RESUMO
Studies reveal that mangroves have the ability to store underground carbon more than a tropical forest, and this function is classified as the second most important to mitigate the effects of climate change. However, part of the carbon fixed returns to the atmosphere, and this is done through soil respiration. The present study seeks to quantify the total soil efflux (a subrogate of total soil respiration) that includes both autotrophic and heterotrophic soil efflux, emitted by a Panama's mangrove swamp, as well as to investigate what drivers are important. Firstly, 3 plots were established with predominant mangroves species, such as salty mangrove tree (Avicennia bicolor Standl.) and black mangrove tree (Avicennia germinans L.). Secondly, a forest inventory was carried out in one ha, resulting in 371 trees ha-1, where the salty mangrove tree prevailed with 219 individuals in front of the black mangrove tree, with 152 trees. In addition, tree level measurements were performed such as diameter at breast height (DBH), crown diameter and distance between trees. Third, using a Licor 6400XT infrared gas analyzer system and a meteorological tower, soil CO2 fluxes and air and soil temperature were measured respectively. Results showed a total of 33.61 t of CO2 ha-1 emitted by the soil of the mangrove in 3.5 months.
RESUMO
Design of a smart drug delivery system is a topic of current interest. Under this perspective, polymer nanocomposites (PNs) of butyl acrylate (BA), methacrylic acid (MAA), and functionalized carbon nanotubes (CNTsf) were synthesized by in situ emulsion polymerization (IEP). Carbon nanotubes were synthesized by chemical vapor deposition (CVD) and purified with steam. Purified CNTs were analyzed by FE-SEM and HR-TEM. CNTsf contain acyl chloride groups attached to their surface. Purified and functionalized CNTs were studied by FT-IR and Raman spectroscopies. The synthesized nanocomposites were studied by XPS, 13C-NMR, and DSC. Anhydride groups link CNTsf to MAA-BA polymeric chains. The potentiality of the prepared nanocomposites, and of their pure polymer matrices to deliver hydrocortisone, was evaluated in vitro by UV-VIS spectroscopy. The relationship between the chemical structure of the synthesized nanocomposites, or their pure polymeric matrices, and their ability to release hydrocortisone was studied by FT-IR spectroscopy. The hydrocortisone release profile of some of the studied nanocomposites is driven by a change in the inter-associated to self-associated hydrogen bonds balance. The CNTsf used to prepare the studied nanocomposites act as hydrocortisone reservoirs.