This study aimed to isolate bacterial neuraminidase (BNA) inhibitory O-methylated quercetin derivatives from the aerial parts of S. pubescens. All the isolated compounds were identified as ...O-methylated quercetin (1–4), which were exhibited to be noncompetitive inhibitors against BNA, with ICsub.50 ranging from 14.0 to 84.1 μM. The responsible compounds (1–4) showed a significant correlation between BNA inhibitory effects and the number of O-methyl groups on quercetin; mono (1, ICsub.50 = 14.0 μM) > di (2 and 3, ICsub.50 = 24.3 and 25.8 μM) > tri (4, ICsub.50 = 84.1 μM). In addition, the binding affinities between BNA and inhibitors (1–4) were also examined by fluorescence quenching effect with the related constants (Ksub.SV, Ksub.A, and n). The most active inhibitor 1 possessed a Ksub.SV with 0.0252 × 10sup.5 L molsup.−1. Furthermore, the relative distribution of BNA inhibitory O-methylated quercetins (1–4) in S. pubescens extract was evaluated using LC-Q-TOF/MS analysis.
This work investigates the individual and combined effects of temperature and volatile organic compound precursor concentrations on the chemical composition of particles formed in the dark ozonolysis ...of α-pinene. All experiments were conducted in a 5 m.sup.3 Teflon chamber at an initial ozone concentration of 100 ppb and initial α-pinene concentrations of 10 and 50 ppb, respectively; at constant temperatures of 20, 0, or -15 .sup." C; and at changing temperatures (ramps) from -15 to 20 and from 20 to -15 .sup." C. The chemical composition of the particles was probed using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS).
This study aimed to enhance sludge dewatering through sequential bioleaching, employing the filamentous fungus Mucor sp. ZG-3 and the iron-oxidizing bacterium Acidithiobacillus ferrooxidans LX5. The ...mechanism by which Mucor sp. ZG-3 alleviates sludge dissolved organic matter (DOM) inhibition of A. ferrooxidans LX5 was investigated, and the optimal addition of energy source for enhanced sludge dewaterability during sequential bioleaching was determined. Sludge dissolved organic carbon (DOC) decreased to 272 mg/L with a 65.2% reduction by Mucor sp. ZG-3 in 3 days, and the degraded fraction of sludge DOM was mainly low-molecular-weight DOM (L-DOM) which inhibited the oxidization of Fe.sup.2+ by A. ferrooxidans LX5. By degrading significant inhibitory low-molecular-weight organic acids, Mucor sp. ZG-3 alleviated DOM inhibition of A. ferrooxidans LX5. In the sequential bioleaching process, the optimal concentration of FeSO.sub.4 ·7H.sub.2 O for A. ferrooxidans LX5 was 4 g/L, resulting in the minimum specific resistance to filtration (SRF) of 2.60x10.sup.11 m/kg, 40.0% lower than that in the conventional bioleaching process with 10 g/L energy source. Moreover, the sequential bioleaching process increased the sludge zeta potential (from -31.8 to -9.47 mV) and median particle size (d50) of the sludge particle (from 17.90 to 27.44 mum), contributing to enhanced sludge dewaterability. Inoculation of Mucor sp. ZG-3 during the bioleaching process reduced the demand for energy sources by A. ferrooxidans LX5 while improving sludge dewaterability performance.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The electrocatalysis of CO.sub.2 reduction to formic acid (HCOOH) as a useful chemical fuel has attracted much attention, but is facing the dilemma of low conversion efficiency. Herein, a series of ...transition elements were intentionally implanted into layered Bi.sub.2SeO.sub.2 surface to act as bimetallic reactive sites for decreasing the rate-limiting barriers. The calculations disclose that the doped 3d-metals can partially changes the electronic state distribution of 6 s lone pair electrons in Bi.sup.3+cation, in which this particular orbital hybridization leads to an intriguing bonding interaction between dopants and neighboring Se/O atomic layers. This interlayer electronic state coupling makes the half-filled dopants demonstrate the spin-resolved charge transfer and orbital interaction between bimetallic sites and reactants, because of the localized atomic distortion and electronic reconfiguration. This work provides a new insight into engineering surficial electronic structure and catalytic activity.
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•Caprock geological formations depict intermediate-wet conditions.•Increased pressure and reduced temperature inversely affect hydrogen wettability.•Hydrophilic caprock geological ...formations become intermediate wet in the presence of organic acids.
Actualization of the hydrogen (H2) economy and decarbonization goals can be achieved with feasible large-scale H2 geo-storage. Geological formations are heterogeneous, and their wetting characteristics play a crucial role in the presence of H2, which controls the pore-scale distribution of the fluids and sealing capacities of caprocks. Organic acids are readily available in geo-storage formations in minute quantities, but they highly tend to increase the hydrophobicity of storage formations. However, there is a paucity of data on the effects of organic acid concentrations and types on the H2-wettability of caprock-representative minerals and their attendant structural trapping capacities.
Geological formations contain organic acids in minute concentrations, with the alkyl chain length ranging from C4 to C26. To fully understand the wetting characteristics of H2 in a natural geological picture, we aged mica mineral surfaces as a representative of the caprock in varying concentrations of organic molecules (with varying numbers of carbon atoms, lignoceric acid C24, lauric acid C12, and hexanoic acid C6) for 7 days. To comprehend the wettability of the mica/H2/brine system, we employed a contact-angle procedure similar to that in natural geo-storage environments (25, 15, and 0.1 MPa and 323 K).
At the highest investigated pressure (25 MPa) and the highest concentration of lignoceric acid (10−2 mol/L), the mica surface became completely H2 wet with advancing (θa= 106.2°) and receding (θr=97.3°) contact angles. The order of increasing θa and θr with increasing organic acid contaminations is as follows: lignoceric acid > lauric acid > hexanoic acid. The results suggest that H2 gas leakage through the caprock is possible in the presence of organic acids at higher physio-thermal conditions. The influence of organic contamination inherent at realistic geo-storage conditions should be considered to avoid the overprediction of structural trapping capacities and H2 containment security.
The rising concentration of carbon dioxide (COsub.2) as one of the greenhouse gases in the atmosphere is a major source of worry. Electrochemical reduction of COsub.2 is one of many ways to convert ...COsub.2 gas into usable compounds. An electrochemical technique was applied in this study to reduce COsub.2 using a boron-doped diamond (BDD) working electrode modified with MXene (Tisub.3Csub.2Tsub.x) material to improve electrode performance. MXene concentrations of 0.5 mg/mL (MXene-BDD 0.5), 1.0 mg/mL (MXene-BDD 1.0), and 2.0 mg/mL (MXene-BDD 2.0) were drop-casted onto the BDD surface. MXene was effectively deposited on top of the BDD surface, with Ti weight loads of 0.12%, 4.06%, and 7.14% on MXene-BDD 0.5, MXene-BDD 1.0, and MXene-BDD 2.0, respectively. The modified working electrode was employed for COsub.2 electroreduction with optimal COsub.2 gas aeration. The existence of the MXene substance in BDD reduced the electroreduction overpotential of COsub.2. For the final result, we found that the MXene-BDD 2.0 electrode effectively generated the most formic acid product with a maximum reduction potential as low as −1.3 V (vs. Ag/AgCl).
During Fischer–Tropsch synthesis, O atoms are dissociated on the surface of Fe-based catalysts. However, most of the dissociated O would be removed as Hsub.2O or COsub.2, which results in a low atom ...economy. Hence, a comprehensive study of the O removal pathway as formic acid has been investigated using the combination of density functional theory (DFT) and kinetic Monte Carlo (kMC) to improve the economics of Fischer–Tropsch synthesis on Fe-based catalysts. The results show that the optimal pathway for the removal of dissociated O as formic acid is the OH pathway, of which the effective barrier energy (0.936 eV) is close to that of the CO activation pathway (0.730 eV), meaning that the removal of dissociated O as formic acid is possible. The main factor in an inability to form formic acid is the competition between the formic acid formation pathway and other oxygenated compound formation pathways (Hsub.2O, COsub.2, methanol-formaldehyde); the details are as follows: 1. If the CO is hydrogenated first, then the subsequent reaction would be impossible due to its high effective Gibbs barrier energy. 2. If CO reacts first with O to become COsub.2, it is difficult for it to be hydrogenated further to become HCOOH because of the low adsorption energy of COsub.2. 3. When the CO + OH pathway is considered, OH would react easily with H atoms to form Hsub.2O due to the hydrogen coverage effect. Finally, the removal of dissociated O to formic acid is proposed via improving the catalyst to increase the COsub.2 adsorption energy or CO coverage.
Keywords Host-guest cage structured; MNPs@ALG@SiO.sub.2 composite; Embedding immobilized enzyme; Degradation of TeCG Highlights * Cage structure of MNPs @ ALG@SiO.sub.2 as enzyme carrier was ...synthesized. * The synthetic cage structure has high performance for the degradation of tetrachloroguaiacol. * Optimized the conditions for the degradation of tetrachloroguaiacol by magnetic composite cage structure. * The degradation mechanism were studied in detail. Entrapment of enzyme in a cage structure of alginate/silica composite gel can maintain the chemical or configurational structures unchanged in the enzyme, providing a promising means of enzyme immobilization. The alginate/silica composite gel can also provide more adsorption sites for the substrate, which is biocompatible and will carry out degradation and adsorption of pollutants within a cage-like structure reactor simultaneously. In this study, we used a magnetic host-guest cage structured MNPs@ALG@SiO.sub.2 composite with a specific enzyme embedded as its guest in the host matrix, to enhance its performance. Additionally, its swelling, leakage rate and immobilization conditions were optimized. The magnetic nanoparticles (MNPs) were used to compensate for the ease of collapse of the internal structure of alginic acid, while SiO.sub.2 was used to enhance the swelling resistance of the carrier and prevent the degradation of polysaccharides in the natural environment, thereby maintaining the enzyme biological activity and immobilization rate. Finally, the effects on the degradation of tetrachloroguaiacol (TeCG) by the immobilized enzyme embedded in the MNPs@ALG@SiO.sub.2 composite were investigated. When the concentration of ALG was 2% and the TEOS concentration was 40 %, the immobilized MNPs@ALG@SiO.sub.2 was found to perform the best. The optimum conditions of immobilizing laccase are pH = 5, enzyme concentration 0.4 g/L, adsorption time 12 h and temperature 20 a. The degradation conditions of TeCG are pH = 6, degradation temperature 40 a, degradation time 10 h and the degradation products of TeCG were acetic acid and ethanol according to GC--MS. Author Affiliation: (a) School of Chemistry and Molecular Engineering, East China University of Science & Technology, Shanghai, 200237, China (b) State Key Laboratory of Geohazard Prevention and Geoenvironment Protection (Chengdu University of Technology), Chengdu, 610059, China (c) Department of Materials Science and Engineering, University of Delaware, DE, 19716, USA (d) State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Changchun, 130012, China * Corresponding author at: School of Chemistry and Molecular Engineering, East China University of Science & Technology, Shanghai, 200237, China. Article History: Received 3 September 2020; Revised 9 December 2020; Accepted 30 December 2020 Byline: Jie Li (a), Yuxiang Yang yxyang@ecust.edu.cn (a,c), Zhiyong Han (b), Min Zhao (a), Hongming Yuan (d), Chaoying Ni cni@udel.edu (c)
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