Search Results - "Costa, João P."

Publication Catalog - "Costa, João P."

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  1. 1

    Influence of the hip joint modeling approaches on the kinematics of human gait

    Publication
    by Costa, João P. Morais
    Other Authors: Peixoto, Joaquim Jorge Gomes; Moreira, Pedro; Souto, A. Pedro; Flores, Paulo; Lankarani, Hamid M.
    The influence of the hip joint formulation on the kinematic response of the model of human gait is investigated throughout this work. To accomplish this goal, the fundamental issues of the modeling process of a planar hip joint under the framework of multibody systems are revisited. In particular, the formulations for the ideal, dry, and lubricated revolute joints are described and utilized for the interaction of femur head inside acetabulum or the hip bone. In this process, the main kinematic and dynamic aspects of hip joints are analyzed. In a simple manner, the forces that are generated during human gait, for both dry and lubricated hip joint models, are computed in terms of the system’s state variables and subsequently introduced into the dynamics equations of motion of the multibody system as external generalized forces. Moreover, a human multibody model is considered, which incorporates the different approaches for the hip articulation, namely ideal joint, dry, and lubricated models. Finally, several computational simulations based on different approaches are performed, and the main results presented and compared to identify differences among the methodologies and procedures adopted in this work. The input conditions to the models correspond to the experimental data capture from an adult male during normal gait. In general, the obtained results in terms of positions do not differ significantly when the different hip joint models are considered. In sharp contrast, the velocity and acceleration plotted vary significantly. The effect of the hip joint modeling approach is clearly measurable and visible in terms of peaks and oscillations of the velocities and accelerations. In general, with the dry hip model, intra-joint force peaks can be observed, which can be associated with the multiple impacts between the femur head and the cup. In turn, when the lubricant is present, the system’s response tends to be smoother due to the damping effects of the synovial fluid.
    2016 article Portugal open access
  2. 2

    Trnsys simulation results of an existing monitored small scale CHCP system and mathematical model adaptations of the air-cooled ammonia chiller and CHP prototypes

    Publication
    by Mendes, J. Farinha
    Other Authors: Coelho, Ricardo; Cardoso, João P.; Costa, João P.; Fernández, David; Silva, António R. et al.
    This work is a TRNSYS simulation of solar thermal system working together with an existing small sized CHCP (Combinet Heat Cooling and Power) demonstration project, included in the workpackage 5 (simulation) of the PolySMART project. The first objective of this work is to fine tune simulation parameters of the simulation Units (or Types), based on monitoring data collected during the first semester of 2010. The second objective is to further develop the mathematical models of type 107 (Hot Water-Fired Single-Effect Absorption Chiller) and type 120 (HYDROGEMS: Diesel Engine Generator System (DEGS) - Version 1.1). This will tackle the remaining differences between the real and simulated systems. These differences are due to the fact that both the CHP and the Ammonia-Water Air Cooled Chiller are prototypes. The third objective is to simulate the performance of different thermal collectors, some of which are also prototypes, and choose a proper solution for future experiments. The forth objective is to compare local weather data sets, collected on site since 2007, with proven standard data sets. Further work may be developed regarding the fan coils used to carry in/out heat.
    2010 conference output Portugal open access
  3. 3

    Monitoring Results of a Small Scale CHCP System

    Publication
    by Mendes, J. Farinha
    Other Authors: Cardoso, João P.; Coelho, Ricardo; Costa, João P.; Fernández, David; Silva, António R. et al.
    A small scale trigeneration system for combined heat, cold and power production was developed and installed at the Laboratório Nacional de Energia e Geologia, I.P. campus in Lisbon, Portugal. This system is one of the twelve experimental trigeneration systems being developed and tested across Europe within the PolySMART project. The CHCP system main constituents are a purpose made CHP prototype with an estimated 27kW maximum heat capacity and 9,6kW maximum electrical capacity and a TDC prototype with 8kW cooling power. The hydraulic scheme is presented and briefly analyzed. The data obtained during the monitoring of the system during heat and cold seasons is presented and analyzed for the global system. Main components behavior is analyzed with regard of their real performance when installed on a CHCP system.
    2010 conference output Portugal open access
  4. 4

    Major factors influencing the quantification of Nile Red stained microplastics and improved automatic quantification (MP-VAT 2.0)

    Publication
    by Prata, Joana C.
    Other Authors: Alves, Jorge R.; da Costa, João P.; Duarte, Armando C.; Rocha-Santos, Teresa
    Automated count of Nile Red fluorescent microplastics allows fast and reliable quantification. However, factors involving staining, digital camera conditions and settings introduce variability to the results. The objective of this paper is to identify and propose solutions to these factors and improve on the previous MP-VAT script. While removal of digital sensor defects had little influence on results and staining can be reduced to 5 min, Nile Red concentrations cannot be reduced <0.01 mg mL-1, the 470 nm LED lantern emission must be >1600 lx, and photographic conditions should be maintained as stable as possible ideally improving the filter membrane area and using the recommended settings of 2 s, ISO100, F5.6. It was also found that Nile Red can be removed from microplastics using acetone or hydrogen peroxide with iron. More importantly, both particles and fluorescent are lost with time and thus quantification should be conducted within a week. Finally, MP-VAT 2.0 was developed to remove unselected areas and to identify only red particles, excluding white reflections from quantification. This updated version of MP-VAT produced improved recovery rates of 98.2 ± 6.9 for spiked samples and 95.9 ± 10.3 on actual environmental samples, presenting a cheap and reliable complementary method for microplastic identification.
    2020 article Portugal open access
  5. 5

    Anatomia quantitativa, digestibilidade in vitro e composição química de cultivares de Brachiaria brizantha

    Publication
    by Tsuzukibashi,Denise
    Other Authors: Costa,João P. R.; Moro,Fabiola V.; Ruggieri,Ana C.; Malheiros,Euclides B.
    Origin: SciELO Portugal
    Objetivou-se avaliar três cultivares de Brachiaria brizantha (Marandu, Piatã e Xaraés), em três idades de corte, quanto à composição química, digestibilidade in vitro e anatomia quantitativa. O experimento foi realizado em um delineamento inteiramente casualizado arranjado em um fatorial, sendo três cultivares, três idades de corte e dois níveis de inserção no perfilho (apical e basal). Para as variáveis relacionadas com a composição química e digestibilidade não foi utilizado o fator nível de inserção. Foram mensuradas as áreas dos tecidos seguindo a descrição usual em histologia vegetal. A cv. Xaraés apresentou maior área de epiderme e esclerênquima na lâmina foliar e maior tecido vascular lignificado+esclerênquima e bainha parenquimática do feixe vascular na bainha foliar (p<0,05). As cv. Marandu e Piatã apresentaram maior áreade parênquima na bainha foliar (p<0,05). O esclerênquima apresentou efeito linear decrescente para a lâmina foliar para todas as cultivares entre as idades de corte e efeito linear crescente para a cv. Xaraés na bainha foliar (p<0,05). A cv. Marandu apresentou maior digestibilidade verdadeira in vitro da matéria seca e proteína bruta, e menor fibra em detergente ácido (p<0,05). A cv. Marandu apresentou melhor valor nutritivo, digestibilidade e maior área de tecidos de maior digestibilidade.
    2016 article Portugal open access
  6. 6

    Anatomia quantitativa, digestibilidade in vitro e composição química de cultivares de Brachiaria brizantha

    Publication
    by Tsuzukibashi, Denise
    Other Authors: Costa, João P.R.; Moro, Fabiola V.; Ruggieri, Ana C.; Malheiros, Euclides B.
    Objetivou-se avaliar três cultivares de Brachiaria brizantha (Marandu, Piatã e Xaraés), em três idades de corte, quanto à composição química, digestibilidade in vitro e anatomia quantitativa. O experimento foi realizado em um delineamento inteiramente casualizado arranjado em um fatorial, sendo três cultivares, três idades de corte e dois níveis de inserção no perfilho (apical e basal). Para as variáveis relacionadas com a composição química e digestibilidade não foi utilizado o fator nível de inserção. Foram mensuradas as áreas dos tecidos seguindo a descrição usual em histologia vegetal. A cv. Xaraés apresentou maior área de epiderme e esclerênquima na lâmina foliar e maior tecido vascular lignificado+esclerênquima e bainha parenquimática do feixe vascular na bainha foliar (p<0,05). As cv. Marandu e Piatã apresentaram maior áreade parênquima na bainha foliar (p<0,05). O esclerênquima apresentou efeito linear decrescente para a lâmina foliar para todas as cultivares entre as idades de corte e efeito linear crescente para a cv. Xaraés na bainha foliar (p<0,05). A cv. Marandu apresentou maior digestibilidade verdadeira in vitro da matéria seca e proteína bruta, e menor fibra em detergente ácido (p<0,05). A cv. Marandu apresentou melhor valor nutritivo, digestibilidade e maior área de tecidos de maior digestibilidade.
    2019 article Portugal open access
  7. 7

    A new approach for routine quantification of microplastics using Nile Red and automated software (MP-VAT)

    Publication
    by Prata, Joana C.
    Other Authors: Reis, Vanessa; Matos, João T. V.; da Costa, João P.; Duarte, Armando C.; Rocha-Santos, Teresa
    Microplastics are widespread contaminants in the environment. However, most identification protocols rely on long and subjective visual counting, which could be improved using staining dyes. Thus, the objective of this work is to identify the best staining dye protocol and create an objective and quick automated counting software for microplastics. Tests were conducted to identify the most appropriate of eight staining dye solutions and of six wavelengths for virgin and weathered synthetic polymers, textile fibers, natural organic matter and filters. Nile Red produced the best results (without interfering in infrared spectra) rendering microplastics fluorescent at 254 nm, but with limited number of fluorescent polymers, and at 470 nm (with orange filter), with fluorescence of plastics as well as natural organic matter (requiring a digestion step). Next, a script was developed in ImageJ for the automatic quantification and characterization in shape (fiber, fragment, particle) and size of fluorescent microplastics, the Microplastics Visual Analysis Tool (MP-VAT). MP-VAT was evaluated, producing recovery rates in the range of 89.0-111.1% in spiked filters under 470 nm. Furthermore, this package is accompanied by a script that sets a scale from a known filter diameter, MP-SCALE, and a script that allows user threshold setting, MP-ACT.
    2019 article Portugal open access
  8. 8

    A One Health perspective of the impacts of microplastics on animal, human and environmental health

    Publication
    by Prata, Joana C.
    Other Authors: da Costa, João P.; Lopes, Isabel; Andrady, Anthony L.; Duarte, Armando C.; Rocha-Santos, Teresa
    Microplastics contamination is widespread in the environment leading to the exposure of both humans and other biota. While most studies overemphasize direct toxicity of microplastics, particle concentrations, characteristics and exposure conditions being used in these assays needs to be taken into consideration. For instance, toxicity assays that use concentrations over 100,000 times higher than those expected in the environment have limited practical relevance. Thus, adverse effects on animal and human health of current environmental concentrations are identified as a knowledge gap. Conversely, this does not suggest the lack of any significant effects of microplastics on a global scale. The One Health approach provides a novel perspective focused on the intersection of different areas, namely animal, human, and environmental health. This review provides a One Health transdisciplinary approach to microplastics, addressing indirect effects beyond simple toxicological effects. Microplastics can, theoretically, change the abiotic properties of matrices (e.g., soil permeability) and interfere with essential ecosystem functions affecting ecosystem services (e.g., biogeochemical processes) that can in turn impact human health. The gathered information suggests that more research is needed to clarify direct and indirect effects of microplastics on One Health under environmentally relevant conditions, presenting detailed knowledge gaps.
    2021 article Portugal open access
  9. 9

    An easy method for processing and identification of natural and synthetic microfibers and microplastics in indoor and outdoor air

    Publication
    by Prata, Joana C.
    Other Authors: Castro, Joana L.; da Costa, João P.; Duarte, Armando C.; Cerqueira, Mário; Rocha-Santos, Teresa
    Microplastics and microfibers can contaminate every matrix, including in the atmosphere, thus leading to incidental inhalation. However, concentrations of airborne synthetic particle in indoor and outdoor environments are not well understood due to the complexities of sampling, sample processing and identification. This work aims at producing a simple protocol to determine the concentrations of airborne microplastics and fibers. This is accomplished by removing organic matter using hydrogen peroxide (H2O2), followed by removal of mineral matter by density separation with sodium iodide (NaI). Finally, identification of fibers into synthetic or natural under the stereomicroscope can be achieved following a diagram produced by systematically observing the most common textile fibers. This method produces a recovery rate of 94.4 % for spiked samples and has been proven suitable for environmental samples. •Fibers and microplastics in air are easier to identify after carbonaceous matter removal;•No loss of microfiber is expected from the solutions used;•Recovery rates of spiked samples is 94.4 %.
    2020 article Portugal open access
  10. 10

    Identifying a quick and efficient method of removing organic matter without damaging microplastic samples

    Publication
    by Prata, Joana C.
    Other Authors: da Costa, João P.; Girão, Ana V.; Lopes, Isabel; Duarte, Armando C.; Rocha-Santos, Teresa
    Natural organic matter may confound the detection of microplastics, requiring a removal step. However, most available protocols are long and lack information on removal efficiency and polymer degradation. Thus, we have determined the digestion efficiency (%) for a pool of organic matter (algae, driftwood, feathers, fish muscle, paraffin, palm oil) for five digestion solutions, hydrogen peroxide (H2O2), hydrogen peroxide with iron catalyst (H2O2 + Fe), potassium hydroxide (KOH), nitric acid (HNO3), and sodium dodecyl sulphate (SDS), under two temperatures (room temperature at 25 °C, 50 °C) and two periods (1, 6 h). H2O2 + Fe and KOH at 50 °C for 1 h had the highest digestion efficiencies, of 65.9% and 58.3% respectively (mostly limited by driftwood and paraffin). Further testing revealed that H2O2 + Fe is more appropriate for plant material and KOH for animal tissue. Weight loss (%), Fourier transform infrared spectrometry and carbonyl index of 9 virgin and 6 weathered polymers (polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polyvinyl chloride, cellulose acetate, nylon) revealed that only identification of cellulose acetate was hindered. Filters were also tested revealing that quartz and glass fibre filters are resistant to these protocols. Thus, a digestion protocol based on H2O2 + Fe or KOH at 50 °C for 1 h may be used on microplastic samples.
    2019 article Portugal open access