REPOSITÓRIO INSTITUCIONAL DA UNIVERSIDADE DO VALE DO PARAÍBA

O Repositório da Produção Intelectual da Univap tem como objetivo armazenar, preservar e disseminar a memória institucional, oferecendo acesso à produção científica, como trabalhos de conclusão da graduação, dissertações, tese e artigos científicos. Os dados e plano de gestão produzidos por pesquisadores e estudantes da Univap também poderão ser disponibilizados, dependendo da política de acesso do projeto em virtude de restrições impostas pelo registro de propriedade intelectual.

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Agora exibindo 1 - 5 de 8
  • Faculdade de Ciências da Saúde
  • Faculdade Sociais Aplicadas e Comunicação
  • Faculdade de Direito
  • Faculdade de Educação e Artes
  • Faculdade de Engenharias, Arquitetura e Urbanismo

Submissões Recentes

Item
Estudo e otimização da produção de vidro bioativo (BG) por fusão
(2022) Santos, Kennedy Wallace dos; Costa, Karen Julie Santos Grancianinov; Lauda, Diogo Ponte
Item
Processo para produção de lipídeos para uso em biocombustíveis utilizando a fração orgânica de lixo urbano
(2024) Pradella, José Geraldo da Cruz; Vieira, Lúcia; Costa, Maricilia Silva; Bosso, Geisler Chbane; Jofre, Jorge Benedito Freire; Souza, Jorge Damião de; Sousa, Juçara Cristina Pereira; Sonnewend, Lais; Barboza, Maria Antonia de Mello e Albuquerque; Couto, Rafaela; Cordeiro, Thaina Barbosa de Lima
Item
Glycolaldehyde formation mediated by interstellar amorphous ice: a computational study
(Royal Astronomical Society) Paiva, Mateus Augusto Martins; Pilling, Sergio; Mendoza, Edgar; Galvão, Breno Rodrigues Lamaghere; Abreu, Heitor Avelino de
Glycolaldehyde (HOCH2CHO) is the most straightforward sugar detected in the Interstellar Medium (ISM) and participates in the formation pathways of molecules fundamental to life, red such as ribose and derivatives. Although detected in several regions of the ISM, its formation route is still debated and its abundance cannot be explained only by reactions in the gas phase. This work explores a new gas-phase formation mechanism for glycolaldehyde and compares the energy barrier reduction when the same route happens on the surface of amorphous ices. The first step of the mechanism involves the formation of a carbon–carbon bond between formaldehyde (H2CO) and the formyl radical (HCO), with an energy barrier of 27 kJ mol−1 (gas-phase). The second step consists of barrierless hydrogen addition. Density functional calculations under periodic boundary conditions were applied to study this reaction path on 10 different amorphous ice surfaces through an Eley–Rideal type mechanism. It was found that the energy barrier is reduced on average by 49 per cent, leading in some cases to a 100 per cent reduction. The calculated adsorption energy of glycolaldehyde suggests that it can be promptly desorbed to the gas phase after its formation. This work, thus contributes to explaining the detected relative abundances of glycolaldehyde and opens a new methodological framework for studying the formation routes for Complex Organic Molecules (COMs) in interstellar icy grains.
Item
Gas-phase metallicity determinations in nearby AGNs with SDSS-IV MaNGA: evidence of metal-poor accretion
(Royal Astronomical Society) Nascimento, Janaína Correa do; Dors Junior, Oli Luiz; Bergmann, Thaisa Storchi; Mallmann, Nícolas Dullius; Riffel, Rogério; Ilha, Gabriele da Silva; Riffel, Rogemar André; Rembold, Sandro Barboza; Deconto-Machado, Alice; Costa, Luiz N. da; Armah, Mark
We derive the metallicity (traced by the O/H abundance) of the narrow-line region (NLR) of 108 Seyfert galaxies as well as radial metallicity gradients along their galaxy discs and of these of a matched control sample of no active galaxies. In view of that, observational data from the SDSS-IV MaNGA survey and strong emission-line calibrations taken from the literature were considered. The metallicity obtained for the NLRs was compared to the value derived from the extrapolation of the radial oxygen abundance gradient, obtained from H II region estimates along the galaxy disc, to the central part of the host galaxies. We find that, for most of the objects (∼ 80 per cent), the NLR metallicity is lower than the extrapolated value, with the average difference (D ) between these estimates ranging from 0.16 to 0.30 dex. We suggest that D is due to the accretion of metal-poor gas to the AGN that feeds the nuclear supermassive black hole (SMBH), which is drawn from a reservoir molecular and/or neutral hydrogen around the SMBH. Additionally, we look for correlations between D and the electron density (Ne), [O III]λ5007, and H α luminosities, extinction coefficient (AV) of the NLRs, as well as the stellar mass (M∗) of the host galaxies. Evidence of an inverse correlation between the D and the parameters Ne, M∗, and Av was found.