Epilog: Cajal’s unique and legitimated school

Santiago Ramón y Cajal is recognized as the founder of modern neuroscience, his discoveries representing the fundamental pillars of our current understanding of the nervous system. As Cajal’s career spanned a critical period in Spanish history, he witnessed strong social demands for progress in culture, education, and science. Indeed, the life of Santiago Ramón y Cajal can be considered to reflect the gradual development of Spanish science from the last third of the 19th century. Cajal promoted a national movement that had important consequences for Spanish science, mainly triggered by the creation of the “Junta para Ampliación de Estudios e Investigaciones Científicas,” an instrument he established to enrich scientific research and that was later to bear such abundant fruit. The school generated by Cajal profited from this development, through which all Cajal’s disciples received fellowships to train in laboratories across Europe. Unfortunately, the Spanish Civil War disrupted this revitalization of Spanish science and provoked the diaspora of many Spanish scientists. However, a political impulse, mostly following this spirit, was resumed in Spain during the eighties that successfully led to a renaissance in Spanish science.The work in the authors’ laboratories is supported by grants (to Juan Lerma) from the Spanish MICINN (BFU2011-24084), CONSOLIDER (CSD2007-00023), Prometeo/2011/086, and BFU2010-21377 (to Juan A. de Carlos).Peer reviewedPeer Reviewe

Analysis of photovoltaic plants with battery energy storage systems (PV-BESS) for monthly constant power operation

Photovoltaic generation is one of the key technologies in the production of electricity from renewable sources. However, the intermittent nature of solar radiation poses a challenge to effectively integrate this renewable resource into the electrical power system. The price reduction of battery storage systems in the coming years presents an opportunity for their practical combination with utility-scale photovoltaic plants. The integration of properly sized photovoltaic and battery energy storage systems (PV-BESS) for the delivery of constant power not only guarantees high energy availability, but also enables a possible increase in the number of PV installations and the PV penetration. A massive data analysis with long-term simulations is carried out and indicators of energy unavailability of the combined system are identified to assess the reliability of power production. The proposed indicators allow to determine the appropriate sizing of the battery energy storage system for a utility-scale photovoltaic plant in a planning stage, as well as suggest the recommended operating points made for each month through a set of graphs and indicators. The presence of an inflection zone has been observed, beyond which any increase in storage does not generate significant reductions in the unavailability of energy. This critical zone is considered the sweet spot for the size of the storage, beyond which it is not sensible to increase its size. Identifying the critical point is crucial to determining the optimal storage size. The system is capable of providing reliable supply of constant power in monthly periods while ensuring capacity credit levels above 95%, which increases the penetration of this renewable resource. Despite the fact that the study focuses exclusively on the analysis from an energy perspective, it is important to consider the constraints associated to real storage systems and limit their oversizing

Impact of the chemical preparation of the electrical n-contact on the performance of perovskite solar cells

Motivation: Solar energy is an alternative, sustainable energy source for mankind. Finding a convenient way to convert sunlight energy into chemical energy is a key step towards realizing large-scale solar energy utilization like artificial photosynthesis. A previous stage would be the complete study of a material with a high absorption capacity of sunlight and in this context, the perovskite type solar cells are presented. Perovskite solar cells are one of the most promising photovoltaic low-cost technologies due to the fast increase in efficiency from 3% in 2009 to 22% in 2016. In this work it has been studied how the combination of the main dopants in the n-contact of the solar cell, impacts on the optoelectronic properties of the device.Methods: Perovskite solar cell reference devices: a titanium dioxide (TiO2) compact layer was deposited onto FTO-coated glass by spray pyrolysis and performing as electron transporter material. A mesoporous TiO2 layer was deposited by spin coating using a particle paste and then sintered. The perovskite was made using one-step deposition method. A solution of Spiro-OMeTad as Hole Transporter Material was prepared and spun-coated. Finally, an 80 nm layer of gold was thermally evaporated on the top of the cell as cathode under high vacuum. The mesoporous layer was doped with lithium and TiCl4 respectively to study the electronic properties of the n-contact. The characterization of all the devices is carried out under a solar simulator, fluorescence and absorption analysis, electrochemical impedance spectroscopy and intensity modulated photocurrent spectroscopy to know the charge extraction.Results: Under environmental conditions and without a controlled atmosphere, reference cells were built with a 13% efficiency, quite close to the state-of-the devices currently fabricated in top research groups. It has been observed that doping the compact and mesoporous layers respectively with TiCl4, the best configuration from the electronic point of view is with the TiCl4 is deposited on the mesoporous layer. In the test with Lithium, a deleterious effect on all the properties of the cell is observed. Currently, some tests are being completed where Lithium and TiCl4 are combined, as the best configuration according to literature.Conclusions: The chemical and physical treatment of the n-contact in perovskite solar cells is crucial to ensure the best performance of the resulting photovoltaic device

UCO.MIPSIM: pipelined computer simulator for teaching purposes

Since pipelining is a very important implementation technique for processors, students in Computer Science need to achieve a good understanding of it. UCO.MIPSIM simulator has been developed to support teaching such concepts. This paper introduces the basics of pipelining and describes UCO.MIPSIM, its main components and its functions. The learning effectiveness of the simulator has been tested by means of the comparison with two learning tools, the traditional paper and pencil and another pipelined computer simulator. In this way, a tool evaluation methodology is also introduce