Manifiesto a favor de la enseñanza de la Geología

Manifest en defensa d'incloure la Geologia com a assignatura pròpia de la modalitat en el Batxillerat de Ciències

Passeig per l’invisible: itinerari químic per la ciutat de Girona = A walk through the invisible: a chemical journey through Girona

The presented itinerary covers eleven sites of the city of Girona that have been chosen for their interest from a chemical point of view. Girona is a city with chemistry, and this journey allowed student to see that chemistry is present everywhere, even in everyday life and not only in classrooms and laboratories. This approach aims to motivate students to discover something that had been invisible

"Reacciona... explota!", un taller per fomentar vocacions científiques

The workshop "React... explode!" is a project of science that shows the most attractive side of chemistry to pre-university students. It consists of carrying out recreational chemical experiments. Most students have more interest in the amazing and spectacular experiments which involve changes of colour, light, noise, smoke... The names of the experiments are very attractive: "The toilet’s monster", "The pharaoh’s snake", "The world of cold", "The termite reaction" ...

Micro- and nanostructuring of poly(ethylene-2,6-naphthalate) surfaces, for biomedical applications, using polymer replication techniques

Here we investigate the formation of superficial micro- and nanostructures in poly(ethylene-2,6-naphthalate) (PEN), with a view to their use in biomedical device applications, and compare its performance with a polymer commonly used for the fabrication of these devices, poly(methyl methacrylate) (PMMA). The PEN is found to replicate both micro- and nanostructures in its surface, albeit requiring more forceful replication conditions than PMMA, producing a slight increase in surface hydrophilicity. This ability to form micro/nanostructures, allied to biocompatibility and good optical transparency, suggests that PEN could be a useful material for production of, or for incorporation into, transparent devices for biomedical applications. Such devices will be able to be autoclaved, due to the polymer's high temperature stability, and will be useful for applications where forceful experimental conditions are required, due to a superior chemical resistance over PMMA.

Nivel de calidad de los medicamentos elaborados por los alumnos en el laboratorio de prácticas y de su control como producto acabado por parte de los mismos alumnos

Una de las prácticas de laboratorio de Tecnología Farmacéutica requiere la elaboración de comprimidos en la asignatura de Farmacia Galénica II siguiendo el mismo flujo de fabricación al empleado en la industria farmacéutica (pesada, tamización, mezclado, amasado, granulación, secado, mezclado y compresión). Estos comprimidos se analizan en la asignatura de Farmacia Galénica III (entre 6 y 12 meses más tarde) por los mismos alumnos según las directrices de la Real Farmacopea Española.En el trabajo se exponen gráficamente los resultados hallados y se comentan los principales puntos de mejora ya que el producto elaborado no es conforme en la mayoría de los casos (sólo alrededor del 50% de los productos elaborados por los alumnos podrían ser conformes, aún siendo un proceso validado). Realmente, la experiencia de los operadores es el punto más crítico que influye en los resultados de estos lotes de comprimidos, sobre todo en el laboratorio analítico. Esta hipótesis ha sido confirmada en lotes analizados por el personal cualificado del departamento de control de calidad del Servei de Desenvolupament del Medicament de la Facultat de Farmàcia de la Universitat de Barcelona, ya que en todos los casos los resultados obtenidos fueron más exactos, repetitivos y cercanos a los teóricos.

Repensando la formación inicial del profesorado para abordar el tratamiento a la diversidad cultural y lingüística en el aula = Rethinking initial teacher education for linguistic and cvltural diversity in the classroom

In recent decades, European educational systems are facing many challenges related to the treatment of cultural and linguistic diversity. The need to address this diversity requires new approaches to education; this in turn requires changes in the way we prepare teachers for the new reality they face in their classrooms. In this article we highlight some of the major problems that initial teacher training has to address in order to enable teachers to deal effectively, respectfully, and fairly with students whose linguistic and cultural background is different from their own. We also present several models for teacher education from Europe and North America based on clearly identified teacher competences for linguistic and cultural diversity

El plan de lengua y cohesión social en Catañunya: primeros datos de una investigación = Language and Social Cohesion Plan in Catalonia: Initial research data

Los programas de inmersión lingüística han constituido y constituyen dentro del Sistema Educativo catalánla principal forma para que el alumnado de lengua familiar no-catalana aprenda una nueva lengua, el catalán,sin que, en su proceso de aprendizaje, vea mermado ni el desarrollo de su propia lengua ni su rendimientoacadémico. El éxito de la inmersión lingüística en las décadas anteriores ha sido frecuentemente utilizado comouno de los argumentos orientativos para justificar la política lingüística que se sigue en la escolarización de lainfancia extranjera. Sin embargo, los resultados obtenidos por investigaciones recientes parece que no avalanempíricamente dicho argumento. Este artículo analiza dichos resultados y expone, a partir del Plan para laLengua y Cohesión Social puesto en marcha por el Departamento de Educación de la Generalitat de Cataluña,cuáles son los retos que se presentan a su Sistema Educativo dentro del nuevo marco que supone el aumento de ladiversidad cultural y lingüística en la actual sociedad catalana

Combined dielectrophoretic and impedance system for on-chip controlled bacteria concentration: Application to Escherichia coli

The present paper reports a bacteria autonomous controlled concentrator prototype with a user-friendly interface for bench-top applications. It is based on a micro-fluidic lab-on-a-chip and its associated custom instrumentation, which consists in a dielectrophoretic actuator, to pre-concentrate the sample, and an impedance analyser, to measure concentrated bacteria levels. The system is composed by a single micro-fluidic chamber with interdigitated electrodes and a instrumentation with custom electronics. The prototype is supported by a real-time platform connected to a remote computer, which automatically controls the system and displays impedance data used to monitor the status of bacteria accumulation on-chip. The system automates the whole concentrating operation. Performance has been studied for controlled volumes of Escherichia coli (E. coli) samples injected into the micro-fluidic chip at constant flow rate of 10 μL/min. A media conductivity correcting protocol has been developed, as the preliminary results showed distortion of the impedance analyser measurement produced by bacterial media conductivity variations through time. With the correcting protocol, the measured impedance values were related to the quantity of bacteria concentrated with a correlation of 0.988 and a coefficient of variation of 3.1%. Feasibility of E. coli on-chip automated concentration, using the miniaturized system, has been demonstrated. Furthermore, the impedance monitoring protocol had been adjusted and optimized, to handle changes in the electrical properties of the bacteria media over time.

Magnetic-field dependence of hole levels in self-assembled InGaAs quantum dots

Recent magnetotransport experiments of holes in InGaAs quantum dots [D. Reuter, P. Kailuweit, A. D. Wieck, U. Zeitler, O. Wibbelhoff, C. Meier, A. Lorke, and J. C. Maan, Phys. Rev. Lett. 94, 026808 (2005)] are interpreted by employing a multiband k¿p Hamiltonian, which considers the interaction between heavy hole and light hole subbands explicitly. No need of invoking an incomplete energy shell filling is required within this model. The crucial role we ascribe to the heavy hole-light hole interaction is further supported by one-band local-spin-density functional calculations, which show that Coulomb interactions do not induce any incomplete hole shell filling and therefore cannot account for the experimental magnetic field dispersion.

Electronic structure of few-electron concentric double quantum rings

The ground state structure of few-electron concentric double quantum rings is investigated within the local spin density approximation. Signatures of inter-ring coupling in the addition energy spectrum are identified and discussed. We show that the electronic configurations in these structures can be greatly modulated by the inter-ring distance: At short and long distances the low-lying electron states localize in the inner and outer rings, respectively, and the energy structure is essentially that of an isolated single quantum ring. However, at intermediate distances the electron states localized in the inner and the outer ring become quasidegenerate and a rather entangled, strongly-correlated system is formed.

Vertically coupled double quantum rings at zero magnetic field

Within local-spin-density functional theory, we have investigated the ¿dissociation¿ of few-electron circular vertical semiconductor double quantum ring artificial molecules at zero magnetic field as a function of interring distance. In a first step, the molecules are constituted by two identical quantum rings. When the rings are quantum mechanically strongly coupled, the electronic states are substantially delocalized, and the addition energy spectra of the artificial molecule resemble those of a single quantum ring in the few-electron limit. When the rings are quantum mechanically weakly coupled, the electronic states in the molecule are substantially localized in one ring or the other, although the rings can be electrostatically coupled. The effect of a slight mismatch introduced in the molecules from nominally identical quantum wells, or from changes in the inner radius of the constituent rings, induces localization by offsetting the energy levels in the quantum rings. This plays a crucial role in the appearance of the addition spectra as a function of coupling strength particularly in the weak coupling limit.

Reversible ferromagnetic switching in ZnO:(Co,Mn) powders

We report here on the magnetic properties of ZnO:Mn- and ZnO:Co-doped nanoparticles. We have found that the ferromagnetism of ZnO:Mn can be switched on and off by consecutive low-temperature annealings in O2 and N2, respectively, while the opposite phenomenology was observed for ZnO:Co. These results suggest that different defects (presumably n-type for ZnO:Co and p-type for ZnO:Mn) are required to induce a ferromagnetic coupling in each case. We will argue that ferromagnetism is likely to be restricted to a very thin, nanometric layer at the grain surface. These findings reveal and give insight into the dramatic relevance of surface effects to the occurrence of ferromagnetism in ZnO-doped oxides.