RESUMEN
Anaerobic microorganisms of the Geobacter genus are effective electron sources for the synthesis of nanoparticles, for bioremediation of polluted water, and for the production of electricity in fuel cells. In multistep reactions, electrons are transferred via iron/heme cofactors of c-type cytochromes from the inner cell membrane to extracellular metal ions, which are bound to outer membrane cytochromes. We measured electron production and electron flux rates to 5×105 â e s-1 per G.â sulfurreducens. Remarkably, these rates are independent of the oxidants, and follow zero order kinetics. It turned out that the microorganisms regulate electron flux rates by increasing their Fe2+ /Fe3+ ratios in the multiheme cytochromes whenever the activity of the extracellular metal oxidants is diminished. By this mechanism the respiration remains constant even when oxidizing conditions are changing. This homeostasis is a vital condition for living systems, and makes G.â sulfurreducens a versatile electron source.
RESUMEN
Lignin isolated from agricultural residues is a promising alternative for petroleum-based polymers as feedstocks in development of antimicrobial materials. A polymer blend based on silver nanoparticles and lignin-toluene diisocyanate film (AgNPs-Lg-TDIs) was generated from organosolv lignin and silver nanoparticles (AgNPs). Lignin was isolated from Parthenium hysterophorus using acidified methanol and used to synthesize lignin capped silver nanoparticles. Lignin-toluene diisocyanate film (Lg-TDI) was prepared by treating lignin (Lg) with toluene diisocyanate (TDI) followed by solvent casting to form films. Functional groups present and thermal properties of the films were evaluated using Fourier-transform infrared spectrophotometry (FT-IR), thermal gravimetry (TGA), and differential scanning calorimetry (DSC). Scanning electron microscopy (SEM), UV-visible spectrophotometry (UV-Vis), and Powder X-ray diffractometry (XRD) were used to assess the morphology, optical properties, and crystallinity of the films. Embedding AgNPs in the Lg-TDI films increased the thermal stability and the residual ash during thermal analysis, and the presence of powder diffraction peaks at 2θ = 20, 38, 44, 55, and 58° in the films correspond to lignin and silver crystal planes (111). SEM micrographs of the films revealed the presence of AgNPs in the TDI matrix with variable sizes of between 50 to 250 nm. The doped films had a UV radiation cut-off at 400 nm as compared to that of undoped films, but they did not exhibit significant antimicrobial activity against selected microorganisms.
RESUMEN
Wild indigenous vegetables make considerable contributions to food baskets among subsistence farmers in sub-Saharan Africa. The aim of this study was to evaluate the proximate analysis, mineral composition, vitamin C content, ß-carotene content, and GC-MS profile of crude methanolic extracts of Asystasia mysorensis and Sesamum angustifolia. Crude extracts obtained through sequential extraction using ethyl acetate and methanol were screened for the presence of secondary metabolites. Functional groups present were determined with a Shimadzu FT-IR spectrophotometer, while ß-carotene content and ascorbic acid content were evaluated using a Shimadzu HPLC and Shimadzu UV-VIS spectrophotometer, respectively. Secondary metabolites present in the extracts were determined qualitatively using a Shimadzu GC-MS system equipped with a NIST spectral database. From the results obtained, the two plants could supply the recommended daily requirement for micronutrient and vitamin C content needed for a healthy diet. The total phenolic and flavonoid contents in S. amgustifolia were higher as compared to A. myorensis; hence, their consumption is highly beneficial as some compounds identified in the GC-MS profile have been reported to have medicinal properties. The findings on the mineral and chemical composition, GC-MS profile of A. mysorensis and S. angustifolia indicate that their consumption may provide the recommended nutritional requirements needed for a healthy diet.
RESUMEN
In this data article, data obtained from an efficient, eco-friendly and low-cost method for the synthesis and recovery of Silver nanoparticles (AgNPs) using ethanolic extracts of Annona muricata fruits and leaves as reducing, stabilizing and capping agents has been reported. 99.7% pure silver nitrate was used as the inorganic ion source. The data was obtained using different spectroscopic and microscopic techniques. The data is presented in form of images, Microsoft excel sheets, graphs,.raw files,.dpt files, PDF files, among others. Methods of analysis and interpretation of the data have also been presented. The data can be most useful to researchers, research students, industrialists and academicians to acquire knowledge on the green synthesis of AgNPs and related applications. The data is deposited in the Mendeley Data Repository as two independent datasets accessible at https://doi.org/10.17632/jkj2x782wh.1 Gavamukulya et al., 2019 and https://doi.org/10.17632/f4mb6b488n.1 Gavamukulya et al., 2019.