Hydrogen-rich compounds are considered most likely to achieve room-temperature superconductivity since the critical temperature (T c) above 250 K was observed in lanthanum hydride. Exploring the high-temperature superconductivity in rare-earth metal hydrides becomes very interesting. Based on the particle swarm optimization for crystal structures and first-principles calculations, we investigate the crystal structures, phase stability, metallization, and possible superconducting properties of terbium hydride (TbH n , n = 1 – 12) under pressure. Our results show that terbium hydride is a potential high-temperature superconductor under high pressures. It stably exists at different pressure conditions by adjusting the H content. Specifically, the H atomic cage structure can be observed in most terbium hydrides, and the number of H atoms in the cage sublattice increases with the stoichiometry of H in TbH n . We demonstrate that the high T c value is closely related to this cage sublattice and it increases with increasing H content in terbium hydride. The highest T c above 270 K is predicted in TbH10 at 250 GPa for Fm3̅m and 310 GPa for R3̅m space group. This result indicates that the superconductivity with T c close to or beyond lanthanum hydride can be achieved in other rare-earth metal hydrides.

Staphylococcal enterotoxin A (SEA) is a worldwide public health problem accounting for the majority of food poisoning which is produced by Staphylococcus aureus, threatening human health and leading to various foodborne diseases. Therefore, it is of great significance to develop a sensitive detection method for SEA to ensure food safety and prevent foodborne diseases in humans. In this study, an adaptive fluorescence biosensor for the detection of staphylococcal enterotoxin A (SEA) was designed and developed by combining DNA silver nanoclusters (DNA-AgNCs) with polypyrrole nanoparticles (PPyNPs). Fluorescent AgNCs, synthesized using aptamers as templates, were used as fluorescence probes, whose fluorescence was quenched by PPyNPs. In the presence of the target SEA, DNA-AgNCs were forced to desorb from the surface of PPyNPs through the binding of SEA with the aptamer-DNA-AgNCs, thereby resulting in fluorescence recovery. Under the optimized conditions, the relative fluorescence intensity (FI) showed a linear relationship with the SEA concentration in the range from 0.5 to 1000 ng/mL (Y = 1.4917X + 0.9100, R2 = 0.9948) with a limit of detection (LOD) of 0.3393 ng/mL. The sensor was successfully used to evaluate the content of SEA in milk samples, and the recovery efficiency of SEA was between 87.70% and 94.65%. Thus, the sensor shows great potential for application in food analysis. In short, the proposed platform consisted of an aptamer fluorescent sensor that can be used for the ultrasensitive detection of various toxins by taking advantage of the excellent affinity and specificity of corresponding aptamers.

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To understand the superconductivity and explore the improvement of transition temperature of H 3 S, we investigate the effect of electron or hole injection in H 3 S with the Im3̅ m phase. The results show that the increase of electron−phonon coupling constant mainly comes from the softening of phonons when electrons are introduced, while the electron−phonon coupling strength mainly depends on the change of the electronic density of states at Fermi level when holes are introduced. We find that the introduction of holes can improve the transition temperature, and the increase of hole concentration can further reduce the lowest pressure point satisfying the stability. In the range of 0.3−0.5 hole per unit cell, the transition temperature of the charged H 3 S can be improved to 253 K, which is about 25% larger than the neutral case (204 K at 200 GPa), and the lowest pressure point satisfying the stability is reduced to 140 GPa. Combining the hole doping with the pressure effect, we reveal that the enhancement of transition temperature is driven by the increase of electronic states at Fermi level and the softening of phonons. As a result, a novel way is suggested to further optimize the transition temperature of hydrogen-rich materials.

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Defect engineering with the active control of defect states brings remarkable enhancement on surface-enhanced Raman scattering (SERS) by magnifying semiconductor–molecule interaction. Such light-trapping architectures can increase the light path length, which promotes photon–analytes interactions and further improves the SERS sensitivity. However, by far the reported semiconductor SERS-active substrates based on these strategies are often nonuniform and commonly in the form of isolated laminates or random clusters, which limit their reliability and stability for practical applications. Herein, we develop self-grown single-crystalline “V-shape” SnSe2‑x (SnSe1.5, SnSe1.75, SnSe2) nanoflake arrays (SnSe2‑x NFAs) with controlled selenium vacancies over large-area (10 cm × 10 cm) for ultrahigh-sensitivity SERS. First-principles density functional theory (DFT) is used to calculate the band gap and the electronic density of states (DOS). Based on the Herzberg–Teller theory regarding the vibronic coupling, the results of theoretical calculation reveal that the downshift of band edge and high DOS of SnSe1.75 can effectively enhance the vibronic coupling within the SnSe1.75–R6G system, which in turn enhances the photoinduced charge transfer resonance and contributes to the SERS activity with a remarkable enhancement factor of 1.68 × 107. Furthermore, we propose and demonstrate ultrasensitive (10–15 M for R6G), uniform, and reliable SERS substrates by forming SnSe1.75 NFAs/Au heterostructures via a facile Au evaporation process. We attribute the superior performance of our SnSe1.75 NFAs/Au heterostructures to the following reasons: (1) selenium vacancies and (2) synergistic effect of the near and far fields. In addition, we successfully build a detection platform to achieve rapid (∼15 min for the whole process), antibody-free, in situ, and reliable early malaria detection (100% detection rate for 10 samples with 160 points) in whole blood, and molecular hemozoin (<100/mL) can be detected. Our approach not only provides an efficient technique to obtain large-area, uniform, and reliable SERS-active substrates but also offers a substantial impact on addressing practical issues in many application scenarios such as the detection of insect-borne infectious diseases.