Esta pesquisa teve como objetivo analisar as percepções de estudantes do terceiro ano do ensino médio em cidades do brejo paraibano acerca do processo de aprendizagem na disciplina de Química. Para tanto, compreende-se que o aprendizado de Química é fundamental para o entendimento de vários fenômenos e transformações que ocorrem no nosso cotidiano, possibilitando a relação teoria e prática de vários conceitos químicos. Assim, para que esse tipo de aprendizagem ocorra, é necessário que o ensino possibilite ao educando ir além da memorização de conteúdo, pois o processo de ensino e aprendizagem deve acontecer dentro de uma perspectiva construtiva. Para construção dos dados, realizamos um estudo de natureza quantitativa, interpretativa e descritiva, com quantificação de dados. O levantamento de dados ocorreu por meio da aplicação de um questionário composto por perguntas objetivas. A pesquisa foi realizada em quatro municípios situados no brejo paraibano, sendo desenvolvidas em escolas estaduais dos municípios de Arara, Areia, Bananeiras e Solânea. Os resultados alcançados apontam a necessidade de mudanças metodológicas e didáticas que possam aprimorar cada vez mais a aprendizagem de conceitos químicos. Ademais, destacamos a necessidade do uso de diferentes abordagens de ensino, tais como o uso da contextualização e da experimentação como estratégias fundamentais para o melhor aprendizado dos discentes. Compreende-se que o ensino apoiado, a partir dessas perspectivas possibilita uma maior motivação dos estudantes em aprender Química, pois além de explorar conteúdos relacionados ao seu cotidiano, tornar-se-ão cidadãos capazes de desenvolver o senso crítico e reflexivo.

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Summary Biodiesel is an alternative renewable fuel in the world energy matrix, originating from animal fats and vegetable oils from grains, such as the castor bean cultivated by family farmers in the Brazilian semiarid region. However, the production of biodiesel has some disadvantages. For example, it is difficult to use the same types of oil/fat all year round. In addition, the use of methanol in the biodiesel synthesis and agitation process results in a high consumption of energy. Given this background, this article proposes an alternative biodiesel synthesis using castor oil and peanut oil mixtures, ultrasound‐assisted in an ethylic route. The experimental conditions were optimized utilizing a Box‐Behnken design. The response variable was a biodiesel yield. In this work, it was possible to reduce the ratio of alcohol to oil and thus reduce the energy consumption and increase the mass yield. This permitted the generation of biofuel with lower production costs. Finally, the response surface methodology leads to operational conditions more suitable for the production of biodiesel. In this work, the best conditions were obtained using 0.50% catalyst concentration, 50/50 castor:peanut oil rate, and 5:1 alcohol:oil ratio. These were moderate and suitable conditions for the synthesis of biodiesel in comparison with the works found in the literature, reaching a high yield of 97.93%.

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Chemically degraded soils are found all over the world. Fertilization is an essential agronomic technique for recovering fertility and productivity in these areas. In this context, the objective was to recover the productive capacity of a degraded Red Yellow Argisol, grown with Brachiaria decumbens Stapf, in the presence of mineral fertilization with increasing amounts of nitrogen, evaluating the production of plant mass, plant height, tillering and water consumption. The experiment was conducted in a screened shelter and humidity control, according to a completely randomized experimental design. The treatments were organized in a factorial scheme, 6 treatments (without fertilization, 0, 30, 60, 90, 120 of nitrogen; 80 and 50, phosphorus and potassium for all treatments in g vase-1, respectively) corresponding to the amount of fertilizer applied in Kg ha-1, 4 cuts (performed every 30 days, starting 45 days after planting) and 5 repetitions. When fertilizing with 120 Kg ha-1 of nitrogen, it was obtained increase in fresh (655%) and dry (685%) mass when compared to the phytomasses of the treatment without fertilization, there was also an increase in the number of effective tillers and plant height, as the amounts of nitrogen applied increased in the soil. The maximum amount of nitrogen to be applied to the soil, in order to produce phytomass of B. decumbens in the condition of chemical degradation of the soil, obtained in the work was 120 Kg ha-1. In addition, the work allowed us to conclude that fertilization is an inexpensive and very important technique to recover the productive capacity of forage in the micro region of Brejo Paraibano, Northeast Brazil.