High Density Single Crystalline GaN Nanodot Arrays Fabricated Using Template-Assisted Selective Growth

High density, uniform GaN nanodot arrays with controllable size have been synthesized by using template-assisted selective growth. The GaN nanodots with average diameter 40nm, 80nm and 120nm were selectively grown by metalorganic chemical vapor deposition (MOCVD) on a nano-patterned SiO2/GaN template. The nanoporous SiO2 on GaN surface was created by inductively coupled plasma etching (ICP) using anodic aluminum oxide (AAO) template as a mask. This selective regrowth results in highly crystalline GaN nanodots confirmed by high resolution transmission electron microscopy. The narrow size distribution and uniform spatial position of the nanoscale dots offer potential advantages over self-assembled dots grown by the Stranski–Krastanow mode.

High Indium Concentration InGaN/GaN Grown on Sapphire Substrate by MOCVD

The InGaN system provides the opportunity to fabricate light emitting devices over the whole visible and ultraviolet spectrum due to band-gap energies E[subscript g] varying between 3.42 eV for GaN and 1.89 eV for InN. However, high In content in InGaN layers will result in a significant degradation of the crystalline quality of the epitaxial layers. In addition, unlike other III-V compound semiconductors, the ratio of gallium to indium incorporated in InGaN is in general not a simple function of the metal atomic flux ratio, f[subscript Ga]/f[subscript In]. Instead, In incorporation is complicated by the tendency of gallium to incorporate preferentially and excess In to form metallic droplets on the growth surface. This phenomenon can definitely affect the In distribution in the InGaN system. Scanning electron microscopy, room temperature photoluminescence, and X-ray diffraction techniques have been used to characterize InGaN layer grown on InN and InGaN buffers. The growth was done on c-plane sapphire by MOCVD. Results showed that green emission was obtained which indicates a relatively high In incorporation.

Core-Shell Assisted Bimetallic Assembly of Pt and Ru Nanoparticles by DNA Hybridization

We have discovered that the current protocols to assemble Au nanoparticles based on DNA hybridization do not work well with the small metal nanoparticles (e.g. 5 nm Au, 3.6 nm Pt and 3.2 nm Ru particles). Further investigations revealed the presence of strong interaction between the oligonucleotide backbone and the surface of the small metal nanoparticles. The oligonucleotides in this case are recumbent on the particle surface and are therefore not optimally oriented for hybridization. The nonspecific adsorption of oligonucleotides on small metal nanoparticles must be overcome before DNA hybridization can be accepted as a general assembly method. Two methods have been suggested as possible solutions to this problem. One is based on the use of stabilizer molecules which compete with the oligonucleotides for adsorption on the metal nanoparticle surface. Unfortunately, the reported success of this approach in small Au nanoparticles (using K₂BSPP) and Au films (using 6-mercapto-1-hexanol) could not be extended to the assembly of Pt and Ru nanoparticles by DNA hybridization. The second approach is to simply use larger metal particles. Indeed most reports on the DNA hybridization induced assembly of Au nanoparticles have made use of relatively large particles (>10 nm), hinting at a weaker non-specific interaction between the oligonucleotides and large Au nanoparticles. However, most current methods of nanoparticle synthesis are optimized to produce metal nanoparticles only within a narrow size range. We find that core-shell nanoparticles formed by the seeded growth method may be used to artificially enlarge the size of the metal particles to reduce the nonspecific binding of oligonucleotides. We demonstrate herein a core-shell assisted growth method to assemble Pt and Ru nanoparticles by DNA hybridization. This method involves firstly synthesizing approximately 16 nm core-shell Ag-Pt and 21 nm core-shell Au-Ru nanoparticles from 9.6 nm Ag seeds and 17.2 nm Au seeds respectively by the seed-mediated growth method. The core-shell nanoparticles were then functionalized by complementary thiolated oligonucleotides followed by aging in 0.2 M PBS buffer for 6 hours. The DNA hybridization induced bimetallic assembly of Pt and Ru nanoparticles could then be carried out in 0.3 M PBS buffer for 10 hours.

Corner Flows in Free Liquid Films

A lubrication-flow model for a free film in a corner is presented. The model, written in the hyperbolic coordinate system ξ = x² – y², η = 2xy, applies to films that are thin in the η direction. The lubrication approximation yields two coupled evolution equations for the film thickness and the velocity field which, to lowest order, describes plug flow in the hyperbolic coordinates. A free film in a corner evolving under surface tension and gravity is investigated. The rate of thinning of a free film is compared to that of a film evolving over a solid substrate. Viscous shear and normal stresses are both captured in the model and are computed for the entire flow domain. It is shown that normal stress dominates over shear stress in the far field, while shear stress dominates close to the corner.

Films sobre la historia de Cataluña.

Resumen en catalán

Aprendiendo a aprender : Learning trough films.

Material pensado para su utilización tanto dentro como fuera del aula (autoaprendizaje), que se presenta en dos tomos. En el primero se incluyen guías, tanto para el profesorado como para el alumnado, para el visionado de cuatro películas en lengua inglesa, disponibles en el mercado. El objeto de estas guías es evaluar el contenido de las películas y así contribuir a mejorar el aprendizaje de la lengua inglesa. Con la misma finalidad, en el segundo tomo se presentan 25 escenas cortas en las que se trabajan los diferentes aspectos de la lengua. Cada secuencia va precedida de una ficha técnica en la que se detalla la película de la que se ha extraído, un título descriptivo, duración y localización en la cinta y todos los aspectos metodológicos para su elección -conceptos, estrategias, actitudes y objetivos-. Se incluyen tres fichas-tipo de evaluación para el alumnado: My work, Video agenda y My teacher reports; y una para el profesorado: Student record. Con ellas se pretende establecer un canal de comunicación abierto entre profesorado y alumnado que optimice el proceso de enseñanza-aprendizaje y favorezca una enseñanza más personal e individualizada.

Linatakalam : serie de TV patrocinada por el GAN para la Alianza de Civilizaciones (ONU).

Nominación Mejor Documental Premios Mestre Mateo 2006. Versiones en árabe, francés, castellano y gallego

Films etnográficos : la construcción audiovisual de las otras culturas.

El artículo forma parte del monográfico de la revista: Educación y comunicación para la cooperación y el desarrollo. Resumen de la propia revista

Representaciones identitarias del ecuatoriano en tres films nacionales

La siguiente investigación analiza a lo largo de su desarrollo cómo se construyen las representaciones identitarias del ecuatoriano, en los personajes principales de tres filmes nacionales: Zuquillo Exprés, A tus Espaldas y Prometeo Deportado. Además de definir los elementos socioculturales, audiovisuales, clichés y estereotipos que caracterizan a un personaje principal. Es por ello que el análisis inicia con la indagación de conceptos claves de diferentes autores que permitan establecer el punto de partida para la definición de: identidad, representación, ecuatorianidad, personaje, cine y estereotipo. Una vez entendido la concepción de cada concepto, la investigación da cara a las observaciones de las películas en sí. Primero en conocer el contexto en el que se desarrollan, la época, ambientación e historia y contexto para después identificar los personajes centrales que serán parte del estudio. Conocer cuáles son sus rasgos, tanto físicos, como culturales, de donde provienen, sus gustos, manera de hablar, lugares a los que frecuentan y hasta qué tipo de comida suelen consumir. Así como también identificar en su conjunto los rasgos generales, que en este caso prima la religión y migración como rasgos un tanto repetitivos. Es entonces que la investigación pasa al análisis pasa a la interpretación de las perspectivas con las que se han combinado identidad y representación en cada uno de los personajes y los tipos con los que han sido construidos a través de la visión del director. Es así que se define una lista de estereotipos y elementos con los que se caracteriza la personalidad de los personajes centrales de cada film.

Phenolic contents of lettuce, strawberry, raspberry, and blueberry crops cultivated under plastic films varying in ultraviolet transparency

The levels of health-related phytochemicals were determined in lettuce leaf and in strawberry, raspberry and blueberry fruits grown in near-commercial conditions under plastic films of three different UV transparencies. In the red lettuce Lollo Rosso, total phenolics, anthocyanin, luteolin and quercetin levels were all raised by changing from a UV blocking film to a film of low UV transparency, and to a film of high UV transparency. The related green lettuce, Lollo Biondo, cultivated under the same conditions, showed virtually no phytochemical responses to the same variation in UV levels. Overall, the phenolic levels of strawberries, raspberries, and blueberries were unresponsive to the UV transparency of the plastic film under which the crops were grown. The significance of these findings is discussed in relation to the nutritional quality of soft fruit and salad crops which are increasingly being grown commercially under plastic tunnels.