Isomers
Mostrando 1-12 de 709 artigos, teses e dissertações.
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1. VIBRATION CHARACTERISTICS, CHEMICAL BONDS AND WEAK INTERACTIONS OF 4- AND 5-HYDROXYSALICYLIC ACID INVESTIGATED BY TERAHERTZ SPECTROSCOPY AND DENSITY FUNCTIONAL THEORY
The terahertz (THz) absorption spectra of 4- and 5-hydroxysalicylic acid were measured by terahertz time-domain spectroscopy (THz-TDS) in the range of 0.4-2.8 THz. The unit cells of both were calculated by density functional theory (DFT), and the theoretical simulation and experimental data were basically in agreement. To further interpret the origin of the
Química Nova. Publicado em: 2022
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2. In vivo Administration of Testosterone Propionate in Cattle Analyzed by High Performance Liquid Chromatography-Tandem Mass Spectrometry: An Enzymatic Hydrolysis Study and Drug Abuse Issues
This study involved an animal experiment in which testosterone propionate was intramuscularly injected into four steers, and the ensuing urine samples were analyzed using high-performance liquid chromatography-tandem mass spectrometry. The enzymatic hydrolysis conditions were analyzed using analysis of variance (ANOVA) and response surface methodology employ
Journal of the Brazilian Chemical Society. Publicado em: 2022
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3. Mitigación de la formación de acrilamida en papas fritas tipo chips mediante la adición de antioxidantes fenólicos de Inca muña (Clinopodium bolivianum)
The aim of this study was to evaluate the influence of Inca muña phenolic antioxidants in the reduction of acrylamide (AA) in potato chips. The potatoes were cut into 2 mm thick slices, the addition of antioxidants was evaluated by immersion at atmospheric pressure and by vacuum impregnation (VI) at 80 kPa for 10 min. In both cases, two antioxidant concentr
Química Nova. Publicado em: 2022
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4. Valorization of Hesperidin from Citrus Residues: Evaluation of Microwave-Assisted Synthesis of Hesperidin-Mg Complex and Their Insecticidal Activity
The aim of the current study was the valorization of hesperidin, the dominant flavonoid in citrus processing waste, by microwave-assisted synthesis of hesperidin-Mg complex, improving its antioxidant activity and insecticidal potential. Here we show, for the first time, that microwave-assisted synthesis of [Mg(hesp)2(phen)]OAc (1) (hesp: hesperidin, phen: ph
Journal of the Brazilian Chemical Society. Publicado em: 2022
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5. Thermal and Catalytic Fast Pyrolysis of Oily Extracts of Microalgae: Production of Biokerosene
Three different microalgae species, Desmodesmus sp., Nannochloropsis oculata and Halamphora coffeaeformis were grown under controlled conditions. The resulting dry biomass was characterized by TG-DTA (thermogravimetry-differential thermal analysis) and extracted with three solvents having different polarities. The extracts gross mass yields varied from 2% us
J. Braz. Chem. Soc.. Publicado em: 2021-04
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6. Blue Glow Sticks: Cinnamic Acids and Arylacrylonitriles with Liquid-Crystalline Properties and Highly Fluorescent
Five new π-conjugated chromophores derived from acrylic acid and acrylonitrile were synthesized and their thermal and photophysical behaviors were analyzed. They were designed and synthesized through Knoevenagel condensations between arylacetylenebenzaldehydes and a methylene group activated from cyanoacetic and malonic acids. The characterization of the ta
J. Braz. Chem. Soc.. Publicado em: 2021-01
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7. One-Step Isolation of Monoterpene Indole Alkaloids from Psychotria leiocarpa Leaves and Their Antiviral Activity on Dengue Virus Type-2
The leaf MeOH extract of Psychotria leiocarpa (Rubiaceae) showed in vitro non-cytotoxic and anti-dengue virus serotype 2 (DENV2) activity in human hepatocarcinoma cell lineage (HepG2). A one-step and cost-effective reversed-phase solid-phase extraction method based on high-performance liquid chromatography (HPLC) parameters allowed the isolation, directly fr
J. Braz. Chem. Soc.. Publicado em: 2020-10
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8. TÉCNICAS AVANÇADAS PARA A DIFERENCIAÇÃO DE ISÔMEROS POR ESPECTROMETRIA DE MASSAS
Mass spectrometry (MS) is a powerful and widespread technique but is inherently uncapable to differentiate species with same m/z ratio. For this reason, many classical approaches were developed based on differential fragmentation patterns in tandem MS. More recently, new techniques for isomer identification in MS were developed, and we highlight the photodis
Quím. Nova. Publicado em: 2020-09
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9. Evaluation of α- and β-Endosulfan Residues in Teas and Yerba Mate Infusions by Bar Adsorptive Microextraction and Large Volume Injection-Gas Chromatography Mass Spectrometry
Tea and yerba mate are traditional beverages prepared through the infusion of leaves of Camellia sinensis and Ilex paraguariensis, respectively. During this process, the leaching of pesticides onto the beverage, such as endosulfan, may occur. In this study, a bar adsorptive microextraction (BAµE) method prior to large gas chromatography mass spectrometry an
J. Braz. Chem. Soc.. Publicado em: 2020-03
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10. Determination of Catechol and Hydroquinone by Using Perilla frutescens Activated Carbon Modified Glassy Carbon Electrode
High specific surface area activated carbon prepared by Perilla frutescens (PFHSAAC) was modified on the surface of the glassy carbon electrode (GCE) by drop-coating method to construct a PFHSAAC/GCE. The electrochemical properties of the modified electrode were investigated in detail by some electrochemical methods such as cyclic voltammetry (CV), different
J. Braz. Chem. Soc.. Publicado em: 2020-01
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11. PERFIL METABÓLICO DOS EXTRATOS POLARES DAS FOLHAS, GALHOS E CASCAS DE Copaifera multijuga HAYNE (COPAÍBA MARI-MARI DA AMAZÔNIA) POR ESI-EM
Copaifera multijuga Hayne is the main species of the genus in the Amazon region, being exploited for copaiba oil production mainly because of its therapeutic properties. The plant parts (leaves, branches, and barks) are widely used in folk medicine. However, they are little explored in terms of chemical composition. In this study, the polar extracts of leave
Quím. Nova. Publicado em: 2020-01
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12. Antimicrobial and antibiofilm activity of Cymbopogon flexuosus essential oil microemulsions
ABSTRACT The objective of the study was to determine the antimicrobial activity antibiofilm and to identify the main components of the essential oil (EO) obtained from the leaves of Cymbopogon flexuosus. The antibacterial and antibiofilm activity was determined against Staphylococcus aureus ATCC 29213, Pseudomonas aeruginosa ATCC 27853, Salmonella Typhimuriu
Rev. Ceres. Publicado em: 11/11/2019