Solution-Based Assembly of Conjugated Polymers into Nanofibers for Organic Electronics

Solution-based crystallization of conjugated polymers offers a scalable and attractive route to develop hierarchical structures for electronic devices. The introduction of well-defined nucleation sites into metastable solutions provides a way to regulate the crystallization behavior, and therefore the morphology of the material. A crystallization method for generating metastable solutions of poly(3-hexylthiophene) (P3HT) was established. These metastable solutions allow P3HT to selectively crystallize into nanofibers (NFs) on graphene-coated surfaces. It was found that the crystallization kinetics is faster with increasing P3HT molecular weight and concentration. Through in situ atomic force microscopy, it was confirmed that NFs grow vertically in a face-on chain orientation (i.e., the π orbitals parallel to the substrate normal) from highly oriented pyrolytic graphite and graphene. Moreover, the P3HT crystal structure observed on the surface of graphene was identified to be the same one formed by solution crystallization. However, as confirmed by X-ray scattering and scanning electron microscopy the crystals transitioned from face-on to edge-on orientation (i.e., the π orbitals perpendicular to the substrate normal) as the film grew thicker. As determined by X-ray scattering. the initial face-on conformation was partially preserved by embedding the P3HT structures in an indene C60 bisadduct matrix when compared to pristine P3HT films. The resulting organic field effect transistors had hole mobilities (μ = 20 x 10-3 cm2 V-1 s-1) two orders of magnitude higher than the devices fabricated from spin casted P3HT (μ = 0.9 x 10-3 cm2 V-1 s-1). The solution-processable fabrication of electrodes and semiconductors is potentially scalable and amenable to roll-to-roll manufacturing

PROPUESTA DE UN SISTEMA DE RECOMENDACIÓN HIBRIDO SEMÁNTICO DE OBJETOS DE APRENDIZAJE EN EL ÁREA DE EDUCACIÓN AMBIENTAL BASADO EN LINKED DATA

Este artículo propone una arquitectura para la recomendación de objetos de aprendizaje en el área de Educación Ambiental utilizando el estándar LOM con el fin de representar recursos educativos en dicha área. La información necesaria para el proceso de recomendación será obtenida mediante la tecnología de datos enlazados en asocio con ontologías para recuperar los recursos desde repositorios de Objetos de Aprendizaje existentes en la Web. Paralelamente este sistema de recomendación hace uso de técnicas de filtrado basado en contenidos y colaborativos que favorece la selección de los objetos de acuerdo a los requerimientos del usuario dando como respuesta el material más adecuado al perfil del usuari

Comparative analysis of curricula of associate degree programs in marketing

This work is a comparative analysis of the curricula of associate degree programs in marketing offered by 8 Higher Education Institutions in Colombia registered in the information system of the National Ministry of Education of Colombia. Their study plans and references were compared to establish the courses of interest. Finally, professors in this field participated in a survey. The results show differences in terms of courses per field and number of courses, among other aspects

El Turismo creativo como dinamizador de las economías locales: Estudio de caso en una comunidad afrodescendiente

Creative tourism is currently emerging as a differential and alternative proposal for experiences to vindicate the cultural, environmental and artistic aspects, while the tourist simulates immersive interaction with social, cultural and natural landscapes. This article develops a case study with the village community of La Puerta, San Nicolás de quebrada seca, municipality of Sopetrán, Antioquia, in order to analyze the possibilities of tourism use, which can be accessed by the inhabitants of the Afro-descendant collective territory of the village of La Puerta, in Sopetrán, Antioquia, from the approach of the orange economy. For this purpose, a qualitative research method was applied, from a participatory and interactive methodological approach, with the predominance of techniques such as sociographic analysis and group discussion. Recognition of the modes of representation and territorial action of the community of La Puerta, in terms of the dynamization of social and community processes, which advocate for the protection of the ecosystemic patrimony, La Bramadora wetland. 2. Description of the process of insertion of a sustainable, creative and vindicating tourism, through conservation practices, such as bird watching, that stimulate and dynamize the development of the local economy. It is concluded that orange tourism is a dynamizer of local economic development par excellence, besides being one of the clearest bets in the process of economic recovery of the tourism sector in general.El turismo creativo emerge en la actualidad como una propuesta diferencial, alternativa y de cocreación para potenciar la vivencia de experiencias en función de reivindicar lo cultural, lo ambiental y lo artístico, al tiempo que el turista y el anfitrión se sumergen en una relación de interacción que les permite reconocerse, reunirse, desdibujarse, leerse y transitar desde la complicidad del saber por paisajes sociales, culturales y naturales. Se desarrolla en este artículo, un estudio de caso con la comunidad negra de La Puerta, corregimiento de San Nicolás de quebrada seca, municipio de Sopetrán, Antioquia, con el fin de analizar las posibilidades de aprovechamiento turístico, a las que pueden acceder los habitantes del territorio colectivo afrodescendiente de la vereda La Puerta, en Sopetrán, Antioquia, a partir del enfoque de la economía naranja. Para ello se aplicó un método de investigación cualitativo, desde un abordaje metodológico participativo e interactivo, con el predominio de técnicas como el análisis sociográfico y la discusión grupal. Se obtienen como resultados: 1. Reconocimiento de los modos de representación y actuación territorial propios de la comunidad de La Puerta, en función de la dinamización de procesos sociales y comunitarios, que propendan por la protección del patrimonio ecosistémico, humedal La Bramadora. 2. Descripción del proceso de inserción de un turismo sostenible, creativo y reivindicador, a través de prácticas de conservación, como el avistamiento de aves, que estimulen y dinamicen el desarrollo de la economía local. Se concluye que el turismo naranja es un dinamizador del desarrollo económico local por excelencia, además de ser unas de las apuestas más claras en el proceso de recuperación económica del sector turismo en general

The COVID-19 pandemic and its global effects on dental practice. An international survey

Objectives A multicentre survey was designed to evaluate the impact of COVID-19 outbreak on dental practice worldwide, estimate the COVID-19 related symptoms/signs, work attitudes and behaviour and the routine use of protective measures and personal protective equipment (PPE). Methods A global survey using a standardized questionnaire with research groups from 36 countries was designed. The questionnaire was developed and pretested during April 2020 and contained three domains: 1) personal data; 2) COVID-19 positive rate and symptoms/signs presumably related to the coronavirus; 3) working conditions and PPE adopted after the outbreak. Countries’ data were grouped by the country positive rate (CPR) during the survey period and by Gross-National-Income per capita. An ordinal multinomial logistic regression model was carried out with COVID-19 self-reported rate referred by dental professionals as dependent variable to assess the association with questionnaire items. Results A total of 52,491 questionnaires were returned with a male/female ratio of 0.63. Out of the total respondents, 7,859 dental professionals (15%) reported symptoms/signs compatible with COVID-19. More than half of the sample (n=27,818; 53%) stated to use FFP2/N95 masks, while 21,558 (41.07%) used eye protection. In the bivariate analysis, CPR and N95/FFP2 were significantly associated (OR=1.80 95%CI=1.60/2.82 and OR=5.20 95%CI=1.44/18.80, respectively), while Gross-National-Income was not statistically associated with CPR (OR=1.09 95%CI=0.97/1.60). The same significant associations were observed in the multivariate analysis. Conclusions Oral health service provision has not been significantly affected by COVID-19, although access to routine dental care was reduced due to country-specific temporary lockdown periods. While the dental profession has been identified at high-risk, the reported rates of COVID-19 for dental professionals were not significantly different to those reported for the general population in each country. These findings may help to better plan oral health care for future pandemic events

Análisis del déficit cuantitativo de vivienda en el municipio de el Espinal

En Colombia en promedio desde 2005 se forman al año 270 mil nuevos hogares que frente a una producción formal de vivienda de 150 mil unidades anuales no alcanza a cubrir la demanda actual. Aproximadamente 80 mil nuevos hogares no encuentran una oferta de vivienda apta. En el municipio de El Espinal Tolima existen 76.226 habitantes y 18.910 hogares de los cuales 2.232 no cuentan con vivienda digna propia, estas cifras aclaran el problema de carencia de vivienda que existe en el municipio actualmente. Debido a esta situación hemos elaborado un análisis del déficit habitacional partiendo de sus causas y efectos principales generados a la población. La investigación consta de ocho capítulos. En el primero se plantea la problemática con su respectiva descripción y se formulan algunas preguntas de investigación, en el segundo se presenta la justificación social del trabajo, en el tercero se plasman los objetivos a los cuales se dirige la investigación, en el cuarto capítulo se formula el marco de referencia conformado por el marco teórico, conceptual y legal. En el quinto capítulo de describe el diagnóstico del problema realizando la caracterización social de la población y de la zona afectada por el problema, en el sexto capítulo se describen los principales efectos que sociales que se generan en la población por la carencia de vivienda. En el séptimo capítulo se plantea las principales causas que ocasionan el déficit habitacional en la población. El octavo capítulo se describe las limitaciones del problema tomando como referencia el PBOT y el plan de desarrollo del municipio de El Espinal. Y finalmente se plantean las conclusiones y recomendaciones

Teacher's opinions regarding the MINEDUC'S english textbooks implementation and their actual use: a case study

Tesis (Profesor de Inglés para la Enseñanza Básica y Media y al grado académico de Licenciado en Educación)The main purpose of this research is to obtain information about the actual Use and Implementation of English textbooks provided by the Ministry of Education (MINEDUC) according to the opinions of four English Language teachers as a Foreign Language (EFL) who participated in this study. The goal is to show what teachers use the textbook for (Purpose), how often they use it (Frequency), how much they use it (Coverage) and whether they employ Complementary Materials or activities. The research site is a traditional public Secondary school located in Santiago, Chile. In order to carry out this investigation, we followed a qualitative methodology that consisted in open-ended interviews and observations. Each participant was interviewed and observed twice. Consequently, upon the analysis of interviews and classes observed, it became clear that teachers do not use the textbook as it is expected by the MINEDUC.El principal propósito de esta investigación es obtener información sobre el real uso e implementación de los libros de Inglés proporcionados por el Ministerio de Educación (MINEDUC) de acuerdo a las opiniones de los cuatro profesores de la lengua Inglesa como idioma extranjero que participaron en este estudio. La meta es mostrar para qué los profesores usan los textos (propósito), cuan a menudo lo usan (Frecuencia), cuanto usan de él (Cobertura) y si es que implementan Materiales o Actividades Complementarias. El sitio de la investigación es un colegio publico tradicional de Enseñanza Media ubicado en Santiago, Chile. De manera de llevar a cabo esta investigación, seguimos una metodología Cualitativa que consiste en entrevistas con preguntas abiertas y observaciones. Cada participante fue entrevistado y observado dos veces. En consecuencia, luego del análisis de las entrevistas y de las clases observadas, se hizo claro que los profesores no usan el texto como el MINEDUC espera

Selective Nucleation of Poly(3-hexyl thiophene) Nanofibers on Multilayer Graphene Substrates

We demonstrate that graphene surfaces provide highly selective nucleation of poly­(3-hexyl thiophene) (P3HT) nanofibers (NFs) from supersaturated solutions. Solvent conditions are identified that give rise to a wide hysteresis between crystallization and melting centered around room temperature, yielding metastable solutions that are stable against homogeneous nucleation for long periods of time but that allow for heterogeneous nucleation by graphene. Selective growth of P3HT crystals is found for multilayer graphene (MLG) supported on either Si or ITO substrates, with nucleation kinetics that are more rapid for MLG on Si but slower in both cases than for highly oriented pyrolytic graphite (HOPG). Although the NFs grow vertically from the substrate with face-on orientation of P3HT chains, we observe edge-on orientation in dried films, presumably due to capillary forces that cause collapse of the NFs onto the substrate during solvent evaporation

Iron and Copper Intracellular Chelation as an Anticancer Drug Strategy

A very promising direction in the development of anticancer drugs is inhibiting the molecular pathways that keep cancer cells alive and able to metastasize. Copper and iron are two essential metals that play significant roles in the rapid proliferation of cancer cells and several chelators have been studied to suppress the bioavailability of these metals in the cells. This review discusses the major contributions that Cu and Fe play in the progression and spreading of cancer and evaluates select Cu and Fe chelators that demonstrate great promise as anticancer drugs. Efforts to improve the cellular delivery, efficacy, and tumor responsiveness of these chelators are also presented including a transmetallation strategy for dual targeting of Cu and Fe. To elucidate the effectiveness and specificity of Cu and Fe chelators for treating cancer, analytical tools are described for measuring Cu and Fe levels and for tracking the metals in cells, tissue, and the body