The intricate charge–discharge reactions and bad conductivity nature of sulfur determine the extreme importance of cathode engineering for Li–S batteries. Herein, spinel ZnCo2O4 porous ...particles@N‐doped reduced graphene oxide (ZnCo2O4@N‐RGO) are prepared via the combined procedures of refluxing and hydrothermal treatment, consisting of interconnected uniform ZnCo2O4 nanocubes with an average size of 5 nm anchored on graphene nanosheets. The as‐obtained composite can act as an inimitable cathode scaffold to suppress the shuttling of polysulfides by chemical confinement of ZnCo2O4 and N‐RGO for the first time, as demonstrated by the adsorption energy of ZnCo2O4 to Li2S4 via the strong chemical bonding between Zn or Co and S. The RGO nanosheets with a relatively high specific surface area provide a good conductive network and structural stability. The introduction of doped N atoms and numerous ZnCo2O4 porous nanoparticles can inhibit the transfer of lithium polysulfides between the cathode and anode. Due to the unique structural and compositional features, the as‐obtained hybrid materials with the high sulfur loading of 71% and even 82% still deliver high specific capacity, good rate capability, and enhanced cycling stability with exceptionally high initial Coulombic efficiency, which displays a high utilization of sulfur.
A unique ZnCo2O4 porous particles@N‐doped reduced graphene oxide (ZnCo2O4@N‐RGO) hybrid is composed of interconnected spinel ZnCo2O4 nanocubes anchored on graphene nanosheets. Due to the advantages of the ZnCo2O4@N‐RGO hybrid with a high electrical conductivity and strong immobilization/blocking ability for polysulfides, the ZnCo2O4@N‐RGO‐based electrode displays high sulfur utilization, long cycling life, and high rate performance in Li–S batteries.
The present study investigated the effects of L1-L2 congruency, collocation type, and restriction on L2 collocational processing. Advanced Chinese learners of English and native English-speaking ...controls performed an online acceptability judgment task to investigate how advanced L2 learners processed congruent (sharing the same meaning and structure in L1 language) collocations and English-only (not equivalent in L1 construction) collocations with the same node (right) word and a different collocate (left). The experimental materials included verb-noun (VN), adjective-noun (AN) collocations, free (less fixed), and restricted (more fixed) collocations chosen from BNC. The results revealed that (i) The non-native speakers were sensitive to L1-L2 congruency, but the native speakers were not. (ii) The native speakers were sensitive to collocation restriction, whereas the non-native speakers were not. These results lend initial support to the mapping hypothesis and open choice principle of L2 collocational processing for Chinese English learners.
A gallium arsenide (GaAs)-based millimeter-wave broadband bandpass filter (BPF) is proposed based on slotted half-mode substrate integrated waveguide (HMSIW) spoof surface plasmon polaritons (SSPPs). ...The center frequency and bandwidth of this SSPP-based on-chip BPF can be easily controlled by tuning the geometry dimensions of the SSPP unit cell, which is attributed to its unique dispersion characteristics. For demonstration, a prototype of the proposed BPF is fabricated and experimentally characterized, with good agreement between the simulated and measured results. Due to the ability of the strong electric field confinement, the proposed on-chip SSPP structure has lower coupling feature with closely-spaced transmission line circuits than its counterpart traditional HMSIW structure.
New mechanisms for the controlled growth of one‐dimensional (1D) metal–organic framework (MOF) nano‐ and superstructures under size‐confinement and surface‐directing effects have been discovered. ...Through applying interfacial synthesis templated by track‐etched polycarbonate (PCTE) membranes, congruent polycrystalline zeolitic imidazolate framework‐8 (ZIF‐8) solid nanorods and hollow nanotubes were found to form within 100 nm membrane pores, while single crystalline ZIF‐8 nanowires grew inside 30 nm pores, all of which possess large aspect ratios up to 60 and show preferential crystal orientation with the {100} planes aligned parallel to the long axis of the pore. Our findings provide a generalizable method for controlling size, morphology, and lattice orientation of MOF nanomaterials.
Templated interfacial synthesis was applied to metal–organic framework (MOF) growth under both size‐confinement and surface‐directing effects. This led to congruent polycrystalline MOF nanorods and nanotubes, and single crystalline nanowires with large aspect ratios up to 60 and controlled crystal lattice orientation.
With the growing popularity of electrical communication equipment, high-performance electromagnetic interference (EMI) shielding materials are widely used to deal with radiation pollution. However, ...the large thickness and poor mechanical properties of many EMI shielding materials usually limit their applications. In this study, ultrathin and highly flexible Ti3C2T x (d-Ti3C2T x , MXene)/cellulose nanofiber (CNF) composite paper with a nacre-like lamellar structure is fabricated via a vacuum-filtration-induced self-assembly process. By the interaction between one-dimensional (1D) CNFs and two-dimensional (2D) d-Ti3C2T x MXene, the binary strengthening and toughening of the nacre-like d-Ti3C2T x /CNF composite paper has been successfully achieved, leading to high tensile strength (up to 135.4 MPa) and fracture strain (up to 16.7%), as well as excellent folding endurance (up to 14 260 times). Moreover, the d-Ti3C2T x /CNF composite paper exhibits high electrical conductivity (up to 739.4 S m–1) and excellent specific EMI shielding efficiency (up to 2647 dB cm2 g–1) at an ultrathin thickness (minimum thickness 47 μm). The nacre-inspired strategy in this study offers a promising approach for the design and preparation of the strong integrated and flexible MXene/CNF composite paper, which may be applied in various fields such as flexible wearable devices, weapon equipment, and robot joints.
Metal halide perovskites (MHPs) have recently attracted great attention from the scientific community due to their excellent photovoltaic performance as well as their tremendous potential for other ...optoelectronic applications such as light‐emitting diodes, lasers, and photodetectors. Despite the rapid progress in device applications, a solid understanding of the photophysical properties behind the device performance is highly desirable for MHPs. Here, the properties of excitons and photogenerated charge carriers in MHPs are explored. The unique dielectric constant properties, crystal–liquid duality, and fundamental optical processes of MHPs are first discussed. The properties of excitons and related phenomena in MHPs are then detailed, including the exciton binding energy determined by various methods and their influence factors, exciton dynamics, exciton–photon coupling and related applications, and exciton–phonon coupling in MHPs. The properties of photogenerated free charge carriers in MHPs such as the carrier diffusion length, mobility, and recombination are described. Recent progress in various applications is also demonstrated. Finally, a conclusion and perspectives of future studies for MHPs are presented.
The properties of excitons and photogenerated charge carriers in metal halide perovskites (MHPs) are explored. The properties of excitons including the exciton binding energy, exciton dynamics, and exciton–photon and exciton–phonon coupling, are discussed. The properties of photogenerated free charge carriers in MHPs such as diffusion length, mobility, and recombination are described. A brief review of recent applications is also demonstrated.
A class of millimeter-wave E-plane waveguide bandpass filters (BPFs) based on spoof surface plasmon polaritons (SSPPs) have been presented in this article. Three kinds of SSPPs, with different ...patterns coated on the dielectric substrate, are inserted into the E-plane of WR-10 standard rectangular waveguide for the design of BPFs. To clarify the filtering characteristics of the proposed BPFs, the dispersive properties of different SSPP unit cells are investigated and discussed. The electromagnetic simulation results demonstrate that the bandwidths and center frequencies of the proposed E-plane waveguide BPFs can be flexibly adjusted by controlling the asymptotic frequencies of SSPP unit cells. For verifying the design feasibility, these three E-plane waveguide BPFs are fabricated and measured. Good agreement between measurements and simulations indicates that the proposed idea will be a good candidate for the BPF design with low insertion loss and flexible adjustment of center frequency and bandwidth.
Vital osteocytes have been well known to function as an important orchestrator in the preservation of robustness and fidelity of the bone remodeling process. Nevertheless, some key pathological ...factors, such as sex steroid deficiency and excess glucocorticoids, and so on, are implicated in inducing a bulk of apoptotic osteocytes, subsequently resulting in resorption-related bone loss. As much, osteocyte apoptosis, under homeostatic conditions, is in an optimal state of balance tightly controlled by pro- and anti-apoptotic mechanism pathways. Importantly, there exist many essential signaling proteins in the process of osteocyte apoptosis, which has a crucial role in maintaining a homeostatic environment. While increasing in vitro and in vivo studies have established, in part, key signaling pathways and cross-talk mechanism on osteocyte apoptosis, intrinsic and complex mechanism underlying osteocyte apoptosis occurs in various states of pathologies remains ill-defined. In this review, we discuss not only essential pro- and anti-apoptotic signaling pathways and key biomarkers involved in these key mechanisms under different pathological agents, but also the pivotal role of apoptotic osteocytes in osteoclastogenesis-triggered bone loss, hopefully shedding new light on the attractive and proper actions of pharmacotherapeutics of targeting apoptosis and ensuing resorption-related bone diseases such as osteoporosis and fragility fractures.
Hydroxyapatite nanowires exhibit a great potential in biomedical applications owing to their high specific surface area, high flexibility, excellent mechanical properties, and similarity to ...mineralized collagen fibrils of natural bone. In this work, zinc‐containing nanoparticle‐decorated ultralong hydroxyapatite nanowires (Zn‐UHANWs) with a hierarchical nanostructure have been synthesized by a one‐step solvothermal method. The highly flexible Zn‐UHANWs exhibit a hierarchical rough surface and enhanced specific surface area as compared with ultralong hydroxyapatite nanowires (UHANWs). To evaluate the potential application of Zn‐UHANWs in bone regeneration, the biomimetic Zn‐UHANWs/chitosan (CS) (Zn‐UHANWs/CS) composite porous scaffold with 80 wt % Zn‐UHANWs was prepared by incorporating Zn‐UHANWs into the chitosan matrix by the freeze‐drying process. The as‐prepared Zn‐UHANWs/CS composite porous scaffold exhibits enhanced mechanical properties, highly porous structure, and excellent water retention capacity. In addition, the Zn‐UHANWs/CS porous scaffold has a good biodegradability with the sustainable release of Zn, Ca, and P elements in aqueous solution. More importantly, the Zn‐UHANWs/CS porous scaffold can promote the osteogenic differentiation of rat bone marrow derived mesenchymal stem cells and facilitate in vivo bone regeneration as compared with the pure CS porous scaffold or UHANWs/CS porous scaffold. Thus, both the Zn‐UHANWs and Zn‐UHANWs/CS porous scaffold developed in this work are promising for application in bone defect repair.
Go nano! Zinc‐containing nanoparticle‐decorated hydroxyapatite nanowires (Zn‐UHANWs) and a biomimetic Zn‐UHANWs/chitosan (CS) (Zn‐UHANWs/CS) composite porous scaffold are synthesized. The porous scaffold exhibits enhanced mechanical properties, excellent water‐retention capacity, good biodegradability, and can promote in vivo bone regeneration (see figure).
As one important component of sulfur cathodes, the carbon host plays a key role in the electrochemical performance of lithium‐sulfur (Li‐S) batteries. In this paper, a mesoporous nitrogen‐doped ...carbon (MPNC)‐sulfur nanocomposite is reported as a novel cathode for advanced Li‐S batteries. The nitrogen doping in the MPNC material can effectively promote chemical adsorption between sulfur atoms and oxygen functional groups on the carbon, as verified by X‐ray absorption near edge structure spectroscopy, and the mechanism by which nitrogen enables the behavior is further revealed by density functional theory calculations. Based on the advantages of the porous structure and nitrogen doping, the MPNC‐sulfur cathodes show excellent cycling stability (95% retention within 100 cycles) at a high current density of 0.7 mAh cm‐2 with a high sulfur loading (4.2 mg S cm‐2) and a sulfur content (70 wt%). A high areal capacity (≈3.3 mAh cm‐2) is demonstrated by using the novel cathode, which is crucial for the practical application of Li‐S batteries. It is believed that the important role of nitrogen doping promoted chemical adsorption can be extended for development of other high performance carbon‐sulfur composite cathodes for Li‐S batteries.
The nitrogen‐doped mesoporous carbon material is found to chemically adsorb sulfur, and the related mechanism is revealed by experimental survey and density functional theory calculation. Taking full advantages of chemical adsorption of sulfur, MPNC‐S cathode delivered an excellent capacity retention (95% within 100 cycles), high Coulombic efficiency (>96%), as well as high areal capacity of above 3 mAh cm‐2.
PDF
