Silver nanoparticles flow in an aquatic trophic chain

Silver nanoparticles (AgNP) have been produced and applied in a variety of products ranging from personal care products to food package containers, clothing and medicine utilities. The antimicrobial function of AgNP makes it very useful to be applied for such purposes. Silver (Ag) is a non-essential metal for organisms, and it has been historically present in the environment at low concentrations. Those concentrations of silver increased in the last century due to the use of Ag in the photographic industry and lately are expected to increase due to the use of AgNPs in consumer products. The presence of AgNP in the aquatic environment may pose a risk for aquatic species, and the effects can vary from lethal to sublethal effects. Moreover, the contact of aquatic organisms with AgNP may not cause immediately the death of individuals but it can be accumulated inside the animals and consequently transferred within the food chain. Considering this, the objective of this work was to study the transfer of silver nanoparticles in comparison to silver ions, which was used as silver nitrate, within an aquatic food chain model. To achieve this goal, this study was divided into four steps: the toxicity assessment of AgNP and AgNO3 to aquatic test-species, the bioaccumulation assessment of AgNP and AgNO3 by Pseudokirchneriella subcapitata and Daphnia magna under different exposure scenarios, and finally the evaluation of the trophic transfer of Ag through an experimental design that included the goldfish Carassius auratus in a model trophic chain in which all the species were exposed to the worse-case scenario. We observed that the bioconcentration of Ag by P. subcapitata is mainly driven by ionic silver, and that algae cannot internalize these AgNPs, but it does internalizes dissolved Ag. Daphnia magna was exposed to AgNP and AgNO3 through different exposure routes: water, food and both water and food. The worse-case scenario for Daphnia Ag bioaccumulation was by the joint exposure of contaminated water and food, showing that Ag body burdens were higher for AgNPs than for AgNO3. Finally, by exposing C. auratus for 10 days through contaminated water and food (supplied as D. magna), with another 7 days of depuration phase, it was concluded that the 10 days of exposure were not enough for fish to reach a plateau on Ag internal concentration, and neither the 7 days of elimination were sufficient to cause total depuration of the accumulated Ag. Moreover, a higher concentration of Ag was found in the intestine of fish when compared with other organs, and the elimination rate constant of AgNP in the intestine was very low. Although a potential for trophic transfer of AgNP cannot be suggested based in the data acquired in this study, there is still a potential environmental risk for aquatic species.

Exposições museológicas: a moda por narrativas, experiências e conexões

Este estudo apresenta o universo patrimonial pela perspetiva da acessibilidade pública conferida por instituições museológicas. Consiste em exploração e análise das informações e experiências proporcionadas por museus no âmbito da cultura material indumentária e de moda. O foco desta abordagem são as exposições presenciais e os websites institucionais, com ênfase à acessibilidade aos catálogos de coleções. Pela perspectiva do designer como antropólogo neste estudo – com base em estudos de caso e outros dados coletados – são apresentadas ferramentas comparativas da realidade atual e propostas para a disseminação mais alargada, diversificada e especializada das informações cultura material e imaterial de moda. Duas hipóteses orientaram esta tese: - A noção de que as exposições de artefatos de traje podem ser inovadoras em relação às exposições de outros objetos, já que a roupa vincula-se a movimento, toque, corpo e usabilidade que induz experiências e conexões, sentimentos e identidades em uma relação de metamorfose. - A noção de que o potencial de ensino e difusão de uma cultura de design, com destaque aos contextos de Portugal e Brasil, é um campo relevante à visibilidade pública da indústria da moda nestes países e alavanca para um melhor posicionamento na competitividade global. Pelas propostas específicas e pelo contributo de fornecer informações inéditas a respeito do universo investigado, este estudo abre novas perspectivas para futuras investigações, principalmente nas áreas de museologia, museografia, história e teoria da moda e do design, design de exposição, design de produto, estudos da cultura material, comunicação e antropologia do design.