Antonio Riveiro Rodriguez

Bioactive Glasses The unique characteristics of lasers enable the transformation of bioactive glasses into diverse functional architectures, including coatings, nanoparticles, nanofibres for wound dressings, and scaffolds for bone regeneration. More details can be found in the Review Article by Antonio Riveiro, Juan Pou, and co-workers (DOI: 10.1002/adhm.202503610).

Lithium orthosilicate (Li4SiO4) has demonstrated a high CO2 adsorption rate and capacity and its suitability to be implemented in industry as CO2 capture technology at high temperatures. The optimum solid adsorbent should present a porous structure to maximize surface and enable a high sorption rate. In this work, we present an original approach based on the use of a novel architecture of precursors in the form of very thin free-standing solid silica fibers. An original technique called continuous fiberizing by laser melting (Cobiflas) was used to obtain membranes of pure silica fibers with diameters in the micrometer range, forming a porous membrane which offer a high surface and porous connectivity to be used as precursors without any supporting substrate. Then, we employed a method based on the impregnation of the silica fibers within a lithium-containing aqueous solution and subsequent calcination to obtain a porous solid adsorbent with the maximum proportion of lithium orthosilicate. This method is compared with the results obtained using a sol-gel powder method by analyzing their composition using X-Ray Diffraction (XRD), and their adsorption capacity and adsorption kinetics by Thermogravimetric analyses (TGA). As a result, an outstanding type of solid adsorbent is reported with a 31% adsorption capacity and a total regeneration capacity, which is over 0.8 efficiency with regard to the theoretical maximum adsorption of this material.

Dew Water Harvesting by Laser Micropatterning A metallic surface micropatterned with a laser achieves self-cooling capacity when it faces the night sky thanks to its enhanced infrared emissivity, which triggers water condensation similar to natural dew on leaves. The patterned microgrooves promote condensation as a continuous film rather than dispersed droplets, enabling an efficient and autonomous harvesting of dew water. More details ban be found in article number 2419472 by Pablo Pou-Álvarez and co-workers.

Aluminium alloys are widely used in many industrial sectors due to their high strength-to-weight ratio. The structural integrity of aluminium components is a fundamental issue when these components are subjected to fatigue loading. Some surface treatments such as shot peening, or laser shock peening can induce compressive residual stresses in the treated material and thus may be effective at delaying crack propagation. In this research, the fracture toughness of a 6060 T6 aluminium alloy was evaluated according to ASTM E1820 standard. SE(B) specimens were analysed in the non-treated condition and after different shot peening treatments. The crack propagation behaviour of these specimens was evaluated during the fatigue precrack stage of the tests by fitting the crack growth rates to Paris law. Then, a fracture toughness value was determined using the resistance curve procedure method. The results of these tests demonstrated that the shot peening treatments had little or no significant effect on the fracture toughness values, or the crack propagation rates. The reason behind these results is probably the shallow depth of the strain hardened layer affected by the shot peening treatments.

The present work explores a unique yet unexplored synergy between the properties of laser micropatterned metallic surfaces and the requirements for an autonomous dew water harvesting candidate material. Laser-patterned aluminum surfaces achieved simultaneously high infrared emissivity (up to 0.95 in the atmospheric window) and superhydrophilic wettability (water contact angle of 0°), key properties enabling passive radiative cooling and filmwise condensation dynamics respectively. The generation of micrometric-sized grooves during laser processing plays a fundamental role in both properties, as they provide a broadband enhancement of the emissivity based on multiscale topographies and oxide layers, while limiting the growth of the water film during condensation through strong capillary wicking forces. As a result, the patterned aluminum surfaces display self-cooling capacities under radiative deficit conditions as well as low water retention levels (three times lower than the untreated dropwise condensation counterparts). The promising results obtained lead to the construction and evaluation of a real size outdoors autonomous dew water harvesting system based on those surfaces, demonstrating the scalability of the technology. A 70% improvement in the collected dew water in comparison to a state-of-the-art reference material is consistently measured during 1-year outdoor study, proving the robustness of the surfaces and their performance.

• Bimetallic Pd/CuO NPs were obtained by laser re-irradiation in liquid. • Laser re-irradiation of Pd and CuO NPs in water produced alloyed Pd/CuO NPs. • The presence of Pd in the Pd/CuO bimetallic nanoparticles modulated the toxicity of Cu. • Bimetallic Pd/CuO NPs showed good antibacterial properties against S. aureus . • Bimetallic Pd/CuO showed proper cytobiocompatibility in human fibroblast cells. Antimicrobial resistance (AMR) is considered a major global health problem of the 21st century. Noble metal nanoparticles (NPs) have attracted increasing attention as a promising tool to fight against resistant infections. In this research, we explore bimetallic NPs, as they can give rise to further and improved physicochemical and biological properties. In this work, monometallic Cu/CuO and Pd NPs were synthesized by laser ablation. Afterwards, these NPs were mixed and the resulting colloidal solution was multiply re-irradiated with the aim of producing Pd/CuO bimetallic NPs. All the NPs presented rounded shape and crystalline microstructure. Although the re-irradiated NPs contained both precursor materials, all characterization techniques agreed on the occurrence of an intermetallic alloy of both materials, Cu 3 Pd, that is concluded to be formed as a consequence of the interaction between the laser beam and the mixture of monometallic NPs. With the objective of studying antimicrobial activity against Staphylococcus aureus , the CuO NPs, Pd NPs and Pd/CuO NPs were immobilized on the surface of titanium discs. Ion release was tracked during the first 24 h and cytotoxicity of the immobilized NPs was as well tested with HFF-1 human fibroblast cell line. Bimetallic Pd/CuO NPs showed a significant inhibitory effect on S. aureus and no toxic impact on fibroblasts.

Laser-based manufacturing technologies have consolidated their key position among competitor manufacturing technologies thanks to the elevated level of accuracy, productivity, consistency, and flexibility provided by the advances in laser technology (e [...]

The understanding of the mechanical properties in glass nanofibers remains a challenge. As the fiber diameter decreases, surface-to-volume atom fraction increases, making the impact of surface defects more significant. To elucidate these effects, we employed classical molecular dynamics (MD) simulations to investigate how fiber dimensions and the surface layer influence the mechanical properties of silica glass nanofibers. Our simulation methodology included fibers of varying diameters, generated using two different production methods (i.e. "cutting" and "casting" methods) that produce different degrees of surface atomic defects, and compared with bulk samples without surface atoms. The defect-rich surface layer of these fibers was carefully analyzed. Then, MD tensile simulations were performed to analyze the effect of the fiber surface on the mechanical properties and to explain the onset of the brittle-to-ductile transition experimentally observed at a few tens of nanometers. The results revealed that the surface layer maintains a fixed thickness independent of the fiber diameter, resulting in a pronounced increase of the fiber defects in thin fibers. Also, the tensile test simulations show that surface defects significantly reduce tensile strength, without appreciably increasing ductility compared to bulk samples. In turn, we show that the brittle-to-ductile transition is not caused by the surface defects, but related to a balance between fracture energy and elastic energy, which varies with fiber length. Using experimental values of different glass properties, our theory predicted a threshold length of around 200 nm, below which ductile fracture dominates, in reasonable agreement with experimental results.

This study explores the potential of laser surface modification (LSM) to enhance the biological properties of melt-derived bioactive glasses, specifically 45S5 and ICIE16, which are key in medical implants due to their bone-regenerating capabilities. Despite their bioactivity, these materials have limitations in cellular adhesion due to their smooth surfaces. LSM enables the creation of precise surface patterns that could improve interactions with biological environments. This study involved surface texturing bioactive glass (BG) samples using CO2 and femtosecond (fs) laser systems, modifying the laser average power, scanning speed, line spacing, and number of passes. Characterization methods included optical and stereoscopic microscopy, profilometry, and solubility tests in Tris-HCl buffer to evaluate surface roughness evolution, morphology, and bioactive behavior. The findings demonstrated significant modifications in surface properties post-texturing. The CO2 laser-treated surfaces preserve the increased roughness values after 75 days of immersion in Tris-HCl buffer for both 45S5 and ICIE16 melt-quenched bioactive glasses, showing a potential long-term osteoconductivity enhancement. On the contrary, the femtosecond laser-treated surfaces revealed a preferential apatite precipitation ability at the pattern grooves. Femtosecond laser modification stands as a suitable technique to provide preferential osteoconductivity characteristics when conducted on the surface of bioactive glass with moderate reactivity, such as ICIE16 bioactive glass.

Abstract In fiber reinforced composite materials, the interfacial strength between the fibers and the matrix plays a key role in controlling the stress transfer and damage mechanisms of the composite. In this study, CO 2 laser surface treatment of the fibers was investigated as a potential sustainable substitute for conventional chemical treatments, that can be costly and have negative environmental effects. The influence of the laser treatment on basalt fiber fabric was comprehensively investigated. The fibers were subjected to different laser power levels and characterized from a morphological and mechanical point of view. From optical and scanning electron microscopy, it was observed that the treated fibers manifested increased surface roughness along with spots of fused and bonded fibers. Individual treated fibers exhibited improved tensile properties with increased values of scale parameter (by about 21%) in the case of a laser power equal to 1.04 W/mm 2 , and no substantial changes in Young's modulus. The treated fibers were subsequently used in the preparation of epoxy‐based microcomposites, and microdebonding tests revealed an increase in the interfacial shear strength (IFSS) up to 8%. Therefore, this work proved that a laser surface treatment of basalt fibers is a valid alternative to conventional fiber surface modification to enhance the mechanical compatibility between fibers and matrix, and therefore to improve the mechanical performances of basalt fiber composites. Highlights Failure in composites due to weak interfacial adhesion with epoxy. CO 2 laser treatment of basalt fibers to enhance interfacial adhesion. Treated fibers exhibit improved tensile properties. Treated fibers manifested improved interfacial shear strength (IFSS, +8%).

The aim of this work is to investigate the formation of an anomalously high fraction of twin boundaries (TBs) during laser directed energy deposition (DED) of a Mg-3Al-1 Zn (wt.%) alloy. With that goal, single tracks are deposited using different combinations of scan speed and powder feed rate. The melt pool dimensions are related to the DED parameters. Irrespective of the processing conditions, the resulting microstructures are always formed by fine grains with a very weak texture. However, some DED parameter combinations give rise to a fraction of TBs that is significantly higher than that corresponding to a random texture. These TBs are characterized by an irregular morphology and by the presence of segregated atoms, solute clusters, and nanoparticles. Additionally, the lattice in the vicinity of the TBs is highly distorted and contains a high population of stacking faults. All these characteristics set them apart from conventional tensile TBs, which exhibit a large degree of coherency and limited segregation. Rapid solidification is thus presented here as a novel avenue to design TBs with unique properties in Mg alloys. This work paves the way for future studies on grain boundary design via additive manufacturing methods, a field that is still in its infancy.

Shot peening is generally used to improve the fatigue performance of mechanical components. However, identifying the geometrical and mechanical characteristics of the shots that improve fatigue strength is still a challenging task, as there are many variables involved in the shot peening process. The present work addresses the effect of different shot media on the fatigue behaviour of an aluminium alloy 6082 T6. Four different shot types were used: silica microspheres, alumina shots, aluminium cut wire and zinc cut wire. Axial fatigue tests were carried out to obtain the Wöhler curves corresponding to each shot peening treatment. The surface properties of the shot-peened specimens, such as grain size, hardness, residual stress and roughness were measured to determine their effect on the fatigue results. The fatigue results revealed that silica and zinc shots increased significantly the fatigue life of the alloy, whereas alumina and aluminium shots reduced its fatigue strength. Almen intensities have shown to correlate well with grain refinement and strain hardening. However, better fatigue results were obtained with the shots that generated higher surface compressive residual stresses. It is believed that small and smooth shots are preferable to sharp and irregular ones, regardless of the Almen intensity or surface hardness attained with the latter.

Introduction and Methods: Chronic wounds are a major healthcare problem, but their healing may be improved by developing biomaterials which can stimulate angiogenesis, e.g. by activating the Hypoxia Inducible Factor (HIF) pathway. Here, novel glass fibres were produced by laser spinning. The hypothesis was that silicate glass fibres that deliver cobalt ions will activate the HIF pathway and promote the expression of angiogenic genes. The glass composition was designed to biodegrade and release ions, but not form a hydroxyapatite layer in body fluid. Results and Discussion: Dissolution studies demonstrated that hydroxyapatite did not form. When keratinocyte cells were exposed to conditioned media from the cobalt-containing glass fibres, significantly higher amounts of HIF-1α and Vascular Endothelial Growth Factor (VEGF) were measured compared to when the cells were exposed to media with equivalent amounts of cobalt chloride. This was attributed to a synergistic effect of the combination of cobalt and other therapeutic ions released from the glass. The effect was also much greater than the sum of HIF-1α and VEGF expression when the cells were cultured with cobalt ions and with dissolution products from the Co-free glass, and was proven to not be due to a rise in pH. The ability of the glass fibres to activate the HIF-1 pathway and promote VEGF expression shows the potential for their use in chronic wound dressings.

Nanomaterials, defined as materials with typical dimensions of less than 100 nm in at least one dimension, exhibit very special physicochemical properties that are highly dependent on their size and shape [...].

In this study, the axial fatigue behaviour of hot forging tool steels at room temperature was investigated. Fatigue tests were performed on two steels within the same H13 specification. The fatigue tests were carried out in the high-cycle fatigue domain under normal conditions. These tests were also performed on specimens in contact with a corrosive medium, applying stress values that led to the high-cycle fatigue domain under normal conditions for the sake of comparison. Both materials showed similar fatigue strengths when they were tested under normal conditions. In contrast, corrosion fatigue lives were much lower than in normal tests and differed significantly between the two steels. Crack initiation was triggered by microstructural and surface defects in the normal tests, whereas the formation of corrosion pits caused crack initiation in the corrosion fatigue tests. Moreover, a fracture surface analysis revealed dissimilar crack propagation areas between both steels, which suggested that both steels had different fracture toughness. These results were in line with the differences observed between the carbide and grain sizes of both of the material microstructures.