A homologous series of biosurfactants has been synthesized by a novel sustainable biotransformation technique and compared with three other enzymatic processes. 6-O-Alkanoyl-methyl-a-D-glucopyranosides were obtained by lipase mediated esterification of methyl-a-D-glucopyranoside with capric acid C 10:0 , lauric acid C 12:0 , myristic acid C 14:0 , palmitic acid C 16:0 , and oleic acid C 18:1 . Solvent free transformations were compared with the use of ionic liquids and organic solvents. The lipase from Candida antarctica B, immobilized on macroporous acrylic acid beads (Novozyme 435), was employed either untreated or coated with small amounts of ionic liquids. This resulted in superior efficiencies (80%) with 1-butyl-4-methylpyridine hexafluorophosphate [4bmpy][PF 6 ] and broader substrate tolerance in comparison to solvent free transformation. The results show a positive correlation with increasing polarity of the ionic liquids used as liquid film-coating, which was in opposition to the use of the same ionic liquid as solvent. The analysis of the ionic liquid film coated catalyst carriers was performed by optical and scanning electron microscopy (SEM).
Artemisinin is a natural molecule highly active against malaria. At present, the extraction of this molecule from the leaves of Artemisia annua L. remains the only viable method to produce cheaply large quantities of artemisinin. Agronomic research on this plant species aims to improve agricultural yields, to decrease production costs and to ensure a steady global supply of artemisinin. These research activities require an easy, rapid, low cost, and reliable analytical technique to quantify the artemisinin content in the leaves. Thin layer chromatography (TLC) methods to quantify this molecule have already been published. However, this method does not allow the quantification of the total artemisinin content in the leaves. In order to validate the TLC method, results obtained with this method were related to results for the same samples obtained by accelerated solvent extraction and high pressure liquid chromatography with an evaporative light scattering detector (ASE-HPLC-ELSD). Using the Nernst partition law, a corrective factor of 1.21 is suggested to enable information about the true total amount of artemisinin in leaf samples to be obtained within a range of 0.25 to 3%. In conclusion, this study proposes for the first time a corrective factor in order to quantify the total artemisinin content of A. annua leaves with TLC.
Reversible bio-inspired chemical hydrogen storage systems accumulate electrical energy in the form of electrons and proton ions located on biomolecules or bio-like storage molecules. Electro-active biomolecules (EAB) in Yeast media show such behavior: 2e -?? . The power characteristics of microbial fuel cell stacks equipped with such bio-inspired hydrogen storage systems were examined. E. coli cultures charged these bio-inspired separate chemical hydrogen storage units up to E = 0.50 ± 0.06 V; cell potentials increased proportionally in serial double, triple, and quadruple hydrogen storage stacks up to E OCV = 1.98 V; the maximum power densities that were obtained improved proportionally with stack length by an increment of 1.4. The bio-inspired chemical hydrogen storage principle is of great interest for application in low-cost batteries that store renewable energy.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.