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Unequivocal structural assignments of three cardanol derivatives: an experimental and theoretical approach
(2019) Barbosa, Layla Rosario; Souza, Daiane Santana; Queiroz Júnior, Luiz Henrique Keng; Cunha Neto, Alvaro; Lima, Dênis Pires de; Beatriz, Adilson; Romão, Wanderson; Castro, Eustaquio Vinicius Ribeiro de; Lacerda Júnior, Valdemar
Cardanol was obtained by vacuum distillation of ‘‘cashew nut shell liquid’’ (CNSL). Cardanol is a by-product of cashew production and a building block for chemical synthesis; cardanol and its derivatives can be used for different types of applications. Three of these compounds are the subject of the present NMR study and theoretical comparison. 1H and 13C NMR signals were assigned using 1D and 2D NMR experiments. The DFT/B3LYP method using the cc-pVTZ basis set was employed for the calculations of the 1H and 13C NMR chemical shifts (δ). The obtained data were used as an auxiliary tool for unequivocal assignment of all 1H and 1³C NMR signals. For these compounds, the adopted theoretical model was sufficient to obtain a good description of the chemical shifts.
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Colaboração educativa: uma proposta metodológica para ensino e pesquisa baseados na robótica pedagógica, epistemologia genética e educação libertadora
(2022) Pinheiro, Ricardo Silverio Gomes; Soares, Márlon Herbert Flora Barbosa
This paper discusses different meanings of collaboration and cooperation based on Piagetian and Freirean concepts among others. We also present a proposal for resignification of these terms in education, which resulted in two processes: educational collaboration and educational cooperation. By combining educational collaboration with pedagogical robotics, university students and a professor started with the context of civil construction to design a robot that was able to identify electrochemical corrosion in concrete structures. Two categories emerged from this process (questions and suggestions) and were analyzed in their form and content through a scientific research method proposed in three stages, based on educational collaboration: hierarchical ratio, categorical ratio and subcategorical qualitative analysis. The educational collaboration culminated in collaborative learning and proved to be a contextualized teaching method in which there is active student participation. Collaborative learning was evidenced by joint construction of knowledge to construct the robot, a result of the rebalance between individual and social factors.
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Construindo conhecimento sobre a biologia evolutiva no ensino médio: a operação, a assimilação e a interação lúdica em um jogo pedagógico
(2022-04) Moraes, Fernando Aparecido de; Soares, Márlon Herbert Flora Barbosa
This article presents someresults of a doctoral thesis on the relationship between the experiences of the researcher, as a teacher, with what the specific literature in the area of Biology Teaching points out about the needs of teaching Biological Evolution in Basic Education. Thepurpose of this study was to provide theoretical support for thinking about possibilities for building knowledge of concepts related to Biological Evolution in the classroom based on the use of a playful pedagogical strategy, a pedagogical game. Initially, the study presented a theoretical discussion on aspects of teaching Biological Evolution in Basic Education, relating this teaching to the need for innovation in terms of strategies. Then, the theoretical discussion characterized the pedagogical game relating it to Piaget's Genetic Epistemology. After a brief theoretical discussion, we presented the methodological procedures of the qualitative research carried out with 21 volunteer students, from two classes of the 3rd grade of High School of a Full Time Education Center, located in the municipality of Jataí, state of Goiás. The analysis took place from the content constructed during the application of the game to students, recorded through audio-visual recording and later transcribed. In order to evaluatethe game, seeking to verify possibilities of allowing the construction of knowledge of evolutionary concepts, three categories that emerged in the pre-content analysis were brought to discussion: operation, assimilation and playful interaction. Throughoutthe analysis, at various moments in the application of the game, situations of operation, assimilation and playful interaction were observed. In these moments, it was also evident that abstract evolutionary concepts selected for the game, such as common ancestor and speciation, were collectively operated and assimilated by the students.At the end, based on the results achieved, the authors reflect on the importance of the pedagogical game, above all, in the teaching and learning process of Biological Evolution in Basic Education.
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Improving quantitative 13C NMR performance by an adiabatic scheme
(2018) Wollinger, Wagner; Fernandes, Jane Luíza Nogueira; Queiroz Júnior, Luiz Henrique Keng; Garrido, Bruno Carius; Aquino Neto, Francisco Radler de
NMR is a primary method of measurement that provides quantitative traceable results without the need for a standard of the same measurand. Despite the advantages of the 1H nucleus, such as high sensitivity, short relaxation times and widespread distribution in organic compounds, some molecules present only labile H atoms, or the 1H peaks of a sample may overlap with impurities. With the CHORAD scheme – a combination of the pulse sequence CHORUS and adiabatic modulation for 1H decoupling – this study has shown that 13C NMR can be used for quantitative analyses with a bias smaller than 2% and expanded uncertainty of 0.7% (for a confidence level of 95%). Since 13C is found with significant non-statistic isotope fractionation, all the peaks of the sample and internal standard should be integrated and their bulk 13C abundances obtained by isotope ratio mass spectrometry (IRMS) must be considered to meet quantitative requirements. Future experimental work may be performed to test this procedure for complex matrix samples. This approach also proved to be suitable for studies of site-specific 13C distribution and led to better heteronuclear decoupling when compared with the use of adiabatic decoupling with ordinary hard 90° pulses, a combination extensively reported in the literature over the last decade. An examination of the molecules studied in this work and others from the literature revealed an overall trend in the 13C intramolecular profile – hydrogen-containing positions are often 13C-depleted. A potential contribution of 1JCH coupling to these results is discussed.
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Chemical investigation and anatomical aspects of wood residues from Hymenaea courbaril L, Platymiscium ulei Harms, Hymenolobium petraeum Ducke
(2022) Lima, Jennifer Araújo de Oliveira; Hayasida, Willian; Garcia, Mauro Galucio; Freitas, Jorge Alves de; Nascimento, Claudete Catanhede do; Queiroz Júnior, Luiz Henrique Keng; Lima, Maria da Paz
In recent years, the interest in the propagation of native forest species has intensified with the aim of recovering degraded areas and the restoration of the landscape. As such, some species of Fabaceaeare considered promising woody species for planting in reforestation programs and agroforestry systems. In the present paper, the authors complement the need for studies related to secondary metabolites of the woody speciesHymenaea courbaril L. Platymiscium ulei Harms and Hymenolobium petraeum Ducke. Thus, the phytochemical study of H. courbaril led to the isolation and identification of diterpenes eperuic acid (1) and methyl eperuate (2); triterpenes oleanolic acid (3) andhederagenin(8); flavonoides quercetin (4), fisetinediol (5), liquiritigenin (6) and 3-methoxy-5,7,3',5'-tetrahydroxyflavanonol (7).P. ulei gave pterocarpane homopterocarpin (9) and coumarin scoparone(10); H. petraeum gave isoflavan sativan (11), in addition to the amino acidtyrosine(12). Flavonoids were the predominant constituents in the three species of Fabaceae; however, the presence of isoflavonoids in Platymiscium ulei and Hymenolobium petraeum is probably associated with the resistance of this high density wood to pathogenic fungi.