Caracterização morfológica de nanocristais de celulose por microscopia de força atômica

RESUMO O isolamento de nanocristais de celulose (CNCs) de fibras vegetais é uma alternativa promissora para sua aplicação como reforço em matrizes poliméricas. A caracterização dos CNCs é fundamental para a confiabilidade da técnica, além de determinar as aplicações possíveis a partir de cada tipo de fibra. A partir da técnica de microscopia de força atômica, um estudo da morfologia e distribuição dos CNCs de semente de manga, vagem de algaroba, pseudocaule da bananeira e fibra do mesocarpo de dendê foi realizado neste trabalho. Os CNCs foram obtidos via reação hidrolítica com ácido sulfúrico em concentrações que variaram de acordo com a fonte da fibra. Os resultados obtidos revelaram dimensões variando de 300 a 500 nm em comprimento e 4 a 16 nm em diâmetro. A apresentação morfológica em forma de agulha demonstrou que o isolamento das fibras de celulose em CNCs foi efetiva. A razão de aspecto associada à formação cilíndrica em agulha dos CNCs isolados evidenciou o alto potencial das fontes de dendê e de vagem de algaroba para o reforço de bionanocompósitos

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Anthropogenic disturbance in tropical forests can double biodiversity loss from deforestation

© 2016 Macmillan Publishers Limited. All rights reserved. Concerted political attention has focused on reducing deforestation, and this remains the cornerstone of most biodiversity conservation strategies. However, maintaining forest cover may not reduce anthropogenic forest disturbances, which are rarely considered in conservation programmes. These disturbances occur both within forests, including selective logging and wildfires, and at the landscape level, through edge, area and isolation effects. Until now, the combined effect of anthropogenic disturbance on the conservation value of remnant primary forests has remained unknown, making it impossible to assess the relative importance of forest disturbance and forest loss. Here we address these knowledge gaps using a large data set of plants, birds and dung beetles (1,538, 460 and 156 species, respectively) sampled in 36 catchments in the Brazilian state of Pará. Catchments retaining more than 69-80% forest cover lost more conservation value from disturbance than from forest loss. For example, a 20% loss of primary forest, the maximum level of deforestation allowed on Amazonian properties under Brazil's Forest Code, resulted in a 39-54% loss of conservation value: 96-171% more than expected without considering disturbance effects. We extrapolated the disturbance-mediated loss of conservation value throughout Pará, which covers 25% of the Brazilian Amazon. Although disturbed forests retained considerable conservation value compared with deforested areas, the toll of disturbance outside Pará's strictly protected areas is equivalent to the loss of 92,000-139,000 km2 of primary forest. Even this lowest estimate is greater than the area deforested across the entire Brazilian Amazon between 2006 and 2015 (ref. 10). Species distribution models showed that both landscape and within-forest disturbances contributed to biodiversity loss, with the greatest negative effects on species of high conservation and functional value. These results demonstrate an urgent need for policy interventions that go beyond the maintenance of forest cover to safeguard the hyper-diversity of tropical forest ecosystems