Ultraviolet Emission
Mostrando 1-12 de 50 artigos, teses e dissertações.
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1. A novel fluorescence sensor for the detection of chloride ion in artificial sweat and environmental water with nitrogen-doped graphene quantum dots
A new fluorescent detection route for chloride ion was designed with Nitrogen-doped graphene quantum dots (N-GQDs), which were prepared by a traditional hydrothermal method with citric acid as carbon source and urea as nitrogen source. The prepared N-GQDs solution was light yellow, and the freeze-dried solid was black. It emitted blue light under ultraviolet
Química Nova. Publicado em: 2022
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2. Preparation of Fluorescent Carbon-Based Dots from Waste Tire Pyrolysis
The pyrolysis of waste tire has been proposed as an alternative route to its recycling producing residual oils that can be used as fuels. In this work, a physicochemical process to obtain carbon-based dots (CBD) from carbon black (CBL) derivatives of tires is described. For this, the CBL was treated with different acids to produce CBL1 and CBL2 particles sus
J. Braz. Chem. Soc.. Publicado em: 2020-11
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3. Synthesis, Characterization, and Photocatalytic Properties of Flower-like Mn-doped Ceria
Mn-doped CeO2 flower-like microstructures have been synthesized by a facile one-step composite-hydroxide-mediated method. The structure, morphology, optical and the surface properties of Mn doped CeO2 have been investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), UV-Vis absorption spectroscopy and X-ray photoelectron
Mat. Res.. Publicado em: 16/07/2018
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4. Effect of Different Synthesis Methods on the Textural Properties of Calcium Tungstate (CaWO4) and Its Catalytic Properties in the Toluene Oxidation
Calcium tungstate (CaWO4) crystals were prepared by microwave-assisted hydrothermal (MAH) and polymeric precursor methods (PPM). These crystals were structurally characterized by X-ray diffraction (XRD), N2 adsorption, X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) measurements. The morphology and size of
Mat. Res.. Publicado em: 16/04/2018
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5. Synthesis and Photophysical Characterization of Proton Transfer-Based Thiourea Derivatives: Potential Application as Colorimetric Naked-Eye Chemosensor for Fluoride Detection in Solution
Two new thiourea derivatives were synthesized through the reaction of photoactive aminohydroxybenzazoles and p-isothiocyanate benzoic acid via nucleophilic addition reaction. The compounds were characterized using high resolution mass spectrometry with eletrospray ionization (HRMS-ESI), Fourier transform infrared (FTIR), 13C and 1H nuclear magnetic resonance
J. Braz. Chem. Soc.. Publicado em: 2017-09
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6. Synthesis and Characterization of Nb2O5:La3+,Eu3+ Phosphors Obtained by the Non-Hydrolytic Sol-Gel Process
The phosphor-converted light-emitting diode technique is an important solid-state illumination strategy. Sulfide-based materials are the most often employed red phosphors, but they are chemically unstable and present lower efficiency in comparison to the blue and green phosphors. Therefore, it is important to find a new red phosphor source that can emit inte
J. Braz. Chem. Soc.. Publicado em: 2015-12
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7. NIR Luminescence from Sol-Gel Er3+ Doped SiO2:GeO2 Transparent Gels, Nanostructured Powders and Thin Films for Photonic Applications
Samples of (1 – x)SiO2:xGeO2 compositions, containing x = 10 and 20, and doped with Er3+, were prepared by a simple sol-gel route. Homogeneous and transparent gels were synthesized and xerogels were obtained by gel annealing from 700 ºC to 1100 ºC. Films exhibiting high transmittance in the visible and near infrared were deposited by spin-coating techniq
J. Braz. Chem. Soc.. Publicado em: 2015-12
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8. Ultraviolet radiation emitted by lamps, TVs, tablets and computers: are there risks for the population?
AbstractThe frequent human exposure to various types of indoor lamps, as well as other light sources (television monitors, tablets and computers), raises a question: are there risks for the population? In the present study the emission of UVA and UVB radiation by lamps and screens of electronic devices were measured in order to determine the safe distance be
An. Bras. Dermatol.. Publicado em: 2015-08
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9. Electrospinning Preparation and Photoluminescence Properties of Y3Al5O12:Eu3+ Nanobelts
Novel structures of Y3Al5O12: Eu3+ (denoted as YAG: Eu3+ for short) nanobelts were fabricated by calcination of the electrospun PVP/[Y(NO3)3+Eu(NO3)3+Al(NO3)3] composite nanobelts. X-ray powder diffraction (XRD) analysis showed that YAG: Eu3+ nanobelts were cubic in structure with space group Ia3d. Fourier transform infrared spectroscopy (FTIR) analysis mani
Mat. Res.. Publicado em: 2015-04
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10. Effects of precursor concentration and reaction time on sonochemically synthesized ZnO nanoparticles
The sonochemical reaction between Zn(NO3)2 and hexamethylenetetramine (HMT) resulted in different products depending on amounts of Zn(II) cations in the aqueous solution. Crystalline phase pure ZnO nanoparticles were obtained by using 0.05 M Zn(NO3)2-HMT. This single phase was formed by low power sonication for 20 min in an ultrasonic bath at ambient conditi
Mat. Res.. Publicado em: 03/12/2013
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11. Photo-Induced conductivity of heterojunction GaAs/Rare-Earth doped SnO2
Rare-earth doped (Eu3+ or Ce3+) thin layers of tin dioxide (SnO2) are deposited by the sol-gel-dip-coating technique, along with gallium arsenide (GaAs) films, deposited by the resistive evaporation technique. The as-built heterojunction has potential application in optoelectronic devices, because it may combine the emission from the rare-earth-doped transpa
Mat. Res.. Publicado em: 23/04/2013
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12. Espectroscopia ultrarrápida do polímero semicondutor luminescente MEH-PPV com excitação no ultravioleta / Ultrafast spectroscopy of the luminescent semiconducting polymer MEH-PPV with ultraviolet excitation
The optoelectronics industry is currently undergoing a transition period in which inorganic materials are being replaced by organic materials, oligomers and polymers, in the fabrication of some types of devices. However, factors such as low efficiency and low lifetime prevent polymer based devices on entering the market definitely. The solution of these issu
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 17/08/2012