Magnetic Resonance Spectroscopy
Mostrando 25-36 de 938 artigos, teses e dissertações.
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25. Evaluation of the Oxidation Degradation Process of Biodiesel via 1H NMR Spectroscopy
Biodiesel is a suitable alternative to replace the petro-diesel. The biodiesel is formed by unsaturated esters easily degraded by interferences of oxygen, temperature, contact with metals or contaminants. The aim of this research was to investigate the biodiesel degradation process via 1H nuclear magnetic resonance (NMR) spectroscopy, observing the olefinic,
J. Braz. Chem. Soc.. Publicado em: 2020-08
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26. APRESENTAÇÃO - História Antiga: Diferentes Perspectivas
Biodiesel is a suitable alternative to replace the petro-diesel. The biodiesel is formed by unsaturated esters easily degraded by interferences of oxygen, temperature, contact with metals or contaminants. The aim of this research was to investigate the biodiesel degradation process via 1H nuclear magnetic resonance (NMR) spectroscopy, observing the olefinic,
Rev. Bras. Hist.. Publicado em: 2020-08
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27. 1H NMR and Chemometric Methods to Estimate the Octane Number in Brazilian C Gasolines
Brazilian gasoline type C can be purchased with octane number as the main difference. This quality parameter directly affects the price. Intermediate formulations may not be easily distinguished from conform samples due to similarity in visual appearance and physicochemical properties. The use of anhydrous ethanol as an additive also influences the octane va
J. Braz. Chem. Soc.. Publicado em: 2020-08
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28. New Diesters Derived from Piperine: in silico Study and Evaluation of Their Antimicrobial Potential
Piperine, previously extracted from black pepper (Piper nigrum L.), was used as a precursor for the synthesis of twelve new diester derivatives. The final products were obtained through the bimolecular nucleophilic substitution reaction (SN2) of the alkyl 2-chloroacetates and the salt of piperic acid, obtained from the basic hydrolysis of piperine. The compo
J. Braz. Chem. Soc.. Publicado em: 2020-08
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29. REGRESSÃO MULTIVARIADA POR OPLS E PLS DOS ESPECTROS DE RMN DE 1H DE MISTURAS DIESEL/BIODIESEL DE MAFURRA PARA ESTIMATIVA DO TEOR DE BIODIESEL
Two methodologies were developed to monitor the biodiesel content of mafurra in mixtures with diesel using hydrogen nuclear magnetic resonance (1H NMR) Spectroscopy combined with the multivariate regression by orthogonal projections to latent structure (OPLS) and partial least squares (PLS). The efficiency of these methodologies was analyzed based on the fig
Quím. Nova. Publicado em: 20/07/2020
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30. Synthesis, in silico Study and Antimicrobial Evaluation of New Diesters Derived from Phthaloylglycine
New diesters derived from phthaloylglycine (7a-7i) were synthesized and their structures characterized by infrared, 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. The compounds were evaluated in an in silico study, which demonstrated positive features indicating a possible drug candidate. The diesters showed antifungal activity ranging from modera
J. Braz. Chem. Soc.. Publicado em: 2020-05
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31. A Protocol for Fish Lipid Analysis Using Nuclear Magnetic Resonance Spectroscopy
This article reports on an easy-to-follow methodology for fish lipids analysis, including the biological sample collection, lipid extraction, sample preparation, nuclear magnetic resonance (NMR) spectroscopy analysis and statistical data analysis, with details on parameters used for the NMR analysis and the care needed in each step execution. As an example o
J. Braz. Chem. Soc.. Publicado em: 2020-04
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32. Near-Infrared Luminescence from Visible-Light-Sensitized Ruthenium(II)-Neodymium(III) Heterobimetallic Bridged Complexes Containing Alkoxy(silyl) Functional Groups
New infrared emitting d-f (ruthenium(II)-neodymium(III)) heterobimetallic complexes with alkoxy(silyl) functional groups have been prepared. Visible excitation evidenced energy transfer processes from the ruthenium(II) donor to neodymium(III) acceptors leading to infrared emission. Energy transfer rates (kEnT) and efficiency of energy transfer (ηEnT) are, r
J. Braz. Chem. Soc.. Publicado em: 2020-04
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33. Synthesis of Glycerol-Derived 4-Alkyl-Substituted 1,2,3-Triazoles and Evaluation of Their Fungicidal, Phytotoxic, and Antiproliferative Activities
Herein, the synthesis of nine novel glycerol-derived 4-alkyl-substituted 1,2,3-triazoles, using the CuI-catalyzed alkyne-azide cycloaddition reaction as the key step, is reported. The triazoles were characterized by infrared and nuclear magnetic resonance (NMR 1H and 13C) spectroscopy and mass spectrometry. The nine prepared compounds were evaluated with reg
J. Braz. Chem. Soc.. Publicado em: 2020-04
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34. Identifying New Isatin Derivatives with GSK-3β Inhibition Capacity through Molecular Docking and Bioassays
The semi-synthesis of 11 isatin derivatives was achieved through bimolecular nucleophilic substitution and click chemistry. Seven new compounds were obtained. All chemical structures were determined by infrared spectroscopy (IR), nuclear magnetic resonance spectrometry (NMR) and high-resolution mass spectrometry (HRMS) data. These derivatives were evaluated
J. Braz. Chem. Soc.. Publicado em: 2020-03
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35. EVALUATION OF THE METABOLIC PRODUCTION OF THE ENDOPHYTIC FUNGUS Phomopsis sp.
Endophytic microorganisms have been shown to be an important source of bioactive compounds, and much has been studied about their metabolites. For example, compounds with different biological activities have been isolated from Phomopsis sp. The metabolic study of this genus may lead to a better understanding of the routes of production of metabolites of inte
Quím. Nova. Publicado em: 2020-03
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36. Pumilacidins A-E from Sediment-Derived Bacterium Bacillus sp. 4040 an Their Antimicrobial Activity Evaluation
Marine strains of Bacillus are known to produce secondary metabolites different from that accumulated by their terrestrial counterparts, for example, lipopeptides such as surfactins, iturins and fengycins, which exhibit a variety of biological activities. Another important class of lipopeptides are pumilacidins, identified specially from Bacillus pumilus str
J. Braz. Chem. Soc.. Publicado em: 2020-02