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Aged muscles accumulate satellite cells with a striking decline response to damage. Although intrinsic defects in satellite cells themselves are the major contributors to aging-associated stem cell dysfunction, increasing evidence suggests that changes in the muscle-stem cell local microenvironment also contribute to aging. Here, we demonstrate that loss of the matrix metalloproteinase-10 (MMP-10) in young mice alters the composition of the muscle extracellular matrix (ECM), and specifically disrupts the extracellular matrix of the satellite cell niche. This situation causes premature features of aging in the satellite cells, contributing to their functional decline and a predisposition to enter senescence under proliferative pressure. Similarly, reduction of MMP-10 levels in young satellite cells from wild type animals induces a senescence response, while addition of the protease delays this program. Significantly, the effect of MMP-10 on satellite cell aging can be extended to another context of muscle wasting, muscular dystrophy. Systemic treatment of mdx dystrophic mice with MMP-10 prevents the muscle deterioration phenotype and reduces cellular damage in the satellite cells, which are normally under replicative pressure. Most importantly, MMP-10 conserves its protective effect in the satellite cell-derived myoblasts isolated from a Duchenne muscular dystrophy patient by decreasing the accumulation of damaged DNA. Hence, MMP-10 provides a previously unrecognized therapeutic opportunity to delay satellite cell aging and overcome satellite cell dysfunction in dystrophic muscles.

The primary austenitic solidification mode of Twinning Induced Plasticity (TWIP) steel weld joints is one of the most important issues limiting its weldability. In order to gain knowledge on this topic, a comprehensive study was carried out through numerical simulation of diffusive-convective phenomena of fluid flow and heat transfer of the melted material in the weld pool of TWIP steel weld joints. Weldments were performed using different heat inputs and constraint conditions. The predictions of convective motion, thermal history and cooling rates estimated by finite element (FE) and finite volume (FV) simulations were correlated with chemical species segregation (Mn, C, Al and Si) and the solidification mode in the fusion zone. The microstructural characterization of weld joints and the numerical results provided a full analysis of the weld pool solidification process. Results revealed a relationship between both the dendrite size and Mn segregation with the estimated velocity field of liquid material in the melted zone. Moreover, the presence of d-ferrite was experimentally detected in some weld joints and associated with the convective movement of melted material and chemical segregation. The cellular dendritic growth mode found in some weld joints contributed to the formation of d-ferrite and promoted the transition of the solidification mode from austenitic to ferritic-austenitic. As well d-ferrite allowed to mitigate hot-cracking and interrupted the Mn-enriched liquid film migration towards the heat-affected zone, avoiding the formation of liquation cracks. The presence of d-ferrite phase maintained a high mechanical strength providing improved elongation regarding the welded material mechanical properties., Peer Reviewed, Postprint (author's final draft)

Mentre que en els últims anys s'ha avançat molt en la distribució de tecnologies d'impressió 3D com FDM, poc s’ha avançat en solucions de baix cost per utilitzar metalls mitjançant la fabricació additiva. L'objectiu d'aquest projecte és presentar una solució que utilitzi una impressora FDM modificada, així com un equip mínim d'alta gamma, per poder fabricar peces de superaliatge amb base de níquel: Inconel 718 Aquest treball ésla continuació de projectes anteriorsrealitzats en la mateixa unitat del departament. L'objectiu principal era fabricar mostres de tracció amb una mida més gran per a treballar amb mostres similars als componentsimpresos en 3D de la vida real que es poden trobar a la indústria. A més,s’han incorporat una sèrie de millores en el procés de impressió que permeten treballar amb mostres més grans i amb més fiabilitat. S’han imprimit mostres per assatjos de tracció de fins a 80 mm de llargada i amb un gruix de 8 mm, sense mostrar defectes amb una inspecció visual. Els aglutinants es van eliminar amb un primer debinding de l’agluitinantsoluble a 50‐60ºC durant 20 h i un posterior debinding tèrmic a 600ºC durant una hora. Finalment es va fer un sinteritzat a temperatures entre 1295‐1310°C amb uns temps de 4-6h No es van podertrobarmillores en les propietatsmecàniquesja que es va trobar que lesmostrestenien defectes importants a l’interior. La causa més probable d’aquest defectes podria estar al procés de debinding on no es va eliminar de manera efectiva tot l’aglutinant, que va afectar al sinteritzat de les mostres. S’han provat una àmplia gamma de suportsi configuracions per garantir el màxim rendiment durant la sinterització, de manera que s’ha trobat un compromís per limitar la deformació a l’eix longitudinal o torcejat i mantenir una bona qualitat del sinteritzat. Això s’ha fet afegint un pes a la part superior de les mostres durant la sinterització, així com posant les mostres en un suport. Aquest suport assegura el màxim de conducció directa de, Mientras que en los últimos añosse ha avanzado mucho en la distribución de tecnologías de impresión 3D como la FDM, apenasse ha avanzado en soluciones de bajo coste para utilizar el metal mediante la fabricación aditiva. El objetivo de este proyecto es presentar una solución que utilice una impresora FDM modificada, así como un equipomínimo de alta gama, para poderfabricar piezas de superaleación con base de níquel: Inconel 718 Este trabajo es la continuación de proyectos anteriores llevados a cabo en la misma unidad del departamento. El principal objetivo era fabricar muestras de tracción de mayor tamaño para probar muestras más cercanas a los componentes impresos en 3D de la vida real que se encuentran en la industria. Además,se han incorporado una serie de mejoras en el proceso de impresión que permiten trabajar con muestras más grandes y con más fiabilidad. Se han impreso muestras para ensayos de tracción de hasta 80 mm de longitud y con un grosor de 8 mm, sin defectos tras una inspección visual. Los aglutinantes se eliminaron con un primer debinding del aglutinante soluble a 50‐60°C durante 20 horas, luego se realizó un debinding térmico a 600°C durante una hora. Finalmente se sinterizaron a 1295‐1310°C durante 4‐6 horas. No se obtuvieron mejoras en las propiedades mecánicas finales, ya que las muestras presentaban grandes defectos en toda su sección interior. Es probable que la causa de los defectossea un incorrecto proceso de debinding, donde no se eliminó de manera efectiva todo el aglutinante, que afectó al correcto sinterizado de las muestras. Se han probado una amplia gama de soportes y configuraciones para asegurar el máximo rendimiento durante la sinterización, de manera que se ha encontrado un compromiso para limitar el alabeo mientrasse mantiene la calidad de la sinterización. Esto se ha realizado añadiendo un peso en la parte superior de las muestras durante su sinterización, así como poniéndolas en un soporte. Este soporte asegura el máximo de condu, While a lot of progress has been on the distribution of 3D printing technologies such as FDM in the recent years, little to no advancements have been made on low‐cost solutions for using metal via additive manufacturing. The aim of this project is to present a solution using a modified FDM printer as well as a minimum of high‐end equipment to be able to manufacture parts made of nickel‐based superalloy: Inconel 718 This work is the continuation of previous projects carried out on the same department. The main goal was to manufacture tensile samples of a larger scale to test samples closer in size to a real‐life 3D printed components found in the industry. Also, a set of improvements were made on the workflow of the printing itself to allow for longer prints and easiness of use. Samplesfor tensile tests aslarge as 80mm in length and 8 mm in thickness were printed with no visible defects after a macroscopic inspection. The samples were solvent debinded at 50‐60°C for 20h, then thermal debinded at 600°C for an hour and then sintered at 1295‐1310°C for 4‐6h. No improvements were made on the final mechanical properties as the samples suffered from heavy defects across their section. An improper debinding is likely to be the cause of the defects due to left‐ over binder during the sintering. A wide array of supports and setup was tested to ensure the maximum performance during the sintering. A compromise has been found to limit the warping while improving the quality of the sintering in general by adding a weight on top of the samples during their sintering as well as putting them on a support. The support ensuresthe maximum of direct heat conduction between the support and the tube of the furnace. Hardnesstesting, tensile testing with videoextensiomerty and micrography/fractography were carried out on the samples. A good repeatability was achieved with the new printing parameters, allowing the printing of large parts in a constant fashion. While lower than in previous wo, Incoming

In this study the production of 3D-printed pieces made from Inconel 718 using Metal Extrusion Additive Manufacturing of highly-filled polymers has been investigated. The printer used was a Prusa I3 MK3 printer modified with a gravity fed-pellets screw extruder. The feedstock was pellets composed of metal powder and polymeric binders. Different types of geometries and sizes were printed during the study with the aim to determine both the limits of the technique and the final mechanical properties of the pieces after the whole process (Fig 1). After printing, debinding, and sintering some of the samples were cut and observed by SEM to determine the presence of remaining porosity inside the pieces. The samples for tensile tests were subjected to a final precipitation heat-treatment to check the mechanical properties. As a general conclusion of the study, better results were obtained in small pieces with a small thickness. As thickness increases porosity and the amount of large defects created during the printing or debinding steps rises. On the other hand, pieces with regular geometries show less warping. This warping comes from the large shrinkage experimented by the samples during sintering. The hardness and yield strength of the tensile samples are within the expected range for this material, but ductility is easily affected by the presence of defects.