Influence of the chloride attack on the post-cracking behavior of Recycled Steel Fiber Reinforced Concrete

The main purpose of the present work is to study the mechanical behavior and durability performance of recycled steel fiber reinforced concrete (RSFRC) under a chloride environment. To this end, the effect of chloride attack on the load-carrying capacity of pre-cracked RSFRC round panels is investigated by performing round panel tests supported on three points (RPT-3ps), considering the influence of the crack width and the fiber distribution/orientation profile. In addition, the influence of the adopted chloride exposure conditions on the post-cracking constitutive laws of the developed RSFRC is also assessed by performing numerical simulations for the prediction of the long-term performance of RSFRC under these aggressive conditions. The tensile stress–crack width relationship of RSFRC is derived by performing an inverse analysis with the RPT-3ps results. The obtained experimental and numerical results show a negligible effect of the chloride attack on the post-cracking behavior of RSFRC for the chloride exposure conditions and pre-crack width levels adopted in this study.This research was funded by C.F. research grant PD/BD/113638/2015 provided by Fundação para a Ciência e a Tecnologia (FCT) through the Doctoral Program in Eco Construction and Rehabilitation–EcoCoRe, and J.B. through the project ICoSyTec (POCI-01-0145-FEDER-027990) financed by FCT and co-funded by FEDER through Operational Competitiveness and Internationalization Programme (POCI)

An experimental investigation on the post-cracking behaviour of Recycled Steel Fibre Reinforced Concrete

Steel fibres resulting from the industry of tyre recycling can be efficiently employed for the reinforcement of concrete structures. Recycled Steel Fibre Reinforced Concrete (RSFRC) is a promising candidate with technical, environmental and economic benefits for the development of ductile, high strength and durable constructive systems, as it is required for breakwater elements used on the protection of coastal zones. For assessing the potentialities of recycled steel fibres (RSF) as concrete reinforcement, an experimental program was performed in the present work by comparing the following properties of concrete reinforced with industrial steel fibres (ISF) and with RSF: compressive strength, modulus of elasticity, flexural strength, flexural toughness and indirect tensile strength. Under chloride attack, the durability performance of RSFRC requires the assessment of its corrosion resistance. To evaluate the corrosion effects on the post-cracking response of RSFRC, double edge wedge splitting tensile tests were conducted in RSFRC specimens previously exposed to aggressive chloride environment. The obtained results demonstrate that, for the adopted industrial and recycled fibres, the last ones had not inferior post-cracking strengthening performance than the first ones. The corrosion action caused a slight decrease of the average post-cracking tensile strength of the RSFRC. The small percentage of rubber attached to RSF surface had a negligible effect in the corrosion resistance of RSFRC.FCT through PTDC/ECMEST/2635/2014 project, as well as the collaboration of CiviTest Company in the production of concretes. The first author would like to thank the FCT for the financial support through the Research Grant PD/BD/113638/2015. The supplying of RSF and ISF from Twincon and Maccaferri Companie

Multinomial logistic regression in worker’s health

In European countries, namely in Portugal, it is common to hear some people mentioning that they are exposed to excessive and continuous psychosocial stressors at work. This is increasing in diverse activity sectors, such as, the Services sector. A representative sample was collected from a Portuguese Services’ organization, by applying a survey (internationally validated), which variables were measured in five ordered categories in Likert-type scale. A multinomial logistic regression model is used to estimate the probability of each category of the dependent variable general health perception where, among other independent variables, burnout appear as statistically significant

An experimental study on the corrosion susceptibility of Recycled Steel Fiber Reinforced Concrete

Steel fibers resulting from the industry of tire recycling can be efficiently employed in concrete to improve its mechanical performance, such as post-cracking load bearing and energy absorption capacity. Under chloride attack, an important aspect of Recycled Steel Fiber Reinforced Concrete (RSFRC) durability is its corrosion resistance. However, the insufficient knowledge on this domain contributes for a conservative design philosophy, which can compromise the cost competitiveness of RSFRC and prevent its application in elements where this occurrence, even eventual, is not acceptable. In the present work, an experimental program was performed with the aim of assessing the corrosion susceptibility of RSFRC including the characterization of the micro-mechanical properties and the corrosion resistance of recycled steel fiber (RSF) by means of nano-indentation testing, electrochemical monitoring techniques and scanning electron microscopy (SEM) analysis. The influence of the small rubber debris attached to the RSF surface was also analyzed by using two distinct pre-treatment methods. The adhesive bond behavior between the RSF and the surrounding self-compacting concrete (SCC) matrix was analyzed by performing monotonic RSF pullout tests. Double edge wedge splitting (DEWS) tests were conducted for evaluating the corrosion effects on the post-cracking response of RSFRC.CiviTest Company and the Scientific and Technological Research Assistance Centre (CACTI) of the University of Vigo. The first author would like to thank the FCT for the financial support through the Research Grant PD/BD/113638/2015. The third author acknowledges the grant SFRH/BSAB/114302/2016 provided by FCT. Part of this work is supported by FCT with the reference project UID/EEA/04436/2013, COMPETE 2020 with the code POCI-01- 0145-FEDER-006941. Finally the support of the FCT through the project PTDC/ECM-EST/2635/201

High-yield production of nano-lateral size graphene oxide by high-power ultrasonication

Nanographene oxide (GOn) constitutes a nanomaterial of high value in the biomedical field. However, large scale production of highly stable aqueous dispersions of GOn is yet to be achieved. In this work, we explored high-power ultrasonication as a method to reduce particle size of GO and characterized the impact of the process on the physicochemical properties of the material. GOn was obtained with lateral dimensions of 99 ± 43 nm and surface charge of -39.9 ± 2.2 mV. High-power ultrasonication enabled an improvement of stability features, particularly by resulting in a decrease of the average particle size, as well as zeta potential, in comparison to GO obtained by low-power exfoliation and centrifugation (287 ± 139 nm; -29.7 ± 1.2 mV). Remarkably, GOn aqueous dispersions were stable for up to 6 months of shelf-time, with a global process yield of 74%. This novel method enabled the production of large volumes of highly concentrated (7.5 mg mL-1) GOn aqueous dispersions. Chemical characterization of GOn allowed the identification of characteristic oxygen functional groups, supporting high-power ultrasonication as a fast, efficient, and productive process for reducing GO lateral size, while maintaining the material’s chemical features.This work was financed by FEDER funds through the COMPETE 2020—Operacional Programme for Competitiveness and Internationalisation (POCI), Portugal 2020, and by national funds (PIDDAC) through FCT/MCTES in the framework of the project POCI-01-0145-FEDER-031143, and Base Funding—UIDB/00511/2020 of the Laboratory for Process Engineering, Environment, Biotechnology and Energy—LEPABE. Authors would also like to thank the support of i3S Scientific Platforms and respective funding: HEMS, member of the national infrastructure PPBI—Portuguese Platform of Bioimaging: POCI-01-0145-FEDER-022122; and Biointerfaces and Nanotechnology (BN) Laboratory, Portuguese Funds through FCT, UID/BIM/04293/2019. Artur Pinto thanks the Portuguese Foundation for Science and Technology (FCT) for the financial support of his work contract through the Scientific Employment Stimulus—Individual Call—[CEECIND/03908/2017]

Estudo experimental da suscetibilidade à corrosão do betão reforçado com fibras de aço recicladas

As fibras de aço provenientes da indústria da reciclagem de pneus possuem elevada potencialidade no reforço efetivo do betão, especialmente ao nível do seu comportamento à tração e resistência ao impacto. Neste sentido, o betão reforçado com fibras de aço recicladas (BRFAR) constitui uma solução ambientalmente mais sustentável na produção de blocos de elevada eficiência e durabilidade para a construção de quebra-mares para proteção costeira. Em ambiente marítimo, a possibilidade de corrosão induzida por cloretos das fibras de aço recicladas é um dos principais mecanismos de deterioração do BRFAR que requer especial atenção. No entanto, a investigação neste domínio ainda é escassa contribuindo para uma filosofia conservadora de utilização do BRFAR que compromete a sua competitividade económica. Com o intuito de avaliar a suscetibilidade à corrosão do BRFAR, no presente trabalho desenvolveuse um programa experimental de caracterização da resistência à corrosão das fibras de aço recicladas por intermédio de técnicas eletroquímicas. A influência da corrosão no comportamento pós-fendilhação do BRFAR foi avaliada através de ensaios de tração por compressão diametral realizados em provetes previamente sujeitos a corrosão, por exposição a um ambiente agressivo de cloretos. As fibras recicladas utilizadas neste trabalho possuem pequenos detritos de borracha aderidos à sua superfície. Utilizando dois métodos distintos de remoção destes detritos foi avaliada a influência quer dos métodos aplicados, como da presença dos detritos na resistência das fibras à corrosão. Os resultados revelaram uma ligeira diminuição da resistência pós-fendilhação nos provetes de BRFAR submetidos a imersão de cloretos. Verificou-se ainda que os detritos de borracha aderidos à superfície das fibras recicladas tiveram um efeito desprezável na resistência à corrosão do BRFAR.Este trabalho foi desenvolvido no âmbito do projeto InOlicTower, PTDC/ECM-EST/2635/2014. Um especial agradecimento à empresa Twincon pelo fornecimento das fibras de aço recicladas e à empresa CiviTest pelo apoio na produção do BRFAR. O primeiro autor agradece a bolsa de doutoramento PD/BD/113638/2015 concedida pela FCT

Relação entre bem-estar social, gênero e outros fatores sociodemográficos

Resumen: Introducción: En la actualidad se ha demostrado que el bienestar social representa un factor psicosocial de gran relevancia para el contexto académico en diversidad de niveles educativos. El objetivo de este estudio fue analizar el bienestar social percibido de adolescentes y otros factores sociodemográficos, como el género o el nivel académico de los padres y madres. Se realizó un estudio no experimental de carácter descriptivo y corte transversal mediante una única medición en un único grupo. La muestra estuvo representada por 128 estudiantes adolescentes (de 12 a 18 años de edad) de un centro público de Córdoba. Como instrumento se aplicó la escala de bienestar social desarrollada por Blanco y Díaz (2005) obteniéndose una fiabilidad aceptable de α = 0,822, empleándose para el análisis de los datos el software IBM SPSS. Los resultados indicaron niveles adecuados de bienestar social de forma global, siendo el género algo masculino algo superior al femenino. Asimismo, el género masculino estaba asociado a unos mayores niveles de actualización social, al igual que unos mayores niveles de contribución y coherencia social en función de los estudios de los padres y las madres respectivamente. Todo ello, revela la consideración de dichos factores sociodemográficos a la hora de intervenir y trabajar el bienestar social en jóvenes adolescentes.Abstract: Introduction: Nowadays, it has been shown that social well-being represents a psychosocial factor of great relevance for the academic context in several educational levels. The objective of this study was to analyze the perceived social well-being of adolescents and other sociodemographic factors, such as gender or the academic level of fathers and mothers. A non-experimental descriptive and cross-sectional study was carried out by means of a single measurement in a single group. The sample was represented by 128 adolescent students (12 to 18 years old) from a public high school from Córdoba. As main instrument, the social well-being scale developed by Blanco y Díaz (2005) was applied, obtaining an acceptable reliability of α = 0.822, and using the IBM SPSS software for data analysis. The results indicated adequate levels of social well-being in a global way, with gender being somewhat masculine rather than feminine. Likewise, the masculine gender was associated with higher levels of social updating, as well as higher levels of contribution and social coherence according to the studies of the fathers and mothers respectively. All this reveals the consideration of these sociodemographic factors when intervening and working on social well-being in young adolescents.Resumo: Introdução: Atualmente, tem sido demonstrado que o bem-estar social representa um fator psicossocial de grande relevância para o contexto acadêmico em uma diversidade de níveis educacionais. O objetivo deste estudo foi analisar o bem-estar social percebido de adolescentes e outros fatores sociodemográficos, como gênero ou nível acadêmico de pais e mães. Um estudo descritivo e transversal não experimental foi realizado por meio de uma única medida em um único grupo. A amostra foi representada por 128 estudantes adolescentes (12 a 18 anos) de um centro público em Córdoba. Como instrumento, foi aplicada a escala de bem-estar social desenvolvida por Blanco y Díaz (2005), obtendo-se uma confiabilidade aceitável de α = 0,822, utilizando o software IBM SPSS para análise de dados. Os resultados indicaram níveis adequados de bem-estar social de maneira global, com gênero sendo um tanto masculino e não feminino. Da mesma forma, o gênero masculino esteve associado a maiores níveis de atualização social, assim como maiores níveis de contribuição e coerência social, de acordo com os estudos dos pais e mães, respectivamente. Tudo isso revela a consideração desses fatores sociodemográficos ao intervir e trabalhar no bem-estar social em adolescentes jovens

Análise e relação entre o uso problemático de videogames e o nível de atividade física em adolescentes de Huelva

Resumen: Introducción: En el actual estudio se trata de conocer si existe una relación significativa entre el uso de videojuegos y el nivel de actividad física en una muestra de 636 adolescentes pertenecientes a tres centros educativos de la provincia de Huelva, ya que se cree en el presente estudio que son aquellos que pueden beneficiarse mejor de las ventajas de coordinar actividad física y videojuegos, así como prevenir conductas problemáticas tanto de videojuegos como de inactividad física y la prevención de enfermedades que puedan surgir a raíz de esto. Objetivos: Definir niveles de uso problemático de videojuegos y actividad física, en una muestra de adolescentes. Analizar y relacionar la información obtenida sobre el uso de videojuegos y el nivel de actividad física. Métodos: Se realizó un estudio descriptivo de corte transversal en el que se aplicaron los instrumentos CERV, PAQ-A entre marzo y abril de 2018. Resultados y discusión: Como principales resultados se pudo observar que tanto en el uso problemático de videojuegos como en el nivel de actividad física, los chicos adolescentes tenían puntuaciones más altas que las chicas adolescentes aunque por lo general el nivel de actividad física tiene un nivel medio-bajo en ambos sexos. Otra conclusión a destacar es que tanto chicos como chicas adolescentes apenas tienen problemas relacionados con los videojuegos y que la mayor parte de ellos no cumplen las recomendaciones de actividad física mínima de forma semanal, lo cual puede llegar a incidir negativamente en su salud física y psicológica.Abstract: Introduction: The current study seeks to know if there is a significant relationship between the use of video games and the level of physical activity in a sample of 636 adolescents belonging to three educational centers in the province of Huelva, since it is believed in the present study that are those that can benefit better from the advantages of coordinating physical activity and video games, as well as preventing problematic behaviors of both video games and physical inactivity and the prevention of diseases that may arise as a result of this. Aim: Define levels of problematic use of video games and physical activity in a sample of adolescents. Analyze and relate the information obtained about the use of video games and the level of physical activity. Results & discussion: As main results it was observed that both in the problematic use of video games and in the level of physical activity, the adolescent boys had higher scores than the adolescent women although in general the level of physical activity has a medium-low level in both sexes. Another conclusion to emphasize is that both sexes boys and girls, hardly have problems related to video games and that most of them do not meet the minimum physical activity recommendations on a weekly basis, which can have a negative impact on their physical and psychological health.Resumo: Introdução: O presente estudo busca saber se existe uma relação significativa entre o uso de videogames e o nível de atividade física em uma amostra de 636 adolescentes pertencentes a três centros educacionais da província de Huelva, pois acredita-se no presente estudo que são aqueles que podem se beneficiar melhor das vantagens de coordenar a atividade física e os videogames, bem como evitar comportamentos problemáticos dos videogames e da inatividade física e a prevenção de doenças que possam surgir como resultado disso. Objectivos: Definir níveis de uso problemático de videogames e atividade física em uma amostra de adolescentes. Analisar e relacionar as informações obtidas sobre o uso de videogames e o nível de atividade física. Métodos: Foi realizado um estudo descritivo transversal, no qual foram aplicados os instrumentos CERV, PAQ-A.Texto. Resultados e Discussão: Como principais resultados observou-se que tanto no uso problemático de videogames quanto no nível de atividade física, os adolescentes apresentaram maiores escores que as meninas adolescentes, embora em geral o nível de atividade física tenha um nível médio-baixo em ambos sexos Outra conclusão a ser observada é que meninos e meninas têm poucos problemas relacionados a videogames e que a maioria deles não cumpre semanalmente as recomendações mínimas de atividade física, o que pode ter um impacto negativo em sua saúde física e psicológica

Efecto inmediato de la auto-liberación miofascial en la superficie plantar sobre la musculatura isquiosural en futbolistas

Adhesions in certain muscle areas generate tension in other muscles of the same muscle chain. The aim of the study is to test the immediate effect of the “Self-myofascial release” (SMR) with the golf ball technique on the plantar fascia in federated sportsmen of "Football 11" (FU) and "Futsal" (FS) and its influence on hamstring musculature. Besides, the differences between each modality have been analysed. The design is of the longitudinal experimental type, with a sample of 20 federated sportsmen. The results show significant improvement in the length reached in the “Sit and Reach Test” (SRT) after the SMR between "Control Group" (GC) and "Experimental Group"(GE). There are no significant differences between modalities. It is therefore concluded that there is an immediate effect of SMR with the golf ball technique on the plantar fascia over the hamstring muscle. There are no significant differences between modalities.Las adherencias en ciertas zonas musculares generan tensiones en otras musculaturas de la misma cadena muscular. El objetivo del estudio es probar el efecto inmediato de la “Auto-liberación Miofascial” (SMR) con la técnica de pelota de golf en la fascia plantar en deportistas federados de “Fútbol 11” (FU) y “Fútbol Sala” (FS) y su incidencia sobre la musculatura isquiosural. Además, se analizó las diferencias entre cada modalidad. El diseño es de tipo experimental longitudinal, con una muestra de 20 deportistas federados. Los resultados muestran una mejora en la longitud alcanzada en el “Test Sit and Reach” (SRT) de forma significativa la SMR entre “Grupo Control” (GC) y “Grupo Experimental” (GE). Entre modalidades no se aprecian diferencias significativas. Se concluye que existe un efecto inmediato de la SMR con la técnica de pelota de golf en la fascia plantar sobre la musculatura isquiosural. No existiendo diferencias significativas entre modalidades

Portuguese recommendations for the use of biological therapies in patients with psoriatic arthritis - 2015 update

OBJECTIVE: To update recommendationsforthe treatment of psoriatic arthritis with biological therapies, endorsed by the Portuguese Society of Rheumatology (SPR). METHODS: These treatment recommendations were formulated by Portuguese rheumatologists based on literature evidence and consensus opinion. At a national meeting the 16 recommendations included in this document were discussed and updated. The level of agreement among Portuguese Rheumatologists was assessed using an online survey. A draft of the full text of the recommendations was then circulated and suggestions were incorporated. A final version was again circulated before publication. RESULTS: A consensus was achieved regarding the initiation, assessment of response and switching biological therapies in patients with psoriatic arthritis (PsA). Specific recommendations were developed for several disease domains: peripheral arthritis, axial disease, enthesitis and dactylitis. CONCLUSION: These recommendations may be used for guidance in deciding which patients with PsA should be treated with biological therapies. They cover a rapidly evolving area oftherapeutic intervention.Asmore evidence becomes available and more biological therapies are licensed, these recommendations will have to be updated