Whiskers of Al2O3 as reinforcement of a powder metallurgical 6061 aluminium matrix composite

An Al–Mg–Si alloy matrixcomposite reinforced with 10 vol.% of alumina whiskers (Al2O3w) has been processed by powder metallurgy and investigated. The Al2O3w were produced as single crystal c-axis alpha-alumina fibres at pre-pilot scale via vapour–liquid–solid (VLS) deposition in a cold-wall air-tight furnace with alumina linings. As far as we know, this is the first report of the utilization of whiskers of Al2O3 as reinforcing elements for Al alloys. Tensile tests have been performed on the composite at room and high temperatures. Results show that the AA6061 alloy reinforced with the as-produced Al2O3whiskers has remarkably high mechanical properties at room temperature. This is attributed to the high quality of the Al2O3 single crystals and to the strong bonding attained between them and the 6061 alloy matrixFinancial support of Spanish MEC, project MAT2006-01251, and regional government, Xunta de Galicia, PGIDT05TMT23902CTPeer reviewe

A contribution to the study of the stability of clay minerals from the soil solution composition at different pF values

(EN)The composition of the soil solution of various horizons of Galician soils was studied to gain insight into the direction of the processes of weathering and neoformation by means of stability diagrams of the clay minerals. The soil solution was extracted by compression at various pF values. The most significant results are as follows: In all the cases studied the mineral in equilibrium with the soil solution is a 1:1 phyllosilicate. As the pF at which the soil solution is extracted increases, corresponding to smaller pore size, pH increases and silica concentration falls. The stable mineral does not vary significantly between different horizons of the same profile. Each parent material gives rise to a different zonation in the stability diagrams. The predictions of the stability diagrams are in general agreement with the mineralogical data of the clays of the horizons in question. Finally, weathering processes in Galicia are briefly commented on.(ES)Se realiza un estudio de la composición de la solución del suelo extraída por compresión a diferentes valores de pF como medio de conocer la dirección de los procesos de alteración y neoformación en diversos horizontes de suelos de Galicia, utilizando diagramas de estabilidad de los minerales de la arcilla. Los resultados más significativos son los siguientes: En todos los casos estudiados el mineral en equilibrio con la solución del suelo es un filosilicato 1:1. La solución extraída a valores crecientes de pF, que corresponden a tamaños de poros más pequeños, presenta valores de pH más altos y disminución de la concentración de sílice. No se aprecian diferencias significativas en cuanto al mineral estable en los diferentes horizontes de un mismo perfil. Para cada material original se aprecia una diferente zonaci6n en los diagramas de estabilidad. Las predicciones de los diagramas de estabilidad están generalmente de acuerdo con los datos mineralógicos de las arcillas de los horizontes correspondientes. Finalmente se realizan unas breves consideraciones sobre los procesos de alteración en Galicia

Study of the sintering process of zeolites ZSM-5 with other bioceramic compounds. Conformation through the freeze casting process for bone tissue regeneration samples

Las zeolitas son aluminosilicatos ampliamente utilizados a nivel científico e industrial por la gran superficie específica que estos compuestos cerámicos presentan. Esta característica permite que puedan ser utilizadas como partículas alojadoras de otros compuestos y que, por lo tanto, podrían ser usadas como biomaterial con la posible propiedad de ser un liberador sostenido de medicamentos u otros compuestos que ayuden a la regeneración de tejidos, con su consecuente posible aplicación en el campo de la regeneración del tejido óseo. Sin embargo, como cualquier otro compuesto cerámico, las zeolitas necesitan ser sometidas a un proceso de sinterización que las conforme como un cuerpo sólido. Dicho proceso provoca cambios en su estructura interna y, en concreto, también varía su superficie específica. Para poder conformar este material como una pieza sólida y, al mismo tiempo, mantener su propiedad de alojador de otras moléculas en su interior, en este estudio se propone su mezcla con otros compuestos biocerámicos con propiedades de regeneración del tejido óseo como son el vidrio bioactivo 1393 (BG 1393) y el fosfato bicálcico, conformado por un 60% de hidroxiapatito y un 40% de beta fosfato tricálcico (60%/40% HA/-TCP)Zeolites are aluminosilicates widely known at a scientific and industrial level because of the great specific surface area they present. Thus, zeolites can be used to storage inside of them different compounds. In this way, zeolites could be a sustained deliver biomaterial of drugs or other molecules that could promote the tissue regeneration as, for example, bone tissue. Although, as any other ceramic compound, zeolites need to be sintered to be conformed as a solid material. This thermal process provokes changes in their inner structure and also modifies their specific surface area. In order to be able to conform this material as a solid sample and, at the same time, keep its high values of specific surface area, this study proposes to mix zeolites with other bioceramic compounds that also present bone tissue regeneration properties as bioactive glass 1393 (BG 1393) and biphasic calcium phosphates, formed by 60% of hydroxyapatite and 40% of beta tricalcium phosphate (60%/40% HA/-TCP)El presente trabajo se ha llevado a cabo con la financiación de la Fundación Pedro Barrié de la MazaS

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

El género Isoetes L. en Galicia: clave para la identificación de especies según la ornamentación y tamaño de las macrósporas

El trabajo realizado por los autores en estos últimos años en relación al estudio del género Isoetes L. ha puesto de manifiesto la presencia de dos nuevas especies mediterráneas en territorio gallego. Así, el catálogo actual del género en Galicia está constituido por 6 especies, entre las cuales se encuentran algunas catalogadas como raras en su área de distribución natural, como Isoetes durieui o bien amenazadas como el endémico Isoetes fluitans, de reciente descripción. La presencia de estas interesantes plantas, nos ha motivado a desarrollar una clave con apoyo gráfico que facilite su identificación. Para cada una de las especies, se aportan además otros datos de interés corológico, ecológico y fenológico

Una nueva planta parásita del género Lathraea L. (Scrophulariaceae) para el catálogo gallego

Durante una de las fases del trabajo de campo que estamos realizando sobre el estudio de la estructura, composición florística y conservación del bosque de ribera a lo largo del río Navia (Lugo), hemos recolectado entre otras, una especie de la familia de las escrofulariáceas que identificamos como Lathraea squamaria L. La especie, que no había sido citada de Galicia hasta la fecha (Planellas, 1852; Meri no, 1905-1909; Niño Ricoi et. al., 1994; Romero, 2008), tampoco se conoce del vecino Portugal (Sam pai o, 1946; Pereira Coutinho, 1974; Amaral Franco, 1984)

Histological response of soda-lime glass-ceramic bactericidal rods implanted in the jaws of beagle dogs

Bacterial and fungal infections remain a major clinical challenge. Implant infections very often require complicated revision procedures that are troublesome to patients and costly to the healthcare system. Innovative approaches to tackle infections are urgently needed. We investigated the histological response of novel free P2O5 glass-ceramic rods implanted in the jaws of beagle dogs. Due to the particular percolated morphology of this glass-ceramic, the dissolution of the rods in the animal body environment and the immature bone formation during the fourth months of implantation maintained the integrity of the glass-ceramic rod. No clinical signs of inflammation took place in any of the beagle dogs during the four months of implantation. This new glass-ceramic biomaterial with inherent bactericidal and fungicidal properties can be considered as an appealing candidate for bone tissue engineeringThis work was supported by the Spanish Ministry of Science and Innovation (MICINN) under the projects MAT2012-38645. A.P. Tomsia work was supported by the National Institutes of Health/National Institute of Dental and Craniofacial Research (NIH/NIDCR) Grant No. 1R01DE015633S

Towards the Use of Yellow Clay in Fired Bricks

This chapter deals with the study of the possibility of using yellow clay - which was only used in pottery so far- in the civil engineering field as building materials, especially in the field of fired bricks. With the aim to improve the technological properties of yellow clay based bricks, two wastes were used as secondary raw materials. The first one is a mineral waste - pyrrhotite ash - this waste was neither characterized nor valued before by any other author. While the second waste is an organic waste - cedar sawdust - which is from the artisanal sector. Clay bricks containing yellow clay and different content of wastes were prepared and tested to evaluate their technological properties: water absorption, bulk density, porosity and mechanical strength… The test results indicate that the addition of wastes to clay bricks improves their technological properties and highlights the possibility of wastes reuse in a safe and sustainable way

Aprovechamiento de residuos líticos provenientes de aguas subterráneas carbonatadas.

Póster en Día Mundial del Agua. Debates y charlas para la ciudadanía, del 22 de febrero al 22 de marzo. Organiza: Consejo Insular de Aguas de Tenerife, 2019

Art, environment, sustainability. Use of lithic waste from carbonated groundwater

Se han localizado, analizado y aplicado creativamente residuos minerales que depositan las aguas subterráneas, sobresaturadas en CO2, extraídas mediante galerías/minas. El análisis documental abarca el archipiélago canario; la recogida de muestras y el desarrollo experimental se ha realizado principalmente en galerías y conducciones de Tenerife. Las rocas-residuo de mayor resistencia han demostrado ser magníficos materiales para esculturas labradas en formato medio. Los restos fragmentados y las rocas de menor consistencia, tipo toba, pueden encontrar utilidad en fabricación de cales-morteros compatibles con la restauración de obras patrimoniales. Debido a la capacidad petrificadora de estas aguas, se abren múltiples posibilidades en creación tridimensional mediante moldes y/o madreformas, tanto en escultura (obra única) como en actividades artesanales que requieren repetición sucesiva de elementos de similares características. La recopilación exhaustiva de datos y los análisis efectuados evidencian la necesidad de una investigación básica multidisciplinar que ofrezca, en relación con el tratamiento de las aguas subterráneas y las salmueras de rechazo, alternativas de reutilización compatibles con la sostenibilidad medioambiental.Mineral residues deposited in groundwater have been identified, analyzed and creatively applied. These residues are oversaturated in CO2 and are extracted by means of galleries/ mines. The documentary analysis covers the Canary Archipelago; the collection of samples and experimental development has been carried out mainly in galleries and conducts in Tenerife. The most resistant waste-rocks have proved to be magnificent materials for medium format sculpture. The fragmented remains and the rocks of lesser consistency, such as tufa, can be useful in the manufacture of lime-mortars compatible with the restoration of heritage works. Due to the petrifying capacity of these waters, multiple possibilities are opened in three-dimensional creation by means of molds and/or mother forms, both in sculpture (unique work) and in artisan activities that require successive repetition of elements of similar characteristics. The exhaustive collection of data and the analyses carried out show the need for basic multidisciplinary research that offers, in relation to the treatment of groundwater and reject brine, alternatives for reuse that are compatible with environmental sustainability