Effect of preparation conditions on the polymorphism and transport properties of lanthanum molybdates

In this work, La6MoO12-based compounds were investigated as part of a new family of materials very competitive as hydrogen separation membranes [1,2]. La5.4MoO11.1 was synthesized by the freeze-drying precursor method and the calcination conditions were optimized in order to obtain single phases. Several cooling rates were applied and different polymorphs were obtained: a simple cubic fluorite symmetry (Fm-3m) for the sample cooled by quenching, and two different rhombohedral (R-3) space groups for the samples cooled at 50 ºC•min-1 and 0.5 ºC•min-1 (see Figure below). For the quenched sample, the Rietveld refinement was satisfactory in a Fm-3m space group. For the other two compositions no structural model was available and were indexed in a R-3 space group, however some small reflections were not given any intensity by the model used. Transmission electron microscopy confirmed the presence of superstructures for those samples. All ceramic materials were obtained with relative densities close to 100% after sintering at 1500 ºC. Stability studies demonstrated that all three polymorphs were stable in oxidizing and reducing conditions at 800 ºC for 48 hours. The three samples present a significant proton contribution to the conductivity at temperatures lower than 800 ºC. These results were confirmed by thermogravimetric analysis. The highest conductivity values were observed for the samples prepared by quenching. The three polymorphs display a small p-type electronic contribution to the overall conductivity in oxidizing conditions and n-type electronic one in very reducing conditions, much more significant for the samples cooled by quenching and at 50 ºC•min-1.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Analysis of double-parallel amplified recirculating optical-delay lines

A novel method of analysis of double-parallel amplified recirculating optical-delay lines (DPAROD) is presented. The location of the maxima and the minima of the transfer function for this configuration is calculated and experimentally demonstrated. The influence of different parameters, such as the coupling coefficients, gains, lengths of the fiber loops and fractional losses of the directional couplers, on the shape of the transfer function are analyzed. Different measurements have been taken to verify this model. The potential application of these interconnected delay loops as filters is a reason for developing this method.Publicad

Analysis and comparison of smart city initiatives

Complexity in cities is expected to become even higher in the short term, which implies the need to face new challenges. The Smart City (SC) model and its associate initiatives have become very popular for undertaking them but it is not often very clear what it really means. Starting with a previous classification of the initiatives developed under the SC model into two big categories, according to their approach to citizens, this paper aims to make a critical analysis of this model of city, and to propose the development of new initiatives for it based on Citizen-Centered Design methodologies. Living Labs, both as methodology and as organization, appear in this context as an interesting choice for developing initiatives with real citizen involvement along the entire design process, which it is expected to arise in later stages of research

Amplified Fiber-Optic Recirculating Delay Lines

Experimental and theoretical results on single- and double-amplified recirculating delay lines are presented. One of our aims is to emphasize their application as filters, showing a wide flexibility of design. Analysis of their performance in the spectral and time domains have been carried out. A novel method of understanding the behavior of double structures has been developed and successfully tested with experimental results employing Er-doped fiber amplifiers as delay lines.Publicad

Meteorización de las granulitas de Cabo Ortegal

[Resumen] Se realiza el estudio químico y mineralógico del proceso de alteración, en medios sustractivos, de las granuli tas de Cabo Ortegal, la precipi tación media anual supera los 1.300 mm. y las temperaturas medias mensuales extremas son 23ºC y 4,7ºC. Durante el proceso de meteorizaciór se origina una fuerte pérdida de Ca, Na y Mg y,en menor proporción, de Si con acumulación relativa de Fe y Al. Como productos de alteración aparecen filosilicatos 1:1 dioctaédricos, gibbsita, oxihidróxidos de hierro y micas y cloritas degradadas. La edafogénesis es de tipo fermonosialítico con una tendencia ferralítica, al menos en sus fases iniciales.[Abstract] This paper is a chemical and mineralogical study about the weathering process, in subtr&ctive environments, of the granul i tes in Cabo Ortegal. The mean annual precipitation is over 1.300 mm. and the mean monthly extreme temperatures are 23ºC and 4,7ºC . In the process of weathering there is an intense 10S8 of Ca, Na and Mg and, in a minar level , of Si, with a relative accumulation of Fe and Al. Proqucts of the weathering are 1: 1 dioctahedral phyllosilicates, gibbsi teiron oxyhydroxides and degraded micas and chlorites. The pedogenesis is of fermonosialli tic type wi th a ferrallitic tendence, in the first phases at least

Nueva escala de medición de mentalidad fija y aprendiente: desarrollo y validación

This paper describes the development of 33 scale items to assess people's fixed and growth mindset perceptions. The concept of fixed and growth mindset arises from the theory of Carol S. Dweck that has been discussed for years in various investigations in the school environment, however a scale of measurement in adults, particularly in workers for productivity, has not yet been developed. A measurement scale with three sections was designed with 70 items of fixed, learning mentality, taked the intelligence measurement of Buchanan, and Kern (2017), Dweck, Chiu, and Hong (1995), Dweck et al. (1999), as the reference. In the study, 97 supervisors from the maquiladora industry of Reynosa Tamaulipas participated; surveys were applied to three groups of participants to carry out the factorial reduction analysis process to verify the level of significance and validation of reagents. As a result, 15 fixed mindset were obtained. and 18 questions of growth mindset, which corroborate the referred theories of the measurement of the two dimensions of fixed and growth mindset. The use of this scale can serve as a reference for future research in adults to demonstrate their competence in productivity.Esta publicación describe el desarrollo de 33 reactivos de escala para evaluar las percepciones de mentalidad fija y aprendiente de las personas. El concepto de mentalidad fija y aprendiente surge de la teoría de Carol S. Dweck que ha sido discutida por años en diversas investigaciones en el ámbito escolar, sin embargo aún no se ha desarrollado una escala de medición en adultos particularmente en trabajadores para la productividad, se diseñó una escala de medición con tres secciones con 70 reactivos de mentalidad fija y aprendiente, tomando la referencia la medición de inteligencia de Dweck, Chiu y Hong (1995), Dweck et al. (1999) y Buchanan y Kern (2017). En el estudio participaron 97 supervisores de la industria maquiladora de Reynosa Tamaulipas, se aplicaron encuestas a tres grupos de participantes para realizar el proceso de análisis de reducción factorial para comprobar el nivel de significancia y validación de reactivos. Como resultado se obtuvieron 15 reactivos de mentalidad fija y 18 reactivos de mentalidad aprendiente, los cuales corroboran las teorías referidas de la medición de las dos dimensiones de mentalidad fija y aprendiente. El uso de esta escala puede servir como referente para futuras investigaciones en adultos para demostrar su competencia en la productividad

Dynamics of Scalar Field Dark Matter With a Cosh-like Potential

The dynamics of a cosmological model fueled by scalar field dark matter with a cosh-like potential plus a cosmological constant is investigated in detail. It is revealed that the late-time attractor is always the de Sitter solution, and that, depending on the values of the free parameters, the oscillating solution of the scalar field -- modeling cold dark matter -- mediates between some early stage (say, the radiation-dominated solution) and the accelerating de Sitter attractor.Comment: 9 pages, 17 figures, uses RevTe