Oil pollution harms terrestrial ecosystems. There is an urgent requirement to improve on existing methods for detecting, mapping and establishing the precise extent of oil-impacted and oil-free vegetation. This is needed to quantify existing spill extents, formulate effective remediation strategies and to enable effective pipeline monitoring strategies to identify leakages at an early stage.
View Article and Find Full Text PDFTerrestrial oil pollution is one of the major causes of ecological damage within the Niger Delta region of Nigeria and has caused a considerable loss of mangroves and arable croplands since the discovery of crude oil in 1956. The exact extent of landcover loss due to oil pollution remains uncertain due to the variability in factors such as volume and size of the oil spills, the age of oil, and its effects on the different vegetation types. Here, the feasibility of identifying oil-impacted land in the Niger Delta region of Nigeria with a machine learning random forest classifier using Landsat 8 (OLI spectral bands) and Vegetation Health Indices is explored.
View Article and Find Full Text PDFA new preparation of δ-lactams is reported. In the presence of a Lewis acid promoter, alkoxyisocoumarins engage a range of N-aryl and N-alkyl imines to form δ-lactams with a pendent carboalkoxy substituent. A sulfonamide-thiourea catalyst enables the synthesis of these products in moderate to good enantioselectivities.
View Article and Find Full Text PDFAn amide-thiourea compound, operating through a novel ion pairing mechanism, is an efficient organocatalyst for the asymmetric reaction of homophthalic anhydride with imines. N-aryl and N-alkyl imines readily undergo formal [4+2] cycloaddition to provide lactams with high levels of enantio- and diastereoselectivity. The nature of the key chiral ion pair intermediate was elucidated by DFT calculations.
View Article and Find Full Text PDFRemote ischemic conditioning (RIC) using transient limb ischemia/reperfusion has been reported to reduce perioperative myocardial injury in patients undergoing coronary artery bypass grafting and/or valve surgery. The role of intravenous glyceryl trinitrate (GTN) therapy administered during cardiac surgery as a cardioprotective agent and whether it interferes with RIC cardioprotection is not clear and is investigated in the ERIC-GTN trial ( http://www.clinicaltrials.
View Article and Find Full Text PDFSecondary amines react with thiosalicylaldehydes in the presence of catalytic amounts of acetic acid to generate ring-fused N,S-acetals in redox-neutral fashion. A broad range of amines undergo α-sulfenylation, including challenging substrates such morpholine, thiomorpholine, and piperazines. Computational studies employing density functional theory indicate that acetic acid reduces the energy barriers of two separate steps, both of which involve proton transfer.
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