Diagramas de equilibrio cuaternarios ZrO2-Al2O3-SiO2-(CaO, MgO, TiO2). Una poderosa herramienta para el desarrollo de nuevos materiales por sinterización reactiva

En este articulo se exponen, discuten y evalúan los trabajos que sobre materiales de Mullita-Circona obtenidos por sinterización reactiva dirigió e inspiro Salvador de Aza sobre la base de los diagramas de equilibrio de fase multicomponentes ZrO2-Al2O3-SiO2-(CaO, MgO, TiO2). Se analiza su impacto en distintas áreas de la ciencia y tecnología cerámicas tales como chamotas refractarias, industria del aluminio, etc. También se proponen posibles campos de aplicación futura como es el caso de prótesis dentales sustituyendo a los materiales de circona parcialmente estabilizada con tierras raras.Peer reviewe

Synthesis and Antimicrobial Activity of a Silver-Hydroxyapatite Nanocomposite

A silver-hydroxyapatite nanocomposite has been obtained by a colloidal chemical route and subsequent reduction process in H2/Ar atmosphere at C. This material has been characterized by TEM, XRD, and UV-Visible spectroscopy, showing the silver nanoparticles (65 nm) supported onto the HA particles (130 nm) surface without a high degree of agglomeration. The bactericidal effect against common Gram-positive and Gram-negative bacteria has been also investigated. The results indicated a high antimicrobial activity for Staphylococcus aureus, Pneumococcus and Escherichia coli, so this material can be a promising antimicrobial biomaterial for implant and reconstructive surgery applications.This work was supported by Bioker Research S.L. and by the Spanish Ministry of Education and Science under Project CENIT-INTELIMPLANT (ref.: 20071210). M. Díaz has been supported by Spanish Ministry of Education and Science and CSIC under I3P Program financed by European Social FundS

Portland cement clinkers turned into garnets by spark plasma sintering

The feasibility of sintering Portland cement clinker powders by Spark Plasma Sintering (SPS) has been studied. Different SPSed compacts have been successfully obtained by this technique. The compacts have been characterized by means of X-Ray Diffraction, InfraRed spectroscopy, Scanning Electron Microscopy, Raman Microscopy and Vickers hardness. It is worth noting the finding that slight mineralogical variations in the starting compositions may induce dramatic changes, both in the final mineralogical composition and in the morphology, which can affect the properties of the SPSed compacts. Thus, we find that SPS allows artificial garnets to be obtained in the laboratory by applying pressures as low as 50 MPa, while they are materials that would require much higher pressures in natural environments (2-10 GPa). According to the Selsing model, it has been calculated that the material itself acts as a pressure amplifier at the micrometric level by a factor of 40-200 times. A new model describing the formation of garnets considering the emergence of two transitory eutectic liquids has been explained to justify this phenomenon. This result opens the door to looking for compositions for specific applications with high added value in the field (i.e. high hardness), mainly in the manufacturing of high-pressure (GPa) phases by applying relatively low pressures (MPa).The Authors acknowledge the financial support of the PID2020-119130 GB-I00 project funded by MCIN/AEI/10.13039/501100011033 and by CSIC under grant 201960E103. Thanks to the Official Laboratory for Testing of Construction Materials (LOEMCO, Getafe, Madrid, Spain) for free supply of the clinker sample

Inhibitory effect on in vitro Streptococcus oralis biofilm of a soda-lime glass containing silver nanoparticles coating on titanium alloy

This is an open-access article.-- et al.This paper reports the effect of soda-lime-glass-nAg coating on the viability of an in vitro biofilm of Streptococcus oralis. Three strains (ATCC 35037 and two clinical isolates from periodontitis patients) were grown on coated with glass, glass containing silver nanoparticles, and uncoated titanium alloy disks. Two different methods were used to quantify biofilm formation abilities: crystal violet staining and determination of viable counts. The influence of the surface morphology on the cell attachment was studied. The surface morphology was characterized by scanning electron microscopy (SEM) and using a profilometer. SEM was also used to study the formation and the development of biofilm on the coated and uncoated disks. At least a >99.7% inocula reduction of biofilm respect to titanium disks and also to glass coated disks was observed in the glass-nAg coated disks for all the studied strains. A quantitative evaluation of the release of silver was conducted in vitro to test whether and to what extend the biocidal agent (silver) could leach from the coating. These findings suggest that the biofilm formation of S. oralis strains is highly inhibited by the glass-nAg and may be useful for materials which require durable antibacterial effect on their surfaces, as it is the case of dental implants. © 2012 Cabal et al.This work was supported by the Spanish Ministry of Science and Innovation under the project MAT2009-14542-C02-01.Peer Reviewe

Nanotechnology in joint replacement

El pdf del artículo es la versión post-print.This paper reviews the most relevant achievements and new developments in the field of nanomaterials and their possible impact on the fabrication of a new generation of reliable and longer lasting implants for joint replacement. Special emphasis is given to the role of nanocomposites with different microstructural designs: micro-nano composites, nano-nano composites, macro-micro-nano composites as well as bioinspired hierarchical composite materials. These nanostructured materials have opened up an exciting avenue in the design of non-metallic biocompatible, crack growth resistant, tough, and mechanically resistant implants with a lifespan close to the life expectancy of the patients. Copyright (c) 2009 John Wiley & Sons, Inc.Authors would like to acknowledge the European Commission for its financial support under contract IP Nanoker, Contract number NMP3-CT-2005-515784.Peer Reviewe