Latest ArticlesThe structure-activity relationships for vinyl acetate catalytic oxidation are challenging to explore at the atomic scale due to the ambiguity of the structural defect types and sites of manganese oxides. Our work elaborates, at the atomic level, through in-situ experimental and theoretical methods, the synergistic effects of two types of structural defect sites of VO-e (edge-sharing oxygen) and VO-c (corner-sharing oxygen) and MnO6 structural motifs of manganese oxides. Multi-dimensional manganese oxides, namely those with corner-connected MnO6 structural motifs and VO-c structural oxygen defect sites, significantly improved the activation of vinyl acetate. Enhancement of enol structure formation, acetate and formate intermediate species, and tautomerism between enol structure and acetaldehyde were detected when oxygen vacancies of manganese oxides were present in combination with corner/edge-connected MnO6. Moreover, the activation of chemical bonds and deep catalytic oxidation of vinyl acetate depend on the presence of a redox couple, surface oxygen species, and weakened MnO bonds. It provides a valuable notion for investigating and designing catalytic systems and reaction processes for the purpose of emission reduction and the management of environmental contaminants.
Drug-resistant bacteria present a severe threat to public health, emphasizing the importance of developing broad-spectrum antibacterial agents that are free from drug resistance. Among silver-based antibacterial agents, nano-silver has been found to exhibit the most promising and comprehensive performance. The exploration of the antibacterial capacity and morphological changes of silver nanoparticles (AgNPs) could offer a starting point for the development of safe and efficient antibacterial agents. In this study, three types of nano-silver-modified polyphosphazene (PRV) nanoparticles with different morphologies were synthesized using precipitation polymerization. These nanoparticles were characterized using various techniques, including Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The antibacterial activity of these nanoparticles against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was assessed using minimum inhibitory concentration (MIC)/minimum bactericidal concentration (MBC) tests and inverted fluorescence microscopy. Our results revealed that the antibacterial activity of silver nanoparticles can vary significantly depending on their immobilized form. Ag@PRV Strawberry-like nanoparticles (NPs) exhibited higher antibacterial activity compared to Ag@PRV Yolk-Shell NPs and Ag@PRV Cable-like nanofibers (NFs). Notably, all three types of synthesized nanoparticles demonstrated a stronger bactericidal effect on Gram-positive bacteria than Gram-negative bacteria. Live/dead bacterial staining and scanning electron microscopy demonstrated that silver can kill bacteria by altering the permeability of their cell membranes. These findings offer valuable insights for designing and practically applying new silver-based antibacterial agents in the future.
To solve the problem of energy scarcity and widespread environmental contamination, it is necessary to design green and low-cost photocatalysts for water splitting. In this paper, a new penta-graphene/AlAs5 (PG/AlAs5) van der Waals (vdW) heterostructure is proposed and its performance for photocatalytic hydrolysis is calculated using the first-principles method. The findings suggest that the PG/AlAs5 heterostructure belong to type-Ⅱ indirect semiconductor, and the edge position and band gap width of this heterostructure satisfy the requests of redox reaction. Furthermore, the oxidation reaction (OER) on the AlAs5 side and the hydrogen evolution reaction (HER) on the PG side are thermodynamically spontaneous under different conditions. Surprisingly, the introduction of strain engineering has changed the position of the band edge and light absorption performance of PG/AlAs5 heterostructure, which is powerful for the performance of photocatalytic water splitting. The PG/AlAs5 vdW heterostructure exhibits well visible light absorption intensity without applying strain and biaxial strain of 2%. In conclusion, the findings suggest that the PG/AlAs5 vdW heterostructure is a prospecting catalyst for visible-light hydrolysis.
“Rocking chair” type lithium-ion batteries with lithium metal-free anodes have been successfully commercialized over the past few decades. Zinc-ion batteries (ZIBs) have gained increasing attention in recent years given their safety, greenness, ease of manufacture, and cost-efficiency. Nevertheless, the practical application of ZIBs is largely hindered by the dendritic growth of the Zn metal anode, low Coulombic efficiency, great harm, and existence of various side reactions. Herein, this review provides a systematic overview of emerging “rocking chair” type ZIBs with zinc metal-free anodes. Firstly, the basic fundamentals, advantages, and challenges of “rocking chair” type ZIBs are introduced. Subsequently, an overview of the design principles and recent progress of “rocking chair” type ZIBs with zinc metal-free anodes are presented. Finally, the key challenges and perspectives for future advancement of “rocking chair” type ZIBs with zinc metal-free anodes are proposed. This review is anticipated to attracted increased focus to metal-free anodes “rocking chair” type metal-ion battery and provide new inspirations for the development of high-energy metal-ion batteries.
The currently reported axial chiral molecules based on the 3,3′-substitution of the binaphthyl skeleton are limited by intrinsic fluorescence properties, resulting in generally low device efficiencies (EQE < 5%) of related organic light emitting diodes (OLEDs). Herein, we designed and synthesized four pair of chiral binaphthyl enantiomers (R/S-1 − R/S-4) adopting acceptor-donor-donor-acceptor (ADDA) structure by introducing different thioxanthone modification groups on the 3,3′-position of 2,2′-dimethoxy-1,1′-binaphthalene. Among them, emitter R/S-2 and R/S-4 obtained by enhancing intramolecular charge transfer exhibited TADF characteristics due to relatively small ΔEST of 0.12 eV and 0.17 eV, and relatively moderate SOC matrix elements of 0.28 cm−1 and 0.10 cm−1 between the 1CT and 3LE states. The CD spectra of these enantiomers in diluted solutions showed perfect mirror images and reasonable gabs for small organic molecules (10−4–10−3). And the external quantum efficiencies (EQE) of 10.9% and 8.32% for device A and B based on emitter S-2 and S-4 were highest compared with currently reported axial chiral molecules based on the 3,3′-position substitution of binaphthyl skeleton, providing simple molecular design strategies to construct efficient CP-OLED device.
A wavelength-dependent three-dimensional (3D) superlocalization imaging method on gold nanoislands (GNIs) chip was developed as a supersensitive single-molecule thyroid-stimulating hormone (TSH) nanobiosensor. Scattered and fluorescent signals from gold nanoislands on the substrate and quantum dots (QDs) nanoprobes were simultaneously isolated and acquired within an evanescent field layer generated by total internal reflection (TIR) of incident light using a dual-view device. The 3D TIR fluorescence images of TSH-bound QDs on the GNIs were obtained using z-axis optical sectioning at 10 nm intervals before/after immunoreaction to identify the optimal conditions for detection. The localized centroid position of QD nanoprobes and GNI were distinguished at a subdiffraction limit resolution using 3D Gaussian fitting to the point spread function. The QD TSH nanobiosensor using wavelength-dependent 3D TIR fluorescence-based single-molecule localization microscopy (3D TIRF-SLM) imaging technique showed an excellent detection limit of 90 yoctomoles (~54 molecules) and a wide linear dynamic range of 1.14 zmol/L − 100 pmol/L for TSH. The detection sensitivity was about 4.4 × 109 times higher than conventional enzyme-linked immunosorbent assay and could successfully quantify TSH in human serum. The wavelength-dependent 3D TIRF-SLM technique may emerge as a reliable platform for ultrahigh-sensitive nanobiosensors at the single-molecule level and early diagnosis with quantification of disease-related ultra-trace biomolecules.
Tetrahydro-γ-carbolines (THγCs) constitute one of the most important subtypes of indole alkaloids. In addition to being substructures of natural products, these structural motifs and moieties can often be found in pharmaceuticals due to their diverse bioactivities such as antiviral, antibacterial, antifungal, antiparasitic, antitumor, anti-inflammatory, and neuropharmacological activities. Beyond the pharmacological and biological aspects of these scaffolds, they have considerable synthetic applications for the construction of further bioactive compounds, too. The aim of this review is to summarize recent developments in the synthesis of this compound class.
Ring-opening copolymerization of CO2 and epoxides is a promising way to manufacture high value-added materials. Despite a variety of catalyst systems have been reported, the reaction is still limited by low activity and polymer selectivity. Herein, a strategy of polymerization-enhanced Lewis acidity is reported to construct a series of highly efficient polymeric aluminum porphyrin catalysts (PAPCs). The characterization of the coordination equilibrium constant (Keq) showed significantly enhanced Lewis acidity of PAPC (Keq = 18.2 L/mol) compared to the monomeric counterpart (Keq = 6.4 L/mol), accompanied with increased turnover frequency (TOF) from 136 h−1 to 5500 h−1. Through detailed regulation of Lewis acidity, the highly Lewis acidic PAPC-OTs displayed a record high TOF of 30,200 h−1 with polymer selectivity of up to 99%.
Wettability transition is a significant responsive mechanism which is widely applied to construct smart materials and systems. The broad-spectrum responsiveness of the wettability transition makes it a promising way to expand innovative applications. Here, we develop a track-guided self-transportation system mediated by sequential wettability transition accompanied with capillary transportation. Alkaline fuel is loaded into polydimethylsiloxane (PDMS) cuboid to trigger the wettability transition of distributed superhydrophobic tracks laid in shallow water. After the wettability transition, the induced capillary force can propel the repetitive track-to-track transportation of PDMS. Importantly, the spacing between adjacent tracks is rationally designed based on multiple factors including threshold of wettability transition, diffusion kinetics and capillary interaction. Furthermore, the track-guided transportation system is applied to realize directed self-assembly of multiple PDMS building blocks for designated configuration, which increases the complexity and intelligence of self-assembly systems.
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