Absorption Spectra
Mostrando 1-12 de 728 artigos, teses e dissertações.
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1. VIBRATION CHARACTERISTICS, CHEMICAL BONDS AND WEAK INTERACTIONS OF 4- AND 5-HYDROXYSALICYLIC ACID INVESTIGATED BY TERAHERTZ SPECTROSCOPY AND DENSITY FUNCTIONAL THEORY
The terahertz (THz) absorption spectra of 4- and 5-hydroxysalicylic acid were measured by terahertz time-domain spectroscopy (THz-TDS) in the range of 0.4-2.8 THz. The unit cells of both were calculated by density functional theory (DFT), and the theoretical simulation and experimental data were basically in agreement. To further interpret the origin of the
Química Nova. Publicado em: 2022
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2. DESENVOLVIMENTO DE ACESSÓRIO PORTÁTIL DE CONTROLE DE TEMPERATURA PARA MEDIDAS ESPECTROSCÓPICAS
Temperature is a natural phenomenon that may modify the structure of chemical compounds and hence their properties. We aimed to develop a simple portable system based on the Peltier principle for spectral characterization of compounds with temperature-dependent structure. The device was constructed and adapted to three pieces of equipment: X-ray diffractomet
Química Nova. Publicado em: 2022
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3. Spectrofluorimetric Determination of Hydrochlorothiazide by a Carbon Dots-Based Probe via Inner Filtering Effect and Resonance Rayleigh Scattering
Synthesis of carbon dots (CDs) from natural resources not only enables green synthesis and production of environmentally friendly materials, but also provides a cost-effective probe as a fluorescence nanosensor. The proposed sensor introduces a unique one-pot hydrothermal CDs synthesis from alfalfa leaves, which is promising for sensing hydrochlorothiazide (
Journal of the Brazilian Chemical Society. Publicado em: 2022
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4. Study of structural, optical, and morphological characteristics of manganese titanate (MnTiO3) obtained by combustion reaction using microwave energy
Abstract MnTiO3 is a semiconductor that has relevant dielectric and optical properties. For the synthesis of manganese titanate (MnTiO3) powders, the combustion method via microwave and subsequent calcination at 500, 700, and 900 °C were used. The structural, morphological, and optical properties of the samples were investigated. X-ray diffraction analyzes
Cerâmica. Publicado em: 2021-03
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5. INCORPORAÇÃO DE RODAMINA B EM MEMBRANA DE POLIAMIDA PELO MÉTODO DA ADSORÇÃO
We have incorporated rhodamine into polyamide membranes by additive manufacture selective laser sintering technology. Incorporation into 0.5 cm2 membranes was conducted at different pH values and constant temperature of 25 oC. The amounts of incorporated dye were determined by a calibration curve, and analyses showed rhodamine incorporation in the order of 1
Quím. Nova. Publicado em: 2021-02
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6. CURCUMINA COMO INDICADOR NATURAL DE PH: UMA ABORDAGEM TEÓRICA-EXPERIMENTAL PARA O ENSINO DE QUÍMICA
This paper proposes the development of a simple experiment with easily accessible and low cost materials, enabling its practice with or without laboratory infrastructure, with feasibility for computational theoretical study. On the other hand, the objective of the work is to develop a chemical experiment that demonstrates that the chromophore curcumin (natur
Quím. Nova. Publicado em: 2021-02
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7. Blue Glow Sticks: Cinnamic Acids and Arylacrylonitriles with Liquid-Crystalline Properties and Highly Fluorescent
Five new π-conjugated chromophores derived from acrylic acid and acrylonitrile were synthesized and their thermal and photophysical behaviors were analyzed. They were designed and synthesized through Knoevenagel condensations between arylacetylenebenzaldehydes and a methylene group activated from cyanoacetic and malonic acids. The characterization of the ta
J. Braz. Chem. Soc.. Publicado em: 2021-01
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8. 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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9. A Symmetrical Dirhenium(I) Complex with 4,4’’-Azobis(2,2’-bipyridine) as a Bridging Ligand: Synthesis, Physicochemical Properties and Applications in Detection of Biologically Relevant Thiols and in Chemotherapy for Bone Cancer
A new dinuclear complex of formula [{Re(CO)3(py)}2(µ-4,4”-azobpy)](PF6)2, with py = pyridine and 4,4”-azobpy = 4,4”-azobis(2,2’-bipyridine), has been synthesized and characterized by spectroscopic and electrochemical techniques. The symmetrical nature of the dimetallic cation has been confirmed by nuclear magnetic resonance (NMR) measurements. When
J. Braz. Chem. Soc.. Publicado em: 2020-11
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10. Blue-Emitting MWO4:Tm3+ (M: Sr, Ba) Phosphors Prepared by Coprecipitation Method at Room Temperature
MWO4 host matrices (M: Sr, Ba) doped with different Tm3+ concentrations (0.02, 0.04, 0.06, 0.08 and 0.10 mol%) have been successfully prepared by the coprecipitation method at room temperature. The as-prepared nanophosphors were characterized by infrared spectroscopy showing intense absorption bands in the range of 700-1000 cm-1 attributed to the symmetrical
J. Braz. Chem. Soc.. Publicado em: 2020-11
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11. Synthesis, Characterization, Absorption and Fastness Properties of Novel Monoazo Dyes Derived from 1-Phenyl-3-amino-4-(2-thiazolilazo)pyrazol-5-one
Monosubstitute thiazolyl amines were diazotized in acetic acid, coupled to 1-phenyl-3-aminopyrazol-5-one (1a-1c) and acetylated to obtain the 2a-2c dyes. The dyes were characterized by elemental analysis and spectroscopic (Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), ultraviolet (UV)) methods. The effects on the visible absorption spe
J. Braz. Chem. Soc.. Publicado em: 2020-09
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12. Characterization of hydrolysates of collagen from mechanically separated chicken meat residue
Abstract Obtaining collagen and hydrolysates from mechanically separated chicken meat residue is an excellent way to add value to this waste. The aims of this study were to obtain collagen hydrolysates from chicken MSM residue using Alcalase® and Flavourzyme® enzymes, as well characterizing the functional, structural and thermal stability properties. The h
Food Sci. Technol. Publicado em: 2020-06