Materials Today Advances最新文献

The strategy of rare-earth elements addition into Mg alloys has been successfully developed and applied to enhance the mechanical performance and corrosion resistance of Mg alloys. Although this strategy has also been applied to enhance their high-temperature oxidation resistance, the mechanistic understanding of the beneficial effects remains elusive. Here, the oxidation of Mg–4Nd and Mg-4Nd–1Y alloys in Ar–20%O₂ at 500 °C was studied and compared. It was found that even though a continuous layer of Nd₂O₃ did not form, the Nd addition could still enhance the oxidation tolerance of Mg–4Nd alloy by facilitating the generation of a more continuous and intact oxide scale and working as oxygen sinks to delay the violent oxidation of Mg. The formation of a continuous Y₂O₃ layer on Mg-4Nd–1Y alloy suggests that Y was more capable of facilitating the external oxidation due to its much faster diffusion rate in Mg matrix than that of Nd. However, the Nd addition could decrease the critical content of Y necessary for the oxidation transition from internal to external because of the synergistic effect of the Nd and Y addition. The dissolution of the thermal unstable Mg₁₂Nd precipitates resulted in a localized increase of Nd content, accelerating the oxidation by increasing the preferential oxidation of Nd. Hence, in the design of oxidation-resistant Mg alloys, the addition of RE elements with faster diffusion rate and the addition of multiple alloy elements are preferred. In addition, the number of thermal unstable precipitates needs to be strictly controlled.

Antibacterial properties are critical for implants, while general pure titanium implants are bioinert. Adding nano Ag to metals is an effective strategy to obtain antibacterial properties. However, the comprehensive properties of Ti–Ag alloy prepared by traditional methods are not satisfactory. In this paper, Ti–5Ag alloy with an antibacterial rate close to 100 % was synthesized in situ by laser powder bed fusion (LPBF), and its microstructure and properties were studied systematically. Phase analysis demonstrated the existence of Ti₂Ag which played an important role in gaining excellent antibacterial properties. Benefiting from in situ laser alloying, the elements were homogeneously distributed, which endowed the Ti–5Ag alloy with excellent mechanical properties and corrosion resistance. The tensile strength and elongation reached 716 MPa and 33.51 %, respectively. Furthermore, through the design of triply periodic minimal surface (TPMS) structures, mechanical properties matching human bone were obtained. Based on LPBF-printed Ti–5Ag alloy and TPMS structures, this paper provides a feasible method for the manufacturing of bone implants with excellent comprehensive properties.

Mycoplasma contamination in cell/tissue cultures significantly affects cell characteristics, susceptibility to infectious pathogens, and drug reactions without obvious morphological changes and noticeable changes in cell growth rates. Although the technology for screening mycoplasma is essential, conventional technologies have limitations in the selection of a quick and easy manner. Here, we introduce an innovative screening system for mycoplasma based on electrochemical methods. In the electrochemical screening, a newly designed electrode, consisting of a sandwich-DNA hybridization for high selectivity and a nano-amplifier to improve the sensitivity, has implemented a realistic screening system by presenting detection capability at extremely low (ng/μL) levels and detection potential in real samples. Therefore, this system offers rapid screening, data accuracy, temporal effectiveness, and affordable-and-portable installation, enabling timely elimination of Mycoplasma contamination and facilitating progress in biomedical and pharmaceutical research.

Emerging technologies such as neuromorphic computing and nonvolatile memories based on floating gate field-effect transistors (FETs) hold promise for addressing a wide range of artificial intelligence tasks. For example, neuromorphic computing seeks to emulate the human brain's functionality and employs a device that mimics the role of a synapse in the brain. However, achieving a high current ON/OFF ratio for the program and erase states of nonvolatile memory and neuromorphic computing device with a metal gate is necessary. This study demonstrates a multi-functional device based on heterostructures of transition metal dichalcogenides (TMDCs) with a metal floating gate. Five different channel materials (SnS₂, WSe₂, MoS₂, WS₂, and MoTe₂) were employed, and hexagonal boron nitride (h-BN) was used as a tunneling layer. The study found that n-type SnS₂ exhibits high endurance (15,000 cycles), good retention (2.4 × 10⁵ s), and the highest current ON/OFF ratio (∼2.58 × 10⁸) among the materials for the program and erase states. Moreover, the SnS₂ device exhibits synaptic behavior and offers highly stable operation at room temperature. Furthermore, the device shows high linearity in both potentiation and depression, with good retention time and repeatable results with low cycle-to-cycle variations. Additionally, the study used an artificial neural network (ANN) for MNIST simulation of image recognition and achieved the highest accuracy of ∼92 % based on the SnS₂ synaptic device experimental results. These findings pave the way for developing nonvolatile memory devices and their applications in brain-inspired neuromorphic computing and artificial intelligence systems.

Controlled immune response, enhanced osteogenesis, and antibacterial effect are essential for successful implanted biomaterials in the long-term. However, the previous research only considers one of the above-mentioned materials’ properties, and the potential synergetic effects are still unknown. Inspired by the mussel adhesion-mediated ions-coordinated strategy, a multifunctional coating integrated with bioactive Sr²⁺ and antibacterial Cu²⁺ was fabricated the multifunctional PEEK implants (PEEK-PDA-Sr/Cu). Compared to the uncoating PEEK, the PEEK implants with a multifunctional coating can regulate the M1 subtypes of macrophages to M2 subtypes due to the presence of Sr²⁺, which further promote the osteogenic differentiation of BMSCs. Even under the bacterial infection environment, the PEEK implants with a multifunctional coating can still enhance the osseointegration of bone implants due to the antibacterial properties of Cu²⁺. Taken together, PEEK implants with a multifunctional coating can provide an osteogenic immune microenvironment with enhanced osteogenesis and antibacterial property, which is essential for successful implantation in the long-term.

This study utilized various phosphorus-ion implantation techniques, incorporating low, medium, and high doses, to investigate the electrical properties of unintentionally doped β-Ga2O3 epilayers. These epilayers were grown on sapphire substrates by metalorganic chemical vapor deposition.

Specifically, the low-dose implantation involved phosphorus ions at concentrations of 1.6✕10¹³, 1✕10¹² and 2.5✕10¹² atoms/cm², administered at implantation energies of 100, 50, and 40 keV, respectively. The medium-dose implantation utilized phosphorus ions at concentrations of 1.6✕10¹⁴, 1✕10¹³ and 2.5✕10¹³ atoms/cm², at the same implantation energies. Finally, the high-dose implantation employed phosphorus ions at concentrations of 1.6✕10¹⁵, 1✕10¹⁴ and 2.5✕10¹⁴ atoms/cm², with implantation energies of 100, 50, and 40 keV, respectively. The implantation parameters were also simulated using the Stopping and Range of Ions in Matter software, while the actual concentration of phosphorus ions was measured via secondary ion mass spectrometry. Subsequently, Ni and Au were deposited on the annealed phosphorus-implanted β-Ga₂O₃ epilayers, followed by rapid thermal annealing at 600 °C in a nitrogen environment for 1 min, for Hall measurement. The electrical properties of the phosphorus-implanted β-Ga₂O₃ epilayers were assessed through Hall measurements. Notably, the β-Ga₂O₃ epilayers implanted with middle and high doses displayed p-type behavior. The resistivity of the p-type β-Ga₂O₃ epilayers with middle and high doses measured 9.699 and 6.439 Ω cm, respectively, as determined by Hall measurements. Additionally, the hole carrier concentrations for these doses were measured as 1.612 × 10¹⁸ and 6.428 × 10¹⁷, respectively. Consequently, the phosphorus ion implantations using middle and high doses were proven effective in obtaining p-type Ga₂O₃. To further explore the defect formation energies and Fermi energies of substitutional phosphorus defects within the β-Ga₂O₃ lattices, first-principles density-functional simulations were employed.

In this work, a three-dimensional porous carbon structure was constructed in situ by connecting carbon polyhedrons with graphitic nanosheets. The rich pores, high nitrogen doping content, and abundant defects formed on the surface provided multiple antennas to absorb electromagnetic waves. The optimized reflection loss of the material was as low as −41.65 dB with an effective absorption band of 5.84 GHz, which covered the entire Ku band. A mechanistic investigation based on density functional theory calculations and electrochemical analysis shows that the dipole loss and conduction loss were mainly caused by pyrrolic nitrogen and the higher electron mobility in the prepared materials. The conduction loss and polarization loss synergistically improve the absorption performance of nanosheet-linked porous carbon (NLPC). Furthermore, the potential practical application performance of the material, which was evaluated by computer simulation technology (CST), showed that all simulated RCS values were lower than 20 dBm². Thus, this work provides new insights and methods to understand the microwave absorption properties of carbon materials.

In order to develop materials for energy storage, a bulk nanocomposite with a composition of FeTi-25 vol% Cu was prepared by high-pressure torsion, with FeTi as functional phase for hydrogen storage and Cu as ductile phase to improve the processability. Despite the use of such a highly ductile auxiliary phase, the processability remained challenging due to strain localization in the softer Cu. This behavior is most pronounced at room temperature, and no nanocomposites were formed. At elevated temperatures, the strong strain rate sensitivity of the flow stress of the nanocrystalline Cu facilitates the formation of a FeTi–Cu nanocomposite due to a self-reinforcing process. Nevertheless, fragmentation of FeTi is limited because the resulting massive strain hardening prevents controlled processing at temperatures <250 °C, and Cu-rich shear bands develop at temperatures >250 °C. Satisfactory microstructural homogeneity is only achieved at the highest deformation temperatures of 550 °C. Overall, this study highlights that for unlikely material pairings, as often required in the pursuit of superior functional materials, the mechanical behavior of the phases involved and their interplay remains critical and must be thoroughly investigated when aiming for controlled structural homogeneity of bulk nanomaterials.

Polymer scaffolds are an important enabling technology in tissue engineering. A wide range of manufacturing techniques have been developed to produce these scaffolds, including porogen leaching, phase separation, gas foaming, electrospinning and 3D printing. However, all of these techniques have limitations. Delivering suitable scaffold porosity, small feature sizes and macroscopic geometry remain challenging.

Here, we present the development of a highly versatile scaffold fabrication method utilising emulsion templating to produce polymerised high internal phase emulsions (polyHIPEs) of the polymer poly(glycerol sebacate) methacrylate (PGS-M). PGS-M is biocompatible, degradable and highly elastic, with tunable mechanical properties. PGS-M was formulated into an emulsion using solvents and surfactants and then photocured into polyHIPE structures. The porosity, degradation behaviour, mechanical properties and biocompatibility of the PGS-M polyHIPEs was investigated.

The versatility of the PGS-M polyHIPEs was demonstrated with the production of various complex tubular scaffold shapes, using injection moulding. These shapes were designed for applications in vascular graft tissue engineering and included straight tubes, bends, branches, functioning valves, and a representative aortic arch. The PGS-M polyHIPE scaffolds supported vascular smooth muscle cells (SMCs) in 3D cell culture in a bioreactor.

Light emission with delicate wavelength control generates fundamental colors that are essential for vision-based applications such as displays, information communication, visual and augmented reality. Yet these light emitting technologies critically rely on the development of photonic sources for proper lighting and color matching. Halide perovskites have recently emerged as excellent and efficient photonic sources due to their outstanding photophysical properties, such as low defect trap densities, long carrier lifetime, large absorption coefficient, high quantum yield and optical gain. On a par with the rapid advances of light-emitting diodes (LEDs), perovskite-based optical amplifiers and lasers have made great strides in the past few years, which have much more accurate control of color-matched lighting, high power, spatial and wavevector control of color emission. In this review, we aim to review the recent progress of perovskite lasers at micro-, nano- and subwavelength scales, discuss the properties of halide perovskites and optical cavity structures that benefit color light emission, and examine the remaining challenges in the field for the future development of perovskite-based lasing technologies.