SARS-CoV-2 as a positive-sense single-stranded RNA coronavirus caused the global outbreak of COVID-19. The main protease (Mpro) of the virus as the major enzyme processing viral polyproteins ...contributed to the replication and transcription of SARS-CoV-2 in host cells, and has been characterized as an attractive target in drug discovery. Herein, a set of 1,4-naphthoquinones with juglone skeleton were prepared and evaluated for the inhibitory efficacy against SARS-CoV-2 Mpro. More than half of the tested naphthoquinones could effectively inhibit the target enzyme with an inhibition rate of more than 90% at the concentration of 10 μM. In the structure-activity relationships (SARs) analysis, the characteristics of substituents and their position on juglone core scaffold were recognized as key ingredients for enzyme inhibitory activity. The most active compound, 2-acetyl-8-methoxy-1,4-naphthoquinone (15), which exhibited much higher potency in enzyme inhibitions than shikonin as the positive control, displayed an IC50 value of 72.07 ± 4.84 nM towards Mpro-mediated hydrolysis of the fluorescently labeled peptide. It fit well into the active site cavity of the enzyme by forming hydrogen bonds with adjacent amino acid residues in molecular docking studies. The results from in vitro antiviral activity evaluation demonstrated that the most potent Mpro inhibitor could significantly suppress the replication of SARS-CoV-2 in Vero E6 cells within the low micromolar concentrations, with its EC50 value of about 4.55 μM. It was non-toxic towards the host Vero E6 cells under tested concentrations. The present research work implied that juglone skeleton could be a primary template for the development of potent Mpro inhibitors.
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•Discovery of juglone and related naphthoquinones as potent SARS-CoV-2 Mpro inhibitors•Expanding structure-activity relationships of 1,4-naphthoquinones as Mpro inhibitors•Identifying the most potent Mpro inhibitor (Compd. 15) as an antiviral candidate
Pd–Cu catalysis is combined with in situ electrolytic H2 evolution for NO3 – reduction with protonated polypyrrole (PPy) as a cathode. The surface of PPy is not only beneficial for H2 evolution, but ...exclusive for NO3 – adsorption, and thus inhibits NO3 – reduction. Meanwhile, the in situ H2 generation exhibits a much higher utilization efficiency because of the smaller bubble size and higher dispersion. The Pd–Cu catalysts with the ratios of 6:1 and 4:1 exhibit the highest NO3 ––N removal (100%) and N2 selectivity (93–95%) after 90 min. In comparison with the results obtained with other cathode materials (Ti, Cu, Co3O4, and Fe2O3) and obtained by other researchers, the new process shows a faster NO3 ––N reduction rate and much higher N2 selectivity. However, the O2 generated on the anode can oxidize Cu to Cu2O that may work as the catalyst for NO3 ––N reduction to NH4 +–N by H2, resulting in more than 60% NH4 +–N generated without a proton exchange membrane. Both the PPy film and Pd–Cu catalyst exhibit good stability and there is no Cu2+ or Pd2+ in solution after reaction. Real industrial wastewater is further treated in this system, the NO3 ––N is reduced from 670 mg L–1 to less than 100 mg L–1 in 90 min, and only little amount of NH4 +–N is generated.
Ammonia oxidation was essential in nitrogen recycle, and electrochemical oxidation with artificial, none-noble, robust, high selective ammonia oxidation catalyst was quite attractive while bimetallic ...Ni-Cu hydroxide, NixCu1-x hydroxide, is known to be a quite reactive ammonia oxidation catalyst by previous work. Here we identify the role of Cu site in Ni-Cu hydroxide/oxyhydroxide for its electrochemical oxidation of ammonia. CV and Tafel results revealed that the ammonia oxidation was catalyzed by NiOOH at high onset potential (1.52 V vs. RHE), which was high activity, while the doping of Cu site lowered the onset potential to 1.40 V and achieved a lower Tafel slope. EIS results revealed a large resistance on Cu(OH)2 while NiOOH was proved much more conductive for electron transfer. The in-situ FTIR further revealed that the ammonia oxidation on Cu(OH)2 follows -N intermediate oxidation mechanism with a detection of the nitrite formation on Cu(OH)2. This route was totally different from that on NiOOH which follows -N2Hy intermediate dehydrogenation mechanism. The performance on Ni0.8Cu0.2 hydroxide/oxyhydroxide was proved with confidence robust and high selective during long-time electrolysis experiments. 98% of ammonia was electrochemical oxidized into nitrite on Ni0.8Cu0.2 oxyhydroxide at 1.53 V vs. RHE, indicating a very similar route with Cu(OH)2 but even much more robust comparing with that on Cu(OH)2 or NiOOH. The results also suggested that Cu sites were responsible for high selectivity towards nitrite via -N intermediate while Ni sites charged for catalyzing and played a role of electron transfer tunnel on bimetallic Ni-Cu oxyhydroxide during electrochemical ammonia oxidation.
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•98.0–99.1% ammonia to nitrite and 0.22 mmol L−1 h−1·cm−2-oxidation rate on Ni-Cu oxyhydroxide.•In-situ FTIR tests proved -Nad oxidation pathway on Ni-Cu oxyhydroxide.•Cu sites were responsible for high selectivity towards nitrite.
•CuO NPs feeding in 5–20 mg L−1 could induce Anammox in partial nitrification system.•CuO NPs supplied as the attached carrier for the survival of AAOB and enhanced the quorum sensing.•CuO NPs in ...50 mg L−1 could suppress the nitrogen removal of CANON process.•CuO NPs in 1–5 mg L−1 was profitable for AOB and PN process.•Half of CuO NPs was discharged while the EPS adsorbed most of the NPs remained in the system.
Anaerobic ammonium oxidation (Anammox) was an innovative process for nitrogen removal. In this study, CuO nanoparticles (NPs) was step-wise increasingly added to an MBR-based partial nitrification system, to investigate its feasibility for inducing Anammox and establishing autotrophic nitrogen removal system. Results showed that when CuO NPs was elevated to 5 mg L−1, Anammox was successfully induced. The relative abundance of Nitrosomonas reached 13.73% while Candidatus Kuenenia increased to 4.79% from 0.46%, these two bacteria cooperatively contributed to the autotrophic nitrogen removal and improved the nitrogen removal rate (NRR) to 0.56 kg m-3 d−1 in 20 mg L−1 NPs. However, 50 mg L−1 NPs deeply suppressed the functional bacteria and decreased NRR to 0.14 kg m-3 d−1. Finally, the NPs removal, transformation and adsorption in the system were evaluated. It was concluded that CuO NPs in low concentration (5 mg L−1) was effective for inducing Anammox and contributed to the survival of Anammox bacteria. The mechanism for inducing Anammox was attributed to the aggregation of CuO NPs which enabled the attached growth of AAOB as well as the suitable survival condition supplied by MBR.
Mn3O4-Fe2O3 composite catalysts are in-situ synthesized via advanced oxidation followed by modifying with hydrochloric acid to improve the catalytic toluene oxidation performance. Mn3O4-Fe2O3 ...modified with 1.0 M HCl (A-1.0) exhibited best activity of toluene oxidation. The temperature of 50% toluene conversion is 245 °C and the temperature of 90% conversion is 279 °C. There are much more abundant surface lattice oxygen species and higher amount of high valence manganese and iron ions on A-1.0 catalyst, which are beneficial for improving catalytic activity. In-situ DRIFTs indicated that benzaldehyde and benzoic acid are main intermediate products on A-1.0 catalyst during toluene oxidation.
•Mn3O4-Fe2O3 catalyst is in-situ synthesized via advanced oxidation using K2FeO4 and MnSO4.•Acid-etching modified Mn3O4-Fe2O3 with different concentration of HCl showed improving catalytic performance for toluene oxidation.•Mn3O4-Fe2O3 modified with 1.0 M HCl etching exhibited the best activity of toluene oxidation.•In-situ DRIFTs result indicated that benzaldehyde and benzoic acid were main intermediate products during toluene oxidation.
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▶ 15%-Mn/γ-Fe2O3-250 showed an excellent capacity for elemental mercury capture. ▶ SO2 showed an insignificant effect on Hg0 capture at lower temperatures. ▶ 15%-Mn/γ-Fe2O3-250 can be ...magnetically separated from the fly ash.
A series of Mn/γ-Fe2O3 were synthesized to capture elemental mercury from the flue gas. Mn4+ cations and cation vacancies on the surface played important roles on elemental mercury capture by Mn/γ-Fe2O3. Furthermore, the reaction route of elemental mercury oxidization was dependent on the ratio of Mn4+ cations to cation vacancies. As a result, the capacities of 15%-Mn/γ-Fe2O3-250 for elemental mercury capture were generally higher than those of 30%-Mn/γ-Fe2O3-400. SO2 mainly reacted with ≡FeIII–OH and only a small amount of ≡Mn4+ reacted with SO2, so the presence of a high concentration of SO2 resulted in an insignificant effect on elemental mercury capture by 15%-Mn/γ-Fe2O3-250 at lower temperatures. The capacities of 15%-Mn/γ-Fe2O3-250 for elemental mercury capture in the presence of 2.8gNm−3 of SO2 were more than 2.2mgg−1 at <200°C. Meanwhile, 15%-Mn/γ-Fe2O3-250 can be separated from the fly ash using magnetic separation, leaving the fly ash essentially free of sorbent and adsorbed HgO. Therefore, 15% Mn/γ-Fe2O3-250 may be a promising sorbent for elemental mercury capture.
An ultrasensitive electrochemical biosensor to detect trace Hg
2+
in environmental samples was developed utilizing nanogold-decorated magnetic reduced graphene oxide (MrGO-AuNPs), exonuclease ...III-assisted target cycle (Exo III-ATC) and hybridization chain reaction (HCR) synergistic triple signal amplification. The MrGO-AuNPs is a superior carrier for capture DNA (cDNA) and acts as magnetic media for automatic separation and adsorption. This innovative utilization of the magnetism and improved sensing efficiency obviates the need for direct modification and repeated polishing of the working electrode. Additionally, the three DNA hairpins (cDNA, methylene blue (MB) labeled HP1 and HP2) further contribute to biosensor specificity and selectivity. When cDNA captures Hg
2+
, it activates Exo III-ATC due to the formation of a sticky end in the cDNA stem via thymine-Hg
2+
-thymidine (T-Hg
2+
-T), this leads to the hydrolysis of self-folded cDNA by Exo III-ATC to form “key” DNA (kDNA). The kDNA subsequently initiates HCR, resulting in massive super-sandwich structures (kDNA-HP1/HP2
n
carrying signaling molecules on MrGO-AuNPs, and this overall structure serves as a signal probe (SP). Leveraging magnetic adsorption, the SP was automatically adsorbed onto the magneto-glass carbon electrode (MGCE), generating an amplified signal. This biosensor’s detection limit (LOD) was 3.14 pmol/L, far below the limit of 10 nmol/L for mercury in drinking water set by the US EPA. The biosensor also showed excellent selectivity when challenged by interfering ions, and the results of its application in actual samples indicate that it has good potential for practical applications in environmental monitoring.
A TiO2/Ti–Pt photo fuel cell (PFC) was established to generate electricity and degrade organic pollutants simultaneously. The electricity generation was optimized through investigation the influences ...of photoanode calcination temperature and dissolve oxygen on the resistances existing in PFC. TiO2 light quantum yield was also improved in PFC which resulted in a higher PC degradation efficiency. Two kinds of real textile wastewaters were also employed in this PFC system, 62.4% and 50.0% Coulombic efficiency were obtained for 8 h treatment. These refractory wastewaters with high salinity may become good fuels in PFC because a) TiO2 has no selectivity and can degrade nearly any organic substance, b) no more electrolyte is needed due to the high salinity, c) the energy in wastes can be recovered to generate electricity. The electricity generated by the PFC was further applied on a TiO2/Ti rotating disk photoelectrocatalytic reactor. A bias voltage between 0.6 and 0.75 V could be applied and the PC degradation efficiency was significantly improved. This result was similar with that obtained by a 0.7 V DC power.
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•A PFC was established to generate electricity and degrade pollutants simultaneously.•The influences of calcination temperature and dissolved oxygen were investigated.•The photo quantum yield and PC degradation efficiency were also enhanced in PFC.•Real textile wastewaters were also utilized as fuel without electrolyte addition.•The electricity generated by PFC was employed as bias voltage in a PEC reactor.
In order to facilitate the removal of elemental mercury (Hg0) from coal-fired flue gas, catalytic oxidation of Hg0 with manganese oxides supported on inert alumina (α-Al2O3) was investigated at lower ...temperatures (373−473 K). To improve the catalytic activity and the sulfur-tolerance of the catalysts at lower temperatures, several metal elements were employed as dopants to modify the catalyst of Mn/α-Al2O3. The best performance among the tested elements was achieved with molybdenum (Mo) as the dopant in the catalysts. It can work even better than the noble metal catalyst Pd/α-Al2O3. Additionally, the Mo doped catalyst displayed excellent sulfur-tolerance performance at lower temperatures, and the catalytic oxidation efficiency for Mo(0.03)−Mn/α-Al2O3 was over 95% in the presence of 500 ppm SO2 versus only about 48% for the unmodified catalyst. The apparent catalytic reaction rate constant increased by approximately 5.5 times at 423 K. In addition, the possible mechanisms involved in Hg0 oxidation and the reaction with the Mo modified catalyst have been discussed.
•The factors that influenced desulfurization efficiency were investigated.•The reaction routes of model sulfur compounds were proposed.•ILs maintained their original structures after ...regeneration.•Desulfurization reaction by the ERDS process fitted the pseudo-first-order kinetics.•The ERDS process could be used as a promising method for gasoline desulfurization.
A novel integrated process of extraction with ionic liquid (IL) and reductive desulfurization by sodium borohydride (NaBH4) was presented for gasoline desulfurization. The factors that influenced desulfurization efficiency were investigated and desulfurization efficiency reached more than 97% for model gasoline and more than 93% for real gasoline. The components of model gasoline after desulfurization were analyzed by gas chromatography/mass spectrometry (GC/MS) and the reaction routes of model sulfur compounds were proposed. The contents of sulfur, boron and nickel in aqueous solutions were analyzed by Chinese standard method or inductively coupled plasma (ICP). Furthermore, the structures of original and recycled ILs were analyzed by nuclear magnetic resonance (NMR) and the desulfurization performance of recycled ILs was investigated. Results indicated that ILs maintained their original structures after regeneration. Finally, desulfurization kinetics was also probed and results showed that desulfurization reactions of both model sulfur compounds and real gasoline could be treated as pseudo-first-order reactions.
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