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Materials such as wood, textiles, or plastics that are part of the exhibition system in museums are known to emit pollutants such as organic acids. Scientific and technical objects that include these materials in their composition can themselves be a potential source of emissions, which, together with inappropriate humidity and temperature conditions, can lead to corrosion of the metallic parts. In this work, we have studied the corrosivity of different locations in two venues of the Spanish National Museum of Science and Technology (MUNCYT). Coupons of the most representative metals from the collection were placed in different showcases and rooms for 9 months. The corrosion of the coupons has been evaluated in terms of the rate of mass gain, colour changes and characterisation of the corrosion products. The results were correlated to the relative humidity and concentration of gaseous pollutants to determine which metals are most susceptible to corrosion. The results show that metal artefacts exposed in showcases have a higher risk of corrosion than those exposed directly in the room, and that some pollutants are emitted by the artefacts. The corrosivity of the museum environment is low for copper, brass, and aluminium in most locations; however, some placements present a higher aggressivity for steel and lead, due to the high humidity and the presence of organic acids.

Summary of the scientific communication presented in the 11th Iberian Conference on Tribology IBERTRIB2022, held during 6 - 8 October 2022 in Setúbal, Portugal, Improvements regarding durable lubrication together with minimized wear are mandatory for obtaining long-term, functioning metallic joint prostheses. For this goal, CoCr surface was functionalized with Graphene Oxide (GO), characterized by FTIR and XPS, and tested at tribocorrosion. Deposition of graphene oxide was carried out by consecutive steps: alkalinization of CoCr; intermediate coupling via 3-aminopropyltriethoxysilane (APTES) which was cured at 45 °C for 24 h; and final assemble of GO layers at 60 °C for 24 h upon exposure with silane-coated CoCr. FTIR displayed C=C band confirming the assembly of GO on silane-coated CoCr surfaces. XPS elucidated reaction between primary amines of APTES and epoxy groups of GO, free -OH groups in APTES and carboxyl groups in GO, and reaction between APTES primary amines and -OH from carboxyl groups of GO. COF values for GO incubated on silane-coated CoCr disks show stationary values near 0.2. CoCr surfaces in as-reception state show higher COF values increasing at longer testing times.

The antiferromagnetic (AFM) transition of the normal ZnFe2O4 has been intensively investigated with results showing a lack of long-range order, spin frustrations, and a “hidden” entropy in the calorimetric properties for inversion degrees δ ≈ 0 or δ = 0. As δ drastically impacts the magnetic properties, it is logical to question how a δ value slightly different from zero can affect the magnetic properties. In this work, (Zn1-δFeδ)[ZnδFe2-δ]O4 with δ = 0.05 and δ = 0.27 have been investigated with calorimetry at different applied fields. It is shown that a δ value as small as 0.05 may affect 40% of the unit cells, which become locally ferrimagnetic (FiM) and coexists with AFM and spin disordered regions. The spin disorder disappears under an applied field of 1 T. Mossbauer spectroscopy confirms the presence of a volume fraction with a low hyperfine field that can be ascribed to these spin disordered regions. The volume fractions of the three magnetic phases estimated from entropy and hyperfine measurements are roughly coincident and correspond to approximately 1/3 for each of them. The “hidden” entropy is the zero point entropy different from 0. Consequently, the so-called “hidden” entropy can be ascribed to the frustrations of the spins at the interphase between the AFM-FiM phases due to having δ ≈ 0 instead of ideal δ = 0. Sitio web de la revista (Consulta: 03-05-2022)

Obra ressenyada: Maximiliano BARRIO GOZALO, Esclavos y cautivos: Conflicto entre la cristiandad y el islam en el siglo XVIII. Valladolid: Servicio de Publicaciones de la Junta de Castilla y León, 2006.

Obra ressenyada: Maximiliano BARRIO GOZALO, Esclavos y cautivos: Conflicto entre la cristiandad y el islam en el siglo XVIII. Valladolid: Servicio de Publicaciones de la Junta de Castilla y León, 2006.

Los materiales de base cemento están siendo utilizados cada vez más como matrices confinantes en la inertización de residuos, tanto peligrosos como radiactivos. En su utilización en este ámbito, uno de los principales problemas es el de la degradación a largo plazo, cuya caracterización mediante técnicas tradicionales se hace inviable, por lo que se hace necesario el desarrollo de métodos acelerados, como el basado en la aplicación de campos eléctricos. En este artículo, se presenta un resumen de algunos de los trabajos de los autores en este campo: Monitorización in-situ del tratamiento eléctrico por difracción de neutrones; cuantificación de las fases cristalinas antes y después de un tratamiento acelerado mediante análisis Rietveld de los espectros de difracción de Rayos X con radiación Sincrotrón y por último comparación de los resultados obtenidos por el método acelerado, mediante integración de los perfiles absolutos obtenidos por EDX, con un método estandarizado de lixiviación.

69th Annual Meeting of the International Society of Electrochemistry, The organic electrolyte derived from Et4NBF4 is often used in commercial supercapacitors and research studies. This work deals with three organic electrolytes with the same anion BF4- but different cation, Et4N+, Pr4N+ and Bu4N+ in combination with two binder-free carbon monoliths, one microporous and another mesoporous. The decomposition voltage and the minimum/maximum working voltage are measured with reference to a quasi-reference gold electrode. From these results the stability voltage window and the working voltage window are determined for each electrolyte (Table 1). The stability voltage window broadens according to the trend Bu4NBF4>Pr4NBF4>Et4NBF4 for the two monoliths. The working voltage window coincides with the stability voltage window for the mesoporous monolith and follows that trend. However, the working voltage window differs from the stability voltage window for the microporous monolith and follows the trend Et4NBF4>Pr4NBF4>Bu4NBF4. It is explained by the presence of a sieving or saturation effect associated with the cations Pr4N+ and Bu4N+. The specific capacitances associated with the cations and anions are separately measured (Table 1). The specific capacitances follow the trend BF4->Et4N+>Pr4N+>Bu4N+ for the two monoliths. The values are higher for the microporous carbon with larger specific surface area. For the mesoporous monolith the surface areas due to pores with sizes larger than certain values are estimated. From comparison of the ratios of the specific capacitances of the cations and anion on the one hand and the ratios of the surface areas due to pores with sizes larger than certain values on the other, the minimum size of pore able to host the cations and anion as they are electro-adsorbed at the double layer is deduced. This size results to be 0.58 nm for BF4-, 0.65 nm for Et4N+, 0.75 nm for Pr4N+ and 0.9 nm for Bu4N+. The surface areas accessible to the ions BF4-, Et4N+, Pr4N+ and Bu4N+ are estimated. The capacitance normalized by the accessible surface area is 0.078±0.003 Fm-2 for the four ions. From the point of view of the energy density (Table 1) the better electrolyte/electrode combinations are: (i) Et4NBF4 with the microporous monolith and (ii) Pr4NBF4 and Bu4NBF4 with the mesoporous monolith.

Trabajo presentado en el VIII Congreso Internacional de Materiales, celebrado en Arequipa (Perú), del 21 al 23 de noviembre de 2018

The Annual Congress of the European Federation of Corrosion, In this work, electrochemically reduced Graphene oxide (ErGO) films are formed on the biomedical grade CoCr alloy to study its possible application in biomedical field. Biocompatibility tests were carried out to assess the biomedical performance of ErGO on the CoCr alloy. The discrepancy of in vivo results found in the literature regarding the side effects of graphene led to perform a previous in vivo study with Graphene. The reduction of an aqueous suspension of graphene oxide was carried out by electrochemical methods to generate ErGO films on CoCr alloys. The direct electrodeposition process was performed by cyclic voltammetry (CV) at room temperature. Characterization of the ErGO on CoCr alloys was carried out by XPS. Electrochemical procedure led to the deposition of graphene-based films on the CoCr surfaces after the partial removal of the oxygenated functional groups present in the graphene network of starting graphene oxide (GO). Biocompatibility tests of ErGO on CoCr were evaluated in J774A.1 mouse macrophages cultures, which are the main cells involved in the primary response to foreign bodies playing a decisive role in the inflammatory reactions. In vivo tests were carried out by intraperitoneal inoculation of graphene nano particles in rats evaluating possible changes in the blood line and in different organs. CV revealed the reduction of the GO around -1,2 V. The XPS high-resolution C and O peaks mainly showed sp2 bonding and the presence of C=O and C-O residual groups covering the CoCr surface. Biocompatibility studies on mouse macrophages J774A.1 cell cultures measured by the ratio between lactate dehydrogenase and mitochondrial activities showed an enhancement in the biocompatibility on the CoCr with the ErGO films, a result that seems to become more evident as exposition time increased. Optical and SE images and vimentin expression (protein responsible for architecture of cytoplasm) after 48 h exposure in macrophage culture revealed a different cell distribution, morphology and vimentin expression on CoCr or ErGO on CoCr. Macrophages on the ErGO on CoCr surfaces were well-distributed, conserved the characteristic cell shape and vimentin expression was unaffected, results that show an improvement on the CoCr biocompatibility due to the of ErGO films on material surface. Conventional optical microscopy of in vivo experiments revealed that at 15 and 30 days after inoculation there were no visible histological alterations in liver, kidney, spleen or lung, but traces of particles were found in the peritoneal cavity. The blood analysis showed alterations indicative of the hepatic inflammatory process at both 15 and 30 days. Haematological changes were found at 30 days that consisted of alterations of the red series in the form of microcytosis with a higher concentration of mean haemoglobin as well as an alteration in coagulation due to a longer prothrombin and thromboplastin time.

This work analyses the corrosion mechanisms of carbon steel when exposed to marine atmospheres with very different chloride ion deposition rates. Two extreme situations are described, characterized by a >consolidated rust layer> (at relatively low atmospheric salinities), formed by a diffusion-controlled corrosion mechanism in which the reduction of dissolved oxygen in the aqueous film deposited on the metal is the predominant cathodic reaction, and an >exfoliated rust layer> (at high atmospheric salinities), where the cathodic reaction of hydrogen evolution becomes important, notably accelerating the corrosion process. The research has employed a range of near-surface and bulk sensitive analytical techniques (SEM/EDS, μXRD, and SEM/μRaman) to characterize the corrosion products and rust layers formed., The authors gratefully acknowledge the financial support for this study from the Ministry of Science and Innovation of Spain (CICYT-MAT2008-06649). They would also like to thank the Spanish Meteorology Agency (AEMET) for the data provided on meteorological parameters in the study area.

Trabajo presentado en el European Graphene Forum, celebrado en París (Francia), del 1 al 3 de junio de 2016

Libro de Actas del Congreso: Estudio y Conservación del Patrimonio Cultural. Celebrado del 16-19 de noviembre 2015, Málaga, La sulfuración es el mecanismo de alteración más habitual de la plata expuesta al medio atmosférico y se produce principalmente por su reacción con los compuestos sulfurados de la polución (Reacciones 1 y 2)i . Como resultado, se forman depósitos de Ag2S en la superficie de la plata que inducen una modificación del color del objeto, que tiende hacia tonos marrones y negros, así como una pérdida del brillo característico de la plata. Las reacciones involucradas son: 2Ag + H2S + ½ O2 → Ag2S + H2O (1) 2Ag + OCS → Ag2S + CO (2) Los métodos de limpieza más aplicados en restauración son mecánicos, químicos y electroquímicosii. En los últimos años, la limpieza basada en luz láser se ha comenzado a aplicar en objetos arqueológicos e históricos para la eliminación de capas de corrosión e incrustaciones. Muchos trabajos han sido encaminados al estudio del efecto que la radiación láser, con diferentes longitudes de onda y con distinta duración de pulso, induce sobre las capas de corrosión y el material subyacenteiii. Sin embargo, no se ha tenido en cuenta el efecto acumulativo de la limpieza láser. En este trabajo se ha evaluado el efecto de la limpieza con láser de nanosegundos a distintas longitudes de onda en plata pura y esterlina sulfurada y se han determinado las condiciones óptimas para la eliminación de la capa de sulfuración de manera controlada y con el mínimo daño sobre el sustrato de plata. Se ha estudiado también el efecto de la limpieza láser a corto y largo plazo., Este trabajo ha sido parcialmente financiado por el proyecto CREMEL Ref. HAR2011-22402 y el programa GEOMATERIALES 2-CM Ref. S2013/MIT-2914, así como la beca predoctoral FPI BES-2012-052716 concedida por el Ministerio de Economía y Competitividad. Finalmente, los autores agradecen el apoyo profesional de la Red de Ciencia y Tecnología para la Conservación del Patrimonio Cultural (TechnoHeritage).

Resumen del trabajo presentado a la "VII Reunión de la Sociedad Española de Técnicas Neutrónicas" celebrada en Pamplona del22 al 25 de junio de 2014., Neutron diffraction has been successfully applied to solve different problems related to construction materials, mainly profiting the possibility of studying the bulk of materials using quite big specimens, the difference in scattering between light and deuterated water and in situ monitoring the experiments, making it possible the establishment of the kinetics of the processes. In this work, in-situ monitoring of the electroosmotic flux, during realkalisation, by neutron diffraction is reported. This was achieved by designing the experimental set-up in a way to take profit of the incoherent scattering of the H of the water. Two series of cement pastes, cast with CEM I and CEM I substituted in a 35% by fly ash, previously carbonated at 100% CO2, were submitted to realkalisation treatments followed on line by simultaneous acquisition of neutron diffraction data. The analysis of soluble carbonates in the specimen, after the experiments, has confirmed the electroosmotic flux as the driving force of the realkalisation treatment. Additionally, it has been confirmed that as a consequence of the treatment, there is precipitation of portlandite on the rebar and on the zone close to the negative electrode as far as the pH is high enough. The provision of Ca2+ ions comes mainly from the dissolution of calcite. So, it has been assessed the possibility to restore the alkaline reserve by passing enough amount of charge during the realkalisation treatment.

Trabajo presentado en el NANOCEM Workshop on leaching of construction materials: minimising the environmental impact of new cementitious materials, celebrado en Barcelon (España), el 2 de mayo de 2011

Trabajo presentado en la International RILEM TC-211-PAE Final Conference, celebrada en Tulouse (Francia), del 3 al 5 de junio de 2009

Los materiales de base cemento están siendo utilizados cada vez más como matrices confinantes en la inertización de residuos, tanto peligrosos como radiactivos. En su utilización en este ámbito, uno de los principales problemas es el de la degradación a largo plazo, cuya caracterización mediante técnicas tradicionales se hace inviable, por lo que se hace necesario el desarrollo de métodos acelerados, como el basado en la aplicación de campos eléctricos. En este artículo, se presenta un resumen de algunos de los trabajos de los autores en este campo: Monitorización in-situ del tratamiento eléctrico por difracción de neutrones; cuantificación de las fases cristalinas antes y después de un tratamiento acelerado mediante análisis Rietveld de los espectros de difracción de Rayos X con radiación Sincrotrón y por último comparación de los resultados obtenidos por el método acelerado, mediante integración de los perfiles absolutos obtenidos por EDX, con un método estandarizado de lixiviación.

Trabajo presentado en la 8th International Conference on Neutron Scattering (ICNS-2005), celebrada en Sidney (Australia), del 27 de noviembre al 2 de diciembre de 2005

El comportamiento medioambiental de los cementos cuando son usados como materiales de la construcción, es de gran interés debido al aumento del uso de combustibles y materias primas alternativas en el proceso de fabricación del clinker. Los combustibles alternativos utilizados en los procesos de fabricación del cemento, pueden contener elementos no habituales en los combustibles tradicionales; por tanto, es necesario realizar un estudio del comportamiento frente a la lixiviación de los cementos obtenidos en dichos procesos, para evaluar la calidad medioambiental del producto final y garantizar su uso en la construcción. En este trabajo, el objetivo ha sido el estudio del comportamiento frente a la lixiviación de metales pesados y otros elementos, en cementos fabricados con combustibles tradicionales y cementos fabricados con combustibles alternativos

Trabajo presentado en la 3rd European Conference on Neutron Scattering (ECNS 2003), celebrada en Montpellier (Francia) del 2 al 6 de septiembre de 2003

La correcta identificación de los materiales que conforman los bienes muebles del patrimonio científico-técnico y de las interacciones entre los mismos es necesaria para establecer estrategias de conservación eficaces con criterios de intervención adaptados. En este trabajo se presenta un estudio del estado de conservación, materiales y patologías de la colección de extintores del Museo Nacional de Ciencia y Tecnología. Se ha realizado una base de datos con 56 extintores, documentando cada pieza, tipología y estado de conservación. Los análisis realizados en varias de ellas (por fluorescencia de rayos X y difracción de rayos X) han permitido identificar los materiales de los extintores, en algunos casos del contenido de los mismos, y establecer causas de degradación. En el caso de los extintores de espuma y de agua, se ha mostrado que el agente extintor es altamente corrosivo y ha causado daños severos a la pieza. En estos casos, resulta aconsejable eliminar el contenido si se quiere asegurar una correcta conservación de los extintores., A Antonio Sanz, jefe técnico del grupo SPV Sistemas. Al Ministerio de Ciencia, Innovación y Universidades-Agencia Estatal de Investigación por la financiación del proyecto COMPACT (HAR2017-89911-R) y a la Comunidad de Madrid y Fondos Estructurales y de Inversión Europeos por la financiación del proyecto TOP-HERITAGE CM (S2018/NMT_4372). A la Plataforma Temática Interdisciplinar “Patrimonio Abierto: Investigación y Sociedad” (PTI-PAIS) del CSIC por el apoyo profesional.