Search

Studies that aim to produce flexible films of composite materials based on ionomers-PZT, and volume fractions lower than 10% PZT, in order to monitor damage in aeronautical structures are seldom investigated. The growing emphasis on the use of polymers capable of self-healing after damage or activation by heating has motivated the application of self-healing ionomers as polymeric matrices in composites with piezoelectric particles aiming to monitor damage. Flexible composite films were developed based on the self-healing polymer matrix Surlyn® 8940 ionomer (DuPontTM—Wilmington, DE, USA) and PZT particles (connectivity 2–3) in volume fractions of 1, 3, 5 and 7%, with thickness around 50–100 µm. The choice of PZT volume fractions followed the preliminary requirement that establishes a final density, which is lower or at least close to the density of the materials used in aeronautical structures. Since the application of composites based on epoxy resin/carbon fibers has been increasing in the aeronautical segment, this material (with density lower than 1500 kg/m3) was chosen as a reference for the present work. Thus, due to self-healing (a characteristic of the matrix Surlyn® 8940) combined with recyclability, high flexibility and low thickness, the flexible composite films showed advantages to be applied on aeronautical structures, which present complex geometries and low-density materials. The manufactured films were characterized by SEM, XRD, DMA and mechanical tensile tests. The results were discussed mainly in terms of the volume fraction of PZT. X-ray diffraction patterns showed coexistent rhombohedral and tetragonal phases in the PZT particles-dispersed composite, which can potentialize the alignment of ferroelectric domains during polarization under strong electrical field, enhancing dielectric and piezoelectric properties toward sensing applications. DMA and tensile testing results demonstrated that the addition of PZT particles did not impair either dynamic or quasi-static mechanical performance of the flexible composite films. It was concluded that the PZT volume fraction should be lower than 3% because, for higher values, the molecular mobility of the polymer would suffer significant reductions. These findings, combined with the high flexibility and low density of the ceramic particle-filled thermoplastic polymer, render the developed flexible composite film a very promising candidate for strain and damage sensing in aeronautical structures. [ABSTRACT FROM AUTHOR]

The worldwide energy scarcity arising from the massive consumption of nonrenewable energy sources raised a global awareness of the need for cleaner and affordable energy solutions to mitigate climate change and ensure the world sustainable development. The rise of the Internet of Things and the fast growth of the groundbreaking market of wearable electronics boosted a major quest for self-powered technologies merging energy harvesting and energy storage functionalities to meet the demands of a myriad of market segments, such as healthcare, transportation, defense and sports. Thermoelectric devices are a green energy harvesting solution for wearable electronics since they harness the low-grade waste heat from ubiquitous thermal energy sources and convert it into electrical energy. However, these systems generate electrical energy in an intermittent manner, depend on the local heat release availability and require an additional unit to store energy. Flexible and wearable supercapacitors are a safe and eco-friendly energy storage solution to power wearables, offering advantages of security, longer cycle life, higher power density and faster charging over batteries. However, an additional unit that generates energy or that is able to charge the storage device is required. More recently, a new class of all-in-one thermally-chargeable supercapacitors blossomed to meet the requirements of the next generation of autonomous wearable electronics and ensure an endurable energy supply. This self-chargeable hybrid technology combines the functionalities of thermal energy harvesting and supercapacitive energy storage in a single multitasking device. In this Perspective, the advances in the burgeoning field of all-in-one thermally-chargeable supercapacitors for flexible/wearable applications will be critically examined, ranging from their structure and working principle to the rational design of the composing materials and of tailor-made architectures. It will start by introducing the foundations of single flexible/wearable thermoelectric generators and supercapacitors and will evolve into the pioneering venture of fully-integrated thermal energy harvesting/storage systems. It will end by highlighting the current bottlenecks and future pathways for advancing the development of this sophisticated smart technology. [ABSTRACT FROM AUTHOR]

Carmines (E120) are used worldwide as natural food colouring agents of animal origin, with a widespread application, including yoghurts. Despite being considered safe for human health, carmines are known to cause allergic reactions. Our goal was to evaluate the presence of carmines in different yoghurts with a label declaration of E120, purchased in Portugal, and, for the first time, to assess the human risk. The analytical methodology, recommended by JECFA, was based on acid hydrolysis of the samples followed by spectrophotometric UV-Vis analysis at 494 nm. This methodology allowed for a limit of quantification (LOQ) of 39.0 mg/kg and recovery rates higher than 97.7%. All the samples had carmines at levels above the LOQ, ranging between 43.8 and 193.8 mg/kg, with an average of 125.2 ± 34.5 mg/kg. In total, 8 (26.7%) samples exceeded the European Union (EU) maximum permitted level (MPL) established for carmines in this foodstuff, 150 mg/kg. Solid yoghurts presented higher average levels, 137.2 mg/kg, when compared to liquid samples, 107.2 mg/kg, with a significant statistical difference (p= 0.0236) being observed. No significant statistical difference was observed between white and private labels, whose average levels were very similar, 125.4 vs 125 mg/kg, respectively. Although some samples were above the allowable values, the estimated daily intake (EDI), designed for the different scenarios of different yoghurt types, did not exceed the established ADI, 5 mg/kg bw/day. According to the obtained results, carmine ingestion through the consumption of yoghurt poses low risk to the Portuguese consumers. However, children were the most vulnerable population group with a calculated risk value of up to 10% considering the mean content scenario. These first findings point out the need to reinforce surveillance programmes and monitoring studies, contributing to an increased awareness regarding carmine exposure, however it must be emphasised that yoghurt has evident nutritional benefits depending on a healthful consumer choice. [ABSTRACT FROM AUTHOR]

Human biomonitoring (HBM) data provide information on total exposure regardless of the route and sources of exposure. HBM studies have been applied to quantify human exposure to contaminants and environmental/occupational pollutants by determining the parent compounds, their metabolites or even their reaction products in biological matrices. HBM studies performed among the Portuguese population are disperse and limited. To overcome this knowledge gap, this review gathers, for the first time, the published Portuguese HBM information concerning polycyclic aromatic hydrocarbons (PAHs), metals, metalloids, and pesticides concentrations detected in the urine, serum, milk, hair, and nails of different groups of the Portuguese population. This integrative insight of available HBM data allows the analysis of the main determinants and patterns of exposure of the Portuguese population to these selected hazardous compounds, as well as assessment of the potential health risks. Identification of the main difficulties and challenges of HBM through analysis of the enrolled studies was also an aim. Ultimately, this study aimed to support national and European policies promoting human health and summarizes the most important outcomes and lessons learned through the HBM studies carried out in Portugal. [ABSTRACT FROM AUTHOR]

Human biomonitoring (HBM) data provide information on total exposure regardless of the route and sources of exposure. HBM studies have been applied to quantify human exposure to contaminants and environmental/occupational pollutants by means of determining the parent compounds, their metabolites, or even their reaction products in biological matrices. HBM studies performed among the Portuguese population are dispersed and limited. Thus, to overcome this knowledge gap, this work reviews the published Portuguese HBM information concerning mycotoxins detected in the urine, serum, milk, hair, and nails of different groups of the Portuguese population. This integrative approach to the available HBM data allows us to analyze the main determinants and patterns of exposure of the Portuguese population to the selected hazardous compounds, as well as to assess the potential health risks. We also aimed to identify the main difficulties and challenges of HBM through the analysis of the enrolled studies. Ultimately, this study aims to support national and European policies in promoting human health by summarizing the most important outcomes and lessons learned through the HBM studies carried out in Portugal. [ABSTRACT FROM AUTHOR]

Liposome-like nanoarchitectures containing manganese ferrite nanoparticles covered or decorated with gold were developed for application in dual cancer therapy, combining chemotherapy and photothermia. The magnetic/plasmonic nanoparticles were characterized using XRD, UV/Visible absorption, HR-TEM, and SQUID, exhibiting superparamagnetic behavior at room temperature. The average size of the gold-decorated nanoparticles was 26.7 nm for MnFe2O4 with 5–7 nm gold nanospheres. The average size of the core/shell nanoparticles was 28.8 nm for the magnetic core and around 4 nm for the gold shell. Two new potential antitumor fluorescent drugs, tricyclic lactones derivatives of thienopyridine, were loaded in these nanosystems with very high encapsulation efficiencies (higher than 98%). Assays in human tumor cell lines demonstrate that the nanocarriers do not release the antitumor compounds in the absence of irradiation. Moreover, the nanosystems do not cause any effect on the growth of primary (non-tumor) cells (with or without irradiation). The drug-loaded systems containing the core/shell magnetic/plasmonic nanoparticles efficiently inhibit the growth of tumor cells when irradiated with red light, making them suitable for a triggered release promoted by irradiation. [ABSTRACT FROM AUTHOR]

Water pollution is a major environmental challenge. Due to the inefficiency of conventional wastewater treatment plants in degrading many organic complex compounds, these recalcitrant pollutants end up in rivers, lakes, oceans and other bodies of water, affecting the environment and human health. Semiconductor photocatalysis is considered an efficient complement to conventional methods, and the use of various nanomaterials for this purpose has been widely explored, with a particular focus on improving their activity under visible light. This work focuses on developing magnetic and photoactive zinc/magnesium mixed ferrites (Zn 0.5 Mg 0.5 Fe 2 O 4 ) by sol-gel and solvothermal synthesis methods, which are two of the most important and efficient methods used for the synthesis of ferrite nanoparticles. The nanoparticles (NPs) synthesized by the sol-gel method exhibited an average size of 14.7 nm, while those synthesized by the solvothermal method had an average size of 17.4 nm. Both types possessed a predominantly cubic structure and demonstrated superparamagnetic behavior, reaching a magnetization saturation value of 60.2 emu g -1 . Due to the high recombination rate of electrons/holes, which is an intrinsic feature of ferrites, surface functionalization with silver was carried out to enhance charge separation. The results demonstrated a strong influence of adsorption and of the deposition of silver. Several optimization steps were performed during synthesis, allowing us to create efficient catalysts, as proved by the almost full removal of the dye malachite green attaining 95.0% (at a rate constant of 0.091 min -1 ) and 87.6% (at a rate constant of 0.017 min -1 ) using NPs obtained by the sol-gel and solvothermal methods, respectively. Adsorption in the dark accounted for 89.2% of the dye removal for nanoparticles prepared by sol-gel and 82.8% for the ones obtained by the solvothermal method. These results make mixed zinc/magnesium ferrites highly promising for potential industrial application in effluent photoremediation using visible light.

The Azorean dairy industry is based on a semi-intensive model. Due to the few storage facilities and the large climatic fluctuations that characterize the Azores, the complete feed mixture (total mixed ration - TMR) is susceptible to the proliferation of a variety of fungi and mycotoxin contamination. Thus, chronic ingestion of these xenobiotics may lead to increased susceptibility to disease, loss of reproductive performance and, in the case of dairy cattle, decreased productivity and quality of milk produced. Since it is impossible to eliminate completely the presence of mycotoxins, it is essential to ensure the implementation of strategies to reduce their concentration in products intended for food and feed, as well as to monitor and control the levels present in food. This study aimed to evaluate the occurrence zearalenone (ZEA) in feed (TMR) in four dairy cattle farms on the Azorean Island of São Miguel and relate it to the occurrence of this mycotoxin in the milk produced, by associating several production and health indicators translated by the monthly milk contrast. To this end, the monthly milk contrast data, the determination of ZEA in the ingested feed and the (individual) milk samples from the four farms included in the study were used. Eighty-three (98.8%) of the milk samples under study had detectable ZEA levels (1.56 ± 1.36 μg/L), higher than reported in previous similar studies. Although ZEA concentration was not significantly associated with any production indicator analyzed (days in milk, age at calving, milk yield, protein content, butyrate content, somatic cell concentration and urea), it was found that the production regime and type of feed management is a major factor in the exposure of animals to high mycotoxin contents. Further studies are recommended to ensure continued monitoring and reduction of the risk associated with exposure of animals and humans to ZEA., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Studies that aim to produce flexible films of composite materials based on ionomers-PZT, and volume fractions lower than 10% PZT, in order to monitor damage in aeronautical structures are seldom investigated. The growing emphasis on the use of polymers capable of self-healing after damage or activation by heating has motivated the application of self-healing ionomers as polymeric matrices in composites with piezoelectric particles aiming to monitor damage. Flexible composite films were developed based on the self-healing polymer matrix Surlyn ® 8940 ionomer (DuPont TM -Wilmington, DE, USA) and PZT particles (connectivity 2-3) in volume fractions of 1, 3, 5 and 7%, with thickness around 50-100 µm. The choice of PZT volume fractions followed the preliminary requirement that establishes a final density, which is lower or at least close to the density of the materials used in aeronautical structures. Since the application of composites based on epoxy resin/carbon fibers has been increasing in the aeronautical segment, this material (with density lower than 1500 kg/m 3 ) was chosen as a reference for the present work. Thus, due to self-healing (a characteristic of the matrix Surlyn ® 8940) combined with recyclability, high flexibility and low thickness, the flexible composite films showed advantages to be applied on aeronautical structures, which present complex geometries and low-density materials. The manufactured films were characterized by SEM, XRD, DMA and mechanical tensile tests. The results were discussed mainly in terms of the volume fraction of PZT. X-ray diffraction patterns showed coexistent rhombohedral and tetragonal phases in the PZT particles-dispersed composite, which can potentialize the alignment of ferroelectric domains during polarization under strong electrical field, enhancing dielectric and piezoelectric properties toward sensing applications. DMA and tensile testing results demonstrated that the addition of PZT particles did not impair either dynamic or quasi-static mechanical performance of the flexible composite films. It was concluded that the PZT volume fraction should be lower than 3% because, for higher values, the molecular mobility of the polymer would suffer significant reductions. These findings, combined with the high flexibility and low density of the ceramic particle-filled thermoplastic polymer, render the developed flexible composite film a very promising candidate for strain and damage sensing in aeronautical structures.