g). Direct discharges of sewage into water bodies, when present at the sites, contributed to an increase in H2S, toluene and NH3 levels. Ratios between the concentrations of formic and acetic acid and strong positive correlations between nitrogen pollutants, conventional pollutants and VOCs between them indicated significant influence of vehicular emissions in the atmosphere of these urban centers. Organic and inorganic acids presented a similar contribution to atmospheric acidity, with acetic acid most abundant in most of the centers studied. Multivariate analysis showed that VOCs and organic acids are more influenced by temperature and solar radiation parameters. The strongest direct relationship of NOx was with wind direction, shown competition between in loco emission and photochemical aging of these compounds brought from other locations. In general, vehicular emissions are the predominant sources of gaseous pollutants in the urban atmosphere and photochemical reactions combined with meteorological parameters contribute to the seasonal variation of the levels of these pollutants/contaminants.
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27
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WILSON BITENCOURT BARRETO JÚNIOR
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INVESTIGATION OF PHOTOCATALYTIC ACTIVITY OF TiO2 BASED MATERIALS AND STUDY OF
ATRAZIN PHOTODECOMPOSITION.
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Leader : ADRIANE VIANA DO ROSARIO
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MEMBRES DE LA BANQUE :
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ADRIANE VIANA DO ROSARIO
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ARTUR JOSE SANTOS MASCARENHAS
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RAILDO ALVES FIUZA JUNIOR
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GILBERTO ABATE
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LUCIANA BAGDEVE DE OLIVEIRA DOS SANTOS
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TEREZA SIMONNE MASCARENHAS SANTOS
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Data: 6 déc. 2019
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Titanium dioxide (TiO2) is one of the most used semiconductors due to its excellent characteristics and because it can be applied in many areas, specially in photocatalysis. TiO2 has a band gap of 3.2 eV, meaning an absorption in near UV–UVA region, limiting its use. In addition, the high recombination rate of the photogenerated charge carriers, damage its performance. Therefore, it is necessary to increase its absorption spectrum and to produce modifications on the oxide that avoid the charge carriers recombination process. One alternative is the addition of others transition metals to the oxide synthesis, either by doping or by the mixed phases formation. In this work, Zn2+ and W6+ ions were added to the TiO2 synthesis by the Pechini method. Two photocatalysts groups, Zn-TiO2 and W-TiO2, were prepared with different dopant concentrations and at different temperatures (500oC and 700oC). Initially, the catalysts were tested using a model compound (methylene blue – MB), in order to investigate the photoactivity of these materials, and after use them in the study of the decomposition of the atrazine (ATZ) herbicide. AM and ATZ photodegradation processes were monitored by UV-Vis spectroscopy and high efficiency liquid chromatography (HPLC) techniques. Semiconductors were characterized by x-ray diffraction (XRD), diffuse reflectance and BET-surface area. These studies allowed us to evaluate the photoactivity of the synthesized materials and to relate the catalytic behavior with their structural and optical characteristics. The addition of Zn2+ and W6+ leads to different effects on TiO2 structural properties. For the heat treatment at 700oC, the increase of Zn2+ addition induced the partial conversion of the anatase phase to rutile and for the higher Zn2+ concentration levels, a ZnTiO3 phase segregation occurred. In the case of the W-TiO2 system synthesized at the same temperature, the increasing on the W6+ concentration reduced the anatase phase particle size and the conversion of the anatase to rutile. At high W6+ concentrations, a WO3 segregate phase also to arise. Both systems showed improvement of photocatalytic activity in the decomposition of MB. However, the best results were presented by samples containing W6+. Exceptionally, samples with high W6+ amount showed catalytic activity in the absence of UV and visible light. Atrazine photodegradation was performed with the samples that demonstrated the greatest potential for application. The best results were obtained with the catalyst sample containing 2.0 mol% of W6+, whereby the atrazine concentration was reduced in 37% in the first 60 min and was almost completely consumed after 420 min. During the ATZ decomposition process, the degradation products desethylatrazine (DEA) and desethyldesisopropyl-atrazine (DE-DIA) were detected.
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28
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FREDSON SANTOS GUIMARÃES
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Cracking and hydrocracking of soy oil on acidic and basic catalysts for obtaining biofuels.
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Leader : ARTUR JOSE SANTOS MASCARENHAS
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MEMBRES DE LA BANQUE :
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ARTUR JOSE SANTOS MASCARENHAS
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HELOYSA MARTINS CARVALHO ANDRADE
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LUCIANA ALMEIDA DA SILVA
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ROGER THOMAS FRANCOIS FRETY
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TEREZA SIMONNE MASCARENHAS SANTOS
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Data: 10 déc. 2019
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Most of all the energy consumed in the world comes from oil, coal and natural gas. These sources are limited and are expected to be depleted. Thus, the search for alternative sources of energy is of paramount importance. The use of fuels derived from biomass has been identified as an alternative, reducing the dependence on fossil fuels for both economic and environmental reasons. The global concern with climate change also extends to air transport, which has few alternatives to conventional fuels due to its dependence on liquid fuels with high energy density, which allow long flight autonomies without increasing the weight and the volume to be transported. There is a wide variety of raw materials with different plant and animal sources, such as soybeans, babassu, canola, oil palm, pork fat, among others, and conversion processes that can potentially be used for the production of aviation biofuels. Among the raw materials used, vegetable oils stand out. The cracking of vegetable oils is a promising route in obtaining biofuels. The process takes place at temperatures above 350 ° C, in the presence or absence of catalyst. In this reaction, the breakdown of the triglyceride molecules leads to the formation of a mixture of hydrocarbons and oxygenated compounds, in addition to carbon monoxide and dioxide and water. Catalysts with acidic and basic characteristics have been investigated in the cracking of vegetable oils. Among these, we can highlight zeolites and oxides derived from layered double hydroxides. Zeolites have acidity, size and pore distribution that make them very active and selective in the catalytic cracking of vegetable oils. Already oxides derived from double layered hydroxides, with basic properties, are indicated for deoxygenation via decarbonylation, where oxygen is eliminated as CO. In order to improve the properties of biofuel, hydrocracking was a good alternative to reduce the amount of oxygenates in the product obtained. This reaction took place in the presence of acid catalysts (zeolites, HZSM-5 containing 2, 5 and 10% nickel and HMCM-22 containing 2%) and basic (oxides derived from lamellar double hydroxides). These catalysts proved to be effective for cracking (except MgAl-LDH) and hydrocracking to produce a biofuel in the kerosene range, however with considerable oxygenate content.
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VIVIANA OLIVEIRA MATEUS
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CATALISADORES DE FERRO E MOLIBDÊNIO SUPORTADOS EM CARVÃO ATIVADO PARA REAÇÃO DE HIDROGENÓLISE DE DERIVADOS DE BIOMASSA
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Leader : ARTUR JOSE SANTOS MASCARENHAS
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MEMBRES DE LA BANQUE :
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ARTUR JOSE SANTOS MASCARENHAS
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ADRIANE VIANA DO ROSARIO
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RAILDO ALVES FIUZA JUNIOR
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LUIZ ANTONIO MAGALHAES PONTES
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RODRIGO DE PAULA
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Data: 11 déc. 2019
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The insertion of matter from inexhaustible sources is required by commerce and therefore industry. Biomass has emerged as a promising alternative in the diversification of the industrial platforms, the transformation of biomass directed to processes that guarantee competitive prices in relation to those coming from fossil fuels is desirable. Acid catalysts are required in the process in order to favor the hydrolysis of cellulose in the hydrogenolysis reactions of cellulose to aid in the formation of sugars and the dehydration of glycerol to acrolein in the hydrogenolysis reactions of glycerol, for example. In contrast, the metallic characteristics of the catalysts tend to favor hydrogenation leading to the formation of 1,2 and 1,3 propanediol in the hydrogenolysis reactions of glycerol and sorbitol in the hydrogenolysis reactions of the cellulose. Commonly, hydrogenolysis is employed in the sense of providing breakage of the C-C and C-O bonds that make up the structure of the biomass such as cellulose and glycerol. The effects of the acidic and metallic characteristics of the catalysts, therefore, tend to favor the process of breaking the rigid bonds present in the cellulose, as well as in the direction of the reactions of hydrogenolysis of the glycerol, the formation of chemical inputs much required by industry as propene under conditions reactions. The catalysts containing molybdenum and iron supported on charcoal seem to be a promising route, as it has acidic and textural characteristics that probably favor the conversion of cellulose, as well as that of glycerol. The use of the activated carbon in this case, to favor the dispersion of the catalysts and, therefore, the availability of the active centers to react. In this context, the study of iron and molybdenum catalysts supported on activated carbon for the reaction of hydrogenolysis of biomass derivatives (hydrogenolysis of cellulose and hydrogenolysis of glycerol) was studied and the many appreciable characteristics for its use in these reactions were explained. Hydrogenolysis of glycerol at 500 ºC proved to be more promising for obtaining propylene in catalysts containing molybdenum, while at 300 ºC it proved to be more selective for obtaining methane, ethane, ethylene or CO. Propylene production yielded 15% of the total 6 hours of reaction at 500 ºC for CMF. The post-test characterization of catalysts submitted to 300 ºC and 500ºC indicated that the phases discussed in the TPR in the characterization were obtained and, therefore, the Fe2MoO4, Fe2Mo3O8, FeMoO4, MoO2, Fe phases in the samples containing molybdenum and iron, as well as the Mo8O23 phase were observed. The TG post catalytic test indicated the presence of a large amount of oxides for all cases. Hydrogenolysis of cellulose carried out at 205ºC has shown promise in obtaining HMF and furfural molecules at 50 bar. The catalyst CF indicated favoring the formation of glycerol, CM to HMF and furfural and CMF to the formation of HMF and acetol mainly. The results indicated that acidity governs the reaction, as well as the active phase. These results indicate that hydrogenation was favored in the CF catalyst, while CM and CMF probably occurred in hydrogenolysis. The 50 bar pressure may have favored the in situ reduction of the catalyst and possibly the mechanisms of cellulose hydrogenolysis were favored for CM and CMF.
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