Additive manufacturing of NiTi-Ti6Al4V multi-material cellular structures targeting orthopedic implants

The amount of hip revision surgeries is significantly increasing due to the loss of fixation between implant and bone, that leads to implant failure. The stiffness mismatch between Ti6Al4V hip implants and bone tissue, the non-uniform implant-bone contact pressure, and the poor wear resistance of Ti6Al4V are pointed as three critical issues that contribute to these implant's failure. In this study, a multi-material design and fabrication concept was exploited aiming to change traditional manufacturing paradigms, by allocating different biomaterials in a single component targeting a multi-functional hip implant. Selective Laser Melting technology was explored to fabricate NiTi-Ti6Al4V multi-material cellular structures with a Ti6Al4V inner region and a NiTi outer region. This work was focused on the SLM fabrication and processing parameters validation on a commercial SLM equipment. The morphological analyses allowed to assess a successful solidification and bond between NiTi and Ti6Al4V materials in the transition region. The shear tests revealed a high bond strength of the transition region with an average strength of 33 MPa. The nano-indentation results showed that the Ti6Al4V region exhibits a higher hardness and elastic modulus when compared with the NiTi region. This work is a part of a broader objective that aims to create a NiTi-Ti6Al4V multi-material and cellular structured hip implant capable to provide customized stiffness, superior wear resistance and a controlled NiTi outer region volume change.This work was supported by FCT (Fundação para a Ciência e a Tecnologia) through the grant SFRH/BD/128657/2017 and the projects PTDC/EMS-TEC/5422/2014_ADAPTPROSTHESIS and UID/EEA/04436/2019

The determination of drag in the gliding phase in swimming

The hydrodynamic drag forces produced by the swimmer during the sub aquatic gliding have been analyzed appealing to experimental investigation methods (e.g., Lyttle et al., 2000). However, the obtained results varied, which can translate some of the main inherent difficulties involved in the experimental studies. Thus, through application of a numerical method of Computational Fluid Dynamics (CFD), we intended to study the hydrodynamic drag forces, created during the displacement of the swimmer in different gliding positions, attempting to address some practical concerns to swimmers and coaches

Engineering the elastic modulus of NiTi cellular structures fabricated by selective laser melting

Nickel-titanium (NiTi) cellular structures are a very promising solution to some issues related to orthopaedic implant failure. These structures can be designed and fabricated to simultaneously address a combination of mechanical and physical properties, such as elastic modulus, porosity, wear and corrosion resistance, biocompatibility and appropriate biological environment. This ability can enhance the modest interaction currently existing between metallic dense implants and surrounding bone tissue, allowing long-term successful orthopaedic implants. For that purpose, NiTi cellular structures with different levels of porosity intended to reduce the elastic modulus were designed, modelled, selective laser melting (SLM) fabricated and characterized. Significant differences were found between the CAD design and the SLM-produced NiTi structures by performing systematic image analysis. This work proposes designing guidelines to anticipate and correct the systematic differences between CAD and produced structures. Compressive tests were carried out to estimate the elastic modulus of the produced structures and finite element analyses were performed, for comparison purposes. Linear correlations were found for the dimensions, porosity, and elastic modulus when comparing the CAD design with the SLM structures. The produced NiTi structures exhibit elastic moduli that match that of bone tissue, which is a good indication of the potential of these structures in orthopaedic implants.This work was supported by FCT (Fundação para a Ciência e Tecnologia) through the grant SFRH/BD/128657/2017 and the projects POCI-01-0145-FEDER-030353 (SMARTCUT), NORTE 01–0145_FEDER000018-HAMaBICo, UID/EEA/04436/2019 and UID/Multi/04044/2019

Climate adaptation, transitions, and socially innovative action-research approaches

Climate change may be a game-changer for scientific research by promoting a science that is grounded in linking the production of knowledge and societal action in a transition toward more sustainable development pathways. Here, we discuss participatory action-research (PAR) as a way of thinking and leading investigations that may promote incremental and transformative changes in the context of climate change adaptation research. Our exploration is addressed in the Portuguese context, where PAR and sustainable transition studies are still marginal, and adaptation processes are a recent topic on political agendas. We describe the characteristics of PAR and use two studies of adaptation to illustrate how research and practice co-evolve through interactive cycles. The two studies are works in progress, rather than completed PAR processes. Climate change adaptation is an ongoing and long-term process. Moreover, in Portugal, as in many regions of the world, climate change adaptation is a fairly new topic. Thus, both case studies are now initiating a long-term process of change and adaptation. The completion of one research cycle is a realistic expectation that we have achieved in the two case study experiences. In our discussion of the case studies, we consider how these experiences provide insights into the role of PAR for long-term regime changes. We conclude by pointing to the societal needs addressed by PAR, as a pragmatically oriented and context-specific research design. The approach can be complementary to other frameworks in sustainable transition studies such as transition management. Being more pragmatically oriented, PAR cycles may influence incrementally transformative changes that can be guided by transition management’s long-term design for governing sustainable transitions

An unusual cause of intra-abdominal calcification: A lithopedion

AbstractWe report a case of a 77-year-old female who was admitted to the emergency department complaining of diffuse abdominal pain for five days, associated with nausea, vomiting and constipation.Physical examination disclosed a large incarcerated umbilical hernia, which was readily apparent on supine abdominal plain films. These also showed a calcified heterogeneous mass in the mid-abdominal region, which was further characterized by CT as a lithopedion (calcified ectopic pregnancy). This is one of the few cases studied on a MDCT equipment, and it clearly enhances the post-processing abilities of this imaging method which allows diagnostic high-quality MIP images.Lithopedion is a rare entity, with less than 300 cases previously described in the medical literature. However, many reported cases corresponded to cases of skeletonization or collections of fetal bone fragments discovered encysted in the pelvic region at surgery or autopsy. It is thus estimated that true lithopedion is a much rarer entity.The diagnosis may be reached by a suggestive clinical history and a palpable mass on physical examination, while the value of modern cross-sectional techniques is still virtually unknown. Ultrasonography may depict an empty uterine cavity and a calcified abdominal mass of non-specific characteristics, and computed tomography or magnetic resonance imaging are able to reach a conclusive diagnosis and may additionally define the involvement of adjacent structures.The differential diagnosis includes other calcified pathologic situations, including ovarian tumors, uterine fibroids, urinary tract neoplasms, inflammatory masses or epiploic calcifications

Dry sliding wear behaviour of Ti-TiB-TiNx in-situ composite synthesised by reactive hot pressing

Ti and its alloys are attractive materials for a variety of fields; however, a major problem of Ti and its alloys is their poor wear resistance. It is known that reinforcing Ti with hard ceramic phases can substantially improve the wear resistance. Thus, Ti-TiB-TiNx in-situ metal matrix composites were synthesised by reactive hot pressing utilising Ti/BN powder blends with 23:1 Ti:BN weight ratio. Ball-on-plate reciprocating dry sliding wear tests were performed against a 10 mm of alumina ball under 10 N normal load, at a frequency of 1 Hz, and with the total stroke length of 3 mm during 1,800 s. Results showed that the total wear volume loss was significantly decreased on the composite (11.4 +/- 2.0 x 10(-3) mm(3)) as compared to the unreinforced Ti (40.9 +/- 4.2 x 10(-3) mm(3)) due to the strengthening effect of the in-situ reinforcing phases.This study was supported by The Calouste Gulbenkian Foundation through Programa de Mobilidade Academica para Professores and Portuguese Foundation for Science and Technology (FCT-Portugal), under the project EXCL/EMS-TEC/0460/2012. The authors also would like to thank Prof. Amilcar Ramalho (Universidade de Coimbra) for the provision of profilometry facilities.info:eu-repo/semantics/publishedVersio

Dynamic behaviour restructuring mediates dopamine-dependent credit assignment

Funding Information: We thank V. Athalye for feedback; A. Vaz and C. Carvalho for mouse colony management; the members of the Costa laboratory for comments; the members of the Scientific Hardware Platform, Histopathology Platform, Scientific Software Platform and Advanced Bioimaging & BioOptics Experimental Platform (member of the Portuguese Platform of Bioimaging (PPBI-POCI-01-0145-FEDER-022122) of the Champalimaud Institute for help; S. Mutlu, D. Bento, P. Carriço., P. Silva and J. Araujo for hardware/software assistance; I. Marcelo for assistance with multinomial logistic regression; N. Loureiro for assistance with inertial sensor calculations; M. Mendoça, C. Alcacer, H. Rodrigues and D. Peterka for help with experimental set-ups; the members of the M. Carey laboratory for sharing apparatus; S. Fusi for project feedback; and R. Junker for advice on dynamic range boxes. This work was supported by Life Sciences Research Fellowship and NINDS K99/R00 Award (1K99NS112575) granted to J.C.Y.T. and National Institute of Health funding (5U19NS104649) and the Aligning Science Across Parkinson’s (ASAP-020551) through the Michael J. Fox Foundation for Parkinson’s Research (MJFF) to R.M.C. The authors have applied a CC BY NC public copyright license for the manuscript. Publisher Copyright: © The Author(s) 2023.Initial dopamine self-stimulations reinforced not only the stimulation-producing target action, but also actions similar to the target action and actions that occurred a few seconds before stimulation, and repeated pairings led to a gradual refinement of the behavioural repertoire to home in on the target actions.publishersversionpublishe

International Standardization of Common Names for Iberian Endemic Freshwater Fishes

Las especies de peces dulceacuícolas endémicas de la península Ibérica carecen de nombres comunes en inglés, lo cual frecuentemente causa inconvenientes a los autores en el momento de publicar para una audiencia internacional. Con el objetivo de llenar este vacío, se presenta una lista actualizada de las especies de peces dulceacuícolas endémicas de la península Ibérica con una propuesta razonada de designación internacional estandarizada junto con los nombres comunes en español y/o portugués adoptados en los Libros Rojos NacionalesIberian endemic freshwater fishes do not have standardized common names in English, which is usually a cause of inconveniences for authors when publishing for an international audience. With the aim to tackle this problem, an updated list of Iberian endemic freshwater fish species is presented with a reasoned proposition of a standard international designation along with Spanish and/or Portuguese common names adopted in the National Red Data BooksOs peixes dulciaquícolas endémicos da Península Ibérica näo possuem um nome comum devidamente padronizado em Inglês, o que causa problemas aos investigadores quando publicam em revistas com uma audiência internacional. O presente trabalho procurou resolver esta questäo, incluindo uma lista actualizada das espécies piscícolas endémicas da Península Ibérica e uma proposta fundamentada de nomes comuns em Inglês, juntamente com as designaçöes comuns em Espanhol e/ou Português adoptadas nos respectivos Livros Vermelhos Nacionai