1,429 research outputs found

    Low water supply differentially affects the growth, yield and mineral profile of kabuli and desi chickpeas (cicer arietinum)

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    The climatic events predicted to increase in intensity and frequency in the near future, including drought, may influence the quality and productivity of several important crops for human nutrition, such as legumes. Herein, two chickpea genotypes (Cicer arietinum) were analysed for their resilience to low water supply: a commercial white chickpea (kabuli), and a black chickpea (desi) with marginal production in occidental countries. Plants were grown under four levels of water supplies (90, 75, 50 and 25% of field capacity), and biometric variables (root, shoot, pods and seeds), proxies of plant fitness (water content and oxidative stress) and the seed nutritional profile (protein and mineral concentrations) were analysed at plant maturity. Results show that water content in shoots and roots decreased with decreasing water supplies, with kabuli plants generally having higher water content in shoots and desi in roots. Shoot length was significantly higher in kabuli compared to desi, while root length increased up to 11% in both species with decreasing water supplies. The root-to-shoot ratio was higher in kabuli and increased with decreasing water supply, being negatively correlated with the number of pods and seeds per plant. Lipid peroxidation increased with decreasing water supply, having slight positive correlations with plant growth parameters while being negatively correlated with plant productivity. No significant effects of plant genotype and water supply were observed on seed K, Ca, and protein, but desi was able to sustain higher P, Mg, Zn, Fe, Mn and B than kabuli, including at lower water supplies. Results suggest that water stress negatively impacts plant growth and productivity and that the two chickpea genotypes have distinct biomass and water allocation strategies to cope with low water supply. These findings may be useful in strategies for improving the productivity and nutritional profile of chickpea crops under water-limited conditions.info:eu-repo/semantics/publishedVersio

    Methodologies and Applications Review

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    Funding Information: The Authors acknowledge Fundação para a Ciência e a Tecnologia (FCT-MCTES) for its financial support via the project UIDB/00667/2020 (UNIDEMI). Pedro M. Ferreira also acknowledges FCT-MCTES for funding the PhD grant UI/BD/151055/2021. Publisher Copyright: © 2022 by the authors.Sensing Technology (ST) plays a key role in Structural Health-Monitoring (SHM) systems. ST focuses on developing sensors, sensory systems, or smart materials that monitor a wide variety of materials’ properties aiming to create smart structures and smart materials, using Embedded Sensors (ESs), and enabling continuous and permanent measurements of their structural integrity. The integration of ESs is limited to the processing technology used to embed the sensor due to its high-temperature sensitivity and the possibility of damage during its insertion into the structure. In addition, the technological process selection is dependent on the base material’s composition, which comprises either metallic or composite parts. The selection of smart sensors or the technology underlying them is fundamental to the monitoring mode. This paper presents a critical review of the fundaments and applications of sensing technologies for SHM systems employing ESs, focusing on their actual developments and innovation, as well as analysing the challenges that these technologies present, in order to build a path that allows for a connected world through distributed measurement systems.publishersversionpublishe

    Granting Sensorial Properties to Metal Parts through Friction Stir Processing

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    The authors would like also to thank to Micronsense-Metrologia Industrial (Leiria, Portugal) for the μCT analysis. The authors would also like to thank Prof. Catarina Santos for granting access to the MicroLab - Electron Microscopy Laboratory (Instituto Superior Técnico) for the SEM analyses.Structural Health Monitoring systems assess the part's current condition. This can be performed with a monitoring system comprising sensors, on the surface or embedded, in the monitored parts. However, surface sensors are subject to damage, and embedding the sensors may result in a weakened part. An innovative Self-Sensing Material and its manufacturing process were developed and are presented herein. As proof of concept, Barium Titanate particles were introduced and dispersed into an AA5083-H111 part by Friction Stir Processing (FSP). The particles’ distribution and concentration was evaluated by a set of characterization techniques, demonstrating that greater concentrations, grant enhanced sensitivity to the material. The use of FSP and the embedded particles improved the part’s mechanical behaviour in the processed zone. The sensorial properties were assessed and the response to a set of dynamic loads was measured, being coherent with the solicitations provided. The developed self-sensing material revealed an electrical sensitivity of 12.0 × 10-4 uV/MPa.publishersversionpublishe

    Ab initio study of the properties of Ti1-x-ySixAlyN solid solution

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    We have studied the electronic, structural, and elastic properties of Ti1-x-ySixAlyN metastable phase, using first principles calculations based on the density functional theory. These calculations provide the lattice parameter, density of states, cohesive energy, formation energy and elastic constants, when Si and Al atoms replace Ti in the TiN lattice. The calculated values of lattice parameters and elastic constants are generally in good agreement with experiments and compare well with other theoretical results. We show that the trend followed by cohesive energy, formation energy, elastic constants is related to the electronic properties and bonding characteristics of these compounds

    Influence of uniform temperature variations on hybrid bonded joints with a circular or tubular cross-sectional area

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    Funding Information: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Hugo C. Biscaia reports financial support was provided by Foundation for Science and Technology. Marta S. Carvalho reports financial support was provided by Foundation for Science and Technology. Ana P. Martins reports financial support was provided by Foundation for Science and Technology. Publisher Copyright: © 2023 The AuthorsThe use of lightweight structures is a current concern in several engineering domains. To obtain such types of structures, the bonding technique using Carbon Fibre-Reinforced Polymers (CFRP) has been most recently considered a primary option. If CFRP is known to have a high strength-to-weight ratio or high corrosion resistance, the bonding technique does not need to add other fixation components and it also prevents stress concentrations. However, when combined with, e.g. a metallic surface, the high difference between the thermal expansion coefficient of the CFRP composite and the metallic material may raise some issues when the adhesively bonded structure is subjected to thermal loading. Therefore, the present work presents an analytical model that facilitates the comprehension of the impact of temperature on a hybrid bonded joint with a circular or tubular cross-sectional area. The full debonding process of a double but bonded joint with a regular curvature is discussed thoroughly. Due to the susceptibility of current adhesives to lose their mechanical properties for relatively high temperatures, the vitreous transition temperature of the adhesives and their influence on the local adhesive model is considered in a deeper analysis. The Finite Element Method (FEM) was used to validate all the derived analytical equations, which were achieved due to the close predictions obtained from both ways, i.e. from the numerical simulations and the proposed closed-form solutions.publishersversionpublishe

    Dual role of copper on the reactivity of activated carbons from coal and lignocellulosic precursors

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    The synthesis of copper-doped activated carbons from different origin (i.e., lignocellulosic and bituminous coal) by a wet impregnation and low temperature calcination procedure has been explored, as well as the role of copper particles on the physicochemical and structural features of the resulting materials. The textural characterization and isothermal reactivity analysis of the pristine and doped activated carbons have shown that the role of copper during the calcination step strongly depended on the nature of the carbon matrix. Copper impregnation of a coal-derived activated carbon catalyzed the air gasification of the material at a very low temperature (i.e., 325 °C), bringing about the development of microporosity on the doped carbon. In contrast, when copper was immobilized on a lignocellulose-derived activated carbon, the metallic species act as combustion retardant during the calcination step, protecting the carbon matrix during the catalytic gasification. In both cases, the resulting materials displayed a homogenous distribution of copper within the carbon matrix, while preserving large textural properties.The authors thank the Spanish MICINN for financial support (projects CTM2008-01956/TECNO and Acción Integrada AIB2010PT-00209). MH thanks CSIC for a postdoctoral contract. MA thanks FCT for her PhD fellowship (SFRH/BD/71673/2010). The authors also thank Cordex for kindly providing the sisal residues.Peer reviewe

    Reputação corporativa: o desafio da análise

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    Although corporate reputation has been studied for several decades, its interest has intensified only from the 1990s onwards. With the growing market competitiveness firms need to take advantage of their full assets in order to add value to their customers, and the reputation is one of them. Accordingly, it was decided to review the literature that analyses reputation models and the influence of key stakeholders. Given the complexity of the issue, it was also decided to complement the analysis of models with a review of key variables / constructs that influence corporate reputation.Embora a reputação corporativa tem sido objeto de estudo desde há algumas décadas, só a partir dos anos 90 é que o interesse pela temática se intensificou. Com a competitividade de mercado as empresas precisam de todos os ativos que lhes possam acrescentar valor, sendo a reputação um deles. Assim, foi decidido fazer uma revisão à literatura que explana os modelos de avaliação da reputação e a influência dos principais stakeholders. Dada a complexidade do tema, foi igualmente decidido complementar a análise dos modelos com uma revisão das principais variáveis/constructos que se relacionam com a reputação corporativa

    Effect of the irradiation wavelength on the performance of nanoporous carbon as an additive to TiO2

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    We report the dependence of the photochemical activity of titania/carbon hybrid catalysts toward the degradation of phenol from solution using polychromatic light and filters. In all cases larger photooxidative efficiencies were obtained using light at 200 nm 200 nm. The photocatalytic runs carried out with the nonporous carbon alone confirmed a certain level of intrinsic photoactivity under both irradiation conditions. Nevertheless, a clear deactivation was evident after 60 min of irradiation suggesting that the photoactive sites in the carbon are either consumed or deactivated in the course of the reaction. The composition of the catalyst and the illumination conditions also have a strong effect on the nature of the degradation intermediates, with a marked regioselectivity toward ortho-substitution at high energy photons and when the carbon component is added to the catalyst composition.The authors thank Cordex (Portugal) for kindly supplying sisal. The financial support of the pluriannual funding to CQB (UID/MULTI/00612/2013), and MINECO (CTM2014/56770-R, AIB2010-PT00209) is also acknowledged. MAA and ASM thank FCT for their PhD (SFRH/BD/71673/2010) and Post-Doc (SFRH/BPD/86693/2012) fellowships, respectively. RJC thanks PCTI Asturias Fondos Feder for her Severo Ochoa fellowship. The authors thank Dr. Matos for fruitful discussion.Peer reviewe

    numerical modelling and validation

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    Publisher Copyright: © 2023 The Author(s)This study investigates the Non-Destructive Testing (NDT) inspection of 3D-printed fibre-reinforced polymers, comparing the conventional Active Transient Thermography (ATT) technique with a novel variant known as Double Active Transient Thermography (DATT). Finite element models for the simulation of both inspection techniques are validated by evaluating two statistical measures to correlate the numerical results with the experimental responses. The thermal contrast obtained with DATT was approximately twice the one obtained with ATT, for all tested samples. Numerical models allowed an insight evaluation of the heat dissipation along the thickness of the specimens, specifically around the fibres and the defects. These validated numerical models evidenced a relevant tool to predict the results of thermal contrast and to optimize the inspection parameters.publishersversionpublishe
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