Electron Spin Resonance Esr
Mostrando 13-24 de 48 artigos, teses e dissertações.
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13. Ligas amorfas de silicio e germanio hidrogenadas e materiais relacionados
Neste trabalho estudamos as ligas amorfas de silício e germânio hidrogenadas (a-SixGe1-x:H), o germânio amorfo hidrogenado (a-Ge:H), além do silício amorfo hidrogenado (a-Si:H). Apresentamos resultados nas propriedades estruturais e opto-eletrônicas de ligas crescidas por r.f. sputtering, ricas em germânio (x £ 0.25). Encontramos que para x £ 0.1 a
Publicado em: 1994
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14. Sintese, caracterização e algumas propriedades do oxido de tetanio (IV) enxertado sobre superficie de silica gel
The synthesis of titanium(IV) oxide on silica gel surface was carried out reacting the silanol groups of the silica gel surface with titanium tetrachloride, in organic solvent. The reproducibility of the method was very satisfactory for the different silicas, always resulting in an average quantity of titanium of 1.5 mmol g. The X-ray photoelectron spectrosc
Publicado em: 1993
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15. Aplicações da espectroscopia fotoacustica e ressonancia paramagnetica eletronica ao estudo de materiais cataliticos
Spectroscopic characterization of heterogeneous catalysts are investigated using both Electron Spin Resonance (ESR) and Photoacoustic (PAS) techniques. An ESR study of crystalline zeolitic chromosilicate and ironsilicate, as well its optical properties has been presented with the purpose of further characterization of the distribution of each Cr3+ and Fe3+ s
Publicado em: 1991
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16. Electron Spin Resonance Studies of Carbonic Anhydrase: Transition Metal Ions and Spin-Labeled Sulfonamides*
Electron spin resonance (esr) spectra of Cu(II) and Co(II) carbonic anhydrase, and a spin-labeled sulfonamide complex of the Zn(II) enzyme, are reported. The coordination geometry of Cu(II) bound in the enzyme appears to have approximately axial symmetry. Esr spectra of enzyme complexes with metal-binding anions also show axial symmetry and greater covalency
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17. Fluorescence quenching and electron spin resonance study of percolation in a two-phase lipid bilayer containing bacteriorhodopsin.
The effect of bacteriorhodopsin (BR) on the percolation properties of dimyristoylphosphatidylcholine/distearoylphosphatidylcholine bilayers was examined by studying the quenching of a lipid-bound fluorophore by a lipid-bound quencher, and by spin-spin interactions of a nitroxide-labeled lipid using electron spin resonance (ESR). At the low concentrations of
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18. Investigation of Very Slowly Tumbling Spin Labels by Nonlinear Spin Response Techniques: Theory and Experiment for Stationary Electron Electron Double Resonance
The investigation of very slowly tumbling spin labels by nonlinear electron spin response techniques is discussed. Such techniques permit characterization of rotational processes with correlation times from 10-3 to 10-7 sec even though the linear spin response (ESR) technique is insensitive to motion in this region. Nonlinear techniques fall into two categor
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19. ELECTRON SPIN RESONANCE OF AN IRRADIATED SINGLE CRYSTAL OF L-TYROSINE-HCL*
Analysis of the electron spin resonance (ESR) of a γ-irradiated single crystal of L-tyrosine-HCl reveals a free radical formed by loss of an H from the hydroxyl group attached to the ring. Principal g values of the radical are gx = 2.0023 ± 0.0005, gy = 2.0067 ± 0.0005, and gz = 2.0045 ± 0.0005, with gx perpendicular to the plane of the ring and gy along
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20. Electron Spin Resonance of Chlorophyll and the Origin of Signal I in Photosynthesis
A comparison has been made between Signal I, the photo-electron spin resonance signal associated with the primary light conversion act in photosynthesis, and free-radical signals generated in various chlorophyll species in vitro. The esr signals obtained from chlorophyll·monomer, (Chl·L)+., chlorophyll dimer, (Chl2)+., and chlorophyll oligomer, (Chl2)n+.,
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21. Iron supplementation generates hydroxyl radical in vivo. An ESR spin-trapping investigation.
Electron spin resonance (ESR) spectroscopy has been used to investigate hydroxyl radical generation in rats with chronic dietary iron loading. A secondary radical spin-trapping technique was used where hydroxyl radical forms methyl radical upon reaction with DMSO. The methyl radical was then detected by ESR spectroscopy as its adduct with the spin trap alpha
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22. A single-residue deletion alters the lipid selectivity of a K+ channel-associated peptide in the beta-conformation: spin label electron spin resonance studies.
Lipid-peptide interactions with the 27-residue peptide of sequence KLEALYILMVLGFFGFFTLGIMLSYIR reconstituted as beta-sheet assemblies in dimyristoylphosphatidylcholine bilayers have been studied by electron spin resonance (ESR) spectroscopy with spin-labeled lipids. The peptide corresponds to residues 42-68 of the IsK voltage-gated K+ channel protein and con
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23. Lipid-gramicidin interactions using two-dimensional Fourier-transform electron spin resonance.
The application of two-dimensional Fourier-transform electron-spin-resonance (2D-FT-ESR) to the study of lipid/gramicidin A (GA) interactions is reported. It is shown that 2D-FT-ESR spectra provide substantially enhanced spectral resolution to changes in the dynamics and ordering of the bulk lipids (as compared with cw-ESR spectra), that result from addition
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24. Evidence that an iron-nickel-carbon complex is formed by reaction of CO with the CO dehydrogenase from Clostridium thermoaceticum.
The interaction between carbon monoxide and the CO dehydrogenase from Clostridium thermoaceticum was studied by electron spin resonance (ESR) techniques. When the enzyme reacts with CO, a paramagnetic complex is formed which previously was shown, by isotope substitution, to be due to a nickel-carbon species. In this paper, we demonstrate that iron is also a