Passivated phosphorene nanoribbons, armchair (a-PNR), 7 diagonal (d-PNR), and zigzag (z-PNR), were investigated using density 8 functional theory. Z-PNRs demonstrate the greatest quantum size effect, 9 tuning the bandgap from 1.4 to 2.6 eV when the width is reduced from 26 to 6 10 Å. Strain effectively tunes charge carrier transport, leading to a sudden increase 11 in electron effective mass at +8% strain for a-PNRs or hole effective mass at 12 +3% strain for z-PNRs, differentiating the (m h */m e *) ratio by an order of otherwise, we present results using crystal lattices, geometries,

BackgroundAnaerobic digestion has been widely applied to treat the waste activated sludge from biological wastewater treatment and produce methane for biofuel, which has been one of the most efficient solutions to both energy crisis and environmental pollution challenges. Anaerobic digestion sludge contains highly complex microbial communities, which play crucial roles in sludge treatment. However, traditional approaches based on 16S rRNA amplification or fluorescent in situ hybridization cannot completely reveal the whole microbial community structure due to the extremely high complexity of the involved communities. In this sense, the next-generation high-throughput sequencing provides a powerful tool for dissecting microbial community structure and methane-producing pathways in anaerobic digestion.ResultsIn this work, the metagenomic sequencing was used to characterize microbial community structure of the anaerobic digestion sludge from a full-scale municipal wastewater treatment plant. Over 3.0 gigabases of metagenomic sequence data were generated with the Illumina HiSeq 2000 platform. Taxonomic analysis by MG-RAST server indicated that overall bacteria were dominant (~93%) whereas a considerable abundance of archaea (~6%) were also detected in the anaerobic digestion sludge. The most abundant bacterial populations were found to be Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria. Key microorganisms and related pathways involved in methanogenesis were further revealed. The dominant proliferation of Methanosaeta and Methanosarcina, together with the functional affiliation of enzymes-encoding genes (acetate kinase (AckA), phosphate acetyltransferase (PTA), and acetyl-CoA synthetase (ACSS)), suggested that the acetoclastic methanogenesis is the dominant methanogenesis pathway in the full-scale anaerobic digester.ConclusionsIn short, the metagenomic sequencing study of this work successfully dissected the detail microbial community structure and the dominated methane-producing pathways of a full-scale anaerobic digester. The knowledge garnered would facilitate to develop more efficient full-scale anaerobic digestion systems to achieve high-rate waste sludge treatment and methane production.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-015-0218-4) contains supplementary material, which is available to authorized users.

Solar-driven CO 2 reduction by abundant water to alcohols can supply sustainable liquid fuels and alleviate global warming. However, the sluggish water oxidation reaction has been hardly reported to be efficient and selective in CO 2 conversion due to fast charge recombination. Here, using transient absorption spectroscopy, we demonstrate that microwave-synthesised carbon-dots (m CD) possess unique hole-accepting nature, prolonging the electron lifetime (t 50%) of carbon nitride (CN) by six folds, favouring a six-electron product. m CD-decorated CN stably produces stoichiometric oxygen and methanol from water and CO 2 with nearly 100% selectivity to methanol and internal quantum efficiency of 2.1% in the visible region, further confirmed by isotopic labelling. Such m CD rapidly extracts holes from CN and prevents the surface adsorption of methanol, favourably oxidising water over methanol and enhancing the selective CO 2 reduction to alcohols. This work provides a unique strategy for efficient and highly selective CO 2 reduction by water to high-value chemicals.