Resultados de investigación

Synthesized H-ZSM-5 and H-Beta zeolites with hierarchical porosity (h-H-ZSM-5 and h-H-Beta) have been ion-exchanged with alkali (Na+ and K+) and alkaline-earth (Mg2+) metals and have been evaluated as catalysts to produce high value-added products through catalytic pyrolysis of lignin. In comparison with the thermal test, hierarchical zeolites in acid form are effective catalysts for lignin pyrolysis, favouring the production of valuable light compounds although reducing bio-oil* yield and increasing gas and coke formation. In this way, h-H-ZSM-5 zeolite promotes the formation of oxygenated aromatics, being guaiacols and syringols the major products. Alkali-exchanged variants of this zeolite enhance demethylation reactions improving the selectivity towards 2-methoxy-phenol and syringol, by modifying acid site properties. On the other hand, h-H-Beta zeolite, with larger pore size and stronger acidity, leads to higher concentration of oxygenated aromatics for both parent and ion-exchanged catalysts. Specifically, h-KH-Beta promotes the production of 2-methoxy-phenol and syringol. Besides, h-MgH-Beta stands out for its greater selectivity towards phenol and alkylphenols, such as dimethylphenol. Overall, the combination of accessibility, provided by the hierarchical porosity, with the different nature and strength of the acid sites, induced by the ion-exchange with alkali and alkaline-earth metals, allows tailoring the lignin catalytic pyrolysis process to selectively produce high value-added compounds.

This study explores the links between Big Five personality traits, academic passion—harmonious and obsessive—and academic engagement in Spanish university students. A sample of 518 undergraduates completed self-report measures of personality, academic passion, and engagement. Descriptive analyses, reliability tests, hierarchical regressions, and mediation models with bias‑corrected bootstrapping were conducted. Conscientiousness and neuroticism showed direct associations with engagement, while agreeableness displayed an indirect effect through harmonious passion. Harmonious passion emerged as the main mediator connecting personality traits to engagement, whereas obsessive passion showed weaker or negative associations. Overall, the results support the dualistic model of passion and emphasize the combined role of personality and autonomous motivation in shaping academic engagement. The findings offer guidance for designing interventions aimed at strengthening student well‑being and academic performance in higher education.

This study presents a novel approach to fabricating hydrogen-selective palladium membranes by continuous flowing electroless pore-plating, hereafter referred to as cf-ELP-PP. This procedure aims to significantly advance the manufacturing processes of dense membranes. In fact, the transition from traditional batch to continuous methods enhances production efficiency and membrane quality, thus being possible to reach improved hydrogen permeation capabilities. Particularly, these novel membranes exhibited a H2-permeance ranging between 3.29·10⁻⁴ and 4.77·10⁻⁴ mol m-2 s-1 Pa-0.5 with H₂/N₂ ideal separation factor greater than 10,000 for the entire set of experiments. This research also addresses key challenges related to the stability and efficiency of membranes, providing relevant insights for their operation during prolonged times even if unfavorable operating conditions are adopted. All these findings underscore the potential of cf-ELP-PP membranes for effective hydrogen purification in a wide variety of future industrial applications, aligning with the increasing demand for sustainable energy solutions. Moreover, the work also paves future enhancements in hydrogen production and separation processes by providing valuable insights for researchers in fields of materials science, chemical engineering, and renewable energy technologies

This database includes all the data from figures included in the publication: "Tailoring Pd-membranas prepared by continuous flowing electroless pore-plating:role of hydrazine concentration and solution Flow rate"

In this project, we construct an extended well-being variable in the US from 1999 to 2019, transforming household wealth into an income flow to approximate total consumption possibilities. Subsequently, we calculate the individual propensity to suffer well-being losses in the short term to assess economic insecurity. The dataset presents all variables necessary to construct the extended well-being variable, as well as the economic insecurity measure.

The production of green hydrogen is one of the main targets of current energy and environmental policies. In this context, thermochemical water splitting is one of the potential methodologies that enable its production. This process is based on the thermal reduction of a metal oxide, followed by its re-oxidation with water releasing hydrogen. The main problem of this process, which hinders its full-scale application, is that reducing the metal oxide usually requires very high temperatures (>1500 °C). To decrease this reduction temperature, nonstoichiometric oxides such as perovskites have been proposed. In a previous work, the authors have presented La1-xSrxMeO3±δ (x = 0.2–0.4; Me = Mn, Fe and Co) perovskites as active materials decreasing the operation temperature to 1400 °C. However, those perovskites showed a significant lack of stability upon cycling, limiting their use in a future scale-up of the process. In this work, we present a multi-substituted perovskite type A1-xA’xB1-yB’yO3±δ (La0.6Sr0.4Co0.2Fe0.8O3±δ, named LSCF) as redox material with increasing stability and remarkable activity in the hydrogen production cycles even at temperatures below 1000 °C. This material was synthesised by reactive grinding as a green synthesis method optimising the variables of the process. Three reduction temperatures for the thermochemical water splitting were evaluated in the range 800–1200 °C at the same oxidation temperature of 800 °C. LSCF perovskite has been used in powder form with a H2 production of 5.22 cm3STP/gmaterial⋅cycle when the reduction was performed at 800 °C and 6.83 cm3STP/gmaterial⋅cycle when this reduction step was performed at 1000 °C. Afterwards, the LSCF was shaped into two different macroporous structures looking for a potential scaling-up of the process: reticulated porous ceramic structure (RPC) and a ceramic monolith structure with straight and well-ordered channels in which the perovskite forms a thin layer over the internal channels surface. The macroscopic structures exhibited good activity and stability working isothermally at 800 °C under N2 atmosphere, reaching H2 productions higher than 10 cm3STP/gmaterial⋅cycle. Particularly, the monolithic structure, characterised by its open macroporosity improves the heat transfer phenomena and the contact between the gas-phase and the perovskite, obtaining a stable hydrogen production under isothermal conditions of 17 cm3STP/gmaterial⋅cycle at 800 °C. That could be increased up to 32.5 cm3STP/gmaterial⋅cycle when the reduction step of the thermochemical water splitting is performed at 1000 °C. To the best of our knowledge, this is the higher value obtained for hydrogen production by a perovskite in this application at this reaction conditions. These results confirm the LSCF as a potential material for green hydrogen production by low-temperature thermochemical cycles.

This dataset contains the data related to the article "Are Virtual Reality Serious Video Games More Effective Than Web Video Games?" with DOI 10.1109/MCG.2023.3244036. This dataset contains data of 289 computer science students divided into two groups: one composed of 110 students who played the game in VR format (hereinafter, VR group) and the other composed of 179 students who played it in Web format (hereinafter, Web group). The first tab of the file contains pre-test and post-test scores of the VR group and the second tab contains pre-test and post-test scores of the Web group, whereas the third tab of the file contains the results of a questionnaire fullfilled by the VR group and the fourth tab of the file contains the results of a questionnaire fullfilled by the Web group . All data was anonymized so that the identity of the participants cannot be ascertained. The aforementioned article can be accessed at https://doi.org/10.1109/MCG.2023.3244036.

The dataset contains the data of the two experiments of the article "Visual landmarks sharpen grid cell metric and confer context specificity to neurons of the medial entorhinal cortex", labeled "circular_platform" and "linear_track". There is an experiment directory for both. Within each experiment directory, there are several animal directories. Within each animal directory, there are several recording session directories. The data files are in the recording session directories. All included files are text files. The file names have the recording session name (e.g. jp693-11062015-0108) and an extension. A further text file in the database explains more details about the data, including a practical example on how to operate with them.

Rice husk (RH), a globally abundant agri-food waste, presents a promising renewable silicon source for producing SBA-15 mesoporous silica-based materials. This study aimed to synthesize and bifunctionalize SBA-15 using RH as a silica precursor, incorporating sulfonic and octadecyl groups to create a mixed-mode sorbent, RH-SBA-15-SO3H-C18, with reversed-phase and cation exchange properties. The material’s structure and properties were characterized using advanced techniques, including X-ray diffraction, infrared spectroscopy, N2 adsorption–desorption isotherms, nuclear magnetic resonance, and electron microscopy. These analyses confirmed an ordered mesoporous structure with a high specific surface area of 238 m2/g, pore volume of 0.45 cm3/g, pore diameter of 32 Å, and uniform pore distribution, highlighting its exceptional textural qualities. This sorbent was effectively utilized in solid-phase extraction to purify 29 alkaloids from three families—tropane, pyrrolizidine, and opium—followed by an analysis using ultra-high performance liquid chromatography coupled to ion-trap tandem mass spectrometry. The developed analytical method was validated and applied to gluten-free bread samples, revealing tropane and opium alkaloids, some at concentrations exceeding regulatory limits. These findings demonstrate that RH-derived RH-SBA-15-SO3H-C18 is a viable, efficient alternative to commercial sorbents for monitoring natural toxins in food, offering a sustainable solution for repurposing agri-food waste while addressing food safety challenges.

Clustering is a technique that allows data to be organized into groups of similar objects. DBSCAN (Density-Based Spatial Clustering of Applications with Noise) constitutes a popular clustering algorithm that relies on a density-based notion of cluster and is designed to discover clusters of arbitrary shape. The computational complexity of DBSCAN is dominated by the calculation of the ϵ-neighborhood for every object in the dataset. Thus, the efficiency of DBSCAN can be improved in two different ways: (1) by reducing the overall number of ϵ-neighborhood queries (also known as region queries), or (2) by reducing the complexity of the nearest neighbor search conducted for each region query. This paper deals with the first issue by considering the most relevant region query strategies for DBSCAN, all of them characterized by inspecting the neighborhoods of only a subset of the objects in the dataset. We comparatively evaluate these region query strategies (or DBSCAN variants) in terms of clustering effectiveness and efficiency; additionally, a novel region query strategy is introduced in this work. The results show that some DBSCAN variants are only slightly inferior to DBSCAN in terms of effectiveness, while greatly improving its efficiency. Among these variants, the novel one outperforms the rest.