Argumentação: uma proposta didática para compreensão de modelagem

A atividade desenvolvida foi realizada com alunos do primeiro ano do Ensino Médio na cidade de São Caetano, Pernambuco-Brasil. E consistiu em uma intervenção realizada por Graduandos e Mestrandos da área de Química, que objetivou a construção de uma atividade que envolvesse a argumentação, a fim de que os alunos pudessem compreender os conceitos de modelagem a partir da discussão. Os estudantes foram instigados a elaborarem desenhos da evolução de um bolo com intuito de realizarem a construção de modelos mentais, que aconteciam por meio de direcionamentos e questionamentos por parte dos investigadores. Os resultados dessa pesquisa foram satisfatórios e relevantes para o meio acadêmico podendo ser utilizados para pesquisas vindouras. Identificou-se que a argumentação emergia nas falas dos estudantes e que esta viabilizou e norteou as discussões do debate permitindo a elaboração e o desenvolvimento de argumentos a partir de outras concepções de modelos e representações, bem como a compreensão no campo empírico e real, potencializando e desenvolvendo assim o conhecimento cognitivo e metacognitivo dos mesmos, na construção do entendimento de modelagem.Facultad de Humanidades y Ciencias de la Educació

Argumentação: uma proposta didática para compreensão de modelagem

A atividade desenvolvida foi realizada com alunos do primeiro ano do Ensino Médio na cidade de São Caetano, Pernambuco-Brasil. E consistiu em uma intervenção realizada por Graduandos e Mestrandos da área de Química, que objetivou a construção de uma atividade que envolvesse a argumentação, a fim de que os alunos pudessem compreender os conceitos de modelagem a partir da discussão. Os estudantes foram instigados a elaborarem desenhos da evolução de um bolo com intuito de realizarem a construção de modelos mentais, que aconteciam por meio de direcionamentos e questionamentos por parte dos investigadores. Os resultados dessa pesquisa foram satisfatórios e relevantes para o meio acadêmico podendo ser utilizados para pesquisas vindouras. Identificou-se que a argumentação emergia nas falas dos estudantes e que esta viabilizou e norteou as discussões do debate permitindo a elaboração e o desenvolvimento de argumentos a partir de outras concepções de modelos e representações, bem como a compreensão no campo empírico e real, potencializando e desenvolvendo assim o conhecimento cognitivo e metacognitivo dos mesmos, na construção do entendimento de modelagem.Facultad de Humanidades y Ciencias de la Educació

Argumentação: uma proposta didática para compreensão de modelagem

A atividade desenvolvida foi realizada com alunos do primeiro ano do Ensino Médio na cidade de São Caetano, Pernambuco-Brasil. E consistiu em uma intervenção realizada por Graduandos e Mestrandos da área de Química, que objetivou a construção de uma atividade que envolvesse a argumentação, a fim de que os alunos pudessem compreender os conceitos de modelagem a partir da discussão. Os estudantes foram instigados a elaborarem desenhos da evolução de um bolo com intuito de realizarem a construção de modelos mentais, que aconteciam por meio de direcionamentos e questionamentos por parte dos investigadores. Os resultados dessa pesquisa foram satisfatórios e relevantes para o meio acadêmico podendo ser utilizados para pesquisas vindouras. Identificou-se que a argumentação emergia nas falas dos estudantes e que esta viabilizou e norteou as discussões do debate permitindo a elaboração e o desenvolvimento de argumentos a partir de outras concepções de modelos e representações, bem como a compreensão no campo empírico e real, potencializando e desenvolvendo assim o conhecimento cognitivo e metacognitivo dos mesmos, na construção do entendimento de modelagem.Facultad de Humanidades y Ciencias de la Educació

Influence of additives in the transesterification of crude coconut oil catalyzed by Burkholderia cepacia lipase immobilized onto agro-industrial waste fibers / Influência de aditivos na transesterificação de óleo de coco bruto catalisado por lipase de Burkholderia cepacia imobilizada em fibras de resíduo agroindustrial

In this study was verified the influence of different additives in the transesterification reaction of the crude coconut oil catalyzed with lipase from Burkholderia cepacia  immobilized by physical adsorption onto palm fiber originated from agroindustrial wastes. Reactions was performed under the conditions: molar ratio 1:7 (oil:alcohol), 10 % biocatalyst immobilized for 96 h at 40 °C in the presence in different concentrations of additives (water, tert-butanol, molecular sieve and protic ionic liquids). The results showed that the use of all the additives in this study did not increase conversion to ethyl esters. The maximum conversion in the absence of the additives was 72 %, in the presence of water 45 ± 2 %, molecular sieve 53 ± 2 % and tert -butanol 59 ± 2 %, respectively, all in the lowest concentrations. For ionic liquids, those with higher alkyl chains had the highest conversions, but lower than in their absence

Azadirachta indica A. Juss (neem) phenolic extract inhibits human B-lymphoblastoid cells growth via cell cycle arrest, apoptosis induction, and DNA damage

Aim: As far as is known, the pharmaceutical effects of neem on human B-lymphoblastoid (TK6) cells have not been studied until now. Hence, the present study aimed to obtain neem phenolic extracts for inhibits the proliferation of TK6 cells and explore some possible underlying mechanisms involved in these effects. Methods: Hexane extract (HE) was obtained in the first step. After that, the residual hexane was removed from the neem. The dried neem sample was used in a new extraction for obtaining the ethyl acetate extract (EAE). Total phenolic compounds (TPC) and total flavonoid contents (TFC) were determined by spectrophotometric methods. Lactate dehydrogenase (LDH) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) tests were used to evaluate the cytotoxicity in TK6 cells. The stop at G0/G1 cell cycle and inducing apoptosis in the TK6 cells were analyzed by flow cytometry. For deoxyribonucleic acid (DNA) damage evaluation, the alkaline comet test was used. Results: The higher TFC (65.50 mg/g of extract ± 1.17 mg/g of extract) and TPC (52.08 mg of extract ± 0.88 mg of extract) were obtained in EAE compared to HE that was obtained TFC of 14.61 mg/g of extract ± 0.60 mg/g of extract and TPC of 3.20 mg/g of extract ± 1.20 mg/g of extract. EAE was more significantly cytotoxic to TK6 cells than HE. The apoptosis induction was higher after exposure to 15.0 µg/mL of EAE (11.29%) in comparison to 15.0 µg/mL of HE (2.52%). The G0/G1 phase increased from 72% negative control (NC) to 83% after treatment with neem extracts (15 µg/mL). Neem extracts were also able to cause DNA strand breaks in TK6 cells. Conclusions: The extraction residue from neem leaf after hexane extraction is a source important of cytotoxic and genotoxic molecules against TK6 cells, the results also can suggest that the toxic effects in TK6 cells can be provided most likely due to the presence of high content of TPC from neem extracts.The CAPES (Coordination for the Improvement of Higher Education Personnel), Program Sandwich Abroad (Process: PDSE 99999.003409/15-5) provided funding for Klebson Silva Santos’ financial support and scholarship in Portugal. This study also was funded by CNPq (National Council for Scientific and Technological Development), and FAPITEC/SE (Fundação de Apoio à Pesquisa e à Inovação Tecnológica do Estado de Sergipe). The study also was carried out with financial support from FCT/MEC through national funds and co-financed by FEDER, under the Partnership Agreement PT2020 and the project UID/QUI/50006/2013-POCI/01/0145/FEDER/007265. This work was also supported by the UIDB/50006/2020 project, funded by FCT/MCTES (Portugal, through national funds); SYSTEMIC “an integrated approach to the challenge of sustainable food systems: adaptive and mitigatory strategies to address climate change and malnutrition”, a Knowledge hub on Nutrition and Food Security, funded by FWO, INRA, BLE, MIPAAF, IZM, RCN, FCT and AEI in a joint action of JPI HDHL, JPI-OCEANS, and FACCE-JPI launched in 2019 under the ERA-NET ERA-HDHL [696295].info:eu-repo/semantics/publishedVersio

Cambuí (Myrciaria floribunda (West ex Willd.) O. Berg): A potential nutritional supplement for inhibition of COVID-19 infections / Cambuí (Myrciaria floribunda (West ex Willd.) O. Berg): Um potencial suplemento nutricional para a inibição de infecções por COVID-19

In the present study, we suggest that the Myrciaria floribunda (West ex Willd.) O. Berg fruit (cambuí) is a natural source of potential molecules against COVID-19. Extracts from orange and purple cambuí were obtained by using pressurized hot water extraction (PHWE). Extraction overall yield was 39.66 ± 1.62% and 33.00 ± 8.44% for the extracts of purple and orange cambuí, respectively. All analyzed extracts showed high total phenolic contents, especially those of purple fruits (3870.37 ± 353.09 mg GAE/100g). The total flavonoid content was 693.16 ± 180.09 and 770.08 ± 103.62 mg RE/100g for purple and orange fruit extracts, respectively. The secondary metabolite profile exhibited ellagic acid, ellagitannins, and derivatives of caffeic acid and ellagic acid. PHWE showed a good alternative for molecules separation from cambuí with promising potential for further in vitro and in vivo evaluation against Covid-19 infections

Optimization of xanthan gum production by demerara sugar using response surface methodology

Xanthan gum (XG) production using three Xanthomonas sp. strains (290, 472, and S6) was evaluated by applying a 23 full factorial central composite design response to study the interactive effects of the fermentation medium component concentrations as parameters to determine the efficiency of the gum production in batch experiments. The experimental variables were the carbon source (demerara sugar or sucrose), potassium phosphate dibasic, and magnesium sulfate. Experimental results showed the K2HPO4 concentration as the important parameter for XG production by using Xanthomonas axonopodis pv. manihotis IBSBF 290 and X. campestris pv. campestris IBSBF 472, while for the Xanthomonas sp. S6 strain, the MgSO4∙7H2O concentration was the determining factor in XG production using demerara sugar or sucrose as a carbon source. The strains of Xanthomonas 472 and S6, using demerara sugar and higher concentrations of salts, exhibited a higher yield of XG (36 and 32%) than when using sucrose and the same concentration of salts. The experimental outcomes highlighted demerara sugar as a suitable and efficient alternative carbon and micronutrient source for XG production. Despite the bacterial strain influence, the medium composition is crucial for this fermentation process. Therefore, the evaluated salts are important factors for XG production, and the demerara sugar can partially replace this mineral salt requirement as indicated by the face-centered composite experimental design due to its chemical composition. Overall, demerara sugar provides promising properties for XG production.The authors acknowledge the financial assistance from the Brazilian research funding agencies including the Co-ordination for the Improvement of Higher Education Personnel (CAPES) under Finance Code 001, a Brazilian foundation within the Ministry of Education (MEC); the National Council for Scientific and Technological Development (CNPq), a Brazilian foundation associated to the Ministry of Science, Technology, and Innovations (MCTI); the Foundation of Support to Research and Technological Innovation of the State of Sergipe (FAPITEC/SE); and the Regional Co-operative of Agrarian Reform Settlers of Sergipe’s Semi-Arid. The authors acknowledge the Foundation for Science and Technology (FCT, Portugal) for the financial support to the CISAS UIDB/05937/2020 and UIDP/05937/2020, including the postdoc grant and the contract of the two authors.info:eu-repo/semantics/publishedVersio

Effect of thermal parameters and pH on obtaining copper ferrite via EDTA-Citrate complexation method

The synthesis of ceramic materials such as ferrite has been widely studied in recent years, due to their properties that make these materials have excellent applications in technology, as well as in photocatalytic processes and as catalysts. To obtain the copper ferrite phase the EDTA-Citrate complexation method was used, varying pH (5, 7 and 9), temperature (600, 800 and 1000 °C) and calcination time (2, 7 and 12 h). Composition, morphology and structural analyzes were performed by X-ray fluorescence spectroscopy, X-ray dispersive energy, scanning electron microscopy and X-ray diffraction, respectively. Crystalline phase of copper ferrite (CuFe2O4) with tetragonal structure and secondary phase of Fe2O3 and CuO was verified by XRD analysis. Regarding the chemical composition analyzes, percentage deviations of the samples and the theoretical value for copper and iron were calculated. It was obtained minimum values of 0.16 - 0.08% (atomic%, EDS) and 16 - 8% (atomic%, XRF) in relation to copper and iron, respectively, for the sample obtained under pH 9, calcined at 600 °C for 12 h. The variation of the synthesis condition via EDTA-Citrate directly influenced the morphology of copper ferrite, presenting agglomerated particles, pore formation, irregular spheres, and even powder sintering.keywords: thermal parameters, pH, copper ferrite, EDTA-Citrate, crystallinity and morphology.

Remoção de nitrato da água utilizando bagaço de caju quimicamente modificado

O ânion nitrato (NO-3), devido sua alta solubilidade em água, é um contaminante de difícil remoção. Os métodos atualmente empregados para tratamento de água contaminada por nitrato possuem um elevado custo e não são muito eficientes, já que em alguns casos são gerados resíduos mais tóxicos que o próprio nitrato. Tecnologias contemporâneas empregadas para tratamento de efluentes aquosos têm seus mecanismos baseados no fenômeno de adsorção, em que um sólido poroso é capaz de adsorver determinadas substâncias, quando estas estão em contato. Estas tecnologias são economicamente rentáveis quando são empregados rejeitos agrícolas como adsorventes. Baseado no exposto este trabalho tem como objetivo avaliar a eficiência de remoção de nitrato de água, utilizando bagaço de caju quimicamente modificado. Os estudos foram realizados em batelada. Os ensaios de adsorção evidenciaram que o tratamento do bagaço de caju com NaOH 0,1 mol.L-1  alcançou uma eficiência de remoção de 96%, enquanto que o bagaço sem tratamento obteve remoção de 22%. O mecanismo de adsorção modelou-se a uma cinética de pseudo-segunda ordem e foi mais bem correlacionado com a isoterma de Freundlich.