Size Spectra
Mostrando 1-12 de 186 artigos, teses e dissertações.
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1. X-ray line profile analysis and magnetic and optical properties of FexZn0.95-xCr0.05O nanoparticles fabricated by sol-gel route
Abstract FexZn0.95-xCr0.05O nanoparticles have been obtained for the different concentrations of Fe ions by using the sol-gel method. The hexagonal wurtzite structure of all the samples was confirmed by Rietveld refined X-ray diffraction patterns. The addition of Fe ions decreased lattice constants a and c from 3.2487 to 3.2474 Å and 5.2043 to 5.2029 Å, re
Cerâmica. Publicado em: 2022
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2. Design, Synthesis, and Application of Colored Cobalt Pigments (Pink, Blue, Green)
The combination of white or colorless oxides (MgO, Al2O3, ZnO) with colorant ions (Co2+) generates colored pigments (pink, blue, green). The color is caused by the insertion of the colorant ion in the respective crystal lattices (periclase, alumina, wurtzite), as verified by X-ray diffraction. Absorption spectra in the visible region show analogous triplet b
J. Braz. Chem. Soc.. Publicado em: 2020-11
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3. ASPECTOS ESTRUTURAIS DE ESFERAS DE QUITOSANA/PVA RETICULADAS COM GLUTARALDEÍDO SUBMETIDAS A DIFERENTES TRATAMENTOS TÉRMICOS
Chitosan is a biopolymer derived from chitin and the most abundant polysaccharide in nature after cellulose. This biopolymer has been applied in different areas due its biodegradability and biocompatibility properties. Modifications of chitosan structure by cross-linking chemical agents can alter its physical, chemical, and morphological characteristics. The
Quím. Nova. Publicado em: 2020-09
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4. ANÁLISE ESPECTROSCÓPICA DA MATÉRIA ORGÂNICA NO SEDIMENTO SUPERFICIAL DA BAÍA DE SEPETIBA, RIO DE JANEIRO, BRASIL
Spectroscopic techniques are powerful tools for molecular organic matter assessment in sediments, which analysis request low sample mass and are cheap, fast and easy to obtain. The aim of this work was to evaluate the elemental (C, N) and molecular composition of the organic matter in relation to the grain-size distribution over surface sediments from Sepeti
Quím. Nova. Publicado em: 2020-05
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5. Residue-Based CaO Heterogeneous Catalysts from Crab and Mollusk Shells for FAME Production Via Transesterification
The production of fatty acid methyl esther (FAME) via transesterification was studied, assessing the influence of CaO heterogeneous catalysts obtained from four different fishery residues: sururu, crab, clam and mussel. Characterization and properties of the residues were obtained via thermogravimetric analysis, X-ray diffraction, X-ray fluorescence, Fourier
J. Braz. Chem. Soc.. Publicado em: 2020-04
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6. Synthesis and characterization of mesoporous materials with SBA and MCM structure types
Resumo Materiais mesoporosos são estruturas promissoras para aplicação em catálise e adsorção devido à elevada área superficial e grande tamanho dos poros. Materiais mesoporosos foram sintetizados pelo método hidrotérmico com novos surfactantes, distintos daqueles observados na literatura, a fim de realizar um estudo de sua estrutura e obter materi
Cerâmica. Publicado em: 14/11/2019
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7. Influence of Particles Size on NIR Spectroscopic Estimations of Charcoal Properties
ABSTRACT The objective of this study was to evaluate the influence of particle size of charcoal samples on the predictive model statistics of charcoal chemical composition based on the NIR spectroscopy. Spectra of Acacia and of Eucalyptus charcoal were collected in the 100, 60 and 40 mesh granulometry, besides the powder remaining at the bottom of the sieves
Floresta Ambient.. Publicado em: 09/09/2019
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8. Hydrothermal Synthesis to Water-stable Luminescent Carbon Dots from Acerola Fruit for Photoluminescent Composites Preparation and its Application as Sensors
Carbon dots (C-dots) possess the attractive properties of high stability, low toxicity, good water solubility, simple synthetic routes as well as size and excitation-dependent photoluminescence (PL).The aim of this work was to synthesize photoluminescent C-dots by hydrothermal method using acerola fruit (Malpighiaemarginata) as a row material, since this fru
Mat. Res.. Publicado em: 06/06/2019
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9. 1H NMR STUDY OF THE HOST-GUEST CHEMISTRY IN A SUPRAMOLECULAR HELICATE FEII 2L3 SOLUTION
A novel [FeII2L3]4+ metallo-organic helicate results from subcomponent self-assembly of a C3-symmetric triamine (4,4',4''- (1,3,5-triazine-2,4,6-triyl) trianiline), octahedral iron(II) and 2-formyl pyridine in CH3CN solution. The constitution of this supramolecular helicate was confirmed by ESI-MS and 1H NMR spectra. Different planar aromatic guests were sel
Quím. Nova. Publicado em: 27/05/2019
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10. Changes in the crystalline degree in neutron irradiated EPDM viewed through infrared spectroscopy and inelastic neutron scattering
ABSTRACT The changes in the degree of crystallinity in commercial Ethylene Propylene Diene rubber-type M (EPDM) irradiated with neutrons at different doses has been studied by means of inelastic neutron scattering and infrared absorption spectroscopy experiments. EPDM samples were taken from the housing of non-ceramic electrical insulators which are used in
Matéria (Rio J.). Publicado em: 19/07/2018
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11. Structural, Thermal, Optical, and Photoacoustic Study of Mechanically Alloyed Nanocrystalline SnTe
A nanostructured SnTe phase was produced by mechanical alloying after 2 h of milling. Part of the as-milled powder was annealed and its X-ray diffraction (XRD) pattern was recorded. The XRD patterns of the as-milled and annealed samples were refined using the Rietveld method. After annealing, partial decomposition of the SnTe phase was observed and corrobora
Mat. Res.. Publicado em: 07/06/2018
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12. Optical and Structural Study of ZnO Thin Films Deposited by RF Magnetron Sputtering at Different Thicknesses: a Comparison with Single Crystal
Optical characterizations of preferred orientation (002) ZnO thin films, prepared by RF magnetron sputtering under pure argon plasma, with different thicknesses have been investigated, where grain size and resistivity increase with thickness. Energy band gap and refractive indices have been calculated. A correlation between band gap values and crystalline qu
Mat. Res.. Publicado em: 16/04/2018