1,497 research outputs found

    Self-Healing Polymer Nanocomposite Materials by Joule Effect

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    Nowadays, the self-healing approach in materials science mainly relies on functionalized polymers used as matrices in nanocomposites. Through different physicochemical pathways and stimuli, these materials can undergo self-repairing mechanisms that represent a great advantage to prolonging materials service-life, thus avoiding early disposal. Particularly, the use of the Joule effect as an external stimulus for self-healing in conductive nanocomposites is under-reported in the literature. However, it is of particular importance because it incorporates nanofillers with tunable features thus producing multifunctional materials. The aim of this review is the comprehensive analysis of conductive polymer nanocomposites presenting reversible dynamic bonds and their energetical activation to perform self-healing through the Joule effect

    Ler no ecrã: contributo para uma reflexão sobre estratégias de ensino da leitura na aula de Português

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    Resumo: A Escola assume, hoje, um papel cada vez mais ativo na formação dos (ciber)leitores, sendo chamada a reconfigurar um conjunto pré-existente de práticas em literacia onde predomina o texto impresso para um universo digital complexo, no qual o ecrã tem primazia. Assim, neste artigo procuraremos: (1) reforçar o modo como novas práticas em literacia emergem em permanência na nossa sociedade, repercutindo-se no percurso dos leitores em formação; (2) apontar para o modo como a leitura no ecrã de textos diversificados influencia a compreensão leitora, daí retirando ilações no que concerne à construção do percurso do leitor; (3) caracterizar a forma como a leitura online requer o desenvolvimento de um conjunto amplo de estratégias por parte do leitor, para que possa usufruir plenamente do prazer de ler em contexto escolar e extra-escolar. Finalmente, reflectimos criticamente sobre os desafios colocados hoje à Escola, relativamente à implementação e consolidação de percursos de leitura que estejam na base do exercício hodierno da cidadania

    Advanced hydrogels for treatment of diabetes

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    Diabetes mellitus is a chronic disease characterized by high levels of glucose in the blood, which leads to metabolic disorders with severe consequences. Today, there is no cure for diabetes. The current management for diabetes and derived medical conditions, such as hyperglycemia, cardiovascular diseases or diabetic foot ulcer, includes life style changes and hypoglycemia based therapy, which do not fully restore euglycemia or the functionality of damaged tissues in patients. This encourages scientists to work outside their boundaries to develop routes that can potentially tackle such metabolic disorders. In this regard, acellular and cellular approaches have represented an alternative for diabetics, although such treatments still face shortcomings related to limited effectiveness and immunogenicity. The advent of biomaterials has brought significant improvements for such approaches, and three-dimensional extracellular matrix analogous, such as hydrogels, have played a key role in this regard. Advanced hydrogels are being developed to monitor high blood glucose levels and release insulin, as well as serve as a therapeutic technology. Herein, the state of the art in advanced hydrogels for improving treatment of diabetes, from laboratory technology to commercial products approved by drug safety regulatory authorities, will be concisely summarized and discussed. [Abstract copyright: This article is protected by copyright. All rights reserved.

    Mercados municipales de Zapopan

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    Documento final del Proyecto de Aplicación Profesional en el que se presenta una investigación realizada en tres mercados del ayuntamiento de Zapopan: San Isidro, Francisco Sarabia y Tesistán. El objetivo de la investigación fue identificar las problemáticas, hacer propuestas y colaborar en la planeación de estrategias para mejorar las condiciones de los mercados y lograr un impacto positivo que se vea reflejado en las ventas. Para la investigación, se visitaron los mercados y se aplicaron encuestas a los locatarios, consumidores y administradores. La muestra que se usó para sacar el número de encuestas fue infinita con un nivel de confianza del 90 por ciento y un índice de error del 5 por ciento. En este proyecto trabajaron alumnos de las licenciaturas en Mercadotecnia, Administración de Empresas y Administración Financiera.ITESO, A.C

    Volcanic Emissions and Atmospheric Pollution: A Study of Nanoparticles

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    The influence of emissions of an active volcano on the composition of nanoparticles and ultrafine road dust was identified in an urban area of the Andes. Although many cities are close to active volcanoes, few studies have evaluated their influence in road dust composition. Air quality in urban areas is significantly affected by non-exhaust emissions (e.g. road dust, brake wear, tire wear), however, natural sources such as volcanoes also impact the chemical composition of the particles. In this study, elements from volcanic emissions such as Si \u3e Al \u3e Fe \u3e Ca \u3e K \u3e Mg, and Si—Al with K were identified as complex hydrates. Similarly, As, Hg, Cd, Pb, As, H, Cd, Pb, V, and salammoniac were observed in nanoparticles and ultrafine material. Mineral composition was detected in the order of quartz\u3e mullite\u3e calcite\u3e kaolinite\u3e illite\u3e goethite\u3e magnetite\u3e zircon\u3e monazite, in addition to salammoniac, a tracer of volcanic sources. The foregoing analysis reflects the importance of carrying out more studies relating the influence of volcanic emissions in road dust in order to protect human health. The road dust load (RD10) ranged between 0.8 and 26.8 mg m−2 in the city

    Volcanic emissions and atmospheric pollution: a study of nanoparticles

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    The influence of emissions of an active volcano on the composition of nanoparticles and ultrafine road dust was identified in an urban area of the Andes. Although many cities are close to active volcanoes, few studies have evaluated their influence in road dust composition. Air quality in urban areas is significantly affected by non-exhaust emissions (e.g. road dust, brake wear, tire wear), however, natural sources such as volcanoes also impact the chemical composition of the particles. In this study, elements from volcanic emissions such as Si > Al > Fe > Ca > K > Mg, and Si Al with K were identified as complex hydrates. Similarly, As, Hg, Cd, Pb, As, H, Cd, Pb, V, and salammoniac were observed in nanoparticles and ultrafine material. Mineral composition was detected in the order of quartz> mullite> calcite> kaolinite> illite> goethite> magnetite> zircon> monazite, in addition to salammoniac, a tracer of volcanic sources. The foregoing analysis reflects the importance of carrying out more studies relating the influence of volcanic emissions in road dust in order to protect human health. The road dust load (RD10) ranged between 0.8 and 26.8 mg m−2 in the city

    Prebiotics, Probiotics, Synbiotics and Functional Foods in Control and Treatment of Type II Diabetes Mellitus and Colorectal Cancer

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    Prebiotics, probiotics and synbiotics are components that enhance human health by several mechanisms. Patients suffering from type II diabetes mellitus (T2DM) and colorectal cancer have seen benefits when treated with a prebiotic, probiotic or synbiotic therapy. These benefits include the improvement of their lipid profile, oxidative stress status, as well as the modulation of the inflammatory and immune responses. The associated benefits of prebiotic, probiotic or synbiotic functional foods have been studied, showing promising results into the prevention or control of diabetes and colorectal cancer. This novelty research provides new evidence that the use of functional foods along with medical therapy could be used to further enhance patient’s health

    Carotenoid skin ornaments as flexible indicators of male foraging behavior in a marine predator: Variation among Mexican colonies of brown booby ( Sula leucogaster )

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    Carotenoid-dependent ornaments can reflect animals’ diet and foraging behaviors. However, this association should be spatially flexible and variable among populations to account for geographic variation in optimal foraging behaviors. We tested this hypothesis using populations of a marine predator (the brown booby, Sula leucogaster) that forage across a gradient in ocean depth in and near the Gulf of California. Specifically, we quantified green chroma for two skin traits (foot and gular color) and their relationship to foraging location and diet of males, as measured via global positioning system tracking and stable carbon isotope analysis of blood plasma. Our three focal colonies varied in which foraging attributes were linked to carotenoid-rich ornaments. For gular skin, our data showed a shift from a benthic prey-green skin association in the shallow waters in the north to a pelagic prey-green skin association in the deepest waters to the south. Mean foraging trip duration and distance of foraging site from coast also predicted skin coloration in some colonies. Finally, brown booby colonies varied in which trait (foot versus gular skin color) was associated with foraging metrics. Overall, our results indicate that male ornaments reflect quality of diet and foraging–information that may help females select mates who are adapted to local foraging conditions and therefore, are likely to provide better parental care. More broadly, our results stress that diet-dependent ornaments are closely linked to animals’ environments and that we cannot assume ornaments or ornament signal content are ubiquitous within species, even when ornaments appear similar among populations

    Oxidative Stress and Parkinson’s Disease: Effects on Environmental Toxicology

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    Epidemiological studies have found an increased risk of Parkinson’s disease (PD) with environmental factors such as exposure to substances derived from industrial processes, use of agrochemicals, or living in a rural environment. The hypothesis that certain environmental toxins could be the source of the EP is supported by the discovery that chemicals such as herbicides paraquat, diquat, and the fungicide maneb are selectively toxic in nigrostriatal dopaminergic neurons. Also, one of the insecticides produced by plants, such as rotenone, and by-product of the synthesis of synthetic heroin MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) can be reproduced in animal models where neurochemicals, histopathological, and clinical characteristic of PD can be found. Interestingly, there are similarities in the chemical structure of paraquat and MPTP. Recent evidence exhibited that inflammation and oxidative stress play an essential role in the development of PD. So, in our laboratory we found that in an animal model melatonin decreases the products of lipid oxidation, nitric oxide metabolites, and the activity of cyclooxygenase 2, which are induced by an intraperitoneal injection of MPTP. This suggests that the neuroprotective effects of melatonin are partially attributed to its antioxidant scavenging and anti-inflammatory action
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