Search

In this study, self-powered photodetectors (PDs) sensitive to ultraviolet (UV) and short-wavelength blue (SWB) light were developed using a ZnO/SrTiO3 heterojunction, created through the magnetron sputtering technique. The photoresponse of the ZnO/SrTiO3 PDs showed significant enhancement following an annealing process. Post-annealing, the response (R) value of the ZnO/SrTiO3 PDs was recorded at 0.7 mA W−1, indicating an increase of 3.5 times compared to the pre-annealed state. Additionally, the rejection ratio between 390 nm and 450 nm (R390 nm/R450 nm) improved markedly from 6.21 to 38.16, demonstrating enhanced UV-SWB spectral discrimination. The rise and decay times for the annealed devices were measured at 35 μs and 3.5 ms, respectively. The observed enhancements in the performance of ZnO/SrTiO3 PDs are primarily attributed to the improved crystal quality of ZnO and the optimized intrinsic defect structures within the ZnO films due to annealing. This led to a strengthened internal electric field, facilitating the efficient separation and movement of photogenerated charge carriers. The outcomes of this study offer significant insights for the design and production of self-powered UV-SWB photodetectors. [ABSTRACT FROM AUTHOR]

The rotor system during its operation is susceptible to various faults such as unbalance, rub-impact, crack, and misalignment, which usually induce the rotor system to exhibit nonlinear behavior. Some linear diagnosis methods are unable to extract nonlinear characteristics of the faulty rotor system. However, existing nonlinear fault diagnosis methods can describe the nonlinear characteristics but cannot quantitatively indicate the severity of rub-impact faults. To address this issue, this study combines the nonlinear output frequency response functions weighted contribution rate (WNOFRFs) and JS divergence to develop an improved fault diagnosis approach, WNOFRFs based on the JS divergence (WNOFRFs-JS). And a superior NOFRFs-associated index JSRm is developed to indicate the severity of faults. In addition, a sensitive factor is defined to evaluate the sensitivity of the index. The performance of this approach is verified by an established dynamic model and a rotor rub-impact experimental rig. The results prove the effectiveness and merits of this approach for the identification of rotor rub-impact. JSRm is especially sensitive to rub-impact and can also quantitatively detect the severity of faults. The present approach can accurately and quantitatively identify the rub-impact rotor system. These advantages enable the improved WNOFRFs to be applied in the fault diagnosis and condition monitoring of rotating machinery and even other nonlinear systems. [ABSTRACT FROM AUTHOR]

Y 2 O 3 nanoparticles (NPs) have become great promising products for numerous applications in nanoscience especially for biomedical application, therefore increasing the probability of human exposure and gaining wide attention in biosecurity. It is well known that rare earth (RE) materials are deposited in the bone and excreted very slowly. Nevertheless, the effect of Y 2 O 3 -based NPs on bone metabolism has not been exactly known yet. In the present study, the effects of Y 2 O 3 NPs on bone marrow stromal cells (BMSCs) and bone metabolism in mice after intravenous injection were studied. The results demonstrated that Y 2 O 3 NPs could be taken up into BMSCs and localized in acidifying intracellular lysosomes and underwent dissolution and transformation from Y 2 O 3 to YPO 4 , which could lead to a break in the intracellular phosphate balance and induce lysosomal- and mitochondrial-dependent apoptosis pathways. Furthermore, after being administered to mice, a higher concentration of yttrium occurred in bone, which caused the apoptosis of bone cells and induced the destruction of bone structure. However, the formation of a YPO 4 coating on the surface of Y 2 O 3 NPs by pretreatment of Y 2 O 3 NPs in lysosome-simulated body fluid could observably decrease the toxicity in vivo and in vitro. This study may be useful for practical application of Y 2 O 3 NPs in the biomedical field.