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High-entropy ceramics and their composites display high mechanical strength and attractive high-temperature stabilities. However, properties like strong covalent bond character and low self-diffusion coefficients make them difficult to get sintered, limiting their mass popularity. Here, we present a rapid liquid phase-assisted ultrahigh-temperature sintering strategy and use high-entropy metal diboride/boron carbide composite as a proof of concept. We use a carbon-based heater to fast-heat the composite to around 3000 K, and a small fraction of eutectic liquid was formed at the interface between high-entropy metal diborides and boron carbide. A crystalline dodecaboride intergranular phase was generated upon cooling to ameliorate the adhesion between the components. The as-sintered composite presents a high hardness of 36.4 GPa at a load of 0.49 N and 24.4 GPa at a load of 9.8 N. This liquid phase-assisted rapid ultrahigh-temperature strategy can be widely applicable for other ultrahigh-temperature ceramics as well.

Bioceramics provide promising tactics for wound healing, yet the on‐shelf products are still unmet, especially for skin appendages regeneration. Herein, the inorganic magnesium silicate sprays (MSS) as mineral factors to overcome the existing challenges is proposed. Results indicate MSS can be synthesized by a green method without organic solvents, templates, calcination, and harmful by‐products. With amorphous phase, nanoscale, and high specific surface area, MSS reveal an improved pH‐responsive degradability and excellent bioactivity for cell proliferation and migration. In rats, MSS display a dose‐dependent effect on accelerating burn‐wound repair via regulating the expressions of iNOS and IL‐10 to attenuate inflammation, elevating the expressions of CD31 and α‐SMA to improve vascularization, and boosting collagen deposition without ectopic calcification. The released Mg and Si ions synergistically potentiate the expressions of Gap43, Tubb3, and K19, suggesting the regeneration of peripheral nerves and hair follicles. These superior features are further verified by comparisons with commercial products, Dermlin® and 45S5 bioglass®, in both rats and minipigs. Motivated by these findings, three MSS‐based formulations of band‐aid patch, adhesive hydrogel, and antibacterial sprays are devised for specific scenarios. Taken together, this proof‐of concept study provides a promising bioactive mineral for future clinical skin wound repair and functional appendages regeneration. [ABSTRACT FROM AUTHOR]

The dynamics of nanoparticle growth in pulsed anodic arc discharge has been studied in time-resolved mode. To this end, a fast moving probe was employed to extract the material generated in a pulsed arc plasma held between two graphite electrodes. The probe motion was synchronized with the pulse phase and the exposure time to the plasma was set to 10 ms. The graphite anode was eroded in a helium atmosphere (300 Torr) by an arc plasma pulsed at 1 Hz with a 10% duty cycle and showing 250 A of peak current. The structure and morphology of the probe depositions were characterized by Raman spectroscopy, scanning electron microscopy, and focused ion beam. A maximal deposition rate of 260 μm/s was measured 5 mm away from the arc core during the active 0.1 s of the pulse. Such a rate yields a growth flux of 1.3 × 1021 cm−2 s−1, rich in carbon nanostructures (graphene platelets, nanotubes) with a characteristic aggregate size within 1–10 μm. The deposition during the inactive 0.9 s of the pulse was several orders of magnitude slower and consisted of amorphous carbon traces. Moreover, the nanoparticle distribution along the collecting probe is correlated with the pulse phase, thereby providing information on particle transport. Pulsed nanosynthesis can be modeled as a periodical growth process, where the volume and propagation velocity of the growth region can be adjusted through modulation of the pulse signal waveform. The proposed model constitutes a suitable framework to investigate the pulsed arc synthesis of nanomaterials with tailored physical and chemical properties. [ABSTRACT FROM AUTHOR]

Elemental vacancies are proposed as an effective approach to tuning the electronic structure of catalysts that are critical for energy conversion. However, for reactions such as the sluggish oxygen evolution reaction, the excess of oxygen vacancies (VO) is inevitable and detrimental to catalysts' electrochemical stability and activities, e.g., in the most active RuO2. While significant work is carried out to hinder the formation of VO, the development of a fast and efficient strategy is limited. Herein, a protection SrO layer produced successfully at the surface of RuO2 with the in situ exsolution method with perovskite SrRuO3 as the precatalyst, which could significantly hinder the generation of VO. Benefited from the suppression of VO, the surface‐modified RuO2 requires a low overpotential of 290 mV at 100 mA cm−2, accompanied by remarkably high electrochemical stability (100 h) and Faraday efficiency (≈100%). Theoretical investigation reveals that the formation energy of VO in RuO2 is almost doubled in the exsolved RuO2 phase as a result of the weakened RuO bond covalency. This work not only provides insight into the structural evolution of perovskite oxide catalysts but also demonstrates the feasibility of controlling vacancy formation via in situ exsolution. [ABSTRACT FROM AUTHOR]