Flat bands and magnetism in Fe4GeTe2\mathrm{Fe_4 Ge Te_2} and Fe5GeTe2\mathrm{Fe_5GeTe_2} due to bipartite crystal lattices

$\mathrm{Fe_{n=4,5}GeTe_2}$ exhibits quasi-two-dimensional properties as a promising candidate for a near-room-temperature ferromagnet, which has attracted great interest. In this work, we notice that the crystal lattice of $\mathrm{Fe_{n=4,5}GeTe_2}$ can be approximately considered to be stacked by three bipartite crystal lattices. By combining the model Hamiltonians of bipartite crystal lattices and first-principles calculations, we investigate the electronic structure and the magnetism of $\mathrm{Fe_{n=4,5}GeTe_2}$. We conclude that flat bands near the Fermi level originate from the bipartite crystal lattices and that these flat bands are expected to lead to the itinerant ferromagnetism in $\mathrm{Fe_{n=4,5}GeTe_2}$. Interestingly, we also find that the magnetic moment of the Fe5 atom in $\mathrm{Fe_5 Ge Te_2}$ is distinct from the other Fe atoms and is sensitive with the Coulomb interaction $U$ and external pressure. These findings may be helpful to understand the exotic magnetic behavior of $\mathrm{Fe_{n=4,5} Ge Te_2}$.Comment: 9 pages, 8 figure

Multiple symmetric nonnegative solutions of second-order ordinary differential equations

AbstractThe existence of multiple nonnegative solutions of the equations −χ″ = f(χ, χ′) subject to χ(0) = χ(1) = 0 is studied. The result is obtained that there are at least three symmetric nonnegative solutions if certain conditions are imposed on f

On sign-changing solutions for nonlinear operator equations

AbstractIn this paper, the existence of sign-changing solutions for nonlinear operator equations is discussed by using the topological degree and fixed point index theory. The main theorems are some new three-solution theorems which are different from the famous Amann's and Leggett-Williams' three-solution theorems as well as the results in [F. Li, G. Han, Generalization for Amann's and Leggett–Williams' three-solution theorems and applications, J. Math. Anal. Appl. 298 (2004) 638–654]. These three solutions are all nonzero. One of them is positive, another is negative, and the third one is a sign-changing solution. Furthermore, the theoretical results are successfully applied to both integral and differential equations

Ag–Cu Nanoalloy Electrocatalysts for Oxygen Reduction in Alkaline Media for Advanced Energy Conversion and Storage

Silver-based nanoalloys owing to their cost, performance and stability are an attractive electrocatalyst system for oxygen reduction reaction (ORR) in the alkaline fuel cells and metal air batteries. A systematic computational and experimental approach has been adopted to investigate their performance for ORR in alkaline environment. Firstly, genetic algorithm (GA) based calculations have been performed to look for the stable compositions and structures of these nanoalloys. Later, density functional theory (DFT) is employed to simulate the working of those stable nanoalloys in actual working conditions. Finally, the most promising nanoalloys have been synthesized by physical and chemical routes to confirm their performance in real-life conditions. It has been found that the alloying of silver with copper enhances the catalytic performance of Ag nanoparticles. The enhancement in performance can be related to the modification of the electronic and physical structure of Ag due to copper doping. The superior performance of Ag–Cu nanocatalysts in alkaline fuel cells and metal air batteries along with their modest cost and long-term stability make them a promising candidate for deployment as a catalyst for ORR in alkaline media

Towards Self-Interpretable Graph-Level Anomaly Detection

Graph-level anomaly detection (GLAD) aims to identify graphs that exhibit notable dissimilarity compared to the majority in a collection. However, current works primarily focus on evaluating graph-level abnormality while failing to provide meaningful explanations for the predictions, which largely limits their reliability and application scope. In this paper, we investigate a new challenging problem, explainable GLAD, where the learning objective is to predict the abnormality of each graph sample with corresponding explanations, i.e., the vital subgraph that leads to the predictions. To address this challenging problem, we propose a Self-Interpretable Graph aNomaly dETection model (SIGNET for short) that detects anomalous graphs as well as generates informative explanations simultaneously. Specifically, we first introduce the multi-view subgraph information bottleneck (MSIB) framework, serving as the design basis of our self-interpretable GLAD approach. This way SIGNET is able to not only measure the abnormality of each graph based on cross-view mutual information but also provide informative graph rationales by extracting bottleneck subgraphs from the input graph and its dual hypergraph in a self-supervised way. Extensive experiments on 16 datasets demonstrate the anomaly detection capability and self-interpretability of SIGNET.Comment: 23 pages; accepted to NeurIPS 202

Bifunctional Electrocatalysts for Oxygen Reduction and Borohydride Oxidation Reactions Using Ag3Sn Nanointermetallic for the Ensemble Effect

2017-2018 > Academic research: refereed > Publication in refereed journal201805 bcrcAccepted ManuscriptOthersNational Natural Science Foundation of China; the Research Fund of State Key Laboratory of Solidification Processing in China; the Aeronautic Science Foundation Program of China; the Science and Technology Innovation Fund of Western Metal Materials; the Doctoral Fund of Ministry of Education of ChinaPublishe

Ground-state solutions to a class of modified Kirchhoff-type transmissiom problems with critical perturbation

This paper discusses a class of modified Kirchhoff-type transmission problems with critical perturbation. We establish an existence result of the ground-state solutions by using perturbation methods. Meanwhile, the limit properties of solution sequence are investigated

Ground-state solutions to a class of modified Kirchhoff-type transmissiom problems with critical perturbation

This paper discusses a class of modified Kirchhoff-type transmissiom problems with critical perturbation. We establish an existence result of the ground-state solutions by using perturbation methods. Meanwhile, the limit properties of solution sequence are investigated

Age-related change in muscle strength, muscle mass, and fat mass between the dominant and non-dominant upper limbs

BackgroundAny form of physical activity is recommended for the older adults to maintain their physical function; however, the effect of daily activities on muscle function still needs to be investigated. Humans always use one dominant hand to perform tasks, providing a natural situation for research on the effect of daily activities on muscle function.MethodsFive hundred and twenty-six healthy adults were recruited from the community in Beijing. Muscle strength was assessed using a handgrip dynamometer, lean mass, fat mass, bone area and bone mineral content of upper limbs were assessed using dual-energy X ray-absorptiometry. The results were compared between the dominant and non-dominant upper limbs.ResultsThe dominant upper limb had better muscle strength, lean mass, bone area and bone mineral content than the non-dominant side. The difference in muscle strength and lean mass between the two upper limbs decreased with the advanced age. In older age, fat mass of upper limbs increased in men, but not in women.ConclusionDaily activities can maintain better muscle function in the dominant upper limb than in the non-dominant side; however, the delaying effect on age-related decline in muscle function was limited

Novel regio- and stereoselective phosphonyl radical addition to glycals promoted by Mn(II)-air: syntheses of 1,2-dideoxy 2-C-diphenylphosphinylglycopyranosides

National Natural Science Foundation of China [21272219, 20972142]; State Key Laboratory of Bio-organic and Natural Products Chemistry, CAS [08417]1,2-Dideoxy-2-C-diphenylphosphinylglycopyranosides were first synthesized by the novel Mn(II)-air promoted reaction of diphenylphosphine oxide with various glycals in high yields with excellent regio- and stereoselectivities, which was clarified as a radical addition reaction controlled by the oxygen of vinyl ether