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Low-coordinated single atom catalysts compared to M-N4 are appealing in optimized electronic structure for CO2 electro-reduction, but the preparation is still very challenging. Herein, a novel single Ni atom catalyst with Ni-N1-C3 configuration is in-situ evolved on curved carbon nanotubes. The obtained Ni-N1-C3 catalyst exhibits a superior CO Faradaic efficiency of 97% and turnover frequency of 2,890 h−1 at −0.9 V versus the reversible hydrogen electrode, as well as long-term stability over 45 h. High current densities exceeding 200 mA·cm−2 and CO Faradaic efficiency of 99% are achieved in flow-cell. Moreover, in-situ potential-and time-dependent Raman spectra identify the key intermediates of *COOH and *CO during CO2-to-CO conversion. Theoretical calculations reveal that the upward-shifted d-band center and charge-rich Ni sites of Ni-N1-C3 facilitate the electron transfer to *COOH and thus reduce the *COOH formation energy barrier. This work demonstrates a strategy for modulating the coordination environment for efficient CO2 reduction. [ABSTRACT FROM AUTHOR]

The separation of C2H2/CO2 is not only industrially important for acetylene purification but also scientifically challenging owing to their high similarities in physical properties and molecular sizes. Ultramicroporous metal-organic frameworks (MOFs) can exhibit a pore confinement effect to differentiate gas molecules of similar size. Herein, we report the fine-tuning of pore sizes in sub-nanometer scale on a series of isoreticular MOFs that can realize highly efficient C2H2/CO2 separation. The subtle structural differences lead to remarkable adsorption performances enhancement. Among four MOF analogs, by integrating appropriate pore size and specific binding sites, [Cu(dps)2(SiF6)] (SIFSIX-dps-Cu, SIFSIX = SiF62-, dps = 4.4'-dipyridylsulfide, also termed as NCU-100) exhibits the highest C2H2 uptake capacity and C2H2/CO2 selectivity. At room temperature, the pore space of SIFSIX-dps-Cu significantly inhibits CO2 molecules but takes up a large amount of C2H2 (4.57 mmol g−1), resulting in a high IAST selectivity of 1787 for C2H2/CO2 separation. The multiple host-guest interactions for C2H2 in both inter- and intralayer cavities are further revealed by dispersion-corrected density functional theory and grand canonical Monte Carlo simulations. Dynamic breakthrough experiments show a clean C2H2/CO2 separation with a high C2H2 working capacity of 2.48 mmol g−1. The separation of acetylene and carbon dioxide by porous materials requires delicate control over the pore size. Herein, the authors fine-tune the pore size at sub-nanometer scale in a series of isoreticular metal-organic frameworks to control the acetylene/carbon dioxide separation performance; subtle structural differences lead to remarkable performance enhancement. [ABSTRACT FROM AUTHOR]

Efficient adsorptive separation of acetylene (C2H2) from carbon dioxide (CO2) or ethylene (C2H4) is industrially important but challenging due to the identical dynamic diameter or the trace amount. Here we show an electrostatic potential compatible strategy in a nitroprusside-based Hofmann-type metal-organic framework, Cu(bpy)NP (NP = nitroprusside, bpy = 4,4'-bipyridine), for efficient C2H2 separation. The intruding cyanide and nitrosyl groups in undulating one-dimensional channels induce negative electrostatic potentials for preferential C2H2 recognition instead of open metal sites in traditional Hofmann-type MOFs. As a result, Cu(bpy)NP exhibits a 50/50 C2H2/CO2 selectivity of 47.2, outperforming most rigid MOFs. The dynamic breakthrough experiment demonstrates a 99.9% purity C2H4 productivity of 20.57 mmol g−1 from C2H2/C2H4 (1/99, v/v) gas-mixture. Meanwhile, C2H2 can also be captured and recognized from ternary C2H2/CO2/C2H4 (25/25/50, v/v/v) gas-mixture. Furthermore, computational studies and in-situ infrared spectroscopy reveal that the selective C2H2 binding arises from the compatible pore electro-environment generated by the electron-rich N and O atoms from nitroprusside anions. Separating acetylene from carbon dioxide or ethylene is challenging due to near identical molecular diameters or the trace amounts. Here authors prepare nitroprusside-based Hofmann-type MOFs for efficient C2H2 separation and recognition. [ABSTRACT FROM AUTHOR]

Facilely tailored electrocatalyst with high-efficiency and durability for carbon dioxide (CO2) to carbon monoxide (CO) conversion is appealing but remains challenging. Herein, small nickel nanoparticles (about 19.4 nm) confined in nitrogen-doped carbon (Ni NPs@N–C) with narrow size distribution are successfully constructed via a facile one-step calcination strategy of Ni containing MOF compounds. By virtue of the protective N-doped graphitized carbon shell and the uniformly distributed fine Ni nanoparticles in a narrow range from 13 to 21 nm, the as-obtained Ni NPs@N–C can exclusively convert CO2 into CO with excellent Faradaic efficiency (FE) of 96.8% at − 1.0 V (vs. RHE), as well as the superior long-term catalytic stability over 24 h. Moreover, a high current density of more than 200 mA cm−2 with a stable CO FE of 92% can be achieved in a flow cell configuration. This work paves a new way for the facile and potentially scale preparation of small metal nanoparticles for efficient CO2- to-CO conversion. [ABSTRACT FROM AUTHOR]

The study aimed to investigate the bioaccessibility and the stability of purified ethanol extracts (PEE) from Cudrania cochinchinensis roots, and the changes in antioxidant activity and enzyme inhibition activity and cytotoxicity by in vitro digestion. No compounds were lost during the gastrointestinal digestion (GID) process, 15 compounds were tentatively identified using UPLC-TOF-MS/MS technology, including five phenolic and ten flavonoid compounds. After the gastric digestion (GD), the bioaccessibility of phenolic and flavonoid compounds was 55.66% and 52.44%, respectively. After the intestinal digestion (ID), the bioaccessibility of phenolic and flavonoid compounds reduced to 39.70% and 33.36%, respectively. The gastrointestinal digestion (GID) decreased the bioaccessibility of phenolic compounds. All compounds were affected throughout the gastrointestinal digestion (GID), among which the more affected compounds were 4-hydroxybenzoic acid, eriodictyol-7-O-glucoside, resveratrol and 3,6,3',4'-tetrahydroxyflavone (compared with the peak intensity of the undigested PEE). Furthermore, there was a reduction in the antioxidant activity, inhibition activity against α-glucosidase and tyrosinase, and cytotoxicity toward HepG2 cells of the PEE after GID. There was a significantly positive correlation between the bioactivity and the total phenolic/flavonoid contents. The results showed that in vitro digestion had significant effects on the phenolic content and bioactivity. Although phenolic contents were decreased during GID, C. cochinchinensis roots is still a good source of bioactive compounds for the development of functional foods with health benefits. [ABSTRACT FROM AUTHOR]

The low electron conductivity and scarce electrochemically active sites impede the practical application of bimetal oxides for supercapacitors. Herein, fluorine-doped and oxygen vacancy–enrich NiMoO4 (F-NiMoO4-x) nanosheet arrays are constructed via facile hydrothermal and wet chemical reduction processes on carbon cloth fibers (CFC). The structural and electronic properties in F-NiMoO4-x can be modulated by the synergistic effect of dopant F and O vacancies to boost the electrical conductivity and enhance Faradaic redox sites. The obtained flexible F-NiMoO4-x@CFC as a self-supporting electrode can provide superior areal capacitance of 2.45 F cm−2 at 1 mA cm−2, 6-fold higher than that of pristine NiMoO4@CFC electrode. Moreover, the assembled flexible solid-state asymmetric supercapacitor (ASC) delivers an impressive energy density of 336.5 μWh cm−2 at a power density of 1790 μW cm−2 with a wide voltage window of 1.8 V. Moreover, the ASC can work at different bending angels with an ultralong and stable lifespan. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the antioxidant and enzyme inhibitory activity, and characterize the bioactive constituents of the phenolic extract of Potentilla discolor Bge. Dry material of Potentilla discolor Bge. was extracted with 80% ethanol solution to obtain the crude phenolic extract (CPE) with the total phenolic content (TPC) of 20.40 ± 0.69 mg of gallic acid equivalents per gram of dry material (mg GAE/g DM). After purified with AB-8 macroporous resin, TPC of the purified phenolic extract (PPE) (353.65 ± 5.50 mg GAE/g DM) was much higher than that of the CPE. PPE exhibited stronger 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and 2,2′-azino-bis 3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging activity than CPE and 2,6-Di-tert-butyl-4-methylphenol (BHT), with the IC50 values of 0.030 ± 0.002 mg/mL and 0.059 ± 0.002 mg/mL, respectively. The total antioxidant activities of PPE and BHT were similar, and were higher than CPE. PPE was found to significantly inhibit α-amylase and α-glucosidase with IC50 values of 0.966 ± 0.072 and 2.431 ± 0.088 mg/mL, respectively. Finally, using UPLC-TOF–MS/MS technology, 35 compounds were tentatively identified, including 12 phenolic acids, 23 flavonoids and their derivatives, 29 of which have been discovered for the first time in Potentilla discolor Bge. These results suggested that PPE had the potential to be used as an antioxidant and anti-diabetic component in functional foods. [ABSTRACT FROM AUTHOR]

Developing highly efficient heterogeneous catalysts for cycloaddition of CO2 and epoxides to produce cyclic carbonates is promising but challenging. In this work, a novel three-dimensional metal organic framework (MOF) with cylinder pore systems and unsaturated Zn sites has been demonstrated as potent candidate in CO2 fixation at mild and solvent-free conditions. The Zn(atz)(bdc)0.5, where atz = aminotriazole and H2bdc = terephthalic, exhibits microporous nature that can regulate the catalytic interaction of active centers and substrates. The structure stability has been systematically investigated and proven to be sufficient for practical application. Furthermore, the cooperative effects of porosity, CO2 binding affinity, activation centers, and synergism with co-catalyst have been deeply investigated. Moreover, high propylene epoxide conversion (97%) and selectivity (> 99%) have been achieved at mild conditions (60 °C and 1 MPa) with excellent cycle stability. Owing to the well-defined pore system, an obvious substrates selectivity has been clearly observed. A possible catalytic mechanism has been proposed and verified by DFT calculations. Furthermore, the prepared Zn-MOF can also be used as an efficient heterogeneous catalyst for the reaction of epoxides with alcohols to produce β-alkoxy alcohol. [ABSTRACT FROM AUTHOR]

The composites consisting of nitrogen-doped carbon nanotubes (N-CNTs) and nitrogen-doped carbon nanofibers (N-CNFs) were fabricated using a mixture of nickel foam (template) and imidazole (solid precursor) in a facile one-step chemical vapor deposition (CVD) process. The morphology and microstructure of the N-doped carbon nanotubes/N-doped carbon nanofibers hierarchical composites (N-CNTs/N-CNFs) were determined by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectra, and X-ray photoelectron spectroscopy. The results indicated that the sample manifests regular hierarchical composites, great graphitization, and nitrogen doping. Furthermore, a probable growth mechanism is presented to analyze the composites. [ABSTRACT FROM AUTHOR]

We report here the one-step water-assisted CVD growth of metal oxide nanosheets/carbon nanotubes (CNTs) composites. The cross-linked composites were characterized by scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. The results showed that helical CNTs were obtained when the CVD growth process was prolonged to 1 h, and the typical fish-bone-type CNTs can be observed by HRTEM. Moreover, a related growth mechanism is proposed to explain the growth of such novel nanocomposites. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to increase the proteinase activity of the strain NCU116 by combining ultraviolet irradiation and N-methyl- N′-nitro- N-nitroso guanidine treatment, in order to enhance the efficiency of Cinnamomum camphora seed kernel oil (CCSKO) extraction by aqueous enzymatic method (AEM). The mutated strain, designated as NCU116-1, was screened out by the ratio of hydrolytic zone diameter to colony diameter on skim milk plate. The proteinase activity (9116.1 U/ml) of NCU116-1 was increased by 31.9% compared with the parental strain. The extracellular enzymes produced by NCU116-1 included proteinase, pectase, glucoamylase, cellulase and amylase. The proteinase had the maximum activity at 50 °C. Its optimum temperature and pH value were approximately 45 °C and 8.0 respectively. Mn was an activator of neutral proteinase. The glucoamylase had the maximum activity at 35 °C, and was activated by Cu, Fe and Mn. Its optimum temperatures and pH value were 35 °C and 8.0 respectively. The pectinase had the maximum activity at 40 °C, and was activated by Ca and Mn. Its optimum temperatures and pH value were 35-40 °C and 6.0 respectively. The optimum conditions of CCSKO extraction by AEM were also investigated. The results suggested that the best amount of enzyme solution and enzymolysis time were 20% (v/v) and 4 h, respectively. The oil extraction rate was 95.2% under these conditions. Thus, a suitable mutated strain was selected for CCSKO extraction by AEM and the optimum extraction conditions were determined. [ABSTRACT FROM AUTHOR]

Ligupurpuroside A is a glycoside extracted from Ku-Ding tea. As extracts from Ku-Ding tea exhibit anti-inflammatory property, we hypothesize that Ligupurpuroside A may be an active compound which inhibits trypsin activity during the anti-inflammatory process. The mechanism and nature of inhibition of trypsin by Ligupurpuroside A have been studied by multi-spectroscopic method, enzyme-activity assay and molecular docking. Enzyme activity assay reveals that Ligupurpuroside A significantly inhibits the activity of trypsin through a competitive manner with an IC value of 3.08 × 10 mol L. Fluorescence titration together with thermodynamic analysis indicate that a Ligupurpuroside A-trypsin complex is formed, and that hydrophobic force and hydrogen bonding are the main forces stabilizing the complex. UV-vis absorption, synchronous fluorescence and circular dichroism spectra show that the interaction between Ligupurpuroside A and trypsin induces conformational changes of trypsin with a decrease in the contents of α-helix and β-sheet. Finally, molecular docking further suggests that Ligupurpuroside A molecule binds within the active pocket of trypsin via hydrophobic force and hydrogen bond. Results from this study of the interaction of trypsin with its natural inhibitor should be useful to minimize the antinutritional effects and make full use of tea extracts in the food industry, and be also helpful to the design of the drugs for the diseases related to overexpression of trypsin. [ABSTRACT FROM AUTHOR]