Explore the vast range of titles available.

Electromagnetic (EM) wave absorbing materials play an increasingly important role in modern society for their multi‐functional in military stealth and incoming 5G smart era. Dielectric loss EM wave absorbers and underlying loss mechanism investigation are of great significance to unveil EM wave attenuation behaviors of materials and guide novel dielectric loss materials design. However, current researches focus more on materials synthesis rather than in‐depth mechanism study. Herein, comprehensive views toward dielectric loss mechanisms including interfacial polarization, dipolar polarization, conductive loss, and defect‐induced polarization are provided. Particularly, some misunderstandings and ambiguous concepts for each mechanism are highlighted. Besides, in‐depth dielectric loss study and novel dielectric loss mechanisms are emphasized. Moreover, new dielectric loss mechanism regulation strategies instead of regular components compositing are summarized to provide inspiring thoughts toward simple and effective EM wave attenuation behavior modulation. Electromagnetic wave loss mechanism investigation for dielectric absorbing materials is of great importance to guide the preparation of novel high‐performance absorbers. This review provides comprehensive insights into dielectric loss mechanisms and clarifies some misunderstandings and ambiguous concepts for each mechanism. In‐depth dielectric loss study and novel dielectric loss mechanisms regulation strategies are also highlighted.

Defect engineering is an effective approach to manipulate electromagnetic (EM) parameters and enhance absorption ability, but defect induced dielectric loss dominant mechanism has not been completely clarified. Here the defect induced dielectric loss dominant mechanism in virtue of multi‐shelled spinel hollow sphere for the first time is demonstrated. The unique but identical morphology design as well as suitable composition modulation for serial spinels can exclude the disturbance of EM wave dissipation from dipolar/interfacial polarization and conduction loss. In temperature‐regulated defect in NiCo2O4 serial materials, two kinds of defects, defect in spinel structure and oxygen vacancy are detected. Defect in spinel structure played more profound role on determining materials’ EM wave dissipation than that of oxygen vacancy. When evaluated serial Co‐based materials as absorbers, defect induced polarization loss is responsible for the superior absorption performance of NiCo2O4‐based material due to its more defect sites in spinel structure. It is discovered that electron spin resonance test may be adopted as a novel approach to directly probe EM wave absorption capacities of materials. This work not only provides a strategy to prepare lightweight, efficient EM wave absorber but also illustrates the importance of defect engineering on regulation of materials’ dielectric loss capacity. The importance of defect induced polarization loss in electromagnetic wave absorption is revealed by engineering defect in serial Co‐based multi‐shelled spinel hollow spheres. For the first time, defect in spinel structure and its induced loss mechanism is found to play dominate role over other loss mechanisms. This unique hollow structure also affords lightweight spinel electromagnetic wave absorbing materials.

The extremely weak heterointerface construction of high‐entropy materials (HEM) hinders them being the electromagnetic wave (EMW) absorbers with ideal properties. To address this issue, this study proposes multiphase interfacial engineering and results in a multiphase‐induced interfacial polarization loss in multielement sulfides. Through the selection of atoms with diverse reaction activities, the multiphase interfacial components of CuS (1 0 5), Fe0.5Ni0.5S2 (2 1 0), and CuFe2S3 (2 0 0) are constructed to enhance the interfacial polarization loss in multielement Cu‐based sulfides. Compared with single‐phase high‐entropy Zn‐based sulfides (ZnFeCoNiCr‐S), the multiphase Cu‐based sulfides (CuFeCoNiCr‐S) possess optimized EMW absorption properties (effective absorption bandwidth (EAB) of 6.70 GHz at 2.00 mm) due to the existence of specific interface of CuS (1 0 5)/CuFe2S3 (2 0 0) with proper EM parameters. Furthermore, single‐phase ZnFeCoNiCr‐S into FeNi2S4 (3 1 1)/(Zn, Fe)S (1 1 1) heterointerface through 400 °C heat‐treated is decomposed. The EMW absorption properties are enhanced by strong interfacial polarization (EAB of 4.83 GHz at 1.45 mm). This work reveals the reasons for the limited EMW absorption properties of high‐entropy sulfides and proposes multiphase interface engineering to improve charge accumulation and polarization between specific interfaces, leading to the enhanced EMW absorption properties. This work shows that the weak electron exchange effect induced by high conformational entropy adversely affects microwave absorption. Constructing the heterointerfaces with significantly different work functions in multi‐element sulfides can effectively enhance the phase interface polarization and eliminate these negative effects. This is expected to serve as a new design guideline for microwave absorbers.

Wireless energy-responsive systems provide a foundational platform for powering and operating intelligent devices. However, current electronic systems relying on complex components limit their effective deployment in ambient environment and seamless integration of energy harvesting, storage, sensing, and communication. Here, we disclose a coupling effect of electromagnetic wave absorption and moist-enabled generation on carrier transportation and energy interaction regulated by ionic diode effect. As demonstration, a wireless energy interactive system is established for electromagnetic-moist coupled energy harvesting and signal transmission through highly integrated polyelectrolyte/conjugated conductive polymer bilayer ionic diode films as dynamic energy-switching carriers. The gradient distribution of ions within the films, excited by moist energy, enables the ionic rectification and further endows the films with electromagnetic energy harvesting capability. In turn, the absorbed electromagnetic energy drives the directional migration of charge carriers and internal ionic current. By rationally regulating the electrolyte and dielectric properties of ionic diodes, it becomes feasible to control targeted electric signals and energy outputs under coupled electromagnetic-moist environment. This work is a step towards enabling enhanced smart interactivities for wirelessly driven flexible electronics. Wireless energy-responsive systems are essential for intelligent devices. This study demonstrates an electromagnetic-moist coupling effect for energy harvesting and signal transmission using fabricated ionic diode films, showing improved performance and potential for practical applications.

The lack of a chemical platform with high spatial dimensional diversity, coupled with the elusive multi-scale amorphous physics, significantly hinder advancements in amorphous electromagnetic wave absorption (EWA) materials. Herein, we present a synergistic engineering of phenolic multiple kinetic dynamics and discrete crystallization thermodynamics, to elucidate the origin of the dielectric properties in amorphous carbon and the cascade effect during EWA. Leveraging the scalability of phenolic synthesis, we design dozens of morphologies from the bottom up and combine with in-situ pyrolysis to establish a nanomaterial ecosystem of hundreds of amorphous carbon materials. Based on controlled discrete crystallization, nano-curvature regulation of spatial inversion symmetry-breaking structures, and surface electric field enhancement from multi-shell structures, the multi-scale charge imbalance triggers intense polarization. Both experiments and theories show that each scale is essential, which collectively drives broadband absorption (8.46 GHz) and efficient dissipation (−54.77 dB) of EWA performance. Our work on the amorphous nanostructure platform and the cascade effect can contribute to uncovering the missing pieces in amorphous physics and EWA research. This study presents a phenolic synthesis platform with high spatial dimensional diversity, to elucidate the origin of the dielectric properties in amorphous carbon and the cascade effect during electromagnetic wave absorption.

Texture regulation of metal–organic frameworks (MOFs) is essential for controlling their electromagnetic wave (EMW) absorption properties. This review systematically summarizes the recent advancements in texture regulation strategies for MOFs, including etching and exchange of central ions, etching and exchange of ligands, chemically induced self‐assembly, and MOF‐on‐MOF heterostructure design. Additionally, the EMW absorption mechanisms in approaches based on structure–function dependencies, including nano‐micro topological engineering, defect engineering, interface engineering, and hybrid engineering, are comprehensively explored. Finally, current challenges and future research orientation are proposed. This review aims to provide new perspectives for designing MOF‐derived EMW‐absorption materials to achieve essential breakthroughs in mechanistic investigations in this promising field. A novel review summarizes texture regulation of metal–organic frameworks (MOFs), including etching and exchange of central ions, etching and exchange of ligands, chemically‐induced self‐assembly, and MOF‐on‐MOF heterostructures. Relative optimization engineering toward microwave absorption mechanism is proposed, including nano‐micro topology engineering, defect engineering, interface engineering, and hybrid engineering. A perspective for future development of MOFs derived microwave absorption materials is proposed.

CoFe 2 O 4 has been widely used for electromagnetic wave absorption owing to its high Snoek limit, high anisotropy, and suitable saturation magnetization; however, its inherent shortcomings, including low dielectric loss, high density, and magnetic agglomeration, limit its application as an ideal absorbent. This study investigated a microstructure regulation strategy to mitigate the inherent disadvantages of pristine CoFe 2 O 4 synthesized via a sol–gel auto-combustion method. A series of CoFe 2 O 4 foams (S0.5, S1.0, and S1.5, corresponding to foams with citric acid (CA)-to-Fe(NO 3 ) 3 ·9H 2 O molar ratios of 0.5, 1.0, and 1.5, respectively) with two-dimensional (2D) curved surfaces were obtained through the adjustment of CA-to-Fe 3+ ratio, and the electromagnetic parameters were adjusted through morphology regulation. Owing to the appropriate impedance matching and conductance loss provided by moderate complex permittivity, the effective absorption bandwidth (EAB) of S0.5 was as high as 7.3 GHz, exceeding those of most CoFe 2 O 4 -based absorbents. Moreover, the EAB of S1.5 reached 5.0 GHz (8.9–13.9 GHz), covering most of the X band, owing to the intense polarization provided by lattice defects and the heterogeneous interface. The three-dimensional (3D) foam structure circumvented the high density and magnetic agglomeration issues of CoFe 2 O 4 nanoparticles, and the good conductivity of 2D curved surfaces could effectively elevate the complex permittivity to ameliorate the dielectric loss of pure CoFe 2 O 4 . This study provides a novel idea for the theoretical design and practical production of lightweight and broadband pure ferrites.

Aim Increased atmospheric nitrogen deposition may have profound effects on tree carbon allocation dynamics. However, a comprehensive understanding of how nitrogen (N) enrichment influences carbon (C) allocation across plant functional processes and tree organs in individual trees remains elusive. Location Global forest ecosystems. Time period 1990–2018. Major taxa studied Trees. Methods We compiled data from 75 N addition experiments and conducted a meta‐analysis to evaluate the responses of C source (photosynthesis), sinks (growth and respiration) and storage (non‐structural carbohydrate concentrations) in different tree organs (foliage, above‐ground wood and roots) to N enrichment. Results N enrichment significantly enhanced C supply via photosynthesis (+39.6%, n = 128). C allocation to growth (biomass increment/production) significantly increased in foliage (+15.9%, n = 68) and above‐ground wood (+31.8%, n = 64; bole, branch, stem and/or twig) with increasing N availability, but not in roots, whereas allocation increased in roots via increasing fine root turnover rate (+22.6%, n = 11). N fertilization significantly increased C allocation to respiration in above‐ground wood (+46.6%, n = 12) and roots (+5.5%, n = 57), but not in foliage. N addition decreased non‐structural carbohydrate (NSC) concentrations in foliage (−5.4%, n = 16) and roots (−5.0%, n = 21), but increased NSC in above‐ground wood (+6.1%, n = 22). In addition, N enrichment effects were strongly affected by moderator variables. Main conclusions Our results demonstrate that N addition increased C allocation to growth and respiration more strongly than C allocation to NSC storage, and increased C allocation to above‐ground parts more strongly than to below‐ground parts. Our results are useful for better understanding the response of tree functional processes at organ level to N enrichment. The existing data also reveal that more long‐term experimental studies on mature trees in tropical and boreal forests are urgently needed to provide a basis for forecasting tree responses to N enrichment at the global scale.

Various wireless devices have been widely used in every aspect of life and further lead to the severe electromagnetic waves pollution. Fortunately, researchers have developed microwave absorbing materials which are able to transfer the harmful electromagnetic waves into other energy, such as thermal energy. In recent years, numerous studies on preparing microwave absorbing materials with various components, morphologies and structures have been reported. Metal oxide-related composites are widely used as microwave absorbers due to their excellent electromagnetic properties. The morphology and nanostructure would play a key role on the microwave absorbing performances, which can cause “structural effect”. The ideal microwave absorbing materials should meet following demands: widely effective absorption frequency (fE), thinner thickness (d), light-weight, and strong absorption. In this review, we summarized various common morphologies and structures of metal oxide/metal oxide-based composites, and categorized them from a dimensional perspective. The different microwave absorbing properties and mechanisms are given much attention in detail.

Hydrological models are widely used as simplified, conceptual, mathematical representatives for water resource management. The performance of hydrological modeling is usually challenged by model calibration and uncertainty analysis during modeling exercises. In this study, a multicriteria sequential calibration and uncertainty analysis (MS-CUA) method was proposed to improve the efficiency and performance of hydrological modeling with high reliability. To evaluate the performance and feasibility of the proposed method, two case studies were conducted in comparison with two other methods, sequential uncertainty fitting algorithm (SUFI-2) and generalized likelihood uncertainty estimation (GLUE). The results indicated that the MS-CUA method could quickly locate the highest posterior density regions to improve computational efficiency. The developed method also provided better-calibrated results (e.g., the higher NSE value of 0.91, 0.97, and 0.74) and more balanced uncertainty analysis results (e.g., the largest P/R ratio values of 1.23, 2.15, and 1.00) comparing with other traditional methods for both case studies.