1,720,979 research outputs found
In vitro corrosion characterization and cell proliferation on surface-modified Ti
No full textTwo types of surface treatments (Low pressure metal organic chemical vapor deposition (Ti-MOCVD) and anodized Ti) have been conducted on Ti to improve their osteointegration properties in view of dental implant application. The two typologies of surfaces have been characterized in vitro both regarding the corrosion and the in biological behaviour in comparison with the Ti machined surface. The corrosion tests showed that both the surface treatments reduced markedly the corrosion rate compared to Ti machined. The biological tests showed that all specimens are cytocompatible and significant differences among them were detected. In particular WST1 tests showed more viable osteoblasts adhering to MOCVD specimens in comparison with the other surfaces
In vitro corrosion study by EIS of a nickel-free stainless steel for orthopaedic applications.
No full textLocalized corrosion of orthodontic wires: Test methods and experimental characterization
No full textPlasma Electrolytic Oxidation (PEO) layers from silicate/phosphate baths on Ti-6Al-4V for biomedical components: Influence of deposition conditions and surface finishing on dry sliding behaviour
Full text linkPlasma Electrolytic Oxidation (PEO) layers were produced on Ti-6Al-4V in different conditions, so as to assess the influence of layer structure, current mode, duty cycle and surface finishing on microstructural features and tribological behavior. In DC regime, the double-layer structure (silicate bath followed by phosphate bath) beneficially affected wear resistance. In unipolar pulsed DC (phosphate bath), the wear resistance of single layers improved with increasing duty cycle, due to improved microstructure and adhesion: high duty cycle single layers can be considered an alternative to double-layer deposition. Surface finishing by abrasive blasting with spheroidal glass beads leads to surface roughness decrease and hence to decreased friction and improved wear resistance. The best-performing PEO layers showed promising results in the comparison with reference materials such as CoCrMo (both uncoated and (Ti,Nb)N PVD-coated) and PVD-coated Ti-6Al-4V up to 30 N normal load
Procedimento di trattamento della superficie di un impianto dentale, in particolare in titanio e impianto ottenuto con il procedimento
No full text
Trattamenti superficiali su leghe d’interesse ortopedico/Surface treatments on orthopaedic alloys
No full textLe protesi articolari e i dispositivi per il fissaggio osseo sono realizzati quasi esclusivamente in lega Ti6Al4V e lega CoCrMo in virtù della loro inerzia chimica in ambiente fisiologico. Queste caratteristiche sono però insufficienti a garantire il successo dell’impianto se non accompagnate da un comportamento tribologico adeguato alla funzione del dispositivo. Per migliorare le proprietà superficiali di entrambe le leghe sono stati proposti rivestimenti PVD in TiNbN su substrati in CoCrMo. Tali coating si sono dimostrati efficienti barriere al rilascio di ioni ma devono essere post-lucidati per mantenere il basso coefficiente di attrito verso il polietilene. Trattamenti di ossidazione PEO su substrati in Ti6Al4V si sono dimostrati promettenti alternative ai film sottili PVD, sia come barriera al rilascio di ioni, sia come miglioramento delle proprietà tribologiche del substrato.Articular replacements and trauma medical devices are mainly made of Ti6Al4V and CoCrMo alloys due to their chemical inertness in body environment. However, this characteristic is not sufficient to guarantee good implant performance if no adequate tribological resistance is also present. In order to increase the surface properties of both materials different surface treatment have been proposed. TiNbNPVD on CoCrMo has shown to be an effective barrier against ion release from the substrate, however it needs a final polishing treatment in order to maintain its low friction coefficient against polyethylene. PEO oxidation treatment on Ti6Al4V showed to be good alternatives to PVD thin films, both as ion release barrier and enhancing tribological substrate properties
In vitro corrosion study by EIS of an equiatomic NiTi alloy and an implant quality AISI 316 stainless steel
No full textThe electrochemical impedance spectroscopy (EIS) technique was used for the
study of the electrochemical behavior of an equiatomic NiTi alloy and an implant quality AISI
316 stainless steel type ASTM F138. Experiments were carried out using four different
different test solutions: phosphate buffered saline (PBS), Dulbecco minimum essential medium
(MEM), MEM fetal calf serum (FCS), and MEM fetal calf serum fibroblast cell
(CELL). Specimens were finished to 600-grit SiC paper and were tested in conditions that did
not provoke abrupt mechanical damage of the passive film. Bode-phase spectra showed the
presence of two maxima and were fitted with an equivalent circuit characterized by two
parallel combinations (R, resistance; CPE, constant phase element). The R1 and CPE1 branch
was assigned to the inner compact passive film and the R2 and CPE2 branch to the external
porous film. The resistance of the inner film R1, roughly corresponding to the polarization
resistance (Rp), which is inversely proportional to the material’s corrosion rate, increased with
the immersion time and was generally greater in PBS than in other media. With the exception
of FCS solution, R1 for NiTi alloy is better or similar to that of ASTM F13
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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