Sol-gel synthesis of 45S5 bioglass – Prosthetic coating by electrophoretic deposition

In this work, the 45S5 bioactive glass has been prepared by the sol-gel process using an organic acid catalyst instead of nitric acid usually used. The physico-chemical and structural characterizations confirmed and validated the elemental composition of the resulting glass. In addition, the 45S5 bioactive glass powder thus obtained was successfully used to elaborate by electrophoretic deposition a prosthetic coating on titanium alloy Ti6Al4V

Analyse couplée de paramètres mécaniques, physiologiques et respiratoires au cours de tests d'effort de longue durée sur ergocycle instrumenté

Le couplage entre mécanique du solide et physiologie respiratoire, est classiquement représenté par la relation linéaire entre puissance mécanique (P) et consommation d'oxygène (VO2). Nous avons investigué ces 2 paramètres, en caractérisant P par la puissance des efforts internes (PFint). PFint et VO2 sont étudiés séparément afin de rechercher l'information spécifique apportée par chacun de ces paramètres. L'analyse des données mécaniques et respiratoires, recueillies en simultané, montre la personnalisation de la stratégie motrice et de la stratégie respiratoire. Nous avons défini 2 types de couplage : en recherchant une relation linéaire associée au concept de rendement (or ce concept, qu'il soit associé à une notion énergétique ou d'efficacité, se révèle inopérant ) ; en étudiant séparément chaque paramètre mécanique ou physiologique comme la réponse, en asservissement et en régulation à une consigne en puissance (en mettant en regard ces résultats, cette méthode révèle des types de couplages inexplorés).POITIERS-BU Sciences (861942102) / SudocSudocFranceF

Sol-gel synthesis of 45S5 bioglass – Prosthetic coating by electrophoretic deposition

In this work, the 45S5 bioactive glass has been prepared by the sol-gel process using an organic acid catalyst instead of nitric acid usually used. The physico-chemical and structural characterizations confirmed and validated the elemental composition of the resulting glass. In addition, the 45S5 bioactive glass powder thus obtained was successfully used to elaborate by electrophoretic deposition a prosthetic coating on titanium alloy Ti6Al4V

Optimizing radiotherapy protocols using computer automata to model tumour cell death as a function of oxygen diffusion processes

International audienceThe concept of hypofractionation is gaining momentum in radiation oncology centres, enabled by recent advances in radiotherapy apparatus. The gain of efficacy of this innovative treatment must be defined. We present a computer model based on translational murine data for in silico testing and optimization of various radiotherapy protocols with respect to tumour resistance and the microenvironment heterogeneity. This model combines automata approaches with image processing algorithms to simulate the cellular response of tumours exposed to ionizing radiation, modelling the alteration of oxygen permeabilization in blood vessels against repeated doses, and introducing mitotic catastrophe (as opposed to arbitrary delayed cell-death) as a means of modelling radiation-induced cell death. Published data describing cell death in vitro as well as tumour oxygenation in vivo are used to inform parameters. Our model is validated by comparing simulations to in vivo data obtained from the radiation treatment of mice transplanted with human prostate tumours. We then predict the efficacy of untested hypofractionation protocols, hypothesizing that tumour control can be optimized by adjusting daily radiation dosage as a function of the degree of hypoxia in the tumour environment. Further biological refinement of this tool will permit the rapid development of more sophisticated strategies for radiotherapy

Electrophoretic Deposition of Bioactive Glass Coatings on Ti12Mo5Ta Alloy

International audienceTitanium alloys used in orthopedic surgery are usually coated with hydroxyapatite to improve their biocompatibility and osseointegration. Bioactive glasses (BGs) are an interesting alternative to hydroxyapatite for the production of prosthetic coatings due to their osteoproductive property (Class A bioactivity) and to their resorbability. However the classical techniques used to obtain prosthetic coatings are not suitable in the case of BGs. In this study bioactive glass coatings are obtained by electrophoretic deposition on a Ti12Mo5Ta alloy. These coatings were obtained from ethanol suspensions of two different bioglass powders: a Sol-Gel derived 58S and a Melting-Quenching derived 46S. Scanning electron microscopy observations were used to characterize the coatings (morphology and thickness) and the coating/substrate interfaces. The chemical composition of the coatings was studied by X-ray microanalysis and X-ray maps were performed to characterize the spatial distributions of all elements composing the coatings

Electrophoretic Deposition of Hydroxyapatite and 58S Bioactive Glass Coatings on the Ti6Al4V Alloy Subjected to Surface Mechanical Attrition Treatment

International audienceHydroxyapatite (HAP) and 58S Bioactive Glasses (BG) coatings are successfully synthesized by Electrophoretic Deposition (EPD) on Ti6Al4V alloy subjected to Surface Mechanical Attrition Treatment (SMAT). This process uses steel balls impacts on the Ti6Al4V surface to improve its mechanical properties. However when the Ti6Al4V substrate is treated by SMAT the industrial plasma spray technique is not efficient to obtain adherent HAP coatings. This problem is mainly related to the modifications of the Ti6Al4V surface topography due to the SMAT process. Therefore, in this work we demonstrate that EPD offers an efficient solution to solve this technical problem. Indeed we obtain a homogeneous and adherent HAP coating on the SMATed Ti6Al4V surface from a suspension of nanoparticles in ethanol. Moreover EPD is successfully employed to produce a 58S BG coating on the SMATed Ti6Al4V surface. Scanning Electron Microscopy (SEM) associated to Energy Dispersive X-Ray Spectroscopy (EDXS) reveals that the coatings obtained by EPD are adherent and compact without alteration of their chemical composition

Elaboration of monophasic and biphasic calcium phosphate coatings on Ti6Al4V substrate by pulsed electrodeposition current

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Electrophoretic Deposition of Hydroxyapatite and Bioactive Glasses coatings on the Ti6Al4V alloy subjected to Surface Mechanical Attrition Treatment

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Kapitza thermal resistance characterization of epitaxial graphene–SiC(0001) interface

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Unveiling the impact of embedding resins on the physicochemical traits of wood cell walls with subcellular functional probing

International audienceAs pressing needs for exploring molecular interactions in plants soar, conventional sample preparation methods come into question. Though resins used to embed plant tissues have long been assumed to bear no palpable effect on their properties, discrepancies in recent studies exploiting nanoscale microscopy suggest that their impact could be significant at small scales. By juxtaposing the traits of poplar sections prepared with and without embedding, we evaluate the diffusion (penetration depth) of acrylic and epoxy resins commonly used for embedding. Our results unveil critical quantitative differences when probing mechanical properties with a microscale nanoindentation indenter or a nanoscale tip. The latter resolves significant stiffness variations between the compound middle lamellae, the secondary cell wall layers S1 and S2, and the cell corner, not accessible with nanoindentation. Similar observations are drawn from comparing confocal Raman and nanoscale infrared spectroscopy. Our findings shed light on the effect of resin diffusion suggesting acrylic LR White to be the least diffusive for plant cell wall studies