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Mostrando 1-12 de 7686 artigos, teses e dissertações.
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1. Phenolic Compounds from Leaves of Cariniana estrellensis (Raddi) Kuntze (Lecythidaceae): A Brazilian Atlantic Forest Tree
Cariniana estrellensis (Raddi) Kuntze seedlings have been used in forest restoration programs in the Atlantic Forest biome. However, despite the economic and ecological relevance of this species, to date no general method for rapid identification of primary and secondary metabolites of C. estrellensis leaves has been reported. In this work, we explore the fe
Journal of the Brazilian Chemical Society. Publicado em: 2023
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2. Catalysts Derived from Thermal Treatments of Hydrocalumite-Type Compounds: Synthesis and Application in Transesterification Reactions
Catalyst performance is a relevant factor in biodiesel production because it can affect the efficiency of the process. This work provides a study of the performance of heterogeneous catalysts for biodiesel production derived from thermal-treated hydrocalumite-type compounds. This work aimed to synthesize and characterize hydrocalumite-type compounds intercal
Journal of the Brazilian Chemical Society. Publicado em: 2023
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3. Carbon Dots from Pilosocereus gounellei for Fluorimetric Determination of Tannin in Tea Using a Flow-Batch System
In this study, xiquexique (Pilosocereus gounellei) native endemic cactus from the Brazilian semiarid was used for the first time as a natural carbon source (“green precursor”) for the synthesis of highly fluorescent carbon dots (CDs). These CDs were successfully used to develop a fast, low-cost, eco-friendly fluorescence method for the determination of t
Journal of the Brazilian Chemical Society. Publicado em: 2023
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4. Study of Catalytic Pyrolysis of Biomass Sorghum (Sorghum bicolor L. Moench) Using Design of Experiments and Surface Response Methodology
This study proposes a screen of variables that have an influence on the modification of the bio-oil chemical composition as a unique critical quality attribute (CQA) throughout the pyrolytic process (zeolite, ZSM-5) by using a 24 full factorial design, followed by optimization through a response surface methodology (RSM) based on central composite design (CC
Journal of the Brazilian Chemical Society. Publicado em: 2023
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5. Phase Adjustment of S-Parameters from Coupled Resonator Filters
Abstract This paper presents a method to cancel the constant phase loading and transmission line that are added to the S-parameters of coupled resonant networks. Thus, the phase-corrected S-parameters may be used to obtain a rational model together with its representative coupling matrix. This method is applicable to lossy and lossless coupled resonator netw
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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6. A química analítica aplicada aos estudos de pigmentos rupestres: uma revisão
Instrumental advances have been employed in the study of archeological remains such as prehistoric rupestrians paintings with the objective of chemically characterizing them in order to reconstruct the cultural technologies of a prehistoric human group and/or to support conservation science studies. The analytical techniques most commonly used in archaeometr
Química Nova. Publicado em: 2022
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7. TANINOS E FLAVONOIDES DAS FLORES DE EUGENIA UNIFLORA (MYRTACEAE)
Eugenia uniflora, popularly known as pitanga, is a native species of the Brazilian flora, widely used in folk medicine for the treatment of various diseases and which has several bioactive chemical constituents. The aim of this work was to analyze the chemical composition of flowers visited by bees from Eugenia uniflora by Ultra-Performance Liquid Chromatogr
Química Nova. Publicado em: 2022
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8. A MEMORY-BASED ARGUMENT FOR NON-REDUCTIONISM ABOUT THE TRANSTEMPORAL IDENTITY OF PERSONS
Abstract Does memory constitue diachronic identity? Or does it presuppose it? Butler has claimed that it is the latter, and, in this paper, I will side with him. My argumentation, however, will take a different route. My claim is not that memory presupposes transtemporal identity because I can only remember episodes that have happened to me. Rather, I will p
Manuscrito. Publicado em: 2022
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9. A High-Selectivity Bandpass Filter Using Dual-Mode Coupling Resonator
Abstract In this work, a new model of high selectivity dual-mode bandpass filter is presented. The proposed filter consists of a set of coupled lines with a dual-mode adjustable response in its design process. An improvement in selectivity is presented by combining the dual-mode element with a classic band rejection structure, thus making it possible to intr
Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Publicado em: 2022
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10. Fast Catalytic Pyrolysis of Tetradecanoic Acid: Formation of Ketones as Intermediate Compounds in the Production of Hydrocarbons
This work aimed to compare two different catalysts in the production of a long chain ketone, intermediate in the production of hydrocarbons, during pyrolysis of tetradecanoic acid as a model fatty acid. The studied variables were the temperature, 450 and 600 ºC, and catalysts, γ-Al2O3 and Nb2O5, the latter has never been studied under such conditions. Pyro
Journal of the Brazilian Chemical Society. Publicado em: 2022
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11. AVALIAÇÃO DE METAIS POTENCIALMENTE TÓXICOS EM CHORUME PROVENIENTE DE ÁREA DE DEPOSIÇÃO DE RESÍDUOS SÓLIDOS EM BELÉM - PARÁ
The formation of solid waste is a global challenge regarding environmental preservation. Due to the lifestyle of modern society, which aims to improve practicality, new products are constantly being released in the market and increasing the formation of waste. The decomposition of waste from various origins produces a dark liquid named leachate, which presen
Química Nova. Publicado em: 2022
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12. Evaluation of sediment contamination by urban sewage in a stretch of Capibaribe River, Pernambuco, Brazil
Anthropic activities are responsible for the increase in environmental contamination, especially in aquatic systems, demanding studies to assess and monitor contamination levels in different water bodies. We have done a chemical characterization of eleven sediments in order to evaluate the level of contamination by domestic sewage from the Capibaribe River,
Química Nova. Publicado em: 2022