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TaxHf1–xC are promising candidates for many applications under harsh environments due to their unique properties. Up until now, low‐temperature densification is still a big challenge for these ceramics. Moreover, the effect of Ta:Hf ratio on microstructure development and mechanical behavior of the ceramics is not clear. In this work, highly dense TaxHf1−xC–SiC ceramics (x = 0.2, 0.4, 0.6, 0.8) were fabricated at 1700°C by a novel reactive hot‐pressing processing with 8 wt% Si as sintering aid, which present excellent mechanical properties. Fracture toughness of the ceramics is higher than 6.3 MPa·m1/2, with the highest toughness achieved in Ta0.6Hf0.4C–SiC (8.5 MPa·m1/2). With the increase of Ta content, hardness of the ceramics tends to increase, while the bending strength tends to decrease. The highest bending strength is achieved in Ta0.2Hf0.8C–SiC (637 MPa), and the highest hardness is achieved in Ta0.8Hf0.2C–SiC (17.6 GPa). This work lays the foundation for the composition design of TaxHf1−xC‐based ceramics and composites. [ABSTRACT FROM AUTHOR]

To improve the vibration performance of oil-lubricated tilting pad bearing systems, this paper investigates the impact of different structural parameters on the vibration reduction effect of piezoelectric actuators on flexible tilting pad bearings. Four sets of flexible tilting pad bearings were designed and manufactured, including a flexible hinge tilting pad bearing and three sets of double-layer spring-supported flexible tilting pad bearings with different parameters. The radial displacement of the bearing load pad was controlled to varying degrees using a piezoelectric actuator, and semi-active control experiments were conducted on the flexible tilting pad bearings. The experimental results show that appropriately reducing the radial clearance and the stiffness of the bearing's flexible structure can effectively suppress vibrations, enhance the vibration reduction effect of the piezoelectric actuation, and increase the stability of the bearing-rotor system. This study is of significant importance for the design of flexible tilting pad bearings and the vibration suppression of rotor systems. [ABSTRACT FROM AUTHOR]

In high-speed and heavy-load conditions, ordinary rigid tilting pad journal bearings experience significant contact stress at the pad pivot points, leading to severe pad deformation and increased wear. A flexible structure tilting pad bearing (FSTPB) is presented in this paper, using spring supports to replace the traditional pivot supports and flexible hinge supports. A theoretical calculation model for tilting pad radial journal bearings considering flexible structure deformation is established, and the impact of elastic deformation on the performance of the flexible structure tilting pad bearings is discussed. Based on theoretical research, vibration experiments on flexible tilting pad bearings under different loading conditions were conducted. The influence of various structural parameters on the vibration characteristics of the flexible tilting pad radial bearings was studied. The results indicate that, compared to ordinary tilting pad bearings, flexible structure tilting pad bearings exhibit excellent vibration reduction characteristics at high speeds. Reducing the bearing clearance, lowering the stiffness of the flexible structure, and increasing the offset angle of the flexible structure contribute to enhancing the operational stability of the bearing–rotor system. [ABSTRACT FROM AUTHOR]

Luminescent organic radicals, especially those with photoactivated circularly polarized luminescence (CPL) features, hold great significance for cutting‐edge optoelectronic applications, but their development still remains a challenge. In this study, we propose a novel strategy to achieve photoactivated CPL radicals by bonding two phosphine centers within an axial chiral system, yielding a compound of R/S‐5,5‐bis(diphenylphosphino)‐4,4′‐bibenzo[d][1,3]dioxole (R/S‐BDP). The photoactivated R/S‐BDP molecules in polymer matrix display a robust quantum yield of 19.8 % and a dissymmetry factor (glum) of 1.2×10−4, marking this work as the first example of photoactivated CPL radicals. Furthermore, the glum is improved to 1.0×10−2 by using a liquid crystal as host. Experimental and theoretical analyses reveal that R/S‐BDP molecules, endowed with double phosphine cores in axial chirality, offer a direct way for intramolecular electron transfer upon photoirradiation. This leads to the generation of radical ionic pairs, which subsequently trigger the donor‐acceptor arrangement through intermolecular electron transfer, thereby resulting in stable radical emission. The extended photoactivated BDP‐F exhibits a remarkably high quantum efficiency of 57.8%. Ultimately, the distinctive photo‐responsive CPL radical luminescence has been successfully used for information displays and anti‐counterfeiting. [ABSTRACT FROM AUTHOR]

Phosphorescent manganese(II) complexes with high photoluminescence quantum yields (PLQYs) and low cost exhibit great potential in organic light‐emitting diodes (OLEDs), information security, and X‐ray imaging. However, it is still a challenge to tune their emission colors. Herein, an effective strategy for engineering the phosphorescence colors of tetrahedral Mn(II) complexes through steric hindrance‐driven bond angle distortion is proposed. Modulating the steric hindrance between phosphine and benzofuran and varying the O─Mn─O bond angles allows these Mn(II) complexes to emit from 498 to 548 nm. Interestingly, these achiral single crystals of Mn(II) complexes exhibit significant circularly polarized luminescence signals due to symmetry breaking. Furthermore, high‐performance green OLEDs are achieved by using these Mn(II) complexes as dopants, providing a record‐high external quantum efficiency of 15.7%. These super‐duper results greatly inspire the development of multi‐color Mn(II) complexes and low‐cost Mn‐based devices. [ABSTRACT FROM AUTHOR]

Objective: The contribution of hypoxia to the pathophysiology of vascular smooth muscle cells (VSMCs) has not yet been fully elucidated. This study evaluated the effect of hypoxia on the phenotype and function of SMCs derived from the human normal great saphenous veins (NGSVs). Methods: Fifteen NGSV tissue samples were collected. SMCs were isolated and cultured. Proliferation, migration, adhesion, senescence, and the structure of cytoskeletal filaments in SMCs were observed. mRNA and protein expression of Bax, Bcl-2, caspase-3, matrix metalloproteinases (MMP)-2, MMP-9, tissue inhibitor of metalloproteinases (TIMP)-1, and TIMP-2 was detected by fluorescent quantitative polymerase chain reaction and immunoblotting in the cobalt chloride (CoCl2) and the control groups. Results: A decrease in the number of cytoskeletal filaments was observed. mRNA and protein expression of Bas and caspase-3 was significantly decreased, while the quantity of proliferation, migration, adhesion, senescence, and mRNA and protein expression of Bcl-2, MMP-2, MMP-9, TIMP-1, and TIMP-2 in SMCs in the CoCl2 group were significantly increased compared with the control group. Conclusion: Under hypoxic conditions, the phenotype and function of SMCs derived from the human NGSVs were dysregulated, suggesting that VSMCs switch from the contractile phenotype to the secretory or synthetic phenotype, and more dedifferentiate, resulting in extracellular matrix deposition and apoptotic decrease through the intrinsic pathway. [ABSTRACT FROM AUTHOR]