Using biotechnology to solve engineering problems Non-destructive testing of microfabrication components

Fundacao para a Ciencia e a Tecnologia, I.P. (FCT), Portugal, for financial support under program "Investigador FCT 2013" (IF/01203/2013/CP1163/CT0002) and UID/BIO/04565/2013. TS and RM acknowledge FCT for PEst-OE/EME/UI0667/2014 and UID/EMS/00667/2013. The study was also partially supported by project PTDC/EME-TME/118678/2010.In an increasingly miniaturised technological world, non-destructive testing (NDT) methodologies able to detect defects at the micro scale are necessary to prevent failures. Although several existing methods allow the detection of defects at that scale, their application may be hindered by the small size of the samples to examine. In this study, the application of bacterial cells to help the detection of fissures, cracks, and voids on the surface of metals is proposed. The application of magnetic and electric fields after deposition of the cells ensured the distribution of the cells over the entire surfaces and helped the penetration of the cells inside the defects. The use of fluorophores to stain the cells allowed their visualisation and the identification of the defects. Furthermore, the size and zeta potential of the cells and their production of siderophores and biosurfactants could be influenced to detect smaller defects. Micro and nano surface defects made in aluminium, steel, and copper alloys could be readily identified by two Staphylococcus strains and Rhodococcus erythropolis cells.publishersversionpublishe

Embedded fiber sensors to monitor temperature and strain of polymeric parts fabricated by additive manufacturing and reinforced with NiTi wires

POCI-01-0145-FEDER-016414 (FIBR3D) BI/UI96/6642/2018 BI/UI96/6643/2018 PD/BD/128265/2016 UID/CTM/50025/2019 UIDB/00667/2020 FCT-SFRH/BD/146885/2019 UIDB/50025/2020 UIDP/50025/2020This paper focuses on three main issues regarding Material Extrusion (MEX) Additive Manufacturing (AM) of thermoplastic composites reinforced by pre-functionalized continuous Nickel–Titanium (NiTi) wires: (i) Evaluation of the effect of the MEX process on the properties of the pre-functionalized NiTi, (ii) evaluation of the mechanical and thermal behavior of the composite material during usage, (iii) the inspection of the parts by Non-Destructive Testing (NDT). For this purpose, an optical fiber sensing network, based on fiber Bragg grating and a cascaded optical fiber sensor, was successfully embedded during the 3D printing of a polylactic acid (PLA) matrix reinforced by NiTi wires. Thermal and mechanical perturbations were successfully registered as a consequence of thermal and mechanical stimuli. During a heating/cooling cycle, a maximum contraction of ≈100 µm was detected by the cascaded sensor in the PLA material at the end of the heating step (induced by Joule effect) of NiTi wires and a thermal perturbation associated with the structural transformation of austenite to R-phase was observed during the natural cooling step, near 33.0◦ C. Regarding tensile cycling tests, higher increases in temperature arose when the applied force ranged between 0.7 and 1.1 kN, reaching a maximum temperature variation of 9.5 ± 0.1◦ C. During the unload step, a slope change in the temperature behavior was detected, which is associated with the material transformation of the NiTi wire (martensite to austenite). The embedded optical sensing methodology presented here proved to be an effective and precise tool to identify structural transformations regarding the specific application as a Non-Destructive Testing for AM.publishersversionpublishe

Particles’ distribution enhancing in aluminum-based composites produced by upward friction stir processing

Funding Information: Open access funding provided by FCT|FCCN (b-on). CV and TGS acknowledge Fundação para a Ciência e a Tecnologia (FCT-MCTES) for its financial support via projects UIDB/00667/2020 and UIDP/00667/2020 (UNIDEMI). PMF also acknowledges FCT-MCTES for its financial support via the PhD scholarship UI/BD/151055/2021. PLI would like to acknowledge FCT-MCTES for its financial support via the PhD scholarship FCT-SFRH /BD/146885/2019. RJCS acknowledges national funds from FCT-MCTES, in the scope of the project UIDB/50025/2020–2023 of the CENIMAT/i3N. Publisher Copyright: © 2023, The Author(s).A new variant of friction stir processing named upward friction stir processing (UFSP) is a promising approach to control particles’ distribution and promote a more uniform distribution over a larger processed area. This variant involves using two sheets with functional particles between them to produce metallic composites. A spacer is used to ensure the desired quantity and uniform distribution of the particles and prevent sputtering. This technique promotes an upward flow to introduce more particles with a uniform distribution in the processed volume, avoiding discrete holes or grooves. This study involved enhancing the particles’ distribution by varying process parameters. The resulting trial with the best particles’ distribution was characterized by means of light microscopy, eddy current testing, microhardness mapping, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The study revealed that UFSP can improve the particles’ distribution in the stir zone of metallic composites, especially when multi-passes are performed towards the retreating side of the plates. The process parameters that produced an improvement in particles’ distribution were six passes with an offset of 1 mm towards the retreating side, the tool rotation and processing speed of 900 rev/min, and 180 mm/min, respectively, and a spacer’s thickness of 0.5 mm. The resulting hardness and electrical conductivity profiles show that the UFSP technique can significantly affect material’s properties, including mechanical strength, particularly when processing with tool offset towards the retreating side. Furthermore, the hardness increased by about 22% in composites produced with the addition of reinforcement particles. However, for some aluminum alloys, the properties decreased under such conditions. These findings highlight the potential of UFSP for producing functionalized materials with tailored properties, while also underscoring the importance of careful parameters selection to optimize the material´s performance. Graphical Abstract: [Figure not available: see fulltext.].publishersversioninpres

Overview and Development of the Child Health and Mortality Prevention Surveillance Determination of Cause of Death (DeCoDe) Process and DeCoDe Diagnosis Standards

Mortality surveillance and cause of death data are instrumental in improving health, identifying diseases and conditions that cause a high burden of preventable deaths, and allocating resources to prevent these deaths. The Child Health and Mortality Prevention Surveillance (CHAMPS) network uses a standardized process to define, assign, and code causes of stillbirth and child death (<5 years of age) across the CHAMPS network. A Determination of Cause of Death (DeCoDe) panel composed of experts from a local CHAMPS site analyzes all available individual information, including laboratory, histopathology, abstracted clinical records, and verbal autopsy findings for each case and, if applicable, also for the mother. Using this information, the site panel ascertains the underlying cause (event that precipitated the fatal sequence of events) and other antecedent, immediate, and maternal causes of death in accordance with the International Classification of Diseases, Tenth Revision and the World Health Organization death certificate. Development and use of the CHAMPS diagnosis standards—a framework of required evidence to support cause of death determination—assures a homogenized procedure leading to a more consistent interpretation of complex data across the CHAMPS network. This and other standardizations ensures future comparability with other sources of mortality data produced externally to this project. Early lessons learned from implementation of DeCoDe in 5 CHAMPS sites in sub-Saharan Africa and Bangladesh have been incorporated into the DeCoDe process, and the implementation of DeCoDe has the potential to spur health systems improvements and local public health action

Mortality Surveillance Methods to Identify and Characterize Deaths in Child Health and Mortality Prevention Surveillance Network Sites

Despite reductions over the past 2 decades, childhood mortality remains high in low- and middle-income countries in sub-Saharan Africa and South Asia. In these settings, children often die at home, without contact with the health system, and are neither accounted for, nor attributed with a cause of death. In addition, when cause of death determinations occur, they often use nonspecific methods. Consequently, findings from models currently utilized to build national and global estimates of causes of death are associated with substantial uncertainty. Higher-quality data would enable stakeholders to effectively target interventions for the leading causes of childhood mortality, a critical component to achieving the Sustainable Development Goals by eliminating preventable perinatal and childhood deaths. The Child Health and Mortality Prevention Surveillance (CHAMPS) Network tracks the causes of under-5 mortality and stillbirths at sites in sub-Saharan Africa and South Asia through comprehensive mortality surveillance, utilizing minimally invasive tissue sampling (MITS), postmortem laboratory and pathology testing, verbal autopsy, and clinical and demographic data. CHAMPS sites have established facility- and community-based mortality notification systems, which aim to report potentially eligible deaths, defined as under-5 deaths and stillbirths within a defined catchment area, within 24-36 hours so that MITS can be conducted quickly after death. Where MITS has been conducted, a final cause of death is determined by an expert review panel. Data on cause of death will be provided to local, national, and global stakeholders to inform strategies to reduce perinatal and childhood mortality in sub-Saharan Africa and South Asia

Assessment of the energetic efficiency of friction stir welding/processing

Funding Information: PLI would like to acknowledge Fundação para a Ciência e a Tecnologia (FCT-MCTES) for its financial support via the PhD scholarship FCT-SFRH/BD/146885/2019 . TGS, JPO and FF acknowledge Project 24534 - “INFANTE - Microssatélite para Vigilância Marítima, Observação da Terra e IoT no contexto de constelações”, supported by Operational Program for Competitiveness and Internationalization (COMPETE 2020) and Lisbon Regional Operational Programme (Lisboa 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). PLI, JPO and TGS acknowledge Fundação para a Ciência e a Tecnologia (FCT - MCTES) for its financial support via the project UIDB/00667/2020 and UIDP/00667/2020 (UNIDEMI). JPO acknowledges the funding of CENIMAT/i3N by national funds through the FCT -Fundação para a Ciência e a Tecnologia, I.P., within the scope of Multiannual Financing of R&D Units, reference UIDB/50025/2020-2023 . Publisher Copyright: © 2023 The AuthorsThis paper scrutinizes and goes beyond previously published results on the analysis of the energy flow during friction stir welding/processing (FSW/P). An in-depth scientific method was used to assess the individual energetic contribution arising from the main components within the FSW/P system. This investigation was performed during FSW/P of AA7075 with different tool rotations and travel speeds. The main contributors to energy losses during the FSW/P process include the FSW/P tool, anvil, unprocessed base material, and the surrounding environment. It was found that only about 25 % of the total energy is effectively used to perform the welding/processing, while the remaining energy dissipates through heat into the tooling and clamping system. Additionally, around 6 % of the energy is lost towards the base material, forming the heat-affected zone (HAZ). These results suggest that proper selection of the anvil material offers a promising opportunity to enhance effective energy efficiency, considering that approximately 60 % of the total energy input is lost through this component. Addressing this substantial energy loss becomes essential for achieving a more energetically sustainable industrial application of the FSW/P process.Peer reviewe

Non-destructive microstructural analysis by electrical conductivity: Comparison with hardness measurements in different materials

J.P. Oliveira, R.M. Miranda and Telmo G. Santos acknowledgethe Portuguese Fundacao para a Ciencia e a Tecnologia (FCT, I.P.) for its financial support via the project PEst-OE/EME/UI0667/2014. Telmo G. Santos and R.M. Miranda also acknowledge Project Hi2TRUST, (Refa-3335), supported by Fundo Europeu de Desenvolvimento Regional (FEDER), Programa Operacional Regional de Lisboa (Lisb@2020 and Portugal2020).The use of non-destructive evaluation (NDE) techniques for assessing microstructural changes in processed materials is of particular importance as it can be used to assess, qualitatively, the integrity of any material/structure. Among the several NDE techniques available, electrical conductivity measurements using eddy currents attract great attention owing to its simplicity and reliability. In this work, the electrical conductivity profiles of friction stir processed Ti6Al4V, Cu, Pb, S355 steel and gas tungsten arc welded AISI 304 stainless steel were determined through eddy currents and four-point probe. In parallel, hardness measurements were also performed. The profiles matched well with the optical macrographs of the materials: while entering in the processed region a variation in both profiles was always observed. One particular advantage of electrical conductivity profiles over hardness was evident: it provides a better resolution of the microstructural alterations in the processed materials. Moreover, when thermomechanical processing induces microstructural changes that modify the magnetic properties of a material, eddy currents testing can be used to qualitatively determine the phase fraction in a given region of the material. A qualitative relation between electrical conductivity measurements and hardness is observed.authorsversionpublishe

Nova Técnica de END Baseada em Células Bacterianas para Detecção de Micro e Nano Defeitos Superficiais

ResumoTrabalhos recentes têm demostrado que filmes com células bacterianas (CB) podem ser usados como uma nova técnica de Ensaios Não Destrutivos (END) fiável para a deteção e caracterização de micro e nano defeitos superficiais. As CB podem ser usadas também numa perspetiva de caracterização da textura e topografia de superfícies. Esta nova técnica de END pretende explorar a intencionalidade e os atributos de vida das CB, nomeadamente: a sua reduzida dimensão, elevada capacidade de penetração, mobilidade, aderência, fluorescência, sensibilidade a campos elétricos e magnéticos, morte e reprodutibilidade. Neste trabalho descreve-se a metodologia usada para aplicação desta nova técnica de END, e é realizada a sua validação experimental em diferentes materiais com distintas morfologias de defeitos. Os resultados mostram que as CB permitem detetar eficazmente os defeitos presentes no bloco padrão Tipo1 ISO 3452-3 com 0,5 µm de espessura, defeitos do tipo fissura em soldadura laser de titânio, micro indentações em INCONEL, e nano indentações em ouro. Demonstrou-se assim a viabilidade desta técnica e o seu grande potencial para revelar defeitos em peças para diferentes aplicações industriais

Production and characterization of functionally graded NiTi shape memory alloys by Joule effect

Localized heat treatments via Joule effect were performed on cold-drawn NiTi strips to produce a functionallygraded material (FGM). Three zones where locally heat treated at 300, 350, and 400 °C for 10 min followed byair cooling. Multiscale and multiphenomena characterization of the obtained FGM was performed through infraredtemperature testing, four-point probe and eddy current testing, mechanical testing and synchrotron X-raydiffraction. The effect of these localized heat treatments is clearly observed by different techniques. The use ofthese short and localized heat treatments avoids the need of highly expensive manufacturing routes typicallyused to obtain the same effect on NiTi shape memory alloys, thus opening new possibilities for processing theseadvanced engineering alloys

Functionalized material production via multi-stack Upward Friction Stir Processing (UFSP)

| openaire: EC/H2020/730872/EU//CALIPSOplusAn innovative friction stir processing variant, named Upward Friction Stir Processing (UFSP), for producing customized materials with multifunctional particles is presented. In the UFSP, an upward flow is used to disperse these functional particles in a metallic matrix, in opposition to the widely used downward flow. As a proof of concept, SiC particles were introduced and dispersed into an aluminum alloy AA7075-T651 matrix to study different process parameters and to validate this novel material processing technology. Six different small-sized ingots were produced and compared to the conventional FSP technology. The microstructural evolution is studied by means of light microscopy, eddy current testing, microhardness mapping and advanced characterization techniques, such as high-energy synchrotron X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy and electron backscatter diffraction. The number of passes was seen to greatly impact the particle distribution. Additionally, UFSP promotes a more uniform particle distribution over a larger processed area, when the lateral tool offset progress along the retreating side.Peer reviewe