Abstract
The Kagome superconductors AV
3
Sb
5
(A = K, Rb, Cs) have received enormous attention due to their nontrivial topological electronic structure, anomalous physical properties and ...superconductivity. Unconventional charge density wave (CDW) has been detected in AV
3
Sb
5
. High-precision electronic structure determination is essential to understand its origin. Here we unveil electronic nature of the CDW phase in our high-resolution angle-resolved photoemission measurements on KV
3
Sb
5
. We have observed CDW-induced Fermi surface reconstruction and the associated band folding. The CDW-induced band splitting and the associated gap opening have been revealed at the boundary of the pristine and reconstructed Brillouin zones. The Fermi surface- and momentum-dependent CDW gap is measured and the strongly anisotropic CDW gap is observed for all the V-derived Fermi surface. In particular, we have observed signatures of the electron-phonon coupling in KV
3
Sb
5
. These results provide key insights in understanding the nature of the CDW state and its interplay with superconductivity in AV
3
Sb
5
superconductors.
Processability of vitrimers strongly relies on the temperature dependence of viscosity. In this study, we analyzed temperature-dependent viscoelasticity of vitrimers based on the dioxaborolane ...metathesis reaction. A sol-to-gel transition process and a reverse gel-to-sol process are observed in the linear viscoelasticity with increasing content of the cross-linker. The latter gel-to-sol process is owing to a reverse reaction between a two-site interchain cross-linking point with an excess cross-linker, forming two noncross-linking sites. For samples above the gel point, the increasing temperature leads to a weaker acceleration of the decross-linking process than the Rouse-type relaxation, and accordingly, broadening of the plateau region. This trend is easily visualized in samples slightly above the gel point for which the stress relaxation arising from the Rouse-type relaxation and the decross-linking process are not well separated over time. This temperature-dependent behavior reflects a case that the lifetime of the dynamic covalent bond is significantly larger than the Rouse time of the network strands. As a result, the stress borne by a strand relaxes immediately upon decrosslinking, and thus, the low activation energy of the dioxaborolane metathesis reaction governs the strand relaxation.
Two-dimensional (2D) materials have attracted great attention and spurred rapid development in both fundamental research and device applications. The search for exotic physical properties, such as ...magnetic and topological order, in 2D materials could enable the realization of novel quantum devices and is therefore at the forefront of materials science. Here, we report the discovery of twofold degenerate Weyl nodal lines in a 2D ferromagnetic material, a single-layer gadolinium-silver compound, based on combined angle-resolved photoemission spectroscopy measurements and theoretical calculations. These Weyl nodal lines are symmetry protected and thus robust against external perturbations. The coexistence of magnetic and topological order in a 2D material is likely to inform ongoing efforts study the rich physics in 2D topological ferromagnets.
Topological nodal line semimetals, a novel quantum state of materials, possess topologically nontrivial valence and conduction bands that touch at a line near the Fermi level. The exotic band ...structure can lead to various novel properties, such as long-range Coulomb interaction and flat Landau levels. Recently, topological nodal lines have been observed in several bulk materials, such as PtSn4, ZrSiS, TlTaSe2 and PbTaSe2. However, in two-dimensional materials, experimental research on nodal line fermions is still lacking. Here, we report the discovery of two-dimensional Dirac nodal line fermions in monolayer Cu2Si based on combined theoretical calculations and angle-resolved photoemission spectroscopy measurements. The Dirac nodal lines in Cu2Si form two concentric loops centred around the Γ point and are protected by mirror reflection symmetry. Our results establish Cu2Si as a platform to study the novel physical properties in two-dimensional Dirac materials and provide opportunities to realize high-speed low-dissipation devices.
As a new class of environment-friendly materials, vitrimers have attracted growing attention, but their thermodynamics and reaction kinetics are yet to be better understood. In this study, we examine ...the thermodynamics and reaction kinetics of symmetric vitrimers that contain two types of precursors, poly(hexyl methacrylate-random-2,3-dioxaborolanepropyl methacrylate) and poly(hexyl methacrylate-random-4-vinylphenyl-2,3-dioxaborolanepropyl), which can react with each other through dioxaborolane metathesis reaction to form a vitrimer network. The plateau modulus of the vitrimer samples reflects a degree of cross-linking reaction, while the relaxation of the plateau is controlled by the kinetics of the exchange reaction. For each precursor, we prepared a series of samples with similar degrees of polymerization but different average numbers of functional groups per chain, designated as F A and F B, respectively. When F B is fixed, the plateau modulus increases with increasing F A and saturates for sufficiently large F A, while the relaxation rate of the network first decelerates with cross-linking and then accelerates when F A becomes sufficiently high. A similar trend is observed when changing F B at fixed F A due to the symmetric nature of our model system. The saturation of the modulus can be explained by considering the reaction equilibrium established between the A and B groups, and the transition of the relaxation rate can be explained by considering that the reaction rate constant between the cross-linking sites is much lower (∼2 orders lower) than that between one cross-linking site and one dangling functional group.
To address the problem that traditional convolutional neural networks cannot classify facial expression image features precisely, an interpretable face expression recognition method combining ...ResNet18 residual network and support vector machines (SVM) is proposed in the paper. The SVM classifier is used to enhance the matching ability of feature vectors and labels under the expression image feature space, to improve the expression recognition effect of the whole model. The class activation mapping and t-distributed stochastic neighbor embedding methods are used to visualize and interpret facial expression recognition’s feature analysis and decision making under the residual neural network. The experimental results and the interpretable visualization analysis show that the algorithm structure can effectively improve the recognition ability of the network. Under the FER2013, JAFFE, and CK+ datasets, it achieved 67.65%, 84.44%, and 96.94% emotional recognition accuracy, respectively, showing a certain generalization ability and superior performance.
Methanol-gasoline blends have emerged as a promising and environmentally friendly bio-fuel option, garnering widespread attention and promotion globally. The methanol content within these blends ...significantly influences their quality and combustion performance. This study explores the qualitative and qualitative analysis of methanol-gasoline blends using Raman spectroscopy coupled with machine learning methods. Experimentally, methanol-gasoline blends with varying methanol concentrations were artificially configured, commencing with initial market samples. For qualitative analysis, the partial least squares discriminant analysis (PLS-DA) model was employed to classify the categories of blends, demonstrating high prediction performance with an accuracy of nearly 100% classification. For the quantitative analysis, a consensus model was proposed to accurately predict the methanol content. It integrates member models developed on clustered variables, using the unsupervised clustering method of the self-organizing mapping neural network (SOM) to accomplish the regression prediction. The performance of this consensus model was systemically compared to that of the PLS model and uninformative variable elimination (UVE)-PLS model. Results revealed that the unsupervised consensus model outperformed other models in predicting the methanol content across various types of methanol gasoline blends. The correlation coefficients for prediction sets consistently exceeded 0.98. Consequently, Raman spectroscopy emerges as a suitable choice for both qualitative and quantitative analysis of methanol-gasoline blend quality. This study anticipates an increasing role for Raman spectroscopy in analysis of fuel composition.
Background
Epidemiological trends of esophageal cancer attributable to smoking remain unclear. This study aimed to estimate the spatiotemporal trends of the esophageal cancer burden attributable to ...smoking to assist in global esophageal cancer prevention and smoking cessation.
Methods
Data on esophageal cancer attributable to smoking were obtained from the Global Burden of Disease Study 2019. The number and age-standardized rates of esophageal cancer mortality (ASMR) and disability-adjusted life years (ASDR) were analyzed by age, sex, and location. Joinpoint regression analysis was used to analyze the temporal trends of esophageal cancer burden attributable to smoking over 30 years.
Results
In 2019, the number of global esophageal cancer deaths and disability-adjusted life years (DALYs) attributable to smoking was approximately 203,000 and 475 million, respectively. The global esophageal cancer deaths and DALYs due to smoking were approximately 1.5-fold increased from 1990 to 2019, but the corresponding ASMR and ASDR had decreased. The heaviest burden occurred in East Asia, Mongolia, and the middle socio-demographic index (SDI) region. The male-to-female ratio was approximately 12.7 in the esophageal cancer deaths and DALYs and was approximately 14.3 in the ASMR and ASDR. The heaviest burden appeared in the 60–74 years age group. The estimated annual percentage change (EAPC) in ASMR was highly negatively associated with ASMR in 1990 (ρ = −0.41, p < 0.001) and SDI in 2019 (ρ = −0.29, p < 0.001).
Conclusion
Despite reductions in ASMR and ASDR, the esophageal cancer burden attributable to smoking remains heavy, especially in middle SDI regions. Active tobacco control can reduce esophageal cancer burden.
Ferroptosis, a novel type of iron-dependent cell death, plays a vital role in breast cancer progression. However, the function of ferroptosis-induced cancer cell-derived exosomes in breast cancer ...remains unclear. In this study, we attempted to investigate the impact of breast cancer cells-derived exosomes induced by ferroptosis on the polarization of macrophages and the progression of breast cancer.
Erastin was used to induce ferroptosis and breast cancer cell-derived exosomes were identified by transmission electron microscopy. Western blot, quantitative reverse transcription PCR, immunofluorescence, flow cytometry, and ELISA were used to determine the role of exosomes in macrophage polarization. Transwell assays were used to detect breast cancer cell migration, and invasion.
Our results showed that erastin promoted ferroptosis in breast cancer cells with increased Fe2+ level and ROS production. Breast cancer cell-derived exosomes induced by ferroptosis were successfully isolated and verified to be internalized by macrophages. In addition, ferroptosis-induced breast cancer cell-derived exosomes (Fe-exo) remarkably diminished M2 marker, Arg-1 expression. The ratio of CD206
macrophages was significantly decreased after Fe-exo treatment. CD206 protein expression and Arg-1 level were dramatically reduced in M2 macrophages incubated by Fe-exo. Moreover, autophagy PCR array showed that the expression of 84 autophagy-related genes were altered after macrophages were incubated by Fe-exo. Furthermore, macrophages incubated by Fe-exo repressed the migration and invasion of breast cancer cells.
Ferroptosis-dependent cancer cell-derived exosomes inhibited M2 polarization of macrophages, which in turn inhibited migration and invasion of breast cancer cells. This study provides novel therapeutic strategies for patients with breast cancer.
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