228 research outputs found
Pulsed Current Effect on the Hard Anodizing of an AlSi10Mg Aluminum Alloy Obtained via Additive Manufacturing
The hard anodizing treatments of cast Al-Si alloys are notoriously difficult. Indeed, their microstructural features hinder the growth of a uniform, compact, and defect-free anodic oxide. In this paper, AlSi10Mg samples, produced via Gravity Casting (GC) and Additive Manufacturing, i.e., Laser Powder Bed Fusion (L-PBF), were hard anodized in a sulfuric acid bath, in order to verify how the particular microstructure obtained via L-PBF affects the thickness, hardness, compactness, and defectiveness of the anodic oxide. Moreover, for the first time, Pulsed Direct Current (PDC) procedures were used to perform the hard anodizing treatments on additively manufactured AlSi10Mg alloy. Several combinations of temperature and electrical parameters, i.e., current density, frequency, and Duty Cycle, were tested. The anodized samples were characterized through optical microscopy analysis, Scanning Electron Microscopy (SEM) analysis, and accelerated corrosion tests, i.e., Potentiodynamic Polarization (POL) and Electrochemical Impedance Spectroscopy (EIS) measurements. The PDC procedures allowed improvement of the compromise between evenness, compactness, and defectiveness. Among the attempted PDC procedures, a specific combination of electrical parameters and temperature allowed the best results to be obtained, i.e., the highest hardness and the lowest volumetric expansion values without compromising the oxide quality rating and the corrosion resistance behavior. However, none of the attempted PCD strategies allowed the hardness values obtained on samples produced via GC to be reached
Total Knee Arthroplasty for Post-Traumatic Proximal Tibial Bone Defect: Three Cases Report
Bone stock deficiency in primary as well as in revision total knee arthroplasty (TKA) represents a difficult problem to surgeon with regard to maintaining proper alignment of the implant components and in establishing a stable bone-implant interface. Different surgical procedures are available in these situations, for instances the use of bone cement, prosthetic augments, custom implant, and wire mesh with morsellized bone grafting and structural bone allograft. Structural allograft offers a numerous advantages as easy remodeling and felling cavitary or segmental defects, excellent biocompatibility, bone stock restoration and potential for ligamentous reattachment. In this article we report a short term result of three cases affected by severe segmental medial post/traumatic tibial plateau defect in arthritic knee, for which massive structural allograft reconstruction and primary total knee replacement were carried. The heights of the bone defect were between 27-33 mm and with moderate medio-lateral knee instability. Pre-operative AKS score in three cases was 30, 34 and 51 points consecutively and improved at the last follow-up to 83, 78 and 85 consecutively. No acute or chronic complication was observed. Last radiological exam referred no signs of prosthetic loosening, no secondary resorption of bone graft and well integrated graft to host bone. These results achieved in our similar three cases have confirmed that the structural bone allograft is a successful biological material to restore hemi-condylar segmental tibial bone defect when total knee replacement is indicated
The Italian Consensus Conference on FAI Syndrome in Athletes (Cotignola Agreement)
Background. Femoro-acetabular impingement (FAI) is an important topic in literature because of its strong relationship with sport populations. Methods. Sixty-five experts participated in "this Consensus Conference (CC)". They discussed, voted and approved a consensus document on the FAI syndrome in athletes. Results. The CC experts approved document provided suggestions concerning: 1) Epidemiology of FAI; 2) Clinical evaluation; 3) Radiological evaluation; 4) Conserva-tive treatment; 5) Surgical criteria; 6) Surgical techniques; 7) Post-surgical rehabilita-tion; 8) Outcome evaluation; 9) FAI-associated clinical frameworks. Conclusions. The CC offers a multidisciplinary approach to the diagnosis and treat-ment of FAI syndrome in athletes taking into account all the different steps needed to approach this pathology in sport populations
Young tourists’ experiences at dark tourism sites: Towards a conceptual framework
While dark tourism aimed at adults reminds them of past tragic fights, faults and follies, thousands of children and youth also consume inherent memorial messages at dark tourism sites. This paper addresses these unnoticed childhood encounters, about which scholarly discourse remains conspicuously silent. At present, dark tourism research focuses almost exclusively on adults and does not adequately explain young tourists’ experiences. How children experience dark tourism sites has much to do with their understanding of death. Because younger children may not possess an adult-like knowledge of death, they are unable to experience a site as dark. Other theoretical disparities include children’s limited agency in choosing their destinations and their unique and often playful exploration of dark places. To address the inadequacy of current dark tourism conceptualisations, we propose a new framework to encourage scholarly interrogation of children’s experiences at dark tourism sites. Drawing from multiple sources including archival studies and original research with youth, we offer a rationale for considering four major, intersecting influences on a young tourist’s experience: understanding of death, visit preparation (at home or in school), site and interpretation features and dynamics of the specific visit (e.g. group membership, norms and itinerary). Ultimately, this paper uncovers potential research avenues to bring children’s perspectives and experiences to the core of dark tourism research
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