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Although great progress has been made in artificial enzyme engineering, their catalytic performance is far from satisfactory as alternatives of natural enzymes. Here, we report a novel and efficient strategy to access high-performance nanozymes via direct atomization of platinum nanoparticles (Pt NPs) into single atoms by reversing the thermal sintering process. Atomization of Pt NPs into single atoms makes metal catalytic sites fully exposed and results in engineerable structural and electronic properties, thereby leading to dramatically enhanced enzymatic performance. As expected, the as-prepared thermally stable Pt single-atom nanozyme (PtTS-SAzyme) exhibited remarkable peroxidase-like catalytic activity and kinetics, far exceeding the Pt nanoparticle nanozyme. The following density functional theory calculations revealed that the engineered P and S atoms not only promote the atomization process from Pt NPs into PtTS-SAzyme but also endow single-atom Pt catalytic sites with a unique electronic structure owing to the electron donation of P atoms, as well as the electron acceptance of N and S atoms, which simultaneously contribute to the substantial enhancement of the enzyme-like catalytic performance of PtTS-SAzyme. This work demonstrates that thermal atomization of the metal nanoparticle-based nanozymes into single-atom nanozymes is an effective strategy for engineering high-performance nanozymes, which opens up a new way to rationally design and optimize artificial enzymes to mimic natural enzymes.

Proton-exchange membrane fuel cells (PEMFCs) are a promising new energy-conversion technology due to their safe and environmentally friendly characteristics in a wide range of operating conditions. However, catalysis of the acidic oxygen reduction reaction (ORR) at the cathode is the main obstacle. In this regard, platinum-free single-atomic-site catalysts (SACs) with designable active sites are a potential solution. Unlike catalysts for the ORR in alkaline media that have been widely explored, there is still a gap between the performance of SACs and Pt-based catalysts in acidic media. In this review, we introduce the latest progress of SACs in acidic ORR. SACs consist of metal centers and substrates. We conclude controllable synthetic strategies for SACs from single-atomic sites and substrate design, discuss the relationship between the structure of single-atom sites and acidic ORR performance of SACs at the atomic level, and propose challenges and perspectives of SACs in acidic ORR.

(Quasi-)one-dimensional systems exhibit various fascinating properties such as Luttinger liquid behavior, Peierls transition, novel topological phases, and the accommodation of unique quasiparticles (e.g., spinon, holon, and soliton, etc.). Here we study molybdenum blue bronze A0.3MoO3 (A = K, Rb), a canonical quasi-one-dimensional charge-density-wave material, using laser-based angle-resolved photoemission spectroscopy. Our experiment suggests that the normal phase of A0.3MoO3 is a prototypical Luttinger liquid, from which the charge-density-wave emerges with decreasing temperature. Prominently, we observe strong renormalizations of band dispersions, which is recognized as the spectral function of Holstein polaron derived from band-selective electron-phonon coupling in the system. We argue that the strong electron-phonon coupling plays a dominant role in electronic properties and the charge-density-wave transition in blue bronzes. Our results not only reconcile the long-standing heavy debates on the electronic properties of blue bronzes but also provide a rare platform to study novel composite quasiparticles in Luttinger liquid materials., 19 pages, 4 figures, accepted by Nature Communications

Developing artificial enzymes with the excellent catalytic performance of natural enzymes has been a long-standing goal for chemists. Single-atom catalysts with well-defined atomic structure and electronic coordination environments can effectively mimic natural enzymes. Here, we report an engineered FeN3P-centred single-atom nanozyme (FeN3P-SAzyme) that exhibits comparable peroxidase-like catalytic activity and kinetics to natural enzymes, by controlling the electronic structure of the single-atom iron active centre through the precise coordination of phosphorus and nitrogen. In particular, the engineered FeN3P-SAzyme, with well-defined geometric and electronic structures, displays catalytic performance that is consistent with Michaelis–Menten kinetics. We rationalize the origin of the high enzyme-like activity using density functional theory calculations. Finally, we demonstrate that the developed FeN3P-SAzyme with superior peroxidase-like activity can be used as an effective therapeutic strategy for inhibiting tumour cell growth in vitro and in vivo. Therefore, SAzymes show promising potential for developing artificial enzymes that have the catalytic kinetics of natural enzymes. Nanozymes can provide cost and stability advantages over natural enzymes, but they usually display low catalytic activity and inferior kinetics. Now, a highly active nanozyme is developed that shows comparable kinetics to horseradish peroxidase in the oxidation of a commonly used artificial substrate.

Regulating the selectivity of catalysts in selective hydrogenation reactions at the atomic level is highly desirable but remains a grand challenge. Here we report a simple and practical strategy to synthesize a monolithic single-atom catalyst (SAC) with isolated Pd atoms supported on bulk nitrogen-doped carbon foams (Pd-SAs/CNF). Moreover, we demonstrate that the single-atom Pd sites with unique electronic structure endow Pd-SAs/CNF with an isolated site effect, leading to excellent activity and selectivity in 4-nitrophenylacetylene semi-hydrogenation reaction. In addition, benefiting from the great integrity and excellent mechanical strength, monolithic Pd-SAs/CNF catalyst is easy to separate from the reaction system for conducting the subsequent recycling. The cyclic test demonstrates the excellent reusability and stability of monolithic Pd-SAs/CNF catalyst. The discovery of isolated site effect provides a new approach to design highly selective catalysts. And the development of monolithic SACs provides new opportunities to advance the practical applications of single-atom catalysts.

The electrochemical CO2 reduction reaction (CO2RR) is viewed as a promising way to remove the greenhouse gas CO2 from the atmosphere and convert it into useful industrial products such as methane, methanol, formate, ethanol, and so forth. Single-atom site catalysts (SACs) featuring maximum theoretical atom utilization and a unique electronic structure and coordination environment have emerged as promising candidates for use in the CO2RR. The electronic properties and atomic structures of the central metal sites in SACs will be changed significantly once the types or coordination environments of the central metal sites are altered, which appears to provide new routes for engineering SACs for CO2 electrocatalysis. Therefore, it is of great importance to discuss the structural regulation of SACs at the atomic level and their influence on CO2RR activity and selectivity. Despite substantial efforts being made to fabricate various SACs, the principles of regulating the intrinsic electrocatalytic performances of the single-atom sites still needs to be sufficiently emphasized. In this perspective article, we present the latest progress relating to the synthesis and catalytic performance of SACs for the electrochemical CO2RR. We summarize the atomic-level regulation of SACs for the electrochemical CO2RR from five aspects: the regulation of the central metal atoms, the coordination environments, the interface of single metal complex sites, multi-atom active sites, and other ingenious strategies to improve the performance of SACs. We highlight synthesis strategies and structural design approaches for SACs with unique geometric structures and discuss how the structure affects the catalytic properties., Electrochemical CO2 reduction reaction (CO2RR) is a promising way to remove CO2 and convert it into useful industrial products. Single-atom site catalysts provide opportunities to regulate the active sites of CO2RR catalysts at the atomic level.

Single-atom catalysts not only maximize metal atom efficiency, they also display properties that are considerably different to their more conventional nanoparticle equivalents, making them a promising family of materials to investigate. Herein we developed a general host–guest strategy to fabricate various metal single-atom catalysts on nitrogen-doped carbon (M1/CN, M = Pt, Ir, Pd, Ru, Mo, Ga, Cu, Ni, Mn). The iridium variant Ir1/CN electrocatalyses the formic acid oxidation reaction with a mass activity of 12.9 $${{{\rm{A}}\,{\rm{mg}}^{-1}_{{\rm{Ir}}}}}$$ whereas an Ir/C nanoparticle catalyst is almost inert (~4.8 × 10−3 $${{{\rm{A}}\,{\rm{mg}}^{-1}_{{\rm{Ir}}}}}$$). The activity of Ir1/CN is also 16 and 19 times greater than those of Pd/C and Pt/C, respectively. Furthermore, Ir1/CN displays high tolerance to CO poisoning. First-principle density functional theory reveals that the properties of Ir1/CN stem from the spatial isolation of iridium sites and from the modified electronic structure of iridium with respect to a conventional nanoparticle catalyst. Single-atom catalysts maximize metal atom efficiency and exhibit properties that can be considerably different to their nanoparticle equivalent. Now a general host–guest strategy to make various single-atom catalysts on nitrogen-doped carbon has been developed; the iridium variant electrocatalyses the formic acid oxidation reaction with high mass activity and displays high tolerance to CO poisoning.

The solar-driven photocatalytic reduction of CO2 (CO2 RR) into chemical fuels is a promising route to enrich energy supplies and mitigate CO2 emissions. However, low catalytic efficiency and poor selectivity, especially in a pure-water system, hinder the development of photocatalytic CO2 RR owing to the lack of effective catalysts. Herein, we report a novel atom-confinement and coordination (ACC) strategy to achieve the synthesis of rare-earth single erbium (Er) atoms supported on carbon nitride nanotubes (Er1 /CN-NT) with a tunable dispersion density of single atoms. Er1 /CN-NT is a highly efficient and robust photocatalyst that exhibits outstanding CO2 RR performance in a pure-water system. Experimental results and density functional theory calculations reveal the crucial role of single Er atoms in promoting photocatalytic CO2 RR.

Manipulating metal atoms in a controllable way for the synthesis of materials with the desired structure and properties is the holy grail of chemical synthesis. The recent emergence of single atomic site catalysts (SASC) demonstrates that we are moving toward this goal. Owing to the maximum efficiency of atom-utilization and unique structures and properties, SASC have attracted extensive research attention and interest. The prerequisite for the scientific research and practical applications of SASC is to fabricate highly reactive and stable metal single atoms on appropriate supports. In this review, various synthetic strategies for the synthesis of SASC are summarized with concrete examples highlighting the key issues of the synthesis methods to stabilize single metal atoms on supports and to suppress their migration and agglomeration. Next, we discuss how synthesis conditions affect the structure and catalytic properties of SASC before ending this review by highlighting the prospects and challenges for the synthesis as well as further scientific researches and practical applications of SASC.

Background Although cyclin-dependent kinase inhibitor 2B antisense RNA 1 (CDKN2B-AS1) is upregulated in glioma, its function and potential mechanism in glioma remain unclear. Methods CDKN2B-AS1 level in glioma tissues and cell lines LN229, U251, and U87 was measured by qRT-PCR. Loss of function assays using short hairpin RNA for CDKN2B-AS1 (sh-CDKN2B-AS1) were performed to evaluate the effect of CDKN2B-AS1 on cell invasion, migration, proliferation, and apoptosis. The relationship among CDKN2B-AS1, miR-199a-5p, and DDR1 was determined by bioinformatics analysis and luciferase reporter assay. Rescue experiments were conducted to explore the function of CDKN2B-AS1 and miR-199a-5p in glioma. An in vivo animal model of lentivirally transduced U87 glioma xenografts in mice was established to confirm the role of CDKN2B-AS1. Results CDKN2B-AS1 is significantly upregulated in glioma tissues and cell lines. CDKN2B-AS1 knockdown significantly inhibits cell proliferation, invasion, and migration, while promotes apoptosis of glioma cell lines U251 and U87. Further, a miR-199a-5p inhibitor attenuates the inhibitory effects of sh-CDKN2B-AS1 on these cell phenotypes. CDKN2B-AS1 positively regulates DDR1 expression by directly sponging miR-199a-5p. Moreover, CDKN2B-AS1 knockdown efficiently inhibits U87 tumor xenograft growth in mice. Conclusion Our study reveals that CDKN2B-AS1 promotes glioma development by regulating the miR-199a-5p/DDR1 axis, suggesting that this lncRNA might be a potential therapeutic target.

When conducting a numerical simulation of a train’s derailment and post-derailment, it is necessary to continuously observe the relative position of the wheel and rail, which is of great significance for the correct evaluation of train safety. In this paper, a non-analytic method is proposed to extend the search range and improve the accuracy of the classical semi-analytical method, i.e. the contact locus method. Based on the point cloud convex hull, a high-density wheel contact locus vertical profile is obtained by projecting the chamfer and internal zone of the flange onto the rail cutting plane. To obtain maximum compression in the normal direction and avoid singularities on both rail head sides in the Cartesian coordinate system the rail surface is interpolated with the polar spline curve. Compared with the classical method used to describe the wheel contact locus, in the proposed hybrid method, potential contact points are provided. Finally, the proposed hybrid method and the classical methods are applied to the wheel track coupling simulation. Numerical results demonstrate the high reliability and effectiveness of the proposed method.

It is highly desirable but challenging to optimize the structure of photocatalysts at the atomic scale to facilitate the separation of electron-hole pairs for enhanced performance. Now, a highly efficient photocatalyst is formed by assembling single Pt atoms on a defective TiO2 support (Pt1 /def-TiO2 ). Apart from being proton reduction sites, single Pt atoms promote the neighboring TiO2 units to generate surface oxygen vacancies and form a Pt-O-Ti3+ atomic interface. Experimental results and density functional theory calculations demonstrate that the Pt-O-Ti3+ atomic interface effectively facilitates photogenerated electrons to transfer from Ti3+ defective sites to single Pt atoms, thereby enhancing the separation of electron-hole pairs. This unique structure makes Pt1 /def-TiO2 exhibit a record-level photocatalytic hydrogen production performance with an unexpectedly high turnover frequency of 51423 h-1 , exceeding the Pt nanoparticle supported TiO2 catalyst by a factor of 591.

Here, we successfully developed nanostructured PtNi particles supported on nitrogen-doped carbon (NC), which were obtained by carbonization of metal-organic frameworks under different temperatures, forming the nano-PtNi/NC-600, nano-PtNi/NC-800, nano-PtNi/NC-900 and nano-PtNi/NC-1000 catalysts. For hydrosilylation of 1-octene, we found that the nano-PtNi/NC-1000 catalyst exhibits higher activity for anti-Markovnikov hydrosilylation of 1-octene than those of nano-PtNi/NC-600, nano-PtNi/NC-800, nano-PtNi/NC-900 catalysts. Experiments have verified that benefiting from obvious charge transfer from nano-PtNi particles to NC support carbonized at 1,000 °C, the nano-PtNi/NC-1000 catalyst achieved almost complete conversion and produce exclusive adduct for anti-Markovnikov hydrosilylation of 1-octene. Importantly, the nano-PtNi/NC-1000 catalyst exhibited good reusability for the hydrosilylation reaction. This work provides a new path to optimize electronic structure of catalysts by support modification to enhance electron transfer between metal active species and supports for highly catalytic performance.

Synchronous liver metastasis (SLM) remains a major challenge for rectal cancer. Early detection of SLM is a key factor to improve the survival rate of rectal cancer. In this radiomics study, we predicted the SLM based on the radiomics of primary rectal cancer. A total of 328 radiomics features were extracted from the T2WI images of 194 patients. The least absolute shrinkage and selection operator (LASSO) regression was used to reduce the feature dimension and to construct the radiomics signature. after LASSO, principal component analysis (PCA) was used to sort the features of the surplus characteristics, and selected the features of the total contribution of 85%. Then the prediction model was built by linear regression, and the decision curve analysis was used to judge the net benefit of LASSO and PCA. In addition, we used two independent cohorts for training (n = 135) and validation (n = 159). We found that the model based on LASSO dimensionality construction had the maximum net benefit (in the training set (AUC [95% confidence interval], 0.857 [0.787–0.912]) and in the validation set (0.834 [0.714–0.918]). The radiomics nomogram combined with clinical risk factors and LASSO features showed a good predictive performance in the training set (0.921 [0.862–0.961]) and validation set (0.912 [0.809–0.97]). Our study indicated that radiomics based on primary rectal cancer could provide a non-invasive way to predict the risk of SLM in clinical practice.

Incorporating atomically dispersed metal species into functionalized metal-organic frameworks (MOFs) can integrate their respective merits for catalysis. A cage-controlled encapsulation and reduction strategy is used to fabricate single Ru atoms and triatomic Ru3 clusters anchored on ZIF-8 (Ru1 @ZIF-8, Ru3 @ZIF-8). The highly efficient and selective catalysis for semi-hydrogenation of alkyne is observed. The excellent activity derives from high atom-efficiency of atomically dispersed Ru active sites and hydrogen enrichment by the ZIF-8 shell. Meanwhile, ZIF-8 shell serves as a novel molecular sieve for olefins to achieve absolute regioselectivity of catalyzing terminal alkynes but not internal alkynes. Moreover, the size-dependent performance between Ru3 @ZIF-8 and Ru1 @ZIF-8 is detected in experiment and understood by quantum-chemical calculations, demonstrating a new and promising approach to optimize catalysts by controlling the number of atoms.

Here, we have developed a cobalt single-atom-site catalyst (Co1/P-NC). Benefiting from the unique properties of single atoms and ingenious support modification by atomic-level heteroatom nitrogen and phosphorus doping, the Co1/P-NC catalyst exhibited high activity and excellent selectivity for selective oxidation of primary alcohols.

Topological materials host fascinating low dimensional gapless states at the boundary. As a prominent example, helical topological edge states (TESs) of two-dimensional topological insulators (2DTIs) and their stacked three-dimensional (3D) equivalent, weak topological insulators (WTIs), have sparked research enthusiasm due to their potential application in the next generation of electronics/spintronics with low dissipation. Here, we propose layered superconducting material CaSn as a WTI with nontrivial Z2 as well as nodal line semimetal protected by crystalline non-symmorphic symmetry. Our systematic angle-resolved photoemission spectroscopy (ARPES) investigation on the electronic structure exhibits excellent agreement with the calculation. Furthermore, scanning tunnelling microscopy/spectroscopy (STM/STS) at the surface step edge shows signatures of the expected TES. These integrated evidences from ARPES, STM/STS measurement and corresponding ab initio calculation strongly support the existence of TES in the non-symmorphic nodal line semimetal CaSn, which may become a versatile material platform to realize multiple exotic electronic states as well as topological superconductivity.

Recently, layered copper chalcogenides ${\mathrm{Cu}}_{2}X$ family $(X=\mathrm{S}, \mathrm{Se}, \mathrm{Te})$ has attracted tremendous research interests due to their high thermoelectric performance, which is partly due to the superionic behavior of mobile Cu ions, making these compounds ``phonon liquids.'' Here, we systematically investigate the electronic structure and its temperature evolution of the less studied single crystal ${\mathrm{Cu}}_{2\ensuremath{-}x}\mathrm{Te}$ by the combination of angle resolved photoemission spectroscopy (ARPES) and scanning tunneling microscope/spectroscopy (STM/STS) experiments. While the band structure of the ${\mathrm{Cu}}_{2\ensuremath{-}x}\mathrm{Te}$ shows agreement with the calculations, we clearly observe a $2\ifmmode\times\else\texttimes\fi{}2$ surface reconstruction from both our low temperature ARPES and STM/STS experiments which survives up to room temperature. Interestingly, our low temperature STM experiments further reveal multiple types of reconstruction patterns, which suggests the origin of the surface reconstruction being the distributed deficiency of liquidlike Cu ions. Our findings reveal the electronic structure and impurity level of ${\mathrm{Cu}}_{2}\mathrm{Te}$, which provides knowledge about its thermoelectric properties from the electronic degree of freedom.

Atomic-level insight into the unique catalytic capability of single-atom catalysts that distinguished from nanometer-sized counterparts is highly desirable for catalyst design and catalysis research. By synthesizing single Pd atoms supported on TiO2 as a catalyst, here we demonstrate a steric hindrance effect of single atoms induced by the unique isolation of single-atom active sites to achieve a remarkable enhancement on catalytic performance in the synthesis of dimethyl carbonate. Experimental results and density functional theory calculations reveal that such steric hindrance effect of single atoms favors the yield of the desired product dimethyl carbonate against further reacting with intermediates to form byproduct, because no extra Pd species around single Pd atoms provide active sites to further adsorb and activate substrates directly. The discovery of such steric hindrance effect is a valuable supplement to single-atom catalysis, and may promote single-atom catalysts to be widely applied in selective catalytic reactions.

Distinguishing cell types and cell states is one of the fundamental questions in single-cell studies. Meanwhile, exploring the lineage relations among cells and finding the path and critical points in the cell fate transition are also of great importance.Existing unsupervised clustering methods and lineage trajectory reconstruction methods often face several challenges such as clustering data of arbitrary shapes, tracking precise trajectories and identifying critical points. Certain adaptive landscape approach1–3, which constructs a pseudo-energy landscape of the dynamical system, may be used to explore such problems. Thus, we propose Markov hierarchical clustering algorithm (MarkovHC), which reconstructs multi-scale pseudo-energy landscape by exploiting underlying metastability structure in an exponentially perturbed Markov chain4. A Markov process describes the random walk of a hypothetically traveling cell in the corresponding pseudo-energy landscape over possible gene expression states. Technically, MarkovHC integrates the tasks of cell classification, trajectory reconstruction, and critical point identification in a single theoretical framework consistent with topological data analysis (TDA)5.In addition to the algorithm development and simulation tests, we also applied MarkovHC to diverse types of real biological data: single-cell RNA-Seq data, cytometry data, and single-cell ATAC-Seq data. Remarkably, when applying to single-cell RNA-Seq data of human ESC derived progenitor cells6, MarkovHC not only could successfully identify known cell types, but also discover new cell types and stages. In addition, when using MarkovHC to analyze single-cell RNA-Seq data of human preimplantation embryos in early development7, the hierarchical structure of the lineage trajectories was faithfully reconstituted. Furthermore, the critical points representing important stage transitions had also been identified by MarkovHC from early gastric cancer data8.In summary, these results demonstrate that MarkovHC is a powerful tool based on rigorous metastability theory to explore hierarchical structures of biological data, to identify a cell sub-population (basin) and a critical point (stage transition), and to track a lineage trajectory (differentiation path).HighlightsMarkovHC explores the topology hierarchy in high-dimensional data.MarkovHC can find clusters (basins) and cores (attractors) of clusters in different scales.The trajectory of state transition (transition paths) and critical points in the process of state transition (critical points) among clusters can be tracked.MarkovHC can be applied on diverse types of single-cell omics data.

Demonstrated here is the correlation between atomic configuration induced electronic density of single-atom Co active sites and oxygen reduction reaction (ORR) performance by combining density-functional theory (DFT) calculations and electrochemical analysis. Guided by DFT calculations, a MOF-derived Co single-atom catalyst with the optimal Co1 -N3 PS active moiety incorporated in a hollow carbon polyhedron (Co1 -N3 PS/HC) was designed and synthesized. Co1 -N3 PS/HC exhibits outstanding alkaline ORR activity with a half-wave potential of 0.920 V and superior ORR kinetics with record-level kinetic current density and an ultralow Tafel slope of 31 mV dec-1 , exceeding that of Pt/C and almost all non-precious ORR electrocatalysts. In acidic media the ORR kinetics of Co1 -N3 PS/HC still surpasses that of Pt/C. This work offers atomic-level insight into the relationship between electronic density of the active site and catalytic properties, promoting rational design of efficient catalysts.

BACKGROUND: Radiomics can be used to determine the prognosis of liver cancer, but it might vary among cancer types. This study aimed to explore the clinicopathological features, radiomics, and survival of patients with hepatocellular carcinoma (HCC), mass-type cholangiocarcinoma (MCC), and combined hepatocellular-cholangiocarcinoma (CHCC). METHODS: This was a retrospective cohort study of patients with primary liver cancer operated at the department of hepatobiliary surgery of the First Affiliated Hospital of Zhejiang University from 07/2013 to 11/2015. All patients underwent preoperative liver enhanced MRI scans and diffusion-weighted imaging (DWI). The radiomics characteristics of DWI and the enhanced equilibrium phase (EP) images were extracted. The mRMR (minimum redundancy maximum relevance) was applied to filter the parameters. RESULTS: There were 44 patients with MCC, 59 with HCC, and 33 with CHCC. Macrovascular invasion, tumor diameter, positive ferritin preoperatively, positive AFP preoperatively, positive CEA preoperatively, Correlation, Inverse Difference Moment, and Cluster Prominence in model A (DWI and clinicopathological parameters) were independently associated with overall survival (OS) (P

The van der Waals ferromagnet $\mathrm{F}{\mathrm{e}}_{3}\mathrm{GeT}{\mathrm{e}}_{2}$ has attracted great research attention recently due to its extraordinary properties. Here, using high-resolution angle-resolved photoemission spectroscopy, we systematically investigate the temperature evolution of the electronic structure of bulk $\mathrm{F}{\mathrm{e}}_{3}\mathrm{GeT}{\mathrm{e}}_{2}$. We observe largely dispersive energy bands with exchange splitting that are in overall agreement with our density-functional theory calculation. Interestingly, the band dispersions barely change upon heating towards the ferromagnetic transition near 225 K, except for the reduction of quasiparticle coherence, which strongly deviates from the itinerant Stoner model. We suggest that the local magnetic moments may play a crucial role in the ferromagnetic ordering and the electronic structure of $\mathrm{F}{\mathrm{e}}_{3}\mathrm{GeT}{\mathrm{e}}_{2}$, which will shed light on the generic understanding of itinerant magnetism in correlated materials.

The solar-driven photocatalytic reduction of CO

A nonlinear train-track-bridge system (TTBS) considering the random track irregularity and mass of train is discussed. Based on the Karhunen–Loéve theory, the track irregularity is expressed and input into the TTBS, and the result of random response is calculated using the point estimation method. Two cases are used to compare and validate the applicability of the proposed method, which show that the proposed method has a high precision and efficiency. Then, taking a 7-span bridge and a high-speed train as an example, the calculation results of random response of the nonlinear and linear wheel-rail model are compared, and the results show that for the bridge and rail response, the nonlinear and linear models are almost the same. Finally, comparing the calculated probability distribution results with the test results, it shows that the method can be applied to the prediction of actual response range.

Inversion asymmetric topological insulator promises great potential to realize many intriguing phenomena such as intrinsic topological [Formula: see text]–[Formula: see text] junctions, pyroelectricity and novel topological magneto-electric effects that require inversion asymmetry. Recently, gapless helical surface Dirac fermions were observed in inversion-asymmetric BiTeCl crystal. However, heavy debate about whether BiTeCl is a topological insulator and controversial experimental results of the electronic structure of BiTeCl exist. In this work, through ab-initio calculations, we discovered that a BiTeCl-dominant BiTeCl/Bi2Te3 heterostructure can give rise to the observed band structures with a single surface Dirac fermion. Interestingly, we further suggest that such a BiTeCl/Bi2Te3 heterostructure could be naturally formed by annealing pure BiTeCl single crystals. Our results not only resolve the discrepancy between the previous experiments on heat treated samples and theoretical investigations, but also point out a pathway to design novel materials with sophisticated properties.

The performance and the cost of electrocatalysts play the two most vital roles in the development and application of energy conversion technologies. Single-atom catalysts (SACs) are recently emerging as a new frontier in catalysis science. With maximum atom-utilization efficiency and unique properties, SACs exhibit great potential for enabling reasonable use of metal resources and achieving atomic economy. However, fabricating SACs and maintaining the metal centers as atomically dispersed sites under synthesis and catalysis conditions are challenging. Here, we highlight and summarize recent advances in wet-chemistry synthetic methods for SACs with special emphasis on how to achieve the stabilization of single metal atoms against migration and agglomeration. Moreover, we summarize and discuss the electrochemical applications of SACs with a focus on the oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), and CO2 reduction reaction (CO2RR). At last, the current issues and the prospects for the development of this field are discussed.

Dynamic response analysis of a nonlinear train-track-bridge system under earthquakes is a time-consuming task. In this paper, a fast computing strategy is proposed to reduce the simulation time by solving the shortcomings of classical time integration algorithms in the computation of the coupled system. The core of the strategy focuses on completely explicit computational processes and unconditional stability. Based on the loosely coupling scheme, the model of the train-track-bridge system is divided into two parts, namely, the train substructure established using multibody dynamics and the track-bridge substructure established using the finite element method. Track-bridge substructure and train substructure are separately integrated by the unconditionally stable explicit algorithm, CQ3, and its degenerate form, respectively. The interaction of the two substructures depends on wheel-rail forces. The track-bridge substructure is further decoupled to describe its nonlinear behavior and to improve the speed of solving algebraic equations. The proposed strategy not only avoids the complex iterative process of the nonlinear train-track-bridge system but also eliminates the limitation of the integration time step caused by the minimum natural period of the track-bridge substructure. This paper first simulates the dynamic response of a train under a sinusoidal displacement excitation and extends the simulation strategy to analyze the vibration of the coupling system under an earthquake. The applicability, efficiency, and accuracy of the strategy are illustrated through three numerical analyses. The strategy proposed in this paper provides a convenient and greatly computationally efficient option for simulating the nonlinear dynamic response of a large-scale train-track-bridge system.

Here we report a novel approach to synthesize atomically dispersed uniform clusters via a cage-separated precursor preselection and pyrolysis strategy. To illustrate this strategy, well-defined Ru3(CO)12 was separated as a precursor by suitable molecular-scale cages of zeolitic imidazolate frameworks (ZIFs). After thermal treatment under confinement in the cages, uniform Ru3 clusters stabilized by nitrogen species (Ru3/CN) were obtained. Importantly, we found that Ru3/CN exhibits excellent catalytic activity (100% conversion), high chemoselectivity (100% for 2-aminobenzaldehyde), and significantly high turnover frequency (TOF) for oxidation of 2-aminobenzyl alcohol. The TOF of Ru3/CN (4320 h–1) is about 23 times higher than that of small-sized (ca. 2.5 nm) Ru particles (TOF = 184 h–1). This striking difference is attributed to a disparity in the interaction between Ru species and adsorbed reactants.