Search

Abstract Despite the prevalent of hexagonal, tetragonal, and triangular pore structures in two-dimensional covalent organic frameworks (2D COFs), the pentagonal pores remain conspicuously absent. We herein present the Cairo pentagonal tessellated COFs, achieved through precisely chosen geometry and metrics of the linkers, resulting in unprecedented mcm topology. In each pentagonal structure, porphyrin units create four uniform sides around 15.5 Å with 90° angles, while tetrabiphenyl unit establish a bottom edge about 11.6 Å with 120° angles, aligning precisely with the criteria of Cairo Pentagon. According to the narrow bandgap and strong near-infrared (NIR) absorbance, as-synthesized COFs exhibit the efficient singlet oxygen (1O2) generation and photothermal conversion, resulting in NIR photothermal combined photodynamic therapy to guide cancer cell apoptosis. Mechanistic studies reveal that the good 1O2 production capability upregulates intracellular lipid peroxidation, leading to glutathione depletion, low expression of glutathione peroxidase 4, and induction of ferroptosis. The implementation of pentagonal Cairo tessellations in this work provides a promising strategy for diversifying COFs with new topologies, along with multimodal NIR phototherapy.

With the continuous advancement of smart greenhouse technologies, digital and information-based environmental monitoring has emerged as a focal point of research. The development of high-performance gas sensors is central to achieving this objective. In recent years, MXene materials have been widely applied in the field of gas sensors due to their excellent ion mobility, favorable hydrophilicity, outstanding electronic conductivity, and unique physicochemical properties. Various MXene heterojunction structures have been synthesized for gas detection. This review aims to summarize the current state of research on Ti3C2Tx-based gas sensors, explore methods for synthesizing different morphologies of Ti3C2Tx heterojunction structures, and evaluate the sensing behaviors of these configurations to fully harness their potential for gas monitoring in greenhouse environments. Additionally, an in-depth analysis of the sensing mechanisms associated with Ti3C2Tx heterojunction structures will be provided, offering theoretical support for future investigations. The findings indicate that Ti3C2Tx-based nanomaterials demonstrate considerable promise as high-performance sensors for gas detection in greenhouse settings. This innovative research not only provides new insights into the development of gas sensor technologies but also serves as an important foundation for the digitization of environmental monitoring.

Abstract Realizing spin transport between heavy metal and two‐dimensional (2D) magnetic materials at high Curie temperature (TC) is crucial to advanced spintronic information storage technology. Here, environmentally stable 2D nonlayered Fe3O4 nanosheets are successfully synthesized using a reproducible process and found that they exhibit vortex magnetic domains at room temperature. A Verwey phase transition temperature (TV) of ≈110 K is identified for ≈3 nm thick nanosheet through Raman characterization and spin Hall device measurement of the Pt/Fe3O4 bilayer. The anisotropic magnetoresistance ratio decreases near TV, while both the spin Hall magnetoresistance ratio and spin mixing conductance (Gr) increase at TV. As the temperature approaches 112 K, the anomalous Hall effect ratio tends to become zero. The maximum Gr reaches ≈5 × 1015 Ω−1m−2 due to the clean and flat interface between Pt and 2D nanosheet. The observed spin transport behavior in Pt/Fe3O4 spin Hall devices indicates that 2D Fe3O4 nanosheets possess potential for high‐power micro spintronic storage devices applications.

Abstract Practical application of lithium–sulfur (Li–S) batteries is severely impeded by the random shuttling of soluble lithium polysulfides (LiPSs), sluggish sulfur redox kinetics, and uncontrollable growth of lithium dendrites, particularly under high sulfur loading and lean electrolyte conditions. Here, nitrogen‐doped bronze‐phase TiO2(B) nanosheets with oxygen vacancies (OVs) grown in situ on MXenes layers (N‐TiO2−x(B)‐MXenes) as multifunctional interlayers are designed. The N‐TiO2−x(B)‐MXenes show reduced bandgap of 1.10 eV and high LiPSs adsorption‐conversion‐nucleation‐decomposition efficiency, leading to remarkably enhanced sulfur redox kinetics. Moreover, they also have lithiophilic nature that can effectively suppress dendrites growth. The cell based on the N‐TiO2−x(B)‐MXenes interlayer under sulfur loading of 2.5 mg cm−2 delivers superior cycling performance with a high specific capacity of 690.7 mAh g−1 over 600 cycles at 1.0 C. It still has a notable areal capacity of 6.15 mAh cm−2 after 50 cycles even under a high sulfur loading of 7.2 mg cm−2 and a low electrolyte‐to‐sulfur (E/S) ratio of 6.4 µL mg−1. The Li‐symmetrical battery with the N‐TiO2−x(B)‐MXenes interlayer showcases a low over‐potential fluctuation with 21.0 mV throughout continuous lithium plating/stripping for 1000 h. This work offers valuable insights into the manipulation of defects and heterostructures to achieve high‐energy Li–S batteries.

Abstract 2D magnetic materials hold substantial promise in information storage and neuromorphic device applications. However, achieving a 2D material with high Curie temperature (TC), environmental stability, and multi‐level magnetic states remains a challenge. This is particularly relevant for spintronic devices, which require multi‐level resistance states to enhance memory density and fulfil low power consumption and multi‐functionality. Here, the synthesis of 2D non‐layered triangular and hexagonal magnetite (Fe3O4) nanosheets are proposed with high TC and environmental stability, and demonstrate that the ultrathin triangular nanosheets show broad antiphase boundaries (bAPBs) and sharp antiphase boundaries (sAPBs), which induce multiple spin precession modes and multi‐level resistance. Conversely, the hexagonal nanosheets display slip bands with sAPBs associated with pinning effects, resulting in magnetic‐field‐driven spin texture reversal reminiscent of “0” and “1” switching signals. In support of the micromagnetic simulation, direct explanation is offer to the variation in multi‐level resistance under a microwave field, which is ascribed to the multi‐spin texture magnetization structure and the randomly distributed APBs within the material. These novel 2D magnetite nanosheets with unique spin textures and spin dynamics provide an exciting platform for constructing real multi‐level storage devices catering to emerging information storage and neuromorphic computing requirements.

Abstract Advanced lithium‐ion batteries (LIBs) are crucial to portable devices and electric vehicles. However, it is still challenging to further develop the current anodic materials such as graphite due to the intrinsic limited capacity and sluggish Li‐ion diffusion. Indium nitride (InN), which is a new type of anodic material with low redox potential (

Flexible thermoelectric generators (FTEGs) offer a promising solution for powering wearable electronics, while their practical applications are mainly obstructed by the moderate properties of flexible thermoelectric (TE) materials. Here, flexible Ag2Se nanowire (NW)/methyl cellulose (MC) composite films were developed via facile screen-printing technology combined with cold pressing and annealing treatment, and a highest power factor of 1,641.58 μW m−1 K−2 at 360 K was achieved. The reasons for the high TE performance of the Ag2Se NW/MC composite films were because, after the annealing treatment, the Ag2Se NWs were sintered to form conductive network structures, the crystallinity of Ag2Se was markedly enhanced, and the content of insulating phase MC in the composite film was decreased. The Ag2Se NW/MC composite film held appreciable flexibility, as its room-temperature power factor (1,312.08 μW m−1 K−2) can retain ~93% after bending for 1,000 cycles at a radius of 4 mm. Furthermore, the assembled FTEG consisting of 4 strips can generate a maximal power density of 3.51 W m−2 at a temperature difference of 14.1 K. Our results open an effective and large-scale strategy for fabricating high-performance flexible TE materials and energy-harvesting devices.

Introduction: Computer-aided design has become an important tool to develop novel pesticides based on natural lead compounds. Tenuazonic acid (TeA), a typical representative of the natural tetramic acid family, was patented as a potential bioherbicide. However, its herbicidal efficacy is still not up to the ideal standard of commercial products. Objectives: We aim to find new TeA’s derivatives with improved potency. Methods: Molecular docking was used to build ligand-acceptor interaction models, design and screen new derivatives. Phytotoxicity, oxygen evolution rate, chlorophyll fluorescence and herbicidal efficacy were determined to estimate biological activity of compounds. Results: With the aid of a constructed molecular model of natural lead molecule TeA binding to the QB site in Arabidopsis D1 protein, a series of derivatives differing in the alkyl side chain were designed and ranked according to free energies. All compounds are stabilized by hydrogen bonding interactions between their carbonyl oxygen O2 and D1-Gly256 residue; moreover, hydrogen bond distance is the most important factor for maintaining high binding affinity. Among 54 newly designed derivatives, D6, D13 and D27 with better affinities than TeA were screened out and synthesized to evaluate their photosynthetic inhibitory activity and herbicidal efficacy. Analysis of structure-activity relationship indicated that D6 and D13 with sec-pentyl and sec-hexyl side chains, respectively, were about twice more inhibitory of PSII activity and effective as herbicide than TeA with a sec-butyl side chain. Conclusion: D6 and D13 are promising compounds to develop TeA-derived novel PSII herbicides with superior performance.

The detection of dissolved gases in oil is an important method for the analysis of transformer fault diagnosis. In this article, the potential-doped structure of the Ag3 cluster on the HfSe2 monolayer and adsorption behavior of CO and C2H4 upon Ag3–HfSe2 were studied theoretically. Herein, the binding energy, adsorption energy, band structure, density of state (DOS), partial density of state (PDOS), Mulliken charge analysis, and frontier molecular orbital were investigated. The results showed that the adsorption effect on C2H4 is stronger than that on CO. The electrical sensitivity and anti-interference were studied based on the bandgap and adsorption energy of gases. In particular, there is an increase of 55.49% in the electrical sensitivity of C2H4 after the adsorption. Compared to the adsorption energy of different gases, it was found that only the adsorption of the C2H4 system is chemisorption, while that of the others is physisorption. It illustrates the great anti-interference in the detection of C2H4. Therefore, the study explored the potential of HfSe2-modified materials for sensing and detecting CO and C2H4 to estimate the working state of power transformers.

Here, the authors synthesize a variety of ultra-thin III–V single crystals, ranging from ultra-narrow to wide bandgap semiconductors, through enhancing the interfacial interaction between the III–V crystals and the growth substrates.

The ultrathin oxide nanosheets obtained through previous approaches usually exhibit amorphism or polycrystallinity, which limit their properties towards electronic devices. Here, the authors synthesize ultrathin antimony oxide single crystals with high dielectric constant (~100) and large breakdown voltage (~5.7 GV m−1).

Hydrogen sulfide (H2S) and sulfur dioxide (SO2) are two typical decomposition byproducts of sulfur hexafluoride (SF6), commonly used as an insulating medium in electrical equipment; for instance, in gas circuit breakers and gas insulated switchgears. In our work, fiber-like p-CuO/n-ZnO heterojunction gas sensing materials were successfully prepared via the electrospinning method to detect the SF6 decomposition byproducts, H2S and SO2 gases. The sensing results demonstrated that p-CuO/n-ZnO nanofiber sensors have good sensing performance with respect to H2S and SO2. It is noteworthy that this fiber-like p-CuO/n-ZnO heterojunction sensor exhibits higher and faster response–recovery time to H2S and SO2. The enhanced sensor performances can probably be attributed to the sulfuration–desulfuration reaction between H2S and the sensing materials. Moreover, the gas sensor exhibited a high response to the low exposure of H2S and SO2 gas (below 5 ppm). Towards the end of the paper, the gas sensing mechanism of the prepared p-CuO/n-ZnO heterojunction sensors to SO2 and H2S is discussed carefully. Calculations based on first principles were carried out for Cu/ZnO to construct adsorption models for the adsorption of SO2 and H2S gas molecules. Information on adsorption energy, density of states, energy gap values and charge density were calculated and compared to explain the gas-sensitive mechanism of ZnO on SO2 and H2S gases.

Taking Yingzigou Bridge of Dezhou-Dajiawa railway as the engineering background, the three-dimensional fluid-solid coupling models of pile group caps were established on the basis of five-stage field monitoring data of the settlement and groundwater level drop by using FLAC3D software. On the basis of the field monitoring data checking, the variation of axial force and skin friction of piles at different positions under the condition of water level drop was simulated. The results show that with the underground water level dropped, the axial force of pile along the shaft increased first and then decreased. The cross section of maximum axial force moved down constantly. In the same ground water levels drop, the distance between the maximum axial force and neutral point of each pile and the top of the pile was corner pile > side pile> near borehole center pile > center pile. The size of the pile axial force and negative skin friction resistance was corner pile > side pile> near borehole center pile > center pile. The upper part of the pile was subjected to negative skin friction resistance. The skin friction resistance of each pile along the shaft increased first and then decreased. The lower part of the pile was subjected to positive skin friction resistance. The skin friction resistance of each pile along the shaft increased. The location of the maximum negative friction resistance was about 10m distance from the top of the pile. The maximum negative friction resistance of corner pile was -36.5kPa. The distance of neutral point of center pile from the top was 35.2m. The neutral point of each pile was in accordance with the position of the maximum axial force of the pile. A reliable basis was provided for high-speed railway survey and design and the prevention and control of land subsidence along the railway.

Excessive ethanol gas is a huge safety hazard, and people will experience extreme discomfort after inhalation, so efficient ethanol sensors are of great importance. This article reports on ethanol gas sensors that use NiO hollow spheres assembled from nanoparticles, nanoneedles, and nanosheets prepared by the hydrothermal method. All of the samples were characterized for performance evaluation. The sensors based on the NiO hollow spheres showed a good response to ethanol, and the hollow spheres assembled from nanosheets (NiO-S) obtained the best ethanol gas-sensing performance. NiO-S provided a larger response value (38.4) at 350 °C to 200 ppm ethanol, and it had good stability and reproducibility. The nanosheet structure and the fluffy surface of NiO-S obtained the largest specific surface area (55.20 m2/g), and this structure was beneficial for the sensor to adsorb more gas molecules in an ethanol atmosphere. In addition, the excellent sensing performance could ascribe to the larger Ni3+/Ni2+ of NiO-S, which achieved better electronic properties. Furthermore, in terms of commercial production, the template-free preparation of NiO-S eliminated one step, saving time and cost. Therefore, the sensors based on NiO-S will serve as candidates for ethanol sensing.

Nanoscale precipitations in deformed dilute alloying Mg-Zn-RE alloys usually play critical positive roles in mechanical properties, while characterizing them still poses a significant challenge due to their small size and low volume fraction. Here, we conduct a systematic structural analysis of the nanoscale secondary phase particles, including W phase, a small amount of I phase and a handful of Mg3Gd phase, in hot deformed dilute alloying Mg-Zn-Gd alloy by combining atomic-resolution transmission electron microscopy with first-principles calculations. The investigation of atomic structure of nanoscale W phase reveals that the stoichiometric composition of W phase is determined by the quantity of Mg atoms which are replaced by Zn at certain positions. Furthermore, nanoscale W phase, I phase and Mg3Gd phase particles could exhibit certain orientation relationships and coherent or semi-coherent interface with Mg matrix, which contributes to atomic bonding at their interfaces. We also identify a phase transition from Mg3Gd phase to W phase, which is further supported by first-principles calculations showing that Mg3Zn3Gd2 phase is energetically more favorable than Mg3Gd phase. The phase transition between W phase and I phase could also take place during hot deformation and is reversible by absorbing or releasing Zn atoms at the interfacial region.

We prepare a new type of patented biodegradable biomedical Mg–Nd–Zn–Zr (JDBM) alloy system and impose double continuously extrusion (DCE) processing. The lowest processing temperature is 250 °C for JDBM-2.1Nd and 310 °C for JDBM-2.8Nd, which increases with the Nd concentration. The highest yield strength of 541 MPa is achieved in JDBM-2.1 Nd samples when extruded at 250 °C and the elongation is about 3.7%. Moreover, the alloy with a lower alloying element content can reach a higher yield strength while that with a higher alloying element content can reach a larger elongation after DCE processing. However, when extruded under the same conditions, the alloy with a higher alloying contents exhibits better tensile properties. Keywords: Magnesium alloys, Microstructure, Mechanical properties, Double continuously extrusion

Mg-Zn-RE alloys reinforced with quasicrystals have been investigated extensively because they show excellent balance in mechanical properties. Here, we perform deformation and annealing for Mg-1.50Zn-0.25Gd (at.%) alloy at various temperatures, aimed to gain nanoscale precipitates. We find that after the room-temperature compression, the non-basal dislocation, stacking fault and twining are identified in the as-deformed samples, offering clear evidence that these deformation mechanisms can accommodate room-temperature deformation. We also perform systematic transmission electron microscopy observations of the precipitates in both the as-deformed and as-annealed samples. The results identify the formation of a large amount of secondary-phase precipitates, I-phase and MgZn2, when annealed at 200 °C, and precipitation of a small amount of W-phase when annealed at 400 °C. Keywords: Mg alloys, Quasicrystal, Deformation, Annealing, Precipitation

In order to evaluate the pipeline drainage capacity and urban flood risk objectively, urban storm water risk analysis modeling system (USRAMS) is developed based on EPA SWMM and ArcEngine combined with the principle of equal flow time-line method and water balance. The principle and function of USRAMS and the method of assessing pipeline drainage capacity and urban flood risk with USRAMS are described, and the suitability of USRAMS is verified. Taking Cangzhou as an example, USRAMS is used to assess the pipeline drainage capacity and urban flood risk, and the position of bottleneck pipe and the waterlogging risk distribution are expressed in thematic map accurately and directly. The facts show that USRAMS only needs two parameters, namely the runoff coefficient and the catchment time, and adapts to the current situation in china better; two-dimensional earth surface waterlogging simulation adopts hydrologic budget theory, so its calculation is stable and fast. The results of USRAMS may provide reference for urban waterlogging prevention and control and the planning and reforming of stormwater pipe network system.

Abstract Twin boundaries (TBs) have been observed in and introduced into nonmetallic materials in recent years, which brought new concepts for the design of new structural materials. However, the roles of TB on the mechanical properties and strengthening/softening of transition metal nitrides remain unclear. To investigate the TB effects and the in-plane anisotropy, nanoindentations on VN (111) films with and without TB were simulated with molecular dynamics, in which a cylindrical indenter was used, and its longitudinal axis were assigned along and , respectively. We found that the effect of the indenter orientation is insignificant in the elastic stage, but significant in the following inelastic deformation. Different deformation mechanisms can be found for inelastic deformation, such as twinning and dislocation glide. The migration of TB can be observed, which may release the internal stress, resulting in softening; while the dislocation locking and pileup at TB can enhance the strength. We also found that the strengthening/softening induced by TB depends on the deformation mechanisms induced by indenter directions.

Magnetic semiconductors provide control of spin states in addition to charge states realized in conventional semiconductors, yet currently limited to weak magnetism at low temperature. Liuet al. introduce oxygen into a ferromagnetic metallic glass, resulting in a Curie temperature above 600 K.

Abstract Room‐temperature magnetoelectric (ME) coupling is developed in artificial multilayers and nanocomposites composed of magnetostrictive and electrostrictive materials. While the coupling mechanisms and strengths in multilayers are widely studied, they are largely unexplored in vertically aligned nanocomposites (VANs), even though theory has predicted that VANs exhibit much larger ME coupling coefficients than multilayer structures. Here, strong transverse and longitudinal ME coupling in epitaxial BaTiO3:CoFe2O4 VANs measured by both optical second harmonic generation and piezoresponse force microscopy under magnetic fields is reported. Phase field simulations have shown that the ME coupling strength strongly depends on the vertical interfacial area which is ultimately controlled by pillar size. The ME coupling in VANs is determined by the competition between the vertical interface coupling effect and the bulk volume conservation effect. The revealed mechanisms shed light on the physical insights of vertical interface coupling in VANs in general, which can be applied to a variety of nanocomposites with different functionalities beyond the studied ME coupling effect.

To obtain the influence mechanism of epoxy resin content, curing time, and other external factors on the compressive strength and seawater corrosion resistance of geopolymer, the NaOH and Na2SiO3 were used as activators; the effect of epoxy resin concentration on the corrosion resistance of metakaolin-based geopolymer was investigated by experiments. The mechanism of epoxy resin concentration affecting the polymerization process and the properties of geopolymer was analyzed by X-ray diffraction, scanning electron microscopy-energy spectrum, and Fourier transform infrared spectroscopy. It was shown that the epoxy resin slowed down the polymerization. The presence of epoxy resin had a beneficial effect on compact structure. Furthermore, compared with the noncorrosive specimen, mixed with 30% specimen’s average compressive strength increased by 4.77MPa and 4.24MPa after curing for 1d and 3d and soaking for 56d.

Abstract Understanding classical and nonclassical mechanisms of crystal nucleation and growth at the atomic scale is of great interest to scientists in many disciplines. However, fulfilling direct atomic‐scale observation still poses a significant challenge. Here, by taking a thin amorphous bismuth (Bi) metal nanosheet as a model system, direct atomic resolution of the crystal nucleation and growth initiated from an amorphous state of Bi metal under electron beam inside an aberration‐corrected transmission electron microscope is provided. It is shown that the crystal nucleation and growth in the phase transformation of Bi metal from amorphous to crystalline structure takes place via the particle‐mediated nonclassical mechanism instead of the classical atom‐mediated mechanism. The dimension of the smaller particles in two contacted nanoparticles and their mutual orientation relationship are critical to governing several coalescence pathways: total rearrangement pathway, grain boundary migration‐dominated pathway, and surface migration‐dominated pathway. Sequential strain analyses imply that migration of the grain boundary is driven by the strain difference in two Bi nanocrystals and the coalescence of nanocrystals is a defect reduction process. The findings may provide useful information to clarify the nanocrystal growth mechanisms of other materials on the atomic scale.

Abstract Aqueous sodium‐ion battery of low cost, inherent safety, and environmental benignity holds substantial promise for new‐generation energy storage applications. However, the narrow potential window of water and the enlarged ionic radius because of hydration restrict the selection of electrode materials used in the aqueous electrolyte. Here, inspired by the efficient redox reaction of biomolecules during cellular energy metabolism, a proof of concept is proposed that the redox‐active biomolecule alizarin can act as a novel electrode material for the aqueous sodium‐ion battery. It is demonstrated that the specific capacity of the self‐assembled alizarin nanowires can reach as high as 233.1 mA h g−1, surpassing the majority of anodes ever utilized in the aqueous sodium‐ion batteries. Paired with biocompatible and biodegradable polypyrrole, this full battery system shows excellent sodium storage ability and flexibility, indicating its potential applications in wearable electronics and biointegrated devices. It is also shown that the electrochemical properties of electrodes can be tailored by manipulating naturally occurring 9,10‐anthroquinones with various substituent groups, which broadens application prospect of biomolecules in aqueous sodium‐ion batteries.

We report the microstructure and gas-sensing properties of a nonequilibrium TiO2-SnO2 solid solution prepared by the sol-gel method. In particular, we focus on the effect of Cd doping on the sensing behavior of the TiO2-SnO2 sensor. Of all volatile organic compound gases examined, the sensor with Cd doping exhibits exclusive selectivity as well as high sensitivity to formaldehyde, a main harmful indoor gas. The key gas-sensing quantities, maximum sensitivity, optimal working temperature, and response and recovery time, are found to meet the basic industrial needs. This makes the Cd-doped TiO2-SnO2 composite a promising sensor material for detecting the formaldehyde gas.