Laser microtexturing is a promising technique to enhance the limited durability of forging tools by generating reservoirs capable of trapping lubricant particles, thus reducing friction even under hot working conditions. This work aims to evaluate the effects of laser microtexturing variables on the surface properties and wear resistance of AISI H13 hot forging tool steel. For the first time, the application of laser microtexturing treatments was performed on H13 steel in three heat treatment conditions: annealing without subsequent heat treatment, quenching and tempering, and nitriding after quenching and tempering. The effects of laser intensity, scanning speed, pitch, and number of passes on roughness, hardness, and wettability were analysed for each heat treatment condition. Roughness increased when using higher laser intensity and number of passes, or lower scanning speed, whereas the surface hardness was barely altered by laser treatments. Moreover, the treatments that produced higher roughness improved surface wettability for forging lubricants, and the grooves generated through laser treatments effectively retained graphite particles from hot forging lubricants, which is expected to be beneficial for the tribological behaviour of hot forging tools. Wear tests in a lubricant medium at room temperature revealed that treatments with lower heat inputs and larger pitches led to reduced mass losses. Finally, the major novelty of this work is the development, for the first time, of ring compression tests on laser-microtextured tools to evaluate friction under hot forging conditions. These tests revealed a clear decrease in the coefficient of friction in textured samples compared to non-textured ones, especially when using higher scanning speeds or larger pitches. Overall, this work provides new insights into improving the tribological performance of hot forging tools through laser microtexturing treatments.

Magnesium alloys are attractive materials in many sectors such as the automotive or the aerospace due to their impressive strength-to-weight ratio. However, the applications of magnesium alloys in these sectors demand high fatigue strength. Shot peening is widely used to improve the fatigue behaviour of metallic materials, but magnesium alloys are susceptible to overpeening due to their low hardness, which can hinder the improvement of fatigue behaviour. This research work aims to study the effects of fine particle shot peening treatments on the surface properties and fatigue life of a magnesium alloy AZ31B. These shot peening treatments induced twinning and grain refinement at the surface of the alloy, which is beneficial for the mechanical properties. A factorial design was developed in order to analyse the influence of Almen intensity and coverage on the roughness, wettability, hardness, residual stress and fatigue life of the alloy, and regression models were calculated for each response variable. Higher Almen intensities led to higher roughness values and more wettable surfaces, but coverage had no significant effect on these variables. Surface hardness and compressive residual stresses increased when using either high intensities or high coverages. Regression models were calculated and allowed to predict these experimental results with adjusted-R2 values higher than 0.90. Moreover, a significant regression model of fatigue life was obtained as a function of Almen intensity and coverage. The use of lower Almen intensities increased the range of coverage values that maximized the fatigue life of the alloy. The optimal shot peening parameters turned out to be an Almen intensity not higher than 0.05 mm A and coverage between 200% and 300%. At such conditions, fatigue life increased by a factor as high as 100 with respect to the non-treated alloy.

Introduction: Type II odontoid process fractures are common in the adult population, and anterior screw fixation aims to restore C1-C2 complex stability while preserving cervical motion. This study focuses on the numerical analysis of odontoid fractures, evaluating the structural behavior after anterior screw fixation using finite element simulations. Methods: Forty-eight patients (males, females, 74 years old on average) diagnosed with type II odontoid fractures and treated surgically between 2015 and 2023 were included in the study. Various loading conditions (magnitude and direction) were simulated to analyze displacements and stress distributions after screw insertion. Results: Screw fixation significantly fixes fractured vertebrae, but stress and deformation are considerably larger than in unfractured cases. Posterior oblique loads produced the highest stress concentrations, particularly at the base of the odontoid and the screw-bone interface. Male models exhibited greater total deformations and stresses under the same loading conditions, suggesting relevant biomechanical differences based on sex. Conclusions: Anterior odontoid screw fixation provides effective stabilization in type II odontoid fractures, although its performance depends on factors such as load vector and patient-specific anatomical characteristics. These findings support the use of FEM simulation as a valuable tool for personalized surgical analysis.

Introducción Las lesiones tumorales e infecciosas del peñasco representan un desafío quirúrgico debido a su ubicación profunda y proximidad a estructuras neurovasculares críticas. La petrosectomía retrosigmoidea intradural inframeatal (IIRP) es una vía alternativa que permite el acceso directo al ápice petroso con mínima morbilidad. Métodos Estudio retrospectivo de 11 pacientes sometidos a IIRP entre 2015 y 2025 en 2 hospitales del sur de Galicia. Se recogieron variables demográficas, tipo de lesión, tiempo quirúrgico, grado de resección, complicaciones y supervivencia libre de progresión. Se realizó un análisis descriptivo y una curva de Kaplan-Meier. Resultados Se incluyeron 11 pacientes (7 mujeres y 4 hombres; edad media de 48,9 años). Las lesiones incluyeron colesteatoma invasivo (n=4), meningiomas petroclivales (n=2), condrosarcoma (n=1), schwannoma atípico (n=1), carcinoma escamocelular (n=1), metástasis de cáncer de mama (n=1) y un absceso intraóseo por Actinomyces (n=1). Se logró una resección total macroscópica en el 81,8% de los pacientes, con una complicación transitoria (9,1%) y una recurrencia. El análisis de supervivencia libre de progresión mostró una supervivencia libre de recurrencia satisfactoria hasta 20 meses. Conclusión La IIRP es una técnica segura, eficaz y versátil para el abordaje de lesiones seleccionadas del peñasco. Permite una exposición adecuada con baja morbilidad y también es útil en casos infecciosos refractarios.

Bioactive glasses and lasers have followed a relatively similar path. Lasers and bioactive glasses began their journey in the second half of last century. It was in 1960 when Dr. Theodore H. Maiman constructed the first laser and fascinated the world with that marvellous ray. It was in 1967 when a young associate professor, Larry L. Hench, was addressed by a colonel returned from Vietnam, that asked him about developing a material that could help his soldiers recover from severe bone injuries. Two years later, the first bioactive material, the Bioglass, was launched. From there, the development of lasers and bioactive glasses has been extraordinaire. From the very first laser, the red ruby laser, different types of lasers in terms of wavelength, power, mode of functioning, etc. have been developed during the last decades. In a similar way, starting with the 45S5 silicate-based Bioglass many different bioactive glass formulations, including distinct active ions have been explored. This paper attempts to provide insight into these points of interaction, where the application of different types of lasers on distinct formulations of bioactive glass has allowed the transformation of bioactive glass for use as coatings, as three-dimensional implants, or the production of nanofibers.

Introduction: Tumorous and infectious lesions of the petrous bone pose a surgical challenge due to their deep location and proximity to critical neurovascular structures. Inframeatal intradural retrosigmoid petrosectomy (IIRP) is an alternative route that allows direct access to the petrous apex with minimal morbidity.Methods: Retrospective study of 11 patients who underwent IIRP between 2015 and 2025 in two hospitals in southern Galicia. Demographic variables, type of lesion, surgical time, degree of resection, complications, and progression-free survival were collected. A descriptive analysis and Kaplan-Meier curve were performed.Results: Eleven patients were included (7 women, 4 men; mean age 48.9 years). Lesions included invasive cholesteatoma (n=4), petroclival meningiomas (n=2), chondrosarcoma (n=1), atypical schwannoma (n=1), squamous cell carcinoma (n=1), breast cancer metastasis (n=1) and an intraosseous abscess due to Actinomyces (n=1). Gross total resection was achieved in 81.8%, with one transient complication (9.1%) and one recurrence. Progression-free survival analysis showed satisfactory recurrence-free survival up to 20 months.Conclusion: IIRP is a safe, effective, and versatile technique for approaching select lesions of the petrous bone. It allows sufficient exposure with low morbidity and is also useful in refractory infectious cases.

BACKGROUND:Fractures of the odontoid, prevalent among the elderly but affecting diverse demographics, pose significant risks ranging from mild discomfort to severe disability or fatality. These fractures, often stemming from trauma, are particularly frequent in the cervical spine. While commonly attributed to high-impact events like traffic accidents in adults, even low-energy incidents such as falls can precipitate these fractures in the elderly. Previous studies have explored loading conditions and treatment effects; however, a comprehensive investigation into the influence of the magnitude and direction of the force involved in the trauma, and the influence of the sex and age of the patient remains scarce so we want to delve deeper into this topic. METHODS:This study uses a finite element (FE) model to analyze the response of 3D models of the second cervical vertebra (extracted from computed tomography images) exposed to different loads of magnitude and force. 52 patients were analyzed in this study. The patients were divided into 4 groups: male <70, female <70, male >70, female >70) under different force conditions. Von Mises stress values were obtained when loads of 200 N and 1500 N were applied to the anterior surface of the odontoid with different angles of incidence in the sagittal and axial plane. RESULTS:Odontoid fractures in subjects over 70 years of age are more frequent in female, the maximum stresses produced in the odontoid are 181 MPa and are considerably higher compared to male, which is 131 MPa. In young subjects (<70 years), the differences between sex are less marked, 113 MPa for female and 114 MPa for male. CONCLUSIONS:Load direction is one of the main factors affecting odontoid fracture, especially in subjects >70 years of age; by understanding this, the mechanisms that cause different types of fractures can be understood and better strategies can be proposed to apply different treatment approaches to them, both from a medical and surgical point of view.

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.

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 [...]

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.

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.

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.

Antecedentes Las fracturas de odontoides, frecuentes entre los ancianos, pero que afectan a diversos grupos demográficos, plantean riesgos significativos que van desde una leve molestia hasta una discapacidad grave o la muerte. Estas fracturas, que a menudo se derivan de un traumatismo, son particularmente frecuentes en la columna cervical. Si bien se atribuyen comúnmente a eventos de alto impacto como accidentes de tránsito en los adultos, incluso incidentes de baja energía como caídas que pueden precipitar estas fracturas en los ancianos.Estudios previos han explorado las condiciones de carga y los efectos del tratamiento; sin embargo, una investigación exhaustiva sobre la influencia de la magnitud y la dirección de la fuerza involucrada en el traumatismo, y la influencia del sexo y la edad del paciente sigue siendo escasa, por lo que queremos profundizar en este tema. Métodos Este estudio utiliza un modelo de elementos finitos (EF) para analizar la respuesta de modelos 3D de la segunda vértebra cervical (extraídos de imágenes de tomografía computarizada) expuestas a diferentes cargas de magnitud y fuerza. Se analizaron 52 pacientes en este estudio.Los pacientes fueron divididos en 4 grupos: varones <70, mujeres <70, varones >70, mujeres >70) bajo diferentes condiciones de fuerza.Se obtuvieron valores de esfuerzo de von Mises al aplicar cargas de 200N y 15.00N a la superficie anterior del odontoides con diferentes ángulos de incidencia en el plano sagital y axial. Resultados Las fracturas de odontoides en sujetos mayores de 70 años son más frecuentes en el sexo femenino, los esfuerzos máximos producidos en el odontoides son de 181MPa y son considerablemente mayores en comparación con el masculino, que es de 131MPa. En sujetos jóvenes (<70 años), las diferencias entre sexos son menos marcadas, 113MPa para el sexo femenino y 114MPa para el masculino. Conclusiones La dirección de la carga es uno de los principales factores que afectan a la fractura de odontoides, especialmente en sujetos >70 años; Al comprender esto, se pueden entender los mecanismos que causan los diferentes tipos de fracturas y proponer mejores estrategias para aplicarles diferentes enfoques de tratamiento, tanto desde el punto de vista médico como quirúrgico.

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.

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, CO2 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.