The coarsening characteristics of Al3Sc precipitates in Al-5Mg-0.3Sc (in wt.%) alloys annealed at 300–450 °C were studied using transmission electron microscope (TEM), with the annealing temperature ...of the alloy found to have a significant influence on its coarsening rate. Increasing the temperature range from 300 to 450 °C resulted in the coarsening rate increasing by an order of magnitude for every 50 °C. Experimental precipitation results were well correlated with theoretical results produced using a KV model. The diffusion activation energy of the Al3Sc precipitates was shown to be around 189 ± 8 kJ mol−1, with the precipitates exhibiting good coherency with the aluminum matrix, even after being annealed at 300–450 °C for 168 h.
•The critical size for loss of coherency increased in the presence of Mg.•The coarsening rate of Al3Sc precipitates was measured.•The diffusion activation energy for Al3Sc precipitates was 189 ± 8 kJ mol−1.
Mental health concerns have become a common problem among college students. Studies have shown that college students have a higher depression rate than the general population. The effect of campus ...green spaces on college students’ mental health has been widely studied. However, the internal mechanism of campus green spaces affecting college students’ mental health is not fully discussed. The data came from a cross-sectional survey of 45 Chinese universities. This paper discussed the relationship between campus green spaces, academic achievement, and college students’ mental health. Depending on gender, college students displayed different levels of mental health. The prevalence of depression among female students was higher than among male students. The effect of campus green spaces on mental health was higher in males than females, while the effect of campus green spaces on academic achievement had little gender difference. We call for the construction, improvement, and renewal of campus green spaces in the future not only to meet the needs of different gender groups, but also to pay more attention to the needs of female college students and improve the differences in mental health, so as to improve the mental health of the whole college student population.
Mercury (Hg) is the most toxic heavy metal and can lead to severe irreversible injury to human health and serious pollution. It is of great significance to explore precise and facile detection ...methods for preventing environmental pollution and ecological problems. Herein, silicon-doped carbon dots (Si-CDs) with bright blue emission were fabricated and employed as a fluorescent probe for the quantitative detection of Hg2+. Possessing high photostability and excellent solubility in water, the Si-CDs exhibit an efficient response to Hg2+ by a “on–off” switching strategy. As a sensing probe, Si-CDs exhibit a good linear relationship with Hg2+ in the concentration range of 0.008–0.4 μM with a limit of detection of 33 nM. Moreover, the proposed method was successfully applied to monitor Hg2+ in different real water samples with satisfactory recoveries of 96.2%–99.5%, demonstrating their excellent accuracy and environment tolerance. Notably, the Si-CD powder obtained by lyophilization can visualize latent fingerprints with second-level details. The results serve to underscore how CDs designed for multiple applications in detection can be exploited to provide promising multi-functional fluorescent materials.
Overuse of antibiotics posed a global threat to human health and the ecological environment. Efficient detection and control of antibiotic pollution demand novel sensory materials. Here, a ...dual-luminescent material FS@UIO66 was successfully synthesized by encapsulating fluorescent molecules (fluorescein sodium, FS) in UIO66 based on the in-situ encapsulation method. We found that the dual emission peaks of FS@UIO66 at 369 and 515 nm can be sensitively and synchronously quenched by tetracycline (TET). Interestingly, these two peak intensities were switched anisotropically by levofloxacin (LEV), in which the signal at 515 nm was enhanced. Photophysical analysis revealed that there may exist a competition and replenishment mechanism in the sensing processes. The ratiometric fluorescent feature was employed for rapid detection of TET and LEV, with detection limits of 0.2444 μM and 0.2808 μM for TET and LEV, respectively. The superior sensitivity, high selectivity, and excellent recyclability of FS@UIO66 in sensing TET and LEV were demonstrated in this work. In addition, TET and LEV were also successfully detected by FS@UIO66 in water from real water environment. The results indicate that FS@UIO66 composites are favorable for TET and LEV detection, presenting a great sensing platform for antibiotic detection.
Display omitted
•A dual-emission luminescent probe was synthesized by in-situ encapsulation.•We reported a ratiometric fluorescent platform for tetracycline and levofloxacin.•The platform has superior sensitivity, high selectivity, and a low detection limit.
•Bearing acceleration and displacement of outer and inner ring analysis under vibration excitation.•Bearing dynamic response with ring defect under vibration excitation.•Bearing failure mechanism ...analysis under vibration excitation.•Bearing dynamic test rig of simulating and withstanding vibration excitation was designed and built.
The dynamic response of bearings under vibration excitation environment is an important theoretical basis for studying the occurrence and extension analysis of abnormal bearing failures in engineering, the influence of vibration excitation environment on acceleration, displacement and stiffness signal data under different bearing conditions and working conditions is analyzed in this paper. Firstly, a vertical bearing test bench, which can simulate and withstand vibration excitation environment is built, and the measured vibration signals of the tested bearing are analyzed to obtain the changes of bearing dynamic parameters (acceleration, orbit of bearing center and stiffness) under different working conditions. Secondly, these parameters variation of the normal bearing and the bearing with outer raceway fault under the presence/absence of vibration excitation environment are compared respectively. Finally, the influence of the vibration excitation on bearing failure mechanism is analyzed. The results show that the vibration excitation can significantly increase the acceleration and axis trajectory of the bearing, and the maximum can be increased by 7 times. and the stiffness of the bearing is significantly reduced, and the maximum can be reduced by 60 %, which accelerates the degradation rate of the bearing raceway surface and may lead to early failure of the bearing. The results of this paper can provide data support for the abnormal failure analysis of bearings under periodic excitation environment in practical engineering.
Considering the effects of climate zones on building energy, a numerical study was conducted to investigate the energy consumption of a bedroom task/ambient air conditioning (TAC) in different ...climate zones. In this study, a PMV-based operating strategy of TAC was proposed to dynamically control energy consumption during night. According to this operating objective, the TAC was operated at two conventional operating modes: variable supply air temperature mode (VAT) and variable supply air flow rate mode (VAF). It's found that compared to VAF mode, VAT mode help reduce energy consumption by no less than 10% in Beijing, 19% in Shanghai and 18% in Guangzhou. To further reduce operating power, the variable air flow rate and air temperature mode based on lowest energy consumption (VFT-LowE) was adopted to optimize the operating of TAC, and the results show that compared to VAT, VFT-LowE mode can save energy by up to 6.5% in Guangzhou. Moreover, the highest energy saving potential was also evaluated showing a highest energy saving per night of 403 kJ in Beijing, and around 1100 kJ in Shanghai and Guangzhou. It's also indicated that the optimized operating mode has the largest energy saving potential in climate zones with higher air temperature.
•A CFD study was conducted on TAC system applied in different climate zones.•RSM method was used to predict energy consumption of TAC system.•The TAC was operated under PMV-based strategy with two modes: VAT and VAF.•Compared to VAF mode, VAT mode helped reduce energy consumption.•The TAC was optimized by VFT-LowE mode which had the lowest energy consumption.
Low-order features based on convolution kernel are easy to be distorted when encountering dramatic view angle transformation and atmospheric scattering in remote sensing (RS) images. To address this ...concern, this article first proposes to operate semantic segmentation of RS images based on the high-order information, which can represent the relative relationship of low-order features and is robust and stable when suffering feature distortion. Besides, semantic decouples have recently been well researched and have achieved significant improvement in image understanding. Thus, in this article, a high-order semantic decoupling network (HSDN) is proposed to disentangle features by semantics based on high-order features. Specifically, HSDN first represents each pixel by calculating the pixel-level affinity as a high-order feature and then clusters these pixels into different semantics. Afterward, an attention-like mask generation module is designed for both intra-semantic and inter-semantic groups, leading to three kinds of masks, including the semantic decoupling mask (SDM), which utilizes each high-order cluster centroid as a mask to compact features intracluster and expand different interclusters, so as to improve semantic disentangle performance to a better extent; semantic enhancement mask (SEM), which records pixel-level relative correlation within a class to sufficiently exploit high-order features and could enhance feature robustness; and boundary supplementary mask (BSM), which aims to process borderline pixels to reduce cluster errors. Finally, by applying masks on pixels both within classes and on borderlines, semantic decoupled features are generated and concatenated to realize segmentation. The quantitative and qualitative experiments are conducted on two large-scale fine-resolution RS image datasets to demonstrate the significant performance of adopting high-order representation. Besides, we also implement numerous experiments to validate the effectiveness of the proposed semantic decouple framework in dealing with complicated and distortion-prone RS image segmentation tasks.
MicroRNA (miR)-224-5p has been reported to be associated with multiple types of cancer. However, its biological role and underlying mechanism in hepatocellular carcinoma (HCC) has yet to be fully ...elucidated. The aim of the present study was to investigate whether miR-224-5p mRNA expression level was increased in hepatocellular carcinoma and whether it was associated with poor prognosis. Decreased mRNA expression level of miR-224-5p was shown to suppress liver cancer cell migration, invasion and epithelial-mesenchymal transition (EMT). Mechanistically, E2F1 was found to regulate miR-224-5p expression by binding to its promoter region. Melanoregulin (MREG) was identified as the direct target of miR-224-5p by searching the TargetScan, miRDB and StarBase databases. Overexpression of MREG could attenuate liver cancer cell migration, invasion and EMT. Rescue experiments further confirmed that MREG was associated with the regulation of miR-224-5p in liver cancer. In addition, the E2F1/miR-224-5p axis was shown to promote liver cancer cell migration, invasion and EMT by regulating MREG expression. These results suggested that E2F1-induced upregulation of miR-224-5p may serve an important role in MREG-induced liver cancer cell migration, invasion and EMT, and highlights the regulatory function of miR-224-5p in liver cancer. Therefore, the E2F1/miR-224-5p/MREG axis may provide a theoretical basis for the clinical treatment of hepatocellular carcinoma.
Background and aims Considering the global demands in sustaining agriculture, use of organic amendments is gradually increasing. An improved understanding of the biological process is essential to ...evaluate the performance of organic amendments on agro-ecosystem. Methods Soils subjected to different fertilization regimes were collected from a field experiment. Microbial community compositions are assessed with 16S and ITS rRNA gene sequencing and subsequent bioinformatics analysis. Microbial functions are characterized with the geometric mean of the assayed enzyme activities (GMea) and the microbial carbon-use efficiency:nitrogen-use efficiency ratio (CUE:NUE). Results Compared with the chemically fertilized soil, the GMea significantly increased in organically amended soils. In contrast, the CUE:NUE was highest in chemically treated soil. These changes of microbial functional indicators were associated with shifts in the bacterial and not the fungal community composition, despite the fact that both the bacterial and fungal community compositions were significantly affected by the fertilization regimes. The abundances of specific soil bacterial taxa, especially the genera Luteimonas and Gemmatimona, were enriched by organic amendments. Soil organic carbon emerged as the major determinant of the bacterial community composition. Conclusions Soil microbial activities and nutrient-use efficiencies were dramatically changed along with the alteration of bacterial community composition. Relatively greater abundance of Luteimonas and Gemmatimona taxa in soils might be useful indicators for soil amelioration. Our research could be helpful to provide better strategies for the maintenance of soil fertility.
PDF
