Browsing by Author "Costa, J."
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- Characterization of histopathological lesions in a biological model for environmental studies: Eisenia andrei Bouché. Preliminar resultsPublication . Vala, Helena; Rodriguez-Seijo, A.; Lourenço, J.; Francisco, A.; Rocha-Santos, T.; Costa, J.; Pereira, R.Introduction The strong expansion of the world production of plastics caused a severe accumulation of plastic debris in the environment, which makes them one of the most important contaminants, growing as a global environmental problem. Although the production in Europe has been relatively constant in the last 10 years, world plastic production continues to increase, affecting soil biota and their functions. Objectives Thus, in order to evaluate the effects of MP in soil-dwelling organisms, earthworms (Eisenia andrei Bouché), were exposed to standard artificial soil mixed with MPs and the authors documented, using microscopic figures, the pathological lesions found in this biological model. Material and Methods Eight adult earthworms extracted from soils contaminated with different concentrations of MP (mg/kgdw) with sizes ranging between 250-1000 m, were fixed in 10% neutral-buffered formalin and processed for routine histopathological diagnosis. Results and discussion Contrary to what would be expected, MP were not found throughout the GI tube of earthworms but several lesions were found in the individuals extracted from the soils with high MP concentrations, when compared with control group, namely epithelial intestinal atrophy and evidences of inflammatory responses to this stress agent. Conclusion Earthworms have probably avoided the consumption of the biggest MPs. However, evidences point for lesions that were likely caused by the smallest MPs that were likely egested during the depuration phase.
- Histopathological and molecular effects of microplastics in Eisenia andrei BouchéPublication . Rodriguez-Seijo, A.; Lourenço, J.; Rocha-Santos, T.A.P.; Costa, J.; Duarte, A.C.; Vala, Helena; Pereira, R.The ocean has been assumed as the main sink of microplastics (MPs), however, soils may also receive MPs from different sources and through different pathways, which may affect the biota and their role in soil functions. To the best of our knowledge, only one study, until now, reported the effects of MPs on the survival and fitness of soil organisms (Lumbricus terrestris). In our study, epigeic earthworms, of the species E. andrei, were exposed to different concentrations of MPs (0, 62.5, 125, 250, 500 and 1000 mg/kg soildw) in an OECD artificial soil and tested for reproduction, survival and growth of adults, following a standard protocol. The size of the polyethylene MPs to which earthworms were exposed ranged between 250 and 1000 μm. No significant effects were recorded on survival, number of juveniles and, in the final weight of adult earthworms after 28d of exposure, to the different concentrations of MPs. Nevertheless, FTIR-ATR of earthworms and histopathological analysis of the gut provided evidences of damages and immune system responses to MPs.
- Routine histological technique applied to a biological model for environmental studiesPublication . Vala, Helena; Rodriguez-Seijo, A.; Lourenço, J.; Garcia, C.; Francisco, A.; Rocha-Santos, T.; Costa, J.; Pereira, R.Introduction and aim Earthworms are an important test organisms used in several standard ecotoxicological tests (e.g. ISO, 2008, 2012; OECD, 2004, 1094) and they are also model organisms to test soil structure and permeability, as well as for important soil services as the degradation organic matter. Although histopathological changes have been demonstrated to be good biomarkers to assess the exposure of these animals to different physical and chemical stress agents, studies with clear and high quality images describing normal tissue conditions are scarce in the literature, so the aim of this work was to better characterize this biological model. Material and Methods Eight adult earthworms exposed to an artificial standard soil (OECD, 2004) for 28 days, were extracted and placed in a plastic box to depurate their gut content, fixed in 10% neutral-buffered formalin and processed for routine histopathological diagnosis. Results and discussion Satisfactory histological sections were obtained. Some difficulties were faced related with microtome sectioning, resulting in artefacts, namely lines across sections produced by a nick in the cutting edge of the microtome knife cutting tear, motivated by the presence of sand and other solid particles that persisted in the gut of earthworms. Nevertheless, it was possible to obtain representative figures from different earthworm sections. Conclusion Routine histological technique was effective for obtaining satisfactory histological sections and the knowledge of the histology of earthworms could be very useful for future application in environmental studies, using this biological model.
- A Study on the Sealing Efficiency of Air Curtains: 2D and 3D ApproachesPublication . Goncalves, J. C.; Costa, J.; Figueiredo, R.; Lopes, A.In industrial refrigerated spaces, such as retail stores, where sometimes doors must be open for long periods, the infiltration loads can represent more than half of the total refrigeration load. The use of air curtains can significantly reduce the air infiltration through doorways and, at the same time, it allows the free access by persons and equipment [1]. Besides the experimental research, computational fluid dynamics (CFD) has been commonly used, either adopting a two dimensional (2D) approach [1] or, more recently, through a three-dimensional (3D) perspective [2,3]. This work presents a numerical and experimental study on the performance of air curtain devices in the aerodynamic sealing of access doors of refrigerated spaces. For this propose, a 3D numerical model was developed aiming at the simulation of the turbulent non-isothermal airflow generated by the air curtain since the moment the door is opened. The calculation domain represents a laboratory scale model consisting of two similar adjacent rooms connected by a doorway over which the air curtain device is installed. One of these rooms represents a refrigerated chamber and the other, the outdoor environment. The numerical study was carried out using a commercial CFD code (ANSYS-CFX) and the turbulence effects were approached by k-_SST turbulent model. In the experimental study, the tracer gas technique was used to estimate the air exchange rate through the doorway in the initial period of the transient process and consequently assess the sealing effect obtained with the air curtain device operating at different jet velocities. The numerical results show that the air curtain simulated is appropriate to protect the doorway in its whole width, and a good agreement is verified with the experimental measurements. Results of a simplified 2D approach are also shown and compared with the 3D simulation