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Fluorescent carbon dots (CDs) have emerged as fantastic luminescent nanomaterials with significant potentials on account of their unique photoluminescence properties, high stability, and low toxicity. The application of CDs in electroluminescent light‐emitting diodes (LEDs) have aroused much interest in recent years. Herein, the state‐of‐the‐art advances of CD‐based electroluminescent LEDs are summarized, in which CDs act as active emission layer and interface transport layer materials is discussed and highlighted. Besides, the device structure of CD‐based LEDs and preparation methods of CDs are also introduced. Furthermore, the opportunities and challenges for achieving high performance CD‐based electroluminescent LED devices are presented. This review article is expected to stimulate more unprecedented achievements derived from CDs and CD‐based electroluminescent LEDs, thus further promoting their practical applications in future solid‐state lighting and flat‐panel displays. The application of fluorescent carbon dots (CDs) in electroluminescent light‐emitting diodes (LEDs) have attracted tremendous attention within the last few years. Recent advances concerning CD‐based LEDs are systematically summarized, with an emphasis on the employment of CDs as active emission layer and interface transport layer. Additionally, opportunities and challenges for future achieving high performance CD‐based electroluminescent LED devices are discussed.

Based on the significant geometric nonlinearity associated with large deformations in beams, this paper presents the design of a buckling-type quasi-zero stiffness (BQZS) isolator using slender beams with positive and negative stiffness. This design achieves a characteristic output of nonlinear load-bearing combined with linear stiffness. The elliptic integral method is employed to solve the mechanical equations of the large deformation beams. Through numerical simulations and theoretical calculations, the mechanical properties of the large deformation beams are obtained. A prototype was designed for validation, and its manufacturing and experimental studies are presented. The results demonstrate that the designed BQZS isolator effectively attenuates the system’s vibration response, achieving a 95% reduction at 5 Hz vibration excitation. Additionally, the natural frequency of the isolator with BQZS is less than 1 Hz.

The aerospace community widely uses difficult-to-cut materials, such as titanium alloys, high-temperature alloys, metal/ceramic/polymer matrix composites, hard and brittle materials, and geometrically complex components, such as thin-walled structures, microchannels, and complex surfaces. Mechanical machining is the main material removal process for the vast majority of aerospace components. However, many problems exist, including severe and rapid tool wear, low machining efficiency, and poor surface integrity. Nontraditional energy-assisted mechanical machining is a hybrid process that uses nontraditional energies (vibration, laser, electricity, etc) to improve the machinability of local materials and decrease the burden of mechanical machining. This provides a feasible and promising method to improve the material removal rate and surface quality, reduce process forces, and prolong tool life. However, systematic reviews of this technology are lacking with respect to the current research status and development direction. This paper reviews the recent progress in the nontraditional energy-assisted mechanical machining of difficult-to-cut materials and components in the aerospace community. In addition, this paper focuses on the processing principles, material responses under nontraditional energy, resultant forces and temperatures, material removal mechanisms, and applications of these processes, including vibration-, laser-, electric-, magnetic-, chemical-, advanced coolant-, and hybrid nontraditional energy-assisted mechanical machining. Finally, a comprehensive summary of the principles, advantages, and limitations of each hybrid process is provided, and future perspectives on forward design, device development, and sustainability of nontraditional energy-assisted mechanical machining processes are discussed. A topical review of nontraditional energy-assisted mechanical machining is introduced. The advantages and limitations of each hybrid machining process are addressed. Perspectives on forward design, device development, and sustainability are discussed.

HighlightsA novel FeCoNi carbon fiber (FeCoNi/CF) is obtained through an improved electrospinning technology, which greatly endows the fiber with strong magnetic property.The FeCoNi/CF exhibits an enhanced electromagnetic loss capability due to the construction of one-dimensional magnetic FeCoNi alloy.The designed one-dimensional FeCoNi/CF exhibits excellent performance, with a broad effective absorption band of 1.3 GHz in the low-frequency electromagnetic field at an ultrathin thickness of 2 mm, which provides a great potential for practical application in the future.Rational designing of one-dimensional (1D) magnetic alloy to facilitate electromagnetic (EM) wave attenuation capability in low-frequency (2–6 GHz) microwave absorption field is highly desired but remains a significant challenge. In this study, a composite EM wave absorber made of a FeCoNi medium-entropy alloy embedded in a 1D carbon matrix framework is rationally designed through an improved electrospinning method. The 1D-shaped FeCoNi alloy embedded composite demonstrates the high-density and continuous magnetic network using off-axis electronic holography technique, indicating the excellent magnetic loss ability under an external EM field. Then, the in-depth analysis shows that many factors, including 1D anisotropy and intrinsic physical features of the magnetic medium-entropy alloy, primarily contribute to the enhanced EM wave absorption performance. Therefore, the fabricated EM wave absorber shows an increasing effective absorption band of 1.3 GHz in the low-frequency electromagnetic field at an ultrathin thickness of 2 mm. Thus, this study opens up a new method for the design and preparation of high-performance 1D magnetic EM absorbers.

Administrative division is an important resource to promote the urbanization process and economic growth in China. As an important way of urban spatial expansion, the effect of the removal of counties (county-level cities) into municipal districts(RCD) on economic growth remains to be empirically tested. In this paper, the panel data at the county level from 1998 to 2016 and the differential method were selected to study this problem. The results show that, during the study period, the RCD significantly promoted the economic growth of Chinese cities. The effect of removing counties (county-level cities) from large cities and megacities to set up districts is obviously better than that of small and medium-sized cities. In small and medium-sized cities with small urban permanent population, the RCD has obvious negative impact on economic development. The effect of county (county-level city) reform in eastern and central regions is more significant, while the effect of policy in western and northeast regions is not significant. When the development intensity of the municipal district is between 15%-20%, the effect of the RCD is relatively good, and the administrative division adjustment of the municipal district has a certain optimal window period.

Integrating 2D (semi)metals and semiconductors into atomic-scale Schottky heterojunctions offers a promising pathway for achieving robust charge separation, crucial for microwave absorbers, electromagnetic interference shielding materials, electrocatalysts, photocatalysts, etc. However, conventional bottom-up assembly approaches often encounter challenges of severe agglomeration of 2D components and non-basal contacts due to lattice mismatch, resulting in a suboptimal interfacial density and insufficient charge separation. This study introduces a top-down approach involving the thermal deintercalation of graphene/alkylamine superlattices, leading to the in-situ formation of Schottky heterojunctions between the thermally reduced p-type rGO-alkylamine superlattice phase and entirely deintercalated semimetallic rGO phase (rGO denotes reduced graphene oxide), which can be flexibly tuned by the length of the alkylamines. A spatial network of 2D/2D vertical/lateral Schottky heterojunctions is thus formed with high interfacial density, greatly facilitating charge separation, and thereby strengthening polarization loss while reducing conduction loss. This ensures steady permittivity in the Ku band, maintaining strong absorption under small oblique incidence. Accordingly, a record-high simulated far-field bistatic radar cross-section reduction of 72.68 dB at 1° is attained along with diversified adaptive multifunctionality. This paper provides a groundbreaking avenue realizing spatially distributed atomic-scale 2D/2D Schottky heterojunctions in 2D materials, promoting various related functional materials. Dense atomic-scale 2D/2D Schottky heterojunctions are achieved in the graphene-based superlattice nanocomposites by controlled deintercalation, largely facilitating spatial charge separation that optimizes their microwave-absorbing performance.

HighlightsThe successful fabrication of layered foam/film structure via the crystal melting temperature mismatch for two grades of PVDF resin in a batch foaming process.Developing the heterostructure interfaces between SiC nanowires and MXene (Ti3C2Tx) nanosheets.Achieving efficient electromagnetic interference shielding effectiveness with ultralow reflectivity.Lightweight, high-efficiency and low reflection electromagnetic interference (EMI) shielding polymer composites are greatly desired for addressing the challenge of ever-increasing electromagnetic pollution. Lightweight layered foam/film PVDF nanocomposites with efficient EMI shielding effectiveness and ultralow reflection power were fabricated by physical foaming. The unique layered foam/film structure was composed of PVDF/SiCnw/MXene (Ti3C2Tx) composite foam as absorption layer and highly conductive PVDF/MWCNT/GnPs composite film as a reflection layer. The foam layer with numerous heterogeneous interfaces developed between the SiC nanowires (SiCnw) and 2D MXene nanosheets imparted superior EM wave attenuation capability. Furthermore, the microcellular structure effectively tuned the impedance matching and prolonged the wave propagating path by internal scattering and multiple reflections. Meanwhile, the highly conductive PVDF/MWCNT/GnPs composite (~ 220 S m−1) exhibited superior reflectivity (R) of 0.95. The tailored structure in the layered foam/film PVDF nanocomposite exhibited an EMI SE of 32.6 dB and a low reflection bandwidth of 4 GHz (R < 0.1) over the Ku-band (12.4 − 18.0 GHz) at a thickness of 1.95 mm. A peak SER of 3.1 × 10–4 dB was obtained which corresponds to only 0.0022% reflection efficiency. In consequence, this study introduces a feasible approach to develop lightweight, high-efficiency EMI shielding materials with ultralow reflection for emerging applications.

Harvesting largely ignored and wasted electromagnetic (EM) energy released by electronic devices and converting it into direct current (DC) electricity is an attractive strategy not only to reduce EM pollution but also address the ever-increasing energy crisis. Here we report the synthesis of nanoparticle-templated graphene with monodisperse and staggered circular nanopores enabling an EM–heat–DC conversion pathway. We experimentally and theoretically demonstrate that this staggered nanoporous structure alters graphene’s electronic and phononic properties by synergistically manipulating its intralayer nanostructures and interlayer interactions. The staggered circular nanoporous graphene exhibits an anomalous combination of properties, which lead to an efficient absorption and conversion of EM waves into heat and in turn an output of DC electricity through the thermoelectric effect. Overall, our results advance the fundamental understanding of the structure–property relationships of ordered nanoporous graphene, providing an effective strategy to reduce EM pollution and generate electric energy. The electromagnetic (EM) energy released by electronic devices in the environment is largely wasted and contributes to EM pollution. Here, the authors report the synthesis of staggered circular nanoporous graphene enabling the absorption and conversion of EM waves into electricity via the thermoelectric effect.

The motion of a single active particle in one dimension with quenched disorder under the external force is investigated. Within the tailored parameter range, anomalous diffusion that displays weak ergodicity breaking is observed, i.e., non-ergodic subdiffusion and non-ergodic superdiffusion. This non-ergodic anomalous diffusion is analyzed through the time-dependent probability distributions of the particle’s velocities and positions. Its origin is attributed to the relative weights of the locked state (predominant in the subdiffusion state) and running state (predominant in the superdiffusion state). These results may contribute to understanding the dynamical behavior of self-propelled particles in nature and the extraordinary response of nonlinear dynamics to the externally biased force.

Deep-blue perovskite light-emitting diodes (PeLEDs) based on reduced-dimensional perovskites (RDPs) still face a few challenges including severe trap-assisted nonradiative recombination, sluggish exciton transfer, and undesirable bathochromic shift of the electroluminescence spectra, impeding the realization of high-performance PeLEDs. Herein, an in situ chlorination (isCl) post-treatment strategy was employed to regulate phase reconstruction and renovate multiple defects of RDPs, leading to superior carrier cooling of 0.88 ps, extraordinary exciton binding energy of 122.53 meV, and higher photoluminescence quantum yield of 60.9% for RDP films with deep-blue emission at 450 nm. The phase regulation is accomplished via fluorine-derived hydrogen bonds that suppress the formation of small- n phases. Multiple defects, including halide vacancies (shallow-state defects) and lead-chloride antisite defects (deep-state defects), are renovated via C=O coordination and hydroxy-group-derived hydrogen bonds. Consequently, deep-blue PeLEDs with a record maximum external quantum efficiency of 6.17% and stable electroluminescence at 454 nm were demonstrated, representing the best-performing deep-blue PeLEDs. In situ chlorination strategy was proposed to renovate multiple defects along with reconstruction of phases in RDPs for efficient and spectrally stable deep-blue PeLEDs with a record EQE of 6.17%.