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Nuclear Activity in Circumnuclear Ring Galaxies

International Journal of Astronomy and Astrophysics 2016年第3期6卷 219-235页

作者： María P. Agüero Rubén J. díaz horacio dottori Observatorio Astronómico de Córdoba UNCand CONICET Córdoba Argentina ICATE CONICET San Juan Argentina Gemini Observatory La Serena Chile Instituto de Física UFRGS Porto Alegre Brazil

We have analyzed the frequency and properties of the nuclear activity in a sample of galaxies with circumnuclear rings and spirals (CNRs), compiled from published data. From the properties of this sample a typical circumnuclear ring can be characterized as having a median radius of 0.7 kpc (mean 0.8 kpc, rms 0.4 kpc), located at a spiral sa/Sb galaxy (75% of the hosts), with a bar (44% weak, 37% strong bars). The sample includes 73 emission line rings, 12 dust rings and 9 stellar rings. The sample was compared with a carefully matched control sample of galaxies with very similar global properties but without detected circumnuclear rings. We discuss the relevance of the results in regard to the AGN feeding processes and present the following results: 1) bright companion galaxies seem not to be important for the appearance of CNRs, which appear to be more related to intrinsic properties of the host galaxies or to minor merger processes;2) the proportion of weak bars in galaxies with a CNR is higher than expected;3) the incidence of Seyfert (Sy) activity coeval with CNRs is significantly larger than the rate expected from the morphological distribution of the host galaxies;4) the rate of Sy 2 to Sy 1 type galaxies with CNRs is about three times larger than the expected ratio for galaxies without CNRs and is opposite to that predicted by the geometric paradigm of the classical unified model for AGNs, although it does support the hypothesis that Sy 2 activity is linked to circumnuclear star formation. The possible selection effects of the sample are discussed, and we conclude that the detected trends are strong enough to justify high quality observations of as large as possible set of galaxies with circumnuclear rings and their matched control samples.

关键词： Galaxies Spiral Nuclei Structure dynamics Active

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A new method for quantification of total polyphenol content in medicinal plants based on the reduction of Fe(III)/1,10-phenanthroline complexes

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Advances in Biological Chemistry 2013年第6期3卷 525-535页

作者： Monica Gabriela do santo Cecilia Veronica Nunez horacio dorigan Moya Faculdade de Medicina da Fundacao do ABC CEPES(Centro de EstudosPesquisaPrevencao e Tratamento em Saúde)Santo AndréBrazil Laboratório de Bioprospeccao e Biotecnologia COTI(Coordenacao de Tecnologia e Inovacao)INPA(Instituto Nacional de Pesquisas da Amazonia)ManausBrazil

This paper proposes an alternative analytical spectrophotometric method for the total polyphenol quantification in the aqueous extract of plants. When these extracts are added to solutions of Fe(III), in presence of 1,10-phenanthroline, the absorbance values at 551 nm (A511nm) due to the complexes formed are proportional to the total polyphenol concentration expressed as pyrogallic acid (PA). A typical calibration graph of A511nm values vs. PA is linear from 0.16 to 0.64 mg L-1 (r = 0.994, n = 6) with a limit of detection 0.041 mg L-1. The results of the polyphenol content of the aqueous extracts of twenty medicinal Brazilian plants obtained with the proposed method were compared with values using the Folin-Ciocalteu reagent. A paired t-test revealed no statistically significant difference for the species analyzed. The total antioxidant capacity of the same twenty extracts was determined based on the scavenging of stable radical dPPH.

关键词： Polyphenols Medicinal Brazilian Plants 1,10-Phenanthroline Iron(III) Antioxidant Activity

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