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• Providing a paradigm to achieve excellent thermal stability of nanoprecipitates. • Elucidating evolution behaviors of hierarchical nanostructure in HEA. • Revealing mutual diffusion barrier mechanism between BCC and L1 2 phases in HEA. High-density coherent nanoprecipitates have been widely introduced into the design of new structural materials to achieve a superior strength-ductility balance. However, the thermal instability of nanostructures limits their fabrication and application. In this study, we investigated the temporal evolution of nanoprecipitates in coherent nanoprecipitation-strengthened Al 0.5 Cr 0.9 FeNi 2.5 V 0.2 high-entropy alloy during isothermal aging. When annealed at 600 °C for more than 100 h, we found that its nanoprecipitates were invariably stable, with no obvious changes occurring in terms of morphology and distribution. The excellent stability was mainly attributed to the restricted state of interface migration and diffusion owing to the hierarchical nanostructure. The Cr-enriched nano-lamellar BCC phase divided the Cr-depleted FCC(L1 2) matrix, forming barriers to long-range diffusion and resulting in a kinetically slow coarsening rate. As the nano-lamellar BCC phase spheroidized as the aging temperature increased to 700 °C, the diffusion barriers were destroyed. Remarkable coarsening occurred after that, which further verified the significant effect of the nano-lamellar BCC phase on the microstructural stability. These results provide a paradigm for designing alloys stabilized via hierarchical nanostructure, achieving good strength-ductility synergy while excellent thermal stability. [Display omitted] [ABSTRACT FROM AUTHOR]

Traditional petroleum-based food-packaging materials have poor permeability, limited active packaging properties, and difficulty in biodegradation, limiting their application. We developed a carboxymethylated tamarind seed polysaccharide composite film incorporated with ε-polylysine (CTPε) for better application in fresh-cut agricultural products. The CTPε films exhibit excellent water vapor barrier properties, but the mechanical properties are slightly reduced. Fourier transform infrared spectroscopy and X-ray diffraction spectra indicate the formation of hydrogen bonds between ε-PL and CTP, leading to their internal reorganization and dense network structure. With the increase of ε-PL concentration, composite films showed notable inhibition of postharvest pathogenic fungi and bacteria, a significant enhancement of 2,2′- azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radical-scavenging activity, and gradual improvement of wettability performance. Cytotoxicity experiments confirmed the favorable biocompatibility when ε-PL was added at 0.3% (CTPε2). In fresh-cut bell pepper preservation experiments, the CTPε2coating effectively delayed weight loss and malondialdehyde increase preserved the hardness, color, and nutrients of fresh-cut peppers and prolonged the shelf life of the fresh-cut peppers, as compared with the control group. Therefore, CTPε composite films are expected to be a valuable packaging material for extending the shelf life of freshly cut agricultural products.

The conformal growth of a high-quality ferromagnet (Cr2Te3) on the nanostructures of a topological insulator (Bi2Te3) was realized via molecular beam epitaxy (MBE). A large topological Hall effect (THE) (∼400 nΩ cm) was unambiguously observed up to 95 K, which provided the evidence for the existence of magnetic spin textures such as magnetic skyrmions in this system. Detailed atomic structure characterizations revealed that black-phosphorus-like Bi nanosheets were embedded in the Cr2Te3lattice and densely stacked above the Bi2Te3nanodots. A nanoscale formation mechanism of the embedded Bi nanosheets was then proposed, demonstrating that the embedded Bi nanosheets were released from the Bi2Te3nanodots in the van der Waals epitaxy process of Cr2Te3. Remarkably, as the large spin–orbital coupling of the embedded Bi nanosheets can stimulate the generation of magnetic skyrmions at the interfaces between them and Cr2Te3, the observed large THE may be attributed to the skyrmions on the densely stacked Bi nanosheets. In summary, our findings demonstrate the reaction between transition-metal Cr and Bi2Te3in the conformal growth of Cr2Te3on Bi2Te3nanodots and provide an efficient and scalable technique to realize future spintronic devices.

Topological Hall effect is an abnormal Hall response arising from the scalar spin chirality of chiral magnetic textures. Up to now, such an effect is only observed in certain special materials, but rarely in traditional ferromagnets. In this work, we have implemented the molecular beam epitaxy technique to successfully embed black-phosphorus-like bismuth nanosheets with strong spin-orbit coupling into the bulk of chromium telluride Cr2Te3, as evidenced by atomically resolved energy dispersive X-ray spectroscopy mapping. Distinctive from pristine Cr2Te3, these Bi-embedded Cr2Te3epitaxial films exhibit not only pronounced topological Hall effects, but also magnetoresistivity anomalies and differential magnetic susceptibility plateaus. All these experimental features point to the possible emergence of magnetic skyrmions in Bi-embedded Cr2Te3, which is further supported by our numerical simulations with all input parameters obtained from the first-principle calculations. Therefore, our work demonstrates a new efficient way to induce skyrmions in ferromagnets, as well as the topological Hall effect by embedding nanosheets with strong spin–orbit couplings.

How an interfacial superconductivity emerges during the nucleation and epitaxy is of great importance not only for unveiling the physical insights but also for finding a feasible way to tune the superconductivity via interfacial engineering. In this work, we report the nanoscale creation of a robust and relatively homogeneous interfacial superconductivity (TC≈ 13 K) on the epitaxial FeTe surface, by van der Waals epitaxy of single-quintuple-layer topological insulator Bi2Te3. Our study suggests that the superconductivity in the Bi2Te3/FeTe heterostructure is generated at the interface and that the superconductivity at the interface does not enhance or weaken with the increase of the Bi2Te3thickness beyond 1 quintuple layer (QL). The observation of the topological surface states crossing Fermi energy in the Bi2Te3/FeTe heterostructure with the average Bi2Te3thickness of about 20 QL provides further evidence that this heterostructure may potentially host Majorana zero modes.

The heterostructures of the ferromagnet (Cr2Te3) and topological insulator (Bi2Te3) have been grown by molecular beam epitaxy. The topological Hall effect as evidence of the existence of magnetic skyrmions has been observed in the samples in which Cr2Te3was grown on top of Bi2Te3. Detailed structural characterizations have unambiguously revealed the presence of intercalated Bi bilayer nanosheets right at the interface of those samples. The atomistic spin-dynamics simulations have further confirmed the existence of magnetic skyrmions in such systems. The heterostructures of ferromagnet and topological insulator that host magnetic skyrmions may provide an important building block for next generation of spintronics devices.

ABSTRACTThe effect of antibiotics on horizontal gene transfer (HGT) is controversial, and the underlying mechanism remains poorly understood. Here, using Escherichia coliSM10λπ as the donor strain, which carries a chromosomally integrated RP4 plasmid, we investigated the effect of antibiotics on conjugational transfer of a mobilizable gentamicin (Gm) resistance plasmid. The results showed that an exposure to gentamicin that restricted the survival of recipient cells significantly enhanced SM10λπ-Pseudomonas aeruginosaPAO1 conjugation, which was attenuated by a deficiency of lasI-rhlI, genes associated with the generation of the quorum sensing signals N-acyl homoserine lactones (AHLs) in PAO1, or the deletion of the AHL receptor SdiA in SM10λπ. Subsequent mechanistic investigations revealed that a treatment with Gm repressed the mRNA expression of lasIand rhlIin PAO1 and upregulated traIexpression in SM10λπ. Moreover, PAO1 treated with other quorum sensing (QS)-inhibiting antibiotics such as azithromycin or chloramphenicol also showed a conjugation-promoting ability. On the other hand, when using non-AHL-producing E. colistrain EC600 as the recipient cells, the promoting effect of Gm on conjugation could not be observed. These data suggest that AHL-SdiA contributes to the effectiveness of antibiotics on plasmid conjugation. Collectively, our findings highlight the HGT-promoting effect of antibiotics and suggest quorum sensing as a promising target for controlling antibiotic resistance dissemination. These findings have implications for assessing the risks of antibiotic use and developing advisable antibiotic treatment protocols.