Ultraviolet Excitation
Mostrando 13-24 de 40 artigos, teses e dissertações.
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13. Aplicações de técnicas espectroscópicas e polarográficas para caracterização e avaliação da reatividade do húmus com o herbicida atrazina. / Application of spectroscopic and polarographic methods to characterize and evaluate the reactivity between humus and atrazine.
One alternative to disposal of urban residues is recycling through composts and earthworm composts (humus production). The absence of a quality standard of these materials however brings limitations to commercial development with damage to producers and consumers. In this work was proposed a strategic parameter to be used as standard. From Electron Paramagne
Publicado em: 1999
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14. Influence of rare earths on the properties and catalytic activity of the Y / Influência de terras raras nas propriedades e atividade catalitica da zeólita Y
The Y zeolites containing calcium and rare earth polivalent cations, RE,Ca/NaY (RE = La, Ce, Nd, Eu, Gd), were prepared by ion exchange, refluxing the NaY zeolite (Si/Al = 2,4) with calcium chloride and rare earth chloride solutions, followed by thermal treatment under nitrogen flow. The trivalent hydrated rare earth ions undergo hydrolysis, forming [RE.OH]2
Publicado em: 1992
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15. Absorption and Fluorescence of Water-Soluble Pigments Produced by Four Species of Pseudomonas
Pigments produced by four species of Pseudomonas during growth in three media were examined for visible and ultraviolet absorption. Ultraviolet fluorescence excitation and emission spectra were obtained. In all pigments, an absorption maximum occurs at 405 mμ. Ultraviolet excitation of fluorescence occurs primarily at 400 to 410 mμ, with smaller maxima at
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16. International Ultraviolet Explorer satellite observations of seven high-excitation planetary nebulae
Observations of seven high-excitation planetary nebulae secured with the International Ultraviolet Explorer (IUE) satellite were combined with extensive ground-based data to obtain electron densities, gas kinetic temperatures, and ionic concentrations. We then employed a network of theoretical model nebulae to estimate the factors by which observed ionic con
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17. Multiphoton fluorescence excitation: new spectral windows for biological nonlinear microscopy.
Intrinsic, three-dimensionally resolved, microscopic imaging of dynamical structures and biochemical processes in living preparations has been realized by nonlinear laser scanning fluorescence microscopy. The search for useful two-photon and three-photon excitation spectra, motivated by the emergence of nonlinear microscopy as a powerful biophysical instrume
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18. The [NeIV] Lines in High Excitation Gaseous Nebulae
The „forbidden” lines of three times ionized neon are among the most precious indicators of electron temperature and excitation. They are also predicted to be among the strongest lines observed in the far ultraviolet spectra of high excitation nebulae.
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19. Ultraviolet spectrum and probable chemical composition of the high-excitation planetary nebula M1-1
One of the highest excitation planetary nebulae known, M1-1, was studied with the image-tube scanner on the Shane 3-m telescope at Lick Observatory and with the International Ultraviolet Explorer. Large fractions of abundant elements such as C, N, O, S, and Ar exist in unobservable stages of ionization. Hence, it is difficult to establish the chemical compos
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20. Time-Resolved Fluorescence Spectroscopy and Imaging of DNA Labeled with DAPI and Hoechst 33342 Using Three-Photon Excitation
We examined the fluorescence spectral properties of the DNA stains DAPI (4′,6-diamidino-2-phenylindole, hydrochloride) and Hoechst 33342 (bis-benzimide, or 2,5′-bi-1H-benzimidazole2′-(4-ethoxyphenyl)-5-(4-methyl-1-piperazinyl)) with two-photon (2hν) and three-photon (3hν) excitation using femtosecond pulses from a Ti:sapphire laser from 830 to 885 nm
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21. Ultraviolet resonance Raman excitation profiles of nucleic acid bases with excitation from 200 to 300 nanometers.
Raman spectra are presented for dilute aqueous solutions of the four ribonucleotides AMP, GMP, UMP, and CMP obtained with laser excitation at 299, 266, 253, 240, 229, 218, 209, and 200 nm. Distinct evidence of strong, selective resonance enhancement is obtained. Low-resolution excitation profiles have been constructed for the strongest bands by using the pho
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22. Rapid screening of Veillonella by ultraviolet fluorescence.
Among 51 strains of anaerobic gram-negative cocci belonging to the family Veillonellaceae, all strains of Veillonella (V. parvula and V. alcalescens) displayed red fluorescence under long-wave (366 nm) ultraviolet light, whereas no Acidaminococcus or Megasphaera demonstrated fluorescence. In contrast to Bacteroides melaninogenicus, growth of Veillonella does
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23. Epidermal trans-urocanic acid and the UV-A-induced photoaging of the skin
The premature photoaging of the skin is mediated by the sensitization of reactive oxygen species after absorption of ultraviolet radiation by endogenous chromophores. Yet identification of UV-A-absorbing chromophores in the skin that quantitatively account for the action spectra of the physiological responses of photoaging has remained elusive. This paper re
The National Academy of Sciences.
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24. Properties of Squid Axon Membrane as Revealed by a Hydrophobic Probe, 2-p-Toluidinylnaphthalene-6-Sulfonate
A hydrophobic probe, 2-p-toluidinylnaphthalene-6-sulfonate (TNS), was introduced into the interior of a squid giant axon and fluorescene properties of the TNS-stained axon were examined under illumination with polarized ultraviolet light. A transient reduction in fluorescence was observed when the axon was stimulated electrically. The light waves contributin