Ti6Al4V-PEEK multi-material structures – design, fabrication and tribological characterization focused on orthopedic implants

Acknowledgements: This work was supported by FCT through the grants SFRH/BD/128657/2017 and SFRH/BPD/112111/2015, the project PTDC/EMSTEC/5422/2014 and also by project NORTE 01-0145_FEDER-000018. Additionally, this work was supported by FCT with the reference project UID/EEA/04436/2013, by FEDER funds through the COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) with the reference project POCI-01-0145-FEDER-006941.A multi-material concept that gathers Ti6Al4V and PEEK properties in a cellular structured component was designed, fabricated and investigated targeting hip implants. SLM and pressure assisted injection techniques were used to obtain Ti6Al4V-PEEK multi-material structures. Aiming to reproduce to some extension the tribological phenomena occurring during and after hip implant insertion, five tribological tests were outlined and performed. The obtained results showed that the presence of PEEK on the Ti6Al4V-PEEK cellular structures led to a substantial improvement on the wear resistance (62% reduction in the mass loss) when compared to the material currently available on market for hip implants. The multi-material solution here investigated shows a good compromise between the primary stability after implant insertion and the wear performance.info:eu-repo/semantics/publishedVersio

Ultra High Energy Tau Neutrinos and Fluorescence Detectors: A Phenomenological Approach

We investigate the possibility of detecting ultra-high energy cosmic tau-neutrinos by means of a process involving a double extensive air shower, the so-called Double-Bang Phenomenon. In this process a primary tau-neutrino interacts with an atmospheric quark creating a hadronic extensive air shower that contains a tau which subsequently decays creating a second extensive air shower. The number of these events strongly depends on the cross section and on the flux of ultra-high energy tau-neutrinos arriving at the Earth's atmosphere. We estimate the potential of optical detectors to observe Double-Bang events induced by tau-neutrinos with energies of about 1 EeV whose detection may confirm the maximal mixing observed in the atmospheric neutrinos also for ultra-high energy neutrinos, and give information on the neutrino flux and cross-section. For neutrino-nucleon Standard Model extrapolated cross-section and thick source model of flux (MPR), we estimate an event rate of 0.48/yr for an observatory with two fluorescence detectors with 90% efficiency in the neutrino energy range 0.5 < E_nu < 5 EeV.Comment: 17 pages, 6 eps figures, revtex 4, new calculation for the interaction probability end efficienc

6Li direct breakup lifetimes

alpha-d coincidence data were studied for the 6Li + 59Co reaction at E(lab) = 29.6 MeV. By using a kinematic analysis, it was possible to identify which process, leading to the same final state, has the major contribution for each of the selected angular regions. Contributions of the 6Li sequential and direct breakup to the incomplete fusion/transfer process were discussed by considering the lifetimes obtained by using a semiclassical approach, for both breakup components.Comment: 5 pages, 4 figures, Invited Talk (Parrallel Sessions) of A. Szanto de Toledo, prepared for the Proccedings of the 10th International Conference on Nucleus-Nucleus Collisions, August 16-21, 2009, Beijing, China; submitted to Nucl. Phys. A (Proceedings of NN2009

Study of 9Be+12C elastic scattering at energies near the Coulomb barrier

In this work, angular distribution measurements for the elastic channel were performed for the 9Be+12C reaction at the energies ELab=13.0, 14.5, 17.3, 19.0 and 21.0 MeV, near the Coulomb barrier. The data have been analyzed in the framework of the double folding S\~ao Paulo potential. The experimental elastic scattering angular distributions were well described by the optical potential at forward angles for all measured energies. However, for the three highest energies, an enhancement was observed for intermediate and backward angles. This can be explained by the elastic transfer mechanism. Keywords: 9Be+12C, Elastic Scattering, S\~aoo Paulo Potential

Exploring the reactivity of formylporphyrins with 3-(diethylamino)phenol. Synthesis, spectroscopic properties and singlet oxygen generation of a new porphyrin–rosamine conjugate

The design of novel molecular structures with tunable photophysical properties is an important research field for many applications including optoelectronics, sensing and bioimaging. Porphyrin and rhodamine/rosamine derivatives are among the most studied and relevant chemosensors and imaging probes due to their attractive photophysical properties, such as high absorption coefficients and long emission wavelengths. In this work, we present the synthesis and the structural characterization of a new porphyrin–rosamine conjugate H2P3 and its related triarylmethane precursors H2P1 and H2P2. The photophysical properties of H2P1, H2P2 and H2P3, and their ability to chelate iron(III) and copper(II) ions, were evaluated by absorption and emission spectroscopy. The formation of copper(II) complexes was confirmed by electron paramagnetic resonance (EPR), which also allowed the detection of an intense and stable radical signal for the free-base H2P3. Further studies involving the addition of the 2,2,6,6-tetramethylpiperidine spin trap to derivatives H2P1, H2P2 and H2P3, showed that only H2P3 gives rise to an EPR detectable signal due to a strong generation of singlet oxygen.publishe

Porphyrin-silica gel hybrids as effective and selective copper(II) adsorbents from industrial wastewater

Porphyrins are an important class of ligands with a tremendous ability to capture metal ions closely related to the rich coordination chemistry of porphyrins. Herein we use this characteristic to develop silica gel grafted derivatives for water remediation applications. Therefore, two porphyrin derivatives, one with three and the other with four mercaptopyridyl units were grafted on silica gel functionalized with 3-aminopropyltriethoxysilane. The new adsorbents Si3PyS and Si4PyS were characterized using a suitable set of techniques confirming the covalent attachment of the porphyrins to the silica surface. Additionally, microscopy and N2 adsorption analysis confirmed the structural integrity and preservation of the mesoporous structure of Si during surface modification. The results show that both hybrid materials exhibit good chemical and thermal stability and an outstanding Cu2+ removal capability, with a chemical adsorption capacity of 176.32 mg g–1 and 184.16 mg g–1, respectively. These materials have also been used in real water and industrial wastewater samples with minimal interference in their adsorption capabilities. Density Functional Theory calculations were performed to confirm the good performance of the hybrid materials Si3PyS and Si4PyS towards metal ions. The functionalization of silica surface with porphyrin-based ligands bearing additional binding motifs drastically improves the adsorption capability of the new hybrids towards metal ions. The presence of pyridyl units brings a meaningful advantage, since both porphyrin core and appended pyridyl groups are able of binding Cu2+ ions with high affinity, contributing to the enhancement of the chelating features of the adsorbents prepared when compared with other ligands supported in silica-based materials.publishe

Reaction mechanisms in the 6Li+59Co system

The reactions induced by the weakly bound 6Li projectile interacting with the intermediate mass target 59Co were investigated. Light charged particles singles and $\alpha$-$d$ coincidence measurements were performed at the near barrier energies E_lab = 17.4, 21.5, 25.5 and 29.6 MeV. The main contributions of the different competing mechanisms are discussed. A statistical model analysis, Continuum-Discretized Coupled-Channels calculations and two-body kinematics were used as tools to provide information to disentangle the main components of these mechanisms. A significant contribution of the direct breakup was observed through the difference between the experimental sequential breakup cross section and the CDCC prediction for the non-capture breakup cross section.Comment: 30 pages, 8 figure

Reaction mechanisms for weakly-bound, stable nuclei and unstable, halo nuclei on medium-mass targets

An experimental overview of reactions induced by the stable, but weakly-bound nuclei 6Li, 7Li and 9Be, and by the exotic, halo nuclei 6He, 8B, 11Be and 17F on medium-mass targets, such as 58Ni, 59Co or 64Zn, is presented. Existing data on elastic scattering, total reaction cross sections, fusion processes, breakup and transfer channels are discussed in the framework of a CDCC approach taking into account the breakup degree of freedom.Comment: 7 pages, 6 figures, Invited Talk given by C. Beck to the 10th International Conference on Nucleus-Nucleus Collisions, August 16-21, 2009 Beijing, China; Paper submitted to the NN2009 Proceedings, Nuclear Physics A (to be published

Manganese Defective Clustering: Influence on the Spectroscopic Features of Ceria-Based Nanomaterials

The influence of manganese modification on the spectroscopic features of manganese-doped CeO2 systems synthesized by the microwave-assisted hydrothermal route and their correlation with the presence of O defective structures were verified, focusing on their interaction with poisonous atmospheres. Raman and electron paramagnetic resonance studies confirmed the presence of defective clusters formed by dipoles and/or quadrupoles. The number of paramagnetic species was found to be inversely proportional to the doping concentration, resulting in an increase in the Mn2+ signal, likely due to the reduction of Mn3+ species after the interaction with CO. X-ray photoelectron spectroscopy data showed the pure system with 33% of its cerium species in the Ce3+ configuration, with an abrupt decrease to 19%, after the first modification with Mn, suggesting that 14% of the Ce3+ species are donating one electron to the Mn2+ ions, thus becoming nonparamagnetic Ce4+ species. On the contrary, 58% of the manganese species remain in the Mn2+ configuration with five unpaired electrons, corroborating the paramagnetic feature of the samples seen in the electron paramagnetic resonance study