Analysis of the Surface Integrity in Cryogenic Turning of Ti6Al4 v Produced by Direct Melting Laser Sintering

The Ti6Al4V is widely utilized in the biomedical field thanks to its high biocompatibility, however, due to its low machinability, is classified as a difficult-to-cut material. With the goal of improving the surface quality of biomedical components made of Ti6Al4V produced by the DMLS additive manufacturing technology and later on machined, Liquid Nitrogen was tested as a coolant in semi-finishing turning. The integrity of the machined surfaces is evaluated in terms of surface defects and topography as well as residual stresses. The obtained results showed that the cryogenic machining assured a lower amount of surface defects and higher values of the residual compressive stressed compared to dry cutting, but a general worsening of the surface topography was detected

Machinability of Ti6Al4V alloy produced by electron beam melting under different lubricating conditions

In the last decade, the growing diffusion of metal additive manufacturing technologies is revolutionising the manufacturing processes of the most advanced industrial fields. Nowadays, more and more companies operating in the aeronautic and in the biomedical field are employing the additive manufacturing technology of Electron Beam Melting (EBM) to produce prosthesis and aero engine parts made of the titanium alloy Ti6Al4V, traditionally produced by hot forging and machining. Thanks to this technology, it is possible to realise a complex shape component with tailored mechanical and geometrical properties, passing from the 3D CAD model directly to the near net shape geometry without any intermediate manufacturing steps, thus cutting the production costs. However, finishing machining operations are still necessary to remove the surface porosity that is a direct and inevitable consequence of additive manufacturing technologies, and to achieve higher surface quality and geometrical accuracy. Aiming to optimize the machining operation and to avoid detrimental surface damages left on the final product, the material machinability has to be taken into account. At the moment, many efforts coming from both the academic and industrial research have been spent to enhance the poor machinability of wrought Ti6Al4V alloy due to the increasing demand from the aeronautic field; however no published works and technical data are available regarding the machinability of EBM Ti6Al4V that presents different mechanical properties. Within the biomedical field, the surgical replacements made of Ti6Al4V are traditionally machined under flood coolants, made of synthetic or vegetable oil and water emulsions. As a consequence, costly sterilizing and cleaning operations are performed to remove the toxic and pollutant chemical residuals left on the finished products at the end of the manufacturing process. Thus, there is a need to revise the traditional lubricating strategies applied in machining operations of surgical implants, proposing an innovative solution that might satisfy technological, environmental and economic issues. In this PhD thesis, an innovative cryogenic cooling line has been developed and implemented to turn EBM Ti6Al4V alloy, as a promising alternative to standard cooling methods applied in machining surgical implants. The alloy machinability has been firstly investigated trough an experimental approach, evaluating the effects of three different cooling methods namely: dry, wet and cryogenic and of different cutting parameters, on the tool wear, on the surface integrity and on the chip morphology. Subsequently, a FE numerical model has been developed to simulate the turning operation of EBM Ti6Al4V alloy, capable to predict the effects of different process conditions. Due to the beneficial effects induced by the cryogenic cooling on the surface integrity of turned Ti6AL4V EBM test pieces, the feasibility of such technology for biomedical applications has been validated by means of wear tests: the wear resistance of cryogenically machined specimens clearly increased with a strong reduction of metallic particles loss. Finally, cryogenic turning has been employed to machine real acetabular cups, in comparison with standard cooling methods applied in machining surgical implants. The beneficial effects imparted by cryogenic cooling in terms of improved material machinability, improved wear resistance and satisfying achievable geometrical accuracy, foresee a potential applicability of this technology in the biomedical field for years to come

Aspectos da dicotomia, patrimonialização e despatrimonialização, à luz do novo direito civil e da responsabilidade civil

Orientador: Luis Edson FachinMonografia (graduação) - Universidade Federal do Paraná, Setor de Ciências Jurídicas, Curso de Graduação em Direit

Adversarial Hamiltonian learning of quantum dots in a minimal Kitaev chain

Determining Hamiltonian parameters from noisy experimental measurements is a key task for the control of experimental quantum systems. An experimental platform that recently emerged, and where knowledge of Hamiltonian parameters is crucial to fine-tune the system, is that of quantum dot-based Kitaev chains. In this work, we demonstrate an adversarial machine learning algorithm to determine the parameters of a quantum dot-based Kitaev chain. We train a convolutional conditional generative adversarial neural network (Conv-cGAN) with simulated differential conductance data and use the model to predict the parameters at which Majorana bound states are predicted to appear. In particular, the Conv-cGAN model facilitates a rapid, numerically efficient exploration of the phase diagram describing the transition between elastic co-tunneling and crossed Andreev reflection regimes. We verify the theoretical predictions of the model by applying it to experimentally measured conductance obtained from a minimal Kitaev chain consisting of two spin-polarized quantum dots coupled by a superconductor-semiconductor hybrid. Our model accurately predicts, with an average success probability of $97$\%, whether the measurement was taken in the elastic co-tunneling or crossed Andreev reflection-dominated regime. Our work constitutes a stepping stone towards fast, reliable parameter prediction for tuning quantum-dot systems into distinct Hamiltonian regimes. Ultimately, our results yield a strategy to support Kitaev chain tuning that is scalable to longer chains

Dental water jet efficacy in the plaque control of orthodontic patients wearing fixed appliance : a randomized controlled trial

Different studies assess the role of fixed orthodontic appliances in supragingival plaque accumulation. In patients wearing fixed orthodontic appliances a good management of oral hygiene is required in order to prevent complication like as decay, enamel demineralization, gingivitis, gingival hyperplasia and periodontitis. The aim of this Randomized Controlled Trial (RCT) is to evaluate the efficacy of the use of a DWJ in patients under orthodontic treatment with fixed multibracket appliance. The study design was single-blinded RCT with a split mouth protocol. Each patient followed a personal cleaning protocol using a DWJ in addition to traditional brushing only on one side while just brushing on the control side. The side on which was decided to use the DWJ was chosen randomly and the dental hygienist who took the measurements was blind. Plaque and gingival indexes were evaluated at baseline and at one, three and six-months follow-up. It did not emerge any difference in the plaque and gingival indexes trend between the two groups. Patients initially reported an worsening of the indexes at one month evaluation, then they set at baseline levels at three and six months. The dental water jet does not improve significantly the efficacy of home oral hygiene in orthodontic patients wearing a multi-bracket fixed appliance. Patients did not show the traditional worsening during the whole orthodontic therapy

Dal segno al suono. Indagine sulla lettura musicale allo strumento

"From sign to sound" is a research project aimed to investigate some peculiar features of the musical reading with reference to instrumental performance. Its purpose is to extend the present knowledge about cognitive, musical, and pedagogical aspects of the subject, pointing out problematic issues and solutions significant for the young musicians' music performance education. The main study profile, which differentiates it from very few existing international studies on the subject, arises from the particular situation of the Latin countries (to which some other Latin American countries must be added) that adopted, starting from XIX century, the syllabic designation of notes, abandoning the alphabetic one. The aim of the research was to clarify a) the extent to which the outlined situation is widespread in Italian and European instrumental teaching, b) what are the prevailing opinions about it, and c) whether different perspectives can be found based on instrumental families or educational schools.Published"Dal segno al suono" è un progetto di ricerca che indaga alcuni aspetti peculiari della lettura musicale riferiti specificamente all'esecuzione strumentale. Il suo scopo è ampliare le attuali conoscenze sugli aspetti cognitivi, musicali e pedagogici in materia, evidenziando problematiche e soluzioni significative per l'educazione all'esecuzione musicale dei giovani musicisti. Il profilo peculiare di questo studio, che lo differenzia da pochissimi studi internazionali esistenti sull'argomento, nasce dalla particolare situazione dei paesi latini (a cui vanno aggiunti alcuni paesi latinoamericani) che adottarono, a partire dal XIX secolo, la nominazione sillabica delle note, abbandonando quella alfabetica. Lo scopo della ricerca è stato quello di chiarire a) in che misura questa situazione si trova nella didattica strumentale italiana ed europea, b) quali sono le opinioni prevalenti in merito, e c) se si possono rintracciare prospettive diverse sulla base di famiglie strumentali o scuole pedagogiche differenti

Financial sustainability of the Beira-Rio arena: venue of the 2014 FIFA World Cup in Porto Alegre

The transformation of traditional football stadiums into multipurpose sports arenas is an international trend that was boosted in Brazil by the 2014 FIFA World Cup. The purpose of this study was to analyze the financial sustainability of the Beira-Rio arena, one of the venues of the event. Documents were analyzed, site visits were carried out and interviews were conducted with the managers. The results indicated that the Beira-Rio project includes eight sources of revenue: box office, VIP spaces, parking, advertising, shopping center, non-sporting events, catering and visitation to the facilities. Beira-Rio is currently in a process of transition between a traditional football stadium and a multipurpose sports arena. In 2017, it presented an approximate loss of R$8,08 million, not proving to be financially sustainable; however, it could become sustainable, with a profit of approximately R$ 38,51 million per year, if existing revenue sources are increased

Persistent and transient olfactory deficits in COVID-19 are associated to inflammation and zinc homeostasis

IntroductionThe Coronavirus Disease 2019 (COVID-19) is mainly a respiratory syndrome that can affect multiple organ systems, causing a variety of symptoms. Among the most common and characteristic symptoms are deficits in smell and taste perception, which may last for weeks/months after COVID-19 diagnosis owing to mechanisms that are not fully elucidated. MethodsIn order to identify the determinants of olfactory symptom persistence, we obtained olfactory mucosa (OM) from 21 subjects, grouped according to clinical criteria: i) with persistent olfactory symptoms; ii) with transient olfactory symptoms; iii) without olfactory symptoms; and iv) non-COVID-19 controls. Cells from the olfactory mucosa were harvested for transcriptome analyses. Results and discussionRNA-Seq assays showed that gene expression levels are altered for a long time after infection. The expression profile of micro RNAs appeared significantly altered after infection, but no relationship with olfactory symptoms was found. On the other hand, patients with persistent olfactory deficits displayed increased levels of expression of genes involved in the inflammatory response and zinc homeostasis, suggesting an association with persistent or transient olfactory deficits in individuals who experienced SARS-CoV-2 infection

Crossed Andreev reflection and elastic co-tunneling in a three-site Kitaev chain nanowire device

The formation of a topological superconducting phase in a quantum-dot-based Kitaev chain requires nearest neighbor crossed Andreev reflection and elastic co-tunneling. Here we report on a hybrid InSb nanowire in a three-site Kitaev chain geometry - the smallest system with well-defined bulk and edge - where two superconductor-semiconductor hybrids separate three quantum dots. We demonstrate pairwise crossed Andreev reflection and elastic co-tunneling between both pairs of neighboring dots and show sequential tunneling processes involving all three quantum dots. These results are the next step towards the realization of topological superconductivity in long Kitaev chain devices with many coupled quantum dots

Controlled crossed Andreev reflection and elastic co-tunneling mediated by Andreev bound states

A short superconducting segment can couple attached quantum dots via elastic co-tunneling (ECT) and crossed Andreev reflection (CAR). Such coupled quantum dots can host Majorana bound states provided that the ratio between CAR and ECT can be controlled. Metallic superconductors have so far been shown to mediate such tunneling phenomena, albeit with limited tunability. Here we show that Andreev bound states formed in semiconductor-superconductor heterostructures can mediate CAR and ECT over mesoscopic length scales. Andreev bound states possess both an electron and a hole component, giving rise to an intricate interference phenomenon that allows us to tune the ratio between CAR and ECT deterministically. We further show that the combination of intrinsic spin-orbit coupling in InSb nanowires and an applied magnetic field provides another efficient knob to tune the ratio between ECT and CAR and optimize the amount of coupling between neighboring quantum dots