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UPCommons - E-prints UPC Universitat Politècnica de Catalunya (81,369 recursos)
E-prints UPC cobreix dues finalitats: per una banda, és el dipòsit institucional de la UPC que recull els articles de revista, les comunicacions de congrés i els reports de recerca generats en les activitats de recerca del personal docent i investigador de la universitat; per l'altra, és una eina que permet accelerar la producció científica, allotjant versions de documents prèvies a la publicació en una revista o a les actes d’un congrés.

Articles de revista

Mostrando recursos 1 - 20 de 479

1. Transportation conditions for prompt use of Ex Vivo expanded and freshly harvested clinical-grade bone marrow mesenchymal stromal/stem cells for bone regeneration - Varonesi, E; Murgia, A; Caselli, A; Grisendi, G; Piccinno, M.S; Rasini, V; Giordano, Roberto; Montemurro, T; Bourin, P; Sensebe, L; Rojewski, M.T; Schrezenmeier, H; Layrolle, P; Ginebra Molins, Maria Pau; Penaitescu, C.B; Gomez Barrena, E; Catani, F; Paolucci, P; Burns, J.S; Dominici, M
Successful preliminary studies have encouraged a more translational phase for stem cell research. Nevertheless, advances in the culture of human bone marrow-derived mesenchymal stromal/stem cells (hBM-MSC) and osteoconductive qualities of combined biomaterials can be undermined if necessary cell transportation procedures prove unviable. We aimed at evaluating the effect of transportation conditions on cell function, including the ability to form bone in vivo, using procedures suited to clinical application. hBM-MSC expanded in current Good Manufacturing Practice (cGMP) facilities (cGMP-hBM-MSC) to numbers suitable for therapy were transported overnight within syringes and subsequently tested for viability. Scaled-down experiments mimicking shipment for 18 h...

2. Mechanical properties and in vitro biological response to porous titanium alloys for intervertebrae implants - Gil Mur, Francisco Javier; Punset Fusté, Miquel; Guillem Martí, Jordi; Molmeneu Trias, Meritxell; Calero, Jose Antonio
The generation of titanium foams is a promising strategy for modifying the mechanical properties of intervertebral reinforcements. Thus, the aim of this study was to compare the in vitro biological response of Ti6Al4V alloys with different pore sizes for use in intervertebral implants in terms of the adhesion, proliferation, and differentiation of pre-osteoblastic cells. We studied the production of Ti6Al4V foams by powder metallurgy and the biological responses to Ti6Al4V foams were assessed in terms of different pore interconnectivities and elastic moduli. The Ti6Al4V foams obtained had similar porosities of approximately 34%, but different pore sizes (66 µm for fine...

3. Silver deposition on titanium surface by electrochemical anodizing process reduces bacterial adhesion of Streptococcus sanguinis and Lactobacillus salivarius - Gil Mur, Francisco Javier; Godoy Gallardo, María; Mas Moruno, Carlos; Fernandez Calderon, M.Coronada; Perez Giraldo, Ciro; Manero Planella, José María; Albericio Palomera, Fernando; Rodríguez Rius, Daniel
Bacterial infection represents a major cause of implant failure in dentistry. A common approach to overcoming this issue and treating peri-implant infection consists in the use of antibiotics. However, the rise of multidrug-resistant bacteria poses serious concerns to this strategy. A promising alternative is the use of antimicrobial peptides due to their broad-spectrum activity against bacteria and reduced bacterial resistance responses. The aim of the present study was to determine the in vitro antibacterial activity of the human lactoferrin-derived peptide hLf1-11 anchored to titanium surfaces. To this end, titanium samples were functionalized with the hLf1-11 peptide either by silanization methods...

4. Relevance of the setting reaction to the injectability of tricalcium phosphate pastes - Ginebra Molins, Maria Pau; Montufar Jiménez, Edgar Benjamin; Maazouz, Yassine
The ai m of the present work was to analyze the influence of the setting reaction on the injectability of tricalcium phosphate (TCP) pastes. Even if the injection was performed early after mixing powder and liquid, powder reactivity was shown to play a significan t role in the injectability of TCP pastes. Significant differences were observed between the injection behavior of non - hardening β - TCP pastes and that of self - hardening α - TCP pastes. The differences were more marked at low liquid - to - powder ratios, using fi ne powders and injecting through thin needles. α - TCP was in general less injectable than β - TCP and required higher injection loads. Moreover, clogging...

5. Hardness of FRHC-Cu Determined by Statistical Analysis - Roa Rovira, Joan Josep; Martínez López, Mónica; Rayón Encinas, Emilio; Ferrer Cruselles, Núria; Espiell Álvarez, Ferran; Segarra Rubi, Merce
A statistical indentation method has been employed to study the hardness value of fire-refined high conductivity copper, using nanoindentation technique. The Joslin and Oliver approach was used with the aim to separate the hardness (H) influence of copper matrix, from that of inclusions and grain boundaries. This approach relies on a large array of imprints (around 400 indentations), performed at 150 nm of indentation depth. A statistical study using a cumulative distribution function fit and Gaussian simulated distributions, exhibits that H for each phase can be extracted when the indentation depth is much lower than the size of the secondary phases. It is found that the...

6. A novel peptide-based platform for the dual presentation of biologically-active peptide motifs on biomaterials - Gil Mur, Francisco Javier; Mas Moruno, Carlos; Fraioli, Roberta; Albericio Palomera, Fernando; Manero Planella, José María
Biofunctionalization of metallic materials with cell adhesive molecules derived from the extracellular matrix is a feasible approach to improve cell–material interactions and enhance the biointegration of implant materials (e.g., osseointegration of bone implants). However, classical biomimetic strategies may prove insufficient to elicit complex and multiple biological signals required in the processes of tissue regeneration. Thus, newer strategies are focusing on installing multifunctionality on biomaterials. In this work, we introduce a novel peptide-based divalent platform with the capacity to simultaneously present distinct bioactive peptide motifs in a chemically controlled fashion. As a proof of concept, the integrin-binding sequences RGD and PHSRN...

7. Low modulus Ti–Nb–Hf alloy for biomedical applications - González, Marta; Peña, Javier; Gil Mur, Francisco Javier; Manero Planella, José María
ß-Type titanium alloys with a low elastic modulus are a potential strategy to reduce stress shielding effect and to enhance bone remodeling in implants used to substitute failed hard tissue. For biomaterial application, investigation on the mechanical behavior, the corrosion resistance and the cell response is required. The new Ti25Nb16Hf alloy was studied before and after 95% cold rolling (95% C.R.). The mechanical properties were determined by tensile testing and its corrosion behavior was analyzed by potentiostatic equipment in Hank's solution at 37 °C. The cell response was studied by means of cytotoxicity evaluation, cell adhesion and proliferation measurements. The...

8. Implant-abutment connections: influence of the design on the microgap and their fatigue and fracture behavior of dental implants - Gil Mur, Francisco Javier; Herrero Climent, Mariano; Lázaro, Pedro; Rios Santos, Jose Vicente
Microgap between implant and abutment can produce biological and mechanical problems such as peri-implantitis and/or fatigue failures. The aim of this study was to evaluate microgap size and fatigue behavior of external and internal connections. In both systems the torque to tighten the abutment screw of single crown abutments was 45 Ncm. Fifty implants for each connection type were studied. One subgroup (n=5) was used by the observation and evaluation of the microgap, other (n=5) was tested for fracture strength and the other (n=40) was subjected to dynamic loading. The internal connection presents a lower microgap than the external ones. From fatigue results,...

9. Sheets of branched poly(lactic acid) obtained by one step reactive extrusion calendering process: Physical Aging and Fracture Behaviour - Cailloux, Jonathan; Santana Pérez, Orlando Onofre; Franco-Urquiza, Edgar; Bou, Jordi; Carrasco Alonso, Félix Ángel; Maspoch Rulduà, Mª Lluïsa
Peer Reviewed

10. Tendencias en el campo de la fundición inyectada - Martín Fuentes, Enrique; Menargues Muñoz, Sergi; Picas Barrachina, Josep Anton; Baile Puig, Maria Teresa
Este artículo recoge una visión actualizada de la problemática en el campo de la fundición inyectada, fundamentalmente en la industria de componentes de aluminio. Se muestran las principales limitaciones y se expone cómo la conformación en estado semisólido es una de las alternativas para resolver parte de esos inconvenientes.

11. Mechanical propertiesand in vitro biological response toporoustitaniumalloysprepared for useinintervertebralimplants - Caparrós Vázquez, Cristina Maria; Guillem Martí, Jordi; Molmeneu Trias, Meritxell; Punset Fusté, Miquel; Gil Mur, Francisco Javier
The generation of titanium foams is a promising strategy for modifying the mechanical properties of intervertebral reinforcements. Thus, the aim of this study was to compare the in vitro biological response of Ti6Al4V alloys with different pore sizes for use in intervertebral implants in terms of the adhesion, proliferation, and differentiation of pre-osteoblastic cells. We studied the production of Ti6Al4V foams by powder metallurgy and the biological responses to Ti6Al4V foams were assessed in terms of different pore interconnectivities and elastic moduli. The Ti6Al4V foams obtained had similar porosities of approximately 34%, but different pore sizes (66 µm for fine...

12. Properties of POSS blends with pCBT, PMMA, PC and POM thermoplastics - Abt, Tobias Martin; Sánchez Soto, Miguel; Illescas Fernandez, Silvia; Arostegui, Asier
The influence of the functionalisation of fully or partially condensed POSS cages on the properties of engineering thermoplastic-based nanocomposites is studied. POSS with different organic substituents were selected in accordance with the structure and chemical composition of the host polymer and melt mixed with the corresponding matrix. In general, good dispersion at the nanoscale level was achieved upon the addition of some functionalised POSS, leading to a remarkable increase on the thermal decomposition temperature under nitrogen atmosphere. However, for the polymers having high decomposition temperatures, there were no significant changes on the thermal properties of the nanocomposites. On the other hand, the dispersion of the POSS, whatever its functionalisation was,...

13. Influence of polyhedral oligomeric silsesquioxanes on thermal and mechanical properties of melt-mixed poly(methyl methacrylate)/polyhedral oligomeric silsesquioxanes composites - Illescas Fernandez, Silvia; Arostegui, Asier
In this study, the influence of the functionalization of fully or incomplete condensed polyhedral oligomeric silsesquioxanes composites (POSS) nanoparticles on the properties of poly(methyl methacrylate) (PMMA)-based composites has been studied. POSS with different organic substituents (methacryl, methacrylateisooctyl and trisilanolphenyl) are taken into account and added to the PMMA matrix by direct melt blending at loadings between 0 and 5 wt%. Significant differences in compatibility were observed depending on the structure of nanoparticles. POSS aggregation occurred during blending producing micron-sized aggregates in the composites. The thermal decomposition temperature of the composites with good dispersion of POSS aggregates increased under oxidative conditions....

14. Characterisation and modelling of prestrained viscoelastic films - Martinez-Agirre, Manex; Illescas Fernandez, Silvia; Elejabarrieta, María Jesús
The goal of the present work is to characterise the influence of static prestrain on the elastic and dissipative properties of constrained viscoelastic films. Dynamic mechanical analysis (DMA) technique is considered for measuring the dynamic properties under several static prestrain levels, and a new material constitutive model is presented for characterising the frequency–prestrain dependence of the viscoelastic material. The results indicate that the static prestrain strongly affects the elastic and dissipative properties of the analysed viscoelastic material. The proposed material constitutive model properly describes the frequency–prestrain dependence of the tested viscoelastic material.

15. Corrosion damage in WC-Co cemented carbides: residual strength assessment and 3D FIB-FESEM tomography characterisation - Tarragó Cifre, Jose María; Fargas Ribas, Gemma; Jiménez Piqué, Emilio; Felip, Alba; Isern, Lluis; Coureaux Mustelier, David; Roa Rovira, Joan Josep; Al-Dawery, Ihsan; Fair, Jonathan; Llanes Pitarch, Luis Miguel
The effect of corrosion damage on cemented carbides was investigated. The study included residual strength assessment and detailed fractographic inspection of corroded specimens as well as detailed 3D FIB-FESEM tomography characterisation. Experimental results point out a strong strength decrease associated with localised corrosion damage, i.e. corrosion pits acting as stress raisers, concentrated in the binder phase. These pits exhibit a variable and partial interconnectivity, as a function of depth from the surface, and are the result of heterogeneous dissolution of the metallic phase, specifically at the corrosion front. However, as corrosion advances the ratio between pit depth and thickness of...

16. High temperature scratch testing of hard PVD coatings deposited on surface treated tool steel - Pujante, Jaume; Vilaseca, Montserrat; Casellas, Daniel; Riera Colom, María Dolores
Scratch testing is one of the most usual characterisation techniques for systems with thin hard coatings. Scratch tests are performed at run at room temperature, due to the risk of degradation of the indenter diamond tip at high temperature and added test complexity. However, results obtained at room temperature may differ from the final system performance in high temperature applications, due to factors such as substrate thermal softening. In this work, a simple and a robust test for the mechanical characterisation of hard PVD coatings at high temperature and open atmosphere has been developed, based on a modification of the scratch...

17. Low Sr doping effects on critical current density and pinning mechanism of YBa2Cu3O7-x single crystals - Lopes, R.F.; Vieira, Valdemar das Neves; Teixeira Dias, Fábio; Silva, D.L.da; Pureur, P; Schaf, J; Roa Rovira, Joan Josep
We report on isotherm dc magnetization hysteresis loops, M(H) to 70K ¿ T ¿ 82.5K of YBa2-xSrxCu3O7-x (x = 0, 0.02 and 0.1) single crystals with the purpose to study the influence of the low Sr doping effects on the YBa2Cu3O7-¿ critical current density, JC(H) and normalized flux pinning force density, f(h). The M(H) measurements were performed in a commercial SQUID magnetometer with H ¿ 50kOe applied parallel to the c axis of the samples. The extended Bean critical state model was applied to JC(H) determination. The magnetic irreversibility fields, Hirr(T) were obtained from M(H) loops. The f(h) behavior was...

18. Correlation between electrical and mechanical properties in La1-XSrXGa1-YMgYO3-¿ ceramics used as electrolytes for solid oxide fuel cells - Morales Comas, Miguel; Roa Rovira, Joan Josep; Pérez Falcón, José Manuel; Moure Arroyo, Alberto; Tartaj, Jesus; Espiell Álvarez, Ferran; Segarra Rubi, Merce
The relation between the electrical and the mechanical properties in Sr and Mg doped LaGaO3 ceramics, which can be used as electrolyte for solid oxide fuel cells, was investigated in terms of hardness and ionic conductivity. For this purpose, ceramic materials corresponding to the compositions of La1 xSrxGa1 yMgyO3 d (LSGM), with x ¼ 0.1 and y ¼ 0.2, and x ¼ 0.15 and y ¼ 0.2, were prepared. LSGM powders synthesized by the ethylene glycol complex solution method were shaped into disks by isostatic pressing method. The variation in the microstructure of samples was achieved by varying the sintering temperature between...

19. Deformation mechanism induced under high cycle fatigue test in a metaestable austenitic stainless steel - Roa Rovira, Joan Josep; Fargas Ribas, Gemma; Jiménez Piqué, Emilio; Mateo García, Antonio Manuel
Advanced techniques were used to study the deformation mechanisms induced by fatigue tests in a metastable austenitic stainless steel AISI 301LN. Observations by Atomic Force Microscopy were carried out to study the evolution of a pre-existing martensite platelet at increasing number of cycles. The sub-superficial deformation mechanisms of the austenitic grains were studied considering the cross-section microstructure obtained by Focused Ion Beam and analysed by Scanning Electron Microscopy and Transmission Electron Microscopy. The results revealed no deformation surrounding the pre-existing martensitic platelet during fatigue tests, only the growth on height was observed. Martensite formation was associated with shear bands on...

20. Contact damage and fracture micromechanism of multilayered TiN/CrN coatings at micro- and nano-length scales - Roa Rovira, Joan Josep; Jiménez Piqué, Emilio; Martínez, R; Ramírez Sandoval, Giselle; Tarragó, Josep Maria; Rodríguez, R; Llanes Pitarch, Luis Miguel
In this study, systematic nanomechanical andmicromechanical studies have been conducted in threemultilayer TiN/CrN systems with different bilayer periods (8, 19 and 25 nm). Additionally, experimental work has been performed on corresponding TiN and CrN single layers, for comparison purposes. The investigation includes the use of different indenter tip geometries aswell as contact loading conditions (i.e. indentation/scratch) such to induce different stress field and damage scenarioswithin the films. The surface and subsurface damage under the different indentation imprints and scratch tracks have been observed by atomic forcemicroscopy, field emission scanning electron microscopy and focused ion beam. Multilayer TiN/CrN coated systems are found to exhibit higher adhesion strength (under...

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