Latest ArticlesPlasmodium parasites causing malaria have developed resistance to most of the antimalarials in use, including the artemisinin-based combinations, which are the last line of defense against malaria. This necessitates the discovery of new targets and the development of novel antimalarials. Plasmodium falciparum alanyl aminopeptidase (PfA-M1) and leucyl aminopeptidase (PfA-M17) belong to the M1 and M17 family of metalloproteases respectively and play critical roles in the asexual erythrocytic stage of development. These enzymes have been suggested as potential antimalarial drug targets. Herein we describe the development of peptidomimetic hydroxamates as PfA-M1 and PfA-M17 dual inhibitors. Most of the compounds described in this study display inhibition at sub-micromolar range against the recombinant PfA-M1 and PfA-M17. More importantly, compound 26 not only exhibits potent malarial aminopeptidases inhibitory activities (PfA-M1 Ki = 0.11 ± 0.0002 µmol/L, PfA-M17 Ki = 0.05 ± 0.005 µmol/L), but also possesses remarkable selectivity over the mammalian counterpart (pAPN Ki = 17.24 ± 0.08 µmol/L), which endows 26 with strong inhibition of the malarial parasite growth and negligible cytotoxicity on human cell lines. Crystal structures of PfA-M1 at atomic resolution in complex with four different compounds including compound 26 establish the structural basis for their inhibitory activities. Notably, the terminal ureidobenzyl group of 26 explores the S2′ region where differences between the malarial and mammalian enzymes are apparent, which rationalizes the selectivity of 26. Together, our data provide important insights for the rational and structure-based design of selective and dual inhibitors of malarial aminopeptidases that will likely lead to novel chemotherapeutics for the treatment of malaria.
Reverse water gas shift (RWGS) reaction is a crucial process in CO2 utilization. Herein, Ni- and NiCe-containing hexagonal mesoporous silica (Ni-HMS and NiCe-HMS) catalysts were synthesized using an in-situ one-pot method and applied for RWGS reaction. At certain reaction temperatures 500-750 ℃, Ni-HMS samples displayed a higher selectivity to the preferable CO than that of conventionally impregnated Ni/HMS catalyst. This could be originated from the smaller NiO nanoparticles over Ni-HMS catalyst. NiCe-HMS exhibited higher activity compared to Ni-HMS. The catalysts were characterized by means of TEM, XPS, XRD, H2-TPR, CO2-TPD, EPR and N2 adsorption-desortion technology. It was found that introduction of Ce created high concentration of oxygen vacancies, served as the active site for activating CO2. Also, this work analyzed the effect of the H2/CO2 molar ratio on the best NiCe-HMS. When reaction gas H2/CO2 molar ratio was 4 significantly decreased the selectivity to CO at low temperature, but triggered a higher CO2 conversion which is close to the equilibrium.
Electrochemical carbon dioxide reduction (CO2RR) plays an important role in solving the problem of high concentration of CO2 in the atmosphere and realizing carbon cycle. Core-shell structure has many unique features including tandem catalysis, lattice strain effect, defect engineering, which exhibit great potential in electrocatalysis. In this review, we focus on the advanced core-shell metal-based catalysts (CMCs) for electrochemical CO2RR. The recent progress of CMCs in electrocatalytic CO2RR is described as the following aspects: (1) The mechanism of electrochemical CO2RR and evaluation parameters of electrocatalyst performance, (2) preparation methods of core-shell metal catalysts and core-shell structural advantages and (3) advanced CMCs towards electrochemical CO2RR. Finally, we make a brief conclusion and propose the opportunities and challenges in the field of electrochemical CO2RR.
Improving the transfer hydrogenation of N-heteroarenes is of key importance for various industrial processes and remains a challenge so far. We reported here a microcapsule-pyrolysis strategy to quasi-continuous synthesis S, N co-doped carbon supported Co single atom catalysts (Co/SNC), which was used for transfer hydrogenation of quinoline with formic acid as the hydrogen donor. Given the unique geometric and electronic properties of the Co single atoms, the excellent catalytic activity, selectivity and stability were observed. Benefiting from the quasi-continuous synthesis method, the as-obtained catalysts provide a reference for the large-scale preparation of single atom catalysts without amplification effect. Highly catalytic performances and quasi-continuous preparation process, demonstrating a new and promising approach to rational design of atomically dispersed catalysts with maximum atomic efficiency in industrial.
Developing transition metal oxides (TMOs) with high energy, power, and long cycle lifetime for electric energy storage devices remains a critical challenge to date. Herein, we demonstrate a facile method that enables in-situ transformation of nickel cobalt oxide nanowire arrays (NiCoO NWA) into hierarchical nanowire-nanosheet arrays (ac-NiCoO NWSA) for enhanced energy storage properties. More specifically, the method leads to formation of atomically thin nanosheets (only 2.0 nm) and creates abundant antisite defects and oxygen vacancies. Owing to these merits, the as-prepared ac-NiCoO NWSA electrode exhibits over five-fold higher specific capacity, superior rate capability (up to 100 A/g), and excellent cycling stability of 10, 000 cycles at 50 A/g in alkaline electrolyte compared to pristine NiCoO NWA. Density functional theory (DFT) simulations elucidate the electrochemical activity enhancement mechanism of the TMOs. Moreover, our method triggers similar structural reconstruction phenomenon on other TMOs including ZnCo-, CoMn- and ZnNiCo-oxides, proving the universality of the method. Our findings provide a general method towards simultaneously manipulating the micro-morphologies and defects of TMOs for advanced energy storage devices.
Aqueous zinc anodes have attracted the attention of many researchers owing to their high safety, low cost, and high theoretical specific capacity. However, its practical application is severely limited by the dendrite growth on zinc anode. Herein, we develop an intrinsically zincophobic barium-titanate protective layer with a porous structure to suppress the zinc dendrite formation by homogenizing the ion distribution on the anode surface, increasing the nucleation sites, and limiting the irregular zinc growth. Based on these synergistic effects, the coated zinc anode can exhibit long cycle life (840 h at 0.5 mA/cm2 for 0.5 mAh/cm2) and low voltage hysteresis (36 mV). This work can provide a feasible direction for the design of intrinsically zincophobic coating materials to uniformize the zinc stripping and plating.
A new relay C–H functionalization of di([1, 1′-biphenyl]-2-yl)phosphine oxide to obtain esterified and hydroxylated products with different hypervalent iodines as oxidants under palladium catalysis is disclosed. This reaction provides a more effective and concise strategy for the synthesis of novel structural hybrid-arylcyclophosphorus ligand precursors with a wide range of substrates and good functional group tolerance.
Catalytic potential of carbon nanomaterials in peroxydisulfate (PDS) advanced oxidation systems for degradation of antibiotics remains poorly understood. This study revealed ordered mesoporous carbon (type CMK) acted as a superior catalyst for heterogeneous degradation of sulfadiazine (SDZ) in PDS system, with a first-order reaction kinetic constant (k) and total organic carbon (TOC) mineralization efficiency of 0.06 min-1 and 59.67% ± 3.4% within 60 min, respectively. CMK catalyzed PDS system exhibited high degradation efficiencies of five other sulfonamides and three other types of antibiotics, verifying the broad-degradation capacity of antibiotics. Under neutral pH conditions, the optimal catalytic parameters were an initial SDZ concentration of 44.0 mg/L, CMK dosage of 0.07 g/L, and PDS dosage of 5.44 mmol/L, respectively. X-ray photoelectron spectroscopy and Raman spectrum analysis confirmed that the defect structure at edge of CMK and oxygen-containing functional groups on surface of CMK were major active sites, contributing to the high catalytic activity. Free radical quenching analysis revealed that both SO4·- and ·OH were generated and participated in catalytic reaction. In addition, direct electron transfer by CMK to activate PDS also occurred, further promoting catalytic performance. Configuration of SDZ molecule was optimized using density functional theory, and the possible reaction sites in SDZ molecule were calculated using Fukui function. Combining ultra-high-performance liquid chromatography (UPLC)–mass spectrometry (MS)/MS analysis, three potential degradation pathways were proposed, including the direct removal of SO2 molecules, the 14S-17 N fracture, and the 19C-20 N and 19C-27 N cleavage of the SDZ molecule. The study demonstrated that ordered mesoporous carbon could work as a feasible catalytic material for PDS advanced oxidation during removal of antibiotics from wastewater.
The temperature of waste gas in refuse transfer station, airport smoking area, and RTO terminal is low, which needs deep oxidation. Catalytic ozonation is one of the most effective treatment techniques in these scenarios. In this study, we reported that catalysts were modified under the condition of magnetic field to simulate the low temperature dynamic conditions of low concentration toluene for catalytic ozonation. This paper aims to explore the relationship between oxygen vacancy and active oxygen species, and the specific pathways of toluene oxidation. The study found that citric acid can enhance the synergistic effect between Mn and Ce, and promote the generation of oxygen vacancies. The surface molecule adsorption oxygen is more conducive to catalytic oxidation than subsurface atom adsorption oxygen. Finally, we proposed the main pathways of toluene in this reaction system, which runs through the whole process of the reaction.
We herein proposed a sample introduction technique based on solution cathode glow discharge (SCGD) of a portable design for inductively coupled plasma-optical emission spectrometry (ICP-OES) and its application in sensitive determination of mercury. The products from SCGD containing mercury vapor, were transported by an Ar flow to ICP spectrometer for detection. A gas liquid separator (GLS) and a dryer were used to condense and remove most of the accompanying moisture, which greatly improved both the stability and sensitivity of the signal. The detection limit (DL) acquired by this developed method was 0.22 µg/L (194.1 nm), which was nearly 82 times lower than that obtained by pneumatic nebulization (PN). The relative standard deviation (RSD) was 1.4% (n = 14) for a 50 µg/L standard. Blank solution (HNO3, pH 1) can effectively elute mercury residue. Its accuracy and practicality were also demonstrated by the determination of GBW10029 (fish) certified reference material, shrimp, crawfish, soil and human hair samples. The results showed good consistency with the certified values and the values obtained using inductively coupled plasma−mass spectrometry.