Redes de sensores de fibra ótica para monitorização in situ de baterias de ião de lítio

In this work, fiber optic sensor networks were developed to be integrated in commercially available lithium-ion batteries (cylindrical and prismatic) and pre-fabricated batteries in a laboratory environment (pouch cells), with the objective of monitoring in situ, operando and in real time, the internal and external variations of temperature and strain, under different environmental conditions and different charge and discharge rates. To this end, and in order to show the improved performance of fiber optic sensors in relation to the electronic ones, typically used in this type of application, their response time and resolution were compared. An improvement of 28% of the response time and a better resolution are attained with fiber optic sensors. Monitorization studies of the temperature and strain variations using fiber Bragg gratings (FBGs) in the cylindrical configuration have been made, as well as temperature and bi-directional strain variations in the prismatic configuration, under normal or abusive operating conditions, using the FBG method strain free. When the batteries were subjected to abusive operating conditions, it was evident that greater temperature and strain variations occur, being promoted by the rapid transport of lithium ions between the positive and negative electrodes. Due to the thermal expansion of the materials that compose the battery, its internal structure is an important parameter to consider and that can influence its behavior in terms of expansion and contraction. In order to monitor the thermal performance of lithium-ion prismatic batteries in different environmental conditions, studies were performed in which the battery operated at different discharge rates over different conditions of temperature and relative humidity, in order to simulate the performance of the battery in three distinct climates: cold, temperate, and dry. From these studies, the poor performance of this type of batteries in the cold climate, and consequent lower thermal performance was verified. A network of 37 FBG sensors has also been used to monitor the interfaces of a pack of 3 lithium polymer batteries connected in series. It was possible to perform a spatial and temporal thermal mapping under different discharge rates, and to identify areas that are more susceptible to the appearance of hot spots and that are capable of endanger its normal functioning. Hotter zones were detected near the current collectors, due to the higher density of lithium ions in this region. For the first time, the simultaneous discrimination of internal temperature and strain variations in lithium-ion batteries in the pouch cell configuration was carried out, through the incorporation of hybrid sensors, which combine the operational characteristics of the Fabry-Perot and FBG sensors. The evolution of the strain and temperature signals was followed by the proposed sensors and the largest strain variations were detected at the beginning of the discharge process, in the bottom position of the pouch cell. With the work developed in this Thesis, it is concluded that the integration of optical fiber sensors into lithium-ion batteries contributes to a better internal and external knowledge of the thermal performance and volume variations under different operating conditions. This might improve the safety conditions and optimize the design of the next generation of lithium-ion batteries.No presente trabalho, desenvolveram-se redes de sensores em fibra ótica para integrar em baterias comerciais de ião de lítio (cilíndricas e prismáticas) e em baterias pré-fabricadas em ambiente de laboratório (pouch cells), com o objetivo de monitorizar in situ, em funcionamento e em tempo real variações internas e externas de temperatura e deformação, sob diferentes condições ambientais e diferentes taxas de carga e descarga. Para tal, e de maneira a mostrar o melhor desempenho dos sensores de fibra ótica em relação aos eletrónicos tipicamente usados neste tipo de aplicação, os seus tempos de resposta e resolução foram comparados, obtendo-se uma melhoria de 28% do tempo de resposta e uma resolução superior com os sensores em fibra ótica. Foram feitos estudos da monitorização de variações de temperatura e deformação através de redes de Bragg em fibra (FBG) na configuração cilíndrica e variações de temperatura e deformação bidirecional na configuração prismática, aquando do seu funcionamento em condições normais e abusivas, através do método FBG strain-free. Quando as baterias foram submetidas a condições operacionais abusivas, ficou evidente que ocorrem maiores variações de temperatura e de deformação, sendo promovidas pelo rápido transporte dos iões de lítio entre os elétrodos positivo e negativo. Devido à expansão térmica dos materiais que compõem a bateria, a sua estrutura interna é um importante parâmetro a ter em consideração e que pode influenciar o seu comportamento em termos de expansão e contração. A fim de monitorizar o desempenho térmico de baterias prismáticas de ião de lítio em diferentes condições ambientais, realizaram-se estudos nos quais a bateria operou sob diferentes taxas de descarga em diferentes condições de temperatura e humidade relativa, por forma a simular o desempenho da bateria em três climas distintos: frio, temperado e seco. Destes estudos, constatou-se o fraco desempenho deste tipo de baterias no clima frio, e consequente inferior desempenho térmico. Uma rede de 37 sensores FBG foi ainda usada para monitorizar as interfaces de um pack de 3 baterias poliméricas de lítio, conectadas em série. Foi possível realizar um mapa térmico espacio-temporal para diferentes taxas de descarga, e identificar as zonas mais suscetíveis ao aparecimento de pontos quentes e capazes de colocar em risco o seu normal funcionamento. As zonas mais quentes foram detetadas próximas dos coletores de corrente, devido à superior densidade dos iões de lítio nesta região. Pela primeira vez, foi realizada a discriminação simultânea de variações internas de temperatura e deformação em baterias de ião lítio na configuração pouch cell, através da incorporação de sensores híbridos, que combinam as características operacionais dos sensores Fabry-Perot e FBG. A evolução da deformação e temperatura foi seguida pelos sensores propostos e as maiores variações de deformação foram detetadas no início do processo de descarga, na posição inferior da pouch cell. Com o trabalho desenvolvido nesta Tese, conclui-se que a integração de sensores em fibra ótica em baterias de ião de lítio contribui para um melhor conhecimento, interno e externo, do desempenho térmico e de variações de volume sob diferentes condições de funcionamento. Assim, poder-se-á melhorar as condições de segurança e otimizar o design da próxima geração de baterias de ião de lítio.Programa Doutoral em Engenharia Físic

Atividade eletromecânica da hidroxiapatite para a regeneração óssea

Mestrado em Materiais e Dispositivos BiomédicosO interesse pela aplicação de biomateriais para substituição e regeneração óssea aumentou significativamente na última década. A hidroxiapatite [HAp; Ca10(PO4)6(OH)2] é considerada um dos biomateriais mais promissores, devido à sua biocompatibilidade, bioatividade e osteocondutividade. O osso exibe um comportamento piezoelétrico e, como tal, desenvolve carga elétrica sob a aplicação de tensão mecânica e vice-versa, pensando-se que tal comportamento influencia a atividade de formação óssea. As propriedades elétricas da HAp preparada na forma de monolítico e na forma de filme fino têm sido estudadas nos últimos anos. Neste âmbito, foi referido que a HAp não apresenta resposta piezoelétrica. No entanto recentemente um coeficiente piezoelétrico foi reportado para filmes finos de HAp preparados pelo método sol gel. Perante esta aparente contradição pretende-se com este trabalho averiguar a existência de atividade piezoelétrica em monolíticos de HAp e comparar a sua resposta com a dos filmes finos, com o objetivo de contribuir para o esclarecimento destas diferenças de comportamento. Assim, prepararam-se monolíticos de HAp por prensagem uniaxial de pós através da mistura convencional de óxidos, seguido de uma caracterização morfológica por SEM, caracterização estrutural por DRX e caracterização dieléctrica através da medição de permitividade dielétrica, perdas dielétricas, resistividade elétrica e coeficiente piezoelétrico . Cerâmicos com densidade final de 96% apresentaram valores de permitividade dielétrica de 13, perdas dielétricas de 0,6 e uma resistividade elétrica na ordem dos Ωm para a frequência de 1MHz. Estes monolíticos apresentaram comportamento piezoeletrico nulo ( = 0 pC/N). Replicou-se a metodologia reportada na literatura relativa à preparação de filmes finos de HAp por sol gel, nos quais se mediu pela primeira vez um coeficiente piezoelétrico . A caraterização estrutural por DRX do filme fino obtido mostrou que o mesmo se apresentou sempre amorfo, não se conseguindo assim a sua caraterização dielétrica, contrariando o que é reportado na literatura relativamente à existência de um coeficiente piezoelétrico em filmes finos de HAp. Assim, concluiu-se que será necessário um estudo mais aprofundado e uma pesquisa mais criteriosa sobre a possibilidade de actividade piezoeléctrica da HAp. No estágio actual de conhecimento parece assim razoável continuar a admitir-se que o comportamento piezoelétrico exibido pelo osso deve ser fundamentalmente atribuído à presença das fibras de colagéneo e não da fase inorgânica de hidroxiapatite.The interest on biomaterials for bone replacement and regeneration has increased significantly in the last decade. Hydroxyapatite [HAp; Ca10(PO4)6(OH)2] is considered one of the most promising biomaterials due to its biocompatibility, bioactivity and osteoconductivity. The bone displays a piezoelectric behavior and therefore develops electric charges under the application of mechanical stress. This behavior influences the activity of bone formation. The electrical properties of HAp prepared as monolithic materials or as thin films have been studied in recent years. In this context, it has been referred that no piezoelectric response is exhibited by HAp. However a piezoeletric coefficient has recently been reported for HAp thin films prepared by the sol gel method. The purposes of the present work is to ascertain the existence of piezoelectric activity in bulk HAp and compare its response with the one exhibited by HAp thin films aiming to contribute for the understanding of those apparently contradictory behaviors. HAp as monolithic material was prepared by uniaxial pressing of powders produced by conventional mixing of oxides. Morphological characterization was assessed by SEM, crystalline phases were identified by XRD and for the dielectric characterization measuring of dielectric permittivity, dielectric losses, electrical resistivity and piezoelectric coefficient were performed. Ceramics with final density of 96% exhibited a dielectric permittivity of 13, dielectric losses of 0,6 and electrical resistivity around Ωm for 1MHz frequency. No piezoelectric behaviour ( = 0 pC/N) was found in these HAp monolithics. The next step in this work was to replicate the methodology reported in the literature on the preparation of HAp thin films by the sol gel technique aiming to measure a piezoelectric coefficient , as reported for the first time in the literature for HAp in film. Contrarily to what is claimed in the literature the obtained HAp thin films were essentially amorphous for all heat treatments performed and no reliable dielectrical characterization was achieved. Thus, it was concluded that a deeper study and a more thorough research on the possibility of piezoelectric activity of HAp should be carried out. At the present stage of knowledge it seems reasonable to assume that the piezoelectric behavior exhibited by the bone might be primarily attributed to the presence of collagen fibers rather than to its inorganic phase - HAp

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

Internal and External Temperature Monitoring of a Li-Ion Battery with Fiber Bragg Grating Sensors

The integration of fiber Bragg grating (FBG) sensors in lithium-ion cells for in-situ and in-operando temperature monitoring is presented herein. The measuring of internal and external temperature variations was performed through four FBG sensors during galvanostatic cycling at C-rates ranging from 1C to 8C. The FBG sensors were placed both outside and inside the cell, located in the center of the electrochemically active area and at the tab-electrode connection. The internal sensors recorded temperature variations of 4.0 ± 0.1°C at 5C and 4.7 ± 0.1° C at 8C at the center of the active area, and 3.9 ± 0.1° C at 5C and 4.0 ± 0.1° C at 8C at the tab-electrode connection, respectively. This study is intended to contribute to detection of a temperature gradient in real time inside a cell, which can determine possible damage in the battery performance when it operates under normal and abnormal operating conditions, as well as to demonstrate the technical feasibility of the integration of in-operando microsensors inside Li-ion cells

Resumo expandido, educação física escolar: atividades rítmicas e expressivas / Expanded abstract, school physical education: rhythmic and expressive activities

As atividades rítmicas e expressivas estão presentes nos PCNs, e com a elaboração da BNCC ela continua presente, mas de forma obrigatória. Este resumo expandido buscou visualizar como as atividades rítmicas e expressivas estão inseridas na Educação Física escolar. A revisão literária foi utilizada para fazer este resumo expandido

Pseudomonas aeruginosa Isolated from the Environment of a Veterinary Academic Hospital in Brazil - Resistance Profile

Background: The presence of resistant and potentially virulent bacterial strains in a veterinary hospital environment is a neglected problem.  Pseudomonas aeruginosa is an opportunistic microorganism present and circulating in the veterinary hospital environment, of clinical importance and zooanthroponotic transmission of P. aeruginosa has also been reported. The aim of this study was to characterize the population of P. aeruginosa present in a veterinary hospital environment by evaluating their resistance profile and biofilm production.Materials, Methods & Results: A total of 306 samples were collected from the veterinary hospital environment (swabs from consultation tables, surgical tables, door handles, hospitalization cages, stethoscopes, thermometers, and muzzles). The isolates were biochemically identified as belonging to the species Pseudomonas aeruginosa through nitrate to nitrite reduction, motility and oxidase test, growth at 42°C, pigment production, and alkalinization of acetamide. Antimicrobial resistance was tested using the minimum inhibitory concentration (MIC) test. Twenty seven isolates of P. aeruginosa were obtained, with a frequency of 8.8%. The detection of beta-lactamase production and biofilm formation genes by polymerase chain reaction (PCR). Two multidrug resistant (MDR) and 3 single-drug resistant (SDR) strains of P. aeruginosa were identified. Furthermore, it was observed that the strains carried genes related to beta-lactamase production (TEM and CTX-M group 25) and biofilm production (pelA, pslA, ppyR).Discussion: Pseudomonas aeruginosa is considered a major cause of opportunistic hospital infections, as it causes significant morbidity and mortality in immunosuppressed individuals, both in animals and in humans. Veterinary hospitals can harbor microorganisms that cause infections, as well as multiresistant agents. Normally, these environments have a large circulation of people and animals, which particularly enables a facilitated dissemination of these resistant microorganisms. Recently, the World Health Organization (WHO) listed carbapenem-resistant P. aeruginosa as one of 3 bacterial species in critical need for the development of new antibiotics to treat their infections. The data found in this work strengthen the knowledge on the antimicrobial resistance capacity that P. aeruginosa exhibits. The presence of 3 multiresistant strains further highlights the advanced stage of resistance of this bacterial species. The characterization of strains of this species in a veterinary hospital environment is crucial for the control of this population circulating in this environment, and the consequent adoption of more effective measures aimed at controlling its proliferation. The study of this bacterial species in a veterinary hospital environment has a direct impact on human health, due to the mechanisms of resistance and genetic variability that can occur between infections in different animal species and in humans. In view of that, professionals working in veterinary hospitals should be aware of the importance of controlling these microorganisms. Correct measures must be taken to sanitize the environment and utensils between animal care sessions, besides frequent hand washing by all employees and the use of protective equipment such as masks and gloves. The presence of potentially biofilm-producing MDR and SDR strains indicates the free circulation of these bacteria in the veterinary hospital environment. Thus, as a potentially pathogenic microorganism to humans and animals, containment measures must be taken to prevent this possible transmission.Keywords: bacteria, antimicrobial resistance, multidrug resistant, beta-lactamase, biofilm, veterinary care

TECNOLOGIAS DO CUIDADO UTILIZADAS PELO ENFERMEIRO NA ASSISTÊNCIA DE ENFERMAGEM EM SAÚDE MENTAL: Revisão Integrativa

Objetivo: identificar na literatura cientifica as tecnologias do cuidado utilizadas pelo enfermeiro na assistência de enfermagem em saúde mental. Método: trata-se de uma revisão integrativa da literatura com busca sistemática, realizada nas bases EMBASE, BVS e MEDLINE. Utilizou-se os descritores: Cuidados de Enfermagem, Tecnologia, Tecnologia Biomédica e Saúde Mental. Resultados: foram identificados 2024 artigos potencialmente elegíveis. Após seleção dos estudos, a amostra totalizou 12 artigos. Os estudos são dos últimos 5 anos (83,3%), foram publicados em revistas de enfermagem (83,3%), são primários qualitativos (58,3%), possuem nível de evidência VI (67,7%) e utilizam predominantemente tecnologias leves (100%). Dentre as tecnologias utilizadas, as mais citadas foram acolhimento e musicoterapia. Reflete-se sobre as tecnologias disponíveis e que são utilizadas, bem como a criação de novas em concordância com as novas demandas e necessidades da área estudada.  Considerações finais: Os enfermeiros devem atuar pautando-se em um conhecimento técnico, cientifico e humanístico, na qual os usos das tecnologias do cuidado podem ofertar uma maior qualidade na assistência quando utilizadas de forma adequada

Acute effects of transcranial direct current stimulation (tDCS) on peak torque and 5000 m running performance: a randomized controlled trial

The benefits of transcranial direct current stimulation (tDCS) on brain function, cognitive response, and motor ability are well described in scientific literature. Nevertheless, the effects of tDCS on athletes’ performance remain unclear. To compare the acute effects of tDCS on the running performance of 5000 m (m) runners. Eighteen athletes were randomized into Anodal (n = 9) groups that received tDCS for 20 min and 2 mA, and Sham (n = 9), in the motor cortex region (M1). Running time in 5000 m, speed, perceived exertion (RPE), internal load and peak torque (Pt) were evaluated. The Shapiro–Wilk test followed by a paired Student’s t-test was used to compare Pt and total time to complete the run between the groups. The running time and speed of the Anodal group (p = 0.02; 95% CI 0.11–2.32; d = 1.24) was lower than the Sham group (p = 0.02, 95% CI 0.05–2.20; d = 1.15). However, no difference was found in Pt (p = 0.70; 95% CI − 0.75 to 1.11; d = 0.18), RPE (p = 0.23; 95% CI − 1.55 to 0.39; d = 0.60) and internal charge (p = 0.73; 95% CI − 0.77 to 1.09; d = 0.17). Our data indicate that tDCS can acutely optimize the time and speed of 5000 m runners. However, no alterations were found for Pt and RPE

Aspectos sociais e culturais envolvidos no processo de transição identitária da população trans

The separation between sex and gender, materialized by the notion of gender identity, was crucial to establish the needs of trans people. However, the influence of the cisnormative matrix can still be seen. Based on this premise, this study, as a qualitative research, aimed to deepen the knowledge and understanding of individual and, above all, social aspects, linked to the process of identity transition of this public, for this, an exploratory and descriptive research was carried out. Fourteen transgender people living in the city of Mossoró/RN were interviewed. Four categories of analysis were found: The fortifications of history and support, and lost basic rights, religion and affective relationships. Thus, the consequences of the imposition of heteronormativity and gender binarism in the lives of transgender people were discussed.A separação entre sexo e gênero, materializada pela noção de identidade de gênero, foi crucial para estabelecer as necessidades das pessoas trans. No entanto, vê-se ainda a influência da matriz cisnormativa. Partindo dessa premissa, esse estudo, enquanto pesquisa qualitativa, teve por objetivo aprofundar o conhecimento e o entendimento dos aspectos individuais, sobretudo, sociais, ligados ao processo de transição identitária deste público, para isso, realizou-se uma pesquisa exploratória e descritiva. Foram entrevistadas 14 pessoas transgêneros residentes no município de Mossoró/RN Encontrou-se 4 categorias de análise: As fortificações da história e do apoio e, direitos básicos perdidos, religião e relacionamentos afetivos. Assim, discutiu-se as consequências da imposição da heteronormatividade e do binarismo de gênero na vida das pessoas transgênero