18 research outputs found

    New insights into the use and circulation of reindeer antler in northern Iberia during the Magdalenian (ca. 21-13 cal ka BP)

    Get PDF
    Interactions between prehistoric foragers and reindeer at the end of the Pleistocene are still poorly documented in northern Iberia, particularly the reasons and means by which their antlers were collected, processed and circulated. Here we review the main osseous industries dated to between 21 and 13 cal ka BP, focusing on the use and circulation of reindeer antler as a raw material for the production of weapons and tools by Magdalenian foragers. Thirty-six reindeer antler artefacts were identified from 11 Iberian sites that are located at either end of the Pyrenees: the Cantabrian region to the west, and to a lesser extent, in Catalonia to the east. Despite biases in the identification of production objectives (end-products), a detailed techno-typological, chronological and geographical analysis of these assemblages reveals both the existence of a consistent reindeer antler industry in northern Iberia and long-distance connections between the Cantabrian region and the Pyrenees. The integration of contemporary macrofaunal data makes it possible to explore the extension of the reindeer?s ecological niche in northern Iberia, as well as strategies for the acquisition and circulation of reindeer antler in the peninsula. Assuming that some reindeer assemblages result from the import of raw materials to supply manufacturing activities, we propose a scenario where the acquisition of reindeer antlers may have been organised at a local scale in the Basque region, and potentially in the neighbouring territories of Navarre, Cantabria and Asturias. On the other hand, in Catalonia, the combination of both faunal and technological data supports the hypothesis that reindeer antlers were imported (along with pelts) over longer distances, probably from the northern Pyrenees.This research was primarily financed by an international collaboration between the Spanish Ministry of Science and Innovation (MCIN/AEI/10.13039/501100011033) and the European Union (NextGenerationEU/PRTR) as part of the HumAntler project (PCI2021-122053-2 B) based at the Grupo I + D + i EvoAdapta (UC). Funding was also provided by the UMR-5608 TRACES laboratory of the University of Toulouse and PID2020-114462 GB-I00 of the Spanish Ministry of Science and Innovation (University of Salamanca)

    Nanocomposites of silver nanoparticles embedded in glass nanofibres obtained by laser spinning

    Get PDF
    Nanocomposites made of non-woven glass fibres with diameters ranging from tens of nanometers up to several micrometers, containing silver nanoparticles, were successfully fabricated by the laser spinning technique. Pellets of a soda-lime silicate glass containing silver nanoparticles with varying concentrations (5 and 10 wt%) were used as a precursor. The process followed to obtain the silver nanofibres did not agglomerate significantly the metallic nanoparticles, and the average particle size is still lower than 50 nm. This is the first time that glass nanofibres containing silver nanoparticles have been obtained following a process different from electrospinning of a sol–gel, thus avoiding the limitations of this method and opening a new route to composite nanomaterials. Antibacterial efficiency of the nanosilver glass fibres, tested against one of the most common Gram negative bacteria, was greater than 99.99% compared to the glass fibres free of silver. The silver nanoparticles are well-dispersed not only on the surface but are also embedded into the uniform nanofibres, which leads to a long lasting durable antimicrobial effect. All these novel characteristics will potentially open up a whole new range of applications.Xunta de Galicia | Ref. 10DPI303014PRMinisterio de Ciencia e Innovación | Ref. MAT2009-14542-C02-0

    Depuración de efluentes contaminados por hidrocarburos aromáticos policíclicos mediante carbones activados: evaluación del proceso de adsorción

    Get PDF
    Tesis doctoral presentada en el Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica de la Universidad de Oviedo. 2009. Tutor de la tesis: José Rubén García Menéndez[EN] Polycyclic aromatic hydrocarbons (PAH) constitute an important class of highly toxic environmental pollutants. As a consequence of their low biodegradability, adsorption on activated carbon is nowadays one of the most attractive techniques for the removal of PAH from wastewater. Despite having been the subject of plentiful studies in the literature, investigation of the rate and mechanisms of the adsorption process itself and the role of the characteristics of the adsorbent are still ambiguous and remain unclear. In this work, the performance of carbon adsorbents as a media for polycyclic aromatic hydrocarbons removal has been studied. To attain this goal, an exhaustive analysis of the chemical and textural characteristics of the selected activated carbon was carried out, in order to throw some light on the forces involved in the adsorption process. Moreover, the role of the functionalities of activated carbons on the adsorption was explored by evaluating adsorbents with similar porosity and different surface chemistry. The results confirmed that adsorption depended strongly on the pore-size distribution of the adsorbent, with micropores being the active sites for adsorption. However, the adsorption behaviour should not be exclusively linked to the porosity of the carbons, functionalization of the carbon surface strongly influenced the overall adsorption capacity of carbons. Adsorbents with a higher non-polar character have to be more efficient for PAH adsorption. This behaviour has been linked to the presence of dispersive interactions between the basal planes and the polyaromatic structure of the hydrocarbon. The interaction of the organic compound with the carbon sites is highly dependent on the solvent affinity for these active sites, as the competitive adsorption of the solvent becomes important. However, one must also take into account the dimensions of the molecules, and therefore the accessibility to the porosity of the adsorbents.[ES] Los hidrocarburos aromáticos policíclicos (HAP) constituyen un grupo de compuestos que presentan una amplia distribución en el medio ambiente, y que han sido catalogados como sustancias peligrosas por sus propiedades cancerígenas y mutagénicas. Debido a su baja biodegradabilidad, una de las técnicas más eficaces para su eliminación en fase acuosa es la adsorción en materiales de elevada área superficial, tales como los carbones activados. Si bien el tratamiento de aguas residuales con elevada carga contaminante constituye una de las principales áreas de expansión en la utilización de carbones activados, aún se desconocen muchos aspectos en procesos de adsorción de moléculas complejas -tales como los HAP- , relacionados con las propiedades de estos adsorbentes y su capacidad de eliminación de contaminantes. Esta información podría ser de gran utilidad para posteriores aplicaciones de estos materiales en procesos de depuración de aguas residuales. En el presente trabajo se ha evaluado la eficacia de los métodos de adsorción sobre carbones activados para la eliminación de HAP presentes en agua. Para tal fin, se ha realizado un análisis exhaustivo de las características, tanto químicas como texturales, de los carbones activados antes y después de la adsorción de estos compuestos, con vistas a elucidar los distintos factores que se ven implicados en el proceso de adsorción. Asimismo, se han realizado diversos tratamientos de oxidación con diferentes agentes oxidantes, con objeto de investigar el papel de los grupos funcionales de los carbones. Los resultados experimentales han puesto de manifiesto que en el proceso de adsorción de HAP, tanto las características del adsorbato, como del adsorbente son de gran importancia; las capacidades de adsorción no sólo dependen de las características texturales de los carbones activados sino también de sus propiedades químicas. Tanto la afinidad del contaminante orgánico por el medio en el que se encuentra disuelto, como el posible efecto competitivo del disolvente por los centros activos de adsorción, y la accesibilidad de los componentes de la disolución a la porosidad del carbón activado, son factores clave para entender el proceso global de adsorción.Peer reviewe

    On the Adsorption Kinetics and Equilibrium of Polyaromatic Hydrocarbons from Aqueous Solution

    Get PDF
    The purpose of the present work was to explore the removal of three polycyclic aromatic hydrocarbons (naphthalene, fluorene and acenaphtene) (PAHs) from aqueous solution onto an activated carbon. The adsorption performance of these compounds (both kinetic and equilibrium) has been discussed in terms of their chemical and physical properties. The results showed that the rate of adsorption was strongly dependent on the molecular size of the hydrocarbons. Thus, for example, steric hindrances associated with acenaphthene inhibited the accessibility of this compound to the high-energy sites. Under equilibrium conditions, the uptake seemed to be governed by the carbon-PAH affinity, as the lowest uptake was obtained for naphthalene which displayed the fastest adsorption rate. The interactions between the studied pollutants and the activated carbon seemed to be controlled by two factors, viz. aromaticity and water solubility. As a general rule, the higher the number of aromatic rings in the polycyclic hydrocarbon, the more favoured the adsorbate—carbon interactions. Analysis of the carbon after adsorption of the studied hydrocarbons indicated that the accessibility restrictions to the porosity of the carbon can also lead to weaker interactions with the activated carbon.The authors acknowledge the financial support of the Spanish MICINN (CTM2008-01956) and CSIC (200980I131). M.H. thanks CSIC for her JAE-Doc research contract.Peer reviewe

    Procedimiento para la inhibición del crecimiento microbiano

    No full text
    [EN] The invention relates to a method for inhibiting microbial growth using glass with a composition containing various oxides of elements such as calcium, zinc, silicon and boron. The invention also relates to the use of the method for producing containers, drugs, medical devices, surgical implants, fabrics, transportation means, air systems and water systems.[ES] El objeto de la presente invención se refiere a un método para la inhibición del crecimiento microbiano en el cual se utiliza un vidrio con una composición en la cual se incluyen diversos óxidos de elementos tales como calcio, cinc, silicio y boro. La invención hace referencia igualmente al uso de dicho procedimiento en la fabricación de envases, fármacos, dispositivos médicos, implantes quirúrgicos, tejidos, medios de transporte, instalaciones de aire o instalaciones de agua.Peer reviewedConsejo Superior de investigaciones CientíficasA1 Solicitud de adición a la patent

    Method for inhibiting microbial growth

    No full text
    El objeto de la presente invención se refiere a un método para la inhibición del crecimiento microbiano en el cual se utiliza un vidrio con una composición en la cual se incluyen diversos óxidos de elementos tales como calcio, cinc, silicio y boro. La invención hace referencia igualmente al uso de dicho procedimiento en la fabricación de envases, fármacos, dispositivos médicos, implantes quirúrgicos, tejidos, medios de transporte, instalaciones de aire o instalaciones de agua.Peer reviewedConsejo Superior de Investigaciones Científicas (España)B1 Patente sin examen previ

    Kinetics of naphthalene adsorption on an activated carbon: Comparison between aqueous and organic media

    Get PDF
    The purpose of this work was to explore the kinetics of naphthalene adsorption on an activated carbon from aqueous and organic solutions. Kinetic curves were fitted to different theoretical models, and the results have been discussed in terms of the nature and properties of the solvents, the affinity of naphthalene to the solutions, and the accessibility to the porosity of the activated carbon. Data was fitted to the pseudo-second order kinetic model with good correlation coefficients for all the solution media. The faster adsorption rate was obtained for the most hydrophobic solvent (heptane). The overall adsorption rate of naphthalene seems to be controlled simultaneously by external (boundary layer) followed by intraparticle diffusion in the porosity of the activated carbon when water, ethanol and cyclohexane are used as solvents. In the case of heptane, only two stages were observed (pore diffusion and equilibrium) suggesting that the limiting stage is the intraparticle diffusion. The low value of the boundary thickness supports this observation.The authors thank the support of the Spanish MICINN (CTM2008-01956). COA thanks her Ramon y Cajal research contract.Peer reviewe

    Improved phenol adsorption on carbons after mild temperature steam reactivation

    Get PDF
    The purpose of this work is to explore steam reactivation at moderate temperatures of activated carbon exhausted with phenol, a highly toxic compound frequently present in industrial wastewater. The spent carbon was treated with steam at various temperatures (450, 600 and 850 °C) and times (from 5 to 60 min). Promising results were obtained by applying moderate temperatures and times. Whereas at low temperatures the complete regeneration of the carbon is not accomplished, an almost quantitative desorption of the pollutant was achieved at 600 °C after exposure times below 30 min, with minimal damages in the porous network of the carbon. Further reutilization of the regenerated carbon resulted in a superior performance towards phenol uptake. The regeneration efficiency at 850 °C strongly depends on the time of reactivation, with an enhanced phenol uptake when short treatment times are applied. Prolonged duration of the regeneration treatment reduced phenol adsorption capacities, due to overreactivation of the carbon in the steam atmosphere, and to the blockage of the porous carbon network.The authors thank the Bulgarian Academy of Sciences and the Division of International Affaires of CSIC for financial support (grant 2007BG0015). COA thanks the Spanish MICINN for a Ramon y Cajal research contract and the financial support (project CTM2008-01956). BC thanks CSIC for a Marina Bueno fellowship (EST001047)Peer reviewe

    Importance of the Hydrophobic Character of Activated Carbons on the Removal of Naphthalene from the Aqueous Phase

    No full text
    13 pages.A commercial activated carbon was systematically modified by heat treatment at 450°C and 850°C to obtain a series of carbons with various oxygen contents, porous structures and surface functionalities. The carbons were used to investigate the role of adsorbent properties on the removal of naphthalene from aqueous solution. The results confirmed that the adsorption of naphthalene depended strongly on the pore-size distribution of the adsorbent. DTG analysis of the exhausted samples indicated that adsorption forces were stronger in carbons with pores of dimensions close to those of naphthalene. Functionalization of the carbon also influenced its overall adsorption capacity, with uptake being favoured in carbons of a basic nature. The hydrophilic character of the carbons gave rise to strong water competition due to increasing polarity in the adsorbents. This polarity created hydration clusters that reduced the accessibility and affinity of naphthalene molecules to the inner pore structure.Peer reviewe
    corecore