Absorption Coefficient
Mostrando 1-12 de 188 artigos, teses e dissertações.
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1. Atomic Absorption Spectrometry as an Alternative to Determine the Presence of Gold Nanoparticles on or in Silica Matrix
Two different gold-silica-based nanomaterials were prepared: (i) silica-supported gold nanoparticles (AuNP/SiO2); and (ii) gold-silica core-shell nanoparticles (AuNP@SiO2). Three strategies for sample treatment (S), consisting in acid treatments, were employed: (S1) HNO3; (S2) HNO3 + HCl; and (S3) HF + HNO3 + HCl, applying microwave oven digestion for S2 and
Journal of the Brazilian Chemical Society. Publicado em: 2022
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2. DETERMINAÇÃO DA AUTENTICIDADE DE AMOSTRAS DE AZEITE COMERCIAIS APREENDIDAS NO ESTADO DO ESPÍRITO SANTO USANDO UM ESPECTROFOTÔMETRO PORTÁTIL NA REGIÃO DO NIR
Many instrumental techniques are used to monitor the quality of food products, highlighting near infrared spectroscopy (NIRS). In order to determine the authenticity of 60 commercial oil samples seized by the Espírito Santo state police, this work used a portable spectrometer in the NIR region associated with chemometric tools such as principal component an
Quím. Nova. Publicado em: 20/07/2020
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3. Voltammetric Determination of Free and Total Manganese in Tea Infusions
Tea infusions are a source of mineral nutrients, including manganese. Although it is classified as an essential element, the excess of manganese is toxic for humans and its toxicity depends on its bioavailability. In this context, we propose a simple procedure to determine free and total manganese in black tea infusions by square-wave voltammetry (SWV). Free
J. Braz. Chem. Soc.. Publicado em: 2020-07
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4. An Alternative Spectrophotometric Determination of Carbaryl Insecticide Residues in Water Samples Using the Cerium-Catalyzed Belousov-Zhabotinsky Oscillating Reaction
An alternative approach for carbaryl determination based on the change in the oscillation period of the Belousov-Zhabotinsky (BZ) reaction under the addition of carbaryl is demonstrated. The oscillations were observed by spectrophotometric measurement at 320 nm, corresponding to the maximum absorption wavelength of cerium(IV) catalyst. The oscillation period
J. Braz. Chem. Soc.. Publicado em: 2020-05
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5. Evaluation of a Metal-Organic Composite (Tungsten-Lignin) for Attenuation of Gamma Radiation
The objective of this work was to use tungsten and lignin as precursors to obtain a metal-organic composite tungsten-lignin (W-Lig) using different sintering temperatures. Tungsten is a refractory metal and it was selected for the composite since it is widely used for high-energy radiation shielding as it has an excellent absorption cross section for thermal
Mat. Res.. Publicado em: 02/09/2019
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6. Semiconductor Nanocrystals-Reduced Graphene Composites for the Electrochemical Detection of Carbendazim
A new nanocomposite based on ZnCdTe semiconductor nanocrystals (NCs) synthesized in situ on reduced graphene oxide (rGO) was obtained. The heterostructure was characterized using UV-Vis emission and absorption spectroscopies, which provided evidences of the growth of the nanocrystals onto the rGO matrix. To evaluate the electrochemical performance, carbon pa
J. Braz. Chem. Soc.. Publicado em: 23/05/2019
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7. Synthesis of Hydrotalcite-Supported CdTe Semiconductor Nanocrystals for Electrochemical Detection of Ciprofloxacin
In this work, CdTe quantum dots (QDs) were controllably grown onto the surface of layered double hydroxide (LDH) aiming to develop a sensitive and selective method for the electrochemical detection of ciprofloxacin (CPX). Emission and absorption spectroscopy results as well as high-resolution transmission electron microscopy (HRTEM) images evidenced the form
J. Braz. Chem. Soc.. Publicado em: 23/05/2019
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8. Availability of betaine present in fine wheat bran in diets for growing pigs
ABSTRACT The objective of this paper was to investigate the availability of betaine present in fine wheat bran (FWB) in diets for growing pigs. We used thirty crossbred intact males, housed individually in metabolic cages and distributed in a randomized block design, with five treatments and six replicates. Blocks consisted of two periods of 15 days. Average
R. Bras. Zootec.. Publicado em: 04/02/2019
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9. Determinación de bajas concentraciones de hidrógeno en aleaciones de circonio utilizando radiografía de neutrones como técnica no destructiva
ABSTRACT Zircon base alloys (Zr) are used in the manufacture of fuel sheaths and structural components of power reactors because of their low neutron absorption. These alloys are susceptible to damage by hydrogen (H) because the concentration of the alloys can be increased locally in response to temperature or stress gradients. This causes a general degradat
Matéria (Rio J.). Publicado em: 19/07/2018
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10. Theoretical Approach to Simulate Efficient Selective Solar Absorbers With Micro or Nano Structured Arrays
Study of the solar absorber with photonic crystal or micro structures as the heat absorbing surfaces operated at a high-temperature was conducted. Numerical calculations based on rigorous coupled-wave analysis were performed to determine the absorptance of the photonic crystal surface on the absorber. The effect of nano geometry of the photonic crystal in tu
Mat. Res.. Publicado em: 22/03/2018
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11. CÉLULAS SOLARES DE PEROVSKITAS: UMA NOVA TECNOLOGIA EMERGENTE
Solar energy has been considered as an important source of clean and safe energy to overcome the problems associate to the burn of fossil fuels (e.g. climate changes, pollution, health problems, etc.). In the area of photovoltaics, devices that convert solar energy into electricity, perovskites solar cells (PSC) have attracted great attention due to their ra
Quím. Nova. Publicado em: 2018-01
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12. Copper Cobalt Magnetic Ceramic Materials Characterization at Terahertz Frequencies
ABSTRACT: This study presents the complex index of refraction and the complex permittivity of a magnetic ceramic material made of copper, cobalt, and iron oxides. The index of refraction and the extinction coefficient of the CuCo-ferrite exhibit an almost frequency independent behavior and were averaged to n = 3.62 ± 0.05 and k = 0.06 ± 0.02, respectively,
J. Aerosp. Technol. Manag.. Publicado em: 2017-06