Nanographene with a Nitrogen‐Doped Cavity Wang, Fei‐Fan; Wang, Yu‐Xiang; Wu, Qiong ...
Angewandte Chemie International Edition,
January 8, 2024, Volume:
63, Issue:
2
Journal Article
Peer reviewed
Nitrogen‐doped cavities are pervasive in graphenic materials, and represent key sites for catalytic and electrochemical activity. However, their structures are generally heterogeneous. In this study, ...we present the synthesis of a well‐defined molecular cutout of graphene featuring N‐doped cavity. The graphitization of a macrocyclic pyridinic precursor was achieved through photochemical cyclodehydrochlorination. In comparison to its counterpart with pyridinic nitrogen at the edges, the pyridinic nitrogen atoms in this nanographene cavity exhibit significantly reduced basicity and selective binding to Ag+ ion. Analysis of the protonation and coordination equilibria revealed that the tri‐N‐doped cavity binds three protons, but only one Ag+ ion. These distinct protonation and coordination behaviors clearly illustrate the space confinement effect imparted by the cavities.
A nanographene with a tri‐N‐doped cavity was synthesized by photo‐induced cyclization. In comparison with nitrogen‐doping at the edge, this tri‐N‐doped holey nanographene exhibited markedly reduced basicity and selective affinity toward Ag+. This nanographene with a N‐doped cavity provides a precise model for understanding the binding in the nano‐confined defects of graphenic materials.
Anisotropy is an intrinsic property of crystalline materials. However, the photoluminescence anisotropy in eutectic crystals of organometallic complexes has remained unexplored. Herein, the eutectic ...of polynuclear lanthanide complexes and Ag clusters was prepared, and the crystal shows significant photoluminescence anisotropy. The polarization anisotropy of emission δ and degree of excitation polarization P are 2.62 and 0.53, respectively. The rare excitation polarization properties have been proved to be related to the regular arrangement of electric transition dipole moments of luminescent molecules in the crystal. Our design provides a reference for developing new photoluminescence anisotropy materials and expanding their applications.
The eutectic of Ag clusters and polynuclear lanthanide complexes induces fluorescence anisotropy. Investigation of the excitation polarization mechanism confirmed that the electrons in the ground state have higher transition efficiency when the direction of the electric field vibration of the photon and the direction of the molecular electric transition dipole moment are parallel.
Research on the spatiotemporal characteristics and influencing factors of environmental emergency incidents in China in recent decades can improve the effectiveness and accuracy of risk supervision ...of environmental emergency incidents. Based on the data of environmental emergency incidents in 31 provincial regions in China from 1991 to 2018, this study used spatial autocorrelation analysis and a geographically and temporally weighted regression model to analyze the spatial dependence of environmental emergency incidents and the temporal and spatial heterogeneity of influencing factors. The results showed that: ① there was a significant positive spatial correlation between environmental emergency incidents during 1991-1994 and 2001-2014, and the spatial agglomeration was gradually increasing, that is, environmental emergency incidents existed in the provinces of China; clearly, the space depended on the characteristics and was not completely random. ② There was an unbalanced development pattern of environmenta
To clarify the content characteristics of the main active components and mineral elements of Cynomorium songaricum under different habitat conditions, and further explore the relationship between the ...quality of C. songaricum and habitats, this study took C. songaricum from 25 different habitats in China as the research object, and measured the contents of 8 main active components and 12 mineral elements separately. Diversity analysis, correlation analysis, principal component analysis and cluster analysis were carried out. The results showed that the genetic diversity of total flavonoids, ursolic acid, ether extract, potassium(K), phosphorus(P) and zinc(Zn) in C. songaricum was high. The coefficient of variation of crude polysaccharide, ether extract, gallic acid, protocatechuic aldehyde, catechin, epicatechin, calcium(Ca), sodium(Na), magnesium(Mg), sulfur(S), iron(Fe), manganese(Mn), selenium(Se) and nickel(Ni) were all over 36%, indicating that the quality of C. songaricum was significantly affected by hab
1 Most patients with cryptorchidism have this condition corrected by surgery before puberty. ...adult bilateral cryptorchidism (BC) is not observed frequently in clinical practice. According to the ...location of testicles, preoperative examination results, and doctors' experience, open or laparoscopic surgery was selected. ...the sample size was small and follow-up time was short.
As an advanced near-net shape technology, squeeze casting is an excellent method for producing high integrity castings. Numerical simulation is a very effective method to optimize squeeze casting ...process, and the interfacial heat transfer coefficient（IHTC） is an important boundary condition in numerical simulation. Therefore, the study of the IHTC is of great significance. In the present study, experiments were conducted and a “plate shape” aluminum alloy casting was cast in H13 steel die. In order to obtain accurate temperature readings inside the die, a special temperature sensor units（TSU） was designed. Six 1 mm wide and 1 mm deep grooves were machined in the sensor unit for the placement of the thermocouples whose tips were welded to the end wall. Each groove was machined to terminate at a particular distance（1, 3, and 6 mm） from the front end of the sensor unit. Based on the temperature measurements inside the die, the interfacial heat transfer coefficient（IHTC） at the metal-die interface was determined by applying an inverse approach. The acquired data were processed by a low pass filtering method based on Fast Fourier Transform（FFT）. The feature of the IHTC at the metal-die interface was discussed.
Background
Glioma, the most frequent primary tumor of the central nervous system, has poor prognosis. The epidermal growth factor receptor (EGFR) pathway and angiogenesis play important roles in ...glioma growth, invasion, and recurrence. The present study aimed to use proteomic methods to probe into the role of the EGF‐EGFR‐angiogenesis axis in the tumorigenesis of glioma and access the therapeutic efficacy of selumetinib on glioma.
Methods
Proteomic profiling was used to characterize 200 paired EGFR‐positive and EGFR‐negative glioma tissues of all pathological types. The quantitative mass spectrometry data were used for systematic analysis of the proteomic profiles of 10 EGFR‐positive and 10 EGFR‐negative glioma cases. Consensus‐clustering analysis was used to screen target proteins. Immunofluorescence analysis, cell growth assay, and intracranial xenograft experiments were used to verify and test the therapeutic effect of selumetinib on glioma.
Results
Advanced proteomic screening demonstrated that the expression of EGF‐like domain multiple 7 (EGFL7) was higher in EGFR‐positive tumor tissues than in EGFR‐negative tumor tissues. In addition, EGFL7 could act as an activator in vitro and in vivo to promote glioma cell proliferation. EGFL7 was associated strongly with EGFR and prognosis. EGFL7 knockdown effectively suppressed glioma cell proliferation. Selumetinib treatment showed tumor reduction effect in EGFR‐positive glioblastoma xenograft mouse model.
Conclusions
EGFL7 is a potential diagnostic biomarker and therapeutic target of glioma. Selumetinib could target the EGFR pathway and possibly improve the prognosis of EGFR‐positive glioma.
Flatness plays a crucial role in determining the quality of products in strip cold rolling. Data driven methods have shown promise in flatness prediction by effectively capturing the nonlinearities ...and strong coupling present in cold rolling processing, surpassing the capability of conventional methods. However, existing data driven models remain restricted by a lack of rolling theory guidance, a black-box nature of predictive processes, and gradient conflict of multi-channel flatness. To overcome these limitations, this paper proposes an interpretable mechanism guided multi-channel distributed meta learning framework for flatness prediction. Initially, significant physic-based parameters, such as theoretical rolling force deviation and tension deviation, and controller parameters are calculated to guide data driven modeling. Subsequently, a distributed meta learning framework is modeled for multi-channel flatness to eliminate gradient conflict. Furthermore, eXplainable Artificial Intelligence (XAI) technique is implemented to ensure the transparent predictive processes of multi-channel flatness. The analysis results present that theoretical parameters and controller parameters effectively improve the performance of flatness prediction. In addition, the comparative results demonstrate that the proposed framework outperforms the existing flatness prediction methods and other state-of-the-art machine learning methods by 4.24%. Importantly, the XAI-based explanation of the proposed framework effectively enhances the credibility of data driven flatness prediction.
Display omitted
•An interpretable distributed meta learning framework is proposed for flatness prediction.•The interpretability and performance of data driven model is enhanced by integrating rolling mechanism.•Distributed learning framework is effective in eliminating gradient conflict of multi-channel flatness in training procedure.•The predictive process of data-driven model in cold rolling is first explained by eXplainable Artificial Intelligence (XAI).
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