Tesi per compendi de publicacions. La consulta íntegra de la tesi, inclosos els articles no comunicats públicament per drets d’autor, es pot realitzar prèvia petició a l’Arxiu de la UPC / This thesis deals with the numerical simulation of welding processes. The analysis is focused either at global level, considering the full component to be jointed, or locally, studying more in detail the heat affected zone (HAZ). Even if most of the considerations are quite general, two specific welding technologies are studied in depth: multi-pass arc welding and its extension to Shaped Metal Deposition (SMD) processes (global level analysis) and Friction Stir Welding (FSW) technology (local framework). The analysis at global (structural component) level is performed defining the problem in the Lagrangian setting while, at local level, both Eulerian and Arbitrary Lagrangian Eulerian (ALE) frameworks are used. More specially, to model the FSW process, an apropos kinematic framework which makes use of an efficient combination of Lagrangian (pin), Eulerian (metal sheet) and ALE (stirring zone) descriptions for the different computational sub-domains is introduced for the numerical modeling. As a result, the analysis can deal with complex (non-cylindrical) pin-shapes and the extremely large deformation of the material at the HAZ without requiring any remeshing or remapping tools. A fully coupled thermo-mechanical framework is proposed for the computational modeling of the welding processes proposed both at local and global level. A staggered algorithm based on an isothermal fractional step method is introduced. To account for the isochoric behavior of the material when the temperature range is close to the melting point or due to the predominant deviatoric deformations induced by the visco-plastic response, a mixed finite element technology is introduced. The Variational Multi Scale (VMS) method is used to circumvent the LBB stability condition allowing the use of linear/linear P1/P1 interpolations for displacement (or velocity, ALE/Eulerian formulation) and pressure fields, respectively. The same stabilization strategy is adopted to tackle the instabilities of the temperature field, inherent characteristic of convective dominated problems (thermal analysis in ALE/Eulerian kinematic framework). At global level, the material behavior is characterized by a thermo-elasto-viscoplastic constitutive model. The analysis at local level is characterized by a rigid thermo-visco-plastic constitutive model. Different thermally coupled (non-Newtonian) fluid-like models as Norton-Ho¿ or Sheppard-Wright, among others are tested. The balance of energy equation is solved in its enthalpy format for a treatment of the phase-change phenomena. An accurate definition of the heat source (laser, arc, electron beam, etc), as well as the heat generation induced by the visco-plastic dissipation or the frictional contact (Coulomb and Norton model) are described. An ad-hoc technique to account for the use of a filler material in the shape metal deposition (SMD) process is developed. The element activation methodology proposed allows for an accurate layer-by-layer deposition of the material without introducing spurious stress/strain fields. To better understand the material flow pattern in the stirring zone, a (Lagrangian based) particle tracing is carried out while post-processing FSW results. The final numerical tool developed to study the FSW process is able to give detailed information concerning the characteristics of the weld and their relationship with the welding process parameters (e.g. advancing and rotation velocities). The simulation tool presented in this work is validated with analytical results and calibrated with experimental data. This thesis is a collection of research articles supplemented with some introductory chapters summarizing the state-of-the-art, the motivations and objectives of the work as well as the main contributions and some suggested lines for future work. It comprises 7 already-published (or accepted for publication) peer-review journal articles which are integral part of this work.

Tesi realitzada al Centre de Projecció Tèrmica - Universitat de Barcelona / The main subject of this thesis is the fabrication of functional titanium dioxide coatings by means of Atmospheric Plasma Spray (APS) and Cold Gas Spray (CGS). Functional role may be understood as the capacity of TiO2 surfaces to respond in a determined way under certain conditions. Firstly, conventional coating processes, sensing mechanisms and overall efficiencies were deeply studied. As regards to experimental results, it was observed that H2 contained in the plasma mixture could reduce TiO2 towards non stoichiometric or stoichiometric compounds such as titanium sub-oxides (TiO2-x) or Magnéli Phases (TinO2n-1) respectively during the in-flight of the particles. Large accumulation of oxygen vacancies in the crystal lattice of rutile led to a donor level to the conduction band. Therefore, a corrosion-resistant ceramic material with a low electrical resistivity was obtained on ceramic tiles. This unexpected procedure led to deposit APS TiO2-x / TinO2n-1 coatings on stainless steel and apply them in electrochemical bi-polar batteries. Then, from the created feedback thin stainless steel and aluminium films, carbon-polymer composites or nickel foams as common standard electrode materials were selected and coated. Produce the active layer of a metal oxide gas sensor using APS fed by TiO2 was still a target to be accomplished. With the aim of offering more innovation to conventional metal oxide sensors, it was determined to build-up the sensing layer on a thin polymeric flexible substrate. It was possible to reach certain spraying conditions that avoided thermal degradation of the polymer. Furthermore, heterogeneous disposition of the coating, where some areas were coated and certain spots uncoated provided electric contact between the electrodes and structure that eased elastic deformation of the film. Satisfactory performances were obtained testing the response of the device in front of a target gas and radiation. Thenceforth, transition to thermally less-aggressive technologies was carried out. It was decided to focus the efforts on CGS, which does not require melting the material for being deposited. Subsequently, nanostructured anatase was used as feedstock in order to achieve photocatalytic layers with large specific surfaces for applying them in the degradation of different contaminants. It was used a powder able to create chemical bonds with the substrate and among the particles at the impact. Unfortunately, feeding system was repeatedly clogged because of the high agglomerating capacity of the powder. Blends were prepared with copper and microstructured TiO2 that flowed appropriately so as to avoid the obstruction of the pipelines. First, Cu/nano-TiO2 coatings were deposited using spraying conditions that favoured the deposition of nanostructured anatase at the top surface, which assured the development of the photocatalytic process. Samples successfully degraded toluene in gaseous phase. On the other hand, micro-TiO2/nano-TiO2 blend was not suitably deposited onto steel. Ceramic particles may not deform plastically. Thus, chemical bonds with the substrate and among particles had to be boosted for building-up the coatings. Substrate surface based on APS TiO2-x with controlled roughness provided composition, hardness and required geometry for adhering nano-TiO2 particles. In this way, CGS nano-TiO2 coatings were tested for degrading phenol and formic acid in liquid phase. The obtained results equalized or even improved the performance of sol-gel coatings. Metallic Ti coatings were previously deposited onto the polymer by CGS for afterwards spraying nano-TiO2, following the know-how gained in CGS nano-TiO2 photocatalysts. Again, lower layer acted as a bond coat between the original substrate and nanostructured anatase. Osteblast cultures were tested on PEEK, CGS Ti on PEEK and CGS nano-TiO2 deposited on CGS Ti layer. Higher cell adhesion, proliferation and differentiation were obtained as long as CGS coatings were applied, which leads to an improved bioactivity of polymeric implants. / El principal objetivo de esta tesis es la fabricación de recubrimientos funcionales de óxido de titanio obtenidos por Atmospheric Plasma Spray (APS) y Cold Gas Spray (CGS). El rol funcional debe ser entendido cómo la capacidad de las superfícies de TiO2 de responder de una manera determinada ante ciertas condiciones. El H2 contenido en el plasma podía reducir el TiO2 hacia compuestos no estequiométricos o estequiométricos como los sub-óxidos de titanio (TiO2-x) o las fases de Magnéli (TinO2n-1). Una gran acumulación de vacantes de oxígeno en la estructura cristalina del rutilo llevó a la formación de un nivel dador hacia la banda de conducción. Este inesperado procedimiento llevó a producir recubrimientos APS TiO2-x / TinO2n-1 sobre acero inoxidable y aplicarlos como electrodos en baterías bi-polares. Posteriormente, se decidió recubrir con este material electrodos típicamente utilizados como láminas finas de acero inoxidable y aluminio, compuestos de carbono-polímero y espumas de níquel. Con la intención de ofrecer más innovación a los sensores convencionales de óxido metálico, se decidió fabricar la capa activa sobre un sustrato polimérico flexible. Fue posible alcanzar ciertas condiciones experimentales que evitaron la degradación térmica del polímero. Se centraron esfuerzos en CGS, que no necesita fundir el material para producir el recubrimiento. De esta forma, anatasa nanoestructurada se utilizó como materia prima con el objetivo de lograr capas fotocatalíticas con gran superfície específica, capaces de degradar diferentes contaminantes. Se utilizó un polvo capaz de crear enlaces químicos con el sustrato. Se prepararon mezclas con otros polvos con el objetivo de mejorar su fluidez y evitar la obstrucción de las tuberías. Primero, recubrimientos Cu/nano-TiO2 fueron depositados utilizando condiciones que favorecieron el anclaje de las partículas de anatasa en la superfície del recubrimiento. Las muestras degradaron tolueno en fase gaseosa con éxito. Por otro lado, la mezcla micro-TiO2/nano-TiO2 no se depositó sobre acero. Se utilizó un sustrato préviamente recubierto con APS TiO2-x. Estos recubrimientos degradaron con éxito fenol y ácido fórmico en fase líquida. Se decidió incrementar la bioactividad del PEEK (polyetheretherketone). Sin embargo, fue posible anclar partículas de TiO2 sobre el polímero previamente recubierto por Ti mediante CGS, obteniendo recubrimientos gruesos con una buena adherencia. Cultivos de osteoblastos fueron analizados sobre PEEK, Ti en PEEK y nano-TiO2 en PEEK. Se obtuvo una mayor adhesión, proliferación y diferenciación celular a medida que los recubrimientos CGS fueron aplicados.

The thesis at hand deals with the modification of cyclic butylene terephthalate (CBT) with the aim to improve its final properties. CBT polymerizes in an entropically-driven ring-opening polymerization into polymerized CBT (pCBT), which is typically brittle. To increase the toughness of pCBT, a series of chemical and physical modifications of CBT with toughening agents and nano-reinforcements have been investigated. The role of the used processing routes on the properties of unmodified pCBT has been studied and in all cases a brittle pCBT has been obtained. However, it was found that a small amount of tetrahydrofuran can toughen pCBT. Nevertheless, this toughening mechanism was found to be only temporarily. Reactive chain extension using low molecular weight, bi- or polyfunctional chain extenders such as epoxy resins or isocyanates was particularly effective and showed a remarkable toughening effect on pCBT. The epoxy- and isocyanatemodified pCBT polymers exhibited increased failure strain in tensile tests while modulus and strength were not significantly affected; contrary to other common toughening methods such as blending with other polymers, plasticization or copolymerization with soft segments. Nanocomposites of toughened CBT and nano-reinforcements such as organo-montmorillonite, graphene and polyhedral oligomeric silsesquioxanes (POSS) were prepared and thoroughly analysed. The organoclay nanocomposites showed an intercalated-flocculated structure with high stiffness and strength together with a semi-ductile deformation behaviour. The organoclay was further modified by tethering the chain extender to the clay surfactant which resulted in an intercalated organoclay. This chain extender-grafted organoclay reacted then with pCBT and therefore could be exfoliated and randomly dispersed in the pCBT matrix during polymerization. A similar strategy was followed in the synthesis of pCBT/graphene nanocomposites. However, graphene exfoliation could not be achieved due to the strong p¿p interactions between the graphene sheets. Binary blends containing a polyisocyanate- grafted graphene showed an improved stiffness and strength due to enhanced compatibility. pCBT/POSS nanocomposites showed a good potential for nano-modification. However, the challenge was to find a compatible POSS type which did not affect the ring-opening polymerization of CBT. Moreover, toughened carbon fibre fabric-reinforced pCBT composites have been prepared applying the developed toughening methods. Interlaminar shear strength, flexural strength and failure strain of the chemically modified composites increased up to 60% with respect to unmodified pCBT composites. This thesis has been prepared in the Centre Català del Plàstic (CCP) and the Department of Materials Science of the Polytechnic University of Catalonia (UPC) in Terrassa, Spain. A part of the experimental work has been accomplished in the Department of Mechanics and Industrial Production, Mondragon Unibertsitatea (Mondragón, Spain) and in the Department of Polymer Engineering of Budapest University of Technology and Economics (Budapest, Hungary). / La presente tesis trata de la modificación del butilén tereftalato cíclico (CBT) con el propósito de mejorar alguna de sus propiedades finales y expandir sus aplicaciones. En presencia de un catalizador y temperatura, el CBT reacciona y a través de un proceso de apertura de anillo, polimeriza dando lugar al pCBT. Sin embargo, el polímero resultante es intrínsecamente frágil. En este trabajo se han estudiado diversas modificaciones tanto físicas como químicas (procesado, extensores de cadena, nanopartículas) con el objetivo de incrementar la tenacidad del pCBT. En primer término se estudió el efecto que la ruta específica de procesado tiene sobre las propiedades y si bien en todos los casos se obtuvo un material frágil, se ha descubierto también que una pequeña cantidad de tetrahidrofurano puede hacer el pCBT más tenaz aunque sea de manera temporal. El uso de extensores de cadena polifuncionales de bajo peso molecular, como resinas epoxídicas o isocianatos ha resultado ser particularmente efectivo. Así en el pCBT modificado con dichos agentes se obtuvieron notables incrementos de tenacidad sin significativa afectación de otras propiedades como el módulo de Young o la tensión de fluencia, como normalmente ocurre en procesos como la plastificación o la copolimerización. Por otra parte se han preparado y analizado diversos nanocompuestos con CBT modificado añadiendo diferentes nanopartículas como montmorillonita, grafeno o polyhedral oligomeric silsesquioxanes (POSS). Los nanocompuestos formados con arcilla exhibieron unas estructuras intermedias entre intercaladas y floculadas, con alta resistencia y rigidez en tracción y deformación a rotura de tipo semi-dúctil. El posterior injerto de un extensor de cadena en la superficie de la arcilla modificada permitió la reacción con el pCBT durante la polimerización, alcanzándose en este caso estructuras con arcilla exfoliada y dispersada a lo largo de la matriz. La aplicación de esta estrategia con el grafeno no dio lugar a su exfoliación debido a las fuertes interacciones existentes entre sus láminas. El uso de partículas POSS tiene un gran potencial para la modificación del pCBT, sin embargo el reto es encontrar una nanopartícula de este tipo que no interfiera con la polimerización de anillo del CBT. Finalmente las estrategias de incremento de tenacidad descritas se han aplicado en la fabricación de compuestos de pCBT reforzados con fibras de carbono. En este caso la resistencia a cizalla interlaminar, a flexión y la deformación a rotura se incrementaron hasta casi un 60% con respecto a los compuestos no modificados. Esta Tesis se ha realizado en el Centre Català del Plàstic (CCP) y en el Departamento de Ciencia de Materiales e Ingeniería Metalúrgica de la Universidad Politécnica de Catalunya (UPC). Asimismo, una parte del trabajo experimental se ha llevado a cabo en el Departamento de Mecánica y Producción Industrial de la Universidad de Mondragón y también en el Department of Polymer Engineering of Budapest University of Technology and Economics (Budapest, Hungría).

In our work we studied some aspects of biochemical quality in the rehabilitation process of degraded soils through the application of sewage sludge. As biochemical quality parameters we focused on the carbon cycle, through total (TCH), extractable (ECH) carbohydrate content, β-glucosidase (GLC), β-galactosidase (GAL), BAA-hydrolysing (BAA), and urease(UR) enzymatic activities, organic carbon (C) and amino acid nitrogen (AAN) contents. We conducted two experiments of sludge application (in containers and in plots) over soils of different texture. The study was supplemented by a work on the standard quality of natural soils of Catalonia and also with an approach to the analytical methodology used in the determination of two of the studied parameters. In the first part we studied the biochemical characteristics of ten natural soils which were representative of Catalan soils. The results showed the wide range of values of carbon and the high dispersion of biochemical parameters, and also that the ranges of obtained values were similar to those of other soils also belonging to Mediterranean areas. Biochemical parameters showed high positive correlations among them. The TCH content was more correlated with organic C and organic N than the enzyme activities. GLC was the activity showing the highest correlation with the organic carbon content. The four enzymatic activities (GLC, GAL, BAA and UR) were more related to the labile than to the total fraction of carbohydrates. The study confirmed the influence of soil type, vegetation or bedrock on the biochemical characteristics of the forest soils group. With respect to the application of sludge, in the first experiment we studied the effect of three sludge types, dehydrated (D), thermally dried (T) and composted (C), added in two different proportions on the biochemical parameters of two degraded soils (clay and sand) from quarrying. Initially an increased value was detected for all biochemical variables (except the UR activity) in the amended soils, CHE being the most enhanced variable. At the end of the experiment the carbohydrates content and the enzyme activities of the mixtures had increased, compared to the control, in a similar value than C, AAN being the most enhanced parameter. The initial differences in the values of GLC depending on the type of sludge (T> D> C) were a reflection of the lability of organic matter provided by the sludge. The overall results indicate that: i) thermal drying accelerates the initial decomposition process of the organic matter which takes place in the soil, ii) composting provides a less labile but more active organic matter, which results in increased mineralization and eventually a more stable organic matter iii) when the sludge was applied in a clay soil a slowing on the development of organic matter was detected. The second experiment consisted of a trial with two degraded soils. Initial (4 days) and final (295 days) samples were analysed in plots where we applied the same sludges with a single dose. In the case of the application of sludge to a sandy-loam soil, the dynamics of mineralization was intense and the impact on biochemical properties one year after the application was not very important. In contrast, the effects on a loam soil, where the dynamics of organic matter was lower, were more important and primarily consisted of an increase of ready available organic carbon.Organic carbon determination by the combustion method was proved to be effective and it was confirmed the inappropriateness of the oxidation method for sludge-soil mixtures. / En la restauració d’activitats extractives és imprescindible la utilització d’un material edàfic de qualitat per abordar degudament la revegetació. Els fangs procedents de EDARs, convenientment dosificats i ben incorporats, poden ser molt útils com a esmena orgànica. En el nostre treball hem estudiat alguns aspectes de qualitat bioquímica en el procés de rehabilitació de sòls degradats a través de l’aplicació de fangs d’EDARs. Com a paràmetres de qualitat bioquímica del sòl ens hem centrat en el cicle del carboni, a través del contingut en carbohidrats totals (CHT) i extractables (CHE) i de les activitats enzimàtiques β-glucosidasa (GLC) i β-galactosidasa (GAL) i com a paràmetres auxiliars en el contingut en Carboni orgànic (C) i Nitrogen aminoacídic (NAA). També hem treballat amb resultats de dues activitats enzimàtiques relacionades amb el cicle del nitrogen, la proteolítica de BAA (BAA) i la ureàsica (UR). Hem portat a terme dues experiències d’aplicació de fangs, una primera en lisímetres i una segona en parcel·les i ambdues amb sòls de diferent textura. El disseny experimental de les dues experiències és d’especial interès ja que planteja estudiar en paral·lel els efectes de l’assecatge tèrmic i el compostatge d’un mateix fang deshidratat. Aquest estudi central de la tesi es complementa amb un treball sobre l’estàndard de qualitat en sòls naturals de Catalunya així com amb aportacions sobre la metodologia analítica per a la determinació de dos dels paràmetres estudiats (C i GLC). Com a primera part de la tesi estudiem les característiques bioquímiques en deu sòls naturals representatius dels sòls catalans. Els resultats mostren ampli rang de valors de carboni i alta dispersió dels paràmetres bioquímics i els rangs obtinguts són similars als de sòls d’altres zones de clima mediterrani. Els paràmetres bioquímics presenten correlacions altes i positives entre ells i alhora una gran dependència del contingut en matèria orgànica del sòl així com del contingut en biomassa microbiana. El contingut en CHT està més correlacionat que les activitats enzimàtiques, amb els continguts de C orgànic i N orgànic del sòl. La GLC és l’activitat enzimàtica més relacionada amb el contingut de carboni orgànic del sòl. Les quatre activitats enzimàtiques (GLC, GAL, BAA i UR) estan més lligades a la fracció làbil de carbohidrats que a la total i les activitats GAL, UR i BAA estan molt relacionades entre elles. L’estudi ha permès constatar la influència del tipus de sòl, roca mare o vegetació en les característiques bioquímiques del grup de sòls forestals. Pel que fa a l’aplicació de fangs, en la primera experiència hem estudiat l’efecte de tres fangs: deshidratat (D), assecat tèrmicament (T) i compostat (C) en dues dosis (per assolir un 3 % i 6 % de matèria orgànica) sobre els paràmetres bioquímics de dos sòls control degradats (argilós i sauló) provinents de pedreres (1% C i 0,1% C). L’assaig es realitza en condicions de laboratori i consta de tres mostreigs (7, 67 i 267 dies). Inicialment es detecta un increment del valor per totes les variables bioquímiques (a excepció de l’activitat UR) en les barreges sòl-fang i el contingut en CHE és la variable més incrementada. Al final de l'experiència les barreges tenen uns valors de carbohidrats i activitats enzimàtiques incrementats respecte del control de forma similar a l’increment final en matèria orgànica, i el contingut en NAA és la variable més incrementada respecte del sòl control. Les diferències en els valors de l’activitat enzimàtica GLC a l’inici en funció del tipus de fang (T>D>C) són un reflex de la labilitat de la matèria orgànica aportada pels fangs. El conjunt de resultats indiquen que: i) l’assecat tèrmic accelera el primer procés de descomposició de la matèria orgànica; ii) el compostatge proporciona una matèria orgànica no tan làbil, però amb més activitat enzimàtica que comporta més mineralització i, amb el temps, una matèria orgànica més estable i iii) l’evolució de la matèria orgànica es frena quan els fangs s’apliquen en un sòl argilós. La segona experiència consta d’un assaig d’aplicació de fangs en dos terrenys degradats i analitzem les mostres inicials (4 dies) i finals (295 dies) de parcel·les on s’han aplicat els mateixos tres fangs de l’experiència en lisímetres, però amb una única dosi (10 Mg/ha, en matèria seca). En el cas de l’aplicació de fangs al sòl franc-arenós (sòl amb baix contingut en matèria orgànica i alta activitat enzimàtica) la dinàmica de mineralització ha estat intensa i la incidència sobre les propietats bioquímiques del sòl, un any després de l’aplicació dels fangs, ha estat molt poc acusada. Contràriament, els efectes sobre el sòl franc, on la dinàmica de la matèria orgànica ha estat menor, són més importants i bàsicament han significat l’augment del contingut en matèria orgànica i la millora de la potencialitat de la matèria orgànica d’obtenir formes assimilables de carboni. Els resultats dels aspectes metodològics indiquen que la determinació de carboni orgànic per combustió ha resultat eficaç i confirmen la manca d’idoneïtat del mètode d’oxidació per a mostres de sòl-fang. Pel que fa a l’estudi de l’activitat β-glucosidasa i β-galactosidasa en sòls, el nostre treball representa una contribució a la descripció detallada del procediment analític i a la incidència sobre el valor de l’activitat de la determinació a partir de mostra humida o bé assecada a l’aire.

According to a study of the European Commission, approximately one million hips are replaced by prostheses worldwide every year. The interaction of the human body with foreign materials that are subjected to alternating mechanical load in a highly corrosive environment still provides challenges. The main factors affecting prosthesis failure are stress shielding effect and poor osseointegration. In this thesis the problem of prosthesis failure has been approached from the material and from the osseointegration point of view trying to give a global solution to the problem. Niobium and hafnium, which are demonstrated to be totally biocompatible, were used to design a Ti-based alloy. The effect of the alloying elements regarding microstructure and elastic modulus was studied and the best composition was deeply characterized in terms of microstructure, elastic modulus, corrosion resistance and superficial energy. Recombinant fragments of fibronectin were synthesised spanning the cell attachment site and the heparin binding domain which are important for cell viability. These motifs were used to functionalise the surface of the TiNbHf alloy. Two tethering methods were studied: physisorption and silanisation. Silanisation was not used before to immobilise fibronectin recombinant fragments onto metallic substrates and in this thesis, its good performance was demonstrated. In vitro studies were made with each fragment and with different combinations of the fragments, which showed the importance of the heparin binding domain to obtain a cell response equivalent to that of fibronectin in terms of cell adhesion, proliferation and differentiation. / De acuerdo con un estudio de la Comisión Europea, aproximadamente un millón de caderas son remplazadas por prótesis en el mundo anualmente. La interacción del cuerpo humano con materiales externos sujetos a una carga mecánica alternante en un medio altamente corrosivo todavía presenta ciertos desafíos. Los factores que contribuyen principalmente al fallo de una prótesis son el apantallamiento de cargas y la pobre osteointegracion. En la presente tesis el problema de la fallida de prótesis ha sido abordado desde el punto de vista del material y de la osteointegracion en un intento de dar una solución global al problema. El niobio y el hafnio, cuya total biocompatibilidad ha sido demostrada, se han utilizado para diseñar una aleación de titanio. El efecto de dichos aleantes respecto a la microestructura y el módulo elástico ha sido estudiado y la mejor composición ha sido profundamente caracterizada en términos de microestructura, módulo elástico, resistencia a la corrosión y energía superficial. Fragmentos recombinados de fibronectina han sido sintetizados abarcando la zona de adhesión celular y la unión de heparina, las cuales son esenciales para la viabilidad celular. Dichos motivos han sido utilizados para funcionalizar la superficie de la aleación TiNbHf. Dos métodos de unión diferentes han sido estudiados: fisisorción y silanización. La silanización es un método que no se ha utilizado hasta el momento para inmovilizar fragmentos de fibronectina sobre superficies metálicas y en la presente tesis su idoneidad ha sido demostrada. Finalmente, estudios celulares in vitro se han llevado a cabo con cada fragmento y con diferentes combinaciones de ambos, lo cual ha mostrado la importancia de la zona de unión de heparina para obtener una respuesta celular equivalente a la obtenida con la molécula de fibronectina en cuanto a adhesión celular, proliferación y diferenciación.

Leather is a natural material that can be used in different environments and often under aggressive environmental conditions that may cause premature ageing. Since upholstery leather is considered a very high-tech product, a long service life is expected by the costumer. According to different studies carried out on historical/ancient leathers by leather conservation centers and museums, leather also is strongly affected by these three main environmental parameters: temperature, relative humidity, and UV radiation. The aim of this work is to study the effect of the environment exposure, to identify the most important variables affecting this weathering process and to check for interactions among the three factors on the degradation and leather ageing on wet-blue and wet-white upholstery leather, applying the leather to natural weathering, tropical environmental exposure and finally a combination of the three critical factors. The tests were carried out on Spanish pickled cattle hides. Two types of tanned leather were tested: on the one hand, chrome tanned leather and on the other hand, wet-white tanned leather using tetrakishydroxymethylphosphonium sulphate (THPS) and silicate-phenolic synthetic and retanned with protein-amide polymer. Both types of leathers were finished using common industrial formulation. Firstly, the work was undertaken to better understand the effect of degradation of chrome tanned leather and wet-white leather and the physical and chemical processes occurring during long-term exposure to outdoor conditions. The samples were tested before and after 20, 40, 80, 120 and 180 days of exposure. Increasing the levels of the three critical weathering variables, the leathers were exposed to tropical environment using a climatic chamber at 70ºC and 95% relative humidity during 7, 14 and 21 days. Additionally half of the leathers were exposed to UV radiation for 4 days. Finally, the leathers were exposed to accelerating ageing test using a multilevel centralized factorial experimental design and an analysis of variance (ANOVA) with 3 variables and 2 levels (23). The evaluation of the leathers was carried out with physical, fastness, chemical and organoleptic properties of the leathers. With the natural weathering studies, wet-white leather and chrome-tanned leather show a different behavior to leather ageing. The loss in properties in chrome-tanned leather increases steadily until 40 days exposure, and after this point the leather stabilizes and no longer degrades. In wet-white leather, however, there is a progressive loss in properties but stabilization does not occur until a period of exposure of 80-120 days. Tropical environmental exposure causes physical and chemical degradation of both types of tanned leather. In chrome-tanned leather, the loss of all properties occurs progressively over time, in wet-white leather it occurs only after 7 days exposure, and is followed by carbonization of the leathers after 14 days exposure. Additionally, when wet-white samples are exposed for long periods at high relative humidity are attacked by fungi. Resistance and dimensional stability of wet-white leather both in accelerated ageing tests and natural weathering exposure is higher than that of chrome-tanned leather. However, these leathers have the disadvantage of not resisting simultaneous exposure to high temperatures and high relative humidity, that's to say, tropical environmental conditions. Results from experimental designs prove again that chrome-tanned leather and wet-white leather have a different ageing behavior. Whereas chrome-tanned leathers are strongly affected by UV radiation, wet-white leathers are strongly affected by relative humidity. Additionally, no correlation has been found between ageing caused by natural weathering and that caused under controlled conditions in the laboratory. / La pell és un material natural que pot ser utilitzat en diferents ambients i molt sovint pot ser sotmès a condicions ambientals agressives provocant el seu envelliment prematur. Segons diferents estudis portats a terme en pells històriques procedents de centres de conservació de la pell i museus, la pell es veu afectada pels tres paràmetres ambientals principals: temperatura, humitat relativa i radiació UV. L’objectiu d’aquest treball és estudiar l’efecte de l’exposició ambiental, identificar les variables més importants que afecten al procés d’envelliment i buscar les interaccions entre els tres factors, en la degradació i envelliment de la pell adobada al crom i pell adobada wet-white per tapisseria, sotmetent la pell a exposició directa a la intempèrie, exposició a ambient tropical artificial i finalment a una combinació dels tres factors crítics. Els assajos es porten a terme amb pell vacuna piquelada, es preparen dos tipus de pell: pell adobada al crom, i pell adobada wer-white utilitzant sulfat de tetrakishidroximetilfosfoni (THPS) i sintètic silicat-fenòlic readobat amb polímer de proteína-amida. Les pells s’acaben utilitzant una formulació industrial estàndard. Inicialment el treball pretén entendre millor l’efecte de la degradació de la pell adobada al crom i pell adobada wet-white, i els processos físics i químics que ocorren durant una exposició prolongada a les condicions ambientals exteriors. Les mostres s’analitzen abans i després de 20, 40, 80, 120 i 180 dies d’exposició. Incrementant els nivells de les tres variables crítiques d’envelliment, les pells s’exposen a un ambient tropical utilitzant una cambra climàtica a 70ºC i 95% d’humitat relativa durant 7, 14 i 21 dies d’exposició. Addicionalment la meitat de les pells s’exposen a radiació UV durant 4 dies. Finalment, les pells s’exposen a un test d’envelliment accelerat utilitzant un disseny experimental factorial centralitzat, com a eina estadística per estimar els efectes dels paràmetres es treballa amb un anàlisis de variància (ANOVA) amb 3 variables i 2 nivells cadascun. L’avaluació de les pell es porta a terme a través de l’anàlisi de propietats físiques, químiques i organolèptiques de les pells. En els estudis d’exposició natural les pells adobades al crom i les pells adobades wet-white mostren un comportament diferent a l’envelliment. Mentre que per la pell adobada al crom la pèrdua de propietats físiques es produeix als 40 dies d’exposició i després d’aquest punt la pell s’estabilitza i no es degrada més, en el cas de la pell adobada wet-white es produeix una pèrdua progressiva de les propietats però l’estabilització no es produeix fins als 80-120 dies. L’exposició a un ambient tropical artificial causa una degradació física i química en els dos tipus de pells. En la pell adobada al crom, la pèrdua de propietats ocorre progressivament en el temps, mentre que en la pell adobada wet-white això només succeeix després de 7 dies d’exposició, seguit d’una carbonització després de 14 dies d’exposició. A més, quan la pell adobada wet-white s’exposa a períodes llargs d’humitat relativa alta és atacada per fongs. La resistència i l’estabilitat dimensional de la pell adobada wet-white, tant en l’assaig d’envelliment accelerat com en l’exposició ambiental natural, és molt superior a la de la pell adobada al crom. Tanmateix, aquesta pell té la desavantatge de no resistir simultàniament l’exposició a elevada temperatura i elevada humitat relativa, condicions de l’ambient tropical. Els resultats dels dissenys experimentals demostren una altra vegada que la pell adobada al crom i la pell adobada wet-white tenen un comportament a l’envelliment molt diferent. Mentre que la pell adobada al crom es veu molt afectada per la radiació UV, la pell adobada wet-white està afecta per la humitat relativa. Addicionalment, no es troba cap correlació entre l’envelliment causat per exposició ambiental natural i el causat sota condicions controlades al laboratori.

Historical decorated glass and glazed ceramics are studied with the object to determine the technology of production and to relate it with the optical properties (colour, shine, opacity). Four different case of study are investigated: production technology and replication of lead antimonate yellow glass from New Kingdom Egypt and the Roman Empire, technology of production of polychrome lustre, analyses of Syrian lustre pottery (12th–14th centuries AD) and study of color and dichroism of silver stained glasses. These different coloured glazes or glasses have in common to be produced by the presence of micro or nanoparticles embedded into the glaze which give their special optical effect. Chemical and microstructural analyses are performed using a selection of complementary Microscopic and Spectroscopic techniques that are the most adequate for the analyses of each decoration. Physical optical properties are also modeled and measured by means of UV-Vis spectroscopy. The composition and structure of the different phases formed during the processing of the decorations in historical times is obtained with the object to learn about their stability and processing conditions and to relate them to their optical properties

Today we are experiencing an "eco friendly boom"; which includes the developing of ecological processes that have a smaller impact in the environment. This is the reason that prompted me to carrying out this thesis; the aim is to use a vegetable extract as a sustainable product for the pre-tanning processes. This study considers the use of the fruit of the Tara tree as a raw material source of tannins with low carbon footprint and proposes alternatives to avoid or reduce the use of commercial vegetable extracts, synthetic products and mineral salts that require non sustainable processes. Various experimental designs have been developed as to obtain new tailored Tara tannins by both chemical and physical modification, in order to obtain a higher percentage of tannins, and therefore improve its tanning capability, also reducing the astringency and improving the penetration of the tannin molecules through the leather structure. In chemical modifications, several aqueous extractions at different temperatures and combined with some chemicals, have been developed and optimized in order to increase the tannin content and reduce the astringency. The degree of hydrolysis has controlled by measuring the Gallic acid content by means of HPLC (High performance liquid Chromatography). In the physical modification part, the Tara has been milled and sieved, at several particle sizes, with the aim of obtaining a smaller molecular size. Both chemical and physical modifications were tested in hides, in a wet-white pre-tanning process, combining them with the fewest possible commercial vegetable extracts and syntans. The formulations have been optimized by experimental design. All the resulting leather products and final baths have been analyzed with physical and chemical tests respectively, to determine if they comply with the parameters established by the IULTCS (International Union of Leather Technologists and Chemists Societies). Finally, a life cycle assessment has been developed, in order to determine the environmental improvement of the new modified product, obtained in this thesis. This thesis is also supported with articles published in magazines specialized in the Leather sector. There are two articles published in the Journal of the American Leather Chemists Association (JALCA), named: *Low carbon products for the design of innovative leather processes. Part I: determination of the optimal chemical modification of tara. . (JALCA, Vol. 108, pag. 386-391, 2013) *Low carbon products for the design of innovative leather processes. Part II: determination of the optimal physical modification of tara. (JALCA, Vol. 109, pag. 25-31, 2014) One article pending to be published in the Journal of AQEIC (Spanish Leather Chemists Association) Application of Sustainable tannins with Low carbon footprint,And presented in the 62nd Congress of AQEIC, Lorca (Murcia), May 10th and 11th, 2013 Presentation: "Aplicación de taninos sostenibles con baja huella de carbono"

Polymers are becoming preferred materials in biomedical applications because of their vast diversity of properties, functionalities and applications. Properties as mechanical strength, stability against degradation, biocompatibility and biodegradability, among others, have been attractive for different medical applications. One of the most interesting applications of these materials is drug delivery systems. Biodegradable polymers and copolymers are the preferred materials for the manufacture of a variety of devices for temporal applications in medicine and pharmacology; these biodegradable polymers can be chemically synthesized or biologically produced. Biotechnological polymers have attracted much attention because two main advantages; first, they are produced from renewable resources; and second, as they are biologically produced they are biocompatible, biodegradable and bioresorbable materials. Thus, modification of biotechnological polymers to obtain specific properties or functionalities is a good strategy for the development of promising biomedical materials. In this Thesis the water soluble biotechnological polymer poly(ß,L-malic acid) (PMLA) was modified to change its hydrophilic character to produce non water-soluble polymers capable of forming particulate systems for drug encapsulation and controlled release. PMLA is a polyester-3 with a pendant carboxylic group; it is biocompatible, biodegradable and bioresorbable. The carboxylic side group can be substituted in order to modify the properties of the polymer. The polymer as polyelectrolyte, is also water-soluble. Different strategies were used for polymer derivatization: direct esterification and amidation through the activation of the carboxylic side groups with carbodiimides; ionic complex formation with a cationic drug (Doxorubicin); and esterification with aliphatic long chains by a two step method employing thiol-ene click reactions. Obtained PMLA derivatives resulted in hydrophobic or amphiphilic polymers, which were appropriated for nanoparticle formation, either by emulsion solvent evaporation or by precipitation dialysis techniques. Derivatives physicochemical characterization was made by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography (GPC) and differential scanning calorimetry. Hydrolytic degradation was followed by GPC and 1H NMR, while particles were observed by scanning electron microscopy and their size and surface charge characterized by dynamic light scattering and ζ-potential measurement. Assays of drug encapsulation and release were also performed and cytotoxicity tests were done on cancer cell lines. Nanoparticles (100-300 nm aprox.) were obtained from all PMLA derivatives, except for the ionic complex which formed microparticles. Nanoparticles showed potential as drug delivery systems since they were able to encapsulate the anticancer drugs Temozolomide and Doxorubicin, as well as the model drugs Theophylline and Carbamazepine. Drug release was assessed under physiological conditions; the release rate was found to depend on encapsulation method, drug and polymer derivative. Hydrolytic degradation assays showed that free malic acid and the organic compound derived from the reagent used for modification were the last products of aqueous degradation of PMLA derivatives. Cytotoxicity tests demonstrated the low toxicity of the synthesized derivatives. Results generated in this Thesis suggest that the biotechnological polymer PMLA is a material of interest as a platform for the design and development of biodegradable drug delivery systems with potential in the therapy of diseases considered today challenging for pharmacologic treatment.

La recerca de nous catalitzadors sòlids bàsics de tipus Brønsted ha estat en el punt de mira de nombrosos estudis recents, degut al seu gran potencial per a dur a terme reaccions de condensació ald-olica. Aquests materials sòlids eviten l'ús industrial de solucions aquoses de tipus KOH i NaOH, reduint significativament els problemes de generació de residus, corrosió o no reutilització dels catalitzadors. En els darrers anys, ha crescut l'interès en l'estudi dels hidròxids dobles laminars (layered double hydroxides, HDL) o compostos de tipus hidrotalcita, com a catalitzadors de nombroses reaccions, o bé, en altres aplicacions.Per tal de generar catalitzadors sòlids bàsics de tipus Brønsted, un HDL de Mg-Al, tractat tèrmicament, pot ser reconstruït degut al seu conegut efecte memòria. La reconstrucció es realitza per contacte del sòlid amb vapor d'aigua (fase gas) o per immersió en aigua liquida (fase liquida), ambdues en atmosfera inert. Un aspecte en discussió es la relació entre el procediment de rehidratació aplicat i l'activitat catalítica dels HDL de Mg-Al reconstruïts. En aquest treball s'han estudiat detingudament els processos de rehidratació en fase gas o en fase liquida. Donat que el procés de rehidratació porta a la formació d'un material de tipus meixnerita, el qual presenta centres bàsics de Brønsted en l'espai interlaminar, es mostra que l'accessibilitat cap a aquests centres bàsics es un factor determinant de l'activitat d'aquests catalitzadors en reaccions de condensació aldòlica. Per altra banda, s'ha estudiat també la sensibilitat dels catalitzadors HDL de Mg-Al reconstruïts en fase gas, a l'addició de promotors alcalins, per tal d'assegurar la seva influencia en l'activitat catalítica.La recerca descrita en aquest treball de tesi s'ha centrat en l'estudi dels procediments d'activació/rehidratació, i en conseqüència, en la morfologia dels catalitzadors de tipus hidrotalcita. Les propietats bàsiques s'han caracteritzat mitjançant diferents tècniques, com la desorció a temperatura programada de diferents molècules sonda, i mitjançant reaccions model del tipus condensació aldòlica entre citral-cetones. Una altra alternativa interessant és l'ús de líquids iònics, amb una amplia aplicació com a solvents, degut a les seves propietats físiques i químiques. L'ús dels líquids iònics amb propietats bàsiques, pot proporcionar catalitzadors eficients en moltes reaccions de condensació aldòlica. En aquest sentit, s'analitzen diferents aspectes com l'ús d'un líquid iònic suportat (l'hidròxid de colina), la seva activitat catalítica en diverses reaccions de condensació aldòlica i la caracterització de les propietats bàsiques. / The research about the use of new solid Brønsted-type basic catalysts has been the focus of many recent studies because of their potential for aldol condensation reactions. Besides, these solid materials avoid the industrially use of KOH and NaOH reducing several problems such as waste production, corrosion and not recovery of the catalysts. In recent years, there has been a growing interest in layered double hydroxides (LDH) or hydrotalcite-like compounds to perform numerous catalytic reactions and other applications. In order to provide solid Brønstedtype basic catalysts, a thermally treated Mg-Al LDH can be reconstructed due to its known memory effect, by rehydration in contact with water vapour or immersed in liquid water under decarbonated atmosphere. The catalytic performance of a reconstructed Mg-Al LDH in relation to the rehydration procedure applied is not well understood. In this work, careful studies of rehydration procedures (gas or liquid phase) over decomposed Mg-Al LDH have been performed. Since the rehydration process leads to a meixnerite-like material, having Brønsted basic sites in the interlayer space, it is shown that accessibility towards these basic sites is a key factor determining the performance of the catalysts in aldol condensation reactions. The sensitivity of gas-phase reconstructed Mg-Al LDH to the addition of alkaline promoters has been also studied to assess their influence on the catalytic performance. The research described in this thesis has focussed on getting more insight in the activation/rehydration procedure and consequently, in the final morphology of hydrotalcite-like compounds. The basic properties have been characterised by several techniques such as temperature programmed des orption of different probe molecules and by illustrative test reactions suchas the liquid-phase aldol condensation between citral-ketones. Another interesting alternative is the use of ionic liquids, which have attracted a large attention as solvents in recent years, due to their physical and chemical properties. Besides, the use of ionic liquids with basic properties could provide efficient catalysts for several condensation reactions. In this area, we also report the use of a supported ionic liquid (choline hydroxide), its catalytic performance in aldol condensation reactions and the characterisation of basic properties.