Etendue-Matched Solar Tower Beam-Down System for High-Temperature Industrial Processes

The standard Concentrating Solar Thermal (CST) mono-tower technology, which uses one receiver placed on top of a tower to which all heliostats in the heliostat field aim to, is regarded as one of the best and most promising technologies for various CST-driven applications, namely CST power plants, solar metallurgical processes, thermochemical production of solar fuels and waste materials recycling. However, the technology has some technical challenges concerning optical performance/tolerances, system dimensions, operation and maintenance issues, etc. An alternative to this standard CST mono-tower technology is the so-called beam-down technology, where a special mirror is placed on the top of the tower, instead of a receiver, to redirect the incident radiation from the heliostat field onto a receiver/reactor placed closer to the ground and potentially delivering higher concentrations at the receiver than the standard CST mono-tower technology. This paper presents a new approach to improve the optics of beam-down systems, applies it to the optical design of a specific system, and shows the optical behavior of this design at two locations: Évora (Portugal) and Hurghada (Egypt). The approach uses etendue-matching between all the optical stages to minimize the optical losses between them. To analyze the optical behavior of the system designed, as an example, using the etendue-matching approach, raytracing simulations were carried out and are presented also in the paper.Projecto H2020 INSHIP - Grant No. 731287

Fe3O4-TiO2 Thin Films in Solar Photocatalytic Processes

The optical properties of 5wt% Fe3O4-TiO2 thin films were evaluated in detail with the aim of proposing a mechanism for solar photocatalytic processes and highlighting the advantages over the use of bare TiO2. The results showed that the incorporation of 5wt% Fe3O4 enhanced the optical properties by a redshift to a wavelength in the visible range, reducing the anatase/rutile band gap energy from 3.2 eV to 2.8 eV. Photoluminescence studies reveal a superior separation efficiency of photoexcited electron-hole pairs when Fe3O4 nanoparticles (NPs) are present in the photocatalyst. X-ray photoelectron spectroscopy spectra confirm the presence of Fe3O4 and existence of a chemical bonding between TiO2 and Fe3O4 NPs. Moreover, in this study, a mechanism of solar photocatalytic processes involving Fe3O4-TiO2 thin films is proposed and it is supported by experimental results. Finally, solar photocatalytic experiments were carried out, indicating that the effectiveness for the removal of the selected pharmaceutical is considerably improved when the composite material is used as catalyst. Furthermore, it was demonstrated that the photocatalytic activity of the prepared Fe3O4-TiO2 thin films depends on their thickness, achieving the highest pharmaceutical removal yields using the 2 mu m thick sample. The stability and reusability of the catalyst was confirmed studying the photocatalytic activity over three cycles

Spectroscopic Ellipsometry Study on Tuning the Electrical and Optical Properties of Zr-Doped ZnO Thin Films Grown by Atomic Layer Deposition

This work reports the ellipsometry analysis of atomic layer deposition (ALD) films of ZnO doped with Zr to determine parameters like free carrier concentration and mobility. Thin films of zinc oxide (ZnO) and Zr-doped ZnO of thickness similar to 100 nm were prepared by atomic layer deposition on sapphire, SiO2/Si(100), and Si(100) substrates. Variable-angle spectroscopic ellipsometry was used to study their optical properties in the 0.5-3.5 eV spectral range. The optical constants were accurately obtained using a model that combines Drude and Tauc-Lorentz oscillators with Bruggeman effective medium approximations, allowing the inclusion of a roughness layer in the optical model. The effect of Zr doping (ca. 1.9- 4.4 atom %) was then investigated in both as- prepared samples and samples annealed in the temperature range of 100-300 degrees C. All of the films exhibited good optical transparency (ca. 70-90% in the visible region). For doping levels below 2.7 atom %, the real part of the dielectric permittivity reveals a semiconductor-to-metal transition in the near-infrared (NIR) region, as the permittivity goes from positive to negative. Besides, the plasma energy increases with increasing Zr concentration, and both resistivity and carrier concentration exhibit slightly parabolic behaviors, with a minimum of similar to 1.5 x 10(-3) Omega cm and a maximum of 2.4 x 10(20) cm(-3), respectively, at the same critical Zr concentration (2.7 atom %). In contrast, the carrier mobility decreases rapidly from 76.0 to 19.2 cm(2)/(V s) with increasing Zr content, while conductivities and carrier mobilities worsen when the annealing temperature increases, probably due to the segregation of ZnO crystals. Finally, the optical band gap is very stable, revealing its interesting independence of substrate composition and annealing temperature, as it collapses to a single master curve when band gap energy is plotted versus free carrier concentration, following the Burstein-Moss effect. Overall, the Zr-doped ZnO films studied here would be a highly desirable system for developing thermally stable transparent conductive oxides (TCOs)

Nueva especie de diatomea (Bacillariophyceae) en una fuente termal en el archipiélago de Azores (Isla de San Miguel, Océano Atlántico)

[EN] Background: Due to their isolation, islands offer excellent areas for the study of distribution of benthic diatoms. On the other hand, diatoms bearing canal raphe have received less attention compared to other groups of diatoms such as Navicula, Pinnularia or Amphora. Questions: Is it possible that thermal springs on islands offer a refuge for infrequent diatom species? Studied species: Platichthys furnensis C. Delgado, V. Gonçalves & S.F.P. Almeida sp. nov. Study site and dates: The species here described was collected in the epilithon of a thermal spring in São Miguel Island (Azores Archipelago, Portugal) in September 2015. Methods: This new taxon was compared to other diatom species of the genera Nitzschia, Tryblionella, Entomoneis and Hantzschia and to the other species of the genus Platichthys. The morphology is documented by light and scanning electron images and discussed in detail. Results: Platichthys furnensis was found in a thermal pool, a similar habitat to the one where P. krammeri type was collected in Chile in 1940. P. furnensis has many structures that are characteristic of the recently described genus Platichthys, including raised canal raphe and fibulae, compressed valve face, steep valve face and numerous open copulae. Conclusions: The description of the new taxon is interesting because it is the first species within Platichthys to be described from the Northern Hemisphere[ES] Antecedentes: Debido a su aislamiento, las islas son zonas excelentes para el estudio de la distribución de diatomeas bentónicas. Por otro lado, las diatomeas con canal rafiano han sido menos estudiadas que otros grupos como Navicula, Pinularia o Amphora. ¿Es posible que fuentes termales en islas ofrezcan un refugio para especies de diatomeas poco frecuentes? Platichthys furnensis C. Delgado, V. Gonçalves & S.F.P. Almeida La especie aquí descrita fue recogida en el epiliton de una fuente termal en la isla de São Miguel (Azores Archipielago, Portugal) en Septiembre de 2015. Este nuevo taxón se comparó con las características generales de los géneros Nitzschia, Tryblionella, Entomoneis y Hantzschia y con otras especies del género Platichthys. Su morfología se documenta mediante imágenes de microscopio óptico y electrónico discutiéndose en detalle. Platichthys furnensis se encontró en una fuente termal, un hábitat similar a donde fue recogida el tipo de P. krammeri en 1940 en Chile. P. furnensis tiene características del género Platichthys incluido el canal rafiano elevado, fibulas robustas, la cara valvar comprimida y numerosas cópulas abiertas. La descripción de nuevos taxones es interesante porque es la primera especie dentro de Platichthys que se describe en el hemisferio norte. algas de agua dulce, aguas termales, diatomeas, epiliton, isla volcánica, PlatichthysSIPart of the work was funded by FEDER funds through the Operational Programme for Competitiveness Factors - COMPETE and by National Funds through FCT - Foundation for Science and Technology under the UID/BIA/50027/2013 and POCI-01-0145-FEDER-006821. We also thank the Department of Biology and the Foundation of Science and Technology, Portugal for the strategic project granted to Geobiotec (UID/GEO/ 04035/2019

Engineering the HOMO–LUMO gap of indeno[1,2- b]fluorene

A direct, efficient and versatile strategy for the modulation of optoelectronic and magnetic properties of indeno[1,2-b]fluorene has been developed. 4-Substituted-2,6-dimethylphenyl acetylene groups placed in the apical carbon of the five-membered rings lead to redshifted absorption maxima (lmax ranging from 600–700 nm) and considerable narrowing of the HOMO–LUMO energy gap (down to 1.5 eV). Experimental and theoretical data show an increase in the diradical character (y) and a decrease of the singlet-triplet energy gap. Moreover, we have investigated the single-molecule conductance of the antiaromatic indeno[1,2-b]fluorene for the first time by including thiomethyl (-SMe) anchor groups on the phenylacetylene moiety. Conductance values one order of magnitude higher than those of a reference linear 3-ring para-phenylene ethylene have been found, despite the longer length of the S-to- S molecular junction. First principles transport calculations support this high conductance value.MCIN/AEIERDF A way of making Europe PGC2018-101873-A-I00 FEDER/Junta de Andalucia-Consejeria de Economia y Conocimiento A-FQM-221-UGR18Instituto de Salud Carlos IIISpanish GovernmentEuropean Commission PID2019-106732GB-I00 PID2019-105458RB-I00 PRE2018-083406'Severo Ochoa' Programme for Centers of Excellence in RD SEV-2016-0686'Maria de Maeztu' Programme for Units of Excellence in RD CEX2018- 000805-MMinisterio de Universidades FPU19/03751 MCIN/AEI PTA2017-13681-IComunidad de Madrid 2019-T1/IND-16384European Social Fund (ESF

Tungsten-titanium mixed oxide bronzes: Synthesis, characterization and catalytic behavior in methanol transformation

[EN] Tungsten oxide bronze-based materials show extremely adaptive structural and compositional features that make them suitable for functional properties modulation. Herein we report the preparation of a series of Ti-containing tungsten oxide catalysts presenting a hexagonal tungsten bronze-type structure. The insertion of Ti4+ within the structure (likely in the octahedral framework of the hexagonal tungsten bronze) leads to an increase in the number of strong acid sites, and the disappearance of W5+ surface species found in the undoped tungsten oxide. With the aim of studying the acid-redox properties of the titled catalysts, the catalytic transformation of methanol has been carried out in the presence and the absence of O-2 in the feed. Both catalytic activity and the acid-redox properties of these catalysts are highly dependent on catalyst composition and reaction conditions applied (i.e. in the presence or in the absence O-2 in the feed). Aerobic experiments show the depletion of the redox functionality (i.e. no formaldehyde detected in the products) when Ti4+ is incorporated in the framework (i.e. 100% selectivity to dimethyl ether). On the other hand, all the catalysts show the loss of the redox function and a decrease in the catalytic activity when anaerobic conditions are used. In the absence of oxygen, the catalysts are still active in the dehydration of methanol to dimethyl ether, i.e. they maintain their acid functionality even when oxygen is not present in the feed. The results are discussed in terms of the available surface active sites present in each case.Authors would like to thank DGICYT in Spain for RTI2018-099668-B-C21, CTQ2015-68951-C3-1-R and MAT2017-84118-C2-1-R projects. Authors from ITQ also thank Project SEV-2016-0683 for supporting this research. D.D. thanks MINECO and Severo Ochoa Excellence Program for his fellowship (SVP-2014-068669). Finally, authors thank the Electron Microscopy Service of SCSIE of Universitat de Valencia for their support.Delgado-Muñoz, D.; Soriano Rodríguez, MD.; Solsona Espriu, BE.; Zamora Blanco, S.; Agouram, S.; Concepción Heydorn, P.; López Nieto, JM. (2019). Tungsten-titanium mixed oxide bronzes: Synthesis, characterization and catalytic behavior in methanol transformation. Applied Catalysis A General. 582:1-10. https://doi.org/10.1016/j.apcata.2019.05.026S11058

Auge y colapso de la demanda de viviendas en España : factores determinantes

En este artículo se presenta un modelo de demanda de viviendas que permite analizar las causas que motivaron el boom inmobiliario protagonizado por la economía española, así como su posterior colapso. Según nuestro modelo, el boom tuvo su origen en el alza especulativa de precios, que produjo un doble efecto. Por un lado, el aumento de la riqueza inmobiliaria incrementó la capacidad financiera familiar, induciendo una mayor propensión al endeudamiento y a la inversión residencial. Por otro, el hecho de que la revalorización de la vivienda superara por momentos la cuota hipotecaria indujo un incremento adicional de la demanda de aquéllas. Sin embargo, estas fuerzas comenzaron a jugar en sentido contrario tras la explosión de la burbuja, provocando un brusco desplome de las compraventas. El modelo pone de relieve que la secular preferencia de los españoles por la vivienda en propiedad tenía un fundamento económico que ahora ha desaparecidoThis article presents a model for the demand for housing which allows one to analyze the determinants of the housing boom and bust experienced by the Spanish economy. According to this model, the boom was caused by a speculative increase in prices, which yielded two effects: on the one hand, the rise in wealth associated with the value of real estate increased households’ financial capacity, leading to a higher propensity to engage in debt and to invest in real estate. On the other hand, the fact that the appreciation in the value of housing was larger at certain times than the value of the mortgage to be paid, led to an even larger increase in the demand for housing. However, these forces began to act in the opposite direction after the bust of the housing bubble, causing an abrupt reduction in the demand for real estate. The model shows that the long term preference of Spaniards for house ownership rested on economic foundations which have now disappeare

Auge y colapso de la demanda de viviendas en España : factores determinantes

En este artículo se presenta un modelo de demanda de viviendas que permite analizar las causas que motivaron el boom inmobiliario protagonizado por la economía española, así como su posterior colapso. Según nuestro modelo, el boom tuvo su origen en el alza especulativa de precios, que produjo un doble efecto. Por un lado, el aumento de la riqueza inmobiliaria incrementó la capacidad financiera familiar, induciendo una mayor propensión al endeudamiento y a la inversión residencial. Por otro, el hecho de que la revalorización de la vivienda superara por momentos la cuota hipotecaria indujo un incremento adicional de la demanda de aquéllas. Sin embargo, estas fuerzas comenzaron a jugar en sentido contrario tras la explosión de la burbuja, provocando un brusco desplome de las compraventas. El modelo pone de relieve que la secular preferencia de los españoles por la vivienda en propiedad tenía un fundamento económico que ahora ha desaparecidoThis article presents a model for the demand for housing which allows one to analyze the determinants of the housing boom and bust experienced by the Spanish economy. According to this model, the boom was caused by a speculative increase in prices, which yielded two effects: on the one hand, the rise in wealth associated with the value of real estate increased households’ financial capacity, leading to a higher propensity to engage in debt and to invest in real estate. On the other hand, the fact that the appreciation in the value of housing was larger at certain times than the value of the mortgage to be paid, led to an even larger increase in the demand for housing. However, these forces began to act in the opposite direction after the bust of the housing bubble, causing an abrupt reduction in the demand for real estate. The model shows that the long term preference of Spaniards for house ownership rested on economic foundations which have now disappeare

La influencia de la riqueza financiera sobre el consumo privado : análisis de la experiencia española durante la “Gran Recesión”

En línea con la teoría dominante del consumo agregado, los estudios llevados a cabo en España sobre el comportamiento del consumo privado han confirmado el papel determinante de la renta real disponible y la riqueza real en la explicación de la evolución de este componente fundamental de la demanda global. Sin embargo, un análisis de las fluctuaciones que ha registrado el consumo privado en nuestro país durante la llamada Gran Recesión, si bien ratifica la relevancia explicativa de las variables señaladas, pone también de relieve que la riqueza total no parece el complemento idóneo para explicar las fluctuaciones recientes de esta variable. En contraste con los resultados de los últimos modelos del Banco de España, y en consonancia con los obtenidos por otros autores, nuestro análisis confirma, en efecto, que, junto con la renta real disponible, la evolución de la riqueza financiera resulta decisiva para explicar la evolución del consumo privado en España durante la última crisis, lo cual revaloriza el papel de las teorías que otorgan a las magnitudes financieras una influencia determinante en la generación de las fluctuaciones económicas. Esta conclusión es relevante para la política económica española, ya que la mejora que está experimentando la riqueza financiera en España, como consecuencia entre otras cosas de la reducción de la prima de riesgo, abre una válvula de escape, adicional a la de las exportaciones, en el círculo vicioso conformado por la secuencia “bajo consumo - bajo empleo – baja renta disponible – bajo consumo” que según el diagnóstico tradicional estaría cercenando cualquier posibilidad de recuperación autónoma por parte de nuestra economíaIn line with the main core of the theory of aggregate consumption, different studies undertaken in Spain confirm the leading role of real disposable income and real wealth in explaining the evolution of this important component of aggregate demand. However, an in-depth analysis of the fluctuations experienced by private consumption during the Great Recession shows that, while these variables are indeed very relevant when trying to explain the evolution of such consumption, it also shows that total wealth is not the most adequate complement to explain the most recent fluctuations of this variable. In contrast with the results of the latest models of the Bank of Spain and in line with what has been suggested by other authors, our analysis confirms that the evolution of financial wealth is, together with real disposable income, a decisive variable for explaining the evolution of private consumption during Spain’s last long crisis. This finding lends credit to the theories which attribute to financial variables a determining influence on the generation of economic cycles. This conclusion is relevant for Spanish economic policy, since the great expansion that financial wealth is experiencing as a results, among other things, from the reduction of the risk spread, opens a safety valve, along with exports, within the vicious cycle formed by the sequence “low consumption-low employment-low disposable income-low consumption” which, according to traditional diagnoses, would hinder any possibility for the autonomous recovery of our econom

Prediction of Anti-Glioblastoma Drug-Decorated Nanoparticle Delivery Systems Using Molecular Descriptors and Machine Learning

The theoretical prediction of drug-decorated nanoparticles (DDNPs) has become a very important task in medical applications. For the current paper, Perturbation Theory Machine Learning (PTML) models were built to predict the probability of different pairs of drugs and nanoparticles creating DDNP complexes with anti-glioblastoma activity. PTML models use the perturbations of molecular descriptors of drugs and nanoparticles as inputs in experimental conditions. The raw dataset was obtained by mixing the nanoparticle experimental data with drug assays from the ChEMBL database. Ten types of machine learning methods have been tested. Only 41 features have been selected for 855,129 drug-nanoparticle complexes. The best model was obtained with the Bagging classifier, an ensemble meta-estimator based on 20 decision trees, with an area under the receiver operating characteristic curve (AUROC) of 0.96, and an accuracy of 87% (test subset). This model could be useful for the virtual screening of nanoparticle-drug complexes in glioblastoma. All the calculations can be reproduced with the datasets and python scripts, which are freely available as a GitHub repository from authors. View Full-TextThe APC was funded by IKERDATA, S.L. under grant 3/12/DP/2021/00102—Area 1: Development of innovative business projects, from Provincial Council of Vizcaya (BEAZ for the Creation of Innovative Business Innovative business ventures)