Passengers' perception of airlines' services: addressing systematic and random variation in tastes

This paper investigates heterogeneities in passengers' perceptions of airlines' services considering systematic and random variations in users' tastes. For this purpose, an efficient design of a stated preference survey is carried out, where attributes related to the in-flight travel and to the passenger`s experience before and after the flight are considered. A Random Parameter Multinomial Logit model is estimated with the obtained data, which also considers systematic variations in user tastes. The obtained results show that most of the parameters associated with the considered variables fit better to a normal or uniform distribution, and that part of their variance can be explained by interacting these variables with other variables such as gender, age, travel frequency or income level. The proposed model allows conclusions to be drawn and marketing policies to be implemented that directly aim at certain user segments, in addition to comprehensively explaining passenger behaviour by showing their preferencesThe work was supported in part by: Grant PLEC2021-007824 funded by MICIU/AEI/10.13039/501100011033 and, by the European Union NextGenerationEU/PRTR

An NMR study of hydrofluorocarbon mixed-gas solubility and self-diffusivity in the ionic liquid 1-ethyl-3-methylimidazolium dicyanamide

To date, the design of advanced separation processes, such as the extractive distillation with ionic liquids (ILs), for the separation of common close-boiling refrigerant blends relies almost exclusively on binary equilibrium data obtained for single-gas/solvent systems, thus neglecting the influence of possible mixture effects. In this work, Nuclear Magnetic Resonance (NMR) spectroscopy and pulsed gradient spin echo (PGSE) NMR are pro posed for the sequential assessment of the single and mixed-gas vapor-liquid equilibrium and self-diffusivity of two fluorinated refrigerants, difluoromethane (R-32) and pentafluoroethane (R-125), in the IL 1-ethyl-3-methy imidazolium dicyanamide at 303.1 K and pressures up to 4 bar, either as pure R-32 or using the commercial refrigerant blend R-410A. The results confirmed that the mixed-gas solubility and self-diffusivities were essen tially equal to those obtained with pure feed gas, thus significant mixing effects were not observed for this particular system. However, an increase in the self-diffusion coefficients was observed with the concentration of absorbed gas, which was more significant for the smallest hydrofluorocarbon (R-32) than for R-125. This technique also allowed evaluating the mobility of the IL moieties, which was slightly higher for the IL anion. Moreover, the self-diffusion coefficients of the IL ions also increased with the amount of gas absorbed, yet less markedly than for the refrigerants. Overall, the NMR technique proved to be an accurate method for the rapid screening of possible mixture effects in equilibrium and transport properties of refrigerant and IL systems, thus providing essential information for designing novel advanced separation processes.The authors acknowledge the financial support of MICIU/AEI/10.13039/501100011033 and the European Union NextGenerationEU/PRTR to projects TED2021-129844B-I00 and PID2022-138028OB-I00 (Universidad de Cantabria), and project PID2019-108552GB-I00 (ICTP-CSIC) as well as project LIFE4F-Gases (LIFE20CCM/ES/001748) co-funded by the European Union LIFE programme. F. Pardo thanks the postdoctoral fellowship IJC2020–043134-I “Juan de la Cierva Incorporación”. M. Viar acknowledges the FPU grant (FPU22/04137) awarded by the Spanish Ministry of Education and Professional Training

Low nickel loading carbon microfibers fabricated by electrospinning for the glycerol electrooxidation coupled with the continuous gas-phase CO2 reduction reaction towards formate

The glycerol market is currently experiencing a surplus due to increased biodiesel production,mcreating a demand for innovative approaches for its optimal utilization. Electrochemical valorization, particularly electro-oxidation, emerges as a promising solution for transforming excess glycerol into valuable products. Here, we report the use of carbon microfibers with ultralow nickel content (<5 wt %) to catalyze glycerol oxidation reaction (GOR), coupled with continuous gas-phase CO2 electroreduction to obtain formate. The humidified CO2-fed membrane electrode assembly electrolyzer, devoid of noble metals, efficiently produces oxidized products like lactate at concentrations of 0.144 g L-1 from glycerol and formate solutions reaching up to 100 g L-1 from CO2, surpassing previous methods employing commercial Pt-based materials. This novel approach not only enhances glycerol conversion efficiency but also contributes to sustainable carbon utilization, leading to the production of value added products.The authors gratefully acknowledge financial support through projects PID2019-108136RB-C31 (MCIN/AEI/10.13039/501100011033), PID2022-138491OB-C31 (MICIU/AEI/10.13039/501100011033 and ERDF/EU), TED2021–129810B-C21 (MCIN/AEI/10.13039/501100011033 and European Union Next Generation EU/PRTR), PLEC2022-009398 (MCIN/AEI/10.13039/501100011033 and European Union Next Generation EU/PRTR), PCI2024-155027-2 (MICIU/AEI/10.13039/501100011033/UE) and the “Complementary Plan in the area of Energy and Renewable Hydrogen” funded by Autonomous Community of Cantabria, Spain, and the European Union Next Generation EU/PRTR. The present work is related to CAPTUS Project. This project has received funding from the European Union's Horizon Europe research and innovation programme under grant agreement No 101118265. We are also grateful for the Bi carbon-supported nanoparticles prepared and provided by the group of Prof. V. Montiel and Dr. José Solla-Gullón from the Institute of Electrochemistry of the University of Alicante

Winter masquerades in Cantabria

El objetivo de esta propuesta de Trabajo de Fin de Máster consiste en realizar una aproximación a una tradición festiva de Cantabria. Se pretende analizar las denominadas mascaradas de invierno, una tradición que se remonta siglos atrás y que se desarrolla durante los primeros meses del año. Estas festividades tienen como protagonistas una serie de personajes que dan vida a rituales profanos vinculados a la fertilidad y la renovación. A lo largo de este trabajo, se va a hacer un repaso por estas mascaradas, sus características, su historia y evolución, así como su prolongado declive desde principios del siglo XX y a su posterior proceso de recuperación a partir de la década de los años ochenta de ese mismo siglo. También se expondrán estudios concretos de caso, como es el de la mascarada de Silió, más conocida como La Vijanera, y el de la mascarada de Polaciones. Para realizar este Trabajo de Fin de Máster, se empleará bibliografía específica, con el fin de mostrar las características más importantes de estas mascaradas y su evolución.The objective of this TFM proposal is to approach a festive tradition in Cantabria. The purpose is to analyse the so-called winter masquerades, a tradition that dates back centuries and which takes place during the first months of the year. The protagonists of these festivities are a series of characters who give life to profane rituals linked to fertility and renewal. This paper will review these masquerades, their characteristics, history and evolution, as well as their prolonged decline since the beginning of the 20th century and their subsequent recovery process from the 1980s onwards. Particular case studies will also be presented, such as the Silió masquerade, better known as La Vijanera, and the Polaciones masquerade. Specific bibliography will be used in order to show the most important characteristics of these masquerades and their evolution.Máster en Patrimonio Histórico y Territoria

Development of Wi-Fi coverage maps for network analysis

Este Trabajo de Fin de Grado presenta el estudio de las tecnologías de localización mediante WIFI para el posicionamiento de interiores, cuyos métodos principales consisten en el estudio de la RSSI y la huella digital (fingerprinting). Para la elaboración de este proyecto se ha desarrollado una aplicación destinada a detectar los identificadores BSSID de los puntos de acceso (APs) Wi-Fi cercanos, la aplicación permite capturar datos en tiempo real sobre la cobertura de los APs, facilitando la elaboración de planos de señal que visualizan la distribución de la conectividad WI-FI en interiores y el estudio de la intensidad de las señales de los APs en las distintas áreas de la universidad. El proyecto se divide en varias fases, comenzando por la selección de las tecnologías más adecuadas para la detección y visualización de datos. Utilizando métodos de WI-FI fingerprinting se recolectan los datos necesarios, que incluyen las potencias de señal de los APs y sus ubicaciones aproximadas. Estos datos servirán, una vez procesados, para la representación en planos que destacan las áreas con buena cobertura, identificando posibles puntos de mejora en la infraestructura de la red. Este trabajo no solo proporciona una herramienta para la gestión de las redes, sino que además plantea las bases para futuras mejoras y aplicaciones en el campo de la localización en los interiores de la universidad, así como la optimización de las redes inalámbricas en esta.This Final Degree Project presents the study of WIFI localization technologies for indoor positioning, whose main methods consist in the study of RSSI and fingerprinting. For the development of this project, an application has been developed to detect the BSSID identifiers of nearby Wi-Fi access points (APs), the application allows to capture real-time data on the coverage of the APs, facilitating the development of signal maps that visualize the distribution of WI-FI connectivity indoors and the study of the signal strength of the APs in different areas of the university. The project is divided into several phases, starting with the selection of the most suitable technologies for data detection and visualization. Using WI-FI fingerprinting methods, the necessary data is collected, including the signal strengths of the APs and their approximate locations. This data will be used, once processed, for the representation in maps that highlight the areas with good coverage, identifying possible points of improvement in the network infrastructure. This work not only provides a tool for network management, but also lays the groundwork for future improvements and applications in the field of indoor location in the university, as well as the optimization of wireless networks in the universityGrado en Ingeniería de Tecnologías de Telecomunicació

Green synthesis of cellulose acetate mixed matrix membranes: structure-function characterization

Although membrane technology is widely used in different gas separation applications, membrane manufacturers need to reduce the environmental impact during the membrane fabrication process within the framework of the circular economy by replacing toxic solvents, oil-based polymers, and such by more sustainable alternatives. These include environmentally friendly materials, such as biopolymers, green solvents, and surfactant free porous fillers. This work promotes the use of environmentally sustainable and low toxic alternatives, introducing the novel application of cellulose acetate (CA) as a biopolymer in combination with dimethyl carbonate (DMC) as a greener solvent and different inorganic fillers (Zeolite-A, ETS-10, AM-4 and ZIF-8) prepared without the use of toxic solvents or reactants. Hansen Solubility Parameters were used to confirm the polymer-solvent affinity. Pure CA and mixed matrix membranes were characterized regarding their hydrophilicity by water uptake and contact angle measurements, thermal stability by TGA, mechanical resistance, ATR-FTIR and scanning electron microscopy before evaluating the gas separation performance by single gas permeability of N2, CH4, and CO2. Conditioning of the CA membranes is observed causing reduction of the CO2 permeability values from 12,600 Barrer for the fresh 0.5 wt % ETS-10/CA membrane to 740 Barrer for the 0.5 wt % ZIF-8/CA membranes, corresponding to 24% and 4.2% reductions in CO2/CH4 selectivity and 30% and 24% increase in CO2/N2 selectivity for the same membranes. The structure-relationship was evaluated by phenomenological models which are useful at low filler loading considering flux direction and particle shape and size but still fail to explain the interactions between the DMC green solvent and CA matrix and fillers that are influencing gas transport performance different than other CA membranes.Financial support from the Spanish State Research Agency is gratefully acknowledged for the project grant PID2019-108136RB-C31/AEI/10.13039/501100011033 and the Early stage contract PRE2020-09765/aei/10.13039/5011100011033, and the Horizon Europe for the Bio4HUMAN GA101135144 project. A.T.C. also acknowledges the opportunity of performing a research stay at ITM

Targeted photodynamic therapy: gluconamide-modified cellulose nanocrystals as efficient photosensitizer delivery platforms against Gram-negative bacteria

Antimicrobial Photodynamic Therapy (aPDT) is an emerging strategy against resistant pathogenic bacteria, a serious global health threat. We describe herein the efficient preparation of photosensitized cellulose nanocrystals (CNC) using trialkoxysilane linkers for covalent incorporation of anionic (Rose Bengal: RB) and cationic (Toluidine blue O: TBO) photosensitizers (PSs), along with a N-alkyl-D-gluconamide ligand to specifically target Escherichia coli, as model nanosystems for aPDT. The synthesized nanomaterials exhibited high PS loading, high singlet oxygen quantum yield comparable to the solution, and good stability in aqueous media with minimal PS release under physiological conditions. Experimental viability tests in bacteria demonstrated their capability for aPDT, mitigating the inherent cytotoxicity of both PSs under dark conditions while retaining high phototoxicity against E. coli bacteria. The presence of gluconamide further enhanced photoactivity, highlighting the importance of surface functionalization with a specific bacterial ligand for improved efficacy. The CNC-supported RB system exhibited sufficient fluorescence for tracking via fluorescence microscopy, making it suitable for theranostics, integrating bioimaging and aPDT. Overall, photosensitized CNCs hold great promise as nanocarriers for combating topical infections caused by Gram-negative bacteria, addressing the urgent need for novel therapeutic strategies in infectious disease management while also mitigating antimicrobial resistance.This work was funded by MCIN/AEI/10.13039/501100011033 (projects PID2020-114347RB-C32 and PID2020-114347RB-C31, to VMM and JLC, respectively) and European Union NextGenerationEU/ PRTR (projects TED2021-129248B-I00 to MLF, and TED2021-132122BC22 to JLC and VMM), Gobierno Vasco-Eusko Jaurlaritza (project IT1639-22) to VMM, and Spanish Instituto de Salud Carlos III (projects PI22/00030) to MLF. RP-M, MT, and AA. thank MIU and NGEU for the postdoctoral contract (MARSA21/71), Investigo program funding (EU Next generation), and FPI fellowship (PRE2021-098894), respectively

Matrimid®/LaNi5 mixed matrix membranes for selective hydrogen separation from industrial waste gas streams

This study reports the synthesis, characterization, and evaluation of Matrimid®/LaNi5 mixed matrix membranes for selective hydrogen separation from industrial waste gas streams. Through a combination of experimental investigation and modelling, hydrogen absorption in LaNi5 intermetallic compounds and its impact on separation performance were explored. It was observed that the composite membranes exhibit significant enhancement in hydrogen permeation compared to pristine Matrimid® membranes. The results showed that Matrimid®/LaNi5 membranes deliver 5 times higher H2 permeability (107 Barrer) and higher selectivity (H2/CO2: 14.5, H2/N2: 83.5, H2/CH4: 78.5 and H2/CO: 84.5). Furthermore, hydrogen permeation flux modelling in Matrimid®/LaNi5 elucidated the contribution of each transport mechanism with high regression coefficients (>0.92) and within ±15 % error. Moreover, the results demonstrate the capability of Matrimid®/LaNi5 membranes to surpass Robeson upper bound for H2/CO2 while it is almost reached for H2/N2 and H2/CH4 separations, highlighting the potential of these new membranes for industrial-scale applications.This research is being supported by the Spanish Ministry of Science and Innovation through the projects PID2021-123120OB-I00, TED2021-129951B–C21, and “Complementary Plan for Energy and Renewable Hydrogen” additionally supported with funding from European Union NextGenerationEU (PRTR-C17.I1) and by Comunidad Autónoma de Cantabria. Furthermore, authors also acknowledge the funds received within the project PLEC2021-007718 financed by MCIN/AEI/10.13039/501100011033 and European Union Next GenerationEU/RTRP and the project PLAST4H2 EAPA 0018/2022 within the framework on the INTERREG ATLANTIC program. Gonzalo Moral is grateful to the FPU postgraduate research grant awarded by the Spanish Ministry of Science and Innovation

Efficient estimation of a partially linear panel data model with cross-sectional dependence

This paper considers efficiency improvements in a partially linear panel data model that accounts for possible nonlinear effects of common covariates and allows for cross-sectional dependence arising simultaneously from unobserved common factors and spatial dependence. A generalized least squares-type estimator is proposed by taking into account this dependence structure. Also, possible gains in terms of the rate of convergence are studied. A Monte Carlo study is carried out to investigate the proposed estimators finite sample performance. Further, an empirical application is conducted to assess the impact of the carbon price linked to the European Union Emission Trading System on carbon dioxide emissions

A hybrid trans-modal liquid crystal optical vortex generator

This work experimentally validates a large-aperture optical vortex generator using a novel hybrid structure, combining transmission electrode and modal techniques, in what we term the trans-modal technique. The continuous transmission electrode is designed to generate a linear voltage distribution between the contact electrodes, while the electrode stubs distribute the voltage across the active area. A high-resistivity layer of the conducting polymer PEDOT fills the gap between the electrodes, resulting in a completely continuous voltage distribution. A 1-cm aperture device is experimentally demonstrated, but the structure is completely scalable. Theoretical results validate the design, and experimental results demonstrate precise control over the topological charge for both positive and negative values of orbital angular momentum. Remarkably, the conversion efficiency for the first topological charges is almost 100%. The reduction in efficiency of the higher-order modes has been explained theoretically, and it is not caused by design but by the PEDOT characteristics. The fabrication process is straightforward, as the high-resistivity layer may also be inhomogeneous. This work contributes significantly to the field by introducing a novel method for optical vortex generation. The simplicity of the fabrication process, high conversion efficiency, and ability to control the topological charge make this technique a promising avenue for future research and applications.The authors would like to thank Prof. Ignacio Moreno for his helpful suggestions. J.F.A. acknowledges the support of the project RYC2022-035279-I funded by MCIN/AEI/10.13039/501100011033, Spain and FSE+. Also, by projects TED2021-130378B-C21 and PID2022-137269OB-C22 funded by MCIN/ AEI /10.13039/501100011033, Spain and by FEDER, Spain “A way to make Europe”. N. Bennis also acknowledges research project UGB 22-725 (Military University of Technology). D.C.Z. acknowledges the support of the project PRIN-2022 ALPHA (202288M84C) ”ALl-dielectric resonant metasurfaces enhancing PHoton emission phenomenA“ (CUP Master:D53D23001060006, CUP:B53D2300233 0006), Italian Ministry of University and Research (MUR), financed by the European Union, Next Generation EU. Finally, it has to be noted that this research was carried out on devices co-funded by the Warsaw University of Technology, Poland within the Excellence Initiative: Research University (IDUB) programme