BiOCl has recently elicited intense interest for its excellent photochemical catalysis, energy conversion, and photodetection performance. In this Letter, we systematically investigate BiOCl electronic properties, lattice dynamics, and structural stability. From first-principles calculations, bulk and monolayer BiOCl have ultraviolet indirect band gaps around 3.6 eV, consistent with reflection spectroscopy measurements. The large spin−orbit coupling effect of the Bi atom makes the lowest conduction band near the Z point in the Brillouin region move down 230 meV. However, because of the symmetrical crystal potential, BiOCl has no strong Rashba effect. We further observed all 6 BiOCl Raman-active modes with the lowest-frequency rigid layer in-plane vibrational mode at 63 cm −1 , consistent with our calculations. Up to 500 K or down to monolayer thickness, the crystal structure of BiOCl remains stable. Our work provides detailed information on BiOCl electronic and vibrational properties and stability up to high temperature or down to monolayer, identifying it as a promising layered material for further nano-optoelectronic applications.

treatments: fluorination, [18] nonmetal, [19] or transition-metal atoms [20] adsorption, phase transition [21] and substitution doping with transition-metal (TM) atoms, [22,23] NM metal atoms [23,24] or nonmetal elements. [23,25] Intriguingly, Zhang et al. [26] found an obvious magnetic transition from NM to FM ordering in N-doped ReS 2 nanospheres experimentally. Subsequently, distorted monolayer ReS 2 with ferroelectric and ferromagnetic orders at above room temperature (RT) was synthesized by Zhang et al. [27] On the other hand, nonmagnetic TaS 2 , TaSe 2 , NbS 2 , NbSe 2 , and M 2 C (Hf, Nb, Sc, Ta, V) monolayers [6,9,28,29] could become ferromagnetic (FM) under biaxial tensile strain. In contrast, other theoretical studies had also shown that the magnetic moments of monolayer VS 2 and VSe 2 , [30,31] monolayer PtSe 2 with V Se , [32] and SnSe 2 armchair nanoribbons [33] could be enhanced rapidly with increasing biaxial tensile strain. However, it was very difficult to apply biaxial strain directly on 2D materials. Luckily, experimental methods, including piezoelectric stretching [34] and exploiting the thermal expansion mismatch, [35] had been performed, but these methods required additional sophisticated setups such as electromechanical device or focused laser beam. Thus, it is necessary to investigate alternative convenient ways to apply biaxial strain and explore its effect on the magnetic properties of ReS 2 .Here, we demonstrate the spontaneous formation of largescale web buckles from PAD-grown ReS 2 thin films. Raman spectroscopy and mapping confirm the grown-induced and buckled-induced strain of ReS 2 web buckles. Additionally, we examine the Raman peak position and intensity variations observed in ReS 2 web buckles and explore the magnetism to such strain variations. The temperature coefficients χ T of the films is estimated to be −(0.0087 ± 0.0008) cm −1 K −1 (flat zones) and −(0.0080 ± 0.0036) cm −1 K −1 (buckled zones) for the E g mode (at 152 cm −1 ) by temperature-dependent Raman spectra. More intriguingly, all the samples exhibit biaxial strain-mediated FM behaviors at RT, which is also confirmed by theoretical investigation. Our study suggests that strain engineering is an effective approach to mediate magnetic properties of 2D materials, thereby opening an alternative way for "straintronic" and spintronic applications.ReS 2 thin films (thickness ≈ 60 nm; Figure S1, Supporting Information) with a residual compressive strain can remain flat in ambient environment for days or months, and then could Buckling-driven delamination of thin films on rigid substrates is frequently observed, which leads to deterioration or failure of the film-based devices. However, it is observed for the first-time that web buckles could enhance room-temperature ferromagnetism in PAD-grown ReS 2 thin films. Here, room-temperature ferromagnetic ReS 2 thin films with web buckles are prepared by polymer-assisted deposition (PAD) for the first time. The morphology and crystalline structure of the samples are characterized ...

Dental caries are the most prevalent chronic infections in the oral cavity, and Streptococcus mutans acts as the main cariogenic bacterial species. Antibacterial quaternary ammonium compounds (QAs) have been developed to preveFnt or treat dental caries. However, there is no report on the tolerance of S. mutans to QAs. In this study, we investigated the development of S. mutans persistence induced by a novel dental caries defensive agent, dimethylaminododecyl methacrylate (DMADDM), for the first time. Typical biphasic killing kinetics for persisters were observed in both S. mutans planktonic and biofilm cultures challenged by DMADDM at concentrations of 20 and 200 μg·mL−1, respectively. The persisters tolerated six other antibiotics with different antibacterial mechanisms, while only daptomycin and vancomycin could slightly reduce the persister numbers in planktonic cultures. The distribution of persisters in DMADDM-treated biofilms was similar to that in the untreated control, except that the total biomass and biofilm height were significantly reduced. A higher exopolysaccharides (EPS):bacteria ratio was observed in DMADDM-treated biofilms. Persisters in biofilms significantly upregulated gtf gene expression, indicating an increase in the bacteria’s ability to produce EPS and an elevated capability of cariogenic virulence. Carbon source metabolism was significantly reduced, as related metabolic genes were all downregulated in persisters. Concentrations of 0.1 mM, 1 mM and 10 mM of extra glucose significantly reduced the number of persisters both in planktonic and biofilm conditions. The formation of non-inheritable and multidrug tolerant persisters induced by DMADDM suggested that drug tolerance and new persistent eradication strategies should be considered for oral antibacterial agents.

Diluted magnetic semiconductors based on group‐IV materials are desirable for spintronic devices compatible with current silicon technology. In this work, amorphous Mn‐doped SiGe thin films are first fabricated on Ge substrates by radio frequency magnetron sputtering and then crystallized by rapid thermal annealing (RTA). After the RTA, the samples become ferromagnetic semiconductors, in which the Curie temperature increases with increasing Mn doping concentration and reaches 280 K with 5% Mn concentration. The data suggest that the ferromagnetism comes from the hole‐mediated process and is enhanced by the tensile strain in the SiGe crystals. Meanwhile, the Hall effect measurement up to 33 T to eliminate the influence of anomalous Hall effect reveals that the hole mobility of the annealed samples is greatly enhanced and the maximal value is ≈1000 cm2 V−1 s−1, owing to the tensile strain‐induced band structure modulation. The Mn‐doped SiGe thin films with high Curie temperature ferromagnetism and high hole mobility may provide a promising platform for semiconductor spintronics.

Oral squamous cell carcinoma (OSCC) is highly malignant and invasive, and current treatments are limited due to serious side effects and unsatisfactory outcomes. Here, we reported the terbium ions-doped hydroxyapatite...

Bacterial persistence has become a worldwide health problem due to its ability to cause the recalcitrance and relapse of infections. The existence of bacterial persistence and their possible mechanisms have been widely reported. However, the following regrowth of persister cells is not clear although the awakening of dormant surviving persisters is the key to reinitialize bacterial infection. In this study, we investigated the growth character and cariogenic virulence during the recovery of Streptococcus mutans drug-tolerant persister cells induced by a novel quaternary ammonium: dimethylaminododecyl methacrylate (DMADDM). A remarkable lag phase was observed in S. mutans persisters when regrew at the first 24 h compared to normal cells. During the entire recovery state, persisters are metabolically active to increase the production of both water-soluble and water-insoluble glucan. The shortage of cell number in persisters resulted in the decrease of lactic acid production, but persisters gradually recovered the normal acid production ability after 72 h. The up-regulated expression of gtf and vicR was in line with comDE circuit and consistent with the virulence change during the regrowth stage. Our findings proved that lethal dosages of DMADDM induced drugtolerant S. mutans persisters in biofilm, which had a prolonged lag phase and elevated cariogenic virulence during regrowth. The recovery and elevated virulence of persisters were regulated by quorum-sensing and VicRK pathway. This alarmed the elevated cariogenicity of persisters and highlighted the critical requirement for the drug-tolerance evaluation when developing new oral antimicrobial agents. To the best of our knowledge, we characterized the regrowth and cariogenic virulence variation of S. mutans persisters induced by quaternary ammonium for the first time. Our findings suggest that S. mutans

Bismuth tellurohalides have intrigued numerous interests for their novel Rashba splitting electronic structures with potential applications in spintronics and two‐dimensional (2D) optoelectronics. In this work, we have a detailed study of bulk BiTeCl and its exfoliated flakes using ultralow wavenumber Raman spectroscopy. We observe all BiTeCl characteristic Raman modes including the lowest wavenumber rigid layer in‐plane vibrational mode E32 at 19 cm−1. From 77 to 300 K, hardening of Raman modes are observed with sharpened profiles. Temperature coefficients of Raman modes except E32 are around −0.009 to −0.027 cm−1/K, showing the sensitive response of lattice vibrations to temperature, whereas E32 has a much smaller temperature coefficient of −0.004 cm−1/K and almost constant linewidth, similar to the behavior of shear mode of 2D materials. Furthermore, by using excitation lasers of 488, 514.5, 647, and 785 nm, we find that BiTeCl Raman modes are nondispersive, 2 characteristic in‐plane E modes are more pronounced for low‐energy lasers whereas out‐of‐plane A1 modes behave inversely, which could be related to the interband transitions. Our work provides valuable lattice vibrational and thermal information of BiTeCl for its integration into the emerging 2D nano devices as a promising polar layered material.

No abstract