Electrochemiluminescence (ECL) plays a key role in analysis and sensing because of its high sensitivity and low background. Its wide applications are however limited by a lack of highly tunable ECL ...luminophores. Here we develop a scalable method to design ECL emitters of covalent organic frameworks (COFs) in aqueous medium by simultaneously restricting the donor and acceptor to the COFs' tight electron configurations and constructing high-speed charge transport networks through olefin linkages. This design allows efficient intramolecular charge transfer for strong ECL, and no exogenous poisonous co-reactants are needed. Olefin-linked donor-acceptor conjugated COFs, systematically synthesized by combining non-ECL active monomers with C
or C
symmetry, exhibit strong ECL signals, which can be boosted by increasing the chain length and conjugation of monomers. The present concept demonstrates that the highly efficient COF-based ECL luminophores can be precisely designed, providing a promising direction toward COF-based ECL phosphors.
Covalent organic frameworks (COFs) have been proposed for electrochemical energy storage, although the poor conductivity resulted from covalent bonds limits their practical performance. Here, we ...propose to introduce noncovalent bonds in COFs through a molecular insertion strategy for improving the conductivity of the COFs as supercapacitor. The synthesized COFs (MI−COFs) establish equilibriums between covalent bonds and noncovalent bonds, which construct a continuous charge transfer channel to enhance the conductivity. The rapid charge transfer rate enables the COFs to activate the redox sites, bringing about excellent electrochemical energy storage behavior. The results show that the MI−COFs exhibit much better performance in specific capacitance and capacity retention rate than those of most COFs‐based supercapacitors. Moreover, through simply altering inserted guests, the mode and strength of noncovalent bond can be adjusted to obtain different energy storage characteristics. The introduction of noncovalent bonds is an effective and flexible way to enhance and regulate the properties of COFs, providing a valuable direction for the development of novel COFs‐based energy storage materials.
A molecular insertion strategy is used by introducing non‐covalent interactions in COFs to form a continuous charge transfer channel and accelerate the charge transfer rate. Meanwhile, the enhanced conductivity activates the redox sites in the COF skeleton, resulting in excellent energy storage performance. In addition, the energy storage behavior can be accurately regulated by changing the type of insertion guests.
At present, poor stability and carrier transfer efficiency are the main problems that limit the development of perovskite‐based photoelectric technologies. In this work, hydrogen‐bonded ...cocrystal‐coated perovskite composite (PeNCs@NHS‐M) is easily obtained by inducing rapid crystallization of melamine (M) and N‐hydroxysuccinimide (NHS) with PeNCs as the nuclei. The outer NHS‐M cocrystal passivates the undercoordinated lead atoms by forming covalent bonds, thereby greatly reducing the trap density while maintaining good structure stability for perovskite nanocrystals. Moreover, benefiting from the interfacial covalent band linkage and long‐range ordered structures of cocrystals, the charge transfer efficiency is effectively enhanced and PeNCs@NHS−M displays superior photoelectric performance. Based on the excellent photoelectric performance and abundant active sites of PeNCs@NHS−M, photocatalytic reduction of uranium is realized. PeNCs@NHS−M exhibits U(VI) reduction removal capability of up to 810.1 mg g−1 in the presence of light. The strategy of cocrystals trapping perovskite nanocrystals provides a simple synthesis method for composites and opens up a new idea for simultaneously improving the stability and photovoltaic performance of perovskite.
The CsPbBr3 nanocrystals (PeNCs) are coated with hydrogen‐bonded cocrystals (N‐hydroxysuccinimide‐melamine, NHS‐M) to achieve defect passivation and structural stability enhancement. Moreover, this covalently linked heterostructure further promotes the electron transport of PeNCs and realizes the photocatalytic reduction of uranium through the binding sites on the cocrystal.
This research investigates the psychological and behavioural mechanisms of college students' aesthetic behaviours. A survey was administered to 1,060 students attending general undergraduate ...universities and measured four structured scales: aesthetic cognition, aesthetic emotion, aesthetic value tendency and aesthetic behaviour. The responses were scored with a 5-point Likert scale. Structural equation modelling was used to construct the measurement model and structural model. The survey results indicate a positive correlation among the four variables. Second, aesthetic cognition has a direct and positive predictive effect on college students' daily aesthetic practices. Furthermore, aesthetic cognition influences aesthetic behaviour through the chain mediating effect of aesthetic feeling and aesthetic preference. Accordingly, we conclude that the concrete path and mechanism of college students' aesthetic cognitions affect their aesthetic behaviours. Specifically, college students' aesthetic cognitive abilities are conducive to their cognitions of positive aesthetic feelings and their cultivation of aesthetic standards, boosting the development of their daily aesthetic practice.
The extraordinary thermal and elastic properties of graphene, mainly originating from its unique acoustic phonon branches near Γ point in Brillouin zone, have attracted great attention in its ...fundamental researches and practical applications. Here, we introduce an optical technique to accurately probe longitudinal acoustic (LA) and transverse acoustic (TA) phonon branches of graphene near Γ point by double resonant Raman scattering of the combination phonon modes in the range of 1650−2150 cm−1 along with the overtone 2D' mode at ∼3200 cm−1. The corresponding sound velocities (νTA=12.9km/s,νLA=19.9km/s) of graphene have been accessed, which are about 10% smaller than those of graphite. Based on νTA and νLA, the two-dimensional (2d) elastic stiffness (tension) coefficients c11 and c66, Young's modulus Y2d and Poisson's ratio σ2d can be estimated. The results demonstrate again that double resonant Raman spectroscopy is a powerful tool to probe the fundamental properties of graphene.
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In this paper, density functional theory (DFT) was used to study the reaction mechanism of the production of hydrogen peroxide from oxygen and water catalyzed by graphene supported metal (Al, Zn, and ...Fe) catalysts. By comparing the supported stability of metal at different sites on graphene surface, the optimal support sites are determined and then a stable catalyst model is selected. Two different reaction paths for the synthesis of hydrogen peroxide and a competitive reaction path for the generation of hydrogen are discussed, the microscopic reaction mechanism of the synthesis of hydrogen peroxide catalyzed by water and oxygen is investigated in detail. The stable structures of reactants, intermediates, and products in each path are optimized. By comparing the activation energies of different reaction paths, the optimal reaction paths are obtained, and the possibility of side reaction products is predicted. At the same time, the electron density, band structure, and density of states characteristics of these graphene supported metal catalysts are studied. The correlation between the physical properties of the three catalysts and their catalytic performances is analyzed. It is predicted that Al, Zn, and Fe catalysts supported by graphene may have the ability to directly generate hydrogen peroxide in industrial wastewater treatment.
The reaction mechanism of R‐GR surface catalyzing the formation of H2O and O2 was studied by density functional theory.
Posterior capsule opacification (PCO) is the most common complication after cataract surgery. So far, the only method for PCO treatment is the precisely focused laser surgery. However, it causes ...severe complications such as physical damages and neuron impairments. Here, a nanostructured photothermal ring integrated intraocular lens (Nano‐IOLs) is reported, in which the rim of commercially available IOLs (C‐IOLs) is decorated with silica coated Au nanorods (Au@SiO2), for high‐efficient prevention of PCO after cataract surgery. The Nano‐IOLs is capable of eliminating the residual lens epithelial cells (LECs) around Nano‐IOLs under mild laser treatment and block the formation of disordered LECs fibrosis, which eventually leads to the loss of vision. The Nano‐IOLs shows good biocompatibility as well as extraordinary region‐confined photothermal effect. In vivo studies reveal that PCO occurrence in rabbit models is about 30%–40% by using Nano‐IOLs, which is significantly lower than the control group that treated with C‐IOLs (100% PCO occurrence) 30 d postsurgery. To the best of our knowledge, it is the first example to integrate nanotechnology with intraocular implants aiming to clinically relevant PCO. Our findings indicate that spatial controllability of photothermal effect from nanomaterials may provide a unique way to intervene the PCO‐induced loss of vision.
An intraocular lens with a Au@SiO2 nanorod‐modified rim (Nano‐IOLs) is reported. Compared to the commercially available IOLs, these Nano‐IOLs retain the intrinsic biocompatibility and optical properties and meanwhile exhibit extraordinary region‐confined photothermal effect. In vitro and rabbit experimental results confirm that the Nano‐IOLs can effectively kill LECs near to the rim and effectively prevent the occurrence of posterior capsule opacification.
By introducing anisotropic micropatterns on a superhydrophobic surface, we demonstrate that water microdroplets can coalesce and leap over the surface spontaneously along a prescribed direction. This ...controlled behavior is attributed to anisotropic liquid–solid adhesion. An analysis relating the preferential leaping probability to the geometrical parameters of the system is presented with consistent experimental results. Surfaces with this rare quality demonstrate many unique characteristics, such as self‐powered, and relatively long‐distance transport of microdroplets by “relay” coalescence‐induced leaping.
Jumping Jack Flash: Water microdroplets can coalesce and leap over the surface spontaneously along a prescribed direction upon introducing anisotropic micropatterns onto superhydrophobic surfaces. These surfaces offer efficient self‐powered and relatively long‐distance transport of microdroplets by “relay” coalescence‐induced leaping and effective self‐sustained microcarriers.
An efficient, Pd(OAc)2 catalyzed method for direct olefination of highly electron-deficient perfluoroarenes was developed. The reaction scope includes a series of activated and nonactivated alkenes ...in moderate to high yields with moderate to high regio- and stereoselectivities.
The phosphatidylinositol-3-kinase (PI3K) / protein kinase B (AKT) signal transduction pathway is commonly misregulated in lymphoma and associated with tumorigenesis and enhanced resistance to ...radiotherapy. Curcumin has been shown to inhibit the PI3K/AKT signal transduction pathway in several tumor models. In this study, we found that curcumin inhibits constitutive and radiation-induced expression of the PI3K/AKT pathway and its downstream regulator nuclear factor kappaB (NF-κB) in human Burkitt’s lymphoma, a high-grade non-Hodgkin’s lymphoma (NHL). We further demonstrated that the blockage of radiation-induced activation of the PI3K/AKT pathway and its downstream regulator NF-κB by either curcumin or specific PI3/AKT inhibitors (LY294002 for PI3K or SH-5 for AKT) enhance apoptosis in three human Burkitt’s lymphoma cell lines (Namalwa, Ramos, and Raji) that were treated with ionizing radiation. However, no synergic effect on radiation-induced apoptosis was found in the cells co-pretreated with curcumin combined with LY294002 or curcumin combined with SH-5. The results from this study suggest that curcumin might play an important role in radiotherapy of high-grade NHL through inhibition of the PI3K/AKT-dependent NF-κB pathway.
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