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Thermal conductivity κ (T) of single-crystal CVD diamond lightly doped (about 3 ppm) with nitrogen has been measured at temperatures from 5.7 to 410 K. The sample was carefully characterized by optical absorption and photoluminescence spectroscopy for the presence of impurities. Nine different optically active defects related with nitrogen, hydrogen, and silicon impurities have been identified and quantified. This pink-tint crystal showed a high thermal conductivity of 24.0 ± 0.5 W cm − 1 K − 1 at room temperature, which is very close to the highest value ever measured at about 25 W cm − 1 K − 1 for diamonds of natural isotopic composition. At the same time, the κ (T) of the crystal showed strong suppression > --> 10 % at temperatures 6 < T < 120 K with a maximum decrease of 2.7 times at ≈ 40 K compared to high purity diamonds. This behavior of the conductivity is attributed to a phonon scattering by charge carriers bound to nitrogen-related impurity centers, which is ineffective, however, at room and higher temperatures. The κ (T) has been calculated within the model based on the Callaway theory taking into account the elastic phonon scattering off charge carriers (holes and electrons) in the ground states of doping centers, and a very good agreement between the measured and theoretical data has been achieved. The model also gives a good approximation to the experimental data for κ (T) given in the literature for synthetic and natural single-crystal diamonds. [ABSTRACT FROM AUTHOR]

Hyperbolic phonon polaritons in optically uniaxial hexagonal boron nitride (hBN) have shown considerable potential for manipulating light on the deep‐subwavelength scale, but the inherent in‐plane isotropy of hBN hinders their further application in planar polariton meta‐optics. Engineering these polaritons to achieve ultraconfined in‐plane anisotropic propagation is of scientific significance for facilitating light–matter interactions toward an extreme scale. Here, the polariton features are systematically investigated in a vertically stacked van der Waals heterostructure consisting of hBN and tellurium (Te), a highly birefringent van der Waals crystal in the mid‐infrared region. Polaritons in this heterostructure exhibit Te‐thickness‐dependent anisotropic dispersion, and the configurable in‐plane anisotropy and enhanced field confinement are experimentally demonstrated using scanning near‐field optical microscopy. It is concluded that these findings contribute to the fundamental understanding of anisotropic polaritons in hBN van der Waals heterostructures, providing a practical avenue for effectively engineering anisotropic PhPs in an intrinsically isotropic van der Waals material. [ABSTRACT FROM AUTHOR]

Transparent polysiloxane elastomers with good self-healing and reprocessing abilities have attracted significant attention in the field of artificial skin and flexible displays. Herein, we propose a simple one-pot method to fabricate a room temperature self-healable polysiloxane elastomer (HPDMS) by introducing dynamic and reversible imine bonds and boroxine into polydimethylsiloxane (PDMS) networks. The presence of imine bonds and boroxine is proved by FT−IR and NMR spectra. The obtained HPDMS elastomer is highly transparent with a transmittance of up to 80%. The TGA results demonstrated that the HPDMS elastomer has good heat resistance and can be used in a wide temperature range. A lower glass transition temperature (Tg, −127.4 °C) was obtained and revealed that the elastomer is highly flexible at room temperature. Because of the reformation of dynamic reversible imine bonds and boroxine, the HPDMS elastomers exhibited excellent autonomous self-healing properties. After healing for 3 h, the self-healing efficiency of HPDMS reached 96.3% at room temperature. Moreover, the elastomers can be repeatedly reprocessed multiple times under milder conditions. This work provides a simple but effective method to prepare transparent self-healable and reprocessable polysiloxane elastomers. [ABSTRACT FROM AUTHOR]

Theoretically, the stronger electronegativity of N compared to that of P suggests that N-doped FeP4 could reduce the adsorption energy of hydrogen, potentially enhancing the kinetics of the hydrogen evolution reaction (HER) and improving its electrochemical characteristics. Experimentally, a three-dimensional (3D) porous dodecahedron N-doped FeP4 nanoparticle array catalyst developed on carbon cloth (CC) was investigated. The synthesized N-doped FeP4/CC nanoparticle electrocatalysts demonstrated satisfactory HER performance. These electrocatalysts showed a current density (J) of 10 mA/cm–2 at an overvoltage of 87 mV in a 0.5 M H2SO4 solution, indicating that the electronically modified FeP4 (N-FeP4/CC) catalyst exhibited superior HER activity. Additionally, the overpotential for the N-doped FeP4/CC nanoparticle catalyst was 347 mV for HER in simulated seawater solution (0.5 M H2SO4 + 0.5 M NaCl), demonstrating the exceptional catalytic activity of the N-doped FeP4/CC nanoparticle catalyst. Density functional theory (DFT) calculations showed that N doping could synergistically improve the Gibbs free energy of hydrogen adsorption (ΔGH*) of FeP4 (−0.29 eV), which was lower than that of undoped FeP4 (0.41 eV). This supports the theoretical proposition that modifying the electronic structure can enhance the electrolysis hydrodynamics and catalytic performance, aligning with experimental findings. This study may provide a strategy for optimizing the electronic structure of seawater splitting. [ABSTRACT FROM AUTHOR]

Heterojunction semiconductors have been extensively applied in various optoelectronic devices due to their unique carrier transport characteristics. However, it is still a challenge to construct heterojunctions based on colloidal quantum dots (CQDs) due to stress and lattice mismatch. Herein, HgSe/CsPbBrxI3−x heterojunctions with type I band alignment are acquired that are derived from minor lattice mismatch (~1.5%) via tuning the ratio of Br and I in halide perovskite. Meanwhile, HgSe CQDs with oleylamine ligands can been exchanged with a halide perovskite precursor, acquiring a smooth and compact quantum dot film. The photoconductive detector based on HgSe/CsPbBrxI3−x heterojunction presents a distinct photoelectric response under an incident light of 630 nm. The work provides a promising strategy to construct CQD-based heterojunctions, simultaneously achieving inorganic ligand exchange, which paves the way to obtain high-performance photodetectors based on CQD heterojunction films. [ABSTRACT FROM AUTHOR]

Background The fat mass and obesity-associated protein (FTO) is an RNA demethylase that contributes to several physiological processes. Nonetheless, the impact of FTO on bone remodeling in the midpalatal suture while undergoing rapid maxillary expansion (RME) remains unclear. Methods First, to explore the expression of FTO in the midpalatal suture during RME, six rats were randomly divided into two groups: Expansion group and Sham group (springs without being activated). Then, suture mesenchymal stem cells (SuSCs) were isolated as in vitro model. The expression of FTO was knocked down by small interfering RNA to study the effect of FTO on the osteogenic differentiation of SuSCs. Finally, to evaluate the function of FTO in the process of bone remodeling in the midpalatal suture, ten rats were randomly divided into two groups: FB23-2 group (10 μM, a small molecule inhibitor of FTO) and DMSO group (control). Results Increased arch width and higher expression of OCN and FTO in the midpalatal area were observed in expansion group (P  < .05). In the in vitro model, the mRNA expression levels of Runx2, Bmp2, Col1a1, Spp1, and Tnfrsf11b were decreased (P  < .05) upon knocking down FTO. Additionally, the protein levels of RUNX2 and OPN were also decreased (P  < 0.05). Adding FB23-2, a small-molecule inhibitor targeting FTO, to the medium of SuSCs caused a decrease in the mRNA expression levels of Runx2, Bmp2, Col1a1, Spp1, and Tnfrsf11b (P  < 0.05). There was a statistically significant difference in evaluating the expression of OCN and OPN on the palatal suture between the FB23-2 and DMSO groups (P  < .05). Limitation The molecular mechanisms by which FTO regulates SuSCs osteogenesis remain to be elucidated. The FTO conditional knock out mouse model can be established to further elucidate the role of FTO during RME. Conclusion FTO contributes to the osteogenic differentiation of SuSCs and plays a promoting role in midpalatal suture bone remodeling during the RME. [ABSTRACT FROM AUTHOR]

With increasing demand for scratch-resistant flexible electronics, the development of transparent coatings with good scratch resistance and self-healing properties has emerged as a key research topic. In this study, a high-strength self-healing poly(urethane – urea) (PUU)-based nanocomposite coating was prepared by introducing functionalized nanodiamond (ND) into a PUU matrix via solution blending. The PUU matrix had hard-segment repeating units and was constructed using isophorone diamine and isophorone isocyanate. The ND particles were modified using a silane coupling agent, 3-aminopropyltriethoxysilane, to obtain well-dispersed KH-ND nanoparticles. KH-ND promoted microphase separation in the PU matrix, inducing the formation of dense and homogeneous hard domains that dissipated stress, prevented further crack development, and improved the mechanical properties and scratch resistance of the coating. In addition, the coating exhibited excellent self-healing properties. Fourier-transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy were used to characterize the self-healing and hardening mechanisms of the coating. The environmentally friendly PUU/KH-ND coating is easy to prepare and has broad application prospects in transparent and anti-scratch coatings for flexible electronics, automobiles, and home appliances. [ABSTRACT FROM AUTHOR]