Design of a nitrogen-implanted titanium-based superelastic alloy with optimized properties for biomedical applications

International audienceIn this study, a superelastic Ni-free Ti-based biomedical alloy was treated in surface by the implantation of nitrogen ions for the first time. The N-implanted surface was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and secondary ion mass spectroscopy, and the superficial mechanical properties were evaluated by nano-indentation and by ball-on-disk tribological tests. To investigate the biocompatibility, the corrosion resistance of the N-implanted Ti alloy was evaluated in simulated body fluids (SBF) complemented by in-vitro cytocompatibility tests on human fetal osteoblasts. After implantation, surface analysis methods revealed the formation of a titanium-based nitride on the substrate surface. Consequently, an increase in superficial hardness and a significant reduction of friction coefficient were observed compared to the non-implanted sample. Also, a better corrosion resistance and a significant decrease in ion release rates have been obtained. Cell culture experiments indicated that the cytocompatibility of the N-implanted Ti alloy was superior to that of the corresponding non-treated sample. Thus, this new functional N-implanted titanium-based superelastic alloy presents the optimized properties that are required for various medical devices: superelasticity, high superficial mechanical properties, high corrosion resistance and excellent cytocompatibility

Corrosion resistance of the new Ti-25Ta-25Nb alloy in severe functional conditions

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Synthesis and characterization of a new superelastic Ti-25Ta-25Nb biomedical alloy

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Long-term corrosion performances and cytocompatibility of nitrided Ti and Ti-6Al-4V alloy in severe functional conditions

International audienceIn the present work, nitrogen ion implantation (original method) to enhance the corrosion performance and cytocompatibility of biomedical pure titanium (CP Ti) and Ti-6Al-4V alloy has been studied. Different characterization methods were used to investigate the corrosion resistance of the nitrided Ti and Ti-6Al-4V samples such as anodic polarization, electrochemical impedance spectroscopy, monitoring of the open circuit potentials and corresponding gradients, evaluation of corrosion rates. Further, cell viability, initial cell spreading and osteoblast proliferation were tested in order to assess cytocompatibility of modified Ti and Ti-6Al-4V alloy. In severe functional conditions, the main electrochemical parameters for nitrided biomaterials presented better values, revealing nobler behaviour than un-nitrided samples; these more favourable values assure a very good corrosion resistance for long term of the treated biomaterials. The results of biological performance evaluation indicated that nitrided Ti and Ti-6Al-4V represent suitable biomaterials for the adhesion and proliferation of human osteoblasts in vitro. All these findings demonstrate that nitrided biomaterials exhibited a very good improvement of their corrosion resistance and biocompatibility, characteristics which recommend them as potential candidates for bone implants

Surface characterization and biocompatibility of titanium alloys implanted with nitrogen by Hardion+ technology

International audienceIn this study, the new Hardion+ micro-implanter technology was used to modify surface properties of biomedical pure titanium (CP-Ti) and Ti-6Al-4V ELI alloy by implantation of nitrogen ions. This process is based on the use of an electron cyclotron resonance ion source to produce a multienergetic ion beam from multicharged ions. After implantation, surface analysis methods revealed the formation of titanium nitride (TiN) on the substrate surfaces. An increase in superficial hardness and a significant reduction of friction coefficient were observed for both materials when compared to non-implanted samples. Better corrosion resistance and a significant decrease in ion release rates were observed for N-implanted biomaterials due to the formation of the protective TiN layer on their surfaces. In vitro tests performed on human fetal osteoblasts indicated that the cytocompatibility of N-implanted CP-Ti and Ti-6Al-4V alloy was enhanced in comparison to that of the corresponding non treated samples. Consequently, Hardion+ implantation technique can provide titanium alloys with better qualities in terms of corrosion resistance, cell proliferation, adhesion and viability

Rising the sharpening of digital image by virtue of filtering the object shadow pixels

Во многих приложениях, связанных с анализом цифровых изображений, объекты на снимке могут иметь невысокий уровень контраста по отношению к фону, на котором они расположены. Для повышения резкости таких изображений в статье разрабатываются методы идентификации, и фильтрации пикселей тени, предназначенные для устранения перепадов яркости между объектом и фоном.У багатьох додатках, пов'язаних з аналізом цифрових зображень, об'єкти на знімку можуть мати невисокий рівень контрасту по відношенню до фону, на якому вони розташовані. Для підвищення різкості таких зображень у статті розробляються методи ідентифікації та фільтрації пікселей тіні, призначені для усунення перепадів яскравості між об'єктом і фоном.In various applications pertaining to analysis of digital images the image objects may have a low contrast level relative to the underlying background. In order to increase the sharpness of such images, in this article the methods are proposed for identification and filtering of shadow pixels being intended for elimination of the object-background brightness jumps