Verificaçao de soluçoes numéricas de escoamentos laminares obtidas com o método dos volumes finitos e malhas nao-estruturadas

Orientador: Carlos H.MarchiCo-orientador: Fábio A.SchneiderInclui apendiceDissertaçao (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduaçao em Engenharia Mecânica. Defesa: Curitiba, 2004Inclui bibliografiaResumo: O presente trabalho versa sobre o uso dos estimadores de erro Extrapolação de Richardson e Grid Convergence Index - GCI, baseados tanto na ordem aparente quanto na ordem assintótica, na solução das equações de Navier-Stokes aplicadas a escoamentos laminares com solução analítica conhecida. Para tal se usa um software comercial que utiliza o Método dos Volumes Finitos baseados em Elementos com malhas não-estruturadas, o CFX. Todas as malhas usadas para a solução dos problemas apresentados são tetraédricas. Os problemas escolhidos para o estudo foram: escoamento recirculante na cavidade quadrada e o escoamento completamente desenvolvido entre duas placas planas paralelas. Esta escolha se deve ao fato de se querer testar o comportamento das soluções com o refino de malha, bem como as previsões de incerteza com os erros numéricos das soluções, avaliando a efetividade destas. Outro objetivo do estudo é o de se verificar o comportamento dos estimadores de erro para uma mesma variável em diferentes pontos de uma malha bidimensional, bem como quando esta é obtida a partir de diferentes variáveis de base. Os resultados para o problema da cavidade quadrada se comportaram como o esperado com sobre-estimativas bastante significativas. Para o outro problema, os resultados mostraram uma elevada sensibilidade da ordem aparente às variações nas soluções obtidas. No problema do escoamento entre placas planas verificou-se a total dependência das estimativas de erro para diferentes pontos da malha assim como que diferentes variáveis de base levam a diferentes estimativas de erro, bem como diferentes comportamentos destas estimativas com o refino de malha. Palavras-chave: Incerteza numérica; Mecânica dos Fluidos Computacional.Abstract: The present work is about the use of the Richardson's Extrapolation and the Grid Convergence Index - GCI error estimators, based on both apparent and asymptotic orders, on the solution of the Navier-Stokes equations applied to laminar flows with known analytical solutions. For this purpose, commercial software that uses the Element-based Finite Volume Method, with unstructured meshes called CFX was used. All grids used for the solution of the proposed problems were formed with tetrahedrons. The chosen problems for this study were: recirculating flow on a square cavity and the completely developed flow between two flat plates. This choice was made because we aimed to test the behavior of the solutions with the mesh refinement as well the numerical uncertainty with the numerical errors of the obtained solutions, evaluating its effectiveness. Another target of this work was to verify the error estimator's behavior for the same variable at different points on a two-dimensional mesh, as well as when this variable is obtained from different base-variables. The results for the first problem behave as expected with significant over estimation, especially for the GCI error estimator. For the other problem, the results showed a high sensitivity of the apparent order to the variations of the obtained solutions. On the flow between two flat plates problem we verified a dependency of the error estimate with the geometric point where the solution was evaluated. Results obtained with different base-variables showed different error estimative and behavior of those with mesh refinement. Keywords: Numerical uncertainty; Computational Fluid Dynamics

Coxsackievirus A6 strains causing an outbreak of hand-foot-and-mouth disease in Northeastern Brazil in 2018

Hand-foot-and-mouth disease (HFMD) is a highly contagious viral disease commonly associated to Enteroviruses (EV). During 2018, Brazil faced massive HFMD outbreaks spread across the country. This study aimed to characterize the EV responsible for the HFMD outbreak that occurred in Paraiba State, Brazilian Northeastern region, in 2018, followed by a phylogenetic analysis to detail information on its genetic diversity. A total of 49 serum samples (one from each patient) collected from children ≤ 15 years old, clinically diagnosed with HFMD were tested for EV using conventional RT-PCR and RT-qPCR. EV infection was confirmed in 71.4% (35/49) of samples. The mean and median ages were 1.83 years and one year old, respectively. Twenty-two EV-positive samples were successfully sequenced and classified as EV-A species; 13 samples were also identified with the CV-A6 genotype. The phylogenetic analysis (VP1 region) of three samples revealed that the detected CV-A6 strains belonged to sub-lineage D3. The CV-A6 strains detected here clustered with strains from South America, Europe and West Asia strains that were also involved in HFMD cases during the 2017-2018 seasons, in addition to the previously detected Brazilian CV-A6 strains from 2012 to 2017, suggesting a global co-circulation of a set of different CV-A6 strains introduced in the country at different times. The growing circulation of the emerging CV-A6 associated with HFMD, together with the detection of more severe cases worldwide, suggests the need for a more intense surveillance system of HFMD in Brazil. In addition, this investigation was performed exclusively on serum samples, and the analysis of whole blood samples should be considered and could have shown advantages when employed in the diagnosis of enteroviral HFMD outbreaks

In vitro and in vivo antimalarial activity and cytotoxicity of extracts, fractions and a substance isolated from the amazonian plant tachia grandiflora (Gentianaceae)

Tachia sp. are used as antimalarials in the Amazon Region and in vivo antimalarial activity of a Tachia sp. has been previously reported. Tachia grandiflora Maguire and Weaver is an Amazonian antimalarial plant and herein its cytotoxicity and antimalarial activity were investigated. Spectral analysis of the tetraoxygenated xanthone decussatin and the iridoid aglyone amplexine isolated, respectively, from the chloroform fractions of root methanol and leaf ethanol extracts was performed. In vitro inhibition of the growth of Plasmodium falciparum Welch was evaluated using optical microscopy on blood smears. Crude extracts of leaves and roots were inactive in vitro. However, chloroform fractions of the root and leaf extracts [half-maximal inhibitory concentration (IC50) = 10.5 and 35.8 μg/mL, respectively] and amplexine (IC50 = 7.1 μg/mL) were active in vitro. Extracts and fractions were not toxic to type MRC-5 human fibroblasts (IC50 > 50 μg/mL). Water extracts of the roots of T. grandiflora administered by mouth were the most active extracts in the Peters 4-day suppression test in Plasmodium berghei-infected mice. At 500 mg/kg/day, these extracts exhibited 45-59% inhibition five to seven days after infection. T. grandiflora infusions, fractions and isolated substance have potential as antimalarials

In vitro and in vivo antimalarial activity and cytotoxicity of extracts, fractions and a substance isolated from the Amazonian plant Tachia grandiflora (Gentianaceae)

Tachia sp. are used as antimalarials in the Amazon Region and in vivo antimalarial activity of a Tachia sp. has been previously reported. Tachia grandiflora Maguire and Weaver is an Amazonian antimalarial plant and herein its cytotoxicity and antimalarial activity were investigated. Spectral analysis of the tetraoxygenated xanthone decussatin and the iridoid aglyone amplexine isolated, respectively, from the chloroform fractions of root methanol and leaf ethanol extracts was performed. In vitro inhibition of the growth of Plasmodium falciparum Welch was evaluated using optical microscopy on blood smears. Crude extracts of leaves and roots were inactive in vitro. However, chloroform fractions of the root and leaf extracts [half-maximal inhibitory concentration (IC50) = 10.5 and 35.8 µg/mL, respectively] and amplexine (IC50= 7.1 µg/mL) were active in vitro. Extracts and fractions were not toxic to type MRC-5 human fibroblasts (IC50> 50 µg/mL). Water extracts of the roots of T. grandiflora administered by mouth were the most active extracts in the Peters 4-day suppression test in Plasmodium berghei-infected mice. At 500 mg/kg/day, these extracts exhibited 45-59% inhibition five to seven days after infection. T. grandiflora infusions, fractions and isolated substance have potential as antimalarials

Correction: Inhibitory Effects of Hydroethanolic Leaf Extracts of Kalanchoe brasiliensis and Kalanchoe pinnata (Crassulaceae) against Local Effects Induced by Bothrops jararaca Snake Venom.

[This corrects the article DOI: 10.1371/journal.pone.0168658.]

Genomic constellation of human Rotavirus A strains identified in Northern Brazil: a 6-year follow-up (2010-2016)

Surveillance of Rotavirus A (RVA) throughout the national territory is important to establish a more complete epidemiological-molecular scenario of this virus circulation in Brazil. The aim of the present study was to investigate the genetic diversity of RVA strains circulating in Tocantins State (Northern Brazil) during six years of post-vaccination followup (2010-2016). A total of 248 stool samples were screened by next generation sequencing and 107 (43.1%) nearly full length RVA genome sequences were obtained; one sample was co-infected with two RVA strains (G2/G8P[4]). Six G and P genotypes combinations were detected: G12P[8] strains (78.6%), as well as the G3P[8] (9.3%) and G1P[8] (0.9%) were associated with a Wa-like genogroup backbone. All G2P[4] (5.6%) and G8P[4] (2.8%) strains, including the mixed G2/G8P[4] infection (0.9%) showed the DS-1-like genetic background. The two G12P[4] strains (1.9%) were associated with distinct genetic backbones: Wa-like and DS-1-like. The phylogenetic analysis revealed the circulation of lineages G1-I, G2-IV, G3-III, G8-I and G12-III, and P[4]-V and P[8]-III of the VP7 and VP4 genes, respectively. Conserved clustering pattern and low genetic diversity were observed regarding VP1-VP3 and VP6, as well as NSP1-5 segments. We identified the same RVA circulation pattern reported in other Brazilian regions in the period of 2010-2016, suggesting that rural and low-income areas may not have a different RVA genotypic distribution compared to other parts of the country. The unique presentation of whole-genome data of RVA strains detected in the Tocantins State provides a baseline for monitoring variations in the genetic composition of RVA in this area

High Heterogeneity of Echoviruses in Brazilian Children with Acute Gastroenteritis

Echoviruses (E) are a diverse group of viruses responsible for various pathological conditions in humans including aseptic meningitis, myocarditis, and acute flaccid paralysis. The detection and identification of echovirus genotypes in clinical samples is challenging due to its high genetic diversity. Here, we report the complete genome sequences of nine echoviruses, obtained by next-generation sequencing of 238 fecal samples from individuals with gastroenteritis in regions of Brazil. Detected viruses were classified into six genotypes: Three E1 sequences (BRA/TO-028, BRA/TO-069 and BRA/TO-236), one E3 (BRA/TO-018), one E11 (BRA/TO-086), one E20 (BRA/TO-016), two E29 (BRA/TO-030 and BRA/TO-193), and one E30 sequence (BRA/TO-032). Phylogenetic analysis indicated that the echoviruses E1 and E29 circulating in Brazil are divergent from strains circulating worldwide. The genotype diversity identified in our study may under-represent the total echovirus diversity in Brazil because of the small sample size and the restricted geographical distribution covered by the survey

New Variants of Squash Mosaic Viruses Detected in Human Fecal Samples

Squash mosaic virus (SqMV) is a phytovirus that infects great diversity of plants worldwide. In Brazil, the SqMV has been identified in the states of Ceará, Maranhão, Piauí, Rio Grande do Norte, and Tocantins. The presence of non-pathogenic viruses in animals, such as phytoviruses, may not be completely risk-free. Similarities in gene repertories between these viruses and viruses that affect animal species have been reported. The present study describes the fully sequenced genomes of SqMV found in human feces, collected in Tocantins, and analyzes the viral profile by metagenomics in the context of diarrhea symptomatology. The complete SqMV genome was obtained in 39 of 253 analyzed samples (15.5%); 97.4% of them belonged to children under 5 years old. There was no evidence that the observed symptoms were related to the presence of SqMV. Of the different virus species detected in these fecal samples, at least 4 (rotavirus, sapovirus, norovirus, parechovirus) are widely known to cause gastrointestinal symptoms. The presence of SqMV nucleic acid in fecal samples is likely due to recent dietary consumption and it is not evidence of viral replication in the human intestinal cells. Identifying the presence of SqMV in human feces and characterization of its genome is a relevant precursor to determining whether and how plant viruses interact with host cells or microorganisms in the human gastrointestinal tract