Efeito antimicrobiano de extrato aquoso rico em polifenóis de casca de jabuticaba em Staphylococcus aureus e Escherichia coli

Jaboticaba peels are an important source of health-benefit and antimicrobial compounds. The present work aims to evaluate concentration of polyphenolics and the mode of action of aqueous extract from jaboticaba peels against Staphylococcus aureus and Escherichia coli. Jaboticaba peel extract showed minimum inhibitory concentration and minimum bactericidal concentration against S. aureus of 5.1 g L-1 and 10.1 g L-1, respectively; meanwhile, against E. coli the parameters were 2.0 g L-1 and 3.4 g L-1. Kinetics of viable cell counts indicated a bacteriolytic action against both bacteria and Scanning Electron Microscopy (SEM) showed that jaboticaba peel extract causes subtle morphological changes in bacterial cells. Concentration of total polyphenols in the extract was 1535.04±36.05 mg of gallic acid equivalent (GAE) mL-1, monomeric anthocyanins was 14.52 ± 0.98 mg of cyanidin 3-glucoside mL-1, condensed tannins was 0.49 ± 0.05 mg of epicatechin equivalent mL-1 and phenolic acids was 80.04 ± 4.11 mg of caffeic acid equivalent (CAE) mL-1, which have demonstrated well-documented antibacterial activity. In conclusion, jaboticaba peel aqueous extract may be an interesting natural preservative to control Gram-positive and Gram-negative bacteria growth when interacting with the bacteria cell wall.As cascas de jabuticaba são uma importante fonte de benefícios à saúde e compostos com atividade antimicrobiana. O presente trabalho tem como objetivo avaliar a concentração de polifenóis e o modo de ação do extrato aquoso da casca da jabuticaba contra Staphylococcus aureus e Escherichia coli. O extrato da casca da jabuticaba apresentou concentração inibitória mínima e concentração bactericida mínima contra S. aureus de 5,1 g L-1 e 10,1 g L-1, respectivamente; já contra E. coli, esses parâmetros foram 2,0 g L-1 e 3,4 g L-1. A cinética da contagem de células viáveis indica uma ação bacteriolítica contra ambas as bactérias e a microscopia eletrônica de varredura mostrou que o extrato da casca da jabuticaba causa sutis alterações morfológicas nas células bacterianas. A concentração de polifenóis totais no extrato foi 1.535,04±36,05 mg ácido gálico equivalente mL-1; antocianinas monoméricas, 14,52±0,98 mg cianidina 3-glicosídeo mL-1; taninos condensados, 0,49 ± 0,05 mg equivalente epicatequina mL-1, e ácidos fenólicos, 80,04±4,11 mg ácido cafeico equivalente mL-1, compostos que já demonstraram atividade antibacteriana bem documentada. Em conclusão, o extrato aquoso da casca de jabuticaba mostra-se um bioconservante interessante para o controle de bactérias Gram-positivas e Gram-negativas, e interage com a parede celular bacteriana

Analytically divergence-free discretization methods for Darcy's problem

Radial basis functions are well known for their applications in scattered data approximation and interpolation. They can also be applied in collocation methods to solve partial differential equations. We develop and analyse a mesh-free discretization method for Darcy's problem. Our approximation scheme is based upon optimal recovery, which leads to a collocation scheme using divergence-free positive denite kernels. Besides producing analytically incompressible flow fields, our method can be of arbitrary order, works in arbitrary space dimension and for arbitrary geometries. Firstly we establish Darcy's problem. To introduce the scheme we review and study divergence-free and curl-free matrix-valued kernels and their reproducing kernel Hilbert spaces. After developing the scheme, we find the approximation error for smooth target functions and the optimal approximation orders. Furthermore, we develop Sobolev-type error estimates for target functions rougher than the approximating function and show that the approximation properties extend to those functions. To find these error estimates, we apply band-limited approximation. Finally, we illustrate the method with numerical examples

Beyond Books: Evaluating Maker Spaces in Ontario’s Municipal Library Systems

This exploratory research paper looks at how Ontario’s municipal library systems evaluate their maker spaces and programming. The literature review provides context on the purpose and value of libraries, the structure and agency of municipal libraries in Ontario and academic and applied studies of program evaluation. The research seeks to answer four questions: What municipal libraries have maker spaces and what are their characteristics? How have they positioned this service in terms of purpose and value? How have they measured success? What can Ontario’s municipal library systems learn from the evaluation of maker spaces to position themselves for the future? An analysis of 2018 statistical data from the Ministry of Ministry of Heritage, Sport, Tourism and Culture Industries in Ontario as well as primary documents from municipal library systems that responded to the research request are used to answer these questions. Ultimately, although outcome based frameworks were found in the literature review, this research finds that few municipal library systems in Ontario consider evaluation of maker spaces beyond participant counts and other inputs. Two examples from Toronto Public Library and Vaughan Public Library were the exceptions in providing promising outcome based frameworks. It is important for municipal library systems to continue to demonstrate their value to their municipal funders through outcome base evaluation, which will ensure they can continue to deliver on the purpose and value of libraries to the communities they serve

Topological recursion for Masur-Veech volumes

We study the Masur-Veech volumes $MV_{g,n}$ of the principal stratum of the moduli space of quadratic differentials of unit area on curves of genus $g$ with $n$ punctures. We show that the volumes $MV_{g,n}$ are the constant terms of a family of polynomials in $n$ variables governed by the topological recursion/Virasoro constraints. This is equivalent to a formula giving these polynomials as a sum over stable graphs, and retrieves a result of \cite{Delecroix} proved by combinatorial arguments. Our method is different: it relies on the geometric recursion and its application to statistics of hyperbolic lengths of multicurves developed in \cite{GRpaper}. We also obtain an expression of the area Siegel--Veech constants in terms of hyperbolic geometry. The topological recursion allows numerical computations of Masur--Veech volumes, and thus of area Siegel--Veech constants, for low $g$ and $n$, which leads us to propose conjectural formulas for low $g$ but all $n$. We also relate our polynomials to the asymptotic counting of square-tiled surfaces with large boundaries.Comment: 75 pages, v2: added a section on enumeration of square-tiled surface

Unveiling fungal community structure along different levels of anthropic disturbance in a South American subtropical lagoon

Studies of fungal communities through amplicon metagenomics in aquatic environments, particularly in freshwater ecosystems, are still relatively recent. Unfortunately, many of these water bodies are facing growing threats from human expansion, such as effluent discharge from various human activities. As a result, these effluents have the potential to significantly alter the characteristics of water bodies and, subsequently, impact the diversity of their resident microorganisms. In this context, our objective was to investigate whether the fungal community structure varies according to the presence of different anthropic disturbances. We expect (i) the diversity of fungi will be greater and (ii) more specific unique operational taxonomic units (OTUs) related to each ecotonal system will be found compared to other sites of a lagoon. The study was conducted in the Tramandaí Lagoon (subtropical southern Brazil) at four distinct sampling points (estuary, middle of the lagoon, crop field area, and near a residential area where the Tramandaí River flows into the lagoon). As expected, the estuary and residential zones, which are ecotones, exhibited greater fungal diversity and more specific OTUs compared to the middle of the lagoon and crop field area. Moreover, a substantial proportion of fungal taxa could not be identified at the genus level, with many only classified at the phylum level, indicating potential new lineages. These findings underscore our limited understanding of the subtropical freshwater mycobiota