Mechanical properties of Al2O3 inverse opals by means of nanoindentation

In order to understand the mechanical behaviour of Al2O3 inverse opals, nanoindentation techniques have been implemented in material layers with three different microstructures, in terms of hollow or polystyrene spheres, with Al2O3 shells of distinct wall thickness. Different indenter tip geometries as well as contact loading conditions have been used, in order to induce different stress field and fracture events to the layers. Field emission scanning electron microscopy and focused ion beam have been employed to understand accommodation of plastic deformation induced during the indentation process. Results show that materials with polystyrene spheres exhibit higher hardness and modulus under sharp indentation, and cracking resistance under spherical indentation. Furthermore, deformation is discerned to be mainly governed by the rotation of the microspheres. In the case of the inverse opals made of hollow spheres, the main deformation mechanisms activated under indentation are the rearrangement and densification of themPostprint (author's final draft

Influence of the Test Configuration and Temperature on the Mechanical Behaviour of WC-Co

In this work, the effect of the test configuration and temperature on the mechanical behaviour of cemented carbides (WC-Co) with different carbide grain sizes (dWC) and cobalt volume fractions (VCo), implying different binder mean free paths ( Co), was studied. The mechanical strength was measured at 600º C with bar-shaped specimens subjected to uniaxial four-point bending (4PB) tests and with disc specimens subjected to biaxial ball-on-three-balls (B3B) tests. The results were analysed within the frame of theWeibull theory and compared with strength measurements performed at room temperature under the same loading conditions. A mechanical degradation greater than 30% was observed when the samples were tested at 600ºC due to oxidation phenomena, but higherWeibull moduli were obtained as a result of narrower defect size distributions. A fractographic analysis was conducted with broken specimens from each test configuration. The number of fragments (Nf) and the macroscopic fracture surface were related to the flexural strength and fracture toughness of WC-Co. For a given number of fragments, higher mechanical strength values were always obtained for WC-Co grades with higher KIc. The observed differences were discussed based on a linear elastic fracture mechanics (LEFM) model, taking into account the effect of the temperature and microstructure of the cemented carbides on the mechanical strength.Junta de Andalucía P12-TEP-262

Quality of bladder cancer information on YouTube.

Introduction YouTube is one of the social networks most widely used as a source of information. However, there are doubts about the scientific quality of the information available. This study aims to characterise this by analysing videos about bladder cancer posted on YouTube. Material and methods This was a cross-sectional descriptive study of the first 50 Spanish-language videos published on YouTube, leaving 38 for analysis. The videos were evaluated by three urologists using two validated questionnaires: Patient Education Materials Assessment Tool (PEMAT) and DISCERN (quality criteria for consumer health information), classifying them according to the score of the latter, in poor quality (1–2 points) and moderate/good quality (3–5 points). Results The median PEMAT score was 71.6% (16–5–100%) for understanding and 35.5% (0–100%) for action. According to DISCERN, 26 videos (66.7%) were of poor quality and 12 (30.8%) of moderate/good quality. We found significant differences in terms of PEMAT of understanding (p = 0.004) and action (p = 0.000). In total, 90.9% of those involving medical staff were of low quality, which is paradoxical, but statistically significant (p = 0.01). Furthermore, 52.4% of those describing relevant information were of moderate/good quality, and 94.1% of those not describing relevant information were of poor quality (p = 0.02). Conclusions More than 60% of the videos published on YouTube about bladder cancer in Spanish are of low quality. This represents an important risk of misinformation for the general public to whom most of them are addressed.post-print729 K

Diseño, fabricación y ensayo de materiales laminados basados en el metal duro con propiedades mecánicas mejoradas

Los metales duros (WC-Co) y cermets son materiales muy usados como materiales de herramientas. Sin embargo, los WC-Co presentan pérdidas de propiedades mecánicas a temperaturas elevadas, mientras que la fragilidad elevada de los segundos compromete su empleo en este tipo de aplicaciones. El uso de materiales con función gradiente y laminados se plantean como una potencial solución. En este trabajo se fabrican distintos tipos de diseños de laminados (WC-Co/WC-Co y Cermet/WC-Co), que permiten alcanzar los equilibrios de comportamiento tribomecánico y termo-mecánico deseados. En este contexto, se realiza la caracterización macroestructural (homogeneidad e integridad estructural de las capas) y microestructural (composición química, análisis de fases, fenómenos de difusión en las intercaras). La caracterización mecánica incluye la resistencia a flexión y la tenacidad de fractura, así como la resistencia al rayado. Los resultados se discuten en el marco de la mecánica de la fractura elástica lineal, los mecanismos de aumento de tenacidad (desvío y bifurcación de las grietas) y la presencia de un umbral de resistencia mecánica asociado a la distribución de tensiones de compresión y tracción en los laminados diseñados y fabricados en este trabajo.Junta de Andalucía P12-TEP-262

Improved adhesion of cathodic arc PVD AlCrSiN coating on ion-implanted WC-Co substrates

Ion implantation has been shown to improve adhesion strength of AlCrSiN coatings due to a synergic enhancement on fracture toughness and load bearing capability of the substrate that can potentially increase the in-service efficiency of coated cutting tools. In this work, AlCrSiN coatings deposited by PVD on WC-Co substrates implanted with Ti, Cr and N ion species have been processed. The mechanical properties and adhesion have been characterized by contact techniques and the residual stress of the coatings and substrates have been evaluated using FIB-DIC technique and Vickers indentation tests, respectively. An improvement of adhesion strength is obtained for treated substrates, especially for those implanted with titanium and chromium ions. This improvement is attributed to the introduction of residual stresses in the substrate, which increases its fracture toughness and enhances its load bearing capability.Work funded through The Spanish Ministry of Science, Innovation and Universities through grants PGC-2018-096855-B-C41, PGC-2018-096855-B-C42 and PGC-2018-096855-A-C4

Field Effectiveness of Drones to Identify Potential Aedes aegypti Breeding Sites in Household Environments from Tapachula, a Dengue-Endemic City in Southern Mexico

Aedes aegypti control programs require more sensitive tools in order to survey domestic and peridomestic larval habitats for dengue and other arbovirus prevention areas. As a consequence of the COVID-19 pandemic, field technicians have faced a new occupational hazard during their work activities in dengue surveillance and control. Safer strategies to monitor larval populations, in addition to minimum householder contact, are undoubtedly urgently needed. Drones can be part of the solution in urban and rural areas that are dengue-endemic. Throughout this study, the proportion of larvae breeding sites found in the roofs and backyards of houses were assessed using drone images. Concurrently, the traditional ground field technician’s surveillance was utilized to sample the same house groups. The results were analyzed in order to compare the effectiveness of both field surveillance approaches. Aerial images of 216 houses from El Vergel village in Tapachula, Chiapas, Mexico, at a height of 30 m, were obtained using a drone. Each household was sampled indoors and outdoors by vector control personnel targeting all the containers that potentially served as Aedes aegypti breeding sites. The main results were that the drone could find 1 container per 2.8 found by ground surveillance; however, containers that were inaccessible by technicians in roofs and backyards, such as plastic buckets and tubs, disposable plastic containers and flowerpots were more often detected by drones than traditional ground surveillance. This new technological approach would undoubtedly improve the surveillance of Aedes aegypti in household environments, and better vector control activities would therefore be achieved in dengue-endemic countries

Gobiernos municipales: por un desarrollo local basado en la gobernanza democrática

El presente reporte da cuenta del proceso de intervención universitaria en el municipio de Tlajomulco de Zúñiga, Jalisco, México, a través del PAP “Gobiernos Municipales: por un desarrollo local basado en la gobernanza democrática”, cuyo propósito general es: Contribuir a la promoción de la cultura de paz, la economía social y solidaria y la promoción de los DDHH en Tlajomulco, desde la Dirección General de Cultura de Paz y Gobernanza, a través de analizar, conocer, difundir documentar y evaluar situaciones relacionadas con la construcción de espacios de paz basados en la economía social y solidaria y la difusión de los DDHH, en la construcción de una ciudad en paz y segura, que, desde una perspectiva interdisciplinar, da continuidad a los proyectos emprendidos durante el periodo anterior, referidos al rescate y apropiación social de los espacios públicos desde la perspectiva de la paz positiva, impulso a las iniciativas de emprendimiento y formación en finanzas para los jóvenes del municipio. En el periodo de primavera 2022, se tuvieron los siguientes objetivos: • Elaborar el diseño de un espacio público, como respuesta a una demanda de los vecinos del fraccionamiento Sendero Real, a través de las mesas de paz, que implementa el gobierno municipal de Tlajomulco de Zúñiga. • Responder a la demanda de apoyo del sector juvenil de Tlajomulco y El Salto, expresada en los talleres de diagnóstico promovidos por el Instituto de la Juventud Tlajomulquense y del Instituto de la Juventud del Salto. • Diseñar y aplicar una evaluación de los programas públicos de mesas de paz y chamba para todos. La metodología aplicada implico la intervención de estudiantes de diferentes disciplinas a partir de grupos sociales específicos que presentan demandas de atención para la recuperación de sus espacios públicos y por tanto requieren de acompañamiento para el diseño de estos, el impulso al emprendimiento través de la realización de Podcast dirigidos a los jóvenes, la integración y aplicación de una propuesta de evaluación de los programas públicos “mesas de paz” y “”chamba para todos”.ITESO, A.C