For over two decades,sulfate reduction with ammonium oxidation(SRAO)had been reported from laboratory experiments.SRAO was considered an autotrophic process mediated by anammox bacteria,in which ammonium as electron d...For over two decades,sulfate reduction with ammonium oxidation(SRAO)had been reported from laboratory experiments.SRAO was considered an autotrophic process mediated by anammox bacteria,in which ammonium as electron donor was oxidized by the electron acceptor sulfate.This process had been attributed to observed transformations of nitrogenous and sulfiirous compounds in natural environments.Results obtained differed largely for the conversion mole ratios(ammonium/sulfate),and even the intermediate and final products of sulfate reduction.Thus,the hypothesis of biological conversion pathways of ammonium and sulfate in anammox consortia is implausible.In this study,continuous reactor experiments(with working volume of 3.8L)and batch tests were conducted under normal anaerobic(0.2<DO<0.5 mg/L)/strict anaerobic(DO<0.2 mg/L)conditions with different biomass proportions to verify the SRAO phenomena and identify possible pathways behind substrate conversion.Key findings were that SRAO occurred only in cases of high amounts of inoculant biomass under normal anaerobic condition,while absent under strict anaerobic conditions for same anammox consortia.Mass balance and stoichiometry were checked based on experimental results and the thermodynamics proposed by previous studies were critically discussed.Thus anammox bacteria do not possess the ability to oxidize ammonium with sulfate as electron acceptor and the assumed SRAO could,in fact,be a combination of aerobic ammonium oxidation,anammox and heterotrophic sulfate reduction processes.展开更多
In the context of the circular economy,the huge amounts of biomass waste should be converted into value-added materials and energy to diminish pollution,atmospheric CO_(2)levels and costly waste disposal.Biological im...In the context of the circular economy,the huge amounts of biomass waste should be converted into value-added materials and energy to diminish pollution,atmospheric CO_(2)levels and costly waste disposal.Biological imaging usually uses expensive and toxic chemicals e.g.,organic dyes,semiconductor quantum dots,calling for safer,greener,cheaper fluorescent probes for biological imaging in vitro and in vivo.In these regards,carbon quantum dots(CQDs)-based fluorescent probes using biomass waste as a precursor may have much higher potential.Here we transformed the biomass waste of peach leaves into value-added fluorescent CQDs through a low-cost and green one-step hydrothermal process.The obtained CQDs show excitation-dependent photoluminescence properties with a fluorescence lifetime of 5.96 ns and a quantum yield of 7.71%without any passivation.In addition,the CQDs have a fine size of 1.9 nm with good hydrophilicity and high fluorescent stability over pH 4.0-11.0 range.Fluorescence imaging of in vitro cell cultures and in vivo with zebrafish show that CQDs possess ultra-low toxicity and remarkable performance for biological imaging.Even when CQDs present at a concentration as high as500μg/m L,the organism can still maintain more than 90%activity both in vitro and in vivo,and present bright fluorescence.The cheaper,greener,ultra-low toxicity CQDs developed in this work is a potential candidate for biological imaging in vitro and in vivo.展开更多
基金This work was supported by the National Natural Science Foundation of China(Nos.51478284,21607110 and 51408387)the National&Local Joint Engineering Laboratory for Municipal Sewage Resource Utilization Technology,Suzhou University of Science and Technology(No.2018KF02).
文摘For over two decades,sulfate reduction with ammonium oxidation(SRAO)had been reported from laboratory experiments.SRAO was considered an autotrophic process mediated by anammox bacteria,in which ammonium as electron donor was oxidized by the electron acceptor sulfate.This process had been attributed to observed transformations of nitrogenous and sulfiirous compounds in natural environments.Results obtained differed largely for the conversion mole ratios(ammonium/sulfate),and even the intermediate and final products of sulfate reduction.Thus,the hypothesis of biological conversion pathways of ammonium and sulfate in anammox consortia is implausible.In this study,continuous reactor experiments(with working volume of 3.8L)and batch tests were conducted under normal anaerobic(0.2<DO<0.5 mg/L)/strict anaerobic(DO<0.2 mg/L)conditions with different biomass proportions to verify the SRAO phenomena and identify possible pathways behind substrate conversion.Key findings were that SRAO occurred only in cases of high amounts of inoculant biomass under normal anaerobic condition,while absent under strict anaerobic conditions for same anammox consortia.Mass balance and stoichiometry were checked based on experimental results and the thermodynamics proposed by previous studies were critically discussed.Thus anammox bacteria do not possess the ability to oxidize ammonium with sulfate as electron acceptor and the assumed SRAO could,in fact,be a combination of aerobic ammonium oxidation,anammox and heterotrophic sulfate reduction processes.
基金supported by the National Natural Science Foundation of China(Nos.21976116 and 52161145409)the Shaanxi Science and Technology Program(No.2020KWZ-005)+1 种基金SAFEA of China(“Belt and Road”Innovative Exchange Foreign Expert Project,No.DL2021041001L)Researchers Supporting Project number(No.RSP-2021/149),King Saud University,Riyadh,Saudi Arabia。
文摘In the context of the circular economy,the huge amounts of biomass waste should be converted into value-added materials and energy to diminish pollution,atmospheric CO_(2)levels and costly waste disposal.Biological imaging usually uses expensive and toxic chemicals e.g.,organic dyes,semiconductor quantum dots,calling for safer,greener,cheaper fluorescent probes for biological imaging in vitro and in vivo.In these regards,carbon quantum dots(CQDs)-based fluorescent probes using biomass waste as a precursor may have much higher potential.Here we transformed the biomass waste of peach leaves into value-added fluorescent CQDs through a low-cost and green one-step hydrothermal process.The obtained CQDs show excitation-dependent photoluminescence properties with a fluorescence lifetime of 5.96 ns and a quantum yield of 7.71%without any passivation.In addition,the CQDs have a fine size of 1.9 nm with good hydrophilicity and high fluorescent stability over pH 4.0-11.0 range.Fluorescence imaging of in vitro cell cultures and in vivo with zebrafish show that CQDs possess ultra-low toxicity and remarkable performance for biological imaging.Even when CQDs present at a concentration as high as500μg/m L,the organism can still maintain more than 90%activity both in vitro and in vivo,and present bright fluorescence.The cheaper,greener,ultra-low toxicity CQDs developed in this work is a potential candidate for biological imaging in vitro and in vivo.
