Electron Paramagnetic Resonance
Mostrando 1-12 de 441 artigos, teses e dissertações.
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1. Thermostimulated crystal structure transformation of the polymineral clay submicron particles
Abstract Changes in the structure of phyllosilicate microparticles of submicron fractions of polymineral clay with an average size of 290 nm, as well as changes in the positions of impurity ions of transition metals in the crystal lattice, were studied by X-ray diffraction analysis, Fourier transform infrared spectroscopy, and high-resolution electron parama
Cerâmica. Publicado em: 2022
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2. Intercalation of Apocarotenoids from Annatto (Bixa orellana L.) into Layered Double Hydroxides
Synthetic conditions were evaluated to intercalate norbixin into layered double hydroxides (LDH). Norbixin was isolated from a hydrosoluble commercial annatto extract. LDH samples comprising M2+/Al3+ (M = Mg, Zn) were synthesized by coprecipitation and characterized by X-ray diffraction, thermal analysis coupled to mass spectrometry, vibrational spectroscopi
J. Braz. Chem. Soc.. Publicado em: 2020-11
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3. Synthesis, Antileishmanial Activity and Spin Labeling EPR Studies of Novel β-Carboline-Oxazoline and β-Carboline-Dihydrooxazine Derivatives
A series of novel 1-(substituted-phenyl)-3-(4,5-dihydro-1,3-oxazol-2-yl)-9H-β-carboline (8a-8i) and 1-(substituted-phenyl)-3-(5,6-dihydro-4H-1,3-oxazin-2-yl)-9H-β-carboline (9a-9h) derivatives, as well as their respective N-(chloroalkyl)-1-(substituted-phenyl)-9H-β-carboline-3-carboxamide precursors (6a-6i and 7a-7h), were synthesized and evaluated for th
J. Braz. Chem. Soc.. Publicado em: 2020-06
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4. Cr3+ Doped Al2O3 Obtained by Non-Hydrolytic Sol-Gel Methodology
This paper reports the synthesis and characterization of Cr3+-doped alumina by the sol-gel non-hydrolytic methodology. The resulting sample was treated at different temperatures. X-ray diffraction revealed that the ruby phase emerged in the sample treated at 1100 ºC, which was later confirmed by absorption bands correspondent to Cr3+ ions allowed transition
J. Braz. Chem. Soc.. Publicado em: 2019-04
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5. Copper(II) Nitroaromatic Schiff Base Complexes: Synthesis, Biological Activity and Their Interaction with DNA and Albumins
Copper(II) complexes of the Schiff base ligands 2-((5-nitrofuran-2-yl)methyleneamino)phenol (HL1) and 2-(4-nitrobenzylideneamino)phenol (HL2) were prepared and characterized using physicochemical and spectroscopic techniques. In these complexes the Schiff base ligands acted as a bidentate donor bound to Cu2+ through the oxygen and nitrogen atoms in the depro
J. Braz. Chem. Soc.. Publicado em: 2017-01
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6. EPR and Optical Absorption Studies of Cu2+ in Boro-Arsenate Glasses
Electron paramagnetic resonance (EPR) and optical absorption studies of xMgO- (25-x) Li2O-50B2O3-25As2O3 glasses were made by introducing Cu2+ as a spin probe. The EPR spectra of all the glass samples recorded at X-band frequencies have similar spectral features. The Cu2+ ions are in well-defined axial sites, but subjected to small distortion leading to the
Mat. Res.. Publicado em: 01/12/2016
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7. Dating stalagmite from Caverna do Diabo (Devil´S Cave) by TL and EPR techniques
ABSTRACT A cylindrical fragment of stalagmite from Caverna do Diabo, State of São Paulo, Brazil, has been studied and dated by thermoluminescence and electron paramagnetic resonance techniques. The thermoluminescence glow curves of stalagmite samples and subsequently gamma irradiated, have shown rise of three peaks at 135, 180 and 265 °C. From electron par
An. Acad. Bras. Ciênc.. Publicado em: 2016-12
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8. Structural, Thermal and Optical Properties of Pure and Mn2+ Doped Poly(Vinyl Chloride) Films
Pure and Mn2+ doped poly(vinyl chloride) (PVC) polymer films were prepared using the solution cast technique. The prepared samples have been characterized by X-ray diffraction (XRD), UV-Vis Spectroscopy (UV-Vis), Fourier transform infrared (FTIR) Spectroscopy, Thermogravimetric analysis (TGA), Differential Scanning Calorimetry (DSC), Electron Paramagnetic Re
Mat. Res.. Publicado em: 19/09/2016
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9. The Influence of a Translucent Fiberglass Post on the Polymerization of Dual Cure Resin Cement Analyzed by Electron Paramagnetic Resonance
AbstractElectron Paramagnetic Resonance (EPR) was used as an alternative method to study the conversion degree of dual cure resin cement and verify the influence of prefabricated translucent fiberglass post on the dual cure resin cement polymerization at different restoration points. The post cementation of White Post DC (FGM, Joinville, SC, Brasil) was simu
Mat. Res.. Publicado em: 2015-10
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10. Antioxidant effect of 4-nerolidylcatechol and α-tocopherol in erythrocyte ghost membranes and phospholipid bilayers
4-Nerolidylcatechol (4-NC) is found in Pothomorphe umbellataroot extracts and is reported to have a topical protective effect against UVB radiation-induced skin damage, toxicity in melanoma cell lines, and antimalarial activity. We report a comparative study of the antioxidant activity of 4-NC and α-tocopherol against lipid peroxidation initiated by two fre
Braz J Med Biol Res. Publicado em: 06/09/2013
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11. Electron paramagnetic resonance (EPR) spectral components of spin-labeled lipids in saturated phospholipid bilayers: effect of cholesterol
Electron paramagnetic resonance (EPR) spectroscopy was used to study the main structural accommodations of spin labels in bilayers of saturated phosphatidylcholines with acyl chain lengths ranging from 16 to 22 carbon atoms. EPR spectra allowed the identification of two distinct spectral components in thermodynamic equilibrium at temperatures below and above
Quím. Nova. Publicado em: 2013
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12. Caracterização de espécies paramagnéticas em sementes por ressonância paramagnética eletrônica
Paramagnetic species were characterized in the seeds of radish wild, rice, mustard, wheat, oats, sorghum, sunflower, soybean, cotton, beans, maize and barley by EPR (Electron Paramagnetic Resonance). Some paramagnetic species present in the soil were also investigated, such as goethite, hematite, magnetite, and ferrihydrite. EPR experiments were performed at
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 01/03/2012