Fast Fourier Transform
Mostrando 1-12 de 88 artigos, teses e dissertações.
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1. 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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2. 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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3. Identification of Synthetic Drugs on Seized Blotter Papers Using ATR-FTIR and PLS-DA: Routine Application in a Forensic Laboratory
Blotter papers seizures containing synthetic drugs have intensified over the last decades. These drugs were originally conceived as “legal” alternatives to traditional illicit drugs, designed to mimic their effects and circumvent control agencies. Reference methods for determining these substances on blotter papers are based on chromatographic techniques
J. Braz. Chem. Soc.. Publicado em: 2021-03
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4. Synthesis, Characterization, and Synergic Photocatalytic Activity of Amorphous TiO2/Chitosan Carbon Microspheres
In this work, we report the synthesis and characterization of new amorphous graphene-like TiO2/chitosan carbon microspheres and its performance as photocatalyst. Four different carbon chitosan microspheres materials were obtained based on the distinctive procedure to incorporate TiO2 and TiOSO4 to chitosan structure by pyrolysis at 600 °C. Detailed characte
J. Braz. Chem. Soc.. Publicado em: 2020-06
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5. USE OF PAPER SPRAY-MASS SPECTROMETRY TO DETERMINE THE CHEMICAL PROFILE OF RIPE BANANA PEEL FLOUR AND EVALUATION OF ITS PHYSICOCHEMICAL AND ANTIOXIDANT PROPERTIES
In this work, the peels of ripe banana (Musa sp.), variety “Prata”, were used to prepare a flour, which was evaluated for its physicochemical characteristics and antioxidant activity. The characterization of its chemical profile was performed by a fast and simple method: paper spray-mass spectrometry. This flour had high carbohydrate content and total di
Quím. Nova. Publicado em: 2020-05
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6. BIODIESEL SYNTHESIS FROM WASTE COOKING OIL USING A VARIETY OF WASTE MARBLE AS HETEROGENEOUS CATALYSTS
Abstract The research article is based on biodiesel synthesis by the transesterification of waste cooking oil with methanol in the presence of heterogeneous catalysts prepared from different marble. Eight samples of marble were successfully converted into potential catalysts by calcination. The thermal treatment of waste marbles at 300oC-1000oC converted the
Braz. J. Chem. Eng.. Publicado em: 13/01/2020
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7. Comparação entre simulação e sistema real de vibração com dois graus de liberdade
Resumo Na engenharia, compreender corretamente os elementos que compõem os sistemas vibratórios e a física envolvida nestes é fundamental no projeto de estruturas e máquinas, por exemplo. Embora em muitos casos, no estudo de sistemas vibratórios não seja possível analisar o sistema somente com um grau de liberdade, sistemas com dois graus ou mais sã
Rev. Bras. Ensino Fís.. Publicado em: 20/05/2019
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8. Correção de distorções harmônicas em sistemas elétricos através de interferência destrutiva
Resumo Neste trabalho será apresentado um método didático e alternativo para correção das distorções harmônicas em sistemas elétricos de corrente alternada. Primeiramente será apresentado o problema das distorções harmônicas e como quantificá-las através da série de Fourier. Em seguida, métodos experimentais para a correção das distorçõe
Rev. Bras. Ensino Fís.. Publicado em: 04/02/2019
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9. Surface Imprinting of Silica Gel by Methyldopa and Its Application in the Solid Phase Extraction Procedure
An imprinted amino-functionalized silica gel material was prepared by surface molecular imprinting technique combined with a sol-gel process on the supporter of activated silica gel and used as a solid-phase extraction for the extraction and determination of methyldopa (MTD). Non-imprinted silica adsorbent was synthesized without the addition of MTD using th
J. Braz. Chem. Soc.. Publicado em: 2018-02
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10. The Long-Range Memory and the Fractal Dimension: a Case Study for Alcântara
ABSTRACT: This study aimed to analyze the time series behavior of the Southern Oscillation Index through techniques using Fast Fourier Transform, computing the autocorrelation function, and the calculation of the Hurst coefficient. The methodology of Hurst Exponent calculation uses different lags, which are computed in the time series of Southern Oscillation
J. Aerosp. Technol. Manag.. Publicado em: 24/08/2017
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11. Detection of Counterfeit Durateston® Using Fourier Transform Infrared Spectroscopy and Partial Least Squares - Discriminant Analysis
Medicines containing anabolic steroids are one of the main targets for counterfeiting worldwide, including Brazil. The aim of this work was to propose a method for discriminating original and counterfeit Durateston® ampoules by Fourier transform infrared spectroscopy (FTIR) followed by chemometric analysis. Ninety-six ampoules of Durateston®, 49 originals
J. Braz. Chem. Soc.. Publicado em: 2017-07
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12. Manufacture of nanosized apatite coatings on titanium with different surface treatments using a supersaturated calcification solution
The biomimetic method is used for the deposition of calcium phosphate coatings (Ca - P) on the surface of different biomaterials. However, the application of this method requires long exposure times in order to obtain a suitable layer thickness for its use in medical devices. In this paper, we present a fast approach to obtain apatite coatings on titanium, u
Quím. Nova. Publicado em: 2016-12