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Materials Sciences and Applications 2011年第4期2卷 284-287页

作者： Neilo Marcos Trindade Américo Tabata rosa maria fernandes scalvi Luis Vicente de Andrade scalvi 不详

Results of photoluminescence measurements for natural and synthetic alexandrite (BeAl2O4:Cr3+) are presented, where the samples are excited by the 488 nm line of an Ar+ laser, at different temperatures. The main issue is the analysis of the Cr3+ transition in the chrysoberyl matrix (BeAl2O4), with major technological application as active media for laser action. Results indicate anomalous behavior of Cr33+ transition depending on the measurement temperature. A simple model to explain the phenomena is suggested.

关键词： Alexandrite Luminescence Cr3+ Transitions Optical Absorption

Photo-Induced Thermally Stimulated Depolarization Current (TSDC) in Natural and Synthetic Alexandrite (BeAl₂O₄:Cr³⁺)

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Materials Sciences and Applications 2016年第12期7卷 881-894页

作者： Neilo Marcos Trindade Ana Regina Blak Elisabeth Mateus Yoshimura Luis Vicente de Andrade scalvi rosa maria fernandes scalvi Sã o Paulo Federal Institute S&atilde o Paulo Brazil Institute of Physics University of S&atilde o Paulo S&atilde o Paulo Brazil Department of Physics S&atilde o Paulo State University Bauru Brazil

The investigation of electrical properties in alexandrite (BeAl2O4:Cr3+) in synthetic and natural forms is presented in this paper. Alexandrite is a rare and precious mineral that changes color according to the light incident on it. In the synthetic form, it is used technologically as an active laser medium. The electrical characterization was obtained using the Thermally Stimulated Depolarization Current (TSDC) technique, an interesting tool to study the behavior of impurities in insulators. Alexandrite presented the electric dipole relaxation phenomenon, both in natural and in synthetic samples. It was possible to observe TSDC bands for the synthetic sample at around 170 K, and at around 175 K for the natural sample. Besides, photo-induced TSDC measurements were performed through the excitement of the samples by using a continuous wave argon laser. In addition, photoluminescence measurements were performed to verify in advance whether the laser light would be absorbed by the sample, and in order to complement the photo-induced TSDC measurements analysis. The results of photo-induced TSDC experiments have contributed to the understanding of the TSDC bands behavior: the results obtained with the technique suggest that there is an effective participation of Cr3+ ions in the formation of TSDC bands because they were more intense when the sample was exposed to the argon laser beam.

关键词： Alexandrite Chrysoberyl Thermally Stimulated Depolarization Current (TSDC) Photoluminescence Photo-Induced

Bioactive extracts of red seaweeds Pterocladiella capillacea and Osmundaria obtusiloba(Floridophyceae:Rhodophyta) with antioxidant and bacterial agglutination potential

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Asian Pacific Journal of Tropical Medicine 2016年第4期9卷 363-370页

作者： Daniel Barroso de Alencar Fátima Cristiane Teles de Carvalho rosa Helena Rebouas Daniel Rodrigues dos Santos Kelma maria dos Santos Pires-Cavalcante Rebeca Larangeira de Lima Bárbara Mendes Baracho Rayssa Mendes Bezerra Francisco Arnaldo Viana Regine Helena Silva dos fernandes Vieira Alexandre Holanda Sampaio Oscarina Viana de Sousa Silvana Saker-Sampaio Laboratrio de Produtos Naturais Marinhos.Departamento de Engenharia de Pesca Universidade Federal do Ceará.Campus do Pici.Ar.Mister Hull.s/nCaixa Postal 6043 Laboratrio de Microbiologia Ambiental e do Pescado.Instituto de Ciências do Mar.Universidade Federal do Ceará.Av.da Abolicao 3207 Laboratrio de Microbiologia Ambiental e do Pescado.Instituto de Ciências do Mar.Universidade Federal do Ceará Laboratrio de Produtos Naturais Marinhos.Departamento de Engenharia de Pesca Universidade Federal do Ceará Laboratrio de Cromatografia Departamento de QuimicaUniversidade do Estado do Rio Grande do NorteCampus Universitário Central

Objective:To evaluate the antioxidant,antibacterial and bacterial cell agglutination activities of the hexane(Hex) and 70%ethanol(70%EtOH) extracts of two species of red seaweeds Pterocladiella capillacea(***) and Osmundaria ***:In vitro antioxidant activity was determined by DPPH radical scavenging assay,ferric-reducing antioxidant power assay,ferrous ion chelating assay,β-carotene bleaching assay and total phenolic content *** activity was tested using the method of disc diffusion on Mueller-Hinton *** ability of algal extracts to agglutinate bacterial cells was also ***:The 70%EtOH extract of the two algae showed the highest values of total phenolic content compared to the Hex *** results of DPPH for both extracts(Hex,70%EtOH) of Osmundaria obtusiloba(43.46%and 99.47%) were higher than those of ***(33.04%and 40.81%) at a concentration of 1 000 μg/*** for the ferrous ion chelating,there was an opposite behavior,extracts of *** had a higher *** extracts showed a low ferric-reducing antioxidant power,with optical density ranging from0.054 to *** activities of all extracts evaluated for β-carotene bleaching were above 40%.There was no antibacterial activity against bacterial strains ***,the extracts of both species were able to agglutinate bacterial Gram positive cells of Staphylococcus aureus and Gram negative cells of Escherichia coli,multidrug-resistant Salmonella and Vibrio *** This is the first report of the interaction between these algal extracts,rich in natural compounds with antioxidant potential,and Gram positive and Gram negative bacterial cells.

关键词： Bioactive compounds Antioxidant Bacterial agglutination Rhodophyta

Factors Associated with the Infection by Plasmodium vivaxin Children and Adolescents from the Brazilian Amazon Basin

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Advances in Infectious Diseases 2020年第2期10卷 140-147页

作者： rosa maria Dias Larissa Rodrigues da Costa Agostilina Renata dos Santos da Cruz Ramos Andrea Graças Ferreira Frazã o Clá udia Daniele Tavares Dutra Fernanda maria Lima Moura Isameriliam rosaulem Pereira da Silva José Luiz fernandes Vieira Faculty of Nutrition Institute of Health Sciences Para Federal University Belem Brazil Pharmacy Faculty Campus Universitario do Guama Para Federal University Belem Brazil

Objective: To investigate the factors associated with malaria vivax infection in children and adolescents from an endemic area in the Eastern portion of the Brazilian Amazon basin. Methods: A case-control study was carried out in the municipality of Anajas, Brazil, from January 2016 to September 2017. Questionnaires were applied to the relative or the legal tutors of children and adolescents with questions regarding social and economic status, educational degree, knowledge about malaria, and the use of protective measures against mosquito bites. Anthropometric measures were performed in children and adolescents. Results: A total of 58 cases and 61 controls were included in the study. Most of the participants were male, eutrophics, and their relatives presented low educational degrees as well as low social and economic status. The knowledge of malaria was limited, but the percentage of individuals using long-lasting insecticidal nets was high. The presence of peri-domiciliary breeding sites for Anopheles vector was the most critical factor for malaria. Conclusion: The occurrence of malaria was associated with low social and economic status, a low educational degree, the unfamiliarity with malaria and the presence of breeding sites for Anopheles mosquito surrounding individual domiciles.

关键词： Infectious Diseases Malaria Epidemiology Risk Factor