Estrategias de funcionalización de grafeno para el desarrollo de nanocompuestos de matriz termoplástica

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Departamento de Química Inorgánica. Fecha de lectura:29-03-2019El objetivo principal de esta tesis es el desarrollo de nanocompuestos poliméricos multifuncionales basados en grafeno, con potencial aplicación en sectores como el de la automoción y el aeronáutico. Se investigan tres polímeros termoplásticos con propiedades muy diferentes pero todos de gran relevancia industrial: un elastómero termoplástico, poli(estireno-b-etileno-cobutileno- b-estireno) (SEBS), una poliolefina, polipropileno isotáctico (iPP), y un polímero de altas prestaciones, poli(éter éter cetona) (PEEK). Con la incorporación del grafeno se pretende obtener materiales con mejor estabilidad térmica y propiedades mecánicas, y que presenten conductividad eléctrica. En esta tesis se desarrollan estrategias de funcionalización del grafeno específicas para cada matriz termoplástica y se preparan nanocompuestos poliméricos empleando grafeno modificado y sin modificar como carga. Se estudia la influencia que la modificación química ejerce sobre la morfología de fases del nanocompuesto y sobre la estructura cristalina del material resultante. Del mismo modo, se evalúa la estabilidad térmica de cada uno de los sistemas obtenidos y se determinan sus propiedades mecánicas y eléctricas, para establecer la efectividad de la modificación química en la obtención de nanocompuestos con mejores propiedades. Los resultados indican mejoras en la dispersión del grafeno modificado con cadenas poliméricas cortas de naturaleza similar a la de la matriz polimérica objetivo. Esto da lugar, generalmente, a nanocompuestos con superior estabilidad térmica y mejores propiedades mecánicas y eléctricas en comparación con el empleo de grafeno sin funcionalizar. Además, algunos de los nanocompuestos de iPP y PEEK se exploraran para el desarrollo de materiales compuestos con jerarquía de refuerzo, donde se combina tejido continuo de fibra de carbono (refuerzo en la microescala) y grafeno (refuerzo en la nanoescala). Con la incorporación de grafeno al sistema multicapa convencional, es decir, fibra de carbono/polímero, se pretende mejorar las propiedades interlaminares del sistema, que son las principales causantes de su fallo mecánico. No obstante, la preparación de sistemas multicapa donde se combinan refuerzos en la micro- y nano-escala es muy complejo, ya que no solo hay que conjugar factores de dispersión e interacción de la nanocarga, sino que también se ven influenciados por factores como la viscosidad e impregnación de la fibra, siendo estos últimos de especial dificultad en el caso de emplear matrices termoplásticas.The main objective of the thesis research is the development of advanced polymer nanocomposites based on graphene, with the aim of producing multifunctional materials suitable to be used in demanding sectors such as the automotive and the aeronautic industry. Three thermoplastic polymer matrixes of important relevance for the industry are selected: a thermoplastic elastomer, poly(styrene-b-ethylene-co-butylene-b-styrene) (SEBS), a polyolefin, isotactic polypropylene (iPP) and a high performance polymer, poly(ether ether ketone) (PEEK). Graphene incorporation is aimed to simultaneously improve both thermal stability and mechanical properties, and also to provide the new material with electrical conductivity. In this thesis, specific strategies for graphene functionalization are developed according to the targeted polymer matrix and polymer nanocomposites with graphene or modified graphene are prepared. The aim is to investigate the influence that graphene modification exerts on nanocomposite phase morphology and on the crystalline morphology of the resulting material. Furthermore, the thermal stability of each system is assessed and their mechanical and electrical properties are determined, with the aim of evaluating the suitability of the graphene chemical modification to develop nanocomposites with enhanced properties. The results suggest that modifying graphene with short polymer chains similar in nature to those of the targeted polymer matrix improve its dispersion. As a result, nanocomposites with superior thermal stability and better mechanical and electrical properties than in the case of the non-functionalized graphene are typically produced. In addition, some iPP and PEEK nanocomposites are explored in the preparation of composite materials hierarchically reinforced with carbon fibre fabric (microscale reinforcement) and graphene (nanoscale reinforcement). The purpose of incorporating graphene to the conventional composite (fibre reinforced polymer composite) is to improve its interlaminar properties, which are the main cause of catastrophic failure in this type of systems. Nonetheless, the preparation of composite materials where micro- and nano-scaled reinforcements are combined is very complex, since not only the filler dispersion and its interaction with the matrix need to be considered, but additional parameters such as matrix viscosity and fibre impregnation are of special relevance, especially in the case of thermoplastic matrices.Financiada por el Ministerio de Economía, Industria y Competitividad (MAT2013-47898-C2-2-R

Catalytic performance of CuO/Ce0.8Zr0.2O2 loaded onto SiC-DPF in NOx-assisted combustion of diesel soot

This work presents a comparative study between the catalytic performance of the 2% CuO/ceria-zirconia powder catalyst and the same catalyst supported on silicon carbide DPF (Diesel Particulate Filter) towards NO oxidation reaction and soot combustion reaction. The ceria-zirconia catalyst was prepared by the co-precipitation method and 2 wt% copper was incorporated by the incipient wetness impregnation method. The catalyst was incorporated onto the ceramic support using a simple and organic solvent-free procedure by a simply dipping the DPF into an aqueous solution of the catalyst. The powder catalyst has been characterized using N2 adsorption at −196 °C, XRD and Raman Spectroscopy; whereas the catalytic coating morphology has been evaluated by SEM and the mechanical stability by an adherence test. Both catalyst configurations were tested for NO oxidation to NO2 and for soot combustion under NOx/O2. The results revealed that incorporation of the very active copper/ceria-zirconia catalyst onto SiC-DPF has been successfully achieved by a simple coating procedure. Furthermore, the catalytic coating has shown suitable mechanical, chemical and thermal stability. A satisfactory catalytic performance of the catalytic-coated filter was reached towards the NO oxidation reaction. Moreover, it was proved that the catalytic coating is stable and the corresponding coated DPF can be reused for several cycles of NO oxidation without a significant decrease in its activity. Finally, it was verified that the loose-contact mode is a good choice to simulate the catalytic performance of this active phase in a real diesel particulate filter.The authors gratefully acknowledge the financial support of Generalitat Valenciana (PROMETEOII/2014/010 project), the Spanish Ministry of Economy and Competitiveness (CTQ2012-30703 project, UE-FEDER funding). S.Q.D. wishes to thank VIDI-University of Alicante her Master Thesis Grant

Comparative study on the cello’s initiation methods used in Andalusian music conservatories: implications for teachers

Este estudio analiza diferentes métodos de enseñanza-aprendizaje de violoncello en conservatorios de música de Andalucía (España) y las implicaciones educativas que estos puedan tener en el proceso de enseñanza-aprendizaje de este instrumento, especialmente para el profesorado. Se ha utilizado una metodología de tipo descriptivo, mediante análisis de contenido. Como instrumento de recogida de datos se ha usado una ficha adaptada de Garde, Gustems y Calderón (2015), compuesta por 41 item. Se llevó a cabo una comparación de los diferentes métodos de iniciación al violonchelo empleados en los conservatorios participantes, en función de cuatros dimensiones de análisis: aspectos didáctico-metodológicos, parámetros físicos, aspectos psicológicos y sensibilización musical. Sobre la primera dimensión, los resultados muestran una divergencia entre los textos analizados respecto al rol del profesor en el proceso didáctico. Con relación a los parámetros físicos, se observa una escasez de contenidos en los diferentes métodos que no ayuda a prevenir posibles problemas de salud y de interpretación en el alumnado novel. Aparece también poca atención respecto al desarrollo de aspectos psicológicos (concentración y memoria). Por último, los manuales analizados muestran especial atención hacia los aspectos vinculados a la dimensión sensibilización musical (afinación, sentido rítmico y hábitos de estudio). Los resultados de este estudio ponen de relieve la importancia de la formación del profesorado en metodologías de enseñanza activas, creativas y contemporáneas, ya que la mayoría de los métodos analizados deja en manos de los docentes aspectos de alta relevancia en el desarrollo musical del alumnado.</jats:p

Atender las tensiones educativas en la formación inicial del profesorado: la indagación narrativa como práctica pedagógica

El presente artículo da cuenta de la experiencia vivida junto a nuestras estudiantes en el devenir de un curso universitario. Un devenir en el que las tensiones y resistencias con la materia, crearon la necesidad de imaginar otros modos desde los que atender el saber disciplinar. Así, el propósito de este trabajo de doble: a) explorar cómo, desde nuestro quehacer docente, nos hacemos cargo de la asignatura y de las tensiones vividas en el aula; y b) profundizar caminos de construcción de saberes que nos han facilitado la creación de condiciones para que en la formación inicial del profesorado sea posible movilizar las tensiones entre lo institucionalizado, lo recogido en el plan docente y, lo que vivimos en tanto que saber encarnado en las aulas. Para ello, desplegamos un camino metodológico en el que la indagación narrativa, como fenómeno y método (Clandinin y Connelly, 2000), nos permite pensar y volver a la experiencia educativa para hallar lugares y maneras desde las que poner en tensión los saberes co-compuestos junto a nuestras estudiantes. Es la práctica de poner en tensión aquella en la que el saber de la experiencia toma significatividad (Contreras y Pérez de Lara, 2010). Un saber de la experiencia que remite a un modo, siempre en movimiento, de preguntarnos por el sentido de lo vivido y de lo que significa y supone la relación educativa

La hora del Power Cuento

El objetivo de esta comunicación es describir el trabajo realizado con alumnos de educación infantil en dos centros de la localidad de Torre Pacheco. Tomando como referencia un cuento relacionado con los centros de interés de las unidades didácticas del aula, se ha elaborado un plan de actividades concreto. Algunas de estas actividades están diseñadas con el programa Power Point. Con ello se pretende fomentar la motivación del alumnado, desarrollar y estimular el lenguaje en todos sus niveles e iniciar a los alumnos en el uso de las TIC. En este caso el cuento elegido ha sido; “Los animales de la granja” para trabajar la unidad didáctica de los animales de granja. Este material quedará en el centro a disposición del resto de compañeros, para que sirva de guía en la realización de materiales similares

El uso del análisis institucional como recurso pedagógico en la formación docente universitaria

Este artículo presenta un proceso de investigación desarrollado en una Casa de Acogida (CA) de niños en situación de riesgo social en una provincia de Argentina, que es utilizado como recurso pedagógico en la formación universitaria de los nuevos maestros y educadores en la Universidad de Barcelona. intención de acercarlos a la indagación socioeducativa. El abordaje de lo institucional en el proceso de investigación que se les presenta se realizó desde la perspectiva teórica-metodológica del análisis institucional, pero, teniendo en cuenta la complejidad que encierra toda institución, el proceso fue interactivo, adaptable y creciente con las aportaciones de distintos autores que permitieron entrelazar una red de significados que contribuyeron a la comprensión de lo que el proceso investigativo iba originando, moviendo y desencadenando tanto en quienes investigaban como con los participantes de la investigación. El proyecto de investigación se desarrolló durante seis meses por un equipo de investigadoras, y su desarrollo y resultados contribuyeron positivamente en los saberes de los estudiantes quienes se aproximaron al ámbito educativo con el desarrollo del pensamiento crítico, reconociendo la alteridad que los rodea e intervenir en consecuencia. Aquí presentamos, principalmente, la perspectiva y metodología del análisis institucional en investigación y cómo ha sido llevada a la formación como recurso pedagógico

Evaluation of the Analgesic Efficacy of a Bioelectronic Device in Non-Specific Chronic Low Back Pain with Neuropathic Component. A Randomized Trial

Low energy pulsed electromagnetic signals (PEMS) therapy, in the field of bioelectronics, has been suggested as a promising analgesic therapy with special interest in treating conditions with poor response to pharmacotherapy. This study evaluated the effectiveness of PEMS therapy on the treatment of chronic low back pain patients with a neuropathic component. A group of 64 individuals with such condition was allocated to a 2-week treatment period (10 twenty-minute sessions on consecutive days) with an active PEMS therapy device or an inactive device in random order. The pain was assessed on a visual analog scale, and the functional status was assessed using the SF-12 questionnaire. The visual analog scale scores were lower after treatment than at baseline but only in the group treated with the active device. According to the DN4 score, neuropathic pain decreased in both experimental groups with respect to baseline, but this was only significant for the group treated with the active device. Similarly, an improvement in the SF-12 and Medical Outcomes Study (MOS) sleep scale components was reported. The study demonstrated that low-energy PEMS therapy was efficient in reducing pain and improving function in chronic low back pain patients with a neuropathic component

COVID Obesity: A One-Year Narrative Review

On 11 March 2020, coronavirus disease 2019 (COVID-19) was declared a pandemic by the World Health Organization (WHO). This study focuses on a narrative review about the illness during the first year of the pandemic in relation to obesity. Databases were used to search studies published up to 8 December 2020. In total, 4430 articles and other scientific literature were found, and 24 articles were included in this one-year narrative review. The mean BMI value of severe COVID-19 patients ranged from 24.5 to 33.4 kg/m2, versus <18.5 to 24.3 kg/m2 for non-severe patients. Articles using the terms obesity or overweight without indicating the BMI value in these patients were common, but this is not useful, as the anthropometric parameters, when not defined by this index, are confusing due to the classification being different in the West compared to among Asian and Korean criteria-based adults. We proposed a new term, called COVID obesity, to define the importance of this anthropometric parameter, among others, in relation with this pandemic

Study of the kinematics of rigid body using the sliding vectors' theory

[EN] The sliding vector theory is a powerful tool for the study of the three parts of Classical Mechanics in vectorial formulation: Kinematics, Statics and Dynamics. Due to the great importance of the Vector Mechanics for their technical applications in engineering, this part of the Physics is studied in the first years of Engineering Degrees, as a fundamental topic included in the subjects of Physics. The rigid body model is the solid under study in Vectorial Mechanics. Firstly, in Kinematics, its movement is studied regardless of its causes. Afterward, in Dynamics, its motion is related with the forces that cause it. Finally, in Statics, its equilibrium under forces acting is studied. Rigid body definition as a set of particles in which the distance between them remains constant induces its equiproyectivity velocity field property. The study of elementary movements of rigid body: Translation, Rotation and System of Rotations allow the formal expression of the velocity field. Taken into account that the equiproyectivity property is characteristic of the moment field of a sliding vectors system, the formal expression of the velocity field of a rigid body coincides with the aforementioned moment field. It can be derived that the instantaneous velocity field of a rigid body can be formulated as the moment field of a sliding vector system. In this case, the rotation vectors act as sliding vectors, and its velocities as the moments at the points of the rigid solid. In this paper, the theory that allows the study of the velocity field by analogy with the moment field of a sliding vectors system is developed. By means of the rotation and the velocity vectors at a given point, the classification of any the movement of rigid body will be done. Moreover, the plane and spherical movements will defined, which provide any kind of movement of the solid if they are overlapped properly.Llopis Cosin, JV.; Rubio Michavila, C.; Gasque Albalate, M.; Quiles Casado, SDLS. (2013). Study of the kinematics of rigid body using the sliding vectors' theory. En ICERI2013 Proceedings. IATED-INT Assoc Technology Education& Development. 1136-1143. http://hdl.handle.net/10251/51426S1136114

ARE WE READY FOR A CHRONIC CRISIS? REFLECTIONS ON THE EXPERIENCE OF TEACHING DURING CONFINEMENT

[EN] The lockdown period that started on March 2020 due to the COVID-19 pandemic was a big challenge for students and teachers. Technology made the continuation of the teaching easier, and it also allowed teachers to keep the contact both with colleagues and with students. New teaching and evaluation methodologies and new coordination and cooperation systems had to be quickly implemented. Our previous experience in flipped teaching, active methodologies and validation of online exams, helped us to tackle the transition from face-to-face to fully online teaching. The experience was satisfactory for the theory classes, but some problems in the laboratory classes have emerged. After that, right now, some extra work is needed to overcome these difficulties considering that maybe the situation would become chronic. Once that we got over the shock of the first moment, the question is whether the resilience mechanisms will remain, and if the hybrid teaching (face-to-face & online) can replace effectively face-to-face teaching for a long time. In this work we present the students¿ opinion on this question. The analysis has been performed at the School of Design Engineering of the Universitat Politècnica de València, in different courses of physics of several engineering degrees (all of them, first academic year courses). One example of good practice during confinement was the weekly coordination meetings between teachers of the same course and between teachers of physics courses in different degrees. Another one was the online exams, taking advantage of the automatic correction tests, and including images of the documents written by the students for later review. The academic results were comparable to those of a normal course and student and teachers' surveys were conducted to know their opinion. The good performance during this new situation was due to the collaboration, patience, understanding and trust of the students and teachers that was created in those moments of crisis. Students' opinion on the online teaching during their lockdown was positive. This work shows this students' opinion on the methodology used during the lockdown, and the process from previous flipped teaching methodologies experiences to a completely online teaching. At the same time, the students' opinion on the laboratory practices was also analysed. Finally, this work also shows the reflection of the involved teachers on the additional workload and on the capacity for cooperation and communication between them, during the lockdown period and the subsequent year. After gathering the opinion of teachers and students, we can conclude that the situation of the pandemic has been addressed with reasonable success. Performance of students is not affected, the theoretical classes have been developed normally, while the practical classes seem to need some changes to be adapted to the new situation as far as possible. Given that this situation persists, it is useful to carry out this type of study to be able to adapt teaching to future circumstances.Authors would like to thank the Institute of Education Sciences of the Universitat Politècnica de València (Spain) for supporting the Teaching Innovation Group e-MACAFI and for the financial support through PIME Project PIME/2018/B25 and PIME Project PIME/2018/B26Tort-Ausina, I.; Vidaurre, A.; Riera Guasp, J.; Gamiz-Gonzalez, M.; Meseguer Dueñas, JM.; Gómez-Tejedor, J.; Quiles Casado, SDLS.... (2021). ARE WE READY FOR A CHRONIC CRISIS? REFLECTIONS ON THE EXPERIENCE OF TEACHING DURING CONFINEMENT. IATED Academy. 359-367. https://doi.org/10.21125/edulearn.2021.0117S35936