Water management in hydrogen polymer exchange membrane fuel cells (PEMFC)

Current lifestyle makes energy to be essential beyond satisfying our basic needs. Nowadays, is not possible to talk about energy without dealing with its effect on the climate. The European Union (EU) consider that energy must be secure, competitive and sustainable and the energy union and climate is a European Commission’s priority. The EU’s Energy Union framework strategy was adopted back on February of 2015 and since then, the State of the Energy Union shows by its reports the progress made and the new targets and initiatives for the closest years. The Energy Union’s strategy is hold up by five key pillars mutually reinforcing which are: energy security, market integration, energy efficiency, decarbonisation of the economy and innovation. The EU’s Energy Union supports numerous cutting edge innovation projects where hydrogen is used. The main proposes related with hydrogen are for nuclear energy applications, energy storage and fuel cells. Hydrogen, which is the most abundant element in the universe, can be converted to electricity through electrochemical processes in a fuel cell in a single step and without any moving part. In addition, in a fuel cell the by-products are waste heat and water. For these reasons, fuel cells technology (specially PEMFCs technology) have the potential to be a element to take into account in energy production satisfying the global warming targets. However, PEMFCs need more research and development and an H2 large scale infrastructure. Nowadays, only the 4% of the hydrogen consumed is produced by electrolysis, the 96% left came from fossil fuels. The present bachelor thesis focuses in one of the main current challenges in fuel cell industry: water management. A correct water management is a key factor for high PEMFC performance and durability. In order to achieve a global vision of water management and also to set a zone of stable operation in the UC3M PEMFC laboratory for upcoming works this bachelor thesis is divided in 5 main chapters. The first chapter focuses in fuel cell technology from its origin to its nowadays main applications. The second chapter deals with the PEMFC and its state of art. In the third chapter a simplified modelling of balance of mass and water is performed for a theoretical analysis of the experimental conditions. The fourth chapter summarizes all the experiments performed in the UC3M PEMFC laboratory and gives as a result a zone of stable operation that will be useful for further projects. Finally, a global conclusion of the results obtained over the bachelor thesis is presented. This present bachelor thesis involves the starting point for future hydrogen PEMFC investigation in the UC3M.Ingeniería de la Energí

A Liouville type result for fractional Schrödinger operators in 1D

The aim of this master's thesis is to obtain an alternative and original proof of a Liouville type result for fractional Schrödinger operators in 1D without using a local extension problem, in the spirit of the recent work of Hamel et al. Thanks to this new proof we can extend the Liouville theorem to other nonlocal operators that do not have a local extension problem, being the first time that a result of this kind is proven. First, we introduce Schrödinger operators, the fractional Laplacian and its local extension problem. Then, we present a recent work about a nonlocal and nonlinear problem, where the prior study of fractional Schrödinger operators is needed. We also present the most important motivation for the study of Liouville type results: the conjecture of De Giorgi, and we review some Liouville type results both with local and nonlocal operators. Finally, we give the proof of the main theorems of the thesis

Detección de M señales gaussianas utilizando el desarrollo modificado de un proceso estocástico

Utilizando el desarrollo modificado de un proceso estocástico se propone una nueva metodología, alternativa a la basada en el desarrollo de Karhunen-Loeve, para el problema de detección de M señales Gaussianas en ruido Gaussiano blanco. Las soluciones proporcionadas no presentan el problema del cálculo de los autovalores y autofunciones asociados a la función de covarianza involucrada y son fácilmente implementables desde el punto de vista práctico

Proptech: A qualitative analysis of online real estate brokerage agencies in Spain

[EN] Purpose: The arrival of new companies that are more technological and scalable to the real estate sector has caused a revolution in a very conservative and not very innovative industry. The main objective of this research is to characterize the business model of proptech online brokerage companies in home sales in Spain, based on the traditional agency model. Design/methodology: Nine semi-structured interviews were conducted with the CEOs and managers of six proptech online real estate brokerage agencies in Spain. Their content was analyzed by means of the study and comparison of common patterns. Findings: During the digitalization process of the brokerage, a regression was detected back to more classic procedures typically found in traditional agencies, thus establishing an important difference as compared to other more transparent markets. Accordingly, a convergence occurs between the different real estate brokerage models (online and traditional), resulting in a hybrid model. Research limitations/implications: The limited number of agencies that operate in the online mode in Spain makes the sample size quite small. Practical implications: The results contribute greater transparency to a traditional sector characterized by its opacity, and they give visibility to the changes that are currently taking place, facilitating information to both professionals and users. Social implications: It contributes to the fulfillment of sustainable development goal number 9, concerning the promotion of development-oriented policies that support the creation of decent jobs, entrepreneurship, creativity and innovation. Originality/value: It expands the scientific literature dedicated to online real estate brokerage in Spain, given that as of today, we have no knowledge of any other published academic work on this topic. The research contributes to the vision that new sector agents have of it and those changes that are occurring within it.[ES] Objeto: La llegada de nuevas empresas más tecnológicas y escalables al sector inmobiliario ha provocado un movimiento disruptivo en una industria muy conservadora y poco innovadora. El objetivo principal de esta investigación es caracterizar el modelo de negocio de las empresas proptech online de intermediación en la compraventa de vivienda en España partiendo del modelo de la agencia tradicional. Diseño/metodología: Se realizaron nueve entrevistas semiestructuradas a los CEO y a personal con responsabilidad, pertenecientes a seis agencias proptech online de intermediación inmobiliaria en España. Su contenido se analizó mediante el estudio y comparación de patrones comunes. Aportaciones y resultados: En el proceso de digitalización de la intermediación se detecta una involución hacia procedimientos más clásicos propios de la agencia tradicional, estableciéndose una importante diferencia con otros mercados más transparentes. Se produce así una convergencia entre los distintos modelos de intermediación inmobiliaria (online y tradicional) dando lugar a un modelo híbrido. Limitaciones: El número limitado de agencias que operan en la modalidad online en España hace que el tamaño de la muestra sea reducido. Implicaciones prácticas: Los resultados aportan mayor transparencia a un sector tradicional caracterizado por su opacidad y visibilizan los cambios que están teniendo lugar en la actualidad, facilitando información tanto a los propios profesionales como a los usuarios. Implicaciones sociales: Contribuir al cumplimiento del objetivo de desarrollo sostenible número 9 sobre la promoción de políticas orientadas al desarrollo que apoyen la creación de puestos de trabajo decentes, el emprendimiento, la creatividad y la innovación. Valor añadido: Ampliar la literatura científica sobre la intermediación inmobiliaria online en España, puesto que a fecha de hoy no se conoce ningún trabajo académico publicado. El estudio aporta la visión que los nuevos agentes del sector tienen sobre el mismo y los cambios que en él se están produciendo. Palabras clave: agencia tradicional; estudio cualitativo; digitalización; intermediación inmobiliaria online; proptech Códigos JEL: M10, M19Asensio-Soto, JC.; Navarro Astor, E. (2022). Proptech: A qualitative analysis of online real estate brokerage agencies in Spain. Intangible Capital. 18(3):489-505. https://doi.org/10.3926/ic.209048950518

ADIPOSE TISSUE. METABOLIC ALTERATIONS AND EFFECT OF MICROBIOTA

Obesity is among the top health concerns across the globe, and it has been for many years, yet the world remains unable to stop it. Overweight and obesity follow a clear uptrend pattern and that will not change unless a real battle is waged against their main causes.The present review will explore the causes and mechanisms underlying this health crisis, focusing on what for many years has been disregarded: the active role that the adipose tissue plays in the development of the metabolic alterations regarding obesity and the undeniable implication of gut microbiota in supporting the existing mechanisms for weight gain and fat storage. The aim is to integrate most of the factors to provide a global vision of the processes happening obesity.The review has been methodically elaborated, bringing together information from many different experts in the different fields, striving for accurate and state-of-the-art information throughout the whole review, with special emphasis in the final fragment on the other major health crisis concerning the world right now: COVID-19.<br /

Antioxidant activity and lipid peroxidation in Artemia nauplii enriched with a DHA-rich oil emulsion and the effect of adding an external antioxidant based on hydroxytyrosol

Artemia nauplii catabolise polyunsaturated fatty acids (PUFA); in particular, they retroconvert docosahexaenoic acid (DHA, 22:6n-3), so enrichment is a continuous quest towards increasing PUFA through the use of PUFA-rich enrichment products. However, optimal conditions during enrichment (aeration, illumination and temperatures around 28 ºC) tend to accelerate autoxidation of PUFA, and the formation of potentially toxic oxidation products. Water-soluble antioxidants like the polyphenolic compound hydroxytyrosol (3,4-dihydroxyphenylethanol), a polar molecule found in the water fraction resulting after the milling process of olives, arise as promising compounds to prevent oxidation during Artemia enrichments. We investigated the antioxidant activity and lipid peroxidation in Artemia nauplii during enrichment, and the effect of adding an external antioxidant based on hydroxytyrosol during the enrichment with a PUFA-rich emulsion (M70). For this purpose, the activity of antioxidant enzymes (catalase, superoxide dismutase, glutathione-S-transferase, glutathione peroxidase), as well as lipid peroxidation, were determined in enriched and unenriched Artemia nauplii. To validate antioxidant activity and lipid peroxidation, in a first experiment, nauplii were enriched with microalgae (Tetraselmis suecica), yeast (Saccharomyces cerevisiae) and M70 emulsion. In a second experiment, enrichment with a commercial emulsion (DC Super Selco), M70, and a combination of M70 and hydroxytyrosol (Hytolive, HYT) added as an external antioxidant was performed. The combination of M70 with HYT produced the best results, in terms of activity of antioxidant enzymes. The analysis of the fatty acids from total lipids showed that the addition of hydroxytyrosol preserved the DHA percentage of enriched nauplii