Recent trends in metals extraction

After near 70 years of practical usage, solvent extraction is a perfectly mastered technique of separation, widely used on an industrial scale for the separation of metals mainly from raw materials. However, currently, in the era of depleting natural resources and increasingly less accessible deposits, environmental restrictions, etc., an increasing interest, both from social and economical constrains, is being directed at the extraction of metals from the secondary sources (such as batteries, electronic scrap). In many cases, solvent extraction, due to its operational characteristics, can be considered as the Best Available Technology for the purpose of separating multielemental metal solutions. This paper provides a brief overview of past achievements and present scenario of solvent extraction investigations and developments, describing some recently commissioned solvent extraction plants, whereas the Skorpion Zinc plant (Namibia) for zinc extraction from raw materials and caesium removal from radioactive High Level Wastes (HLWs) are told over in detail as case studies. The paper also presents some proposals for the use of liquid-liquid extraction to separate metal ions from secondary sources (e.g. cobalt from industrial waste streams). The review highlights the emerging use of ionic liquids as new extractants for metals, providing an insight into this exciting research field. Despite its detractors, solvent extraction has entered in force into XXI century as a leading separation technology for metals.Peer Reviewe

Facial identity and emotional expression as predictors during economic decisions

Two sources of information most relevant to guide social decision making are the cooperative tendencies associated with different people and their facial emotional displays. This electrophysiological experiment aimed to study how the use of personal identity and emotional expressions as cues impacts different stages of face processing and their potential isolated or interactive processing. Participants played a modified trust game with 8 different alleged partners, and in separate blocks either the identity or the emotions carried information regarding potential trial outcomes (win or loss). Behaviorally, participants were faster to make decisions based on identity compared to emotional expressions. Also, ignored (nonpredictive) emotions interfered with decisions based on identity in trials where these sources of information conflicted. Electrophysiological results showed that expectations based on emotions modulated processing earlier in time than those based on identity. Whereas emotion modulated the central N1 and VPP potentials, identity judgments heightened the amplitude of the N2 and P3b. In addition, the conflict that ignored emotions generated was reflected on the N170 and P3b potentials. Overall, our results indicate that using identity or emotional cues to predict cooperation tendencies recruits dissociable neural circuits from an early point in time, and that both sources of information generate early and late interactive patterns

Optimisation of pyrolysis parameters for CF composites with respect to mechanical properties of recovered fibers

The aerospace/aeronautics, energy and automotive industries are the primary users of advanced polymer composites in structural components. Increasing number of those components are reaching End of Life and will be disposed in landfills, which is currently the most common option worldwide. However, environmental concerns and consequent demands from society drives industries to search for ways to repurpose decommissioned composite structures. The most beneficial would be to reuse composites and/or their constituents after the service life. Thermal recycling is a method to recover costly fibers and lower the environmental impact. The objective of this work is to optimize conditions of pyrolysis of carbon fiber (CF) composite aiming to recover reinforcement with highest mechanical properties. The specimens for this study were cut (15x30x3mm) from epoxy/CF laminate with randomly oriented fiber. To identify the best conditions, the pyrolysis is performed at different thermal cycles under various environments with mass loss monitored throughout the experiments. The conditions of the reference experiment are based on data from literature (550C for 30 min under nitrogen atmosphere, with oxidation in air for 60 min, see Fig. 1). Additionally, pyrolysis was performed under different temperatures and environments: variation of temperature on first stage, dipping specimens in hot furnace instead of gradual heating, changing conditions of oxidation. In order to select pyrolysis process with most optimal conditions the surface of the recovered fibres is investigated by means of optical microscopy and scanning electron microscopy. The mechanical properties of fibers are evaluated and compared to virgin fibers

Direct steam generation in parabolic trough collectors

Existing commercial parabolic trough power plants use thermal oil as a heat transfer fluid, with working temperatures in the region of 400ºC. In order to achieve more efficient generating systems, a second generation of parabolic troughs that operate at temperatures higher than 400ºC is being developed. One possibility, Abengoa Solar is assessing, it is the use of direct steam generation (DSG) inside parabolic troughs in order to achieve higher temperatures; the first stage heating up to 450 ºC and the second stage heating up to 550 ºC. There is, however, a certain degree of complexity in the use of DSG technology that has resulted in it not yet being utilized in commercial plant designs. Due to the presence of saturated steam inside the parallel loops the required control system is more complex, particularly during transitory periods of radiation. Also the higher operating pressures and temperatures in the solar field mean that the receiver tubes and interconnections between collectors are very critical components. For this reason, typical systems utilize an intermediate fluid for energy transfer. In order to overcome these challenges, Abengoa Solar has built a demonstration plant of 8 MWht. The plant is composed of an evaporator field with three parallel loops and a superheater field with two loops in order to work at 85 bar and 450ºC. The demonstration plant has been operated and evaluated for one year. During this test period, the following have been evaluated and validated: An innovative control strategy system that guarantees the stability of the plant even under transient conditions. Receiver tube design able to achieve 450ºC, analyzing the mechanical behavior, optical performance, and heat losses. Different configurations of interconnections between collectors with ball joints and flexible rotation joints. A theoretical model has been developed for commercial scale DSG plants and validated with experimental data obtained from the demonstration plant

Fiber sensors for the high-speed railway environment

Specialty Optical Fibers 2014, Barcelona, Spain, 27–31 July 2014We review some recent work on fiber-optic sensors for the high-speed railway environment. In particular, we show convenient fiber-optic solutions for rail and wheel monitoring, perimeter security and catenary protection in changeover section

Metodologies per a la coresponsabilitat en l’aprenentatge universitari

L’Espai Europeu d’Educació Superior ha propiciat un replantejament metodològic basat en el desenvolupament de competències que permet formular noves propostes d’estil docent universitari. En aquest article plantegem un model metodològic pròxim als principis del constructivisme social i del pensament complex, aplicable a un mòdul dels estudis de grau en Educació Infantil i en Educació Primària, analitzant diferents estratègies didàctiques utilitzades per a facilitar l’aprenentatge dels estudiants. Les diverses propostes metodològiques tenen, com a denominador comú,les particularitats següents: totes elles estan centrades en l’alumne, dinamitzen diferents àmbits competencials i afavoreixen la coresponsabilitat entre professor i estudiant en el procés d’aprenentatge. Els resultats d’un estudi fet durant el curs 2008-2009 sobre la percepció dels estudiants en relació a metodologies afins a les proposades,ens ha servit per a ratificar la pertinença de la majoria d’estratègies i incorporar-les al Pla docent del mòdul Societat, Família i Escola I

Econometric modelling

[EN] The current economic environment, together with the low scores obtained by our students in recent years,makes it necessary to incorporate new teaching methods. In this sense, econometric modelling providesa unique opportunity o ering to the student with the basic tools to address the study of Econometricsin a deeper and novel way. In this article, this teaching method is described, presenting also an examplebased on a recent study carried out by two students of the Degree of Economics. Likewise, the successof this method is evaluated quantitatively in terms of academic performance. The results con rm ourinitial idea that the greater involvement of the student, as well as the need for a more complete knowledgeof the subject, suppose a stimulus for the study of this subject. As evidence of this, we show how thosestudents who opted for the method we propose here obtained higher quali cations than those that chosethe traditional method.[ES] El entorno económico actual, así como las bajas calificaciones obtenidas por nuestros/as estudiantes en los últimos años, hace necesaria la incorporación a la docencia de nuevos métodos de enseñanza más acordes con esta realidad. En este sentido, la modelización econométrica proporciona una oportunidad única al proveer al/ a la alumno/a de las herramientas básicas para abordar de forma profunda y novedosa el estudio de la Econometría. En el presente artículo, se describe ese método de enseñanza, presentando además un ejemplo del mismo basado en un estudio realizado por dos alumnos del Grado de Economía. Asimismo, se evalúa cuantitativamente el éxito de este método en términos de rendimientos académicos. Los resultados obtenidos confirman nuestra idea inicial de que la mayor implicación del/ de la estudiante, así como la necesidad de un conocimiento más completo de la materia, supone un estímulo para el estudio de esta asignatura. Como prueba de ello, mostramos cómo aquellos/as estudiantes que optaron por el método que proponemos aquí obtuvieron mayores calificaciones a aquellos/as que eligieron el método de enseñanza tradicional.Alguacil Marí, M.; Jiménez Fernández, E. (2017). La modelización en la Econometría. Modelling in Science Education and Learning. 10(2):239-250. doi:10.4995/msel.2017.7690SWORD239250102Granger C. W. J. (1990). Modelling Economic Series. Oxford University Press.Garcia Raffi L.M., Sánchez-Pérez J.V. y Sánchez Pérez E.A. (1999). Introducción de las técnicas de modelización para el estudio de la física y de las matemáticas en los cursos de las carreras técnicas. Ense-anza de las Ciencias 17(1), 119-129.Launer R.L., Wilkinson G.N. (1979). Robustness in the strategy of scientic model building. in Robustness in Statistics. Academic Press: New York.Ramanathan R. (2002). Introductory econometrics with applications. 5a edición. Harcourt College Publishers