2D layered materials have sparked great interest from the perspective of basic physics and applied science in the past few years. Extraordinarily, many novel stacked structures that bring versatile ...properties and applications can be artificially assembled, as exemplified by vertical van der Waals (vdW) heterostructures, twisted multilayer 2D materials, hybrid dimensional structures, etc. Compared with the ordinary synthesis process, the stacking technique is a powerful strategy to achieve high‐quality and freely controlled 2D material stacked structures with atomic accuracy. This review highlights the most advanced stacking techniques involving the preparation, transfer, and stacking of high‐quality single crystal 2D materials. Apart from the 2D–2D stacked structures, 2D–0D, 2D–1D, and 2D–3D structures offer a prospective platform for the increasing application of 2D materials. The assembly strategy and physical properties of these stacked structures strongly depend on the factors in the stacking process, including the surface quality, angle control, and sample size. In addition, comparative analysis tables on the techniques involved are also available. The summary of these strategies and techniques will hopefully provide a valuable reference for relevant work.
2D stacked structures are being rapidly developed. However, the assembly and integration techniques of 2D material‐based devices are still subject to many restrictions, seriously hindering the design and development of new functional devices. As one of the most important aspects, 2D material stacking techniques are systematically summarized and analyzed in this review.
We develop Random Batch Methods for interacting particle systems with large number of particles. These methods use small but random batches for particle interactions, thus the computational cost is ...reduced from O(N2) per time step to O(N), for a system with N particles with binary interactions. On one hand, these methods are efficient Asymptotic-Preserving schemes for the underlying particle systems, allowing N-independent time steps and also capture, in the N→∞ limit, the solution of the mean field limit which are nonlinear Fokker-Planck equations; on the other hand, the stochastic processes generated by the algorithms can also be regarded as new models for the underlying problems. For one of the methods, we give a particle number independent error estimate under some special interactions. Then, we apply these methods to some representative problems in mathematics, physics, social and data sciences, including the Dyson Brownian motion from random matrix theory, Thomson's problem, distribution of wealth, opinion dynamics and clustering. Numerical results show that the methods can capture both the transient solutions and the global equilibrium in these problems.
Background and Objective
Periodontitis is a multifactorial disease that can lead to the progressive destruction of dental support tissue. However, the detailed mechanisms and specific biomarkers ...involved in periodontitis remain to be further studied. Recently, long non‐coding RNAs (lncRNAs) have been found to play a more important role than other types of RNAs. In our study, we analysed the expression of lncRNAs in periodontitis by analysing GSE16134.
Material and Methods
We identified highly correlated genes by analysing GSE16134 with weighted gene co‐expression network analysis (WGCNA) and identified 50 hub lncRNAs that were dysregulated. Then, we used the Linear Models for Microarray Data (Limma) package to identify the hub lncRNAs that were differentially expressed (DElncRNAs). The ceRNA co‐expression network data were obtained from several sites, including miRcode, and were used to assess the potential WGCNA function of hub DElncRNAs in periodontitis. Besides, we divided the samples into LBX2‐AS1 high and low expression group by the expression level of LBX2‐AS1 and calculated DEG by Limma package. Furthermore, we performed GO function, KEGG pathway and GSEA enrichment of DEGs.
Results
In the analysis, we identified 50 hub lncRNAs that may play important roles in periodontitis. Then, we used the Limma package to identify 3 hub DElncRNAs (LINC00687, LBX2‐AS1 and LINC01566). We elucidated the potential function of the hub DElncRNA LBX2‐AS1 in periodontitis by constructing a co‐expression network of lncRNA‐miRNA‐mRNA interactions. Totally, 573 DEGs (354 up‐ and 219 downregulated) in periodontitis samples were identified. DEGs were enriched in different GO terms and pathways, such as neutrophil degranulation, neutrophil activation, neutrophil activation involved in immune response, neutrophil‐mediated immunity, antigen processing and presentation, JAK‐STAT signalling pathway, natural killer cell‐mediated cytotoxicity, EGFR tyrosine kinase inhibitor resistance, phosphatidylinositol signalling system and Vascular Endothelial Growth Factor (VEGF) signalling pathway.
Conclusion
In our study, we found that 3 hub DElncRNAs (LINC00687, LBX2‐AS1 and LINC01566) may be involved in the pathogenesis of periodontitis based on WGCNA and Limma analysis. Our study aimed to elucidate the mechanisms involved in periodontitis at the genetic and epigenetic levels by constructing a ceRNA network associated with lncRNA. Besides, identification DEGs of differential LBX2‐AS1 and functional annotation showed that LBX2‐AS1 might be associated with periodontitis.
Highly active and stable bifunctional electrocatalysts for overall water splitting are important for clean and renewable energy technologies. The development of energy‐saving electrocatalysts for ...hydrogen evolution reaction (HER) by replacing the sluggish oxygen evolution reaction (OER) with a thermodynamically favorable electrochemical oxidation (ECO) reaction has attracted increasing attention. In this study, a self‐supported, hierarchical, porous, nitrogen‐doped carbon (NC)@CuCo2Nx/carbon fiber (CF) is fabricated and used as an efficient bifunctional electrocatalyst for both HER and OER in alkaline solutions with excellent activity and stability. Moreover, a two‐electrode electrolyzer is assembled using the NC@CuCo2Nx/CF as an electrocatalyst at both cathode and anode electrodes for H2 production and selective ECO of benzyl alcohol with high conversion and selectivity. The excellent electrocatalytic activity is proposed to be mainly due to the hierarchical architecture beneficial for exposing more catalytic active sites, enhancing mass transport. Density functional theoretical calculations reveal that the adsorption energies of key species can be modulated due to the synergistic effect between CoN and CuN. This work provides a reference for the development of high‐performance bifunctional electrocatalysts for simultaneous production of H2 and high‐value‐added fine chemicals.
Hierarchical porous nitrogen‐doped carbon@CuCo2Nx/carbon fiber serving as an efficient bifunctional electrocatalyst for overall water splitting and selective electrooxidation of benzyl alcohol with excellent activity and stability is reported. The outstanding electrocatalytic performance is mainly due to the hierarchical architecture and the synergistic effects between the Co5.47N, Cu3N nanoparticles.
The (3 + 1)-dimensional Painlevé integrable equation are a class of nonlinear differential equations with special properties, which play an important role in nonlinear science and are of great ...significance in solving various practical problems, such as many important models in fields such as quantum mechanics, statistical physics, nonlinear optics, and celestial mechanics. In this work, we utilize the Hirota bilinear form and Mathematica software to formally obtain the interaction solution among lump wave, solitary wave and periodic wave, which has not yet appeared in other literature. Additionally, using the
-expansion method, we provide a rich set of exact solutions for the (3 + 1)-dimensional Painlevé integrable equation, which includes two functions with arbitrary values. This method is the first to be applied to the (3 + 1)-dimensional Painlevé integrable equation. By giving some 3D graphics and density maps, the dynamic properties are analyzed and demonstrated, which is beneficial for promoting understanding and application of the (3 + 1)-dimensional Painlevé integrable equation.
By utilizing the Hirota’s bilinear form and symbolic computation, abundant lump solutions and lump–kink solutions of the new (3 + 1)-dimensional generalized Kadomtsev–Petviashvili equation are ...derived in this work. Meanwhile, the interaction between lump solutions and the exponential function is also investigated. The dynamic properties of these obtained lump and interaction solutions are analyzed and described in figures by selecting appropriate parameters.
The (G′∕G)-expansion approach is an efficient and well-developed approach to solve nonlinear partial differential equations. In this paper, the (3+1)-dimensional Boiti–Leon–Manna–Pempinelli equation ...is investigated by using this approach, which describes the (2+1)-dimensional interaction of the Riemann wave propagated along the y-axis with a long wave propagated along the x-axis and can be considered as a model for the incompressible fluid. With the aid of symbolic computation, a family of exact solutions are obtained in forms of the hyperbolic functions and the trigonometric functions. When the parameters are selected special values, non-traveling wave solutions are also presented, and these gained solutions have abundant structures. The figures corresponding to these solutions are illustrated to show the particular localized excitations and the interactions between two solitary waves.
Fe/N/C is a promising non‐Pt electrocatalyst for the oxygen reduction reaction (ORR), but its catalytic activity is considerably inferior to that of Pt in acidic medium, the environment of polymer ...electrolyte membrane fuel cells (PEMFCs). An improved Fe/N/C catalyst (denoted as Fe/N/C‐SCN) derived from Fe(SCN)3, poly‐m‐phenylenediamine, and carbon black is presented. The advantage of using Fe(SCN)3 as iron source is that the obtained catalyst has a high level of S doping and high surface area, and thus exhibits excellent ORR activity (23 A g−1 at 0.80 V) in 0.1 M H2SO4 solution. When the Fe/N/C‐SCN was applied in a PEMFC as cathode catalyst, the maximal power density could exceed 1 W cm−2.
A non‐precious Fe/N/C electrocatalyst was prepared through pyrolysis of Fe(SCN)3, poly‐m‐phenylenediamine, and carbon black. The obtained Fe/N/C catalyst has high level of S doping and high surface area, and thus exhibits excellent catalytic activity for the oxygen reduction reaction in acidic solution. A polymer electrolyte membrane fuel cell using this catalyst as the cathode can yield a maximal power density as high as 1.03 W cm−2.
This paper investigates Cauchy problems for nonlinear fractional time–space generalized Keller–Segel equation Dtβ0cρ+(−△)α2ρ+∇⋅(ρB(ρ))=0, where Caputo derivative Dtβ0cρ models memory effects in time, ...fractional Laplacian (−△)α2ρ represents Lévy diffusion and B(ρ)=−sn,γ∫Rnx−y|x−y|n−γ+2ρ(y)dy is the Riesz potential with a singular kernel which takes into account the long rang interaction. We first establish Lr−Lq estimates and weighted estimates of the fundamental solutions (P(x,t),Y(x,t)) (or equivalently, the solution operators (Sαβ(t),Tαβ(t))). Then, we prove the existence and uniqueness of the mild solutions when initial data are in Lp spaces, or the weighted spaces. Similar to Keller–Segel equations, if the initial data are small in critical space Lpc(Rn) (pc=nα+γ−2), we construct the global existence. Furthermore, we prove the L1 integrability and integral preservation when the initial data are in L1(Rn)∩Lp(Rn) or L1(Rn)∩Lpc(Rn). Finally, some important properties of the mild solutions including the nonnegativity preservation, mass conservation and blowup behaviors are established.
Making use of the Hirota’s bilinear form, lump-type solutions for the (2+1)-dimensional generalized fifth-order KdV equation are presented. The interactions between lump-type solutions and double ...exponential function are discussed. The physical structure and characteristics for these obtained solutions are demonstrated in some three-dimensional plots and corresponding contour plots.
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