01.1 - Graduação (Sede)
URI permanente desta comunidadehttps://arandu.ufrpe.br/handle/123456789/2
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Resultados da Pesquisa
Item Micofumigação contra fungos associados à doenças pós-colheita no morango(2021) Cunha, Wallingson Moura da; Gomes, André Angelo Medeiros; http://lattes.cnpq.br/2862163921055255; http://lattes.cnpq.br/9709360130790415Item Análise das compreensões de alunos após o desenvolvimento de uma intervenção didática com a temática biogás no ensino de compostos orgânicos(2019-12-18) Santos, Daysnan Nicolly Arcanjo dos; Firme, Ruth do Nascimento; http://lattes.cnpq.br/7234636790850019; http://lattes.cnpq.br/8660965015640257Contextualization in science education, and more specifically in chemistry education, has been considered as a way to enable students to find meanings for the content addressed in the classroom. In this perspective, one of the possibilities of contextualization is based on the Freirean Thematic Approach (ATF). Given several possible themes for teaching chemistry from the ATF, we highlight the theme of Biofuels, more specifically Biogas, due to its numerous environmental and economic benefits. Therefore, in this research we aimed to analyze students' understandings after the development of a didactic intervention with the theme Biogas in the teaching of organic compounds. The qualitative research was carried out in a reference school in the high school of the public school system in the north of Recife. Twenty-eight students from the third grade of high school participated, but only thirteen students participated in the study data collection, and was conducted from the following steps: 1) elaboration of the didactic intervention; 2) application of the didactic intervention; and 3) data analysis. Based on the analyzes performed, we can say that the students' understanding: 1) were positive regarding the experimental activity Biogas Production and pointed out relevant aspects that constitute the process of a biodigester, such as the use of organic matter for biogas production. ; 2) related to organic compounds involved in biogas production, such as methane production and combustion with carbon dioxide production; 3) involved relationships between biogas and socioeconomic aspects, such as the cost-benefit of biogas production for sustainability and economic issues, especially for rural areas. However, from the understanding of the identified students, it can be said that the didactic intervention does not seem to have guaranteed students' understanding of other aspects related to organic compounds, such as nomenclature of organic compounds involved in the functioning of the biodigester for biogas. In this direction, aiming at a new research agenda, we propose that the didactic intervention elaborated, developed and analyzed in this research be rethought in order to subsidize the students in the understanding of other chemical contents related to the organic compounds involved in the biogas theme.Item Estudo teórico do equilíbrio tautomérico e conformacional de B-dicetonas(2021-07-21) Silva Filho, Alex Sandro Nascimento da; Batista, Hélcio José; http://lattes.cnpq.br/1234630357325796; http://lattes.cnpq.br/5012359684272037Beta-diketones are a class of organic compounds characterized through the presence of two carbonyls separated by a carbon unit. Historically, the study of their structures provided the first experimental data on the phenomenon called keto-enol tautomerism, in addition to the particular equilibrium between different enol forms being a source of data for the study of low-energy barrier proton transfer processes. In these works, in general, thermodynamic analyzes are based on nuclear magnetic resonance (NMR) spectroscopy and the evaluation of the constants of keto-enol and enol-enol equilibria are performed from theoretical studies using computational chemistry tools, analyzing minimum structures of each equilibrium. Few theoretical works on beta-diketone systems estimate the energy barriers of tautomerism and its relationship with the substituent and the polarity of the medium, and these few do so using methods of high computational cost with large basis sets, and very often without a study of vibrational and electronic absorption spectroscopies. With the motivation to contribute in this research area, a theoretical study of the conformational, keto-enol and enol-enol equilibria for the following series of B-diketones was carried out in this work: acetylacetone (Acac), benzoylacetone (Bzac), dibenzoylacetone (Dbm), trifluordibenzoylacetone (Btfa), trifluoroacetylacetone (Tfac) and Haxafluoroacetylacetate (Hfac), where low cost computational methods were employed, namely the semi-empirical AM1 method, the density functional theory method with the B3lyp functional and the ab initio Hartree-Fock (HF) method, the last two using the 6-31G basis. The results according to the used methods showed agreement with experimental data from the literature in respect to the ketone tautomers having greater conformational rotational freedom on the ketone ring against to the enolic tautomers. In respect to the keto-enol equilibrium, the influence of the substituent groups on energy barriers is observed, in the case of the studied compounds, the phenyl group (Ph) reducing the barrier height, and the trifluoromethyl group (CF3) increasing it. It is also noted that the transition states (TS) of the keto-enol equilibrium behave according to Hammond's postulate, having their energy destabilized when it has a structure similar to the keto form, which has greater energy than the enol, and stabilized energy, when it resembles the enol tautomer, in general more stable. In the enol-enol equilibrium, the barrier has the same behavior as in the keto-enol case, being influenced by the substituents. Using theoretical vibrational analysis, Gibbs barrier estimation, structural prediction, population analysis of molecular orbitals and prediction of ultraviolet absorption spectra, it was verified that the transition state presents a structure stable enough to provide the establishment of an ultrafast equilibrium between the reagent and product minima. The beta-diketones that have phenyl groups allow to characterize this equilibrium more consistently. To the hydrogen centralization is ascribed a larger ionic or covalent character, a greater TS barrier being found when covalent and smaller when ionic. The Ph substituting group reinforces the ionic character, while the CH3 and CF3 groups the covalent character.Item Avaliação in vitro de derivados 1,2-alcanodiamina frente ao Mycobacterium tuberculosis sensível e multidroga resistente(2019-07-09) Laet, João Paulo de Lucena; Pimentel, Lílian Maria Lapa Montenegro; Burgos, Fábia Regina Nascimento Fernando; http://lattes.cnpq.br/3776642205741967; http://lattes.cnpq.br/6066865382706623; http://lattes.cnpq.br/3972432719752724Mycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis (TB), an infectious-contagious disease, considered one of the deadliest in the world. TB remains a major global public health problem and so far, there has been no effective way to eradicate it. A major change in TB trajectory occurred with the introduction of the first anti-TB drugs and consequently the emergence of resistance forms to antimycobacteria, resistant multidrug tuberculosis (MDR-TB) and extensively resistant tuberculosis (XDR-TB). From this, the need arises for new drugs to be proposed in the treatment of this disease. The present study aims to evaluate diamine derivatives, related to ethambutol, against sensitive Mtb and MDR. Ten compounds derived from the class 1,2-alkanediamine were synthesized and characterized structurally by the pharmaceutical chemistry laboratories of the University of Salamanca and provided through international cooperation. For the biological tests, the standard reference strain H37Rv (ATCC 27294) was classified as a strain sensitive to all drugs used to treat TB and a clinical isolate of a patient affected by pulmonary tuberculosis with a MDR profile, provided by the Health Laboratory Public of Pernambuco. Minimum Inhibitory Concentration (MIC) determined the evaluation of compound activity in 96-well plates by the colorimetric microdilution method. For cytotoxicity (CC50) the MTT test (3- (4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium bromide) was used with the J774A.1 cell line. The selectivity index (IS) was calculated by the ratio of MIC and CC50. The ten compounds tested had a MIC ranging from 4.0 to> 64.0 μM for strain H37Rv and MDR. With respect to CC50, the compounds had a concentration range ranging from 3.9 to 32.8 μM. Compound D15 exerted the best activity against the reference strain (H37Rv) and MDR strain (MDR 1576), however in the cytotoxicity test the compound that presented the best result was D10. Regarding the selectivity index, compounds A4 and A5 were the ones that obtained the best results even though they were below the ideal index. The compounds evaluated in this study showed moderate activity against Mtb and support the continuity of the study of 1,2-alkanediamine derivatives.Item Análise da atividade larvicida de hidrazidas contendo anéis do 1,2,4-oxadiazol e estudo das alterações morfo-histológicas em larvas de Aedes aegypti L. (Diptera, Culicidae)(2018-08-15) Nascimento, Jéssica da Silva; Oliveira, Lourinalda Luiza Dantas da Silva Selva de; Navarro, Daniela Maria do Amaral Ferraz; http://lattes.cnpq.br/6866049887225410; http://lattes.cnpq.br/7013867423178814The control of Aedes aegypti is now a major public health challenge because it’s responsible for important arboviruses such as: Dengue, Chikungunya, Zika and Urban Yellow Fever. In this work, we propose a study of the structure-activity relationship of 15 hydrazides against A. aegypti larvae, aiming to identify structural characteristics responsible for the larvicidal activity of the compounds. Fourth instar larvae were submitted to the compounds for 48 hours at different concentrations and then the LC50 was determined. Of the studied compounds, 9 presented considerable potential in the control of A. aegypti (LC50 <100ppm). The compound identied as HCBA presented greater larvicidal activity when compared to the others (LC50 = 20.63ppm) and aroused interest in understanding its mechanism of action. Larvae in the 4th instar were submitted to HCBA (20.63ppm), where they remained for 24 hours. The larvae that reached sublethal state were collected, xed in formoline, included in resin, sectioned, the blades stained by toluidine blue and analyzed by light microscopy. The morphohistological changes of the larvae submitted to the treatment were: high vacuolization in the cytoplasm and disorganization of the epithelium. These results demonstrate that the P-Cloro (HCBA) compound may be effective in controlling A. aegypti for promoting changes at the mesenteric level.