Bacterias y su implicación en el fallo de implantes de Titanio

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Anodización del titanio para la mejora ante la degración química de material quirúrgico.

The titanium alloys used in orthopaedic and dental implants are corrosion-resistant and compatible with the human body due to the titanium oxid film which forms spontaneously on the implant surface. However, the utilization of more than one type of alloy or metal on the same patient and the fragility and the thin thickness of the oxid layer, can give rise to the appearance of the corossion phenomena and/or ion release. It is well known that enough concentration of metallic particles are toxic, and are able to produce lnflammation, allergy genetic mutations or carcinogenic processes. With the purpose of minimize the corrossion in the implants and the metallic ion release to the physiological environment it is possible to grow up the titanium oxid layer in a controlled way to have a tough, homogeneous and stable layer with the anodization technique. In this work it is evaluated the improvements in corrosion resistance and the decrease of the metallic ion release due to the anodized layer

Anodización del titanio para la mejora ante la degradación química de material quirúrgico

The titanium alloys used in orthopaedic and dental implants are corrosion-resistant and compatible with the human body due to the titanium oxid film which forms spontaneously on the implant surface. However, the utilization of more than one type of alloy or metal on the same patient and the fragility and the thin thickness of the oxid layer, can give rise to the appearance of the corossion phenomena and/or ion release. It is well known that enough concentration of metallic particles are toxic, and are able to produce lnflammation, allergy genetic mutations or carcinogenic processes. With the purpose of minimize the corrossion in the implants and the metallic ion release to the physiological environment it is possible to grow up the titanium oxid layer in a controlled way to have a tough, homogeneous and stable layer with the anodization technique. In this work it is evaluated the improvements in corrosion resistance and the decrease of the metallic ion release due to the anodized layer

Unión de péptidos a superficies de titanio para la mejora de la osteointegración

El presente estudio pretende mejorar el proceso de osteointegración del implante de titanio mediante la biofuncionalización de su superficie. Para ello se ha realizado una previa silanización de la superficie y una posterior unión covalente entre el silano y un péptido el cual posee la secuencia RGD. Se han estudiado diferentes aspectos como es la estabilidad tanto de conjunto titanio-silano como silano-péptido. Finalmente se ha realizado un ensayo de adhesión celular utilizando células osteoblásticas MG63 cuyas muestras de titanio han sido previamente biofuncionalizadas con el proceso estudiado.This study aims to improve the osseointegration process of the titanium implant through surface biofunctionalization. Samples were silanised on the surface and afterwards a peptide with the RGD sequence was covalently attached to the silane. Specific characteristics of the stability of the union titanium-silane as well as silane-peptide were studied. Finally cell adhesion studies to samples biofunctionalized with the technique studied in this work were made with MG63 osteoblastic cells.Peer Reviewe

Modelo de la lubricación hidrodinámica de la articulación de una prótesis de cadera

En este trabajo se estiman las presiones a la cual está sometida la articulación de la cadera por los líquidos fisiológicos, esta aproximación se ha realizado basado en las eciaciones de mecánica de fluidos y considerando la geometría de la prótesis de cadera. Estos datos son de gran importancia para el diseño de nuevas prótesis de cadera y para mejorar la resistencia al desgaste entre la prótesis y el acetábulo. Una vez obtenida la ecuación - modelo de lubricación articular, se han obtenido valores para un caso general de presiones de alrededor de los 120 KP

A further experimental step in the analysis of hierarchical responding

This study is a step forward in the difficult task of analyzing the transformation of functions via hierarchical relations. Eight participants underwent a computer task with five phases. During Phase 1, four stimuli were trained to become the following relational cues: INCLUDES, BELONGS TO, SAME, and DIFFERENT. In Phase 2, three equivalence classes were trained and tested (A1-B1-C1-D1; A2-B2-C2-D2; A3-B3-C3-D3). During Phase 3, inclusion relations were first established, by using the INCLUDES and BELONGS TO relational cues, between the to-be lower levels of the hierarchy, namely A1/B1, A2/B2, and A3/B3; and stimuli X.1, X.2, and Y.1, respectively. Then, the INCLUDES relational cue was used to establish inclusion relations between X.1/X.2 and X, and between Y.1 and Y, so that X and Y would become the most inclusive levels of two separate hierarchical networks. In Phase 4, X.1 was established as cold, D2 as heavy, and C3 as sweet. Lastly, in Phase 5 (Critical Test), seven stimuli from both hierarchical networks were tested for the transformation of functions. Five of the six participants who made it to this test responded correctly. Implications, limitations, and further research are discussed

Dynamic response of periodic infinite structure to arbitrary moving load based on the Finite Element Method

[EN] A common problem in railway engineering is the dynamic of repetitive structures subject to moving loads. Bridges, rails or catenaries are the most representative periodic structures, over which the train acts as a moving exciter. Usually, these structures are long enough to consider that their dynamic response is in permanent regime. To assume the steady-state regime some features have to be considered: infinite length structure, perfect periodicity and constant velocity of the moving load. This paper adopts these assumptions and provides the steady-state solution of a generic periodic structure subject to an arbitrary and also periodic moving load. The structure is divided into repetitive blocks modelled by the Finite Element Method. By applying the periodicity condition it is possible to consider the entire structure dynamics with only one block. The problem is stated in the frequency domain and moved back to time domain by means of Discrete Fourier Transform.The authors would like to acknowledge the financial support received from the Spanish Ministry of Economy, Industry and Competitiveness (TRA2017-84736-R).Gil-Romero, J.; Gregori, S.; Tur, M.; Fuenmayor, F. (2022). Dynamic response of periodic infinite structure to arbitrary moving load based on the Finite Element Method. En Proceedings of the YIC 2021 - VI ECCOMAS Young Investigators Conference. Editorial Universitat Politècnica de València. 326-333. https://doi.org/10.4995/YIC2021.2021.12606OCS32633

Estudio de la biocompatibilidad de una nueva aleación beta-titanio de bajo módulo de elasticidad

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Optimization of a new Ni-free Ti alloy for applications in the implant field

Three new Ni-free Ti alloys, Ti-16.2Hf-24.8Nb-1Zr, Ti-5.2Hf-31.2Nb-0.4Zr and Ti-16Hf-36.2Nb-1Zr (wt%), were designed and produced in order to obtain shape memory and/or low elastic modulus materials in order to avoid stress shielding and to enhance bone regeneration in the load transfer implant field. The alloys were microstructurally and mechanically characterized, cytotoxicity was evaluated using MG63 osteoblast-like cells. The elastic modulus of the new alloys (between 67-90 GPa) are smaller than those of the commercial alloys employed for implantation. The lowest elastic modulus alloy, Ti-16.2Hf-24.8Nb-1Zr (wt %), with 67.5 GPa, was optimized by cold work in order to determine the key factor that promotes the desired shape memory properties and/or low elastic modulus. A higher proportion of martensite was observed by optical and electron transmission microscopy in the low cold work samples compared to the quenched alloy. The elastic modulus for each cold work condition was evaluated by nanoindentation tests using a spherical tip. The elastic modulus decreases when increasing the cold work level. The lowest value corresponds to the 99% cold work condition, with 44 GPa, closer to that of cortical bone and smaller than the quenched alloy (67.5 GPa).Tres nuevas aleaciones de Ti libres de Ni, Ti-16.2Hf-24.8Nb-1Zr, Ti-5.2Hf-31.2Nb-0.4Zr y Ti-16Hf-36.2Nb-1Zr, porcentajes en peso, fueron diseñadas y fabricadas con el fin de obtener memoria de forma y/o bajo módulo elástico con el objetivo de evitar el apantallamiento de cargas y mejorar la regeneración ósea en el campo de la implantología de transferencia de carga. Las aleaciones fueron caracterizadas microestructural y mecánicamente y la citotoxicidad fue evaluada utilizando osteoblastos MG63. El módulo elástico de las nuevas aleaciones (entre 67-90 GPa) es menor que el de las aleaciones comerciales utilizadas en implantología. El menor módulo elástico corresponde a la aleación Ti-16.2Hf-24.8Nb-1Zr, con 67.5 GPa y fue optimizado mediante trabajo en frío con el objetivo de determinar el factor responsable de la obtención de las propiedades deseadas de bajo módulo elástico y/o memoria de forma. Una mayor proporción de martensita fue observada por microscopía óptica y microscopía electrónica de transmisión en las muestras con bajo porcentaje de trabajo en frío en comparación con la muestra templada. El módulo elástico correspondiente a cada condición de trabajo en frío fue evaluado mediante nanoindentación con punta esférica. El módulo elástico disminuye al aumentar el porcentaje de trabajo en frío. El menor valor corresponde a la condición de 95% de trabajo en frío, con 44 GPa, valor cercano al del hueso cortical y menor que el del material templado (67.5 GPa).Peer Reviewe