Agricultural management techniques such as fertilizer or manure application have substantial influence on NH3 and N2O emissions and, by understanding this influence, management strategies can be developed to reduce them. An experiment was conducted in a greenhouse at Hunan Agricultural University during 2012 to 2013, to investigate effects of different fertilizers on NH3 and N2O emissions. The treatments included control without fertilizer (CK), swine composting fertilizer (SC), stored swine manure fertilizer (SS), and chemical fertilizer (FC). The fluxes of NH3 and N2O were collected by venting method and static-chamber method, respectively. The results showed that during the spinach growth season, compared with FC, loss of both NH3 and N2O for SC were reduced by 52.9% and 95.12%, respectively(P<0.01). However, loss of NH3 for SS increased by 24.8%, and loss of N2O reduced by 48.8% compared with FC. Loss rate of NH3 were SS (10.97%) > FC (4.19%) > SC(2.74%), and emission coefficient for N2O were FC(4.50%) > SC(2.21%) > SS(0.60%). Yield and utilization of nitrogen for SC were reduced by 19.61% and 13.20% compared with FC, respectively, but not significantly; and significantly reduced by 27.9% and 40.0% compared with SS, respectively. Loss of gases (NH3 and N2O) for SC were 1.83%, which was the lowest, while utilization of nitrogen for SC was 13.20%, similar with FC. Greenhouse temperature was not the critical factor during the spinach planting in winter, but soil water was. Therefore, optimizing manure management could reduce ammonia volatilization and N2O emission loss without decreasing vegetables production, and the present data indicated that SC would be optimal for better yields with reduced ammonia volatilization and N2O emission loss.
We demonstrate a water electrolysis device consisting of two 10 cm 2 Ni/aramid flexible electrodes with a Si solar cell with >13% solar-to-hydrogen efficiency over 120 hours stability.
We identify the function of CuO impurities in CuBi2O4 photocathodes significantly improving the photoelectrochemical water reduction efficiency. Spectroelectrochemical photo/voltage-induced absorption spectroscopies are employed to investigate the charge carrier dynamics of pure, CuO-impure, and CuO-covered CuBi2O4 photocathodes during photoelectrochemical water reduction, in comparison with the CuO/FTO for electrochemical water reduction. Electrons after photoexciation are found to accumulate at the surface CuO in both CuO-covered and impure CuBi2O4 photocathodes, rather than directly reducing water from the CuBi2O4 conduction band. A rate law analysis is employed to compare the kinetics of water reduction in CuO/FTO electrochemically and CuBi2O4 photoelectrochemically, showing a faster water reduction rate constant in CuO than CuBi2O4. The kinetic comparison demonstrates that the CuO impurity functions as a cocatalyst on the surface of CuBi2O4 during water reduction due to the faster kinetics. Our results demonstrate the importance of considering the catalytic function of surface impurities responsible for the enhancement of water reduction efficiency.
Abstract A novel biomaterial based on polyurethane (PU) was prepared through physical incorporation of lysine‐containing copolymer to improve its hemocompatibility and surface recognition of plasminogen. The lysine‐containing copolymer was synthesized via the copolymerization of 2‐ethylhexyl methacrylate (EHMA), oligo (ethylene glycol) methyl ether methacrylate (OEGMA) and 6‐ tert ‐butoxycarbonyl amino‐2‐(2‐methyl‐acryloylamino)‐hexanoic acid tert ‐butyl ester (Lys(P)MA), followed by the deprotection of COOH and ε ‐NH 2 groups on lysine residues in the copolymer. The composition of the copolymer can be adjusted by varying the monomer feed ratio. The three components contribute to improving the compatibility with PU, resistance to nonspecific protein adsorption and specific binding of plasminogen, respectively. The binding capacity towards plasminogen increased with the lysine content in the copolymer. This approach illustrates a simple way for the generation of novel biomaterials with improved hemocompatibility and surface recognition of specific biomolecules.
Surface back electron/hole recombination limits the water oxidation efficiency in BiVO 4 due to slow water oxidation and fast recombination. TiO 2 is less affected due to faster water oxidation that avoids surface recombination.
Operando spectroelectrochemistry is employed to identify the electrochemical water oxidation reaction kinetics on metallic nickel in comparison with nickel oxyhydroxide. The nickel oxide on metallic nickel shows a spectroelectrochemical feature of the active species similar to the nickel oxyhydroxide during water oxidation. This amorphous oxide on the surface of metallic nickel is a crucial catalyst exhibiting a higher water oxidation activity in both rate constants and turnover frequency than the electrodeposited nickel oxyhydroxide by 3-fold for water oxidation, using a population-based rate-law analysis. These surface characterization and kinetic results reveal the underlying mechanism of the higher water oxidation efficiency of nickel oxide derived from metallic nickel than that of the electrodeposited nickel oxyhydroxide. These results also emphasize the importance of surface oxidized nickel, in terms of the structural and chemical consideration, for the optimization of electrodes toward efficient water oxidation using nickel or nickel-containing materials.
In order to investigate the performance of nitrogen and phosphorus removal of the sulfur/limestone system from low C/N municipal sewage, a sulfur/limestone packed column reactor fed with synthetic wastewater, and operated in the way of anaerobic biological filter was constructed. The effects of HRT, initial concentration of phosphate, pH and temperature on nitrogen and phosphorus removal were studied. The results showed that with influent of NO3(-) -N 30 mg/L, PO4(3-) -P 15 mg/L, the optimal HRT value was 6 h, and removal rates of TN and phosphorus were 100% and 44.64% respectively. Initial concentration of phosphate and initial pH had a significant influence on nitrogen and phosphorus removal. In order to keep nitrogen removal rate higher than 90%, initial concentration of phosphate should not be below 0.4 mg/L; the optimal pH value was 6.5, and removal rates of TN and phosphorus were 91.51% and 47.68% respectively. Temperature had a positive impact on that system, the nitrogen and phosphorus removal rate decreased with decreasing temperature. The nitrate removal efficiency was high in the temperature range of 18-30 degrees C, and the efficiency of phosphorus removal rate reached about 50%, when the temperature was between 25-30 degrees C. The dephosphorization behavior of sulfur/ limestone system correlated closely with autotrophic denitrification process, and the mechanism of phosphate removal of the SLAD system was mainly due to chemical precipitation. The system had the performance of nitrogen and phosphorus removal from low C/N municipal sewage, the highest phosphorus removal rate could reach 50%.
Photoelectrochemical oxidation of methylene blue is investigated, with particular focus on the difference in kinetics and thermodynamics of decoloration and mineralization employing photoinduced absorption spectroscopy. Hematite and titania photoanodes are used for the comparison of both reactions, which is determined to be associated with the depth of the valence band (3.2 vs 2.5 V for titania and hematite, respectively). Methylene blue is mineralized by the titania photoanode, however it is only oxidized to small fragments by hematite. Such difference is related to the valence band potential that provides the thermodynamic driving force for photogenerated holes in both materials. In addition, the kinetic competition of water oxidation is found to occur on titania by controlling the pH of the electrolyte. In the pH 14 electrolyte, mineralization of methylene blue is suppressed due to the faster and dominant kinetics of water oxidation, in contrast to the complete mineralization in the near neutral electrolyte where water oxidation kinetics are modest. These results clearly address the importance considering both thermodynamic and kinetic challenges of methylene blue oxidation, which has been thought to be an easy molecule to oxidize, as the model reaction in the application of photo(electro)catalysis using metal oxides.
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