Multiple Energy Transfer Channels in Rare Earth Doped Multi-Exciton Emissive Perovskites.

Revealing the energy transfer (ET) process from excitons to rare earth ions in halide perovskites has great guiding value for designing optoelectronic materials. Here, the multiple ET channels in multi-exciton emissive Sb3+ /Nd3+ co-doped Cs2 ZrCl6 are explored to comprehend the ET processes. Förster-Dexter ET theory reveals that the sensitizer concentration rather than the overlap integral of the spectra plays the leading function in the comparison of the ET efficiency among multiple ET channels from the host self-trapped excitons (STEs) and dopant triplet STEs to Nd3+ ions. Besides, Sb3+ /Nd3+ co-doped Cs2 ZrCl6 enables varied color delivery and has great potential as anti-counterfeiting material. Under X-ray irradiation, Sb3+ /Nd3+ co-doped Cs2 ZrCl6 presents a high light yield of ≈13300 photons MeV-1 and promising X-ray imaging ability. This work provides new insight for investigating the ET efficiency among multiple ET processes and presents great potentiality of multi-exciton emissive perovskites in the fields of anti-counterfeiting and X-ray imaging.

Axial Compressive Properties of Fiber-Reinforced Polymer-High-Water Material-Polyvinyl Chloride Plastic Double-Wall Hollow Column.

To further enrich the side-filling structure system of goaf-retaining roadways and explore the compression reaction mechanism of the composite in the support environment of underground mine roadways, this paper introduces a double-wall hollow composite pier structure (FPRSC structure) that is composed of the fiber-reinforced polymer (FRP) composite and polyvinyl chloride plastic (PVC) as restraint materials and the infill material featured with a high water-to-powder ratio. A total of 16 circular specimens with a diameter and height of 100 mm were tested to explore the axial performance of the combined support structure. The main control variables in the present research included the water-to-cement ratio of the high-water material (e.g., 2:1, 3:1, and 4:1), the thickness of the FRP pipe (i.e., 6 mm and 3 mm), the inner diameter of the PVC pipe (i.e., 29 mm and 22 mm), as well as the thickness of the PVC pipe (1.5 mm and 5 mm). Test results showed that the high-water material was under triaxial stress due to the double-wall tube binding, and the bearing capacity of the composite was higher than that of the single material. Meanwhile, the FPRSC structure exhibited obvious strain-hardening characteristics when the infill material is under the combined constraints of double-wall hollow tubes. Moreover, the ratio of PVC-c, FRP-A, and high-water material with a water-cement ratio of 3:1 shows the best axial mechanical properties. The new composite pier structure with high toughness and strength has wide application prospects in the field of goaf retention in deep underground mines.

Online painting image clustering for the mental health of college art students based on improved CNN and SMOTE.

In modern education, mental health problems have become the focus and difficulty of students' education. Painting therapy has been integrated into the school's art education as an effective mental health intervention. Deep learning can automatically learn the image features and abstract the low-level image features into high-level features. However, traditional image classification models are prone to lose background information, resulting in poor adaptability of the classification model. Therefore, this article extracts the lost colour of painting images based on K-means clustering and proposes a painting style classification model based on an improved convolutional neural network (CNN), where a modified Synthetic Minority Oversampling Technique (SMOTE) is proposed to amplify the data. Then, the CNN network structure is optimized by adjusting the network's vertical depth and horizontal width. Finally, a new activation function, PPReLU, is proposed to suppress the excessive value of the positive part. The experimental results show that the proposed model has the highest accuracy in classifying painting image styles by comparing it with state-of-the-art methods, whose accuracy is up to 91.55%, which is 8.7% higher than that of traditional CNN.

The prediction of collective Economic development based on the PSO-LSTM model in smart agriculture.

Smart agriculture can promote the rural collective economy's resource coordination and market access through the Internet of Things and artificial intelligence technology and guarantee the collective economy's high-quality, sustainable development. The collective agricultural economy (CAE) is non-linear and uncertain due to regional weather, policy and other reasons. The traditional statistical regression model has low prediction accuracy and weak generalization ability on such issues. This article proposes a production prediction method using the particle swarm optimization-long short term memory (PSO-LSTM) model to predict CAE. Specifically, the LSTM method in the deep recurrent neural network is applied to predict the regional CAE. The PSO algorithm is utilized to optimize the model to improve global accuracy. The experimental results demonstrate that the PSO-LSTM method performs better than LSTM without parameter optimization and the traditional machine learning methods by comparing the RMSE and MAE evaluation index. This proves that the proposed model can provide detailed data references for the development of CAE.

The association between falls and anxiety among elderly Chinese individuals: The mediating roles of functional ability and social participation.

BACKGROUND: Elderly individuals who experience falls suffer from higher levels of anxiety because of physical or mental injury. This study examined the association between falls and anxiety among elderly Chinese individuals. It also explored the mediating roles of functional ability and social participation in the link between falls and anxiety. METHODS: The analytical sample included 8233 elderly people aged 60 and above, and prospective data were obtained from the Chinese Longitudinal Healthy Longevity Survey (CLHLS). Anxiety was evaluated by a 7-item Generalized Anxiety Disorder (GAD-7) scale, and falls were determined by self-report. The association between falls and anxiety was assessed by linear regression. Mediation analysis was used to explore the potential mediating roles of functional ability and social participation on the association between falls and anxiety. RESULTS: Suffering falls predicted higher anxiety levels among elderly individuals (B = 0.608, 95% CI: 0.471, 0.746). Functional ability and social participation play partial mediating roles in the association between falls and anxiety, and the mediating effects were 0.036 (95% CI: 0.020, 0.058) and 0.005 (95% CI: 0.003, 0.014), respectively. The serial mediating effect of functional ability and social participation on the association between falls and anxiety was 0.003 (95% CI: 0.002, 0.005). LIMITATIONS: This study is based upon cross-sectional data, which limit inferring causality. CONCLUSIONS: This study suggests that policy-makers should explore how to encourage elderly individuals who experience falls to restore functional ability and participate in appropriate social activities to alleviate anxiety.

Simultaneous Enhancement of Photoluminescence and Stability of CsPbCl3 Perovskite Enabled by Titanium Ion Dopant.

The application of CsPbCl3 perovskite is limited by the low photoluminescence quantum yield (PLQY), weak luminescence, and unpromising stability. Doping impurity ions has been considered as an effective strategy to tune the optoelectronic performances of perovskite. In this work, heterovalent Ti3+ ions are successfully doped into CsPbCl3 nanocrystals. It is found that Ti3+ ion doping could effectively improve the photoluminescence (PL) performance of CsPbCl3 nanocrystals. Density functional theory (DFT) calculations reveal that Ti3+ ions could introduce more band-edge states around the conduction band minimum of CsPbCl3, which is conducive to release electrons into conduction band. Furthermore, Ti3+ ion doping could inhibit the Cl vacancy concentration in CsPbCl3 and prevent the in-gap state caused by Cl vacancy. Notably, the stability of CsPbCl3 perovskite is greatly improved through Ti3+ ion doping. This work provides a new perspective for improving the optoelectronic properties of all-inorganic perovskites through heterovalent metal ion doping.

The evolution trend of availability of China's community-based care services and its impact on the cognitive function of elderly people: 2008-2018.

BACKGROUND: To address the challenge of the aging population, community-based care services (CBCS) have been developed rapidly in China as a new way of satisfying the needs of elderly people. Few studies have described the evolution trend of availability of CBCS in rural and urban areas and evaluated their effectiveness. This study aims to show the availability of China's CBCS and further analyze the effect of the CBCS on the cognitive function of elderly people. METHODS: Longitudinal analysis was performed using data from the 2008 to 2018 Chinese Longitudinal Healthy Longevity Survey (CLHLS). A total of 23937 observations from 8421 elderly people were included in the study. The Chinese version of the Mini-Mental State Examination (MMSE) was used to assess cognitive function. We aggregated similar CBCS to generate three binary variable categories (daily life support, emotional comfort and entertainment services, medical support and health services) indicating the availability of CBCS (1 = yes, 0 = no). Multilevel growth models were employed to estimate the association between CBCS and cognitive function while adjusting for many demographic and socioeconomic characteristics. RESULTS: The availability of CBCS increased a lot from 2008 to 2018 in China. Although the availability of CBCS in urban areas was higher than that in rural areas in 2008, by 2018 the gap narrowed significantly. Emotional comfort and entertainment services (B = 0.331, 95% CI = 0.090 to 0.572) and medical support and health services (B = 1.041, 95% CI = 0.854 to 1.228) were significantly and positively associated with cognitive function after adjusting for the covariates. CONCLUSION: There was a significant increase in the availability of CBCS from 2008 to 2018 in China. This study sheds light on the positive correlation between CBCS and cognitive function among Chinese elderly individuals. The results suggest that policymakers should pay more attention to the development of CBCS and the equity of the supply of CBCS in urban and rural areas.

The Association between Widowhood and Cognitive Function among Chinese Elderly People: Do Gender and Widowhood Duration Make a Difference?

Few studies have examined the effects of widowhood on cognitive function in Chinese elderly individuals. We conducted a longitudinal study to assess the association between widowhood and cognitive function and further explored gender differences in this association and the impact of widowhood duration. The analytical sample consisted of 5872 Chinese elderly people who participated in the Chinese Longitudinal Healthy Longevity Survey (CLHLS) and were followed up from 2005 to 2014. We used the Chinese version of the Mini-Mental State Examination (MMSE) to assess cognitive function. Widowhood duration was calculated from the self-reported year at which the spouse passed away. Multilevel growth models were employed to estimate the association between widowhood and cognitive function while adjusting for many demographic and socioeconomic characteristics. Widowhood status was associated with cognitive decline among Chinese elderly individuals after adjusting for covariates (B = -0.440, 95% CI -0.727 to -0.152), and this association was only statistically significant among men (B = -0.722, 95% CI -1.104 to -0.339). Being widowed for 5 years or less (B = -0.606, 95% CI -1.112 to -0.100), 16-20 years (B = -0.937, 95% CI -1.685 to -0.190), and 21+ years (B = -1.401, 95% CI -1.967 to -0.834) predicted worse cognitive function in men, while being widowed for more than 21+ years (B = -0.655, 95% CI -1.186 to -0.124) was associated with cognitive decline in women. More attention should be directed towards widowed men and long-term widowed elderly individuals.

Effects of municipal sewage sludge stabilized by fly ash on the growth of Manilagrass and transfer of heavy metals.

A greenhouse experiment was carried out to evaluate the feasibility of using an artificial soil for cultivation of Manilagrass. The transfer and transformation of heavy metals in the artificial soil-Manilagrass system were discussed at the same time. The results showed that fly ash-sludge indicated a positive effect on the growth of Manilagrass. The pots with 14% sludge and 6% fly ash mixture had the highest yield and nutrient concentrations of Manilagrass. With the increasing application of coal fly ash, the concentrations of Ni, Zn, Mn, Sb and Cu in Manilagrass decreased significantly, while Pb, V and Ti increased. Otherwise, the concentrations of Cd, As, Cr, Co, and Fe did not show a remarkable change. Except for Sb, the values of bio-concentration factor of heavy metals in Manilagrass were all below 1.0 after treated by the fly ash-sludge treatment, decreased as Sb>Ni>Zn>Cu>Pb>Mn>Co=Cr>Cd>Fe=V>Ti>As in an average for all treatments. Compared to the contrast check, the proportions of heavy metals in exchangeable, reducible and oxidizable fractions increased. Manilagrass could be used to reduce the eco-toxicity and bioavailability of Ti, V, Mn, Co, Cr and Cd in fly ash-sludge amended soil.