Materials Today Advances最新文献

Thermal insulation is crucially important to the safety and reusability of aerospace vehicles. Fabrication of thermal insulation materials with light weight, high mechanical strength and low thermal conductivity remains challenging. In this study, porous polymer derived silicon oxycarbide (SiOC) ceramics with hierarchical structures mimicking cuttlebones were prepared through stereolithography additive manufacturing followed by pyrolysis. The compressive strength of SiOC ceramics with ridges (“R” structures) alongside the sinusoidal walls (“S” structures) (RS-SiOC, 13.37 ± 0.86 MPa for 7-RS-SiOC) mimicking those of cuttlebone was much higher than that of SiOC ceramics with just sinusoidal walls (S–SiOC, 8.43 ± 0.81 MPa), while the density of RS-SiOC with 7 ridges (7-RS-SiOC) and S–SiOC were 0.40 g/cm³ and 0.39 g/cm³, respectively. Our results revealed that the tailored “S” and “R” structures of biomimetic 7-RS-SiOC ceramics, together with the amorphous network of SiOC assembled in the layer-by-layer manner, rendered the high mechanical strength. In addition, the 7-RS-SiOC sample exhibited a low thermal conductivity of 0.12 W/(m·K) at room temperature. The back temperature of the 7-RS-SiOC sample was 179.5 °C when exposed to 800 °C for 1200 s, showing excellent thermal insulation capability. The state-of-the-art biomimetic design of lightweight SiOC ceramics likely offers a solution to high-performance thermal insulation for aerospace vehicles.

Nanostructured manganese oxides (MnO_x) have shown incredible promise in constructing next-generation energy storage and catalytic systems. However, it has proven challenging to integrate with other low-dimensional materials due to harsh deposition conditions and poor structural stability. Here, we report the deposition of layered manganese dioxide (δ-MnO₂) on bilayer epitaxial graphene (QEG) using a simple three-step electrochemical process involving no harsh chemicals. Using this process we can synthesize a 50 nm thick H–MnO₂ film in 1.25s. This synthetic birnessite is inherently water-stabilized, the first reported in the literature. We also confirm that this process does not cause structural damage to the QEG, as evidenced by the lack of D peak formation. This QEG heterostructure enhanced MnO₂'s redox active gas sensing, enabling room temperature detection of NH₃ and NO₂. We also report on transforming this δ-MnO₂ to other MnO_x compounds, Mn₂O₃ and Mn₃O₄, via mild annealing. This is confirmed by Raman spectroscopy of the films, which also confirms limited damage to the QEG substrate. To our knowledge, this is the first synthesis of Mn₂O₃ and Mn₃O₄ on pristine graphene substrates. Both methods demonstrate the potential of depositing and transforming multifunctional oxides on single-crystal graphene using QEG substrates, allowing for the formation of nanostructured heterostructures previously unseen. Additionally, the electrochemical nature of the deposition presents the ability to scale the process to the QEG wafer and adjust the solution to produce other powerful multifunctional oxides.

Carbon-based nanomaterials are key to developing high-performing electrochemical sensors with improved sensitivity and selectivity. Nonetheless, limitations in their fabrication and integration into devices often constrain their practical applications. Moreover, carbon nanomaterials-based electrochemical devices still face problems such as large background currents, poor stability, and slow kinetics. To advance towards a new class of carbon nanostructured electrochemical transducers, we propose the in-situ polymerization and carbonization of furfuryl alcohol (FA) on porous silicon (pSi) to produce a tailored and highly stable transducer. The thin layer of polyfurfuryl alcohol (PFA) that conformally coats the pSi scaffold transforms into nanoporous carbon when subjected to pyrolysis above 600 °C. The morphological and chemical properties of PFA-pSi were characterized by scanning electron microscopy, and Raman and X-ray photoelectron spectroscopies. Their stability and electrochemical performance were investigated by cyclic voltammetry and electrochemical impedance spectroscopy in [Fe(CN)₆]^3-/4-, [Ru(NH₃)₆]^2+/3+, and hydroquinone. PFA-pSi showed superior electrochemical performance compared to screen-printed carbon electrodes while also surpassing glassy carbon electrodes in specific aspects. Besides, PFA-pSi has the additional advantage of easy tuning of the electroactive surface area. To prove its potential for biosensing purposes, a DNA sensor based on quantifying the partial pore blockage of the pSi upon target hybridization was built on PFA-pSi. The sensor showed a limit of detection of 1.4 pM, outperforming other sensors based on the same sensing mechanism.

Fabrication technologies based on electro-hydrodynamic processes have been extensively studied in the past decades. Near-field electrospinning (NFES), based on a stable cone-jet mode, is widely used to fabricate micro- and nano-scale fibrous structures for a variety of applications. However, previous reviews have given limited attention to the capabilities of NFES to fabricate 2D and 3D structures. This review introduces four key metrics of NFES capabilities, i.e., fidelity, resolution, response, and aspect ratio, to evaluate and summarize the advances of NFES technology. Specifically, the fundamental theories of the electro-hydrodynamic process are discussed to understand the effect of operating parameters on the metrics of NFES capabilities. Then, the methods to improve the metrics of NFES capabilities are summarized. Furthermore, the applications of NFES technology are reviewed by highlighting the functionality of each metric of the capabilities. Finally, the achievements and existing gaps in NFES technology are discussed to offer insights into future directions in the field.

Magnesium (Mg) alloys have great potential as biodegradable materials for medical device. However, their susceptibility to corrosion poses a significant challenge for practical applications. In this study, the poly(trimethylene carbonate)-dimethacrylate (PTMC-dMA) was employed as a coating material for ZE21B magnesium alloys. Upon UV irradiation, the PTMC-dMA macromer undergoes cross-linking to form a uniform PTMC coating with a thickness of approximately 5 μm, effectively protecting the magnesium alloy. The corrosion resistance in simulated body fluid (SBF) was evaluated through immersion testing, which showed minimal hydrogen generation (0.16 mL/cm²) during the initial 24-h period and slight corrosion observed on the PTMC-coated magnesium alloy surface after continuous immersion for 21 days. The silane coupling agent significantly enhanced the adhesive performance between the polymer and alloy. Micro-scratch tests revealed adhesion forces of 3.79 N and 5.75 N for coatings without and with the silane agent, respectively. Electrochemical tests also demonstrated the efficacy of silane treatment, showing corrosion currents of 2.100 × 10⁸ A/cm² for silane-treated samples compared 6.263 × 10⁷ A/cm² for untreated ones. Given its exceptional tensile and protective properties, this coated material is ideal for intricate bioresorbable applications, like endovascular bioresorbable stents.

Chronic diabetic cutaneous wounds resulting from inflammatory conditions present an ongoing challenge for current therapies and impose a significant burden on individuals with diabetes, impacting their quality of life. Infection-related diabetic skin wounds require dry conditions to inhibit bacterial growth. However, as the wounds progress, moisture becomes necessary to facilitate the healing process. In this study, we propose a novel therapeutic strategy for diabetic skin repair by creating bio-dressings with adjustable “hydrophobic” and “hydrophilic” characteristics to accommodate the changing stages of the disease. We developed a skin dressing by loading calcium peroxide (CaO₂) nanoparticles onto carbon dots (CD)-modified irradiated zein (Ir-Zein). This dressing releases reactive oxygen species (ROS) from CaO₂, providing antibacterial effects, while the presence of CD enables a sustained release of CaO₂. The calcium ions produced by CaO₂ degradation further promote skin regeneration. Ir-Zein protein, a cost-effective and easily processed natural plant protein, exhibits excellent biocompatibility. Importantly, in diabetic rats with full-thickness skin defects, the CaO₂/CD@Ir-Zein film significantly accelerated the healing of chronic wounds. Mechanistic investigations revealed that the film effectively reduced inflammation by inhibiting the polarization of macrophages towards the M1 phenotype and capturing pro-inflammatory cytokines. In summary, our findings demonstrate the effectiveness of the CaO₂/CD@Ir-Zein film’s “adaptive hydrophobicity-to-hydrophilicity” in promoting the transition of chronic wounds from the inflammatory stage and skin repair. CaO₂/CD@Ir Zein is a novel bio-dressing that can adapt to the changing environment of infected diabetic skin wound healing.

The precise structural design and reproducible manufacturing advantages of the 3D printed scaffold make it attract attention in clinical applications. However, the inability of scaffolds to achieve internal and external co-induced vascularized osteogenesis limits their application. After observing the ingenious and functionalized structural combination of "pinecone", this study prepared hydrogel microspheres encapsulating strontium ranelate (SrR)-dendrimer (PAMAM) as a functionalized "pine nuts" through microfluidic technology. The 3D-printed Polycaprolactone (PCL) scaffold was used as a framework in which hydrogel microspheres and a 3D-printed scaffold were cleverly combined. In this pinecone 3D-scaffold system, the slow release of SrR is beneficial to promote vascularization and osteogenic differentiation inside and outside the scaffold. Furthermore, the rat femoral defect model verified that the pinecone scaffold promoting the formation of internal vascular network, osteogenic differentiation and shortening the bone repair time in vivo. In summary, this pinecone degradable biomimetic composite scaffold with internal osteogenic differentiation and vascular activation functions has great potential for clinical demand in segmental bone defects.

Compared with conventional metallic glasses, refractory metallic glasses (RMGs) with a mass of refractory element(s), high glass-transition temperature (T_g) and outstanding mechanical properties (like ultrahigh strength, high hardness and good wear resistance) exhibit fascinating potential applications in high temperature field. However, the development of RMGs is painfully slow, and one of the key problems is the lack of rapid and convenient way to screen out high glass-forming refractory alloys. In this study, a method for rapid evaluation of glass forming ability (GFA) based on laser surface remelting was provided. The high-efficiency screening-out method was validated in a classical glass-forming model system of Ni–Nb binary refractory alloys. The effects of different laser parameters on the glass formation and phase evolution were investigated by experimental analysis and finite element simulation. By correlating thermal history of the laser treatment with glass formation, the alloys with high GFA in Ni–Nb system was screened out rapidly. The screening-out efficiency of the novel method can be improved one order of magnitude, compared with that of the conventional techniques, and the materials cost can be reduced, especially for RMGs. The revealed formation mechanism of glassy and crystalline phases in time and spatial distributions influenced by thermal history under multi-scanning laser treatment can provide a significant insight in the construction of the bulk-metallic-glass materials and the related composite ones by laser additive manufactory.