Cacao mucilage exudates (CMEs), byproducts of cacao beans fermentation, are effluents rich in sugars and low-molecular-weight organic acids. In this study, we utilized CMEs to formulate culture media ...for the biosynthesis of polyhydroxyalkanoates (PHAs) using a native
Bacillus megaterium
strain (
B2
). Our investigation followed the adaptation process of
B2
to the CMEs-based media, and we closely monitored the development of the microorganism in terms of consumption of acids and sugars. Upon successful adaptation to the CMEs-based media, we transferred the strain to a 4-L batch bioreactor to evaluate the impact of operational variables on PHAs production. We examined the microorganisms’ yield, productivity, and growth kinetics using the CME-based media. Our results showed a product yield of 0.98 g PHA/g carbon source, with an accumulation percentage of 57% and a productivity increase of 33% compared to PHA produced from residual glycerol using the same microorganism. The biopolymer's structure was confirmed to be of a polyhydroxybutyrate homopolymer (PHB) type using various molecular characterization techniques, including Matrix-Assisted Laser Desorption/Ionization mass spectrometry (MALDI-TOF-MS), infrared spectroscopy (IR), elemental composition (EC), ultraviolet–visible spectroscopy (UV–VIS), and thermal analysis (TGA, DSC).
Graphical Abstract
Abstract
This article describes the understanding of motion by active students taking Newtonian physics for engineering, supported by active learning, during the pandemic due to COVID-19; in ...addition, an unsupervised predictive model of learning achievement was constructed from variables identified using the principal component analysis technique on the responses. the instrument used is the modified test of understanding graphs-kinematics comprehension. students from two universities in Bogotá, Colombia participated. The results show a lower level of accuracy in students in remote face-to-face mode, compared to the reference group of physical presence; by way of reflection, the forced educational experiment implies resizing the teaching activity in the teaching and learning of movement.
Esta investigación se centra en la percepción de los estudiantes sobre la influencia de una plataforma digital en la interacción y aprendizaje social en un contexto educación híbrido en una ...universidad pública de Colombia. Se adopta un enfoque cuantitativo y descriptivo, mediate un estudio de campo con 131 estudiantes inscritos en una Facultad de Educación. Se utiliza un cuestionario basado en encuestas. Los resultados revelan que el 95.6% de los estudiantes accede a redes sociales, pero solo el 79.60% las emplea con fines académicos. Se evidencia que más del 50% aprecia el apoyo docente, aunque indicaron la necesidad de mejorar aspectos como la retroalimentación y el tiempo de respuesta. En cuanto a las metodologías didácticas, el 51.90% y 39.20% de los estudiantes consideran adecuados los enfoques basados en proyectos y en problemas, respectivamente. En conclusión, se destaca el papel transformador de la plataforma educativa en la experiencia educativa, promoviendo un aprendizaje colaborativo y social.
The work presents a didactic proposal on the use of concept maps, for the understanding of mechanical physics. A didactic intervention based on Ausubel's theory was applied with the following ...activities: design, implementation and application of workshops based on real physical situations, where the elaboration of concept maps is the central axis, under the quantitative paradigm of interpretative level and action research method. The informants were 43 tenth grade students from a public educational institution located in the Department of Norte de Santander, Colombia. The results obtained showed that the use of concept maps as a didactic intervention favoured the significant learning of classical mechanics concepts. It was evident that the participating students achieved reflective analysis about the resolution of problems about the concepts of mechanics.
In this study, the electro-oxidation reaction of ethanol over Pd–Cu supported on Cu porphyrin (TPPCu) was investigated. The catalyst was synthesized using the microwave-assisted polyol method and ...physicochemically characterized by XRD, XPS, SEM, EDS, TEM, EDAX, UV–Vis, FTIR, and RBS. A Cu-enriched catalyst with Cu
3
Pd, Pd,Cu, and TPPCu phases was identified using XRD and XPS. However, according to the RBS results, the catalytic surface was enriched with Pd, indicating that the interaction between TPPCu and Pd–Cu allowed the presence of Pd on the surface, thus enhancing the catalytic response of the material. This synthesis prevented the deprotonation of porphyrin on the electrocatalyst, as confirmed by XPS analysis. Electrochemical studies based on cyclic voltammetry and electrochemical impedance spectroscopy were used to investigate the response of the catalyst to variations in the scan rate and increasing ethanol concentration. The electrochemical response of PdCu/TPPCu improved with an increasing number of cycles, indicating improved mass transport, thus improving its electrochemical response and tolerance to CO contamination. This catalyst exhibited a high electroactive surface area of 49.4 m
2
/g, which could be related to the presence of TPPCu as a support. The behavior of the catalyst on the anode of a fuel cell fed with ethanol, bioethanol, and bioethanol residues was evaluated.
Graphical Abstract
This research is part of a line of research in education that aims to determine the degree of influence that affects have on the study of basic sciences that usually generate high rates of academic ...loss or repetition in school environments. The aim of this research was to analyze the system of beliefs that a group of students had about themselves as physics students, about physics as a discipline, about the physics teacher and his or her teaching practices, and about the importance of this area of knowledge in their social environment. To achieve this objective, a private educational institution is intentionally selected, with a home in San José de Cúcuta, Colombia, characterized by good results in the Saber 11 state tests. The informants were all students enrolled in 2019 in grades nine and eleven. A questionnaire was designed consisting of 36 items evaluated by means of a Likert scale with five levels of response. The results attested to the internal consistency and validity of the questionnaire. Subsequently, a complete characterization of the informants was carried out, allowing us to discover that the women in the sample have a better attitude and abilities in the study of physics. Finally, a factorial analysis was carried out in order to verify whether the opinions of the respondents fit into the four categories of beliefs considered by the researchers. Six factors were identified that explain 80% of the common variance, highlighting within them the beliefs that the student has about himself and his relationship with the teacher as the main factor explaining 41% of the variance.
The objective of this article is to identify the competencies of students studying the subject of natural sciences - physics at the high school level, in accordance with the curricular guidelines of ...the Ministerio de Educación Nacional de Colombia. Methodologically, it was based on a quantitative design, using a student perception survey. The results show, from the students' point of view, that the teachers have knowledge of their discipline, but the follow-up and improvement of their pedagogical practice at the curricular, didactic and evaluation levels is questioned. It is questioned that the processes related to research and the scientific method are not linked to their classes, so that the students' level of competences is not the ideal one according to what is established from the curricular orientations at a national level.
Abstract
Science education should promote the development of competent students in science and develop their interest in science; however, although the role and relevance of science within society is ...evident; the interest towards it is not conscious, being the negative attitudes of the students the main problem in the teaching of physics, which translates into a deficient knowledge and lack of scientific vocation. This report aims to diagnose the attitudes of students in high school physics courses. The study was developed through a non-experimental, descriptive research design, obtained from the application of a Likert scale that evaluates attitudes towards physics, adapted and validated to the context of students in an educational institution in Colombia. The results indicate that the attitudes of the students are slightly favorable, which is an empirical precedent to continue with the studies on attitudes towards physic. This should be considered to enhance the learning processes in these students, especially for those who have their first approach to physical concepts and give importance to attitudes when teaching.
El presente artículo analiza el impacto en el rendimiento académico y las opiniones de los estudiantes en la implementación del modelo aula invertida en un programa de formación de docentes de ...matemáticas. El horizonte metodológico se enmarca en la investigación educativa empírica con el diseño teórico de los entornos de aprendizaje. Se aplicó una prueba pretest-postest y un cuestionario escala Likert. La muestra estuvo conformada por 42 estudiantes de un programa de pregrado de una universidad pública en Norte de Santander (Colombia). Los resultados evidencian que el rendimiento académico de los estudiantes en los que se utilizó esta metodología tiende a mejorar en comparación con los estudiantes que utilizan el método tradicional. Las opiniones de los estudiantes sobre esta estrategia fueron en su mayoría positivas, lo que demostró la preferencia por este escenario innovador. Este trabajo da un paso hacia la conceptualización del modelo aula invertida como un esfuerzo para transformar los cursos tradicionales.
Abstract
Several mathematical concepts have application in physics; this paper reports the results of a pedagogical investigation based on the methodology known as didactic engineering, which has ...been proposed with the aim of improving the skills exhibited by a group of eleventh grade students from a private institution in the interpretation of kinematic graphs. The concept of the slope of the straight line and how this mathematical concept can represent velocity or acceleration according to the variables considered in the kinematics graph provided was enhanced in the pedagogical intervention. This methodology offers a process of internal validation, after comparing the results obtained in a knowledge test at two different points in time (pre-test and post-test). The results allowed us to identify improvements in all students in terms of basic kinematics graph interpretation skills, and a group of students stood out by advancing in more complex reasoning and interpretation processes. These results contribute to the improvement of the pedagogical practices of Physics teachers at secondary and middle school levels, making them more competent when they enter higher education.
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