Modelação matemática da camada de plasma em microcanais

Neste estudo apresenta-se uma proposta de modelação matemática da camada de plasma observada em escoamentos sanguíneos. Numa fase inicial, a resolução do problema fez uso da otimização não linear para encontrar o modelo matemático que minimiza o erro quadrático não linear entre o modelo e os dados numéricos que caracterizam a camada de plasma. Para tal, foram testados os algoritmos Simulated Annealing, Pattern Search, Algoritmo Genético e Quasi-Newton. Neste estudo conclui-se que o método de otimização que obteve melhores resultados foi o Algoritmo Genético. Também foi possível concluir que o melhor modelo para aproximar os dados numéricos que caracterizam a camada de plasma presente em escoamentos sanguíneos é baseado na soma de funções trigonométricas.Os autores agradecem à FCT, COMPETE, QREN e União Europeia (FEDER) no âmbito dos projetos PTDC/SAU-ENB/116929/2010 e EXPL/EMS-SIS/2215/2013.info:eu-repo/semantics/publishedVersio

Método semi-automático em MatLab para calcular o coeficiente de dispersão de eritrócitos em microcanais

O sangue é um fluido fisiológico de elevada importância para o normal funcionamento do organismo humano pois desempenha funções essenciais à vida. Um ser humano possui cerca de 5 litros de volume sanguíneo no organismo onde, aproximadamente, metade desse volume é composto por eritrócitos e estes influenciam fortemente as propriedades do escoamento sanguíneo. A microcirculação tem uma função muito importante na circulação sanguínea pois é nesta que ocorre a maioria das trocas de substâncias entre o sangue e os tecidos vizinhos. O estudo do comportamento dos eritrócitos apresenta uma elevada importância na avaliação precoce de alterações comportamentais dos mesmos evitando o aparecimento e a evolução de patologias no organismo. Neste estudo, com o auxílio do MatLab, foi desenvolvido um método semi-automático para o cálculo do Coeficiente de dispersão de eritrócitos em microcanais. O algoritmo desenvolvido em MatLab foi validado através da comparação com um método manual e foi testado em vários elementos selecionados e seguidos em segmentos de imagens, obtidos por um sistema de micoscopia confocal (Leble et al., 2011, Lima et al., 2006, 2008). Os resultados obtidos foram bastante satisfatórios. A validação do método automático foi positiva, apresentando um erro despresável em comparação com o método manual. Os resultados obtidos no cálculo do coeficiente de dispersão através do método semi-automático aproximaram-se dos valores teóricos esperados

Red blood cells motion in a glass microchannel

The motion of the red blood cells (RBCs) flowing in microvessels and microchannels depend on several effects, such as hematocrit (Hct), geometry, and temperature. According to our knowledge, the effect of the temperature on RBC motion was never investigated at a microscale level. Hence, the aim of the present work is to determine the effect of the temperature on the RBC’s trajectories and to investigate the best approximation of the trajectories through a nonlinear optimization. In vitro human blood was pumped through a 100 mm circular microchannel and by using a confocal micro- PTV system the RBC’s trajectories were measured at different temperatures, i.e., 25◦C and 37◦C. In this study we measured the motion of forty cells flowing in the middle of the microchannel and applied different functions to approximate its behavior.This study was supported in part by the following grants: Grant-in-Aid for Science and Technology (PTDC/SAU-BEB/108728/2008, PTDC/SAU-BEB/105650/2008 and PTDC/EME-MFE/099109/2008) from the Science and Technology Foundation (FCT) and COMPETE, Portugal

Motion of red blood cells in a glass microchannel: a global optimization approach

Este artigo também deve ser anexado ao Departamento Tecnologia Mecânica, docente Rui Alberto Madeira Macedo Lima.In this work we characterized the behavior of red blood cell motion through a glass microchannel. In this study we consider the radial displacement of forty red blood cells and use different functions to approximate the radial displacement of each of them, by means of global optimization using stretched simulated annealing method. Some numerical results are shown

Ciprofloxacin removal catalysed by conductive carbon materials

Current wastewater treatment technologies are not effective in the removal of pharmaceuticals. In anaerobic bioreactors, the electrons produced during the oxidation of organic matter can potentially be used for the biological reduction of pharmaceuticals. However, these reactions occur generally at a slow rate, due to electron transfer limitations, and might be accelerated through redox mediators (RM). Carbon nanomaterials (CM) have been effective RM in the biological reduction of other pollutants. For instance, CNT@2%Fe were found to increase 76-fold the biological reduction of Acid Orange 10. The magnetic properties of those composites allow their easier recover after the process by using a magnetic field. In this study, CNT and CNT@2%Fe were studied in the anaerobic removal of Ciprofloxacin (CIP). Furthermore, the potential contribution of adsorption and biodegradation processes for CIP removal was assessed. Toxicity assessment is highly important as it is desired that the products formed after the process are not more toxic than the initial compound. Moreover, the evaluation of the possible contribution of nanomaterials used in the process for the final toxic effect of threated solution, is crucial. In this sense, the detoxification of the treated solutions was evaluated towards Vibrio fischeri.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2019 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

Unveiling the early events of Pseudomonas aeruginosa adaptation in cystic fibrosis airway environment using a long-term in vitro maintenance

Pseudomonas aeruginosa chronic infections are the major cause of high morbidity and mortality in cystic fibrosis (CF) patients due to the use of sophisticated mechanisms of adaptation, including clonal diversification into specialized CF-adapted phenotypes. In contrast to chronic infections, very little is known about what occurs after CF lungs colonization and at early infection stages. This study aims to investigate the early events of P. aeruginosa adaptation to CF environment, in particular, to inspect the occurrence of clonal diversification at early stages of infection development and its impact on antibiotherapy effectiveness. To mimic CF early infections, three P. aeruginosa strains were long-term grown in artificial sputum (ASM) over 10 days and phenotypic diversity verified through colony morphology characterization. Biofilm sub- and inhibitory concentrations of ciprofloxacin were applied to non- and diversified populations to evaluate antibiotic effectiveness on P. aeruginosa eradication. Our results demonstrated that clonal diversification might occur after ASM colonization and growth. However, this phenotypic diversification did not compromise ciprofloxacin efficacy in P. aeruginosa eradication since a biofilm minimal inhibitory dosage would be applied. The expected absence of mutators in P. aeruginosa populations led us to speculate that clonal diversification in the absence of ciprofloxacin treatments could to be driven by niche specialization. Yet, biofilm sub-inhibitory concentrations of ciprofloxacin seemed to overlap niche specialization as fitter variants had emerged, such as mucoid, small colony and pinpoint variants, known to be highly resistant to antibiotics. The pathogenic potential of all emergent colony morphotypes-associated bacteria, distinct from the wild-morphotypes, revealed that P. aeruginosa evolves to a non-swimming phenotype. Impaired swimming motility seemed to be one of the first evolutionary steps of P. aeruginosa in CF lungs that could pave the way for further adaptation steps including biofilm formation and progress to chronic infection. Based on our findings, impaired swimming motility seemed to be a candidate to disease marker of P. aeruginosa infection development. Despite our in vitro CF model represents a step forward towards in vivo scenario and it provided valuable insights about the early events, more and distinct P. aeruginosa strains should be studied to strengthen our results.This work was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/ BIO/04469 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. The authors also acknowledge COMPETE2020 and FCT for the project POCI-01-0145FEDER-029841.info:eu-repo/semantics/publishedVersio

Analysis of the cell-free layer in a circular microchannels: trajectories of labeled red bllod cells

In this experimental work, we measure the trajectories of the cell-free layer (CFL) by tracking labeled red blood cells (RBCs) flowing around the boundary of the RBCs core. The circular glass microchannels studied are 100 um in diameter. The images are captured using confocal system and are post-processed using Image J and MATLAB. The results suggest that the trajectories follows a polynomial function

Cell-free layer (CFL) analysis in a glass capillary: comparison between a manual and automatic method

In this study, in vitro blood flowing through a 100 m glass capillary was studied. The images were captured using a confocal system and post-processed using Image J and MatLab. The aim of the present work, was to measure the trajectories of the cell-free layer (CFL) by using two different methods, i. e., a manual method (MM) and an automatic method (AM). For theMM we have used amanual tracking plugin (MTrackJ) from Image J to track labeled red blood cells (RBCs) flowing around the boundary of the RBCs core. For the AM we have used a MatLab scripts to measure automatically the CFL trajectories. The preliminary numerical results suggest that the CFL trajectories follow a polynomial function for both methods.The authors acknowledge the financial support provided by: PTDC/SAU-BEB/108728/2008, PTDC/SAU-BEB/105650/2008, PTDC/EME-MFE/099109/2008 and PTDC/SAU-ENB/116929/2010 from the FCT (Science and Technology Foundation) and COMPETE, Portugal

Cell-free layer measurements in bifurcating microchannels: a global approach

In the present work, in vitro blood flowing through bifurcating microchannels was studied, with the aim of characterizing the cell-free layer (CFL). The original images were obtained by means of a high-speed video microscopy system and then processed in MatLab using the Image Processing Toolbox. The numerical data was obtained automatically and analyzed by optimization techniques using the genetic algorithm approach. The results suggest that the CFL were formed in a similar way at the upper and lower regions in all bifurcations, and the measurements can be approximated through a sum of trigonometric functions