Microwave Radiation
Mostrando 1-12 de 99 artigos, teses e dissertações.
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1. 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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2. Microwave radiation influence on the thermal and spectroscopic properties of Na-birnessite-type material
Resumo No presente trabalho, apresenta-se um estudo da influência da radiação micro-ondas nas propriedades térmica e espectroscópica, assim como estrutural (ordem-desordem) e morfológica, de óxido de Mn estruturado em camada tipo Na-birnessita. A rota empregada para obtenção da matriz lamelar foi a precipitação redox. Os produtos foram caracteriza
Cerâmica. Publicado em: 14/11/2019
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3. Influence of high-frequency microwave radiation on montmorillonite structure parameters
Resumo A influência da radiação micro-ondas nas alterações estruturais das partículas de montmorilonita foi estudada em uma amostra de argila montmorilonítica. Processos de longo alcance em múltiplas escalas foram induzidos nos aluminossilicatos naturais por radiação de micro-ondas de baixa e média potência (2,45 Hz, 750 W, 10 min). Amostras em p
Cerâmica. Publicado em: 14/11/2019
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4. Recovery of chitin and chitosan from shrimp waste with microwave technique and versatile application
RESUMO: Neste estudo, a quitina e a quitosana foram extraídas de resíduos de Litopenaeus vannamei utilizando métodos químicos e do micro-ondas. Os resíduos de camarão foram limpos, secos e peneirados a 16, 32 e 60 mesh, e as amostras foram despigmentadas, desmineralizadas e desproteinizadas. Posteriormente, a quitina foi submetida a processo de desacet
Arq. Inst. Biol.. Publicado em: 28/10/2019
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5. Investigation of Thermal Effects in Coaxial Probe Method and Dielectric Characterization of Glycerol up to 140°C
Abstract Dielectric properties of a material are of paramount importance in many areas of knowledge. All scientific fields that deal with the interaction of electromagnetic radiation with matter demand this information. Consequently, suitable methods for obtaining accurate dielectric data are required. In the microwave community, the dielectric metrology wit
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2019-03
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6. Development of a microwave absorbing material based on molybdenum-doped niobium pentoxide
Abstract This work aimed to perform the characterization of electrical properties of niobium pentoxide, Nb2O5, pure and doped with molybdenum, prepared by powder metallurgy route and to do a comparative analysis of the influence of this material when sintered in a muffle or in a microwave oven. The results showed that the doping of the niobium pentoxide with
Cerâmica. Publicado em: 2019-01
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7. Sample Preparation Applied to Analysis of Proteins in Cowpea Seeds (Vigna unguiculata (L.) Walp.)
In this study, 20 different protocols for protein extraction of cowpea seeds in natura were evaluated taking into account four parameters: cell disruption method, time, temperature and solvent. Factorial design experiments were executed to determine the effects on the total protein content of extracts. The total protein content was determined and the results
J. Braz. Chem. Soc.. Publicado em: 2019-01
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8. Study on Preparation and Performance of High Swelling Bentonite
ABSTRACT For improving the expansibility of natural Ca-based bentonite (Ca-Bent), the Ca-Bent was modified with sodium dodecyl benzene sulfonate(SDBS)-Na2CO3 complex agent by microwave semi-dry method. And the ratio of Na2CO3 to SDBS, microwave power, radiation time and initial temperature on the modification were studied. Furthermore, X-ray diffraction (XRD
Matéria (Rio J.). Publicado em: 18/10/2018
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9. Use of Mixture Design with Minimal Restrictions to Optimize an Extraction Procedure Employing Diluted Acids Assisted by Ultrasound and Microwave for Nutrient Element Determination in Vegetal Samples
In this work, it was developed an alternative analytical strategy for the preparation of vegetal samples extracted with diluted acids and assisted by ultrasound and microwave radiation for the determination of nutrients elements by fast sequential flame atomic absorption spectrometer. The conditions optimized using univariate and multivariate methodologies f
J. Braz. Chem. Soc.. Publicado em: 2018-06
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10. Design of Microwave Absorbers using Improvised Particle Swarm Optimization Algorithm
Abstract Particle Swarm Optimization (PSO) algorithm has been applied in electromagnetics to design microwave absorbers. Generally, microwave absorbers are used for absorbing the electromagnetic radiation caused due to numerous electronic equipments and is being extensively used in stealth technology. The main aim of this paper is to find and analyze the min
J. Microw. Optoelectron. Electromagn. Appl.. Publicado em: 2018-06
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11. Commercial and Noncommercial Peroxidases Activity under Ultrasound and Microwave Treatment: a Pretreatment to Improve Wastewater Treatment
This study aimed at evaluating the activity of peroxidases after ultrasound and microwave radiation exposure as an alternative to the wastewater treatment improvement. The results showed that after treatment with ultrasound using a power of 30% and a temperature of 55 °C was obtained an increase in relative activity, 129.5% in the enzyme from rice bran, 147
J. Braz. Chem. Soc.. Publicado em: 2017-10
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12. New Design of Mini PTFE Vessels for Sample Preparation in Micro Scale: Determination of Cd, K, Mg and Na in Biological Sample
This paper presents a study involving the development of a new mini polytetrafluoroethylene (PTFE) vessel project for biological sample preparation in micro scale in closed system with microwave radiation for subsequent determination of Cd, K, Mg and Na by atomic spectrometry techniques. All experiments were carried out in micro quantities of samples (up to
J. Braz. Chem. Soc.. Publicado em: 2017-10