Caracterização de filmes finos de Nb2O5 com propriedades eletrocrômicas

The sols for thin electrochromic coatings of Nb2O5 were obtained by synthesis of the niobium butoxide from BuONa and NbCl5. The ~300nm thick films were deposited by dip-coating technique from the alkoxide solution and calcined at 560ºC in O2 atmosphere during 3 hours. The particles size of niobium oxide (V) powder (~20mm) was obtained from x-ray diffraction using the Scherrer equation. The coatings were characterized by cyclic voltammetry and cronoamperommetry techniques. The spectral variation of the optical transmittance were determined in situ as a function of the cyclical potencial and memory effect. The insertion process of lithium is reversible and change the film color from transparent (T=80%) to dark blue (T=20%).

Afrontamiento de situaciones de hostilidad y desempeño de la función directiva. Planteamientos y reflexiones a raíz de una actividad de formación permanente de directivos de centros educativos de titularidad pública

The intervention in the organized conflicts and, particularly, the confrontation of hostile situations (based on the emotional alteration, the strain, the verbal aggressiveness, etc) is one of the aspects that worry the principals of the educative centres and, therefore, a main attention must be given to the initial and permanent training to have managing duties. Throughout the text we take some aspects into account in the development of these managing skills:a) we set the distinctive features; b) we answer to the dilemma about the existence of improvement possibilities; c) we state the need to star from the motivation and the active participation of the principals in their own personal development and, finally, d) we contribute with the design of a training activity to develop skills to confront hostile situations, addressed to the principals of primary and secondary schools, that was done in Girona, in November 2005

Análisis de barreras de transición a software libre y creación de un protocolo de implementación en centros educativos

A partir de la investigación desarrollada en el campo del software libre se pretende dar una visión de las cuestiones que existen a la hora de realizar una transición y migración a este tipo de software. Para ello se han estudiado los diferentes problemas existentes y todo el camino a recorrer para conseguir la implantación en centros educativos.

Análise por difração de raios x de filmes de óxidos cerâmicos compostos por IrO2/TiO2/CeO2

Independent of the sample form (powder or film), XRD analysis of Ir0,3Ti(0,7-x)Ce xO2, (nominal) mixtures, for x=0, shows the formation of a solid solution phase between IrO2 and TiO2, as well as the rutile phases of IrO2 and TiO2. The presence of the anatase phase of TiO2 is also confirmed. The introduction of 30 mol% CeO2 in the mixture reveals the presence of the CeO2 and Ce2O3 phases, besides the already mentioned ones, in the powder. In the film form, however, an amorphous phase is identified. When all of the TiO2 is substituded by CeO2, for both sample forms, the only phases found are IrO2, CeO2 and Ce2O3. This result suggests cerium oxides are not capable of forming solid solutions with either IrO2 or (Ir,Ti)O2 acting solely as a dispersant matrix for these phases. These results are consistent with the much higher electrochemically active surface area when CeO2 is introduced in the binary Ti/Ir0,3Ti0,7O2 mixture. It was possible to establish a relationship between the electrochemical stability of the supported films and their crystalline structure. The unexpected presence of TiO2 and Ti2O3 in the Ti/Ir0,3Ce0,7O2 (film sample) is attributed to oxidation of the Ti support during the calcination step.

Filmes de metal-hexacianoferrato: uma ferramenta em química analítica

Chemically modified electrodes based on hexacyanometalate films are presented as a tool in analytical chemistry. Use of amperometric sensors and/or biosensors based on the metal-hexacyanoferrate films is a tendency. This article reviews some applications of these films for analytical determination of both inorganic (e.g. As3+, S2O3(2-)) and organic (e.g. cysteine, hydrazine, ascorbic acid, gluthatione, glucose, etc.) compounds.

Filmes poliméricos ultrafinos produzidos pela técnica de automontagem: preparação, propriedades e aplicações

The self-assembly technique is a powerful tool to fabricate ultrathin films from organic compounds aiming at technological applications in molecular electronics. This relatively new approach allows molecularly flat films to be obtained on a simple and cheap fashion from various types of material, including polyelectrolytes, conducting polymers, dyes and proteins. The resulting multilayer films may be fabricated according to specific requirements since their structural and physical properties may be controlled at the molecular level. In this review we shall comment upon the evolution of preparation methods for ultrathin films, the process of adsorption and their main properties, as well as some examples of technological applications of layer-by-layer or self-assembled films.

La influencia del lenguaje cotidiano en el desarrollo de la escritura de los inmigrantes en los centros educativos

El objetivo de nuestra investigación es demostrar la importancia deluso de la lengua escolar fuera del entorno educativo y como este uso podría repercutir notablemente en el rendimiento académico del alumnado inmigrante. Según nuestra hipótesis, los alumnos inmigrantes que no practican en su vida cotidiana la lengua que se usa en los centros educativos realizarán más errores en la escritura que aquellos alumnos inmigrantes que sí practican dicho lenguaje fuera del entorno educativo. Las técnicas que emplearíamos para recopilar y clasificar la información serían cuestionarios y un corpus lingüístico. Los resultados que esperamos obtener son un número considerablemente alto de errores en la escritura por parte de los alumnos inmigrantes que no hablan el catalán en su entorno social no escolar, mientras que los alumnos autóctonos y los alumnos inmigrantes que sí practican el catalán fuera del ámbito educativo obtendrían mejores resultados. Estos resultados nos proporcionarían una evidencia más sobre la importancia del uso de las lenguas escolares en entornos no escolares.

Decomposição de precursores metalorgânicos: uma técnica química de obtenção de filmes finos

This review focus the more relevant foundations and applications of the Metallo-Organic Decomposition (MOD) technique, mainly within the last decade. The technique has grown significantly, mainly due to the good results concerning the preparation of multicomponent oxide systems with composition, structural and morphologic control, in a relatively simple way. This opened new opportunities to obtain materials with well-defined electrical and optical properties.

Interrogantes educativos desde la sociedad del conocimiento

La Sociedad del conocimiento y la forma como hoy gestionamos la información se han traducido en la introducción de las TICs en el sistema educativo, incorporando muchas veces la terminología (Escuela 2.0, aprendizaje digital, ) pero no los auténticos cambios que esas tecnologías han provocado en la Sociedad y, por ende, en nuestros estudiantes. En este artículo se plantean 9 de los temas más relevantes que son objeto de discusión social: la autoridad del experto cuestionada por la inteligencia colectiva, la superficialidad del conocimiento denunciada por Carr, la inestabilidad de los documentos y de sus contenidos sujetos a cambio en cualquier momento, la inabarcabilidad de la información que hace "imposible incluso al especialista estar al día", los derechos del autor y el propio concepto de autor en la era de la "segunda oralidad", la democracia informativa como alternativa al "cuarto poder", el acceso global superando fronteras, el respeto a la privacidad y la identidad digital. Frente a esos temas la escuela o la universidad introducen las tecnologías sin alterar su modelo ni sus prácticas. El objetivo final de este texto es invitar a los educadores a reflexionar sobre su práctica docente.

Interrogantes educativos desde la sociedad del conocimiento

La Sociedad del conocimiento y la forma como hoy gestionamos la información se han traducido en la introducción de las TICs en el sistema educativo, incorporando muchas veces la terminología (Escuela 2.0, aprendizaje digital, ) pero no los auténticos cambios que esas tecnologías han provocado en la Sociedad y, por ende, en nuestros estudiantes. En este artículo se plantean 9 de los temas más relevantes que son objeto de discusión social: la autoridad del experto cuestionada por la inteligencia colectiva, la superficialidad del conocimiento denunciada por Carr, la inestabilidad de los documentos y de sus contenidos sujetos a cambio en cualquier momento, la inabarcabilidad de la información que hace "imposible incluso al especialista estar al día", los derechos del autor y el propio concepto de autor en la era de la "segunda oralidad", la democracia informativa como alternativa al "cuarto poder", el acceso global superando fronteras, el respeto a la privacidad y la identidad digital. Frente a esos temas la escuela o la universidad introducen las tecnologías sin alterar su modelo ni sus prácticas. El objetivo final de este texto es invitar a los educadores a reflexionar sobre su práctica docente.

Formação e caracterização óptica de filmes automontados de POMA/PPV

A study is presented of the formation and optical properties of polymeric heterostructures from poly(p-phenylene vinylene) (PPV) and poly(o-methoxyaniline) (POMA) produced via the self-assembly technique. POMA layers were obtained in a non self-limiting process from its emeraldine salt, semiconducting form in HCl solution. Thermal conversion of PPV was performed at low temperatures with the substitution of the counter-ion Cl in the PPV precursor by a long sulfonic chain, the dodecylbenzenesulfonate (DBS) ion. The optical properties of PPV films converted in this way are not affected by POMA, which can be used as transparent electrode of PPV luminescent devices.

Fotocromismo em filmes finos de óxidos de tungstênio de diferentes composições

Tungsten oxide thin films with three different compositions were deposited by reactive sputtering in an oxygen-argon plasma. In a system composed of a home made photochemical reactor coupled with an optic fiber spectrophotometer, the photochromic effect was studied in these oxide films as function of UV irradiation time, in ethanol, methanol and formaldehyde atmospheres. It was observed that the photochromic efficiency depends on the vapor chemical nature where the film is irradiated as well as the film composition. Kinetic analysis suggest that two kinds of optical absorption centers should respond by the photochromic effect in these films, one generated at film surface and other inside it, which one presenting a different time constant.

Filmes de titânio-silício preparados por "spin" e "dip-coating"

The conditions for the preparation of luminescent materials, consisting of Eu3+ ions entrapped in a titanium matrix, in the forma of a thin film, using the sol-gel process, are described. The films were obtained from sols prepared with TEOS and TEOT, in the presence of acetylacetone as the hidrolysis-retarding agent, using the dip-coating and spin-coating techniques. The influence of these techniques on the films based on titanium and silicon are presented. The Eu3+ was used as a luminescent probe. The films have been characterized by luminescence, reflection and transmittance. The thickness of the films could be related to the preparation procedure. Transparent thin films have been prepared by dip-coating technique.

Filmes delgados luminescentes obtidos a partir de hidroxicarbonatos de ítrio ativados por európio ou térbio

These films were obtained by dip coating. Parameters like dislocation velocity; number of deposits, suspension concentration, and number of deposits followed or not by heat treatment between each deposit and calcination temperature were evaluated for establishing the best homogeneity. The obtained films were characterized in terms of their morphology, optical quality and photoluminescence by scanning electron microscopy (SEM), UV-vis absorption spectrophotometry and luminescence spectroscopy, respectively. The morphologic and luminescent characteristics showed dip coating as good laboratory technique for development of thin films for optical applications.

Desenvolvimento de um sistema automatizado para a fabricação de filmes automontados

In this technical note, we describe the construction of a low-cost computer controlled device for layer-by-layer film fabrication. The software allows to control multiple material deposition, washing and drying steps and the time for each operation. To test the device, we produced and characterized self-assembled films of conductive polymers by alternating poly(o-methoxyaniline) (POMA) and poly(3-thiophene acetic acid) (PTAA) via the layer-by-layer technique.