2 research outputs found
Thermodynamics and kinetics of the nickel(II)-salicylhydroxamic acid system. Phenol rotation induced by metal ion binding
No full textThe kinetics and the equilibria of Ni(II) binding to p-hydroxybenzohydroxamic acid (PHBHA) and salicylhydroxamic acid (SHA) have been investigated in an aqueous solution at 25 degrees C and I = 0.2 M by the stopped-flow method. Two reaction paths involving metal binding to the neutral acid and to its anion have been observed. Concerning PHBHA, the rate constants of the forward and reverse steps are k(1) = (1.9 +/- 0.1) x 10(3) M-1 s(-1) and k(-1) = (1.1 +/- 0.1) x 10(2) s(-1) for the step involving the undissociated PHBHA and k(2) = (3.2 +/- 0.2) x 10(4) M-1 s(-1) and k(-2) = 1.2 +/- 0.2 s(-1) for the step involving the anion. Concerning SHA, the analogous rate constants are k(1) = (2.6 +/- 0.1) x 10(3) M-1 s(-1), k(-1) = (1.3 +/- 0.1) x 10(3) s(-1), k(2) = (5.4 +/- 0.2) x 10(3) M-1 s(-1), and k(-2) = 6.3 +/- 0.5 s(-1). These values indicate that metal binding to the anions of the two acids concurs with the Eigen-Wilkins mechanism and that the phenol oxygen is not involved in the chelation. Moreover, a slow effect was observed in the SHA-Ni(II) system, which has been put down to rotation of the benzene ring around the C-C bond. Quantum mechanical calculations at the B3LYP/lanL2DZ level reveal that the phenol group in the most stable form of the Ni(II) chelate is in trans position relative to the carbonyl oxygen, contrary to the free SHA structure, where the phenol and carbonyl oxygen atoms both have cis configuration. These results bear out the idea that the complex formation is coupled with phenol rotation around the C-C bond
Propostas didáticas desenvolvidas no contexto de um curso remoto de Educação Ambiental em tempos de covid-19
No full textThis article corresponds to a master\u27s research, defended by the first author in 2022 and it aims to study 22 didactic proposals of Environmental Education for teachers who work in the 4th and 5th year of basic education. The research is qualitative, having as research corpus the researcher\u27s diary and the didactic proposals developed in a collaborative way by teachers during a remote course of Environmental Education The elaborated proposals showed themselves one of the possible paths for the teachers develop a collective work. This can broaden their and the community\u27s perception of socio-environmental issues.Este artículo corresponde a una investigación de maestría, del primer autor, defendida en 2022 y tiene como objetivo estudiar 22 propuestas didácticas de Educación Ambiental para docentes que actúan en el 4° y 5° año de educación básica. La investigación es de carácter cualitativo, teniendo como corpus de investigación el diario del investigador y las propuestas didácticas desarrolladas de manera colaborativa por los docentes durante la realización de un curso a distancia de Educación. Ambiental. Las propuestas elaboradas demostraron ser una de las vías posibles para que los docentes desarrollen un trabajo colectivo que pueda ampliar sus perspectivas y las de la comunidad escolar para las cuestiones socioambientales.Este artigo corresponde a um recorte de pesquisa de mestrado, da primeira autora, defendida no ano de 2022 e tem como objetivo analisar Propostas Didáticas (PD) de Educação Ambiental desenvolvidas por professores que atuam na educação básica. A pesquisa é de natureza qualitativa sendo o corpus de pesquisa constituído por diário da pesquisadora e por 18 (dezoito) PD elaboradas de forma colaborativa pelos participantes do curso de Educação Ambiental remoto. Da análise dos dados emergiram duas categorias: 1) Reconhecimento do Contexto Escolar; 2) Articulação entre Tema, Contexto Escolar e Justificativa da PD; que articuladas entre si se mostraram caminhos para que os professores desenvolvam um trabalho coletivo que possa ampliar seus olhares e os da comunidade escolar para questões socioambientais
