Linear Absorption Coefficient
Mostrando 1-12 de 33 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. 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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3. 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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4. 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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5. 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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6. Partitioning of the diffuse attenuation coefficient for photosynthetically available irradiance in a deep dendritic tropical lake
ABSTRACT We studied the effects of particulate and dissolved optically active components on the attenuation of photosynthetic active radiation (PAR) in a tropical lake. The temporal and spatial distribution of tripton, Chl-a and aCDOM(440) and their relative contribution to the diffuse PAR attenuation coefficient (Kd) was investigated at 21 sites (dry and we
An. Acad. Bras. Ciênc.. Publicado em: 2017-05
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7. Decanoic Acid Reverse Micelle-Based Coacervates for Microextraction of Silver in Natural Waters Prior to Flame Atomic Absorption Spectrometry Determination
In the present work, a novel, simple, and efficient method for the determination of silver in natural water samples was developed. The method is based on the extraction of silver with coacervate made up of decanoic acid reverse micelles and the subsequent determination by flame atomic absorption spectrometry (FAAS). Dithizone was used as a chelating agent. T
J. Braz. Chem. Soc.. Publicado em: 2016-11
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8. Magnetic Nanoparticles Coated with Ionic Liquid as a Sorbent for Solid Phase Extraction of Chromium(VI) Prior to Its Determination by Electrothermal Atomic Absorption Spectrometry
A simple, sensitive and reliable method for the separation, preconcentration and determination of ultra trace amounts of chromium species has been developed. Chromium(VI) in aqueous sample was reacted with 9-phenyl-2,3,7-trihydroxy-6-fluorone to produce a chelate at pH of 5.0 and extracted onto the magnetic nanoparticles coated with the ionic liquid 1-hexade
J. Braz. Chem. Soc.. Publicado em: 2016-01
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9. Application of ftir in the determination of acrylate content in poly(sodium acrylate-co-acrylamide) superabsorbent hydrogels
Hydrogels have been prepared by free-radical solution copolymerization of acrylamide and sodium acrylate (NaAc), with molar ratio ranging from 25/75 to 80/20, respectively, using methylene bisacrylamide as the crosslinking agent. A FTIR spectroscopy procedure to determine the acrylate/acrylamide ratio in these hydrogels was proposed based on absorbance at 14
Química Nova. Publicado em: 2012
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10. Correlação in vitro in vivo para formas farmacêuticas sólidas de liberação modificada contendo diclofenaco de sódio / In vitro-in vivo correlation for sodium diclofenac modified release tablet formulations
The term in vitro-in vivo correlation (IVIVC) refers to the establishment of a rational relationship between the biological properties, or a parameter derived from a biological property produced by a dosage form, and a physicochemical characteristic or property of the same dosage form. The establishment of IVIVC enables the substitution of in vivo studies fo
Publicado em: 2009
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11. SÃntese e caracterizaÃÃo de nanopartÃculas de nÃquel para Ãptica nÃo linear / SÃntese e caracterizaÃÃo de nanopartÃculas de nÃquel para Ãptica nÃo linear
In this work, we describe the synthesis of nickel nanoparticles (NPs) stabilized using poly (vinyl pyrrolidone), their structural and optical (linear and nonlinear) characterization. In Chapter 1 we present a general introduction describing the work performed. In Chapter 2 it is presented a review of nickel NPsâ properties and some synthesis processes. In C
Publicado em: 2008
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12. Espectroscopia Ãptica nÃo linear de vidros especiais e colÃides
Nonlinear optical properties of special glasses and colloids were studied using the zscan technique. This technique aalows to calculate the nonlinear refraction index and the nonlinear absorption coefficient using the self-focusing or defocusing effect that appears when the incident laser pass through a nonlinear medium. Orthophosphate and polyphosphate anti
Publicado em: 2008