Biodiesel production has gained a lot of attention due to its environmental benefits and production from renewable sources. Here, it is reported a magnetically recoverable catalyst of SrO immobilized on a CoFe 2 O 4 support (SrO/CoFe 2 O 4 ), which was efficiently applied for babassu oil transesterification and used up to four cycles without a significant activity loss. The stability and performance of the catalyst were analyzed considering the solvent used for its synthesis. Characterizations such as vibrating sample magnetometer (VSM), thermogravimetry (TG), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) were performed. The present study demonstrated that the catalyst has a strong magnetic response, which reflects the nature of the nanoparticles. For the first run, the material presented a yield of 96% when synthesized in acetone in a molar proportion of SrO/CoFe 2 O 4 of 5:1.
The advent of the COVID-19 pandemic brought changes to world education thanks to the adoption of measures of social isolation; the use of digital resources proved to be the most viable immediate solution for the continuity of teaching, but there are also problems such as the need for different didactic-pedagogical strategies wieldy of motivating students and teachers. The use of webinars as a complementary communication and guidance resource has proved to be a promising tool. Issues related to living with COVID-19 that combine their discussions with high school curriculum represent an important contribution to the construction of a contextualized knowledge base and, based on this observation, this study proposed to evaluate the presence of contents in the area of natural sciences and its technologies in COVID-19 webinars. A survey with the online video-sharing platform was carried out aiming to search for webinars on COVID-19 containing themes contained in the specific competences of natural sciences and their technologies for high school and how much these items were emphasized. The selection of the videos was made by analyzing what the title, keywords and their summary suggest. Biology, physics and chemistry have a great prominence and expert speakers with extensive experience in the area in which they work and great ability to expose the theme and the ability to clarify doubts have made webinars a valuable motivational approach to specific knowledge related to common national curriculum base - BNCC, as they involve community participation, in different contexts and using different digital technologies in conjunction with the contextual theme COVID-19.
New elements are needed to contribute to the idea of not reusing the materials, but rather improving their use, the massará for example is known in the region of Teresina-PI is a connecting material, of little consistency, easily disaggregatable (friable), containing white silica pebbles and of little utilização in the region. The interlocked concrete floor presents peculiar characteristics among which are those that configure it as a floor. The work analyzes through a mechanical strength and water absorption test the capacity that the interlocked concrete floor with the addition of massará in its composition offers in relation to bear load. Two traces with massará will be tried and then specimens will be molded to obtain the results of mechanical tests and characterization of the material in the laboratory. After the tests, it was observed the possibility of using it as components in the production of interlocked laying blocks used in construction companies of Teresina - PI.
Bearing in mind that the sand used as fine aggregate in the concrete manufactured in the City of Teresina comes entirely from the Poti and Parnaíba rivers, and the massara extracted from washing the material that gives rise to the pebble found in deposits. The present work aims at the mechanical characterization of the materials that make up the concrete, using the washed massará as fine aggregate, obeying the same proportions of aggregates, water and CP IV-32RS cement for conventional concrete. The particle size tests, cone trunk reduction and axial compression of cylindrical specimens were performed. After carrying out all the procedures, it was observed that the results achieved have similar compressive strength when compared to conventional concrete dosing, proving that it is possible to use the washed massará as an alternative of fine aggregate for the production of concrete.
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