The Round Table : University, knowledge and apprenticeship

El text que es presenta a continuació és una resposta possible al repte d’experimentar amb l’escriptura en el territori acadèmic. En aquest cas es tracta de comunicar, per la via de la narració lliure, l’informe d’una recerca. En aquest cas, es tracta de la lectura-escolta d’un programa de radio imaginari en el que es debaten temes setmanalment de la mà de tres protagonistes, que són convidats al programa, i dels seus col·laboradors habituals. Durant la narració s’ha tractat de mantenir un equilibri entre els requisits del gènere i els del material propi de la recerca, intentant passar per cadascun dels apartats propis d’un informe de recerca, utilitzant un llenguatge més planer, una estructura més de tipus conversacional i alhora imprimint un ritme narratiu que remeti al llenguatge radiofònic. D’altra banda, pel què fa al material que s’ha pres com a base per a la construcció de la narració, correspon a un modest treball de recerca elaborat durant el curs 2004-2005 en el marc d’una assignatura de lliure elecció, d’introducció al món de la recerca qualitativa en Psicologia Social, a la Universitat Autònoma de Barcelona. Els objectius del treball consistien en conèixer les explicacions sobre el valor que s’assigna al coneixement universitari entre els estudiants de la UAB, en el context universitari i en la societat en general, i els processos d’aprenentatge que s’hi despleguen. El treball de camp va consistir en la realització de tres entrevistes semi-estructurades a estudiants de la UAB, la transcripció de les quals ha estat adaptada per a construir les seves intervencions en la narració.This article is an experiment in academic writing: I shall give a research report in free narrative. The narrative vehicle is an (imaginary) radio programme in which three presenters, and their customary guests, discuss topics on a weekly basis. I shall try to keep a balance between the needs of narration on the one hand, and the requirements of a research report on the other. The language will be plainer, and the structure will be more conversational. The topic of the report is a study (originally done as part of the qualitative methods course at the Universitat Autònoma de Barcelona) of students' perceptions of academic knowledge and academic learning. The data were three semi-structured interviews, whose transcripts have been adapted so as better to serve the requirements of the narration

Metal Additive Distribution in TiO2 and SnO2 Semiconductor Gas Sensor Nanostructured Materials

Recently, there has been an increasing interest in the electronics world for those aspects related to semiconducting gas sensor (SGS) materials. In view of the increasingly strict legal limits for pollutant gas emissions, there is a great interest in developing high performance gas sensors for applications such as controlling air pollution and exhaust gases. In this way, semiconductor gas sensors offer good advantages with respect to other gas sensor devices (such as spectroscopic and optic systems), due to their simple implementation, low cost and good reliability for real-time control systems. In the present work, we have been especially interested in the study of the different ways of metal additive distribution in the most common SGS materials used nowadays and furthermore in the physical and chemical sensing properties they can achieve

Generic Battery Model based on a Parametric Implementation

Batteries are a common element used in many electronic applications. Therefore, the analysis and simulation of these applications requires a battery model in order to validate the behavior of the whole system. Since batteries are based on different technologies, a modeling approach valid for any technology is a potential good alternative. Since there are similarities among the different technologies, it is possible to address the modeling of batteries as generic energy storage elements with particular differences. This work presents a battery model valid for different technologies based on a parametric implementation

Engineering surface states of hematite based photoanodes for boosting photoelectrochemical water splitting

Hematite-based photoanodes are promising candidates for photoelectrochemical water splitting. However, the performance of pristine hematite semiconductors is unsatisfactory due to charge recombination occurring at different interfaces: Back contact, bulk and semiconductor/electrolyte interfaces. Increasing efforts have been focused on enhancing the performance of hematite based photoanodes via nanostructure control, doping, heterojunction construction, and surface modification with a secondary semiconductor or an oxygen evolution electrocatalyst. Most of the previous studies attributed the enhanced PEC water splitting performance to the changes in the donor density via doping, the formation of type II heterojunction via a secondary semiconductor coating and the improved water oxidation kinetics via coating oxygen evolution electrocatalysts. However, the role of surface states presented at the semiconductor/electrolyte interfaces of hematite-based photoanodes has been overlooked in previous investigations, which virtually play a critical role in determining the photoelectrochemical water oxidation process. In this review, we summarize the recent progress of various techniques employed for the detection of surface states of hematite photoanodes and highlight the important role of modifying surface states in the development of high performance hematite based photoanodes for photoelectrochemical water splitting application. The challenges and future prospects in the study of hematite based photoanodes are also discussed

Erosion caused by propeller jets in a low energy harbour basin

This is an Accepted Manuscript of an article published by Taylor & Francis Group in Journal of Hydraulic Research on January, 2017, available online at: http://www.tandfonline.com/10.1080/00221686.2016.1252801Field data of a harbour basin are compared with analytical formulations for predicting maximum scouring depth due to propeller jets. Spatial data analysis of seven-year biannual bathymetries quantifies the evolution of the scouring hole along with the sedimentation process within a harbour basin. The maximum scouring depth is found to be of the order of the propeller diameter with a maximum scouring rate within the first six months of docking manoeuvring. Three of the analysed expressions yielded realistic results while observed discrepancies between the theoretical predictions and field data are related to scaling factors. The outcomes of this analysis can be extrapolated to other harbours to improve their management. The obtained results highlight the importance of field data in developing combined physical and numerical models.Peer ReviewedPostprint (author's final draft

Nucleation and growth of GaN nanorods on Si (111) surfaces by plasma-assisted molecular beam epitaxy - The influence of Si- and Mg-doping

The self-assembled growth of GaN nanorods on Si (111) substrates by plasma-assisted molecular beam epitaxy under nitrogen-rich conditions is investigated. An amorphous silicon nitride layer is formed in the initial stage of growth that prevents the formation of a GaN wetting layer. The nucleation time was found to be strongly influenced by the substrate temperature and was more than 30 min for the applied growth conditions. The observed tapering and reduced length of silicon-doped nanorods is explained by enhanced nucleation on nonpolar facets and proves Ga-adatom diffusion on nanorod sidewalls as one contribution to the axial growth. The presence of Mg leads to an increased radial growth rate with a simultaneous decrease of the nanorod length and reduces the nucleation time for high Mg concentrations

Metal-organic framework-derived single atom catalysts for electrocatalytic reduction of carbon dioxide to C1 products

Electrochemical carbon dioxide reduction reaction (eCO RR) is an efficient strategy to relieve global environmental and energy issues by converting excess CO from the atmosphere to value-added products. Single-atom catalysts (SACs) derived from metal-organic frameworks (MOF), which feature unique active sites and adjustable structures, are emerging as extraordinary materials for eCO RR. By modulating the MOF precursors and their fabrication strategy, MOF-derived SACs with specific-site coordination configuration have been recently designed for the conversion of CO to targeted products. In the first part of this review, MOF synthesis routes to afford well-dispersed SACs along with the respective synthesis strategy have been systematically reviewed, and typical examples for each strategy have been discussed. Compared with traditional M-N active sites, SACs with regulated coordination structures have been rapidly developed for eCO RR. Secondly, the relationship between regulation of the coordination environment of the central metal atoms, including asymmetrical M-N sites, heteroatom doped M-N sites, and dual-metal active sites (M-M sites), and their respective catalytic performance has been systematically discussed. Finally, the challenges and future research directions for the application of SACs derived from MOFs for eCO RR have been proposed

Manejo de cuencas en Argentina : conceptos, diagnóstico y aspectos institucionales

Fil: Vich, Alberto I. J.Fil: Cobos, Daniel R..Fil: Lenzano, Luis E.

Desenvolupament d’una xarxa autònoma per a bombeig d’aigua mitjançant energia fotovoltaica

El projecte tracta sobre el desenvolupament d’una xarxa per al bombeig d’aigua fent ús d’energia fotovoltaica. En el document es pot trobar tota la informació teòrica relativa a aquest tipus d’instal·lacions, els càlculs necessaris per dimensionar el sistema a partir d’un indret suposat amb una demanda d’aigua suposada, els criteris d’elecció dels components que conformen la xarxa, i alguns aspectes d’interès com el marc legal que l’envolta o l’impacte ambiental que pot causar. També, es realitza un estudi econòmic on s’analitza el pressupost de la implementació de la instal·lació partint des de zero, i es compara la solució fotovoltaica davant d’altres alternatives, com ara, l’eòlica, l’electricitat de la xarxa, o amb el preu d’una factura de subministrament d’aigua. L’energia fotovoltaica com a font d’energia per a un sistema d’aquest tipus és una opció viable per la constància del sol a la zona d’implementació, la possibilitat d’emmagatzemar aigua a un dipòsit per satisfer el consum els dies de baixa radiació i pel baix impacte ambiental. Resulta ser la més barata perquè l’equip fotovoltaic és més econòmic que les altres opcions, i en cas de fer la instal·lació partint des de zero i tenint en compte el preu tarifari del subministrament d’aigua, la inversió inicial es recupera abans del termini de la seva vida útil, que és de 25 anys

Metal island film-based structures for sensing using spectrophotometry and ellipsometry

Metal island films (MIF) are good candidates for sensors due to the strong sensitivity of the localised surface plasmon resonance to the environment refractive index. The strong near field enhancement in the vicinity of the island surface can be even higher if a metal layer (ML) is placed close to a MIF. Structures containing MIF with and without ML are prepared and sensitivities of spectrophotometric and ellipsometric features of the measurements are compared. It is shown that simple MIF is preferable for ellipsometry-based sensing and the one including ML in the case of spectrophotometric measurements