The bis(imino)pyridine iron complex, for the first time, is developed as an effective metal carbene catalyst for carbene transfer reactions of donor-acceptor diazo compounds. Its broad catalytic ...capability is demonstrated by a range of metal carbene reactions, from cyclopropanation, cyclopropenation, epoxidation, and Doyle-Kirmse reaction to O-H insertion, N-H insertion, and C-H insertion reactions. The asymmetric cyclopropanation of styrene and methyl phenyldiazoacetate was successfully achieved by the new chiral bis(imino)pyridine iron catalyst, which delivers a new gateway for the development of chiral iron catalysis for metal carbene reactions.
The bis(imino)pyridine iron complex, for the first time, is developed as an effective metal carbene catalyst for carbene transfer reactions of donor-acceptor diazo compounds.
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IJS, KILJ, NUK, UL, UM, UPUK
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•A novel optosensor was developed based on UCNPs decorated with different metal ions.•The sensor displayed a high selectivity and high sensitivity for catecholamines (CAs), dopamine, ...and epinephrine.•It gave an excellent analytical performance with low LODs and reproducibility.•It was employed for sensing CAs in biological fluids with satisfactory recoveries.
We developed a novel optical sensor for sensitive and selective detection of catecholamines based on upconversion nanoparticles (UCNPs) decorated with different metal ions (UCNP-Men+). 1,2-ethanedithiol was chosen as a surface additive to synthesize the NaLuGdF4:Yb3+/Er3+ UCNPs by one-step at 200 °C. The as-prepared UCNPs exhibited a strong emission under the continuous excitation at 980 nm. It was found that catecholamines could be more effectively detected in the presence of UCNP-Fe3+, whereas, dopamine and epinephrine were detected selectively using UCNP-Li+ and UCNP-Cu2+ sensors, respectively. Under the optimum conditions, the limit of detections (LODs) for catecholamines, dopamine, and epinephrine are 2.8, 2.5, and 2.4 nM, respectively, with good linearity in the range of 5–320 nM for total catecholamines and 5–30 nM for dopamine and epinephrine. The developed method has been successfully applied to detect dopamine and epinephrine in human urine samples with good accuracy and satisfactory recovery.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A
bstract
Studies of dark matter lie at the interface of collider physics, astrophysics and cosmology. Constraining models featuring dark matter candidates entails the capability to provide accurate ...predictions for large sets of observables and compare them to a wide spectrum of data. We present a framework which, starting from a model Lagrangian, allows one to consistently and systematically make predictions, as well as to confront those predictions with a multitude of experimental results. As an application, we consider a class of simplified dark matter models where a scalar mediator couples only to the top quark and a fermionic dark sector (i.e. the simplified top-philic dark matter model). We study in detail the complementarity of relic density, direct/indirect detection and collider searches in constraining the multi-dimensional model parameter space, and efficiently identify regions where individual approaches to dark matter detection provide the most stringent bounds. In the context of collider studies of dark matter, we point out the complementarity of LHC searches in probing different regions of the model parameter space with final states involving top quarks, photons, jets and/or missing energy. Our study of dark matter production at the LHC goes beyond the tree-level approximation and we show examples of how higher-order corrections to dark matter production processes can affect the interpretation of the experimental results.
Iron cobalt oxides, such as typical FeCo2O4 and CoFe2O4, are two spinel structured transitional metal oxide materials with excellent electrochemical performance. As the electrodes, they have been ...widely applied in the current energy storage and conversion processes such as supercapacitors, Lithium-ion batteries and fuel cells. Based on synthesis approaches and controlled conditions, these two materials exhibited broad morphologies and nanostructures and thus distinct electrochemical performance. Some of them have shown promising applications as electrodes in energy storage and conversion. The incorporation with other materials to form composites further improved their performance. This review briefly summarized the recent applications of FeCo2O4 and CoFe2O4 in energy storage and conversion, current understandings on mechanisms and especially the relevance of morphologies and structures and composites to electrochemical performance. Some recommendations were finally put forward addressing current issues and future prospects on electrodes of FeCo2O4 and CoFe2O4 based materials in energy storage and conversion, implying there was still space to further optimize their performance.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Anaerobic digestion is used for the treatment of animal manure by generating biogas. Heavy metals cause environmental pollutions and co-select for antimicrobial resistance. We evaluated the impact of ...mesophilic anaerobic digestion of cattle manure (CM), swine manure (SM) and poultry litter (PL) on the concentrations of seven tetracycline
(A),
(B),
(G),
(M),
(O),
(Q), and
(W), macrolide
(B), methicillin (
A and
C), copper (
B,
A,
D, and
B) and zinc (
C) resistance genes, and three bacterial species (
,
spp. and
). The total bacterial population and total abundance of the seven
genes significantly increased in the three manure types after digestion. Concentration of
(M) was strongly correlated with that of
(B) and enterococci. As concentration of tetracyclines declined during anaerobic digestion, that of four
genes (A, B, Q, and W) and 16S rRNA increased, that of
(M) decreased, and that of
(G) and
(O) did not change. Concentrations of
B and
A did not change; while that of
D did not change in the PL, it increased in the SM and CM. While the concentration of enterococci remained unchanged in CM, it significantly increased in the PL and SM. Concentrations of
B significantly increased in the three manure types. While concentrations of
significantly increased in the CM and PL, that of SM was not affected. Concentrations of
C significantly increased in all manure types after digestion; while
A concentrations did not change in the SM, they significantly increased in CM and PL. While concentration of
C remained low in the CM, it increased in the PL but declined in the SM. In conclusion, while mesophilic anaerobic digestion of animal manure decreased concentration of tetracyclines, it increased the concentrations of total bacteria,
genes,
, enterococci and
and methicillin resistance genes. It did not have any effect on concentrations of heavy metals; concentrations of heavy metal resistance genes either increased or remained unaffected depending on the animal species. This study showed the need for post-digestion treatments of animal manure to remove bacteria, antibiotic resistance genes, heavy metals and their resistance genes.
The impact of anaerobic digestion of animal waste on the persistence of antibiotic resistance genes (ARGs) and antibiotics is not widely studied. Two identical, 800‐L digesters seeded with swine ...slurry were followed up to 100 d in three separate trials. The trials received varying amounts of antibiotic‐free corn (Zea mays L.) mixed with water to maintain the digestion process. Biogas production, seven tetracycline resistance (tet) genes, and three tetracyclines and their transformation products were measured. Biogas production proportionally increased as the feeding loads increased between trials. In Trial 1, log10 tet gene copies showed small but statistically significant (P < 0.01) increases during digestion. In Trial 2, anaerobic digestion did not have a significant (P > 0.05) effect except for significant reductions in tetB (P < 0.0001) and tetG (P = 0.0335) log10 gene copies. In Trial 3, which received the highest amount of corn mix, log10 copies of the 16S ribosomal RNA and the tet genes significantly (P < 0.0001) reduced over time during digestion. Up to 36 μg L−1 tetracycline, 112 μg L−1 chlortetracycline, 11.9 mg L−1 isochlortetracycline, and 30 μg L−1 4‐epitetracycline were detected both in the liquid and solid digestates. Results of this study revealed that although anaerobic digestion of swine waste can produce useful biogas, it does not result in complete removal of bacteria, ARGs, and antibiotics regardless of differences in the feeding loads between trials. Further effluent and sludge treatments are required prior to their downstream use in crop production to minimize emergence and environmental dissemination of antimicrobial‐resistant bacteria through animal manure.
Core Ideas
Anaerobic digestion did not completely remove resistance genes from swine waste.
Tetracycline antibiotics were detected from 30 μg L−1 to 11.9 mg L−1.
Further waste treatments are required to reduce the spread of resistance genes.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
We investigated the anaerobic degradation of tetracycline antibiotics (tetracycline TC, oxytetracycline OTC and chlortetracycline CTC) in swine, cattle, and poultry manures. The manures were ...anaerobically digested inside polyvinyl chloride batch reactors for 64 days at room temperature. The degradation rate constants and half-lives of the parent tetracyclines were determined following first-order kinetics. For CTC the fastest degradation rate was observed in swine manure (k = 0.016 ± 0.001 d
−1
; half-life = 42.8 days), while the slowest degradation rate was observed in poultry litter (k = 0.0043 ± 0.001 d
−1
; half-life = 161 days). The half-lives of OTC ranged between 88.9 (cattle manure) and 99.0 days (poultry litter), while TC persisted the longest of the tetracycline antibiotics studied with half-lives ranging from 92.4 days (cattle manure) to 330 days (swine manure). In general, the tetracyclines were found to degrade faster in cattle manure, which had the lowest concentrations of organic matter and metals as compared to swine and poultry manures. Our results demonstrate that tetracycline antibiotics persist in the animal manure after anaerobic digestion, which can potentially lead to emergence and persistence of antibiotic resistant bacteria in the environment when anaerobic digestion byproducts are land applied for crop production.
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BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Increased demand for animal protein is met by increased food animal production resulting in large quantities of manure. Animal producers, therefore, need sustainable agricultural practices to protect ...environmental health. Large quantities of antimicrobials are used in commercial food animal production. Consequently, antimicrobial-resistant bacteria and the resistance genes emerge and are excreted through feces. Manure management is essential for the safe disposal of animal waste. Lagoons, with or without covers, and anaerobic digesters, with the primary purpose of methane production, and composting, with the primary purpose of producing organic fertilizer, are widely used methods of manure treatment. We reviewed manure management practices and their impact on tetracycline resistance genes. Lagoons are maintained at ambient temperatures; especially uncovered lagoons are the least effective in removing tetracycline resistance genes. However, some modifications can improve the performance of lagoons: sequential use of uncovered lagoons and the use of covered lagoons resulted in a one-log reduction, while post-treatments such as biofiltration following covered lagoon treatment resulted in 3.4 log reduction. Mesophilic digestion of animal manure did not have any significant effect; only a 0.7 log reduction in tet(A) was observed in one study. While thermophilic anaerobic digesters are effective, if properly operated, they are expensive for animal producers. Aerobic thermophilic composting is a promising technology if optimized with its economic benefits. Composting of raw animal manure can result in up to a 2.5 log reduction, and postdigestion composting can reduce tetracycline resistance gene concentration by >80%. In general, manure management was not designed to mitigate antimicrobial resistance; future research is needed to optimize the economic benefits of biogas or organic fertilizer on the one hand and for the mitigation of foodborne pathogens and antimicrobial resistance on the other.
An increase in the number of independent breweries and distilleries has led to an increase in the amount of spent grains with inadequate means of disposal. One option for disposal is as feedstock for ...anaerobic digestion if digester stability is ensured. In this study, brewers’ spent grain and distillers’ spent grain were used as substrate for anaerobic digestion for 32 weeks. The digestate was treated by recirculation through a silicone hose located in an external tank filled with saline solution. The hose served as a permeable membrane allowing for the passage of gases. The recirculation tanks were fitted with check valves to maintain three pressure/gas regimes: 26 mm Hg N2, 26 mm Hg aeration or 100 mm Hg aeration. A fourth digester was operated with no recirculation as the control. These treatments were chosen to determine if differences in digester stability, wastewater treatment efficiency, and biogas production could be detected. A combination of dairy and swine manure was used as seeding to provide a methanogenic consortium and bicarbonate buffering. However, despite trying to provide for adequate initial bicarbonate buffering, all four digesters had low initial buffering and consequently low pH as short-chain fatty acids accumulated. After six weeks, bicarbonate buffering and pH increased as methane production increased, and short-chain fatty acids decreased. Later, despite the fluxes of O2 and N2 across the silicone membrane being very low, differences between the various treatments were noted. The pH of the digestate treated by N2 recirculation was lower than the other digesters and decreased further after distillers’ spent grain was substituted for brewers’ spent grain. Aeration at a pressure of 26 mm Hg and 100 mg Hg increased biogas production compared to other treatments but only significantly so at 100 mm Hg. These results suggest that partial purging of dissolved gases in anaerobic digestate by the small fluxes of N2 or O2 across a permeable membrane may affect digester performance.
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