Microwave
Mostrando 13-24 de 901 artigos, teses e dissertações.
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13. What is new in non-chromatographic flavonoid purification?
Flavonoids are metabolites occurring in all plant tissues and present different biological activities. They occur in a mixture of similar polarity with laborious separation and purification processes, usually furnishing low yields. Semi-preparative chromatographic methods are universally employed procedures for their isolation. This paper discusses the state
Química Nova. Publicado em: 2022
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14. Green Synthesis of Upconverting NaYF4 and NaGdF4 Materials and Energy Levels Determination
An alternative green route using a domestic microwave oven to synthesize NaGdF4:Yb,Tm and NaYF4:Yb,Er was successfully developed. Decreasing dopants concentration increased the β-NaREF4/α-NaREF4 ratio in NaGdF4. The scanning electron microscopy (SEM) images of NaGdF4 showed particles ranging from 500 nm to 1 μm with formation of aggregates up to 100 μm,
J. Braz. Chem. Soc.. Publicado em: 2021-08
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15. Direct steam injection pretreatment improves microwave-assisted extraction yield for total flavonoids and myricetin from Hovenia dulcis Thunb.
Abstract A direct steam injection pretreatment was added before the microwave-assisted extraction procedure for the extraction of flavonoids from seeds of Hovenia dulcis Thunb, and the antioxidant activity of flavonoid extracts was determined. Based on the experimental results, the addition of direct steam injection simultaneously increased the extraction yi
Food Sci. Technol. Publicado em: 2021-06
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16. Expansibility of vermiculite (Santa Luzia, Brazil) irradiated with microwave
Abstract The effect of microwave heating on the expansion of vermiculite was studied at a level of 700 W for 4 min exposure time and compared with raw vermiculite. In this study, the characterization of vermiculite from a mine in the northeast region of Brazil was performed using thermogravimetry, N2-adsorption, cation exchange capacity, X-ray powder diffrac
Cerâmica. Publicado em: 2021-06
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17. Expedient Microwave-Assisted Synthesis of Bis(n)-lophine Analogues as Selective Butyrylcholinesterase Inhibitors: Cytotoxicity Evaluation and Molecular Modelling
In the brain of patients with chronic Alzheimer’s disease (AD), the butyrylcholinesterase (BuChE) levels rise while the acetylcholinesterase (AChE) levels decrease. Therefore, development of new selective BuChE inhibitors is of vital importance. Here we present a series of bis(n)-lophine analogues, where two lophine derivatives are connected by a methylene
J. Braz. Chem. Soc.. Publicado em: 2021-06
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18. Solventes eutéticos naturais profundos (NADES) no preparo de amostras de rocha fosfática e suplemento mineral para determinação elementar por técnicas de plasma
Natural deep eutectic solvents (NADES) based on xylitol, citric acid, and malic acid were synthesized and used in ultrasound-assisted extraction (UAE) and heating-bath extraction of phosphate rock and mineral supplement samples. Arsenic, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, P and Zn were determined by inductively coupled plasma mass spectrometry (ICP-MS) and i
Quím. Nova. Publicado em: 2021-06
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19. Design, Synthesis and Antifungal Activity of New Schiff Bases Bearing 2-Aminothiophene Derivatives Obtained by Molecular Simplification
Seventeen Schiff bases bearing 2-aminothiophene derivatives were designed and synthesized using molecular simplification. The resulting compounds (4a-4q) were evaluated for their in vitro antifungal activity against dermatophytes. Prediction of their druglikeness and pharmacokinetic properties, establishment of their structure-activity relationships (SAR), a
J. Braz. Chem. Soc.. Publicado em: 2021-05
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20. Hemostasia rápida: um procedimento ambulatorial novo e eficaz utilizando ablação por micro-ondas para controlar a epistaxe de lesões isoladas protuberantes da mucosa
Resumo Introdução Epistaxe recorrente é comumente encontrada no ambulatório de rinologia. Sob orientação endoscópica, foram empregados tanto o cautério bipolar quanto a pinça monopolar (combinados à sucção) para controlar a condição. No entanto, o uso de pinças monopolares requer a colocação de placas de aterramento. Atualmente, a maioria d
Braz. j. otorhinolaryngol.. Publicado em: 2021-05
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21. Microwave-Assisted Acid Digestion: Evaluation of Reaction Vessel Design and Performance
Nowadays, microwave-assisted procedures using closed vessels with thermal, chemical, and mechanical resistance are the state-of-the-art for efficient digestion of samples. Safety issues related to sample reactivity should be considered and analytical throughput is also a critical parameter. The choice of a specific vessel for a target application is not triv
J. Braz. Chem. Soc.. Publicado em: 2021-04
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22. Investigation of ultrasound pretreatment time and microwave power level on drying and rehydration kinetics of green olives
Abstract In this study, the effect of ultrasound (US) combined microwave (MW) drying of green olive slices was studied. Olive samples were exposed to ultrasound (5 and 10 minutes; 32 KHz) at room temperature before dried at microwave at 3 different power level (180W, 450 W and 800 W). The drying and rehydration characteristics and quality parameters of olive
Food Sci. Technol. Publicado em: 2021-03
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23. Study of structural, optical, and morphological characteristics of manganese titanate (MnTiO3) obtained by combustion reaction using microwave energy
Abstract MnTiO3 is a semiconductor that has relevant dielectric and optical properties. For the synthesis of manganese titanate (MnTiO3) powders, the combustion method via microwave and subsequent calcination at 500, 700, and 900 °C were used. The structural, morphological, and optical properties of the samples were investigated. X-ray diffraction analyzes
Cerâmica. Publicado em: 2021-03
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24. Sample Preparation Using TMAH and Nitric Acid for Multielement Determination in Crustacean Samples by MIP OES
This study proposes a simple sample preparation procedure using tetramethylammonium hydroxide (TMAH) and nitric acid (HNO3) to determine Cr, Cu, Fe, K, Mg, Mn, and Zn concentrations in shrimp (Macrobrachium amazonicum) and crab (Ucides cordatus) samples from the Amazon region by microwave-induced plasma optical emission spectrometry (MIP OES). The sample sol
J. Braz. Chem. Soc.. Publicado em: 2021-03