Informe JBC. REF 357

Estudio del espesor y composición química de los baños realizados en tres puntas de soldaduras.Preprin

Electrodeposición de recubrimientos de fosfato de calcio sobre titanio

El titanio y sus aleaciones son biomateriales usados frecuentemente en implantes y prótesis. Sin embargo, estos biomateriales metálicos tienen limitaciones relacionadas con la bioactividad.Una vía para aumentar la bioactividad del titanio es añadir un recubrimiento de fosfato de calcio (CaP) a la superficie mediante deposición electroquímica. Esta técnica tiene como ventajas la baja temperatura del proceso y un buen control del espesor y la composición química de la capa depositada. Durante el proceso, sin embargo, se producen burbujas de hidrógeno en las proximidades del cátodo, que dificultan la obtención de capas uniformes.El presente estudio propone usar corriente pulsada para la electrodeposición como mecanismo para reducir la producción de burbujas de hidrógeno y mejorar el equilibrio de la concentración de iones en la solución, permitiendo la formación de capas de fosfato de calcio más uniformes.Peer Reviewe

A genetic algorithm optimized fractal model to predict the constriction resistance from surface roughness measurements

The electrical contact resistance greatly influences the thermal behavior of substation connectors and other electrical equipment. During the design stage of such electrical devices, it is essential to accurately predict the contact resistance to achieve an optimal thermal behavior, thus ensuring contact stability and extended service life. This paper develops a genetic algorithm (GA) approach to determine the optimal values of the parameters of a fractal model of rough surfaces to accurately predict the measured value of the surface roughness. This GA-optimized fractal model provides an accurate prediction of the contact resistance when the electrical and mechanical properties of the contacting materials, surface roughness, contact pressure, and apparent area of contact are known. Experimental results corroborate the usefulness and accuracy of the proposed approach. Although the proposed model has been validated for substation connectors, it can also be applied in the design stage of many other electrical equipments.Postprint (author's final draft

Titanium scaffolds fabricated by Direct Ink Writing and functionalized with dual-action coatings with osteoinductive and antibacterial properties

The stress shielding, a result of the stiffness mismatch between titanium and bone, the lack of bioactivity and the infections are the main cause of the implants failure. In this work, porous titanium structures (between 50 and 70%) were produced by direct ink writing, using a new Ti ink formulation. A water and thermal treatment was optimized to ensure the complete elimination of the binder before the sintering process. The samples were sintered in high vacuum at 1150 ºC.The stiffness and compressive strength were similar to those of cancellous bone. The functionalization of the scaffold surface with a thermochemical treatment that incorporates Ga ions resulted in Ga-containing calcium titanate layer that generate homogeneous apatite layer in simulated body fluid. The Ga3+ release promote the antibacterial effect against gram positive strains. SaOS-2 cells adhered and proliferated on the Ga-doped Ti surfaces; its presence contributes to cell differentiation and increases the mineralization. © European Powder Metallurgy Association (EPMA)Postprint (published version

Antibacterial PHAs coating for titanium implants

Biomaterial-associated infection is a serious complication of modern implantation surgery. Thus, the improvement of implant surfaces is required to avoid the first stage for biofilm formation, bacterial adhesion. The current research addresses this issue by developing drug delivery systems (DDS) consisting of antibiotic-loaded polyhydroxyalkanoates (PHAs) coatings on titanium implants. Dip-coating technique was used to achieve optimal coatings with biodegradable biopolyesters, polyhydroxybutyrate (PHB) and its copolymer, polyhydroxybutyrate-co-hydroxyvalerate (PHBV). The coatings were completely characterized (wettability, topography, thickness and roughness), and studies of drug delivery, toxicity, antibacterial effect, and cell adhesion were performed. For both of biopolymers, surfaces were partially covered with 1 and 3 immersions, while with 6, they were completely covered. Although both antibiotic-loaded biopolymer coatings assure the protection against bacteria populations, PHBV coatings are closer to the desired release profile; its faster degradation provides for a greater and more stable drug release for a given period of time compared to PHB coatings. The use of coatings with different drug concentration per layer results in more controlled and homogeneous releases. The DDS designed not only assure to avoid the first stage of bacterial adhesion, but also their proliferation and biofilm formation, since the coatings degrade with time under physiological conditions, guaranteeing a prolonged drug release.Preprin

Treball de selecció de materials

L’objectiu principal de l’activitat és desenvolupar l’aprenentatge autònom mitjançant el desenvolupament d’un treball en grup relacionat amb l’àmbit dels materials

Antimicrobial PHAs coatings for solid and porous tantalum implants

Biomaterial-associated infections (BAI) are the major cause of failure of indwelling medical devices. The risk of BAI can end dramatically in the surgical removal of the affected device. Therefore, a major effort must be undertaken to guarantee the permanence of the implant. In this regard, we have developed antimicrobial coatings for tantalum (Ta) implants, using polyhydroxyalkanoates (PHAs) as matrices for carrying an active principle. The dip-coating technique was successfully used for covering solid Ta discs. An original PHA emulsion flow process was developed for the coating of porous Ta structures, specially for the inner surfaces. The complete characterization of the biopolymer coatings, their antibacterial properties, toxicity and biointegration were analyzed. Thus, non-toxic, well-biointegrated homogeneous biopolymer coatings were attained, which showed antibacterial properties. By using biodegradable PHAs, the resulting drug delivery system assured the protection of Ta against bacterial infections for a period of time.Peer ReviewedPostprint (author's final draft

Resolución de problemas de materiales como herramienta de aprendizaje autónomo

El principal objetivo de la actividad es proporcionar herramientas al alumnado para consolidar los conocimientos teóricos adquiridos en el ámbito de los materiales, mediante aprendizaje autónomo basado en la resolución de ejercicios prácticos

Bateries de qüestions bàsiques de materials

Fomentar l’estudi i l’aprenentatge autònom de continguts bàsics de les assignatures troncals de materials (Fonaments de Ciència dels Materials, Tecnologia dels Materials i Materials Aeroespacials), de les titulacions d’Enginyeria Industrial i Enginyeria Aeronàutica