Scientific Papers in SCI

Abstract

The effects of a remote oxygen plasma (ROP) treatment on the surface of commercial graphite felts were investigated and compared against a conventional thermal treatment. In contrast to methodologies where the sample is directly exposed to the plasma, ROP allows for a high control of sample-plasma interaction, thereby avoiding extensive etching processes on the fibre surface. To assess the impact of ROP treatment time, the electrodes were subjected to three different periods (10, 60, and 600 seconds). X-ray photoelectron spectroscopy showed that the ROP treatment introduced nearly three times more surface oxygen functionalities than the thermal treatment. Raman spectroscopy measurements revealed a significant increase in amorphous carbon domains for the ROP samples. The thermal treatment favoured increases in graphitic defects and resulted in an order of magnitude larger ECSA compared to the ROP treated materials despite having lower content in oxygen functionalities. The electrochemical analysis showed enhanced charge-transfer overpotentials for GF400. The ROP samples exhibited a lower mass-transport overpotential than the thermally treated material and had similar permeabilities, which overall translated to the thermal treatment offering better performance at fast flow rates. However, at slow flow rates (similar to 10 mL min-1), the ROP treatment for the shortest period offered comparable performance to conventional thermal treatment.

Remote oxygen plasma is compared to conventional thermal activation of electrodes for flow batteries and their impact on the mass transport and charge transfer properties of the resulting carbons.

Abstract

In recent years, the implementation of CO2 capture systems has increased. To reduce the costs and the footprint of the processes, different industrial wastes are successfully proposed for CO2 capture, such as gypsum from desulfurization units. This gypsum undergoes an aqueous carbonation process for CO2 capture, producing an added-value solid material that can be valorized. In this work, panels have been manufactured with a replacement of (5 and 20%) commercial gypsum and all the compositions kept the water/solid ratio constant (0.45). The density, surface hardness, resistance to compression, bending, and fire resistance of 2 cm thick panels have been determined. The addition of the waste after the CO2 capture diminishes the density and mechanical strength. However, it fulfills the requirements of the different European regulations and diminishes 56% of the thermal conductivity when 20%wt of waste is used. Although the CO2 waste is decomposed endothermically at 650 degrees C, the fire resistance decreases by 18% when 20%wt. is added, which allows us to establish that these wastes can be used in fire-resistant panels. An environmental life cycle assessment was conducted by analyzing a recycling case in Spain. The results indicate that the material with CO2 capture waste offers no environmental advantage over gypsum unless the production plant is located within 200 km of the waste source, with transportation being the key factor.

Abstract

Replacing homogeneous catalytic processes by heterogeneous routes based on the utilization of solid catalysts is of great interest from an environmental point of view. Owing to their genuine pore structure, zeolites such as mordenites (MOR) have emerged as game-changing materials to enable the heterogenization of catalytic processes including methanol carbonylation. Cu-exchange zeolites take the edge over pristine zeolites, leading to enhanced catalytic performance in terms of greater activity, selectivity, and stability. Herein, the overall catalytic activity and stability can be modulated upon controlling the environment and location of copper active sites in zeolites. In this study, Cu-exchanged mordenites were strategically synthesized to investigate the role of Cu location inside of MOR cavities under working conditions by means of in situ/operando infrared (IR) spectroscopic studies. The results obtained revealed that a major proportion of Cu in the MR-8 cavities notably enhances the activity and stability of the catalyst. This study provides crucial insights for fine-tuning zeolite catalysts to achieve the heterogenization of homogeneous carbonylation processes.

Abstract

The plant cuticle is located at the interface of the plant with the environment, thus acting as a protective barrier against biotic and abiotic external stress factors, and regulating water loss. Additionally, it modulates mechanical stresses derived from internal tissues and also from the environment. Recent advances in the understanding of the hydric, mechanical, thermal, and, to a lower extent, optical and electric properties of the cuticle, as well as their phenomenological connections and relationships are reviewed. An equilibrium based on the interaction among the different biophysical properties is essential to ensure plant growth and development. The notable variability reported in cuticle geometry, surface topography, and microchemistry affects the analysis of some biophysical properties of the cuticle. This review aimed to provide an updated view of the plant cuticle, understood as a modification of the cell wall, in order to establish the state-of-the-art biophysics of the plant cuticle, and to serve as an inspiration for future research in the field.

Abstract

This study presents a novel approach for boosting the selectivity of 5-hydroxymethylfurfural (HMF) production from glucose through electrochemical modification of graphite materials. Three distinct graphitic substrates were subjected to controlled electrochemical treatments utilizing sodium sulfate or phosphoric acid as electrolytes. The process expanded the graphite particles/pieces and introduced oxygenated functional groups to the exposed surfaces while preserving the structural integrity of the bulk material. The resulting modifications influenced the type and quantity of Lewis and Brønsted acidic sites, providing exhaustive control over reaction pathways leading to HMF. This electrochemically modified graphite demonstrated superior tunability compared to traditional metal-based catalysts, enabling dynamic optimization of reaction conditions for enhanced HMF yield. The controlled introduction of functional groups facilitated the tailoring of active sites, significantly impacting the kinetics of glucose conversion and achieving HMF selectivity up to 95%. This level of precision in controlling catalytic properties is essential for maximizing HMF yield while minimizing undesired by-product formation, addressing a critical challenge in HMF production.

Abstract

The escalating concerns about traditional reliance on fossil fuels and environmental issues associated with their exploitation have spurred efforts to explore eco-friendly alternative processes. Since then, in an era where the imperative for renewable practices is paramount, the aromatic synthesis industry has embarked on a journey to diversify its feedstock portfolio, offering a transformative pathway toward carbon neutrality stewardship. This Review delves into the dynamic landscape of aromatic synthesis, elucidating the pivotal role of renewable resources through syngas/CO2 utilization in reshaping the industry's net-zero carbon narrative. Through a meticulous examination of recent advancements, the current Review navigates the trajectory toward admissible aromatics production, highlighting the emergence of Fischer-Tropsch tandem catalysis as a game-changing approach. Scrutinizing the meliorated interplay of Fe-based catalysts and HZSM-5 molecular sieves would uncover the revolutionary potential of rationale design and optimization of integrated catalytic systems in driving the conversion of syngas/CO2 into aromatic hydrocarbons (especially BTX). In essence, the current Review would illuminate the path toward cutting-edge research through in-depth analysis of the transformative power of tandem catalysis and its capacity to propel carbon neutrality goals by unraveling the complexities of renewable aromatic synthesis and paving the way for a carbon-neutral and resilient tomorrow.

Abstract

We report the development of a multimodal lanthanide vanadate system suitable as dual T₁-T₂ MRI contrast agent as well as a luminescent imaging probe in the near-infrared region, using Dy³⁺ and Gd³⁺ as T₂ and T₁ components, respectively, and Nd³⁺ as the luminescent center. The vanadate matrix was chosen to avoid the undesired solubility associated to previously reported fluoride-based contrast agents. With such aim, we first optimized the design of the MRI system by comparatively evaluating the magnetic relaxivities of two different architectures consisting of i) uniform NPs incorporating both paramagnetic cations in solid solution (single-phase NPs), and ii) core-shell NPs consisting of a DyVO₄ core coated with a homogeneous GdVO₄ shell (DyVO₄@GdVO₄). We found that, although both samples presented magnetic relaxivity properties that make them adequate for their use as dual T₁-T₂ contrast agents for magnetic resonance imaging, the core-shell architecture would be more suitable because of their higher magnetic relaxivity values. Secondly, to prepare the multimodal system, the GdVO₄ layer of such optimal dual T₁-T₂ MRI probe was doped with Nd³⁺ cations. An inert YVO₄ intermediate shell was also introduced between the cores and the outer layer aiming to avoid energy transfer from Nd³⁺ to Dy³⁺, which would cause luminescence quenching. These core-shell-shell nanoparticles showed magnetic relaxivity values similar to those of the core-shell system and an intense luminescence in the near-infrared region. Moreover, they were dispersible and chemically stable under conditions that mimic the physiological media, and they were nontoxic for cells. Therefore, such multimodal nanoparticles meet the main requirements for their use as a dual T₁-T₂ contrast agent for magnetic resonance imaging and as a probe for luminescent imaging in the near-infrared region.

Abstract

The world needs more environmentally friendly materials every time, especially when the application demands constant interaction with fragile habitats. The naval industry is a crucial player in a globalised economy, and the ambient impact of ships on the seas is well-known. Biofouling is one of the significant issues in this industry, and paints with biocides are used as the principal coating solution. However, those are mechanically poor, releasing heavy pollutants into the oceans. Multifunctional coatings obtained by PVD technology could help overcome this situation. The present study proposes a solution to create an advanced coating composed of zirconium nitride and copper in a specific nano-architecture. The developed coating was obtained in a hybrid magnetron co-sputtering system, employing high-power impulse and direct current power sources in a reactive atmosphere. SEM and TEM expose the morphology and the structure of the coatings. EDX, RBS, and XPS were used to assess the chemical insights of the coating. Halo and biofilm tests (with Cobetia marina) were employed to evaluate the antibiofouling action of the coating. The results showed that the activation of the coating, regardless of the used method, provoked the copper migration to the surface, being crucial to obtaining the antibacterial action (reduced bacteria adhesion and > 3 log reduction in CFU on the surface) without affecting the coating integrity (assessed by SEM), and not releasing heavy metals in a significant manner (< 2 log reduction CFU on supernatant). This opens the option of this kind of material, which is environmentally friendly, to be applied in real applications.

Abstract

Early results on the plasma deposition of dielectric thin films on acoustic wave (AW) activated substrates revealed a densification pattern arisen from the focusing of plasma ions and their impact on specific areas of the piezoelectric substrate. Herein, we extend this methodology to tailor the plasma deposition of metals onto AW-activated LiNbO₃ piezoelectric substrates. Our investigation reveals the tracking of the initial stages of nanoparticle (NP) formation and growth during the submonolayer deposition of silver. We elucidate the specific role of AW activation in reducing particle size, enhancing particle circularity, and retarding NP agglomeration and account for the physical phenomena making these processes differ from those occurring on non-activated substrates. We provide a comparative analysis of the results obtained under two representative plasma conditions: diode DC sputtering and magnetron sputtering. In the latter case, the AW activation gives rise to a 2D pattern of domains with different amounts of silver and a distinct size and circularity for the silver NPs. This difference was attributed to the specific characteristics of the plasma sheath formed onto the substrate in each case. The possibilities of tuning the plasmon resonance absorption of silver NPs by AW activation of the sputtering deposition process are discussed.

Abstract

Near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) experiments have been carried out in N-2 and N-2-H2O atmospheres on a Pt-based catalyst physically mixed with an Eu-doped ZrO2 ionic conductor as a function of temperature under realistic conditions of the water gas shift (WGS) reaction. This work aims to demonstrate the significant effect of having active H2O on the ionic conductor surface at reaction temperatures to provide it to Pt metal sites. The ionic conductor, Eu-doped zirconia matrix, presents defects (oxygen vacancies, O-v) that allows upon H2O dissociation the formation of a hydrogen-bonded molecular water layer favoring diffusion through a Grotthuss mechanism below 300 degrees C. In the presence of H2O, the O-v are occupied by hydroxyl species as observed in the Eu 4d spectra, which differentiate two types of Eu oxidation states. The Eu3+-to-Eu2+ atomic ratio increases with the occupancy of the O-v by hydroxyls. Moreover, while the Pt-based catalyst alone is unable to create Pt-OH bonds, the physical mixture of the Pt-based catalyst and the ionic conductor allows the formation of Pt-OH bonds from room temperature up to 300 degrees C. These data demonstrate that the increase in molecular water concentration on the ionic conductor surface up to 300 degrees C acts as a reservoir to provide water to the Pt surface, enhancing the catalyst performance in the WGS reaction, supporting the importance of the surface H2O concentration in the reaction kinetics.

Abstract

In recent years, significant advancements have occurred in our comprehension of amber consumption patterns in the Iberian Peninsula. This progress stems from the increasing volume of FTIR data related to both archaeological and geological amber. Consequently, a chronological model has been established, delineating amber consumption in the Iberian Peninsula from the Late Paleolithic to the Iron Age. Broadly, local amber consumption has been minimal since the Paleolithic period. Sicilian amber makes its appearance in Iberia around the 5th millennium BCE and fades away in the 2nd millennium BCE, giving way to Baltic amber, which has remained the sole source since then. The well-defined chronological model, the abundance of FTIR provenance data, and the infrequent association of amber with absolute or relative dates prompt us to explore whether provenance can serve as a chrono-cultural proxy for amber beads. This study introduces new amber finds, presents fresh FTIR data on archaeological amber ornaments, and incorporates minor updates and bug fixes to the general catalog. It is the outcome of a thorough bibliographic review and on-site analysis and examination of the beads. The results obtained in this study enable the reconstruction of amber consumption throughout Iberian prehistory, drawing on 29 newly FTIR-analyzed ambers from 9 sites. Our findings expand the empirical foundation, facilitating the confirmation of diachronic changes in amber consumption. Importantly, they affirm that amber provenance can indeed be employed as a viable chrono-cultural proxy.

Abstract

Research on high-field magnetic resonance imaging (HF-MRI) has been increased in recent years, aiming to improve diagnosis accuracy by increasing the signal-to-noise ratio and hence image quality. Conventional contrast agents (CAs) have important limitations for HF-MRI, with the consequent need for the development of new CAs. Among them, the most promising alternatives are those based on Dy3+ or Ho3+ compounds. Notably, the high atomic number of lanthanide cations would bestow a high capability for X-ray attenuation to such Dy or Ho-based compounds, which would also allow them to be employed as CAs for X-ray computed tomography (CT). In this work, we have prepared uniform NaDy(WO4)(2) and NaHo(WO4)(2) nanoparticles (NPs), which were dispersible under conditions that mimic the physiological media and were nontoxic for cells, meeting the main requirements for their use in vivo. Both NPs exhibited satisfactory magnetic relaxivities at 9.4 T, thus making them a promising alternative to clinical CAs for HF-MRI. Furthermore, after their intravenous administration in tumor-bearing mice, both NPs exhibited significant accumulation inside the tumor at 24 h, attributable to passive targeting by the enhanced permeability and retention (EPR) effect. Therefore, our NPs are suitable for the detection of tumors through HF-MRI. Finally, NaDy(WO4)(2) NPs showed a superior X-ray attenuation capability than iohexol (commercial CT CA), which, along with their high r(2) value, makes them suitable as the dual-probe for both HF-MRI and CT imaging, as demonstrated by in vivo experiments conducted using healthy mice.

Abstract

Intraband carrier relaxation in quantum dots (QDs) has been a subject of extensive spectroscopic investigation for several decades, and have been used to optimize the efficiency of opto-electronic processes. In the past few years, metal halide perovskites-based QDs have been shown to exhibit slow hot-carrier cooling characteristics that are desirable for photo-energy harvesting technologies. While several mechanisms are proposed to rationalize the retardation of the cooling dynamics, including hot-phonon bottleneck and polaronic effects, the role of inter-particle connectivity in these dynamics is largely ignored. Here, an in-depth study of photo-excitation dynamics and carrier cooling on perovskite QD solids with varying degrees of inter-dot coupling is presented. It is observed that inter-particle connectivity has deterministic effects on the many-body interactions that are relevant for carrier cooling. These include carrier-carrier interactions that result in Auger-reheating of the carriers, and lattice characteristics that subsequently affect the phonon-assisted cooling dynamics. This spectroscopic study of ultrafast carrier dynamics in perovskite QD solids establishes inter-dot separation as a critical material design parameter for the optimization of photo-generated carrier temperature, which fundamentally determines the luminescence characteristics and thus the opto-electronic quality of the material.

The photo-excitation dynamics and carrier cooling in metal halide perovskite quantum dot solids are investigated here. Evidence for the deterministic role of inter-particle connectivity on the many-body interactions relevant to carrier cooling is discussed. These include carrier-carrier interactions that result in Auger-reheating of the carriers, and lattice coupling that subsequently affects the phonon-assisted cooling dynamics. image

Abstract

Carbon is a critical material for existing and emerging energy applications and there is considerable global effort in generating sustainable carbons. A particularly promising area is iron-catalyzed graphitization, which is the conversion of organic matter to graphitic carbon nanostructures by an iron catalyst. In this paper, it is reported that iron-catalyzed graphitization occurs via a new type of mechanism that is called homogeneous solid-state catalysis. Dark field in situ transmission electron microscopy is used to demonstrate that crystalline iron nanoparticles “burrow” through amorphous carbon to generate multiwalled graphitic nanotubes. The process is remarkably fast, particularly given the solid phase of the catalyst, and in situ synchrotron X-ray diffraction is used to demonstrate that graphitization is complete within a few minutes.

Abstract

Solid-state oxide ion and proton conductors are garnering significant attention due to their high ionic conductivity and potential applications in a range of electrochemical devices, including solid oxide fuel cells and gas sensors. In this study, we report the influence of partial substitution of La³⁺ in isolated tetrahedral LaVO₄ ceramics with 0.01 mol of alkaline-earth metals Ca²⁺, Sr²⁺ and Ba²⁺ on the phase stability and electrical properties. It was found that acceptor doping effectively enhances mixed oxide ion and proton conductivities, with Sr²⁺ substitution yielding the highest conductivity, achieving ∼10⁻³ S cm⁻¹ at 900 °C under a wet O₂ atmosphere. DFT calculations and ab initio molecular dynamics simulations revealed that protons preferentially form hydrogen bonds with the lattice oxygen near the dopants and migrate through a continuous process of hopping and rotation between inter- and intra-tetrahedral VO₄ groups. Additionally, the existence of oxygen vacancies facilitates the formation of V₂O₇ dimers through sharing corners with adjacent isolated VO₄ tetrahedra, enabling ion exchange through a synergistic mechanism involving V₂O₇ dimer breaking and reforming. This research highlights the critical role of the deformation and rotational flexibility of isolated tetrahedral units in facilitating oxide ion and proton transport, underscoring the potential for developing mixed oxide ion and proton conductors in oxygen vacancy-deficient oxides with tetrahedral-based structures.

Abstract

Given the rapid advancements in artificial intelligence, there is an escalating demand for wearable sensors. An efficient graphene-based material synthesized from the mesophase pitch of waste slurry oil was integrated into a cost-effective piezoresistive pressure sensor consisting of a conductive film made of carbon nanotubes (CNTs), graphene, and Polydimethylsiloxane (PDMS). A simple fabrication approach has been suggested to infuse PDMS with CNTs-graphene, resulting in a pressure sensor exhibiting superior conductivity, enhanced sensitivity, and quick responsiveness to diverse pressure variations. Moreover, films containing varying percentages of graphene were compared. Scanning electron microscopy was utilized to examine the surface and structural characteristics of the CNTs-graphene-PDMS film, alongside studying the pressure sensor's sensing capabilities. Various applications were examined for both the individual sensor and the array of sensors. The findings demonstrate the successful detection of diverse human motions, Morse code recognition, and effective discernment of various pressures by the fabricated pressure sensor, indicating its potential for applications in smart devices, robotics, and wearable sensors.

Abstract

The discovery of a set of beads, comprising both Sicilian amber and resin-coated beads in the Middle Bronze Age burial site of Cova del Gegant (Sitges, Barcelona, Spain), has sparked inquiries into whether the coating was intended for imitation or counterfeiting of amber. We assert that human-made materials, such as bead coatings, are intentionally conceived, designed, and crafted to fulfill specific functions. Thus, for an object to effectively fulfill its intended purpose, it must meet particular performance criteria influenced by situational factors. This paper aims to construct an empirically grounded narrative elucidating the development and function of resin-coated bead technology. Our methodology includes a comprehensive quantitative analysis of the coating and beads, an exploration of the interplay between technical choices and situational factors, and an investigation into whether the simulation of sensory performance characteristics played a pivotal role in the concept and design of resin-coated beads. Additionally, we synthesize data to unveil broader patterns related to the crafting and utilization of resin-coated and amber beads across time and space. We have documented resin-coated beads in the Iberian Peninsula from the Neolithic period (5th to 3rd millennia BCE) until at least the Middle Bronze Age (first half of the 2nd millennium BCE), where they coexisted with amber beads. Analysis employing ATR-FTIR and mu-CT imaging has revealed a composite coating comprising pine resin, beeswax, and carotene, adhered to shell beads with bone glue. This composite material represents the earliest known development in human history, unique to the Iberian Peninsula and without parallel in Prehistoric Europe. Our examination of the performance characteristics and functional roles of resin-coated beads suggests their potential as substitutes for amber beads, particularly in regions where amber was scarce or inaccessible. Despite being crafted from commonplace materials, these coated beads exhibit intentional design choices likely aimed at simulating the visual performance characteristics of amber. This deliberate effort, alongside their widespread distribution across time and space, indicates that composite-coated beads held symbolic and social significance akin to amber beads.

Abstract

Water quality and usability are global concerns due to microbial and chemical pollution resulting from anthropogenic activities. Therefore, strategies for eliminating contaminants are required. In this context, the removal and decrease in antibiotic activity (AA) associated with levofloxacin (LEV), using TiO₂ and Ag/TiO₂ catalysts, with and without sunlight and peroxydisulfate, was evaluated. Additionally, the disinfection capacity of catalytic systems was assessed. The catalysts were synthesized and characterized. Moreover, the effect of Ag doping on visible light absorption was determined. Then, the photocatalytic treatment of LEV in water was performed. The materials characterization and EPR analyses revealed that LEV degradation and AA decrease were ascribed to a combined action of solar light, sulfate radical, and photocatalytic activity of the TiO₂-based materials. Also, the primary byproducts were elucidated using theoretical analyses (predictions about moieties on LEV more susceptible to being attacked by the degrading species) and experimental techniques (LC-MS), which evidenced transformations on the piperazyl ring, carboxylic acid, and cyclic ether on LEV. Moreover, the AA decrease was linked to the antibiotic transformations. In addition, the combined system (i.e., light/catalyst/peroxydisulfate) was shown to be effective for E. coli inactivation, indicating the versatility of this system for decontamination and disinfection.

Abstract

This paper deals with the effect of hydroxylated boron nitride nanosheets (BNNS) incorporation on the microstructural and mechanical features of zirconia ceramics. Few-layered BNNS were synthesized via a simple hydroxide-assisted planetary ball milling exfoliation technique. 3 mol% yttria tetragonal zirconia polycrystal (3Y-TZP) with 2.5 vol% BNNS powders were prepared by an environmentally friendly process in water, and spark-plasma sintered at three temperatures to explore the in-situ reduction of the functionalized BNNS. An exhaustive study by (S)TEM techniques was performed to elucidate the influence of the sintering temperature on the matrix and the 3Y-TZP/BNNS interfaces, revealing that BNNS were homogeneously distributed throughout the matrix with an abrupt transition at 3Y-TZP/BNNS interfaces. BNNS effectively hindered slow crack growth, thus increasing the composite's crack growth resistance by about 30 %. A 1 MPa·m^1/2 rising R-curve was also induced by crack bridging.

Abstract

There is relevant interest concerning beehives, taking into account climate change and its influence on bees’ behavior. A part of the industrial engineering sector is focusing on beekeeping applications. More specifically, the present study aims to develop a trailer for the transport of beehives adapted to be placed or fixed to a tractor or a vehicle trailer, with the objective of transporting the beehives safely and stably during transhumance. The proposed novel design relates to a trailer that incorporates a device for housing a rectangular section of the beehives, which can be adapted for fixing or housing in a vehicle or in a vehicle trailer. The device comprises a lower support structure, adapted to support a plurality of rectangular sections of beehives stacked horizontally on the lower structure, an upper frame adapted to house the beehives inside, and two or more connecting elements between the lower structure and the upper frame. The connection of the trailer with the device facilitates the loading and unloading of the beehives by mechanical means. The different parts have been designed as individual pieces and then assembly is carried out to achieve the complete design. This method of implementation is because the simulation of individual components is simpler and easier, since if it is carried out through assembly, the type of joint, such as welding, and the length of the weld would have to be indicated at each point of contact between components, along with its thickness and all the necessary parameters. Therefore, in those welding points, fixed fastenings are indicated and so will simplify it. In accordance with the individual creation of each part, its own load simulation has been carried out. Static analyses are performed taking into account structural elements of this proposed design, with restrictions and loads being established. The analysis, including upper bars and supports, has been completed with several situations. Based on stress values, deformations have been determined and calculations evaluated. The trays have been manufactured using flat steel bars and angled bars for the legs and support of the hives.

Abstract

A biocermet made of zirconia/20 vol% tantalum (3Y-TZP/Ta) is a new composite with exceptional capabilities due to a combination of properties that are rarely achieved in conventional materials (high strength and toughness, cyclic fatigue resistance and flaw tolerance, wear resistance, corrosion resistance, electrical conductivity, etc.). In this study, for the first time, the biomedical performance of a 3Y-TZP/Ta biocermet was evaluated in detail. Its in vitro biocompatibility was assessed using mesenchymal stem cell culture. The effectiveness of in vivo osteointegration of the biocermet was confirmed 6 months after implantation into the proximal tibiae of New Zealand white rabbits. In addition, the possibility of using magnetic resonance imaging (MRI) for medical analysis of the considered biocermet material was studied. The 3Y-TZP/Ta composite showed no injurious effect on cell morphology, extracellular matrix production or cell proliferation. Moreover, the implanted biocermet appeared to be capable of promoting bone growth without adverse reactions. On the other hand, this biocermet demonstrates artefact-free performance in MRI biomedical image analysis studies, making it more suitable for implant applications. These findings open up possibilities for a wide range of applications of these materials in orthopedics, dentistry and other areas such as replacement of hard tissues.

Abstract

En este trabajo, la Titania se modificó por sulfatación o fluorización y platino en superficie, con el objetivo de mejorar la eficiencia en la reducción de Cr (VI) en comparación con el material TiO2 base sintetizado por el método sol-gel. Los materiales fueron caracterizados por DRX, SBET, UV-Vis DRS, FRX, TEM, FTIR y XPS. Las modificaciones permitieron obtener una mayor estabilidad en la fase Anatasa y en el área superficial del semiconductor. La adición de F y Pt en el TiO2 provocaron aumentos de absorción en la región visible del espectro electromagnético. Se observó una correlación entre las nuevas propiedades fisicoquímicas obtenidas tras la modificación del TiO2 y el rendimiento fotocatalítico del material. El mejor resultado en la reducción de cromo se obtuvo utilizando Pt-S-TiO2 como fotocatalizador, este material mostró una combinación adecuada de área superficial, alta absorción UV-Vis, alta hidroxilación y la existencia de nanopartículas de Pt en la superficie que favorecen un aumento de la vida media del par electrón-hueco. También se evaluaron parámetros de reacción que demostraron que el mejor desempeño fotocatalítico se obtuvo bajo atmósfera de N2, intensidad de luz de 120 W/m2 y 2 horas de tiempo total de reacción. Así mismo, se observó que aumentar el tiempo de reacción de 2 a 5 horas tuvo un efecto perjudicial sobre la eficiencia en la reducción de Cr (VI).

Abstract

This study focused on the development of vanadium-based catalysts for formic acid production from glucose. The influence of different vanadium precursors on the catalytic activity of titania supported catalysts was contemplated and compared to the performance of commercial and synthesized unsupported V2O5. The obtained results reveal a successful deposition of multiple vanadium species on TiO2 as confirmed by XRD, Raman, and UV-Vis measurements. Catalyst screening identifies V5+ species as main player indicating its important oxidizing potential. Afterwards, the key reaction conditions, as temperature, time, pressure and catalyst loading, were optimized as well as the state of the catalyst after the reaction characterized.

Abstract

The ability to control the porosity of thin oxide films is a key factor determining their properties. Despite the abundance of dry processes for synthesizing oxide porous layers, a high porosity range is typically achieved by spin-coating-based wet chemical methods. Besides, special techniques such as supercritical drying are required to replace the pore liquid with air while maintaining the porous network. In this study, we propose a new method for the fabrication of ultraporous titanium dioxide thin films at room or mild temperatures (T <= 120 degrees C) by a sequential process involving plasma deposition and etching. These films are conformal to the substrate topography even for high-aspect-ratio substrates and show percolated porosity values above 85% that are comparable to those of advanced aerogels. The films deposited at room temperature are amorphous. However, they become partly crystalline at slightly higher temperatures, presenting a distribution of anatase clusters embedded in the sponge-like open porous structure. Surprisingly, the porous structure remains after annealing the films at 450 degrees C in air, which increases the fraction of embedded anatase nanocrystals. The films are antireflective, omniphobic, and photoactive, becoming superhydrophilic when subjected to ultraviolet light irradiation. The supported, percolated, and nanoporous structure can be used as an electron-conducting electrode in perovskite solar cells. The properties of the cells depend on the aerogel-like film thickness, which reaches efficiencies close to those of commercial mesoporous anatase electrodes. This generic solvent-free synthesis is scalable and applicable to ultrahigh porous conformal oxides of different compositions, with potential applications in photonics, optoelectronics, energy storage, and controlled wetting.

Abstract

Research on personal adornments depends on the reliable characterisation of materials to trace provenance and model complex social networks. However, many analytical techniques require the transfer of materials from the museum to the laboratory, involving high insurance costs and limiting the number of items that can be analysed, making the process of empirical data collection a complicated, expensive and time-consuming routine. In this study, we compiled the largest geochemical dataset of Iberian personal adornments (n = 1243 samples) by coupling X-ray fluorescence compositional data with their respective X-ray diffraction mineral labels. This allowed us to develop a machine learning-based framework for the prediction of bead-forming minerals by training and benchmarking 13 of the most widely used supervised algorithms. As a proof of concept, we developed a multiclass model and evaluated its performance on two assemblages from different Portuguese sites with current mineralogical characterisation: Cova das Lapas (n = 15 samples) and Gruta da Marmota (n = 10 samples). Our results showed that decisi & oacute;n-tres based classifiers outperformed other classification logics given the discriminative importance of some chemical elements in determining the mineral phase, which fits particularly well with the decision-making process of this type of model. The comparison of results between the different validation sets and the proof-of-concept has highlighted the risk of using synthetic data to handle imbalance and the main limitation of the framework: its restrictive class system. We conclude that the presented approach can successfully assist in the mineral classification workflow when specific analyses are not available, saving time and allowing a transparent and straightforward assessment of model predictions. Furthermore, we propose a workflow for the interpretation of predictions using the model outputs as compound responses enabling an uncertainty reduction approach currently used by our team. The Python-based framework is packaged in a public repository and includes all the necessary resources for its reusability without the need for any installation.

Abstract

Fischer-Tropsch Synthesis (FTS) allows the conversion of syngas to high-density liquid fuels, playing a key role in the petrochemical and global energy sectors over the last century. However, the current Global Challenges impose the need to recycle CO2 2 and foster green fuels, opening new opportunities to adapt traditional processes like FTS to become a key player in future bioenergy scenarios. This review discusses the implementation of CO2- 2- rich streams and in tandem catalysis to produce sustainable fuels via the next generation of FTS. Departing from a brief revision of the past, present, and future of FTS, we analyse a disruptive approach coupling FTS to upstream and downstream processes to illustrate the advantages of process intensification in the context of biofuel production via FTS. We showcase a smart tandem catalyst design strategy addressing the challenges to gather mechanistic insights in sequential transformations of reagents in complex reaction schemes, the precise control of structure-activity parameters, catalysts aging-deactivation, optimization of reaction parameters, as well as reaction engineering aspects such as catalytic bed arrangements and non-conventional reactor configurations to enhance the overall performance. Our review analysis includes technoeconomic elements on synthetic aviation fuels as a case of study for FTS applications in the biofuel context discussing the challenges in market penetration and potential profitability of synthetic biofuels. This comprehensive overview provides a fresh angle of FTS and its enormous potential when combined with CO2 2 upgrading and tandem catalysis to become a front-runner technology in the transition towards a low-carbon future.

Abstract

Laser-induced graphene (LIG) on paper is a popular choice for fabricating flexible micro-supercapacitors (MSCs) as it is a simple and sustainable process. However, carbon-based MSC electrodes have limited energy densities. To address this challenge, this study presents a highly reproducible and cost-effective method for decorating manganese oxide (MnOx) x ) on interdigital LIG MSC electrodes, fabricated via a single-step direct laser writing (DLW) process on paper substrates. The paper fibers embedded with MnOx x precursors are transformed into graphene through laser processing while reducing the salt, resulting in the formation of MnOx-LIG. x-LIG. The resulting MnOx-LIG-MSC x-LIG-MSC exhibits a specific capacitance of 12.30 mF cm- 2 (0.05 mA cm- 2 ) with a 60 % retention at 1000 bending cycles (30 degrees), degrees ), due to the pseudocapacitive contribution of MnOx. x . Furthermore, the devices exhibit high electrochemical stability, retaining 190 % of the initial specific capacitance after 10,000 cycles, and a high energy density of 2.6 mu Wh cm-- 2 (at a power of 0.109 mW cm-- 2 ). The study demonstrates that manganese oxide- based LIG-MSCs have the potential to be used as energy storage devices for portable, low-cost, and flexible paper electronics.

Abstract

In this work, the influence of the aspect ratio of graphene-based nanostructures (GBNs) and content on the mechanical properties of 3 mol% yttria tetragonal zirconia polycrystalline 3Y-TZP matrix composites was analysed. The influence of the dispersion method and sintering parameters on the flexural strength and elastic modulus of the composites was studied, and the fracture surfaces were characterized to determine the fracture mechanisms that occur. The results showed that small amounts of exfoliated graphene nanoplatelets, with reduced lateral size, and few layer graphene, up to 1.0 and 2.5 vol%, respectively, slightly increase the 3Y-TZP flexural strength. This has been attributed to the tortuosity of the crack propagation pathways and strengthening mechanisms. Higher contents cause a decrease in flexural strength and stiffness because of overlapped GBNs, which can promote the crack propagation. The pull-out of GBN was more significant in composites with non-exfoliated graphene nanoplatelets, where no increase on the flexural or biaxial strength was measured.

Abstract

LDH-derived Ni-based catalysts are gathering momentum due to their excellent thermal stability but their lowtemperature CO2 methanation is limited. In this study, various concentrations of La were introduced into the LDH-derived Ni-based catalysts for CO2 methanation, and the underlying mechanisms were investigated. The optimal Ni/La-0.2-MgAlOx catalyst presented a CO(2)conversion level of 69.0 % at 225 C-degrees, which is over 7 times higher than that of conventional Ni/MgAlOx. The addition of small amounts of La could significantly enhance H spillover to promote the reduction of Ni species, but the oxygen vacancy concentration became the dominant factor causing changes in low -temperature activity as the La contents continue to increase. CO2 was found to be adsorbed at the oxygen vacancies in the form of bidentate carbonates, which are more reactive under an enhanced electron -rich environment. The research offers guidance to design effective and sustainable catalysts for low -temperature CO2 methanation.