Search

Very recently, open-cage metallo-azafullerenes PbC100N4H4 and Pb2C100N4H4 containing one Pb–N4–C moiety have been synthesized via the electron beam. Herein, we utilized density functional theory calculations in combination with ab initio molecular dynamics (AIMD) simulations to study the geometric and electronic structures, bonding properties, thermodynamic stability, and catalytic performance of MC100N4H4 and M2C100N4H4 (M = Ge, Sn, Pb). Metal–nitrogen distances and metal–metal distances increase along with the metal radius while the metal atom is positively charged. Energy decomposition analysis revealed that the bonding interactions between M and the C100N4H4 fragment could be described as the donor–acceptor interaction between M(ns0(n−1)d10np4) and C100N4H4 fragment, in which the orbital interactions terms contribute more than the electrostatic interactions. AIMD simulations demonstrate that those metallo-azafullerenes exhibit thermodynamic stability at room temperature. These metallo-azafullerenes, which could serve as typical carbon-supported single-atom catalysts, possess enhanced catalytic performance toward the oxygen reduction reaction (ORR) compared to the planar catalysts, which is attributed to the curvature of metallo-azafullerenes. GeC100N4H4 and SnC100N4H4 exhibit high catalytic performance in the 4e-ORR pathway to H2O, whereas only PbC100N4H4 is suitable for the 2e-ORR reaction pathway because of the difficulty in obtaining electrons. All M2C100N4H4 favors the 4e-reaction pathway due to the presence of the axial metal atom. Our finding of open-cage metallo-azafullerenes as efficient single-atom catalysts holds profound implications for both fundamental research in catalysis and practical applications in fuel cells and other electrochemical devices. [ABSTRACT FROM AUTHOR]

Developing an OER electrocatalyst that balances high performance with low cost is crucial for widely adopting PEM water electrolyzers. Ru-based catalysts are gaining attention for their cost-effectiveness and high activity, positioning them as promising alternatives to Ir-based catalysts. However, Ru-based catalysts can be prone to oxidation at high potentials, compromising their durability. In this study, we utilize a simple synthesis method to synthesize a SnO2, Nb2O5, and RuO2 composite catalyst (SnO2/Nb2O5@RuO2) with multiple interfaces and abundant oxygen vacancies. The large surface area and numerous active sites of the SnO2/Nb2O5@RuO2 catalyst lead to outstanding acidic oxygen evolution reaction (OER) performance, achieving current densities of 10, 50, and 200 mA cm−2 at ultralow overpotentials of 287, 359, and 534 mV, respectively, significantly surpassing commercial IrO2. Moreover, incorporating Nb2O5 into the SnO2/Nb2O5@RuO2 alters the electronic structure at the interfaces and generates a high density of oxygen vacancies, markedly enhancing durability. Consequently, the membrane electrode composed of SnO2/Nb2O5@RuO2 and commercial Pt/C demonstrated stable operation in the PEM cell for 25 days at an industrial current density of 1 A cm−2. This research presents a convenient approach for developing a highly efficient and durable Ru-based electrocatalyst, underscoring its potential for proton exchange membrane water electrolysis. [ABSTRACT FROM AUTHOR]

Heterogeneous catalysts promoting efficient production of reactive species and dynamically stabilized electron transfer mechanisms for peroxomonosulfates (PMS) still lack systematic investigation. Herein, a more stable magnetic layered double oxides (CFLDO/N‐C), was designed using self‐polymerization and high temperature carbonization of dopamine. The CFLDO/N‐C/PMS system effectively activated PMS to remove 99% (k = 0.737 min−1) of tetracycline (TC) within 10 min. The CFLDO/N‐C/PMS system exhibited favorable resistance to inorganic anions and natural organics, as well as satisfactory suitability for multiple pollutants. The magnetic properties of the catalyst facilitated the separation of catalysts from the liquid phase, resulting in excellent reproducibility and effectively reducing the leaching of metal ions. An electronic bridge was constructed between cobalt (the active platform of the catalyst) and PMS, inducing PMS to break the O–O bond to generate the active species. The combination of static analysis and dynamic evolution confirmed the effective adsorption of PMS on the catalyst surface as well as the strong radical‐assisted electron transfer process. Eventually, we further identified the sites where the reactive species attacked the TC and evaluated the toxicity of the intermediates. These findings offer innovative insights into the rapid degradation of pollutants achieved by transition metals in SR‐AOPs and its mechanistic elaboration. [ABSTRACT FROM AUTHOR]

The purpose of the current study was to characterize role of microRNA (miR)-519d in trophoblast cells and preeclampsia (PE) development and its potential underlying mechanism. Regulation of leptin (LEP) by miR-519d was verified using a dual-luciferase reporter gene assay. Loss- and gain-of-function assays were conducted to detect the roles of miR-519d and LEP in proliferation, migratory ability, and invasive capacity of HTR-8/SVneo cells by means of CCK-8 assay, scratch test, and Transwell invasion assay, respectively. The cell apoptosis rate and cycle distribution were analyzed by flow cytometry. LEP expression was elevated, whereas miR-519d level was suppressed in the PE placenta samples compared with those from normal pregnancy. Depletion of LEP promoted proliferation, migratory ability, and invasive capacity and repressed apoptosis. miR-519d could bind 3′ untranslated regions (3′UTRs) of LEP, the extent of which correlated negatively with LEP expression. miR-519d suppressed the expression of LEP in HTR-8/SVneo cells. Moreover, overexpression of miR-519d promoted survival and migratory ability of HTR-8/SVneo cells. Taken together, we find that miR-519d targeted LEP and downregulated its expression, which could likely inhibit the development of PE.

Simultaneously improving activity and stability is a crucial yet challenge in the development of metallic single‐atom‐based catalysts. In current work, a novel approach is introduced to address this issue by combining post‐adsorption and secondary pyrolysis techniques to create a synergistic catalytic system, in which the single atoms (SAs) Fe sites played in the NC matrix (Fe─NC) are coupled with high‐entropy atomic clusters (HEACs). Theoretical calculations reveal that the incorporation of HEACs lead to a rehybridization of the 3d orbital configuration of Fe‐N4, which helps to balance the adsorption/desorption energy of oxygenated intermediates. In situ spectroscopy further reveals that the rate‐limiting step of OH* desorption on HEAC/Fe─NC in oxygen reduction reaction (ORR) is more facile compared to atomic Fe─NC, implying a higher ORR activity. Moreover, the synergistic effect of diffusion activation barriers and configuration entropy contributes to the structural stability of HEAC/Fe─NC, resulting in remarkable durability. Consequently, this unique catalyst exhibits half‐wave potentials of 0.927 and 0.828 V in an aqueous solution of KOH (0.1 m) and HClO4 (0.1 m), respectively, along with excellent durability. The findings propose a novel strategy for modulating the electronic structure of metallic SAs catalysts and enhancing their stability through strong interactions between SAs and HEACs. [ABSTRACT FROM AUTHOR]

It is of great importance to promote charge separation in photocatalysts for enhanced photocatalytic activity under visible light irradiation. In this work, a type-II heterostructured photocatalyst was constructed by compositing phosphorus-doped g-C3N4 (P-CN) and Rh-doped SrTiO3 (Rh-STO) via a thermal calcination treatment. A series of characterizations were conducted to investigate the structure of heterostructured P-CN/Rh-STO. It was found that Rh-STO interacted with in situ generated P atoms from the decomposition of P-CN during the calcination process, thus leading to the formation of heterojunction of P-CN/Rh-STO. Compared with the single component, i.e., P-CN or Rh-STO, the obtained P-CN/Rh-STO showed superior photocatalytic activity to that of both P-CN and Rh-STO due to the effective charge separation across the heterojunction between P-CN and Rh-STO. [ABSTRACT FROM AUTHOR]

The photocatalytic performances are highly dependent on the charge separation and surface reaction kinetics of photocatalysts. Aiming at figuring out the effects of co-catalyst with the lower Fermi level on photocatalytic activity, we tuned the Fermi level of Pt nanoparticles on g-C3N4(GCN) by introducing Co atom. Experimental results show that lowering the Fermi level of co-catalyst does not alter light absorption of GCN due to the invariable structure. Besides, Pt3Co with a lower Fermi level contributes less positive influence on charge separation in GCN due to an opposite effect from the stronger electron-trap ability of Pt3Co and increased band bending in GCN-Pt3Co. The density functional theory (DFT) calculations indicate that GCN-Pt3Co has faster surface reaction kinetics than GCN-Pt, owing to easier dissociation of H2O molecules and faster desorption of H* on Pt3Co. Consequently, GCN-Pt3Co exhibits an excellent H2 evolution rate with 2.91 mmol·g−1·h−1, which 2.67 times that of GCN-Pt. [ABSTRACT FROM AUTHOR]

Although Ruthenium-based pyrochlore oxides can function as promising catalysts for acidic water oxidation, their limitations in terms of stability and activity still need to be addressed for further application in practical conditions. In this work, the possibility to enhance both oxygen evolution reaction activity and durability of Gd 2 Ru 2 O 7- δ through partial replacement with Na + in Gd 3+ sites is first offered, leading to the electronic and geometric regulation of active center RuO 6 . Na + triggers the emergence of Ru <4+ and the electron rearrangement of active-centered RuO 6 . Specifically, Ru ions with a negative d-band center after Na + doping exhibit weaker adsorption energies of *O and result in the conversion of the rate-limiting step from *O/*OOH to *OH/O*, reducing energy barriers for boosting activities. Therefore, the Na x Gd 2- x Ru 2 O 7- δ requires a low overpotential of 260 mV at 10 mA cm -2 in 0.1 m HClO 4 electrolyte. Moreover, the higher formation energy of Ru vacancy and less distorted RuO6 enable the as-prepared Na x Gd 2- x Ru 2 O 7- δ to operate steadily at 10 mA cm -2 for 300 h and multi-current chronopotentiometry with current densities from 20 to 100 mA cm -2 for 60 h in acidic proton exchange membrane electrolyzer, respectively., (© 2023 Wiley‐VCH GmbH.)

Objectives: To investigate influencing factors of intrapartum fever during vaginal delivery and to construct a prediction model for infectious intrapartum fever., Methods: A total of 444 patients with intrapartum fever admitted in Ningbo Women and Children's Hospital from January 2020 to December 2021 were enrolled. The clinical data and laboratory findings were compared between patients with infectious intrapartum fever and non-infectious intrapartum fever, and the factors associated with intrapartum fever were analyzed with a multivariate logistic regression model. A prediction nomogram model was constructed based on the factors of intrapartum fever and its predictive efficiency was evaluated by correction curve and receiver operator characteristic curve., Results: In the 444 cases, 182 (41.0%) had definite intrauterine infection and 262 (59.0%) had no infectious intrapartum fever. Univariate analysis showed that the length of hospital stay before induced labor, the time of induced abortion, misoprostol administration, autoimmune diseases, white blood cell count (WBC) and hypersensitive C-reactive protein (hs-CRP) levels were significantly different between the two groups (all P <0.05). Multivariate analysis showed that misoprostol administration and autoimmune diseases were protective factors ( OR =0.31 and 0.36, both P <0.05) for infectious intrapartum fever, while high WBC and hs-CRP were risk factors ( OR =1.20 and 1.09, both P <0.05). The area under the curve of nomogram model for predicting infectious intrapartum fever was 0.823, and the calibration curve validation showed that the predicted and measured values were in general agreement., Conclusions: Multiple factors cause intrapartum fever. The nomogram model constructed in this study has good predictive accuracy for infectious intrapartum fever.