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基于Timoshenko梁变形理论研究多孔功能梯度材料梁的非线性自由振动问题。针对多孔功能梯度材料梁的孔隙均匀分布和孔隙线性分布2种形式, 根据广义Hamilton原理推导多孔功能梯度材料Timoshenko梁的非线性自由振动的控制微分方程组并对方程组进行无量纲化。采用微分变换法(DTM)对各种边界条件下的控制微分方程组进行变换, 得到等价代数特征方程。计算了多孔功能梯度材料Timoshenko梁在固支-固支(C-C)、固支-简支(C-S)、简支-简支(S-S)和固支-自由(C-F)4种边界条件下非线性横向自由振动的无量纲固有频率比值。将其退化为无孔隙功能梯度材料Timoshenko梁的非线性自由振动后, 所得非线性无量纲固有频率比值与已有文献的计算结果进行对照, 验证了文中方法的有效性和正确性, 讨论了边界条件、孔隙率、细长比和梯度指数对多孔功能梯度材料Timoshenko梁非线性无量纲固有频率比值的影响。

To improve the water resources carrying capacity of the Xiangjiang River Basin and achieve sustainable development, this article evaluates and predicts the Xiangjiang River Basin's water resources carrying capacity level based on county-level units. This article takes 44 county-level units in the Xiangjiang River Basin as the evaluation target, selects TOPSIS and the entropy weight method to determine weights, calculates the water resources carrying capacity level of the evaluation sample, uses a BP neural network model to calculate the predicted water resources carrying capacity level for the next 5 years, and adds the GIS method for spatiotemporal analysis.(1) The water resources carrying capacity of the Xiangjiang River Basin has remained relatively stable for a long period, with overloaded areas being the majority. (2) There are relatively significant spatial differences in the carrying capacity of water resources: Zixing City, located upstream of the tributary, is far ahead due to its possession of the Dongjiang Reservoir; the water resources carrying capacity in the middle and lower reaches (northern region) is generally higher than that in the upper reaches (southern region). (3) According to the BP neural network model prediction, the water resources carrying capacity of the Xiangjiang River Basin will maintain a stable development trend in 2022, while areas such as Changsha and Zixing City will be in a critical state, and other counties and cities will be in an overloaded state.This study has important references value for the evaluation and early warning work of the Xiangjiang River Basin and related research, providing a scientific and systematic evaluation method and providing strong support for water resource management and planning in Hunan Province and other regions. [ABSTRACT FROM AUTHOR]

Currently, epoxy resin (EP) is widely used in various fields, but its flammability greatly limits the wider application of EP. In recent years, additive flame retardants have been widely used to enhance the flame retardancy of EPs, but poor resistance to weather and aging is a prevalent issue encountered with additive flame retardants. To improve the weather fastness, researchers have successfully created and synthesized EP molecules that possess a combined effect of P, N, and B. The results demonstrate a significant enhancement in the mechanical properties of materials containing 20% BVN/10% VPD/EP compared with those of pure EP. 20% BVN/20% VPD/EP exhibited a vertical combustion rating of V‐1 with a limiting oxygen index measuring at 29.8%. The flame retardant epoxy thermosets exhibited a notable decrease in both the maximum heat release rate and total heat release. The findings indicate that the inherent flame‐retardant properties of the P‐N‐B coacting EP are not only characterized by exceptional curing and flame retardancy but also by superior resistance to weathering and aging compared with the additive flame retardant. [ABSTRACT FROM AUTHOR]

The aim of this study was to elucidate the specific mechanism through which 7-difluoromethoxy-5,4'-dimethoxygenistein (DFMG) inhibits angiogenesis in atherosclerosis (AS) plaques, given its previously observed but poorly understood inhibitory effects. In vitro, a model using Human Umbilical Vein Endothelial (HUVEC-12) cells simulated the initial lesion in the atherosclerotic pathological process, specifically oxidative stress injury, by exposing cells to 30 μmol/L LPC. Additionally, an AS mouse model was developed in ApoE knockout mice through a 16-week period of high-fat feeding. DFMG demonstrated a reduction in tubule quantities in the tube formation assay and neovascularization induced by oxidative stress-damaged endothelial cells in the chicken embryo chorioallantoic membrane assay. Furthermore, DFMG decreased lipid levels in the blood of ApoE knockout mice with AS, along with a decrease in atherosclerotic plaques and neovascularizations in the aortic arch and descending aorta of AS animal models. DFMG treatment upregulated microRNA140 (miR-140) expression and suppressed VEGF secretion in HUVEC-12 cells. These effects were counteracted by Toll-like receptor 4 (TLR4) overexpression in HUVEC-12 cells subjected to oxidative injury or in a mouse model of AS. Dual-luciferase reporter assays demonstrated that miR-140 directly targeted TLR4. Immunohistochemical assay findings indicated a significant inverse relationship between miR-140 expression and TLR4 expression in ApoE knockout mice subjected to a high-fat diet. The study observed a close association between DFMG inhibitory effects on angiogenesis and plaque stability in AS, and the inhibition of the TLR4/NF-κB/VEGF signaling pathway, negatively regulated by miR-140. [ABSTRACT FROM AUTHOR]

The breathtaking economic development put a heavy toll on ecology, especially on water pollution. Efficient water resource management has a long-term influence on the sustainable development of the economy and society. Economic development and ecology preservation are tangled together, and the growth of one is not possible without the other. Deep learning (DL) is ubiquitous in autonomous driving, medical imaging, speech recognition, etc. The spectacular success of deep learning comes from its power of richer representation of data. In view of the bright prospects of DL, this review comprehensively focuses on the development of DL applications in water resources management, water environment protection, and water ecology. First, the concept and modeling steps of DL are briefly introduced, including data preparation, algorithm selection, and model evaluation. Finally, the advantages and disadvantages of commonly used algorithms are analyzed according to their structures and mechanisms, and recommendations on the selection of DL algorithms for different studies, as well as prospects for the application and development of DL in water science are proposed. This review provides references for solving a wider range of water-related problems and brings further insights into the intelligent development of water science. [ABSTRACT FROM AUTHOR]

Biochar incorporation is a widespread approach for soil improvement and soil carbon sequestration. However, there have only been a few studies on the effects of large-scale biochar incorporation on the estuarine wetland soil. To assess the different rates and incorporation times of biochar effects on the soil carbon cycle, the effects and mechanisms of biochar actions on soil respiration and plant growth were clarified via an outdoor control experiment that analyzed the soil microbial activity and community structure of estuarine wetland soil. The results unconventionally showed that a higher rate (238.82 g·kg−1) of biochar incorporation achieved stimulated soil respiration compared to lower incorporation rates (9.14 g·kg−1, 23.89 g·kg−1, 47.79 g·kg−1 and 143.36 g·kg−1) and was 38.9%, −21.8%, and 6.23% higher than the soil respiration of the control on three incorporation months. The soil microbial biomass (45.54% in the higher rate of biochar incorporation soil than the control) and the activities of β-glucosidase enzymes (25.4% higher in the higher rate of biochar incorporation soil than the control) explained these differences in soil respiration. This phenomenon was confirmed to be a result of provoking the bacteria of a heterotroph or from a lower humification ability, which enhanced organic carbon degradation in a large amount of biochar incorporation soil. In conclusion, even large-scale biochar incorporation may introduce more stable carbon to the soil, and the carbon sink of estuarine wetland soil may weaken due to the greater carbon output generated in its specific soil microbial species. [ABSTRACT FROM AUTHOR]

In this work, we for the first time report photo-activated time-dependent color-changeable ultralong organic room temperature phosphorescence (UORTP) by co-doping derivatives (CN2BdBr and CN2BCzBr) of two phosphorescence units, H-benzo[f]indole (Bd) and 7H-benzo[c]carbazole (BCz). BCz is a newly reported phosphorescence unit. Two donor–acceptor (D–A) type derivatives (CNCzBCzBr and CN2BCzBr) were synthesized and their ultralong phosphorescence properties were studied in solution, the pure powder state and the PMMA film. In solution, both compounds are not ultralong phosphorescence active at room temperature but show an intense green afterglow at 77 K. Their pure powders cannot emit an afterglow at room temperature due to their high non-radiation rate but give out a yellow afterglow at 77 K because enhanced intermolecular interactions in the aggregated state reduce the energy level of triplet excitons and lead to a red shift. Amazingly, both compounds demonstrate photo-activated green UORTP in the PMMA film and their afterglow lifetimes are longer than that of CN2BdBr. ESR spectra verify that ultralong phosphorescence is activated and enhanced due to the consumption of oxygen in the PMMA film, which is similar to Bd and its derivatives. Finally, CN2BCzBr and CN2BdBr are co-doped into the PMMA film and photo-activated time-dependent color changeable UORTP is successfully achieved because the afterglow lifetime difference is large enough and two kinds of phosphorescence units can function independently. To our best knowledge, we for the first time propose a co-doping strategy and realize unique photo-activated time-dependent color-changeable UORTP. [ABSTRACT FROM AUTHOR]

Ecologically fragile areas in China account for more than half of its land area. Performing early warning assessments and trend analyses of resource and environment carrying capacity in ecologically fragile areas can lay a scientific foundation for ecological conservation in the areas. Based on the connotation of resource and environment carrying capacity, an early warning index system of resource and environment carrying capacity in Altay prefecture was constructed from the three aspects natural resource carrying capacity, eco-environment carrying capacity, and economic and social support capacity. The grey relational projection method model was used to analyze the current alarm situation of the resource and environment carrying capacity in Altay prefecture from 2011 to 2020, and then the back propagation (BP) neural network and a mathematical statistics software were used to predict the evolution of the alarm situation of the resource and environment carrying capacity in Altay prefecture from 2021 to 2025. The results demonstrated that (1) the natural resource carrying capacity subsystem was the main system of the development of the resource and environment carrying capacity in Altay prefecture, and its impact on the resource and environment carrying capacity in Altay prefecture was greater than the eco-environment carrying capacity and economic and social support capacity; (2) the resource and environmental carrying capacity of Altay prefecture showed a slight upward trend from 2011 to 2020, although the range was constrained and the level of warning remained "moderate warning". A spatial pattern of "weak in the middle, strong in the two poles" was exhibited by the warning scenario about the carrying capacity of each county and city. Except for the warning of Habahe County and Qinghe County, where the warning was slightly worse than that in 2020, the warning of resource and environment carrying capacity in Altay prefecture and other counties and cities would show a trend of fluctuation and decline from 2021 to 2025. However, the degree of alarm did not change substantially and remained at the level of "moderate warning"; (3) the main factors restricting the mitigation of the warning of resource and environment carrying capacity in Altay prefecture included a low soil fertility index, a small total reservoir capacity, low per capita mineral resource reserves, a low water resource development and utilization rate, a low comprehensive utilization rate of industrial solid waste, and a low land output rate. [ABSTRACT FROM AUTHOR]

The inland and estuary wetlands that characterized by different natural environment perform distinctly in soil carbon (C) sink. It was deemed that estuary wetland has a higher organic C accumulation rate than inland wetland, due to its higher primary production and tidal organics input, thus having higher organic C sink capacity. While from CO2 budge in view, whether does the large organic input from tide restrict CO2 sequestration capacity of estuary wetland has not been discussed comparing with inland wetland. In this study, inland and estuary wetlands were selected to study the potential of CO2 sequestration capacity. It was found that inland wetland had most of soil organic carbon (SOC) derived from plant C, which brought remarkable organic C content and nourished higher microbial biomass, dehydrogenase, and β_glucosidase than estuary wetland. The estuary wetland instead accumulated less SOC, a considerable proportion of which came from tidal waters, therefore supporting lower microbial biomass and enzyme activities than that in inland wetland. However, estuary wetland was evaluated having higher capability in SOC mineralization than inland wetland in consideration of soil respiration (SR) and SR quotient. It was concluded that tidal organic C accelerated the SOC mineralization in estuarine wetland, thus weakening the CO2 sequestration. These results implied the importance of pollution control for reservation CO2 sink function in estuarine wetland. [ABSTRACT FROM AUTHOR]

Microbial cells have been successfully used as biosorbents to remove heavy metals from wastewater. In some cases, dead cells appear to offer more advantages than living cells in the removal and recovery of heavy metal ions from industrial wastewater. Maintaining higher biosorption capability and understanding the biosorption properties of dead cells are the keys to heavy metal removal and recovery from wastewater using dead cells as biosorbents. The present experiment showed that the dead Pseudomonas putida 5-x cells killed by dilute HCl had a higher Ni2+ biosorption capacity due to the retention of a complete cell structure during the acid treatment process. The biosorption process of the dead cells was faster than that of the living cells. Metabolic-independent physical adsorption played a major role in the Ni2+ sorption by the dead cells.The pH obviously affected the biosorption capacity of the dead cells, because of the variation of the hydrogen ion concentration and cell surface property, as well as occurrence of micro-precipitation along with the change of solution pH. Considering both biosorption capacity and desorption efficiency, pH 6.5-7.0 is a suitable condition for Ni2+ biosorption by dead P. putida 5-x cells killed with dilute HCl.

Highlights: What are the main finding? Spirulina platensis was applied to treat mariculture wastewater for N and P removal. Microalgal aggregates were formed under air velocity of 1.75 cm/s or higher. What is the implication of the main finding? Microalgal aggregation was promoted, which was attributed to the protein contents in TB-EPS. P accumulation in biomass was enhanced accompanied by the aggregation process. As an important alternative to alleviate the shortage of wild fishery resources, mariculture is facing increasing challenges on the wastewater treatment, mainly due to the salinity brought from seawater and low nutrient concentration. In this study, Spirulina platensis (S. platensis) was adopted as the target algae stain for synthetic mariculture wastewater treatment, which exhibited excellent adaptability to high-saline wastewater during a 40 days' adaptive culture. Then, the microalgae stain was inoculated into photo-bioreactors with different uplift airflow velocity (UAV) to achieve microalgal aggregation. After 10 days of pre-cultivation and a 30-day granulation process, the maximum nutrient removal rates by S. platensis were 86.5% of TN (to 3.4 mg/L), 98.1% of TP (to 0.1 mg/L) and 95.8% of DOC (to 5.5 mg/L), with 3.5 g/L of biomass content in synthetic wastewater. Analysis of phosphorus and EPS content showed that higher protein content in tightly bound EPS and enhanced P accumulation was accompanied with the microalgal aggregation processes, and P was mainly distributed in the residual rather than the EPS part of microalgal aggregates, indicating that the development of aggregates from suspension S. platensis would benefit not only biomass separation, but also phosphorus recovery, being a potential treatment for simultaneously removing nutrients and recovering mariculture wastewater. [ABSTRACT FROM AUTHOR]

A novel class of organic units (N‐1 and N‐2) and their derivatives (PNNA‐1 and PNNA‐2) with excellent property of ultralong organic room temperature phosphorescence (UORTP) is reported. In this work, N‐1, N‐2, and their derivatives function as the guests, while organic powders (PNCz, BBP, DBT) and polymethyl methacrylate (PMMA) serve as the host matrixes. Amazingly, the color of phosphorescence can be tuned in different states or by varying the host matrixes. At 77 K, all molecules show green afterglow in the monomer state but yellow afterglow in the aggregated state because strong intermolecular interactions exist in the self‐aggregate and induce a redshift of the afterglow. In particular, PNNA‐1 and PNNA‐2 demonstrate distinctive photoactivated green UORTP in the PMMA film owing to the generation of their cation radicals. Whereas the PNNA‐1@PNCz and PNNA‐2@PNCz doping powders give out yellow UORTP, showing matrix‐controlled color‐tunable UORTP. In PNCz, the cation radicals of PNNA‐1 and PNNA‐2 can stay stably and form strong intermolecular interactions with PNCz, leading to a redshift of ultralong phosphorescence. [ABSTRACT FROM AUTHOR]

Prediction of water quality is a critical aspect of water pollution control and prevention. The trend of water quality can be predicted using historical data collected from water quality monitoring and management of water environment. The present study aims to develop a long short-term memory (LSTM) network and its attention-based (AT-LSTM) model to achieve the prediction of water quality in the Burnett River of Australia. The models developed in this study introduced an attention mechanism after feature extraction of water quality data in the section of Burnett River considering the effect of the sequences on the prediction results at different moments to enhance the influence of key features on the prediction results. This study provides one-step-ahead forecasting and multistep forward forecasting of dissolved oxygen (DO) of the Burnett River utilizing LSTM and AT-LSTM models and the comparison of the results. The research outcomes demonstrated that the inclusion of the attention mechanism improves the prediction performance of the LSTM model. Therefore, the AT-LSTM-based water quality forecasting model, developed in this study, demonstrated its stronger capability than the LSTM model for informing the Water Quality Improvement Plan of Queensland, Australia, to accurately predict water quality in the Burnett River. [ABSTRACT FROM AUTHOR]

Aim: To explore whether sequential embryo transfer benefits patients with repeated implantation failure (RIF) undergoing frozen–thawed embryo transfer (FET) cycles. Methods: We included 311 patients with a history of RIF in this retrospective study. We did sequential transfers with a cleavage embryo on day 3 and a blastocyst on day 5 in 77 patients; blastocyst transfers with two blastocysts on day 5 in 80 patients; and cleavage embryo transfers with two cleavage embryos on day 3 in 154 patients. We compared clinical outcomes between the three groups. Results: The clinical pregnancy rate was comparable between the blastocyst transfer group (48.8%), the sequential transfer group(48.1%) and the cleavage embryo transfer group (48.1%). There was no statistically significant difference found (p > 0.05). The ongoing pregnancy and multipregnancy rates were also comparable between the three groups (p > 0.05). The early miscarriage rate was significantly higher in the sequential transfer group (32.4%) compared with the blastocyst group (12.8%) and the cleavage embryo group (12.2%) (p < 0.05). However, after adjusting for confounders, there was no significant difference in early miscarriage rates in the sequential transfer group compared with the blastocyst group (odds ratio [OR], 2.97; 95% confidence interval [CI], 0.85–9.24; p = 0.07) and the cleavage embryo group (OR, 3.03; 95% CI, 0.94–8.06; p = 0.08). Conclusions: Sequential embryo transfer failed to improve clinical outcomes for patients with RIF. [ABSTRACT FROM AUTHOR]