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  • PublicaciónRestringido
    Analytic adjoint solution for incompressible potential flows
    (AIP Publishing, 2025-06-10) Lozano, Carlos; Ponsin, J.; Ponsin Roca, Jorge; Instituto Nacional de Técnica Aeroespacial (INTA)
    We obtain the analytic adjoint solution for two-dimensional incompressible potential flow for a cost function measuring aerodynamic force using the connection of the adjoint approach to Green's functions and also by establishing and exploiting its relation to the adjoint incompressible Euler equations. By comparison with the analytic solution, it is shown that the naïve approach based on solving Laplace's equation for the adjoint variables can be ill-defined. The analysis of the boundary behavior of the analytic solution is used to discuss the proper formulation of the adjoint problem as well as the mechanism for incorporating the Kutta condition in the adjoint formulation.
  • PublicaciónAcceso Abierto
    On the Characteristic Structure of the Adjoint Euler Equations and the Analytic Adjoint Solution of Supersonic Inviscid Flows
    (Multidisciplinary Digital Publishing Institute (MDPI), 2025-05-30) Lozano, Carlos; Ponsin, J.; Ponsin Roca, Jorge; Instituto Nacional de Técnica Aeroespacial (INTA)
    The characteristic structure of the two-dimensional adjoint Euler equations is examined. The behavior is similar to that of the original Euler equations, but with the information traveling in the opposite direction. The compatibility conditions obeyed by the adjoint variables along characteristic lines are derived. It is also shown that adjoint variables can have discontinuities across characteristics, and the corresponding jump conditions are obtained. It is shown how this information can be used to obtain exact predictions for the adjoint variables, particularly for supersonic flows. The approach is illustrated by the analysis of supersonic flow past a double-wedge airfoil, for which an analytic adjoint solution is obtained in the near-wall region. The solution is zero downstream of the airfoil and piecewise constant around it except across the expansion fan, where the adjoint variables change smoothly while remaining constant along each Mach wave within the fan.
  • PublicaciónRestringido
    Structural health and usage monitoring of an unmanned turbojet target drone
    (SAGE, 2018-03-22) Terroba, F.; Frövel, M.; Atienza, R.
    Aerial target drones are an important tool for the training of anti-air batteries and missiles for defense and homeland protection. These target drones are highly loaded structures that require a reliable inspection after each flight. A health and usage monitoring system based on load path changes has been developed. These changes are measured with fiber optic Bragg grating sensors which have been implemented in high loaded structural parts of the fuselage of the DIANA IA, which is operated by the Spanish National Institute for Aerospace Technology. The health and usage onitoring system has been tested and calibrated by destructive tests, introducing defined damages in fuselage stringers and evaluating the structural damage by the measured strain distribution. The tests have shown that a simple system based on four fiber optic Bragg grating sensors is able to detect barely visible structural damages in the entire high loaded front fuselage of the drone. The health and usage monitoring system requires only on-ground equipment and enables a fast turnaround of the drone after each flight. Two DIANAs have been instrumented for their application in service. First flight tests have been performed and the performance of the health and usage monitoring system has been evaluated.
  • PublicaciónAcceso Abierto
    Recubrimientos protectores para componentes de turbinas de aviación y de generación de energía depositados por proyección por plasma
    (Elservier, 2000-07-26) Agüero, A.; Álvarez Alba, J.; García de Blas, F. J.; Valles González, M. P.
    Coatings produced by aluminium diffusion, called aluminide are employed to increase the oxidation and corrosion resistance, increasing the life of Ni and Co base superalloys components at temperatures comprised between 900 and 1050ºC. Consequently these coatings are frequently employed in aeronautic and power generation turbines as well as in the chemical industry. Aluminides are industrially produced by pack cementation or CVD and recently it has been demonstrated that its resistance significantly increases when Cr is added (chrome-aluminides). During this work, a feasibility study has been carried out in order to determine if plasma spray can be employed for depositing this type of coatings on turbine blades. Therefore, aluminium and aluminium/chromium layers were deposited on Ni base IN100 superalloy specimens that were subsequently subjected to a diffusion heat treatment under Ar flow. Characterisation and analysis of the coatings were carried out by metallography , SEM and EDS. Cyclic oxidation tests were carried out at 1050º C while molten sulphate hot corrosion was performed at 900º C. The results of this preliminary study are promising and indicate that plasma spray can be developed as an industrial process for production of aluminide and chrome-aluminide coatings.

    Los recubrimientos producidos por difusión de aluminio, llamados aluminuros, se emplean para aumentar la resistencia a la oxidación y a la corrosión, incrementando la vida de componentes fabricados con superaleaciones de níquel y cobalto a temperaturas comprendidas entre 900 y 1050º C. Por ello se emplean muy frecuentemente en turbinas aeronaúticas y de producción de energía y en la industria química. Los aluminuros se obtienen industrialmente mediante cementación o CVD y recientemente se ha demostrado que su resistencia aumenta significativamente cuando se añade cromo (cromoaluminuros). Durante el presente trabajo, se ha realizado un estudio de viabilidad para determinar si la proyección por plasma puede ser utilizada para la producción de estos recubrimientos sobre álabes de turbina. Así pues, se depositaron capas de aluminio y aluminio/cromo sobre probetas de la superaleción base níquel IN100 que a continuación fueron sometidas a un tratamiento térmico de difusión bajo flujo de argón. La caracterización y análisis de los recubrimientos producidos se llevó a cabo mediante técnicas metalográficas, microscopía electrónica de barrido y espectroscopía de dispersión de energía de rayos X. Se realizaron ensayos de oxidación cíclica a 1050ºC y de corrosión por sulfatos fundidos a 900ºC. Los resultados de este estudio preliminar han sido muy satisfactorios e indican que la proyección por plasma puede ser desarrollada como procedimiento industrial para la producción de recubrimientos aluminuros y cromoaluminuros.
  • PublicaciónAcceso Abierto
    Slurry and Thermal Spray Coatings for Protection of New Generation Steam Engine Components
    (ASM International, 2001-03-14) Agüero, A.; Muelas Gamo, Raúl; Román Gárate, Alicia
  • PublicaciónRestringido
    Steam Oxidation Resistant Coatings for Steam Turbine Components: A Feasibility Study
    (Scientific.Net, 2001-10-20) Agüero, A.; García de Blas, F. J.; Muelas Gamo, Raúl; Sánchez, A.; Tsipas, Sophia A.
    The principal objective of the COST Action 522 is to raise the operating temperatures of both gas and steam turbines in order to increase their efficiency to reduce fuel consumption and emissions. Concerning steam turbines, the operating temperature is expected to rise from 550°C to 650°C, and the use of oxidation resistant coatings is being considered for the first time in Europe. In this preliminary work, two deposition techniques have so far been explored: slurry paints and atmospheric plasma spray (APS). Commercially available materials, known to have good oxidation resistance, were selected for both deposition techniques: one aluminium slurry and three alloyed materials for thermal spray: AlFe, FeCrAl and NiAl. The coatings were characterised by SEM-EDS and steam oxidation testing was carried out at 650°C. The preliminary findings show that some of the studied coatings may offer adequate protection.
  • PublicaciónRestringido
    Al Slurry Coatings for Molten Carbonate Fuel Cell Separator Plates
    (Scientific.Net, 2001-01-20) Agüero, A.; García, M. C.; Muelas Gamo, Raúl; Sánchez, A.; Pérez, Francisco J.; Duday, David; Hierro, M. P.; Gómez, Consuelo
    The corrosion behaviour of Al slurry coated AISI 310 stainless steel, with and without diffusion heat treatment, was investigated as a wet seal material for molten carbonate fuel cell (MCFC) at 650°C. The results were compared with IVD Al coated AISI 310. Characterization of the samples before and after exposure to the eutectic 62 mol% Li2CO3-38 mol% K2CO3 mixture at 650°C for 1000 h by SEM-EDS and XRD was carried out. The presence of LiAlO2 on the coated samples was confirmed by XRD. The slurry Al-coated stainless steels performed at least as well as the IVD Al coating.
  • PublicaciónRestringido
    Thermal spray coatings for molten carbonate fuel cells separator plates
    (Elsevier, 2001-10-30) Agüero, A.; García de Blas, F. J.; García, M. C.; Muelas Gamo, Raúl; Román Gárate, Alicia
    Molten salt corrosion at the wet seal of separator plates is one of the principal life-limiting factors of molten carbonate fuel cells (MCFC). The wet seal must therefore be coated with an aluminide layer that is commonly produced by ion vapor deposition (IVD) of Al followed by heat treatment. However, this coating only lasts approximately 20 000 h and not the 40 000 h expected for a cell life. Moreover, the IVD Al coating is also very expensive since only a few plates can be coated simultaneously due to size limitations of the existing commercial vacuum chambers employed in IVD. The need of heat treatment further increases costs, particularly since it requires long heating and cooling cycles in order to minimize distortion of the thin stainless steel plates. Thermally sprayed coatings constitute an alternative that requires neither containment nor heat treatment, and also provides the possibility of depositing materials more resistant to molten carbonates than plain aluminides. However, separator plates coated by thermal spray suffer distortion, due both to sand blasting (usually required prior to coating), and to the heat transfer process that occurs during the spraying process. In this work, commercially available coatings have been applied by plasma spray and high velocity oxyfuel (HVOF), employing alternative surface preparation methods. Moreover, substrate pre-heating and/or cooling during deposition were examined in order to eliminate substrate distortion. FeCrAl, and NiAl as well as a quasi-crystalline approximant alloy AlCoFeCr were deposited on AISI 310 foils, and after optimization the resulting coatings were characterized by means of scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). The optimized coatings were then tested by immersion in a 62 mol.% Li2CO3/38 mol.% K2CO3 molten carbonate eutectic mixture at 700°C and by electrochemical impedance spectroscopy. IVD Al coatings were also tested for comparison purposes. The results indicate that FeCrAl exhibits a higher molten salt corrosion resistance than IVD aluminide coatings whereas NiAl was attacked shortly after the beginning of the test. The QC approximant AlCoFeCr resisted 1000 h of attack but its composition changed. Grinding of the substrate prior to coating resulted in good adhesion and substrate distortion was minimized by Ar cooling during deposition.
  • PublicaciónRestringido
    Low temperature MOCVD process for fast aluminium deposition on metallic substrates
    (Wiley, 2005-12-19) Agüero, A.; Gutiérrez, Marcos; García Martínez, María
    A CVD pilot plant, designed and built in INTA, is presently being used to deposit aluminium coatings with applications in the fields of industrial and aeronautic turbines, as well as on the protection of components employed in the chemical industry, waste incinerators, fuel cells, and for the replacement of Cd coatings in aeronautic components. The industrial process currently used to coat aeronautic and industrial turbine components employs AlCl3 as precursor at 700–1100 °C and requires more than 12 h per batch (including loading, heating, coating and cooling) due to the relatively low deposition rates and the long heating and cooling cycles. The new process carried out at INTA employs an organometallic precursor, which results in higher deposition rates, at 280–350 °C with a total processing time lower than 5 h per batch. As in any other CVD process, this one allows deposition of coatings in complex geometry components such as on the inner surfaces of turbine blades and heat exchangers tubes. Other important advantages of this particular process are the possibility of recovering and re-utilising the unreacted precursor as well as the high purity of the produced coatings in comparison with those produced by other commercially available technologies. It is well known that the higher the contamination degree, the lower the useful life of this type of coatings. The pilot plant has a deposition chamber with a useful coating zone of 30 cm in length and 18 cm in diameter, heated by a three zone furnace equipped with a pumping system that allows working pressures of 0.1–100 mbar. The system can be manually or automatically controlled and can be easily adapted to deposit other materials. By heat treating the pure Al coatings deposited on Ni base superalloys, Ni aluminide coatings have been obtained and excellent cyclic oxidation behaviour has been observed at 1000 °C. Al has also been deposited on ferritic steels (P91 and 92) and after a suitable heat treatment Fe aluminide coatings with excellent steam oxidation resistance have been obtained. Another potential important use of this process is the deposition of dense aluminium coatings for cadmium replacement in several industrial applications.
  • PublicaciónRestringido
    New oxidation-resistant coatings for steam power plants at 650 °C
    (Wiley, 2005-12-19) Scheefer, M.; Knödler, R.; Scarlin, B.; Agüero, A.; Tsipas, D. N.
    The increase of live steam temperature and pressure in new steam power plants is certainly the most effective measure to realize the stipulated CO2 reduction targets for the conventional power industry. The development of new materials becomes a key challenge on the way forward to a more efficient and sustainable power generation.. There are two approaches being followed in materials technology in order to facilitate higher steam temperatures and pressures in the water steam cycle: 1.) The development of new materials. 2.) The use of oxidation resistant coatings on currently available materials with higher creep strength but inferior steam oxidation resistance. Both approaches are currently being followed in several R&D projects worldwide. The development and qualification of coatings is complementary to the development of new materials. The object of the EC funded R&D project SUPERCOAT is the development of new coatings according to the second approach. Eight partners from five European countries participate in the work. SUPERCOAT is the first R&D project of its kind in Europe. This presentation covers the project targets, the efforts carried out while exploring the suitability of coatings for steam turbine components and the actual state of the work. As far as possible, an excerpt from the main results of coating development and lab testing will be presented. Additionally the applied deposition techniques, chosen according to practical criteria will be presented and applicability to certain components will be discussed. Complementary, the author will report on the efforts, carried out in the German Ministry of Economic Affairs funded project “KOMET”. In this field test, empirical data are being gained from a real operating power plant and can be compared with data from the SUPERCOAT lab tests. Finally, the next steps in the project SUPERCOAT will be presented and applicability of the coatings will be evaluated.
  • PublicaciónAcceso Abierto
    Ingeniería de superficies y su impacto medioambiental
    (Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), 2007-02-28) Agüero, A.
    La ingeniería de superficies consiste en la modificación de la microestructura y/o la composición superficial de un componente mediante métodos mecánicos, físicos o químicos, que pueden implicar el aporte de otro material para cambiar las propiedades superficiales del mencionado componente. Una de sus consecuencias más importantes es que permite alargar significativamente, la vida útil de todo tipo de componentes empleados en un gran número de aplicaciones industriales. Por otra parte, contribuye al ahorro energético por permitir el aumento de las temperaturas de combustión consiguiendo una mayor eficiencia, por contribuir a la reducción de peso y por colaborar de forma significativa a disminuir la fricción entre componentes. En el presente trabajo se introduce la ingeniería de superficies, sus diferentes modalidades, algunos ejemplos de sus aplicaciones industriales y las interacciones, positivas y negativas, con el medio ambiente
  • PublicaciónRestringido
    Steam Oxidation of Slurry Aluminide Coatings on Ferritic Steels for Advanced Coal-Fired Steam Power Plants
    (Scientific.Net, 2004-08-12) Agüero, A.; Muelas Gamo, Raúl
    The use of slurry aluminide coatings on ferrite steels for advanced coal-fired steam power plants were analyzed. The materials used were found to have good high temperature oxidation resistance and deposited by techniques that can be employed to coat large steam turbine components either at the plant or at their location of manufacture. Laboratory steam oxidation testing as well as characterization of the coatings both before and after exposure was also presented. The results have provided information regarding the mechanism of protection and degradation of these coatings as well as insight for new coating development.
  • PublicaciónRestringido
    Steam Oxidation Testing of Coatings for Next Generation Steam Power Plant Components
    (Scientific.Net, 2006-08-14) Agüero, A.; Gutiérrez, Marcos; Muelas Gamo, Raúl
    To achieve higher power generation efficiency in steam turbines, operating temperatures are expected to rise from 550°C to 650°C. The use of oxidation resistant coatings on currently available materials, with high creep strength but inferior steam oxidation resistance, is being explored in order to accomplish this goal in the context of the European project “Coatings for Supercritical Steam Cycles” (SUPERCOAT). Coating techniques have been chosen on the basis of being potentially appropriate for coating steam turbine components: the application of metallic and ceramic slurries, pack cementation and the deposition of alloyed and cermet materials by thermal spray. The coatings were characterised by metallography, SEM-EDS and XRD and steam oxidation and thermal cycling laboratory testing was carried out at 650º C. In this presentation, the testing results of selected coatings will be shown including those which exhibit the most promising behaviour. For instance, slurry aluminides have been exposed to steam at 650°C for more than 38,000 h (test ongoing) without evidence of substrate attack. Some HVOF coatings such as FeAl, NiCr and FeCr also have shown excellent behaviour. The results have provided information regarding the mechanism of protection and degradation of these coatings as well as insight into new coating development.
  • PublicaciónRestringido
    Cyclic oxidation and mechanical behaviour of slurry aluminide coatings for steam turbine components
    (Elsevier, 2007-04-02) Agüero, A.; Muelas Gamo, Raúl; Gutiérrez, Marcos; Van Vulpen, R.; Osgerby, Steve; Banks, J. P.
    The excellent steam oxidation resistance of iron aluminide coatings on ferritic steels at 650 °C has been demonstrated both by laboratory tests and field exposure. These coatings are formed by the application of an Al slurry followed by diffusion heat treatment at 700 °C for 10 h. The resulting microstructure is mostly composed of Fe2Al5 on top of a much thinner FeAl layer. This coating exhibits perpendicular cracks due to thermal expansion mismatch between coating and substrate. However, these stress relieving cracks do not seem to have an effect on the mechanical properties of the substrate. Cyclic oxidation, creep resistance and TMF testing of these coatings at 650 °C indicate excellent performance.
  • PublicaciónAcceso Abierto
    Recubrimientos contra la corrosión a alta temperatura para componentes de turbinas de gas
    (Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), 2007-10-30) Agüero, A.
    Los componentes de las zonas calientes de las turbinas de gas están hechos de superaleaciones desarrolladas para soportar altas temperaturas, en condiciones en que las tensiones mecánicas son relativamente altas y en las que se requiere una alta estabilidad superficial. Sin embargo, durante la década de 1950-60, se hizo evidente que las composiciones que aumentaban la resistencia mecánica de estos materiales y aquellas que ofrecían una óptima protección contra ambientes agresivos no eran compatibles. Esto, condujo a la idea de emplear recubrimientos protectores sobre materiales con alta resistencia mecánica. En la actualidad, tanto las turbinas aeronáuticas como las de generación eléctrica funcionan a temperaturas comprendidas entre 900 y 1.400 °C, gracias al uso de estos recubrimientos, indispensables para su correcto funcionamiento. En este trabajo, se describen los principales mecanismos de degradación en estos ambientes, los distintos tipos de recubrimientos actualmente utilizados por el sector industrial, empezando por los más antiguos aluminuros de níquel o cobalto, siguiendo con las adiciones de otros metales como cromo, platino, etc., a estos últimos, para incrementar su vida útil, continuando con los recubrimientos en capa MCrAlY y terminando por las barreras térmicas. También, se describen las técnicas de deposición empleadas por la industria para depositar estos recubrimientos y se concluye con las últimas líneas de investigación en curso para optimizarlos.
  • PublicaciónRestringido
    Long exposure steam oxidation testing and mechanical properties of slurry aluminide coatings for steam turbine components
    (Elsevier, 2005-11-21) Agüero, A.; Muelas Gamo, Raúl; Pastor Muro, Ana; Osgerby, Steve
    Important efforts to develop new steels or to protect high creep strength steels in order to allow operation of steam turbines at 650 °C are being carried out world-wide to increase efficiency. Within the European Project “SUPERCOAT” (Coatings for Supercritical Steam Cycles), work has been concentrated in the development of coatings to withstand 50,000–100,000 h of operation at 650 °C under high pressure steam. Aluminide coatings on ferritic–martensitic steels produced by applying an Al slurry followed by a diffusion heat treatment, have shown to be protective at 650 °C under steam for at least 32,000 h of laboratory steam exposure under atmospheric pressure. Although the “as diffused” coatings present through thickness cracks, these do not propagate during exposure to steam or thermal cycling and no new cracks seem to develop. Moreover, no changes in residual stresses could be observed after thermal cycling. Microstructural characterization of samples at different periods of exposures has been carried out by SEM-EDS and XRD. The principal mechanism of coating degradation is loss of Al at the surface due to inwards diffusion. Microhardness as well as Young's modulus and fracture strength were measured using well established techniques. The coatings show reasonable ductility (∼1.6%) when stressed in tension between room temperature and 400 °C which further increases at higher temperatures providing evidence that the coatings should withstand the mechanical conditions likely to be encountered in service.
  • PublicaciónRestringido
    Hot corrosion study of coated separator plates of molten carbonate fuel cells by slurry aluminides
    (Elsevier, 2002-12-02) Pérez Trujillo, Francisco Javier; Duday, David; Hierro, María Pilar; Gómez de Castro, Consuelo; Agüero, A.; García, M. C.; Muelas Gamo, Raúl; Sánchez Pascual, A.; Martínez, L.
    The corrosion behavior of Al coated AISI 310S stainless steel by slurry and ion vapor deposition (IVD) was investigated as an electrolyte seal material in a mounted carbonate fuel cell (MCFC) at 650 °C. The results were compared with uncoated AISI 310S stainless steel and TA6V alloy. The characterization of the samples after exposure to the eutectic 62 mol.% Li2CO3–38 mol.% K2CO3 mixture at 650 °C up to 1000 h has shown the presence of LiAlO2 (coated samples), LiFeO2 and LiCrO2 (stainless steels), and Li2TiO3 (TA6V) oxides at the scale–melt interface. The electrochemical impedance spectroscopy (EIS) technique has shown high values of polarization resistances for TA6V and lower values for coated steels. The uncoated AISI 310S stainless steel have shown the lowest polarization resistance. A mechanism for the corrosion of Al-coated stainless steels in molten carbonate is proposed taking into account thermodynamic simulations, X-ray diffraction (XRD), scanning electron microscopy (SEM) characterizations, and EIS results. This proposed mechanism confirms that a slurry aluminide coating is able to improve the stainless steel behavior in molten carbonate. However, the TA6V titanium alloy is the most resistant material in molten carbonate but the Al-coated stainless steels appear as the best lifetime-cost compromise.
  • PublicaciónRestringido
    Vacuum tribological behaviour of self-lubricating quasicrystalline composite coatings
    (Wiley, 2006-03-09) García de Blas, F. J.; Román, A.; De Miguel, C.; Longo, Federico; Muelas Gamo, Raúl; Agüero, A.
    High-temperature-resistant self-lubricating coatings are needed in space vehicles for components that operate at high temperatures and/or under vacuum. Thick composite lubricant coatings containing quasicrystalline alloys as the hard phase for wear resistance can be deposited by a thermal spray technique. The coatings also contain lubricating materials (silver and BaF2CaF2 eutectic) and NiCr as the tough component. This paper describes the vacuum tribological properties of TH103, a coating of this type, with a very good microstructural quality. The coating was deposited by high-velocity oxygen fuel spraying and tested under vacuum using a pin-on-disc tribometer. Different loads, linear speeds, and pin materials were studied. The pin scars and disc wear tracks were characterised using a combination of scanning electron microscopy and energy dispersive spectrometry. A minimum mean steady friction coefficient of 0.32 was obtained when employing an X750 Ni superalloy pin in vacuum conditions under 10 N load and 15 cm/s linear speed, showing moderate wear of the disc and low wear of the pin.
  • PublicaciónRestringido
    Silicon Surface Nanostructuring for Covalent Immobilization of Biomolecules
    (ACS Publications, 2008-06-03) Rogero, Celia; Chaffey, Benjamin T.; Mateo Martí, Eva; Sobrado, J. M.; Horrocks, Benjamin R.; Houlton, Andrew; Lakey, Jeremy H.; Briones, C.; Martín Gago, J. A.; Instituto Nacional de Técnica Aeroespacial (INTA); Ministerio de Ciencia e Innovación (MICINN)
    We present a straightforward strategy to control the average distance of immobilized biomolecules on silicon surfaces. We exploit the reaction taking place between the amino residues within the biomolecules (lysine groups of proteins or the N-terminus of oligomers of peptide nucleic acid, PNA) and the aldehyde-terminated groups presented in a mixed aldehyde/alkyl organic monolayer on a silicon surface. The mixed monolayers were prepared by a thermal reaction of hydrogen-terminated Si(111) with a mixture of undecene and undecenyl-aldehyde. We quantitatively evaluate the surface concentration of aldehyde in the monolayer by atomic force microscopy and an intensity analysis of core level X-ray photoemission spectroscopy peaks. These complementary techniques show that the surface density of the reactive terminal groups reflects the mole fraction of aldehyde in the reactive solution used to modify the silicon surface. The further immobilization of proteins or peptide nucleic acids on the monolayer shows that the density of biomolecules reproduces the aldehyde surface density, which indicates a specific covalent attachment and a negligible nonspecific adsorption. The proposed procedure makes possible to control the average distance of the immobilized active biomolecules on the silicon surface, which could be of great relevance for applications in the interdisciplinary field of biosensors.
  • PublicaciónRestringido
    A chamber for studying planetary environments and its applications to astrobiology
    (IOP Science Publishing, 2006-07-13) Mateo Martí, Eva; Prieto Ballesteros, O.; Sobrado, J. M.; Gómez Elvira, J.; Martín Gago, J. A.; Instituto Nacional de Técnica Aeroespacial (INTA); Comunidad de Madrid
    We have built a versatile environmental simulation chamber capable of reproducing atmospheric compositions and surface temperatures for most of the planetary objects. It has been especially developed to make feasible in situ irradiation and characterization of the sample under study. The total pressure in the chamber can range from 5 to 5 × 10−9 mbar. The required atmospheric composition is regulated via a residual gas analyser with ca ppm precision. Temperatures can be set from 4 K to 325 K. The sample under study can be irradiated with ion and electron sources, a deuterium ultraviolet (UV) lamp and a noble-gas discharge UV lamp. One of the main technological challenges of this device is to provide the user the possibility of performing ion and electron irradiation at a total pressure of 0.5 mbar. This is attained by means of an efficient differential pumping system. The in situ analysis techniques implemented are UV spectroscopy and infrared spectroscopy (IR). This machine is especially suitable for following the chemical changes induced in a particular sample by irradiation in a controlled environment. Therefore, it can be used in different disciplines such as planetary geology, astrobiology, environmental chemistry, materials science and for instrumentation testing.